Absence Of PVP Research Articles

Preparation of Gadolinium‐Based Metal‐Organic Frameworks and the Modification with Boron‐10 Isotope: A Potential Dual Agent for MRI and Neutron Capture Therapy Applications

AbstractCancer has recently begun to occur very commonly in humans, and the number of new cancer cases and deaths is also increasing year by year. To reduce these numbers, the development of new materials, which have the potential to be used for both diagnostic and therapeutic purposes, is very significant for sensitively detecting and effectively destroying cancer cells. Therefore, this work purposes the development of gadolinium‐based metal‐organic frameworks (Gd‐MOFs) via solvothermal method under various conditions such as the use of different ligands types, the presence or absence of PVP and variable ligand/metal ratios, and the preparation of silica‐coated and 10B modified Gd‐MOF nanocomposites to fabricate as the potential candidate for simultaneous uses in MRI and the combined neutron capture therapy (GdNCT and BNCT) applications. The XRD patterns of Gd‐MOFs showed the formation of [Gd2(BDC)3(DMF)2(H2O)] structures with 1,4 H2BDC ligand and [Gd(BTC)] structures with 1,3,5 H3BTC ligand. In the presence of PVP by using the least amount of ligands, experimental ligand/Gd ratios were calculated as 1.52 and 1.06 for [Gd2(BDC)3(DMF)2(H2O)] and [Gd(BTC)], respectively, which are very close to theoretical ratio. After the silica coating and 10B modification, the surface appearance of the prepared nanocomposite changed in general, and Gd/10B ratio into nanocomposite was calculated as 3.0, indicating that it could be a useful candidate for the simultaneous GdBNCT and MRI applications.

Polyvinylpyrrolidone Loaded-MnZnFe2O4 Magnetic Nanocomposites Induce Apoptosis in Cancer Cells Through Mitochondrial Damage and P53 Pathway

MnZnFe2O4 ferrite was successfully synthesized using metallic chlorides and polyvinylpyrolidone, by Co-precipitate method. Deferent concentrations of PVP (0.1, 0.3, 0.5, 0.7, and 0.9) wt%, were used as capping agent to stabilize the particles and prevent them from agglomeration. The PVP content had a vital influence on enhancing the properties of the ferrite nanoparticles. From X-ray data the degree of crystallinity and the Lattice constants (a) of the nanoparticles increased from (8.92 nm) and (8.344 A) to (19.94 nm) and (8.395 A) respectively with increasing PVP concentrations. The morphology and average particle size of the MnZn ferrite nanoparticles were evaluated by scanning electron microscopy (SEM), the values were in a good agreement with the XRD results. Fourier transform infrared spectroscopy (FT-IR) confirmed the cubic structure with octahedral and tetrahedral, also indicated the formation of bond between PVP and surface of metallic hydroxide of ferrite nanoparticles. Vibrating sample magnetometer (VSM) analysis was performed for all samples at room temperature, results showed that the specimens exhibited a paramagnetic behavior in the absence of PVP while in the presence of PVP they have super paramagnetic characteristics. The values of saturation magnetization (Ms) (1.78–17.67 emu/g), remnant magnetization (Mr) (0.0022–0.0696 emu/g) also increased with increasing pvp concentration. Polyvinylpyrrolidone loaded-MnZnFe2O4 magnetic nanocomposites were used it alone or as a combination therapy with NIR laser, and alternating magnetic field (AMF) as anti-proliferative agent against breast cancer cell lines AMJ-13, MCF-7,and ovarian cancer cell line SKOV-3 as well as against normal cell line HBL. While, its capability to induce apoptosis was detected using different techniques which is acridine orange/ethidium bromide (AO/EtBr) staining and mitochondrial membrane potential (MMP), and flow cytometry assay membrane potential (MMP). q-PCR was used to investigate the changes in the expression of P53 gene. The influence of Polyvinylpyrrolidone loaded-MnZnFe2O4 magnetic nanocomposites in viability of breast and ovarian cancer cells alone or when they used as a combination therapy with laser photo-thermal therapy and alternating magnetic field (AMF) was also tested using MTT assay. Our results in the present study demonstrated that the inhibition activity of Polyvinylpyrrolidone loaded-MnZnFe2O4 magnetic nanocomposites against treated cancer cell lines increased when Polyvinylpyrrolidone loaded-MnZnFe2O4 nanocomposites used with NIR laser, while highly increased cytotoxic activities were observed after exposure of Polyvinylpyrrolidone loaded-MnZnFe2O4 nanocomposites to induction heating with AMF. Treated cancer cells with polyvinylpyrrolidone loaded-MnZnFe2O4 magnetic nanocomposites significantly increased ROS synthesis, with subsequent reduction of the MMP. The results of the current study show that tested compounds suppressed cancers cells’ proliferation and has a growth inhibitory effect on different cancer cells, resulting in apoptosis as a novel pathway that involves mitochondrial damage mechanism via activated P53. Taken together the present data suggest that the Polyvinylpyrrolidone loaded-MnZnFe2O4 magnetic nanocomposites could be promising therapy protocol for cancer cells.

