Scattering Electron Microscopy Research Articles

Tuning Ion Diffusivity and High-Rate Cycling Performance Via Graphite Exfoliation for Rechargeable Aluminum-Graphite Batteries

Rechargeable aluminum-graphite batteries using chloroaluminate-containing ionic liquid electrolytes store charge when chloroaluminate anions (e.g. AlCl4 -) intercalate into graphite1,2. Such batteries utilize electrodes that are globally abundant, low-cost, and safe, while exhibiting ultra-fast rate capabilities, high cycle life and discharge voltages of ca. 2 V. Recently, we elucidated the relationship between graphite structure and macroscopic electrochemical properties such as high-rate performance and the maximum intercalation composition.3 Variable-rate cyclic voltammetry (CV) revealed potential-dependent transport regimes that yield new insights into their ultra-fast rate capabilities. To directly observe the chloroaluminate species intercalated within the graphite electrodes, we performed solid-state 27Al MAS NMR measurements, which revealed their various local environments and populations. To aid the interpretation of the experimental results, DFT calculations were performed to compute the magnitude of 27Al NMR shift contributions due to varying graphite d-spacing, aromatic ring-current shielding, and quadrupolar interactions.With this increased understanding of the elusive transport mechanism of sterically-bulky chloroaluminates, the current technological objective is to improve the high-rate capacity retention of synthetic graphite electrodes. To tune the ionic diffusivity within the graphite framework, we employed liquid-phase exfoliation and centrifugation to modify the c-axis thickness of the highly-ordered pristine graphites, generating few-layered graphene structures that we characterized using Atomic Force Microscopy (AFM), Dynamic Light Scattering (DLS) and Transmission Electron Microscopy (TEM). In full-cell electrochemical tests of the exfoliated-graphite electrodes, variable-rate galvanostatic cycling revealed increased capacity retention (~75% @ current density of 960 mA/g, compared to ~43% for non-exfoliated synthetic graphite). Furthermore, galvanostatic intermittent titration technique (GITT) experiments revealed modified ionic diffusivity and ohmic resistances. These results are expected to aid the rational design of graphite electrodes for enhanced performance in aluminum-graphite batteries.(1) Lin, M.-C.; Gong, M.; Lu, B.; Wu, Y.; Wang, D.-Y.; Guan, M.; Angell, M.; Chen, C.; Yang, J.; Hwang, B.-J.; Dai, H. An Ultrafast Rechargeable Aluminium-Ion Battery. Nature 2015, 520, 324–328.(2) Sun, H.; Wang, W.; Yu, Z.; Yuan, Y.; Wang, S.; Jiao, S. A New Aluminium-Ion Battery with High Voltage, High Safety and Low Cost. Chem. Commun. 2015, 51, 11892–11895.(3) Xu, J. H.; Turney, D. E.; Jadhav, A. L.; Messinger, R. J. Effects of Graphite Structure and Ion Transport on the Electrochemical Properties of Rechargeable Aluminum-Graphite Batteries. ACS Appl. Energy Mater. 2019, 2, 7799–7810.

Early blight disease management by herbal nanoemulsion in Solanum lycopersicum with bio-protective manner

Early blight, caused by Alternaria solani is one of the most devastating disease affecting to the Solanum lycopersicum (tomato), reducing its productivity by 80%. The present study illustrates the synthesis of nanoemulsion using peppermint oil for potent antimicrobial activity against A. solani. A peppermint oil based nanoemulsion (PNE) was synthesized which was further characterized by Dynamic Light Scattering and Transmission Electron Microscopy. The nano-droplets present in nanoemulsion were spherical in shape with average size <100 nm. In-vitro antimicrobial activity of PNE was examined against A. solani with the carbendazim as positive control. A green-house study was performed to evaluate the antimicrobial efficacy and plant immunity developed by nanoemulsion as well as compared with carbendazim, chemical fungicide. PNE was much competent to reduce the disease severity up to 68.7% at 14th day and 87.5% at 21st day respectively. Physiological modulation was showed in tomato plants against A. solani, they were confirmed by measured the physical parameters, plant physiology, changes in leaf morphology and stress responses. A significant changes were found in proline and lipid peroxidation content in infected plants whereas nanoemulsion treated infected plants was able to cope-up from stress condition. Physical parameters and Scanning Electron Microscopy (SEM) analysis also revealed the similar observations. A reduced photosynthesis rate and transpiration rate were found in diseased plants as compared to other treatments, although stomatal conductance was not much affected. Defence responsive gene expression also up-regulated in PNE treated diseased plants than pathogen alone. Thus, the current study demonstrated the peppermint oil based nanoemulsion was more efficacious than chemical fungicide to early blight disease management in Solanum lycopersicum.

