Emerging Mesoporous Polyacrylamide/Gelatin-Iron Lanthanum Oxide Nanohybrids towards the Antibiotic Drugs Removal from the Wastewater.

The polyacrylamide/gelatin-iron lanthanum oxide (P-G-ILO nanohybrid) was fabricated by the free radical grafting co-polymerization technique in the presence of N,N-methylenebisacrylamide (MBA) as cross linker and ammonium persulfate (APS) as initiator. The P-G-ILO nanohybrid was characterized by the various spectroscopic and microscopic techniques that provided the information regarding the crystalline behavior, surface area, and pore size. The response surface methodology was utilized for the statistical observation of diclofenac (DF) adsorption from the wastewater. The adsorption capacity (qe, mg/g) of P-G-ILO nanohybrid was higher (254, 256, and 258 mg/g) than the ILO nanoparticle (239, 234, and 233 mg/g). The Freundlich isotherm model was the best fitted, as it gives the higher values of correlation coefficient (R2 = 0.982, 0.991 and 0.981) and lower value of standard error of estimate (SEE = 6.30, 4.42 and 6.52), which suggested the multilayered adsorption of DF over the designed P-G-ILO nanohybrid and followed the pseudo second order kinetic model (PSO kinetic model) adsorption. The thermodynamic study reveals that adsorption was spontaneous and endothermic in nature and randomness onto the P-G-ILO nanohybrids surface increases after the DF adsorption. The mechanism of adsorption of DF demonstrated that the adsorption was mainly due to the electrostatic interaction, hydrogen bonding, and dipole interaction. P-G-ILO nanohybrid was reusable for up to five adsorption/desorption cycles.

Colossal Permittivity Characteristics of (Nb, Si) Co-Doped TiO2 Ceramics.

(Nb5+, Si4+) co-doped TiO2 (NSTO) ceramics with the compositions (Nb0.5Si0.5)xTi1−xO2, x = 0, 0.025, 0.050 and 0.1 were prepared with a solid-state reaction technique. X-ray diffraction (XRD) patterns and Raman spectra confirmed that the tetragonal rutile is the main phase in all the ceramics. Additionally, XRD revealed the presence of a secondary phase of SiO2 in the co-doped ceramics. Impedance spectroscopy analysis showed two contributions, which correspond to the responses of grain and grain-boundary. All the (Nb, Si) co-doped TiO2 showed improved dielectric performance in the high frequency range (>103 Hz). The sample (Nb0.5Si0.5)0.025Ti0.975O2 showed the best dielectric performance in terms of higher relative permittivity (5.5 × 104) and lower dielectric loss (0.18), at 10 kHz and 300 K, compared to pure TiO2 (1.1 × 103, 0.34). The colossal permittivity of NSTO ceramics is attributed to an internal barrier layer capacitance (IBLC) effect, formed by insulating grain-boundaries and semiconductor grains in the ceramics.

Dielectric Properties of Bi2/3Cu3Ti4O12 Ceramics Prepared by Mechanical Ball Milling and Low Temperature Conventional Sintering.

In the current study, Bi2/3Cu3Ti4O12 (BCTO) ceramics were prepared by mechanical ball mill of the elemental oxides followed by conventional sintering of the powder without any pre-sintering heat treatments. The sintering temperature was in the range 950-990 °C, which is 100-150 °C lower than the previous conventional sintering studies on BCTO ceramics. All the ceramic samples showed body-centered cubic phase and grain size ≈ 2-6 µm. Sintering temperature in the range 950-975 °C resulted in comparatively lower dielectric loss and lower thermal coefficient of permittivity in the temperature range from -50 to 120 °C. All the BCTO ceramics showed reasonably high relative permittivity. The behavior of BCTO ceramics was correlated with the change in oxygen content in the samples with sintering temperature. This interpretation was supported by the measurements of the energy dispersive x-ray spectroscopy (EDS) elemental analysis and activation energy for conduction and for relaxation in the ceramics.

Sintering Temperature, Frequency, and Temperature Dependent Dielectric Properties of Na0.5Sm0.5Cu3Ti4O12 Ceramics.