Two-step electrosynthesis and catalytic activity of CoO−CoO • xH2O-supported Ag, Au, and Pd nanoparticles

Two-step electrosynthesis of CoO-CoO•xH2O-supported metal nanoparticles (MNPs, M = Au, Ag, Pd) was carried out in N,N-dimethylformamide in the absence and in presence of poly(N-vinylpyrrolidone) (PVP) using atmospheric oxygen as both a reagent and a mediator at potentials of its reduction to a superoxide radical anion. In the first step, oxygen reduction in the presence of Co2+ ions added to the solution as a salt or generated by dissolving the Co-anode during electrolysis produces a mixture of cobalt oxide CoO and its hydrated form CoO-CoO • xH2O (CoOxHy ). When Ag+, Au+, Pd2+ ions are added to the obtained solution of CoOx H y, a redox reaction between CoO and the metal ion gives the MNPs and CoO+. In the second step, oxygen-mediated electroreduction of CoO+ serving as the second mediator is carried out, and the redox reaction is completely shifted towards the formation of MNPs. In the absence of PVP, AgNPs (18±4 nm) bind and stabilize completely in the CoOxHy matrix, PdNPs (6±1 nm) stabilize only partially, and AuNPs (21±10 nm) do not bind and, therefore, only their agglomerates are obtained (~200 nm). In the presence of PVP, individual AgNPs (5±2 nm), AuNPs (13±5 nm), PdNPs (3±1 nm) are stabilized in the PVP shell and are bound by the matrix. The obtained nanocomposites M/CoOx H y and M@PVP/CoOxHy catalyze the reduction of p-nitrophenol with sodium borohydride in an aqueous medium. Their catalytic activity is due to MNPs; CoOx H y acts as an inert matrix.

Insights into the Role of Poly(vinylpyrrolidone) in the Synthesis of Palladium Nanoparticles and Their Electrocatalytic Properties.

Four types of palladium (Pd) nanoparticles were prepared from the systems containing PdCl2 or Na2PdCl4 with or without the assistance of poly(vinylpyrrolidone) (PVP). Two types of Pd nanoparticles obtained in the absence of PVP were obviously larger than those synthesized with the assistance of PVP. The former large Pd particles showed typical features in cyclic voltammetry in H2SO4 solution, whereas two types of small Pd nanoparticles did not. However, small nanoparticles treated first in an electrochemical way in 0.5 M KOH solution displayed the adsorption and desorption peaks similar to those of typical Pd-modified electrodes in H2SO4 solution. Large Pd nanoparticles from the PdCl2 synthesis system showed a catalytic specific current of 629 mA/mg in the electrocatalysis of ethanol, whereas large particles from the Na2PdCl4 system showed a current of 262 mA/mg. The maximum catalytic currents of small Pd nanoparticles without surface cleaning treatment were 1382 and 1019 mA/mg for samples from the Na2PdCl4 and PdCl2 systems, respectively, higher than those being treated in KOH solution first, and the electrocatalytic stability of the two untreated samples was better. However, small nanoparticles after the electrochemical treatment can reach the maximum catalytic current faster. The synthesis and structure-property relation of four types of Pd nanoparticles have been discussed and analyzed on the basis of systematically experimental data.

