Dissolution Properties of 2-(Dinitromethylene)-5-methyl-1,3-diazacyclopentane in Dimethyl Sulfoxide and N-Methyl Pyrrolidone

The molar enthalpies of dissolution for 2-（dinitromethylene）-5-methyl-1,3-diazacyclopentane（DNMDZ） in dimethyl sulfoxide（DMSO） and N-methyl pyrrolidone（NMP） were measured using an RD496-2000 Calvet microcalorimeter at 298.15 K under atmospheric pressure.Empirical formulae for the calculation of the molar enthalpies of dissolution（Δ diss H） were obtained from the experimental data of the dissolution processes of DNMDZ in DMSO or NMP.The relationships between the rate constant（k） and the molality（b） and between the reaction order（n） and the molality（b） were determined.The corresponding kinetic equations describing the two dissolution processes were dα/dt=10^-2.16（1-α） ^1.01 for the dissolution of DNMDZ in DMSO,and dα/dt=10^-2.02（1-α）^ 0.85 for the dissolution of DNMDZ in NMP,respectively.

Rational Synthesis of Cylindrical Silver Single-crystalline Nanowires via Poly(vinyl pyrrolidone) Reduction of AgCl

We presented a simple yet convenient hydrothermal approach for the large-scale synthesis of uniform cylindrical silver (Ag) single-crystalline nanowires with diameters of about 25 nm and lengths of 1-4 μm. Poly(vinyl pyrrolidone) (PVP) was used as a reducing agent, and AgCl was used as a precursor to deliberately control [Ag^+] at a low degree in the overall reaction process through its dynamic equilibrium by directly reducing AgCl with PVP at a quasi-equilibrium growth condition. The as-obtained products were characterized by powder X-ray diffraction (XRD) patterns, field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), infrared spectra (IR) and Raman spectra. Factors such as [PVP], reaction temperature, time, and species of reducing agents and precursors were investigated to have strong influences on the morphologies and structures of the resultant Ag nanostructures. The wire diameter can conveniently be adjusted between 25 and 50 nm by simply adjusting [PVP], reaction temperature and reducing agent species. The as-synthesized silver nanowires can be self-assembled into perfect order arrays after being dried on tin foil due to the PVP coating on the surface, the circular cross-section and the uniform diameter of the Ag nanowires. These special silver nanowires with a core-shell structure as well as their spontaneous self-assembly of order arrays are expected to provide potential applications in flexible conductors, dielectric materials, electromagnetic shielding materials and nano-devices.

The ion balance of Shotokuseki extract promotes filaggrin fragmentation and increases amino acid production and pyrrolidone carboxylic acid content in three-dimensional cultured human epidermis

Natural moisturizing factor(NMF)in the stratum corneum contributes to the retention of moisture there.The purpose of this study was to determine the penetration of ions in Shotokuseki extract(SE)into the three-dimensional cultured epidermis and the effect of NMF on the biosynthesis of amino acids and pyrrolidone carboxylic acid formation.Vari-ous ions,amino acids and pyrrolidone carboxylic acid were quantified by inductively coupled plasma mass spectrom-etry,fully automatic amino acid analyzer or high-performance liquid chromatography(HPLC)in three-dimensional cultured epidermis after application of SE.Gene expression levels of profilaggrin,calpain1,caspase14,and bleomycin hydrolase,which are involved in NMF production,were determined by reverse-transcription qPCR and bleomycin hydrolase activity was determined by aminopeptidase assay.The application of SE increased Na,K,Mg,Ca,Al,and Fe levels in three-dimensional cultured epidermis.The mRNA levels of the starting material of amino acid synthesis profilaggrin,and calpain1 and bleomycin hydrolase,which are involved in its fragmentation,increased.The activity of bleomycin hydrolase also increased.Furthermore,the levels of amino acids and pyrrolidone carboxylic acid increased in the three-dimensional cultured epidermis.This suggests that the ionic composition of SE may be involved in its moisturizing effect on the stratum corneum.