SERS Activity of Silver Nanosphere, Triangular Nanoplates, Hexagonal Nanoplates and Quasi-Spherical Nanoparticles: Effect of Shape and Morphology

In this work, we prepared different morphologies of silver nanoparticles: nanosphere, triangular nanoplates, hexagonal nanoplates, and quasi-spherical shapes, through one-step synthesis. Hydrogen peroxide was used as the oxidizing agent during the reduction of silver nitrate by sodium borohydride, in the presence of tri-sodium citrate and poly-vinyl-pyrrolidone. The obtained silver nanoparticles were fully characterized by UV-Vis spectroscopy, Dynamic Light Scattering and Scanning Electron Microscopy, and successfully used as Surface Enhanced Raman Scattering (SERS) substrates. The effect of shape and morphology on the Raman scattering enhancement was evaluated by using methylene blue as target molecules. The Raman measurements demonstrated that the prepared substrates are reliable and sensitive with analytical enhancement factors, estimated to be around 105 with a concentration of methylene blue 1 μM. When triangular and hexagonal nanoplates were tested with different concentrations of analyte, they demonstrated a good linearity in Raman intensity with a good detection of methylene blue 0.1 μM.

Modified auto-combustion synthesis of mixed-oxides TiO2/NiO nanoparticles: Physical properties and photocatalytic performance

TiO2/NiO 50:50 wt % mixed-oxide nanopowders were successfully synthesized by a modified combustion based process. The effects of the synthesis condition, i.e. the pH of the starting solutions and the presence of the hydrogen peroxide (H2O2) as an oxidant, on the physical and structural characteristics of the synthesized nanopowders were evaluated. X-ray diffraction patterns (XRD) indicated that TiO2/NiO 50:50 wt % mixed-oxide nanopowders could be successfully synthesized through the combustion process in both acidic and alkaline conditions. XRD characteristic peaks of the TiO2 phase were intensified when H2O2 was used as the oxidant. The result of the dynamic light scattering (DLS) analysis showed that TiO2 and NiO powders, as well as the mixed-oxide samples synthesized at the alkaline condition, had very fine particle size distributions. The result of the scattering electron microscopy (SEM) demonstrated that the morphology of the combusted particles was affected by the molar ratios of TiO2/NiO and the pH of the synthesis process. UV–visible spectroscopy results implied that single-oxide NiO, TiO2, and TiO2/NiO mixed-oxide nanoparticles had narrow band gap values of 1.8, 2.6 and 2.5 eV, respectively. Zeta potential of the combusted mixed oxide nanoparticles was -28 mV. Adsorption-desorption isotherm of the as-prepared powders showed the formation of porous powders with a specific surface area of 19, 22, and 192 m2/g for NiO, TiO2, and TiO2/NiO particles, respectively. Results of the photocatalytic experiments under daylight emission using methylene blue (MB) as the dye molecule showed that degradation percentage of MB was more than 90% for all synthesized nanopowders. The small particle size, presence of the residual organics and narrow band gap energy were the leading factors which improved photocatalytic activity of the synthesized nanoparticles.

Biophysical Characterization of Membrane Phase Transition Profiles for the Discrimination of Outer Membrane Vesicles (OMVs) From Escherichia coli Grown at Different Temperatures

Dynamic Light Scattering (DLS), Small Angle X-ray Scattering (SAXS) and Transmission Electron Microscopy (TEM) are physical techniques widely employed to characterize the morphology and the structure of vesicles such as liposomes or human extracellular vesicles (exosomes). Bacterial extracellular vesicles are similar in size to human exosomes, although their function and membrane properties have not been elucidated in such detail as in the case of exosomes. Here, we applied the above cited techniques, in synergy with the thermotropic characterization of the vesicles lipid membrane using a turbidimetric technique to the study of vesicles produced by Gram-negative bacteria (Outer Membrane Vesicles, OMVs) grown at different temperatures. This study demonstrated that our combined approach is useful to discriminate vesicles of different origin or coming from bacteria cultured under different experimental conditions. We envisage that in a near future the techniques employed in our work will be further implemented to discriminate complex mixtures of bacterial vesicles, thus showing great promises for biomedical or diagnostic applications.