Morphological control of hydrothermally synthesized cobalt oxide particles using poly(vinyl pyrrolidone)

The hydrothermal synthesis of Co3O4 particles using cobalt nitrate as the precursor and citric acid as a weak chelating agent was modulated using poly(vinyl pyrrolidone) (PVP) to control the shape and size of the resulting particles. The molar ratio of PVP to the cobalt in the precursor solution was key to controlling the particle morphology. In the absence of PVP, large truncated cube-like particles with a bimodal size distribution (200 and 1450 nm) are formed. When the molar ratio of PVP/Co is less than ≈ 0.5, the particle size is generally invariant. As the molar ratio of PVP/Co is increased from 0.5 to nearly 2, the cubes with rounded edges are formed, but the hydrodynamic diameter decreases from nearly 1.4 μm to 800 nm at a molar ratio of 1.8. At PVP/Co > 2, there is a significant decrease in the particle size down to 142 nm at PVP/Co = 3.5 and the shape becomes spherical, but the particles remain crystalline, characteristic of Co3O4. The size of Co3O4 particles was also determined using scanning electron microscopy. This size is consistent with the particle size obtained from dynamic light scattering. A competitive growth mechanism between free cobalt ions and PVP-bound cobalt ions in the solution was proposed to explain the influence of PVP on the size and shape of the Co3O4 particles. Due to heavy metal specificity for the binding with PVP and the crystal space group for metal oxides, the evolution in particle shape is not universal with no apparent change in the shape obtained over a similar PVP concentration range for iron oxide.

Fullerene Mediated Electrosynthesis of Silver Nanoparticles in Toluene-DMF

Using C60 and C70 fullerenes as mediators, efficient mediated electrosynthesis of silver nanoparticles (AgNP) in toluene-DMF/ 0.1 M Bu4NBF4 medium was carried out by reduction of Ag+ at the potentials of the fullerene radical anions generation. Synthesis was performed in the absence and in the presence of poly(N-vinylpyrrolidone) (PVP) in the cathodic compartment of a diaphragm-separated cell by addition of Ag+ as AgNO3 into solution and in a single compartment cell by in situ generation of Ag+ by dissolution of an Ag-anode during electrolysis. In all cases, Ag+ ions are quantitatively reduced upon consumption of the theoretical amount of electricity; the generated metal is quantitatively obtained in solution bulk in the form of spherical NP with sizes in the range from 11 ± 2 to 24 ± 9 nm. In electrolysis in a single compartment cell, dispersion of the Ag-anode occurs along with its dissolution and the total current efficiency of AgNP is 131 ÷ 163%. In the presence of PVP, individual AgNP are stabilized in the PVP shell. The isolated Ag/PVP nanocomposite is deposited on a solid support both in individual form and as three-component Ag/PVP/fullerene nanocomposite. In the absence of PVP, the Ag/fullerene nanocomposite is obtained.

