scholarly journals Influence of surface morphology on methanol oxidation at a glassy carbon-supported pt catalyst

2008 ◽  
Vol 73 (8-9) ◽  
pp. 845-859 ◽  
Author(s):  
S. Stevanovic ◽  
D. Tripkovic ◽  
A. Kowal ◽  
D. Minic ◽  
V.M. Jovanovic ◽  
...  
Keyword(s):  
Particle Size ◽  
Surface Morphology ◽  
Methanol Oxidation ◽  
Glassy Carbon ◽  
Active Sites ◽  
Spherical Particles ◽  
Pt Catalyst ◽  
Alkaline Solutions ◽  
Real Surface ◽  
Step Method

Platinum supported on glassy carbon (GC) was used as a model system for studying the influence of the surface morphology of a Pt catalyst on methanol oxidation in alkaline and acidic solutions. Platinum was deposited by the potential step method on GC samples from H2SO4 + H2PtCl6 solution under the same conditions with loadings from 10 to 80 mg cm-2. AFM and STM images of the GC/Pt electrodes showed that the Pt was deposited in the form of 3D agglomerates composed of spherical particles. Longer deposition times resulted in increased growth of Pt forms and a decrease in the specific area of the Pt. The real surface area of Pt increased with loading but the changes were almost negligible at higher loadings. Nevertheless, both the specific and mass activity of platinum supported on glassy carbon for methanol oxidation in acidic and in alkaline solutions exhibit a volcanic dependence with respect to the platinum loading. The increase in the activity can be explained by the increasing the particle size with the loading and thus an increase in the contiguous Pt sites available for adsorption and decomposition of methanol. However, the decrease in the activity of the catalyst with further increase of loading and particle size after reaching the maximum is related to the decrease of active sites available for methanol adsorption and their accessibility as a result of more close proximity and pronounced coalescence of the Pt particles.

Design, Optimization and in vitro Characterization of Dasatinib loaded PLGA Nano carrier for Targeted cancer therapy: A Preliminary Evaluation

2021 ◽  
pp. 2095-2100
Author(s):  
Shyam S Kumar ◽  
G. Gopalakrishnan ◽  
N. L. Gowrishankar
Keyword(s):  
Particle Size ◽  
Drug Release ◽  
Zeta Potential ◽  
Surface Morphology ◽  
Dissolution Rate ◽  
Water Soluble ◽  
Spherical Particles ◽  
Preliminary Evaluation ◽  
Pluronic F68

Objective: Drug nanoparticles offer a versatile platform for enhancing the dissolution rate and bioavailability of poorly water soluble drugs The present study was aimed to design and develop dasatinib (DAS) loaded Poly lactide co glycolic acid (PLGA) to enhance the dissolution rate and to study the effect of formulation variables for the BCS class II drug dasatinib for the treatment of chronic myeloid leukemia. Methods: The DAS loaded Nps were prepared by using modified double emulsion solvent evaporation method (DESE) using different stabilizers, the formulated Nps were characterized for particle size, zeta potential, Poly Dispersity Index, Surface morphology, Drug entrapment and Invitro drug release. Results: The DAS loaded NP s showed the lowest particles size of 123 nm and zeta potential of – results of Pluronic F68 loaded NP showed the lowest particle size of – and highest zeta potential of --. Surface morphology of NPs with DMAB showed distinct smooth spherical particles with the size range of 50nm. Morphology of Pluronic F68 formulated NPs showed the high degree of aggregation. In vitro drug release showed up to 24hrs in a sustained manner. Conclusion: The result of our study indicates the use of PLGA as a sustained release polymer and using DMAB as a stabilizer for better stable formulation.

The effect of electrochemically treated glassy carbon on the activity of supported Pt catalyst in methanol oxidation

2004 ◽  
Vol 6 (12) ◽  
pp. 1254-1258 ◽  
Author(s):  
V.M. Jovanović ◽  
S. Terzić ◽  
A.V. Tripković ◽  
K.Dj. Popović ◽  
J.D. Lović
Keyword(s):  
Methanol Oxidation ◽  
Glassy Carbon ◽  
Pt Catalyst ◽  
Supported Pt Catalyst

Study of 5-Fluorouracil Loaded Chitosan Nanoparticles for Treatment of Skin Cancer

2020 ◽  
Vol 14 (3) ◽  
pp. 210-224
Author(s):  
Gayatri Patel ◽  
Bindu K.N. Yadav
Keyword(s):  
Particle Size ◽  
Controlled Release ◽  
Skin Cancer ◽  
Basal Cell Carcinoma ◽  
Cell Carcinoma ◽  
Basal Cell ◽  
Chitosan Nanoparticles ◽  
Entrapment Efficiency ◽  
Fractional Factorial ◽  
Spherical Particles

Background: The purpose of this study was to formulate, characterize and in-vitro cytotoxicity of 5-Fluorouracil loaded controlled release nanoparticles for the treatment of skin cancer. The patents on nanoparticles (US8414926B1), (US61654404A), (WO2007150075A3) etc. helped in the selection polymers and method for the preparation of nanoparticles. Methods: In the present study nanoparticles were prepared by simple ionic gelation method using various concentrations of chitosan and sodium tripolyphosphate (TPP). Several process and formulation parameters were screened and optimized using 25-2 fractional factorial design. The prepared nanoparticles were evaluated for particle size, shape, charge, entrapment efficiency, crosslinking mechanism and drug release study. Results: The optimized 5-Fluorouracil loaded nanoparticle were found with particle size of of 320±2.1 nm, entrapment efficiency of 85.12%± 1.1% and Zeta potential of 29mv±1mv. Scanning electron microscopy and dynamic light scattering technique revealed spherical particles with uniform size. The invitro release profile showed controlled release up to 24 hr. Further study was carried using A375 basal cell carcinoma cell-line to elucidate the mechanism of its cytotoxicity by MTT assay. Conclusion: These results demonstrate that the possibility of delivering 5-Fluorouracil to skin with enhanced encapsulation efficiency indicating effectiveness of the formulation for treatment of basal cell carcinoma type of skin cancer.