Comparative study on the new-old mortar interface deterioration after wet-dry cycles and heat-cool cycles

A well-bonded interface between concrete substrate and repair materials is of great significance for the durable repaired concrete. In this paper, the performance of the new-old mortar interface and deteriorations after wet-dry or heat-cool cycles were investigated by mechanical tests and microstructural analyses. Slant shear test, four-point bending strength test, back scattering electron microscopy (BSEM), microhardness test and thermogravimetric analysis (TGA) were carried out to characterize the interface deterioration. The results show that the slant shear test is suitable for evaluating the new-old mortar bond strength. The constituents of repair mortars affect the bond strength, but have little impact on the bending strength of composite beams. After cycled treatments, coupled effect of wet-dry and heat-cool cycles result in severer deteriorations of new-old mortar interface than heat-cool cycles do. Effect of heat-cool cycles is mainly attributed to reduction of interlocking point, while reductions in both interlocking point and chemical bond force are responsible for the interface deterioration after coupled cycles. The microstructural analyses further reveal the characterization of the new-old interface zone.

Micellar Fd3m cubosomes from monoolein – long chain unsaturated fatty acid mixtures: Stability on temperature and pH response

HypothesisControl of the nanostructure of self-assembled systems may be achieved through manipulation of surfactant molecular packing and interfacial curvature. In order to phase engineer the inverse micellar cubosomes in some monoolein-fatty acid systems, lipids with wedge shaped molecular geometry were incorporated to promote the formation of this phase, that is of interest as potential sustained released nanocarriers. ExperimentsLiquid crystalline nanoparticle dispersions of monoolein with some cis unsaturated fatty acids were prepared and their partial temperature-composition phase diagrams and structure were established using high throughput Small Angle X-ray Scattering (SAXS) and cryogenic transmission electron microscopy (cryo-TEM). The pH responsiveness of these systems was evaluated in the presence of phosphate buffered saline (PBS). FindingsThe partial temperature-composition phase diagrams of five nanoparticle formulations containing monoolein and unsaturated fatty acids were established and identified the presence of micellar cubosomes in each of these systems. The results indicate that temperature, fatty acid concentration and structure, as well as pH all directly impact the formation and stability of this phase. Low energy inverse micellar cubic to emulsion phase transformations were identified in the monoolein with oleic acid and vaccenic acid systems at physiological temperatures that may be advantageous for staged therapeutic release strategies in nanomedicine.

Fabrication of H2S Gas Sensor Based on Ppy/CuO and Ppy/SnO2 Nanocomposites at Room Temperature

The existence of Hydrogen sulfide (H2S) during the petroleum production and its high risks is the main reason to develop a smart, cheap and flexible device for H2S monitoring. This article is focusing on developing electrochemical sensors, which seems to have a promising potential. Polypyrrole (Ppy) and its two composites were prepared; Ppy doped with Cupper oxide (CuO) nanoparticles (Ppy/CuO) and Ppy doped with Tin oxide (SnO2) nanoparticles (Ppy/SnO2) via in-situ polymerization approach. The characterizations of these nanocomposites were confirmed by Fourier Transform Infrared spectroscopy (FTIR), X-ray diffraction (XRD), Dynamic Light Scattering (DLS) and High-Resolution Transition Electron Microscopy (HR-TEM). The testing of these nanocomposites towards the monitoring of H2S gas at different concentrations was carried out in the term of electrical resistance changes. From the data; it was found that the response at 1000 ppm H2S gas concentration was ranked as; Ppy 0.12 %. Ppy/CuO 4.7 %. Ppy/SnO2 53.2 %.