Antisolvent precipitation technique: A very promising approach to crystallize curcumin in presence of polyvinyl pyrrolidon for solubility and dissolution enhancement

Curcumin with a vast number of pharmacological activities is a poorly water soluble drug which its oral bioavailability is profoundly limited by its dissolution or solubility in GI tract. Curcumin could be a good anticancer drug if its solubility could be increased. Therefore, the aim of the present study was to increase the dissolution rate of curcumin by employing antisolvent crystallization technique and to investigate the effect of polyvinyl pyrrolidone K30 (PVP) as colloidal particles in crystallization medium on resultant particles. Curcumin was crystalized in the presence of different amounts of PVP by antisolvent crystallization method and their physical mixtures were prepared for comparison purposes. The samples were characterized by scanning electron microscopy (SEM), differential scanning calorimetry (DSC), X-ray powder diffraction (XRPD) and Fourier transform infrared spectroscopy (FT-IR). The solubility and dissolution of the treated and untreated curcumin were also determined. Antisolvent crystallization of curcumin led to the formation of particles with no definite geometric shape. It was interesting to note that the DSC and XRPD studies indicated the formation of a new polymorph and less crystallinity for particles crystallized in the absence of PVP. However, the crystallized curcumin in the presence of PVP was completely amorphous. All crystalized curcumin samples showed much higher dissolution rate compared to untreated curcumin. The amount of curcumin dissolved within 10 for treated curcumin in the presence of PVP (1:1 curcumin:PVP) was 7 times higher than untreated curcumin and this enhancement in the dissolution for curcumin samples crystallized in the absence of PVP was around 5 times. Overall‚ the results of this study showed that antisolvent crystallization method in the absence or presence of small amounts of PVP is very efficient in increasing the dissolution rate of curcumin to achieve better efficiency for curcumin.

Effect of Temperature on the Growth of Silver Nanoparticles Using Plasmon-Mediated Method under the Irradiation of Green LEDs.

Plasmon-mediated shape conversion of spherical silver nanoparticles (NPs) to nanostructures with other shapes under the irradiation of green LEDs (520 ± 20 nm, 35 mw/cm2) at various temperatures (60, 40, 20, 10, 5, and 0 °C) was performed in this study. It was found that the bath temperature used in the reaction can influence the reaction rates, i.e., the times needed for the shape transformation process were 5, 11.5, 25, 45, 72, and 100 h at 60, 40, 20, 10, 5, and 0 °C, respectively. In addition, the bath temperature can also alter the morphologies of the final products. The major products are silver nanoplates at 60, 40 and 20 °C. However, they became decahedral silver NPs at 5 and 0 °C. The percentages of decahedral silver NPs synthesized at 60, 40, 20, 10, 5, and 0 °C are 0%, 1%, 5%, 45%, 73%, and 89%, respectively. Measuring the surface-enhanced Raman spectroscopy (SERS) spectra of the probe molecule R6G in the presence of KBr showed that both silver nanoplate colloids synthesized at 60 °C and decahedral silver NP colloids synthesized at 0 °C in the absence of PVP had good SERS activities.

A Novel Research on Behavior of Zinc Ferrite Nanoparticles in Different Concentration of Poly(vinyl pyrrolidone) (PVP)

Zinc ferrite nanocrystals were prepared from an aqueous solution containing metal nitrates and various of concentrations of poly(vinyl pyrrolidone) (PVP), i.e., 0, 15, 40, and 55 g/L, as a capping agent. To stabilize the particles, they were thermally treated at 873 K, as an optimum calcination temperature. The behaviors of the polymeric precursor were analyzed by use of simultaneous thermo-gravimetry (TG) and derivative thermo-gravimetry analyses (DTG). The presence of the crystalline phase in each sample was confirmed by X-ray diffraction (XRD) analysis. The average particle size and the morphology of the nanoparticles were determined by transmission electron microscopy (TEM), and these parameters were found to differ at various concentrations of PVP. Fourier transform infrared spectroscopy (FT-IR) confirmed the presence of metal oxide bands for all the PVP concentrations and confirmed the absence of organic bands for PVP concentrations less than 55 g/L. Measurements of the magnetization value of the zinc ferrite nanoparticles were obtained at room temperature by using a vibrating sample magnetometer (VSM), which showed that, in the absence of PVP, the sample exhibited a paramagnetic behavior while, in the presence of PVP, samples have a super-paramagnetic behavior.

