34 research outputs found
Cu(II) and Gd(III) doped boehmite nanostructures: a comparative study of electrical property and thermal stability
The present article reports the effect of transition (Cu2+) and rare earth metal (Gd3+) ion doping on structural, microstructural and electrical properties of boehmite nanoparticles. Rietveld refinement is adopted here to refine the x-ray diffractograms for further analyzing the microstructural details and their alteration due to the incorporation of foreign cations. This is probably the first time when dielectric properties of these doped boehmite samples having been reported herein. These samples show remarkably high dielectric constant values which corroborate that doping enhances the microstrain values inside the orthorhombic structure and results in higher crystallographic defects. Enhancement in defect sites causes the augmentation of relative permittivity and ac conductivity. Temperature stability has also been enhanced significantly in our Cu-doped sample. The present study enables us to determine a relationship between crystalline deformation and electrical properties of nanomaterials which may be highly beneficial in fabricating cost-effective energy harvesting devices
Stacking Order Driven Optical Properties and Carrier Dynamics in ReS2
Two distinct stacking orders in ReS2 are identified without ambiguity and
their influence on vibrational, optical properties and carrier dynamics are
investigated. With atomic resolution scanning transmission electron microscopy
(STEM), two stacking orders are determined as AA stacking with negligible
displacement across layers, and AB stacking with about a one-unit cell
displacement along the a axis. First-principle calculations confirm that these
two stacking orders correspond to two local energy minima. Raman spectra inform
a consistent difference of modes I & III, about 13 cm-1 for AA stacking, and 20
cm-1 for AB stacking, making a simple tool for determining the stacking orders
in ReS2. Polarized photoluminescence (PL) reveals that AB stacking possesses
blue-shifted PL peak positions, and broader peak widths, compared with AA
stacking, indicating stronger interlayer interaction. Transient transmission
measured with femtosecond pump probe spectroscopy suggests exciton dynamics
being more anisotropic in AB stacking, where excited state absorption related
to Exc. III mode disappears when probe polarization aligns perpendicular to b
axis. Our findings underscore the stacking-order driven optical properties and
carrier dynamics of ReS2, mediate many seemingly contradictory results in
literature, and open up an opportunity to engineer electronic devices with new
functionalities by manipulating the stacking order
Synthesis and biological evaluation of triphenyl-imidazoles as a new class of antimicrobial agents
Newer triphenyl-imidazole derivatives (4a-h) were synthesized in good yields by the reaction of benzil and substituted benzaldehydes in equimolar quantities and refluxing the product with acetyl chloride thereafter. Structures were confirmed by using FT-IR, 1H NMR and 13C NMR spectroscopic methods. All the synthesized compounds were tested for their antimicrobial activity using agar diffusion technique against Gram positive (Staphhylococcus aureus and Bacillus subtilis), Gram negative (Escherichia coli and Pseudomonas aureginosa) as well as Fungal strain (Candida albicans). Interestingly compounds 4a, 4b, 4f and 4h showed significant antibacterial activity, whereas compound 4b was found to have remarkable activity against the fungal strain. The Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) of most active compounds were determined by broth dilution method and compound 4b emerged to have potent activities against most of the strains having MIC in the range of 25-200 Āµg/mL. To check the possible toxicities of the most active compounds, they were orally administered in rats and the concentration of liver enzymes serum glutamic-oxaloacetic transaminase (SGOT), serum glutamic pyruvic transaminase (SGPT) and alkaline phosphatase (ALKP) were determined. Compound 4h showed significant increase in the enzymes level depicting the hepatotoxicity. The structure-activity relationship studies showed the importance of electron withdrawing groups at the distant phenyl ring at ortho and para positions as the compounds having chloro or nitro at these positions tend to be more active than the compounds with electron releasing groups such as methoxy. These compounds may act as lead compounds for further studies and appropriate modification in their structure may lead to agents having high efficacy with lesser toxicity
Analgesic and Anti-Inflammatory Activities of Quercetin-3-methoxy-4ā²-glucosyl-7-glucoside Isolated from Indian Medicinal Plant <i>Melothria heterophylla</i>
Background: Melothria heterophylla (family: Cucurbitaceae), commonly known as kudari, is used in the Indian traditional medicine to treat various inflammation-associated diseases, such as asthma, arthritis and pain. However, the anti-inflammatory active components of this plant have not been identified yet. The aim of this study was to investigate the potential analgesic and anti-inflammatory activities of a compound, quercetin-3-methoxy-4′-glucosyl-7-glucoside, isolated from M. heterophylla. Methods: The anti-inflammatory activity was determined using carrageenan- and dextran-induced rat paw edema as well as cotton pellet-induced granuloma in rats, whereas the analgesic activity was analyzed using acetic acid-induced writhing, hot plate and tail flick response in mice. The test compound was orally administered at a dose of 5, 10 or 15 mg/kg. The cyclooxygenase-1 (COX-1)- and COX-2-inhibitory capacity of the test compound was studied by enzyme immunosorbent assay. Results: Quercetin-3-methoxy-4′-glucosyl-7-glucoglucoside at 15 mg/kg exhibited a maximum inhibition of carrageenan-induced inflammation (50.3%, p < 0.05), dextran (52.8%, p < 0.05), and cotton pellets (41.4%, p < 0.05) compared to control animals. At the same dose, it showed a 73.1% inhibition (p < 0.05) of the pain threshold in acetic acid-induced writhing model. It also exhibited a considerable analgesic activity by prolonging the reaction time of the animals based on hot plate as well as tail flick response. The test compound was found to inhibit COX-1 (IC50 2.76 µg/mL) and more efficiently, COX-2 (IC50 1.99 µg/mL). Conclusions: Quercetin-3-methoxy-4′-glucosyl-7-glucoside possessed substantial analgesic and anti-inflammatory activities possibly due to inhibition of prostaglandin production, supporting the ethnomedicinal application of M. heterophylla to treat various inflammatory disorders
Use of āeā and āgā operators to a fuzzy production inventory control model for substitute items
In this paper, a fuzzy optimal control model for substitute items with stock and selling price dependent demand has been developed. Here the state variables (stocks) are assumed to be fuzzy variables. So the proposed dynamic control system can be represented as a fuzzy differential system which optimize the profit of the production inventory control model through Pontryaginās maximum principle. The proposed fuzzy control problem has been transformed into an equivalent crisp differential system using āeā and āgā operators. The deterministic system is then solved by using Newtonās forward-backward method through MATLAB. Finally some numerical results are presented both in tabular and graphical form
Designing Glass Nanocomposites with Nonbridging Oxygen Defects: An Approach to Improve Sodium-Ion Conduction
Samarium-doped glass nanocomposites were synthesized
following
the solāgel process employing mesoporous alumina as a template.