LSPR-based colorimetric immunosensor for rapid and sensitive 17β-estradiol detection in tap water

We propose a highly sensitive immunosensor based on the Localized Surface Plasmon Resonance (LSPR) for 17β-estradiol (E2) quantification in water. E2 molecules are recognized by polyclonal antibodies immobilized onto gold nanoparticles (AuNPs) and act as linkers that cause nanoparticles aggregation. This leads to the change in the optical properties of the solution visible even by naked eyes. The aggregates were characterized by Dynamic Light Scattering (DLS) and Scanning Transmission Electron Microscopy (STEM) that provided an accurate assessment of the inter-particle distance. The finite-difference time-domain (FDTD) method applied to a Mie problem like workspace allowed us to describe the optical behaviour of the AuNP aggregates with excellent agreement between the experimental and numerical results. The limit of detection (LOD), without any preconcentration step, is 3 pg/mL (11 pM), whereas the detection range extends over five decades up to 105 pg/mL. The proposed E2 immunosensor was tested in tap water, where no significant cross-reaction signal was detected by similar molecules (testosterone, progesterone, estrone and estriol). The device described here represents a significant improvement of low E2 levels determination in terms of affordability, time and measuring simplicity, making it suitable for environmental applications.

Comparison of pore evolution for a Mesoproterozoic marine shale and a Triassic terrestrial mudstone during artificial maturation experiments

Semi-closed pyrolysis experiments were performed on a Mesoproterozoic Hongshuizhuang marine shale sample and a Triassic Chang 7 terrestrial mudstone sample, in order to understand the mechanisms of pore evolution in shales with similar organic geochemical characteristics in different depositional environments. The pore characteristics of the solid samples from the thermal maturation experiments were investigated by low-pressure gas (N2 and CO2) sorption isotherms tests and Field Emission - Scattering Electron Microscopy (FE-SEM) imaging. Results indicate the marine shale samples develop more micropores than that of the terrestrial mudstone samples during the artificial maturation. Secondary organic pores are observed in the unheated samples (~0.76% EqRo) for the marine shale, which is earlier than that of in the terrestrial mudstone (observed in the sample at 250 °C, ~0.8% Ro). Significant development of organic pores at 350 °C for both the two shales. And the transformation of smaller pores into larger pores takes place at 450 °C for the marine shale, as well as for the terrestrial mudstone. In highly overmatured shales, the overpressure formed by organic matter cracking to gas can make surrounding interparticle space to vanish. The high content of rigid minerals in the marine shale is more conducive to the preservation of organic pores than the terrestrial mudstone with rich in ductile clay minerals. Therefore, pore increases continuously for the marine shale but decreases for the terrestrial mudstone after 500 °C. Micropores would be generated if a high lithostatic pressure exists under experimental conditions, which may be largely responsible for the disagreement of pore evolution of similar shales in other publications. Finally, a conceptual model of pore evolution for type-II marine and terrestrial shales is proposed. The study reveals that the pore evolution of shales with different sedimentary environments is divergent, and this need to be separately considered in the future work.

Physical-Chemical Study of Anthracene Selective Oxidation by a Fe(III)-Phenylporhyrin Derivative.

In this work, we studied the anthracene oxidation by hydroxyl radicals. Hydroxyl radical was generated by reaction of 5,10,15,20-tetrakis(4-carboxyphenyl)porphyrin Fe (III) (TPPFe) with hydrogen peroxide under visible radiation at a nitrogen atmosphere. The TPPFe was synthesized by Adler Method followed by metal complexation with Fe (III) chloride hexahydrate. Hydroxyl radical was detected by fluorescence emission spectroscopy and we studied kinetic of anthracene selective oxidation by hydroxyl radicals through the differential method. The TPPFe was characterized by UV-Vis spectrophotometry, Dynamic Light Scattering (DLS) and Scanning Electron Microscopy (SEM) measurements. The results indicated that TPPFE was compound by micro-particles with a size distribution of around 2500 nm. Kinetic results showed that the apparent rate constant for the oxidation of anthracene increased exponentially on as temperature increases, furthermore, the activation energy for the Anthracene oxidation by hydroxyl radicals under visible irradiation was 51.3 kJ/mol. Finally, anthraquinone was the main byproduct generated after oxidation of anthracene by TPP-Fe under visible irradiation.