SAXS and XPS Characterization of Ru/Alumina Catalyst Synthesized by Microwave Irradiation Technique

Ru/Al2O3 catalyst have been synthesized by using two different methods. The aim of the present work is to studythe surface fractal behavior and the formation of Ruthenium metal in the presence and absence of PVP by SAXS and XPS measurement, respectively. Both of Ru-based nanocatalyst supported on Alumina powder has been synthesized in ethylene glycol under microwave irradiation. The samples were also characterized by TEM and FESEM. Nanoparticles with an average diameter about 2 nm and narrow distribution of sizes were obtained. According to XPS results, formation of metal Ru (0) was observed in all samples. The oxides form of Ru in the samples was obviously due to interaction with the air. Furthermore, chlorine content in the systems was still detected.

Synthesis and optical property of ZnO nano-/micro-rods

A series of zinc oxide (ZnO) nano-/micro-rods had been synthesized via solution-based routes. In the hydrothermal route, the obtained ZnO nano-/micro-rods had two topographics. In refluxing procedures, spindly ZnO nanorods were obtained in the presence of poly(vinyl-pyrrolidone) (PVP) and ellipsoid-like nanorods were obtained in the absence of PVP. The products were characterized using X-ray powder diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), and electron diffraction (ED) analysis. Room temperature photoluminescence (PL) spectra of the ZnO products demonstrated a weak UV emission and a broad visible emission for each of the sample. The growth mechanism of 1-D ZnO crystals was discussed briefly.

Effect of hydrophilic polymer on complexing efficiency of cyclodextrins towards efavirenz-characterization and thermodynamic parameters

The present work describes the effect of PVP on the complexation efficiency of cyclodextrins towards efavirenz, a poorly soluble antiretroviral agent imparting irritating sensation to buccal cavity. The phase solubility study indicates 1:1 stoichiometry for binary and ternary systems. DSC and XRPD revealed complete inclusion only in the lyophilized systems. The ternary systems were autoclaved before being lyophilized for the best results. Proton NMR suggests that the chlorobenzene part of benzoxazinone ring of the drug is involved in inclusion and was confirmed by 2D-COESY. The thermodynamic parameters, indicative of complexation efficiency were calculated calorimetrically by determining the interaction enthalpy of efavirenz with cyclodextrins in the presence and absence of PVP. The value of stability constants increased in the order β-CD < HP-β-CD < M-β-CD and is still higher in the presence of PVP illustrating the facilitation of the inclusion. Molar enthalpy of interaction of autoclaved solid formulation determined calorimetrically indicated stronger interaction for efavirenz:M-βCD-PVP system (−12.20 kJ/mol) which showed highest solubility and dissolution rate. The in vitro measurement of permeability showed a ten fold increase in the flux for the autoclaved formulation containing efavirenz-M-β-CD-PVP. In conclusion, encapsulation by cyclodextrins increases the solubility and suppresses the oral irritation of efavirenz. PVP further increases the complexation efficiency and decreases the bulk of cyclodextrins.

Simple preparation and characterization of nickel ferrite nanocrystals by a thermal treatment method

Nickel ferrite nanocrystals were prepared from an aqueous solution containing metal nitrates and poly (vinyl pyrrolidone) (PVP) as a capping agent. To stabilize the particles, they were thermally treated at various temperatures from 623 to 823 K at which calcination occurred, thereby stabilizing the particles, controlling the growth of the nanoparticles, preventing their agglomeration, and creating a uniform distribution of particle sizes. The characterization studies were conducted by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and transmission electron microscopy (TEM). The crystallization was completed between 723 and 823 K, as revealed by the absence of organic absorption bands in the FT-IR spectra Magnetization measurements were obtained at room temperature by using a vibrating sample magnetometer (VSM), which showed that the calcined samples exhibited ferromagnetic behaviors. Finally, we used TEM images and FT-IR spectra to investigate the same process in the absence of PVP and with various of concentrations of PVP for comparison with the results acquired from using the optimum concentration that was used in this work.