Thermo-Responsive Electrospun Nanofibers from Poly( N-isopropylacrylamide )/Polyvinyl Pyrrolidone Blends

A novel nanofiber composite poly(N-isopropylacrylamide)(PNIPAAm)/polyvinyl pyrrolidone(PVP)was successfully prepared by electrospinning.Analogous medicated fibers loaded with ketoprofen(KET)as a model drug were prepared.X-ray diffraction(XRD)demonstrated that the drug was presented in the fibers with an amorphous form.Both scanning and transmission electron microscopy showed that the fibers had an even diameter and smooth surface,and no phase separation was observed.The KET loaded nanofibers did not affect the morphology of the fibers,and no drug aggregation was separated from the polymer fibers.Water contact angle measurements proved that the PNIPAAm/PVP fibers switched from hydrophilic to hydrophobic when the temperature increased the lower critical solution temperature of 32℃.In vitro drug release studies were also undertaken and the result indicated that the PNIPAAm/PVP blend nanofiber presented the properties of the two polymers,having temperature-sensitive systems with sustained release properties.In addition,MTT assay demonstrated that the nanofiber film was non-toxic and suitable for cell growth.Thus,the nanofiber can be used as thermoresponsive carriers for sustained release of poor water soluble drugs.

Separation Performance of Sodium Alginate/Poly(Vinyl Pyrrolidone)Membranes for Aqueous/Dimethylformamide Mixtures by Vapor Permeation and Vapor Permeation with Temperature Difference Methods

In this study sodium alginate (NaAlg)/poly (vinyl pyrrolidone) (PVP) blend membranes were prepared and crosslinked with CaCl2 (0.1 Molarity (M)) for the separation of aqueous/dimethylformamide (DMF) mixtures. Membranes were characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and their performance was examined by varying experimental parameters such as feed composition (0 - 100 wt%), operating temperature (30℃ - 50℃) and membrane thickness (30 - 90 micrometer (μm)). Blending NaAlg with PVP, decreased separation factor whereas increased the permeation rate as the permeation temperature was increased in Vapor Permeation (VP) and Vapor Permeation with Temperature Difference (TDVP) methods. In the TDVP method, the separation factors increased and the permeation rates decreased as the temperature of the membrane surrounding is decreased. The highest separation factor of 60 was obtained in TDVP method for 90 wt% DMF concentration in the feed.

The Crystallization Behavior Regulating Nature of Hydrogen Bonds Interaction on Polyamide 6,6 by Poly(vinyl pyrrolidone)

The crystallization behavior of polyamide 6,6(PA66) under complex flow field is of great importance for its final mechanical properties.Poly(vinyl pyrrolidone)(PVP) was applied as crystallization modifying agency to improve processability of PA66.The regulation nature on hydrogen bonds(H-bonds) interaction of PVP was studied upon cooling process.As revealed by in situ FTIR,the sample with 5 wt% PVP displays decreased enthalpy change(ΔH) for both the generation of H-bonds and the transition of H-bonds from “disordered” to “ordered” state,which illustrates the molecular mechanism for the regulation of crystallzation behavior.Moveover,2D-WAXD is applied to reveal the evolution of microstructure for sample under external injection field.Hermans orientation factor(f_(H)) decreases obviously with the addition of PVP,because the relaxation of chain segments is promoted as well the crystallization is retarded.The above crystallization and microstructure changes during the processing provokes the improvement of processability without the apparent sacrifice of mechanical properties.