A series of nanocomposites comprising a nanoglass composition were
designed by tuning the ratio of Sm/Si. Modern characterization methods
were employed to conduct extensive microstructural investigations.
Comprehensive XPS studies were used to probe the underlying mechanism
of nonbridging oxygen defects in promoting Na-ion dynamics. Optical
absorption and FTIR investigations were employed to understand the
structural disorder with its influence on ion migration and reduction
of the activation energy. Using temperature-dependent impedance spectroscopy,
the impact of the structural morphology on the alkali-ion mobility
was investigated. The higher room-temperature ionic conductivity (ā¼5.2
Ć 10ā5 S cmā1) and lower
activation energy (0.08 eV) are mostly attributed to the nonbridging
oxygen defect. When operated over 250 cycles, galvanostatic chargeādischarge
cycles showed a retentive capacity of around 82.4% and a maximum specific
capacitance value of approximately 86.2 mAh/g. Our findings on structural
engineering of nanosilicate glass through rare-earth additives open
the possibility to engineer porous glass-based electrodes for sodium
battery application
A Novel Tetraenoic Fatty Acid Isolated from Amaranthus spinosus Inhibits Proliferation and Induces Apoptosis of Human Liver Cancer Cells
Amaranthus spinosus Linn. (Family: Amaranthaceae) has been shown to be useful in preventing and mitigating adverse pathophysiological conditions and complex diseases. However, only limited information is available on the anticancer potential of this plant. In this study, we examined the antiproliferative and pro-apoptotic effects of a novel fatty acid isolated from A. spinosusā(14E,18E,22E,26E)-methyl nonacosa-14,18,22,26 tetraenoateāagainst HepG2 human liver cancer cells. We used 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay to determine cell viability, flow cytometry assay for cell cycle analysis, and Western blot analysis to measure protein expression of Cdc2), cyclin B1, Bcl-2-associated X protein (Bax), and B-cell lymphoma 2 (Bcl-2). The MTT assay showed that the fatty acid markedly inhibited the proliferation of HepG2 cells in a dosage-dependent fashion, with a half maximal inhibitory concentration (IC50) value of 25.52 Āµmol/L. This antiproliferative result was superior to that of another known fatty acid, linoleic acid (IC50 38.65 Āµmol/L), but comparable to that of standard anticancer drug doxorubicin (IC50 24.68 Āµmol/L). The novel fatty acid also induced apoptosis mediated by downregulation of cyclin B1, upregulation of Bax, and downregulation of Bcl-2, resulting in the G2/M transition arrest. Our results provide the first experimental evidence that a novel fatty acid isolated from A. spinosus exhibits significant antiproliferative activity mediated through the induction of apoptosis in HepG2 cells. These encouraging results may facilitate the development of A. spinosus fatty acid for the prevention and intervention of hepatocellular carcinoma
SilverāNickel Bimetallic Nanowire-Based Transparent Thin-Film Spin-Glass Systems for Magnetic Sensor Applications
Silverānickel bimetallic nanowire-containing transparent
thin films (TFs) were investigated for their electrical and magnetic
properties. A facile solāgel technique followed by an electrodeposition
process was used to fabricate these samples. X-ray diffraction and
X-ray photoelectron spectroscopy were utilized to characterize the
constituent elements and to explain their electrical and magnetic
properties. Scanning electron microscopy and transmission electron
microscopy provided the details of microstructural features. Zero
field cooled (ZFC) and field cooled (FC) studies indicated the existence
of spin glass (SG), which was thoroughly investigated following FC
and ZFC memory effects along with relaxation dynamic studies. Scaling
law and VogelāFulcher law substantiated the presence of the
SG phase. Magnetodielectric results were explained using Catalanās
model assuming positive magnetoresistance. The magnetic field-dependent
charge transport mechanism explained the magnetoelectric coupling
and spin transport properties as a function of electric and magnetic
fields. A realistic circuit model with contributions from each component
as a function of the magnetic field was also discussed considering
the Nyquist plot. This study offers useful insights on bimetallic
nanowire-based TFs leading to the possible fabrication of magnetic
sensor devices