Microwave assisted synthesis of gold nanoparticles with Phyla nodiflora (L.) Greene leaves extract and its studies of catalytic reduction of organic pollutants

The synthesis of gold nanoparticles (AuNPs) has drawn attention over the past few years owing to their optical and physico-chemical properties. In this work, AuNPs were synthesized using Phyla nodiflora (L.) leaf extract by microwave irradiation method. This leaf extract act as reducing and stabilizing agent. The concentrations of Phyla nodiflora (L.) Greene leaf extract, HAuCl4 and duration of microwave irradiation were optimized for the better yield of AuNPs. The AuNPs formation was confirmed by different analytical techniques like UV–Vis spectrophotometry (UV), Fourier Transform Infrared Spectroscopy (FTIR), Dynamic Light Scattering (DLS), X-Ray Diffraction (XRD) and Transmission Electronic Microscopy (TEM). Under the optimal synthetic conditions, the average diameter and zeta potential of AuNPs synthesized were 10 ± 2 nm and −24.0 mV respectively. Phytochemicals present in the extract help to reduce Au+3 to Au0 and act as a stabilizer in the synthesis of AuNPs. Afterwards, the catalytic activity of AuNPs was studied in NaBH4 assisted reduction of p-nitrophenol (4-NP), Congo Red (CR) and Methylene Blue (MB). Thus, AuNPs synthesized with leaf extract could be an excellent catalyst for 4-NP, CR and MB in chemical industries.

Structure-property relationships of d-mannitol-based cationic poly(amide triazoles) and their self-assembling complexes with DNA

A set of poly(amide triazoles) (PT) was synthesized by azide-alkyne cycloaddition reactions from N,N-Bis[2-(propargylamido)ethyl]-N-[2-(tert-butoxycarbonylamino)ethyl] amine and 1,6-diazido-1,6-dideoxy-d-mannitol derivatives, having the secondary hydroxyl groups protected by removable acetal and/or acetyl groups. Either copper-catalyzed (CuAAC) as well as the classical thermal cycloaddition reactions were used to afford in good yields and medium molecular weight-linear PT featuring either 1,4- or 1,4/1,5-disubstituted triazole rings along the polymer chains, respectively. Full structural characterization of all PT was accomplished and comparatively studied. Protecting group removal allowed for modulating the flexibility and polarity of cationic polytriazoles (CP), entitling for structure-activity relationship insight of their self-assembling capabilities in the presence of nucleic acids. Hence, CP and DNA were formulated at different nitrogen-to-phosphate (N/P) ratios and the resulting polyplexes were characterized by Dynamic Light Scattering (DLS) and Transmission Electron Microscopy (TEM). All CP were able to condense DNA into positively-charged nanometric-sized and narrow-polydispersed particles that could mediated transfection into human embryonic stem cells (hESC) with negligible toxicity.

Use of Pluronic P103 Triblock Copolymer as Structural Agent during Synthesis of Hybrid Silver Nanoparticles

Dilute aqueous solutions of triblock copolymer Pluronic P103 were used to synthesize silver nanoparticles (Ag-NPs) by chemical reduction of silver nitrate (AgNO3) with sodium borohydride (NaBH4). This copolymer was used as a structural agent since monomers act as a stabilizer and micelles act as nanoreactors for nucleation and growth of Ag-NPs. The growth of the nanoparticles (NPs) was monitored by UV-visible spectroscopy on the basis of measuring surface plasmon resonance absorption over a temperature range of 25 to 70°C. Shape and size of hybrid silver/P103 nanomaterials were tuned by varying the micellar structure of Pluronic P103 using a simple synthesis procedure. Dynamic Light Scattering (DLS) and Transmission Electron Microscopy (TEM) were used to study the size and shape of the hybrid nanomaterials. It was observed that Ag-NPs synthesized without Pluronic P103 at 25°C exhibited a great variety of sizes. However, when Pluronic P103 was used below its critical micellar concentration (CMC), spherical-shaped Ag-NPs with uniform size were formed, suggesting that the copolymer had a stabilizing effect. On the other hand, when Ag-NPs were prepared with Pluronic P103 above the CMC, NPs with similar sizes as the micelles were detected, suggesting that the copolymer functioned as a nanoreactor. Furthermore, as temperature reached 35°C, oval-shaped micelles were formed and small NPs were incorporated into the crown of the micelles. Independent Ag-NPs were not observed since they used the surface of the micelles as a soft template. Therefore, it was possible to obtain tiny Ag-NPs with homogeneous size.