The Influence of Tartaric Acid in the Silver Nanoparticle Synthesis Using Response Surface Methodology

Silver nanoparticles(AgNPs)synthesized using tartaric acid as a capping agent have a great impact on the reaction kinetics and contribute significantly to the stability of AgNPs.The protective layer formed by tartaric acid is an important factor that protects the silver surface and reduces potential cytotoxicity problems.These attributes are critical for assessing the compatibility of AgNPs with biological systems and making them suitable for drug delivery applications.The aim of this research is to conduct a comprehensive study of the effect of tartaric acid concentration,sonication time and temperature on the formation of silver nanoparticles.Using Response Surface Methodology(RSM)with Face-Centered Central Composite Design(FCCD),the optimization process identifies the most favorable synthesis conditions.UV-Vis spectrum regression analysis shows that AgNPs stabilized with tartaric acid are more stable than AgNPs without tartaric acid.This highlights the increased stability that tartaric acid provides in AgNP ssssynthesis.Particle size distribution analysis showed a multimodal distribution for AgNPs with tartaric acid and showed the smallest size peak with an average size of 20.53 nm.The second peak with increasing intensity shows a dominant average size of 108.8 nm accompanied by one standard deviation of 4.225 nm and a zeta potential of−11.08 mV.In contrast,AgNPs synthesized with polyvinylpyrrolidone(PVP)showed a unimodal particle distribution with an average particle size of 81.62 nm and a zeta potential of−2.96 mV.The more negative zeta potential of AgNP-tartaric acid indicates its increased stability.Evaluation of antibacterial activity showed that AgNPs stabilized with tartaric acid showed better performance against E.coli and B.subtilis bacteria compared with AgNPs-PVP.In summary,this study highlights the potential of tartaric acid in AgNP synthesis and suggests an avenue for the development of stable AgNPs with versatile applications.

EFFECT OF SOLUTION EXTRUSION RATE ON MORPHOLOGY AND PERFORMANCE OF POLYVINYLIDENE FLUORIDE HOLLOW FIBER MEMBRANES USING POLYVINYL PYRROLIDONE AS AN ADDITIVE

Polyvinylidene fluoride （PVDF） hollow fiber membranes prepared from spinning solutions with different polyvinyl pyrrolidone （PVP） contents （1% and 5%） at different extrusion rates were obtained by wet/dry phase process keeping all other spinning parameters constant. In spinning these PVDF hollow fibers, dimethylacetamide （DMAc） and PVP were used as a solvent and an additive, respectively. Water was used as the inner coagulant. Dimethylformamide （DMF） and water （30/70） were used as the external coagulant. The performances of membranes were characterized in terms of water flux, solute rejection for the wet membranes. The structure and morphology of PVDF hollow fiber were examined by BET adsorption, dry/wet weight method and scanning electron microscopy （SEM）. It is found that the increase in PVP content and extrusion rate of spinning solution can result in the increase of water flux and decrease of solute rejection. The improvements of interconnected porous structure and pore size are induced by shear-thinning behavior of spinning solution at high extrusion rates, which could result in the increase of water flux of hollow fiber membranes. The increase of extrusion rate also leads to the increase of membrane thickness due to the recovery effect of elastic property of polymer chains.

Bifunctional flame retardant solid-state electrolyte toward safe Li metal batteries

Solid polymer electrolytes(SPEs)are one of the most promising alternatives to flammable liquid electrolytes for building safe Li metal batteries.Nevertheless,the poor ionic conductivity at room temperature(RT)and low resistance to Li dendrites seriously hinder the commercialization of SPEs.Herein,we design a bifunctional flame retardant SPE by combining hydroxyapatite(HAP)nanomaterials with Nmethyl pyrrolidone(NMP)in the PVDF-HFP matrix.The addition of HAP generates a hydrogen bond network with the PVDF-HFP matrix and cooperates with NMP to facilitate the dissociation of Li TFSI in the PVDF-HFP matrix.Consequently,the prepared SPE demonstrates superior ionic conductivity at RT,excellent fireproof properties,and strong resistance to Li dendrites.The assembled Li symmetric cell with prepared SPE exhibits a stable cycling performance of over 1200 h at 0.2 m A cm^(-2),and the solid-state LiFePO_4||Li cell shows excellent capacity retention of 85.3%over 600 cycles at 0.5 C.