Preparation of silver nanoparticles using tryptophan and its formation mechanism

A non-toxic route was used for the preparation of silver nanoparticles using tryptophan (Trp) as reducing/stabilizing agent in the presence of cetyltrimethyl ammonium bromide (CTAB). Role of water soluble neutral polymer poly(vinylpyrrolidone) (PVP) has been studied on the growth of yellow colour silver nanoparticle formation. The synthesized nanostructures were characterized by UV–Visible absorption spectroscopy, transmission electron microscopy (TEM) by observing the size and distribution of silver nanoparticles. As the reaction proceeded, particles grew up to about 10 and 20 nm in the presence and absence of PVP, respectively, as determined by TEM. The formed nanoparticles showed the highest absorption plasmon band at 425 nm. Rate of silver sol formation increases with the [Trp], [CTAB] and [PVP], reaching a limiting value and then decreases with the increase in concentrations of these reagents. It was observed that nanoparticles are spherical, aggregated and poly dispersed in the absence and presence of PVP, respectively. On the basis of kinetic data, a suitable mechanism is proposed and discussed for the silver sol formation.

Finding a Facile Method to Synthesize Decahedral Silver Nanoparticles through a Systematic Study of Temperature Effect on Photomediated Silver Nanostructure Growth

AbstractTo the best of our knowledge, few reports have been concerned with the effect of temperature on photomediated silver nanostructure growth. In this work, the shape evolution from spherical silver nanoparticles to silver nanoprisms and nanostructures in other shapes under the irradiation of a sodium lamp (λmax = 589 nm, 0.66 W/cm2) at various temperatures (i.e., 15, 40, 60, and 80 °C) were studied by recording the TEM images and time‐course UV‐vis‐NIR spectra of the silver colloids. From TEM and spectra analysis, it was found that the photomediated silver nanoparticle shape conversion process would be faster at a higher temperature, i.e., ca. 2 hours at 80 °C, and slower at a lower temperature, i.e., ca. 17 hours at 15 °C. The silver nanoplates synthesized at a higher temperature had a narrower size distribution and were thicker than those synthesized at a lower temperature. Some decahedral silver nanoparticles, about 10% of the final irradiation products, were observed in the synthesis (with a sodium lamp) at 15 °C. In order to produce a higher yield of decahedral silver nanoparticles, the sodium lamp was replaced with blue LEDs (λmax = 450 nm), which have a wavelength closer to the SPR of decahedral silver NPs (ca. 490 nm). The decahedral silver nanoparticles with a fairly narrow size distribution were obtained by irradiating the spherical nanoparticle colloids with the blue LEDs at 2 °C in the absence of PVP or other large‐molecular‐mass surfactants.

Utilization of Poly(N-vinyl-2-pyrrolidone) to Enhance the Performance Properties as well as UV Protection of Ester Crosslinked Cotton Fabrics

Poly( N-vinyl-2-pyrrolidone) (PVP) was used as an additive in polycarboxylic acids finishing bathes. It was found that treating cotton fabric with aqueous solution containing 4% PVP, 8% citric acid, and 8% sodium hypophosphite monohydrate, followed by drying at 100°C for 3 minutes and then curing at 180°C for 90 seconds enhance the wrinkle recovery angle and tensile strength of the finished fabrics, as compared with fabrics treated under the same conditions but in the absence of PVP. The finished fabrics were post-treated separately with aqueous solutions of copper acetate and zinc acetate with the aim of improving the UV protection of these fabrics. According to the obtained data, copper acetate was found to have higher extent of UV protection than zinc acetate.