Revealing the Influence of the Degumming Process in the Properties of Silk Fibroin Nanoparticles.

Several studies have stated that the process used for sericin removal, or degumming, from silk cocoons has a strong impact in the silk fibroin integrity and consequently in their mechanical or biochemical properties after processing it into several biomaterials (e.g. fibers, films or scaffolds) but still, there is a lack of information of the impact on the features of silk nanoparticles. In this work, silk cocoons were degummed following four standard methods: autoclaving, short alkaline (Na2CO3) boiling, long alkaline (Na2CO3) boiling and ultrasounds. The resultant silk fibroin fibers were dissolved in the ionic liquid 1-ethyl-3-methylimidazolium acetate and used for nanoparticle synthesis by rapid desolvation in polar organic solvents. The relative efficiencies of the degumming processes and the integrity of the resulting fibroin fibers obtained were analyzed by mass loss, optical microscopy, thermogravimetric analysis, infrared spectroscopy and SDS-PAGE. Particle sizes and morphology were analyzed by Dynamic Light Scattering and Field Emission Scanning Electronic Microscopy. The results showed that the different treatments had a remarkable impact on the integrity of the silk fibroin chains, as confirmed by gel electrophoresis, which can be correlated with particle mean size and size distribution changes. The smallest nanoparticles (156 ± 3 nm) and the most negative Z potential (−30.2 ± 1.8 mV) were obtained with the combination of long treatment (2 h) of boiling in alkaline solution (Na2CO3 0.02 eq/L). The study confirms that parameters of the process, such as composition of the solution and time of the degumming step, must be controlled in order to reach an optimum reproducibility of the nanoparticle production.

Catalytic conversion of 5-hydroxymethylfurfural (5-HMF) over Pd-Ru/FAU zeolite catalysts

We present this study on FAU-type zeolites were prepared varying the Si/Al ratio (4, 5 and 6) and crystallization time (4, 6 and 8 h) to produce a highly pure and homogeneous material with enhanced surface area values. Bimetallic Pd-Ru and Pt-Ru (0.5 wt.% of each metal) were impregnated onto the zeolites matrix by the incipient wetness impregnation method. The materials were characterized by X-ray diffraction (XRD), nitrogen physisorption, Fourier Transform Infrared spectroscopy (FT-IR), Scattering Electronic Microscopy (SEM), Scattering and Transmission Microscopy (STEM), temperature-programmed desorption (TPD), temperature-programmed desorption (TPR) and Inductively Couples Plasma- Mass Spectrometer (ICP-MS). Results indicated that using lower Si/Al ratios favored the catalytic activity. Also, the longest crystallization time had a positive effect on surface area, homogeneous particle size distribution and crystallinity. The catalytic performance in the esterification of 5-hydroxymethylfurfural (5-HMF) to produce 5-acetoxymethylfurfural (AcMF) was investigated. The maximum 5-HMF conversion of 87.28 % was achieved using pure zeolite with relation Si/Al = 5, and 8 h of crystallization. Pd-Ru supported onto same zeolite showed a conversion of 84.22 %. The highest selectivity towards AcMF of 71.29 % with pure zeolite Si/Al = 5 and 8 h of crystallization was achieved, followed by Pd-Ru/FAU with Si/Al = 5 and 8 h of crystallization, achieving 60.42 %. Finally, results shown that the interaction between the properties of zeolitic support and the metallic species, specifically Pd, had a positive effect in the catalytic process the pristine zeolite showed improved catalytic characteristics related to its acid strength.