Physicochemical properties of β-cyclodextrin solutions and precipitates prepared from injectable vehicles

β-Cyclodextrin( β-CyD) is cyclic oligosaccharide of a glucopyranose, containing a relatively hydrophobic central cavity and hydrophilic outer surface. However, the usefulness of β-CyD is limited owing to its low aqueous solubility whereas we found that its apparent high solubility was evident in some injectable solvents including 2-pyrrolidone(PYR), Nmethyl pyrrolidone(NMP) and dimethyl sulfoxide(DMSO). Therefore, in the present study, the physicochemical properties of the 30–60% w/w β-CyD in PYR, NMP and DMSO were investigated such as viscosity, water resistant, matrix formation rate and syringeability. The higher the concentration of β-CyD resulted in the increased viscosity and the higher force and energy of syringeability. β-CyD in PYR gave the highest viscosity which contributed to the lowest syringeability while β-CyD in DMSO exhibited the highest syringeability. The β-CyD in DMSO and NMP exhibited the higher rate of matrix formation. β-CyD in PYR showed the highest water resistant for phase separation while β-CyD in NMP gave the faster de-mixing rate compared to that from PYR. The difference in physicochemical properties of β-CyD dried ppts studied by scanning electron microscope(SEM), differential scanning calorimetry(DSC), X-ray diffraction(XRD), Fourier-transform infrared spectroscopy(FT-IR) and thermogravimetric analysis(TGA) revealed that there was partial complexation of β-CyD with respective solvents. Both solution and precipitate characteristic properties will be useful for using β-CyD in further investigation as matrix material dissolved in the injectable vehicles as the in situ forming gel for periodontitis treatment.

Hydrothermal synthesis and photoluminescence behavior of CeO_2 nanowires with the aid of surfactant PVP

Well-crystalline CeO_2 nanowires were prepared via a surfactant-assisted hydrothermal process.Reaction temperature and reaction time were changed for the determination of optimal synthesis parameters.The as-obtained products were characterized by X-ray diffraction （XRD）,high-resolution transmission electron microscopy（HRTEM）,and field emission scanning electron microscopy（FESEM）.The results show that single crystal CeO_2 nanowires with high yield and good uniformity can be obtained hydrothermally at 180℃for 12 h with the aid of 2.0 g surfactant（polyvinyl pyrrolidone,PVP）.The role of PVP was then discussed and a possible growth mechanism was proposed. Moreover,room temperature photoluminescence（PL） spectra were obtained for these CeO2 nanowires,which are believed to be related to the abundant defects in these nanostructures.

PVA/PVP blend polymer matrix for hosting carriers in facilitated transport membranes: Synergistic enhancement of CO2 separation performance

CO2 separation performance in facilitated transport membranes has been reported depended not only on the CO2 carrier properties but also to a great extent on the polymeric matrix regarding the capacity of retaining water and carriers as well as the processability for coating defect-free ultra-thin films. In this study, the blends of hydrophilic polymers polyvinyl pyrrolidone(PVP) and polyvinyl alcohol(PVA) were studied to find an optimal polymer matrix to host carriers in facilitated transport membranes for enhanced CO2 separation. It is found out that the optimized blend is 50/50 PVA/PVP by weight, which shows a significant increase in the water uptake(from 63 to 84%) at equilibrium state compared to the neat PVA. Polyethyleneimine(PEI) was employed to provide sample carriers to evaluate the synergistic effect of PVA and PVP on the CO2 separation performance. A thin film composite(TFC) membrane of the optimized blend(50/50 PVA/PVP with 50 wt% PEI) was fabricated on polysulfone(PSf) porous support. The fabrication of the TFC membranes is simple and low cost, and CO2 permeance of the optimized blend membrane is nearly doubled with the CO2/N2 selectivity remained unchanged, showing great potential for industrial applications of the resulted membranes.

