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Strongly enhanced tunable photoluminescence in polymorphous silicon carbon thin films via excitation-transfer mechanism

Here, we investigate the enhanced tunable photoluminescence (PL) of hydrogenated polymorphous silicon carbon (pm-Si1−xCx:H) thin films fabricated in a plasma enhanced chemical vapor deposition system. The silicon nanocrystal (nc-Si) inclusions are formed during gas-phase nucleation and incorporated in the hydrogenated amorphous silicon carbon (a-SiC:H) matrix. The nc-Si provides high-quality recombination centers for the photogenerated carriers in the pm-Si1−xCx:H material, while the a-SiC:H matrix plays a role of sensitizer. We elucidate and provide experimental evidence for this excitation-transfer mechanism. Strongly enhanced PL performance can be achieved by effective matrix passivation that favors a diffusion-driven carrier recombination in the nc-Si centers.

Further Insight into the Definite Morphology and Formation Mechanism of Mesoporous Silica KCC-1

The unique three-dimensional pore structure of KCC-1 has attracted significant attention and has proven to be different compared to other conventional mesoporous silica such as the MCM-41 family, SBA-15, or even MSN nanoparticles. In this research, we carefully examine the morphology of KCC-1 to define more appropriate nomenclature. We also propose a formation mechanism of KCC-1 based on our experimental evidence. Herein, the KCC-1 morphology was interpreted mainly on the basis of compiling all observation and information taken from SEM and TEM images. Further analysis on TEM images was carried out. The gray value intensity profile was derived from TEM images in order to determine the specific pattern of this unique morphology that is found to be clearly different from that of other types of porous spherical-like morphologies. On the basis of these results, the KCC-1 morphology would be more appropriately reclassified as bicontinuous concentric lamellar morphology. Some physical characteristics such as the origin of emulsion, electrical conductivity, and the local structure of water molecules in the KCC-1 emulsion were disclosed to reveal the formation mechanism of KCC-1. The origin of the KCC-1 emulsion was characterized by the observation of the Tyndall effect, conductometry to determine the critical micelle concentration, and Raman spectroscopy. In addition, the morphological evolution study during KCC-1 synthesis completes the portrait of the formation of mesoporous silica KCC-1.

Intermolecular Interactions and the Release Pattern of Electrospun Curcumin-Polyvinyl(pyrrolidone) Fiber

An electrospun fiber of polyvinyl(pyrrolidone) (PVP)-Tween 20 (T20) with curcumin as the encapsulated drug has been developed. A study of intermolecular interactions was performed using Raman spectroscopy, Fourier transform infrared (FT-IR), differential scanning calorimetry (DSC), and X-ray diffraction (XRD). The Raman and FT-IR studies showed that curcumin preferrably interacted with T20 and altered PVP chain packing, as supported by XRD and physical stability data. The hydroxyl stretching band in PVP shifted to a lower wavenumber with higher intenstity in the presence of curcumin and PVP, indicating that hydrogen bond formation is more intense in a curcumin or curcumin-T20 containing fiber. The thermal pattern of the fiber did not indicate phase separation. The conversion of curcumin into an amorphous state was confirmed by XRD analysis. An in vitro release study in phosphate buffer pH 6.8 showed that intermolecular interactions between each material influenced the drug release rate. However, low porosity was found to limit the hydrogen bond-mediated release.

Further insights into the structural transformations in PbBi4Ti4O15 revealed by Raman spectroscopy

The structural transformations in PbBi4Ti4O15 (PBT) induced by decreasing the temperature from 850 to 120 K were investigated using Raman spectroscopy. The temperature evolution of phonon modes revealed structural alterations in PBT occurred near 800, 600, and 400 K. The paraelectric-ferroelectric phase transition at 800 K was clearly observed in the temperature behavior of the low-energy phonon mode at 60 cm−1 that has been previously attributed to a displacement of the Bi2O2 plane with respect to the Aurivillius perovskite-like block, emphasizing that this is the phonon mode driving the system into a ferroelectric state. The structural transformation near 600 K was identified from the mode at 40 cm−1 related to Pb/Bi vibrations in the perovskite-like block as well as modes at 130 and 220 cm−1 caused by octahedral tilting of TiO6. The temperature of this structural alteration matches the second anomaly observed in the dielectric permittivity of PBT, so it causes minor spontaneous polarization in this mat...

Intraoral Film Containing Insulin-Phospholipid Microemulsion: Formulation and In Vivo Hypoglycemic Activity Study

Non-invasive administration of insulin is expected for better diabetes mellitus therapy. In this report, we developed intraoral preparation for insulin. Insulin was encapsulated into nanocarrier using self-assembly emulsification process. To increase lipophilicity of insulin, it was dispersed in phospholipid resulted in insulin-phospholipid solid dispersion. The microemulsion formula was established from our previous work which contained glyceryl monooleate (GMO), Tween 20, and polyethylene glycol (PEG 400) in a ratio of 1:8:1. To confirm the formation of insulin-phospholipid solid dispersion, PXRD, FTIR spectroscopy, and Raman spectroscopy were performed. Then, the microemulsion was evaluated for droplet size and distribution, zeta potential, entrapment efficiency, physical stability, and Raman spectroscopy. In addition, microemulsion with expected characteristic was evaluated for in vitro release, in vitro permeation, and in vivo activity. The droplets size of ∼100 nm with narrow distribution and positive charge of +0.56 mV were formed. The insulin encapsulated in the oil droplet was accounted of >90%. Water-soluble chitosan seems to be a promising film matrix polymer which also functioned as insulin release controller. Oral administration of insulin microemulsion to healthy Swiss-Webster mice showed hypoglycemic effect indicating the success of this protein against a harsh environment of the gastrointestinal tract. This effectiveness significantly increased by fourfold as compared to free insulin. Taken together, microemulsion seems to be a promising carrier for oral delivery of insulin.