NSCTO (Na0.5Sm0.5Cu3Ti4O12) ceramics have been prepared by reactive sintering solid-state reaction where the powder was prepared from the elemental oxides by mechanochemical milling followed by conventional sintering in the temperature range 1000-1100 °C. The influence of sintering temperature on the structural and dielectric properties was thoroughly studied. X-ray diffraction analysis (XRD) revealed the formation of the cubic NSCTO phase. By using the Williamson-Hall approach, the crystallite size and lattice strain were calculated. Scanning electron microscope (SEM) observations revealed that the grain size of NSCTO ceramics is slightly dependent on the sintering temperature where the average grain size increased from 1.91 ± 0.36 µm to 2.58 ± 0.89 µm with increasing sintering temperature from 1000 °C to 1100 °C. The ceramic sample sintered at 1025 °C showed the best compromise between colossal relative permittivity (ε' = 1.34 × 103) and low dielectric loss (tanδ = 0.043) values at 1.1 kHz and 300 K. The calculated activation energy for relaxation and conduction of NSCTO highlighted the important role of single and double ionized oxygen vacancies in these processes.

Dielectric Response and Structural Analysis of (A3+, Nb5+) Cosubstituted CaCu3Ti4O12 Ceramics (A: Al and Bi).

CaCu3Ti4-x((A0.05Nb0.05))xO12 ceramics (A: Al and Bi; x = 0, 0.3) were synthesized by high-energy mechanical ball milling and reactive sintering at 1050 °C in air. Rietveld refinement of XRD data revealed the pure and (Al3+, Nb5+) cosubstituted ceramics contained a minor CuO secondary phase with a mole fraction of about 3.2% and 6.9%, respectively, along with a CaCu3Ti4O12 (CCTO)-like cubic structure. In addition, (Bi3+, Nb5+) cosubstituted ceramics had a pyrochlore (Ca2(Ti, Nb)2O7) secondary phase of about 18%. While the (Al3+, Nb5+) cosubstituted CCTO showed the highest relative permittivity (ε' = 3.9 × 104), pure CCTO showed the lowest dielectric loss (tanδ = 0.023) at 1 kHz and 300 K. Impedance-spectroscopy (IS) measurements showed an electrically heterogeneous structure for the studied ceramics, where a semiconducting grain was surrounded by highly resistive grain boundary. The giant relative permittivity of the ceramics was attributed to the Maxwell-Wagner polarization effect at the blocking grain boundaries and domain boundaries. The higher tanδ of the cosubstituted samples was correlated with their lower grain boundary's resistivity, as confirmed by IS analysis. Modulus-spectrum analysis revealed two relaxation processes for the pure and (Bi3+, Nb5+) cosubstituted CCTO samples. Dissimilar behavior was observed for the (Al3+, Nb5+) cosubstituted CCTO, where three relaxation mechanisms were observed and attributed to the grain, domain-boundary, and grain-boundary responses.

Origin of the enhanced Li(+) ionic conductivity in Gd(+3) substituted Li5+2xLa3Nb2-xGdxO12 lithium conducting garnets.

In the present study, we report the synthesis and the Li(+)-ion conductivity of new Gd(+3) substituted Li5+2xLa3Nb2-xGdxO12 (x = 0.0, 0.25, 0.4, 0.5, 0.6) garnets. The structural study by XRD showed that pure cubic garnet phases were obtained with upto x = 0.5 composition. With the further increase of the Gd(+3) content to x≥ 0.6, secondary phases are observed. The ionic conductivity was studied by impedance spectroscopy. We found that the Li(+) ionic conductivity increased with increasing Gd(+3) content with a maximum value of 1.12 × 10(-4) S cm(-1) at RT, which was two orders of magnitude larger than the previously reported value of 10(-6) S cm(-1) for pure Li5La3Nb2O12. A slight drop in the conductivity value to 6.25 × 10(-5) S cm(-1) was observed for x = 0.6 composition. By a systematic analysis of the conductivity spectra at different temperatures of the investigated materials, we are able to estimate the true values of the concentration, nc, and mobility, µ, of mobile Li(+) that contribute to the conduction process; nc was found to increase by a factor of only ∼2 with increasing Gd(+3) content from x = 0.0 to x = 0.5, whereas the mobility/diffusivity of Li(+) increased considerably with increasing Gd(+3) content. Therefore, the enhanced conductivity of the current materials is mainly due to the enhanced mobility of Li(+). Surprisingly, the fraction of mobile Li(+) represents only 3.44-6.96% of the total Li(+) density of the materials.

Lithium ionic conduction and relaxation dynamics of spark plasma sintered Li5La3Ta2O12 garnet nanoceramics.