Absorption Capability Comparison of Two Kinds of Super Absorbent Resins from Carboxymethyl Cellulose

The two kinds of super absorbent resins from carboxymethyl cellulose were synthesized with the potassium persulphate and methylenebisacrylamide as initiator and cross linker respectively by radical polymerization in aqueous solution. Thestructures of the two resins were characterized with Fourier transform infrared spectroscopy FTIR, scanning electron miscroscopy （SEM）, and environment scanning electron miscroscopy （ESEM）, the results indicate that the fibriform of the carboxymethyl cellulose （CMC） is disappeared and the crusslink networks in eopolymer of carboxymethyl cellulose-graft-polyacrylic acid（CMC-g-PAA） are denser than that of eopolymer of carboxymethyl cellulose-graft-poly （acrylic acid-co-N-vinyl Pyrrolidone） （CMC-g- PAA-co-PVP）. The comparison between the two resins in absorption capacities is that CMC-g-PAA is better in the water-keep capability being heated, while CMC-g-PAA-co-PVP is better in the water absorbency and salt resistance.

Properties of Zinc Ferrite Nanoparticles Due to PVP Mediation and Annealing at 500°C

In contributing to the improvement of Ferrite Magnetic nanoparticles, the effects of Poly (Vinyl Pyrrolidone) (PVP) and annealing on the structural and magnetic properties of Zinc ferrite nanoparticles (ZFNPs) synthesis were investigated in this work. The effects were evaluated using the X-ray diffraction (XRD) spectroscopy, Scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and Vi-brating sample magnetometer (VSM). The XRD analysis confirms a good formation of the inverse spinel crystal structure with an average particle size of 1.3 nm to 15.2 nm and from 1.6 nm to 21.1 nm for the ZFNPs as-prepared and PVP mediated ZFNPs for the un-annealed and annealed samples, respectively. The SEM image reveals an increase in the particle size for both the as-prepared and PVP mediated samples after annealing at 500°C. The FTIR also reveals the inverse spinel structure for the as-prepared and annealed samples, which witnesses a vibrational red shift towards a higher wave number for the annealed samples. The VSM analysis indicates the superparamagnetic behavior of PVP mediated and annealed sample with zero remanence magnetization (Mr) and Coercivity (Hc). The saturation magnetization (Ms) increases from 1.31 emu/g, for the as-prepared samples, to 4.31 emu/g after the annealing and from 1.18 emu/g, for the PVP mediated, to 6.38 emu/g after annealing. These effects have been attributed to the cationic re-arrangement on the lattice site after the annealing. This presents a superior material for various applications in nanotechnology.

Photo-triggered Intramolecular Radical Tandem Regioselective Alkylation/Cyclization of 1,6-Dienes with Redox-Active Esters Enabled by an EDA Complex

A photocatalyst-and metal-free radical tandem alkylation/cyclization between 1,6-dienes and redox-active esters has been devel-oped,affording a series of N-aryl pyrrolidine-2-ones in moderate to good yields.The transformation is driven by the formation of an electron-donor-acceptor(EDA)complex and a subsequent single electron transfer(SET)process.This photocatalyst-free protocol features excellent regioselectivity,mild conditions and broad substrate scope,providing a facile access to 3-alkyl-3,4-dimethyl-1-phe-nylpyrrolidin-2-one.

Effect of Polymer Inclusion in Preparation of Thick LZO Buffer Layers for YBCO Coated Conductors

In this work, water-based precursor solutions suitable for dip-coating of thick La2Zr2O7 （LZO） buffer layers for coated conductors on Ni-5%W substrates with an inclusion of polymeric polyvinyl pyrrolidone were developed. The effect of varying percentage of the polymer addition on the preparation of the deposited films with maximum crack-free thickness was investigated. This novel water-based chemical solution deposition method involving polymers in two different chelate-chemistry compositions revealed the possibility to grow single, crack-free layers with thicknesses ranging from 140 to 280 nm, with good crystallinity and epitaxial growth. The effect of increasing polymer concentrations on the morphology and the structure of the films was studied. The appropriate buffer layer action of the films in preventing Ni diffusion was studied by X-ray photoelectron spectroscopy.