Polymer Adsorption Effects on Colloidal Stabilities of Ceria Particles and Chemical Mechanical Polishing of Silicone Oxide Films by Ceria Particles

Characterization of ceria particles in the presence of poly(vinyl pyrrolidone) (PVP) was performed by the measurements of adsorbed amounts of PVP, average sizes, ζ potentials, and back scattering intensities of the ceria particles as functions of PVP molecular weight and PVP concentration. In particular, the measurements of the hydrodynamic average diameters, ζ potentials, and back scattering intensities of the ceria particles have been carried out for the re-dispersed ceria particles, whose particles were washed by the dispersion medium to remove the free PVP chains and then they were dispersed again in the corresponding dispersion medium after adsorption of PVP on the ceria particles and sedimentation of the ceria particles. PVP adsorption on the ceria surfaces enhanced the stability of ceria particles by the steric stabilization of the thicker adsorbed layer of PVP for the larger molecular weight of PVP. Moreover, the chemical mechanical polishing (CMP) of SiO2 films deposited on Si wafers has been performed by the ceria slurries without and with PVP. Removal rates of the deposited SiO2 films were increased with an increase in the adsorbed amount of PVP and their magnitudes were larger than that in the absence of PVP.

Poly(4-vinylpyridine) catalyzed selective methanolysis of methyl and methylene bromides

The effect of poly(4-vinylpyridine) (PVP) on the methanolysis of methyl bromide and methylene bromide was studied at temperatures between 75 °C and 125 °C. PVP acts as an efficient HBr scavenger promoting the formation of dimethyl ether (DME) and dimethoxymethane (DMM) from the corresponding bromomethanes and methanol in moderate yields with high selectivity. No reaction was observed in the absence of PVP under the conditions adopted. The activity of the catalyst remained unchanged even after five cycles showing the efficacy and application of the polymer as an environmentally green reagent as well as catalyst in this methanolysis reaction.

Effects of Different Concentrations of Poly(vinyl pyrrolidone) on the Solubility of Lamotrigine and Diazepam in Ethanol + Water Mixtures at 298.2 K

The effects of poly(vinyl pyrrolidone) K30 (PVP) (1) on the solubility of lamotrigine (2) and diazepam (2) at 298.2 K are reported for ethanol (3) + water (4) mixtures at five different concentrations (0.0001, 0.0005, 0.001, 0.005 and 0.01) g·mL−1 of PVP. The general version of the Jouyban−Acree model was fitted to the solubility data of each drug in a given concentration of PVP. The largest mean relative deviation (MRD) was 14 %, that is, for diazepam in the presence of (0.0005 and 0.001) g·mL−1 of PVP, and the lowest MRD was 4 % for lamotrigine in the presence of 0.01 g·mL−1 of PVP. The overall MRD for lamotrigine and diazepam was 9 %. A modified version of the Jouyban−Acree model was used to model the simultaneous effects of the ethanol and PVP on the solubility employing experimental solubility of drugs in water and ethanol in the absence of PVP. The MRDs for diazepam and lamotrigine were 23 % and 10 %, respectively, with the overall value of 17 %.

Hydrothermal synthesis and self-assembly of magnetite (Fe 3O 4) nanoparticles with the magnetic and electrochemical properties

We have developed a simple hydrothermal route to prepare the necklace-shaped superstructures self-assembled by magnetite (Fe 3O 4) nanoparticles coated with poly (vinyl pyrrolidone) (PVP). The as-prepared samples were characterized by means of X-ray powder diffraction (XRPD), Fourier transform infrared (FTIR) spectra, transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), thermal gravimetric analysis (TGA), magnetic hysteresis loop, and cyclic voltammetry. Magnetic measurement results reveal that the necklace-shaped superstructures show smaller magnetization compared with those of randomly distributed magnetite nanoparticles obtained in the absence of PVP. The electrochemical characterization was carried out by cyclic voltammetry, which indicates that the Fe 3O 4 sample in 1 mol L −1 Na 2SO 3 aqueous electrolyte is of an excellent electrode material for supercapacitor at the scan rate of 2 mV S −1 in the range of −1.0 to 0.2 V.