In the present work, nanoceramics of Li5La3Ta2O12 (LLT) lithium ion conductors with the garnet-like structure are fabricated by spark plasma sintering (SPS) technique at different temperatures of 850°C, 875°C, and 900°C (SPS-850, SPS-875, and SPS-900). The grain size of the SPS nanoceramics is in the 50 to 100 nm range, indicating minimal grain growth during the SPS experiments. The ionic conduction and relaxation properties of the current garnets are studied by impedance spectroscopy (IS) measurements. The SPS-875 garnets exhibit the highest total Li ionic conductivity of 1.25 × 10(-6) S/cm at RT, which is in the same range as the LLT garnets prepared by conventional sintering technique. The high conductivity of SPS-875 sample is due to the enhanced mobility of Li ions by one order of magnitude compared to SPS-850 and SPS-900 ceramics. The concentration of mobile Li(+) ions, n c, and their mobility are estimated from the analysis of the conductivity spectra at different temperatures. n c is found to be independent of temperature for the SPS nanoceramics, which implies that the conduction process is controlled by the Li(+) mobility. Interestingly, we found that only a small fraction of lithium ions of 3.9% out of the total lithium content are mobile and contribute to the conduction process. Moreover, the relaxation dynamics in the investigated materials have been studied through the electric modulus formalism.

Hopping rates and concentrations of mobile fluoride ions in Pb(1-x)Sn(x)F(2) solid solutions.

In the present paper, the ion dynamics and relaxation of fluoride ions in Pb(1-x)Sn(x)F(2) (with x=0.2-0.6) solid solutions, prepared by mechanochemical milling, are studied in the conductivity formalism over wide ranges of frequencies and temperatures. The conductivity spectra of the investigated materials are analyzed by the Almond-West (AW) power-law model. The estimated values of the hopping rates and the dc conductivity of different compositions are thermally activated with almost the same activation energy. The calculated values of the concentration of mobile ions, n(c), are almost independent of temperature and composition for x=0.2-0.4. The maximum value of n(c) is obtained for the x=0.6 sample, although it does not show the maximum conductivity. Therefore, the composition dependence of the ionic conductivity of these solid solutions could be explained based on the extracted parameters. The results presented in the current work indicate that the AW model represents a reasonable approximation of the overall frequency-dependent conductivity behavior of the investigated materials. The conductivity spectra at different temperatures for each composition are successfully scaled to a single master curve, indicating a temperature-independent relaxation mechanism. For different compositions, however, the conductivity spectra cannot be scaled properly, indicating composition-dependent relaxation dynamics.

Contribution of nitric oxide and epidermal growth factor receptor in anti-metastatic potential of paclitaxel in human liver cancer cell (HebG2).

BACKGROUND: Paclitaxel is a general antineoplastic drug used against different types of experimental and human tumors. Several anti-cancer drugs have been shown to stimulate nitric oxide (NO) production, which has been shown to affect many aspects of tumor biology. OBJECTIVE: This study was initiated to determine if paclitaxel stimulates NO production in HebG2 cells, and if so, whether NO interferes with the metastatic potential of HebG2 cells and contributes to paclitaxel cytotoxicity. In addition, we sought to determine the relationship between NO production and the expression of epidermal growth factor receptor (EGFR) and matrix metaloproteinases (MMPs) in HebG2 cells. MATERIALS AND METHODS: The effects of paclitaxel (0.1-1000 nM) on surviving fraction, NO production and the expression of EGFR, MMP-2 and MMP-9 were studied in human liver cancer cells (HebG2). RESULTS: Paclitaxel resulted in a significant dose dependent decrease in the surviving fraction of HebG2 cells. A 62% and 86% decrease in the surviving fraction was attained at 10nM and 100 nM paclitaxel, respectively. Paclitaxel produced a significant increase in NO production, starting from 1 nM. A 64% and 111% increase in NO production was attained after exposure to 10nM and 100 nM of paclitaxel, respectively. In all of the HebG2 cells treated with paclitaxel (1.0-1000 nM) mRNA specific for EGFR, MMP-2 and MMP-9 were undetectable. However, untreated HebG2 cells and those treated with paclitaxel (0.1 nM) expressed mRNA specific for these markers. CONCLUSION: This study suggests that: (1) increased production of NO may contribute to paclitaxel's cytotoxicity against HebG2 cells, (2) paclitaxel may inhibit tumor metastasis via inhibition of the expression of EGFR and MMPs and (3) an inverse correlation exist between NO production and expression of EGFR and MMPs.