Application of solvent evaporation technique for pure drug crystal spheres preparation

An innovative application ofthe solventevaporation technique was suggested.Solventevaporation tech nique is a technique for drug encapsulation and nanosphere preparation.The widely used technique is also facing the problem of low actual drug entrapment percent,which is not economic from the industrial view.The goal of this work is trying to use the advantage of this technique concerning the product sphericity and the ability to control particle size,to prepare a drug as pure crystals spheres.Ibuprofen is selected as a model drug.The spheres are formed by using Polyvinyl pyrrolidone(PVP)or Polyethylene glycol(PEG)as an anti-aggregating agent but not formed on using tween or span.Particle size and actual drug content depend on the concentrations the anti-aggregating agent used.Surfaces of the drug crystal spheres are porous with empty sphere internal structure on using PvP but spongy and rough on using PEG.The drug has its identity chemical form in the drug crystal spheres.IR scan of spheres prepared on using PEG showed a characteristic ether peak.DSC showed melting endothermic peak of PEG,but X-ray showed minor change in the drug crystal patterns.Drug release profiles from crystal spheres prepared with the same anti-aggregating agent are close to each other.The drug release profiles from drug crystal spheres prepared by using PEG are more controlled than that prepared by using PVP.The drug release mechanism is diffusion.It was concluded that,the same technique could be suggested for preparation ofother biomedical material in pure crystals spheres with controlled particle size.These properties may encourage to prepare very small particles with spherical shape for inhalation or injection as an innovative particle technology application for the widely used technique.

A GQD-based composite film as photon down-converter in CNT/Si solar cells

Graphene quantum dots (GQDs), have unique quantum confinement effects, tunable bandgap and luminescence property, with a wide range of potential applications such as optoelectronic and biomedical areas. However, GQDs usually have a strong tendency toward aggregation especially in making solid films, which will degrade their optoelectronic properties, for example, causing undesired fluorescence quenching. Here, we designed a composite film by embedding GQDs in a polyvinyl pyrrolidone (PVP) matrix through hydrogen bonding with well-preserved fluorescence, with a small addition of acid for compensating the poor conductivity of PVP. As a multifunctional solid coating on carbon nanotube/silicon (CNT/Si) solar cells, the photon down-conversion by GQDs and the PVP anti-reflection layer for visible light lead to enhanced external quantum efficiency (by 12.34% in the ultraviolet (UV) range) and cell efficiency (up to 14.94%). Such advanced optical managing enabled by low-cost, carbon-based quantum dots, as demonstrated in our results, can be applied to more versatile optoelectronic and photovoltaic devices based on perovskites, organic and other materials.

Investigation of the effect of in-situ grown PPy on low frequency dielectric properties and other properties of PVA-PVP blend film

Present study is carried out to understand the effect of conducting polymer,polypyrrole(PPy)on structural,morphological,ther­mal and dielectric properties of bio-compatible polymer blend film of polyvinyl alcohol(PVA)and polyvinyl pyrrolidone(PVP).The growth of PPy in the matrix of PVA-PVP was analyzed using XRD,FT-IR and SEM studies.The shifting in positions and broadening of XRD diffraction peaks of PVA-PVP-PPy from that of PVA-PVP indicates the structural modification and reduction in the crystallinity of the PVA-PVP due to incorporation of PPy.The SEM studies suggest scattered growth of PPy in PVA-PVP matrix at lower concentration of pyrrole monomer.As the monomer concentration is increased,the uniform and interconnected growth of PPy was observed in SEM micrographs.The TGA thermograms show faster thermal degradation of PVA-PVP-PPy films at lower temperature as compared to PVA-PVP films.The blend films of PVA-PVP-PPy exhibited enhanced values of dielectric constant and ac conductivity as compared to the virgin blend film which are observed to increase with increasing con­centration of PPy.The high dielectric constant with high ac conductivity exhibited by PVA-PVP-PPy film suggests its possible application as flexible dielectric material for the development of biosensors,energy storage devices in field of green organic electronics.