Effect of chitosan and chitosan-nanoparticles on post harvest quality of banana fruits

In this study, we evaluated the effect of different concentrations of chitosan and chitosan nanoparticles as edible coating in extending shelf life and maintaining the quality of banana fruits (Musa acuminata AAA group). The fruit treated with 1.15% chitosan, 1.25% chitosan and chitosan nanoparticles then store at ambient temperature (25±1°C). The shelf-life of banana, starch content, weight loss, pulp to peel ratio, total soluble solid, surface morpholgy of banana peel and sensory evaluation were analysed. Molecular analysis on the effect of chitosan was also conducted. Results showed that the application of chitosan nanoparticles and chitosan could extend shelf-life and maintain quality of banana fruits.

Temperature Dependent Raman Studies of Pr2Zr2O7 Single Crystal

The temperature-dependent Raman studies of Pr2Zr2O7 has been performed on single crystals samples in the temperature range from 80 K to 820 K. By using polarization measurement, the vibration modes of A1g, Eg, and 4T2g have been assigned on 295.9 cm-1, 497.3 cm-1, and 102.4 cm-1, 309.2 cm-1, 670.6 cm-1, 878 cm-1, respectively. The ambiguity vibration mode around 300 cm-1 in pyrochlore compounds can be resolved. The 380 cm-1 mode showed sharpening upon heating up from 370 K which support the present of Oxygen distortion towards vacant site.

Raman scattering study of the effect of A- and B-site substitution on the room-temperature structure of ABi4Ti4O15

Aurivillius-type materials exhibit promising ferroelectric and multiferroic properties that can be tailored via chemistry variations in the perovskite block. Hence, it is important to clarify the relations composition-structure, also on a local-scale level. The aim of this contribution is to give further insights into the effect of A- and B-site cations to the room-temperature local structure of Aurivillius four-layered ABi4Ti4O15 (A = Sr, Pb, Ba) and Pb1−x Bi4+x Ti4−x Mn x O15 (x = 0, 0.2, 0.4) by Raman scattering. The effect of A-site cation to the local structure of perovskite block was identified by the phonon mode near 750 and 870 cm−1 arising from BO6 stretching. A-site Ba2+, having the largest ionic radius among the considered elements, significantly stiffens the TiO6 octahedra, as derived from the fact that the TiO6 stretching modes have the highest wavenumber for BaBi4Ti4O15, i.e. the Ti-O bond strength is strongest for this compound. The replacement of Ti4+ by Mn3+ cation at the B- site also influences the B-O bond. The comparison of the phonon modes near 700 and 870 cm−1 in Pb1−x Bi4+x Ti4−x Mn x O15 with x = 0, 0.2, and 0.4 shows that the lowest wavenumber, which is due to the elongation of Ti-O bonds is observed for x = 0.4.

Polyaniline/Zn as secondary battery for electric vehicle base on energy return factor

Study on polyaniline (PANI) as a cathode in the PANI/Zn secondary battery has been performed. PANI was synthesized using electrodeposition method on the surface of the Graphite Sheets (GS), at 0.7 V relative to the saturated Ag/AgCl. PANI film was characterized by FT-IR spectroscopy, UV-Vis absorption, and Raman spectroscopy. And then the potential of using the PANI film as an electrodes was studied in a rechargeable battery system. This battery system consisted of GS|PANI|ZnCl2(electrolytes)|Zn configuration. Battery performance tests were carried out through the charge/discharge processes for 60 cycles at a current of 10 mA. The measurement results found that the performance of the battery at the first cycle of 59.49 mAh g−1, while at 60th cycle were 55.42 mAh g−1, and the percent capacity loss until the last cycle was 6.77%. Meanwhile, Energy Return Factor (ERF) of PANI/Zn battery until last cycle was increase compare to the first cycle approximately 83.82%. Impedance measurements PANI/Zn battery showed the solution resistance (Rs) were 1.38 Q, while for charge transfer resistance (Rct) were 2.24 Q.

Phonon Properties of Co:TiO2 Single Crystal

Phonon properties of cobalt doped rutile TiO2 single crystal was investigated using a Raman Spectrometer with laser wavelength at 532 nm in the temperature range from 140 K to 750 K. The phonons modes of B1g, Eg, and A1g with the energy of 140 cm-1, 450 cm-1 and 600 cm-1 are clearly observed. The second order phonon process is also observed at the energy of 250 cm-1. The temperature dependence of the A1g, Eg modes become stiffen as lowering the temperature, while the B1g mode becomes soften. The temperature dependence of the B1g is found to be a signature as the effect of doping. Based on the harmonic model, this is explained due to the change the Ti-O coupling strengths of TiO6 octahedral. A larger change is found for the longer distance of the Ti-O bond.