Understanding the interaction between Soluplus® and biorelevant media components

Soluplus® (polyvinyl caprolactam-polyvinyl acetate-polyethylene glycol graft copolymer) is a solubilizing copolymer commonly applied as carrier in solid dispersions of poorly soluble drugs. This polymer is used to increase the apparent solubility of drugs with low aqueous solubility and consequently enhance drug absorption by the human gastrointestinal tract. To select the appropriate carrier to compose solid dispersions, in vitro supersaturation studies were applied as a pre-formulation tool, using different dissolution media. During in vitro supersaturation studies performed for the poorly soluble drug candesartan cilexetil, it was found that Soluplus® may interact with components of the biorelevant medium Fasted State Simulated Intestinal Fluid, lowering the drug apparent solubility. Dynamic Light Scattering and Transmission Electron Microscopy analyses were performed, as well as fluorescence measurements, aiming to characterize the interaction behavior and determine the polarity of the microenvironment. It was evidenced that Soluplus® interacted preferentially with lecithin, forming mixed micelles with a more polar microenvironment, which lowered the candesartan cilexetil solubilization capacity and consequently reduced its apparent solubility in the biorelevant medium. These findings are important to emphasize the key role of the media selection for in vitro solubility-supersaturation studies, where media that could mimic the human gastrointestinal environment are recommended.

Determination of the size dispersion of amorphous silicon quantum dots from a silicon nitride film containing silicon nanocrystals

In this work we will investigate the size distribution of the amorphous silicon quantum dots (Si-AQD) inside a silicon nitride film SiNx (x = 0.12). The studied film contains an ensemble of silicon nanocrystals (Si-nc) inside an amorphous silicon nitride matrix SiNy (y = 0.66). Since the nitrogen atoms number are less than the silicon atoms number in the amorphous matrix, we can suggest that silicon atoms can aggregate under amorphous quantum dots. In this context, we will first estimate the number of crystallized silicon atoms (c-Si). The number of amorphous silicon atoms (a-Si) can be deduced from the fraction of crystallized silicon atoms and leads to the determination of the number of nitrogen atoms.Results show that all the nitrogen atoms are localized in the Si-ncs cap shell. Thus, the amorphous quantum dots can be easily revealed from the scattering electron microscopy (SEM) image. The low yield of luminescence from amorphous quantum dots can explain the difference between both experimental and simulated photoluminescence (PL) from silicon nitride film containing Si-ncs.

Preparation of Highly Porous PAN-LATP Membranes as Separators for Lithium Ion Batteries.

Separators are a vital component to ensure the safety of lithium-ion batteries. However, the commercial separators employed in lithium ion batteries are inefficient due to their low porosity. In the present study, a simple electrospinning technique is adopted to prepare highly porous polyacrylonitrile (PAN)-based membranes with a higher concentration of lithium aluminum titanium phosphate (LATP) ceramic particles, as a viable alternative to the commercialized separators used in lithium ion batteries. The effect of the LATP particles on the morphology of the porous membranes is demonstrated through Field emission scattering electron microscopy. X-ray diffraction and Fourier transform infrared spectra studies suitably demonstrate the mixing of PAN and LATP particles in the polymer matrix. PAN with 30 wt% LATP (P-L30) exhibits an enhanced porosity of 90% and is more thermally stable, with the highest electrolyte uptake among all the prepared membranes. Due to better electrolyte uptake, the P-L30 membrane demonstrates an improved ionic conductivity of 1.7 mS/cm. A coin cell prepared with a P-L30 membrane and a LiFePO4 cathode demonstrates the highest discharge capacity of 158 mAh/g at 0.5C rate. The coin cell with the P-L30 membrane also displays good cycling stability by retaining 87% of the initial discharge capacity after 200 cycles of charging and discharging at 0.5C rate.

Poly(ethylene Glycol) Diacrylate-Nanogels Synthesized by Mini-emulsion Polymerization

New nanogels (NGs) with tailored properties were obtained using a mini-emulsion technique, from poly(ethylene glycol) diacrylate (PEGDA) self-crosslinking macromers of various molecular weight. By modifying synthesis parameters (hydrophilic-lipophilic balance, emulsifier and the ratio of organic-aqueous medium), optimum recipes of NGs were selected. Therefore, the molecular weight distribution and the functionalization degree of the PEGDA2000 macromer were assessed by Gel Permeation Chromatography (GPC) and Nuclear Magnetic Resonance (NMR), respectively. Furthermore, the PEGDA-NGs were investigated by Dynamic Light Scattering (DLS) and Transmission Electron Microscopy (TEM) for size distributions and morphology. DLS and TEM results confirm that these new PEGDA-NGs hold potential for biomedical applications.