Isolasi Dan Karakterisasi Bentonit Alam Menjadi Nanopartikel Monmorillonit

2018 ◽  
Vol 3 (1) ◽  
pp. 12 ◽  
Author(s):  
Zaimahwati Zaimahwati ◽  
Yuniati Yuniati ◽  
Ramzi Jalal ◽  
Syahman Zhafiri ◽  
Yuli Yetri
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Particle Size ◽  
Surface Morphology ◽  
Average Diameter ◽  
Particle Size Analyzer ◽  
Ft Ir ◽  
Scanning Electron ◽  
Sedimentation Processes

<p>Pada penelitian ini telah dilakukan isolasi dan karakterisasi bentonit alam menjadi nanopartikel montmorillonit. Bentonit alam yang digunakan diambil dari desa Blangdalam, Kecamatan Nisam Kabupaten Aceh Utara.  Proses isolasi meliputi proses pelarutan dengan aquades, ultrasonic dan proses sedimentasi. Untuk mengetahui karakterisasi montmorillonit dilakukan uji FT-IR, X-RD dan uji morfologi permukaan dengan Scanning Electron Microscopy (SEM). Partikel size analyzer untuk menganalisis dan menentukan ukuran nanopartikel dari isolasi bentonit alam. Dari hasil penelitian didapat ukuran nanopartikel montmorillonit hasil isolasi dari bentonit alam diperoleh berdiameter rata-rata 82,15 nm.</p><p><em>In this research we have isolated and characterized natural bentonite into montmorillonite nanoparticles. Natural bentonite used was taken from Blangdalam village, Nisam sub-district, North Aceh district. The isolation process includes dissolving process with aquades, ultrasonic and sedimentation processes.  The characterization of montmorillonite, FT-IR, X-RD and surface morphology test by Scanning Electron Microscopy (SEM). Particle size analyzer to analyze and determine the size of nanoparticles from natural bentonite insulation. From the research results obtained the size of montmorillonite nanoparticles isolated from natural bentonite obtained an average diameter of 82.15 nm.</em></p>

scholarly journals Spinel of Nickel-Cobalt Oxide with Rod-Like Architecture as Electrocatalyst for Oxygen Evolution Reaction

Materials ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 3918
Author(s):  
Anna Dymerska ◽  
Wojciech Kukułka ◽  
Marcin Biegun ◽  
Ewa Mijowska
Keyword(s):  
Cobalt Oxide ◽  
Oxygen Evolution ◽  
Active Sites ◽  
Solvothermal Reaction ◽  
Step Method ◽  
One Pot ◽  
Widespread Application ◽  
Nickel Cobalt ◽  
Slow Kinetics ◽  
Nickel Cobalt Oxide

The renewable energy technologies require electrocatalysts for reactions, such as the oxygen and/or hydrogen evolution reaction (OER/HER). They are complex electrochemical reactions that take place through the direct transfer of electrons. However, mostly they have high over-potentials and slow kinetics, that is why they require electrocatalysts to lower the over-potential of the reactions and enhance the reaction rate. The commercially used catalysts (e.g., ruthenium nanoparticles—Ru, iridium nanoparticles—Ir, and their oxides: RuO2, IrO2, platinum—Pt) contain metals that have poor stability, and are not economically worthwhile for widespread application. Here, we propose the spinel structure of nickel-cobalt oxide (NiCo2O4) fabricated to serve as electrocatalyst for OER. These structures were obtained by a facile two-step method: (1) One-pot solvothermal reaction and subsequently (2) pyrolysis or carbonization, respectively. This material exhibits novel rod-like morphology formed by tiny spheres. The presence of transition metal particles such as Co and Ni due to their conductivity and electron configurations provides a great number of active sites, which brings superior electrochemical performance in oxygen evolution and good stability in long-term tests. Therefore, it is believed that we propose interesting low-cost material that can act as a super stable catalyst in OER.

scholarly journals Non-Isothermal Decomposition as Efficient and Simple Synthesis Method of NiO/C Nanoparticles for Asymmetric Supercapacitors

Nanomaterials ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 187
Author(s):  
Daria Chernysheva ◽  
Ludmila Pudova ◽  
Yuri Popov ◽  
Nina Smirnova ◽  
Olga Maslova ◽  
...  
Keyword(s):  
Nickel Oxide ◽  
Synthesis Method ◽  
Average Diameter ◽  
Carbon Support ◽  
Spherical Particles ◽  
Support Surface ◽  
Isothermal Decomposition ◽  
Step Method ◽  
Nickel Oxide Nanoparticles ◽  
Electrode Cell

A series of NiO/C nanocomposites with NiO concentrations ranging from 10 to 90 wt% was synthesized using a simple and efficient two-step method based on non-isothermal decomposition of Nickel(II) bis(acetylacetonate). X-ray diffraction (XRD) measurements of these NiO/C nanocomposites demonstrate the presence of β-NiO. NiO/C nanocomposites are composed of spherical particles distributed over the carbon support surface. The average diameter of nickel oxide spheres increases with the NiO content and are estimated as 36, 50 and 205 nm for nanocomposites with 10, 50 and 80 wt% NiO concentrations, respectively. In turn, each NiO sphere contains several nickel oxide nanoparticles, whose average sizes are 7–8 nm. According to the tests performed using a three-electrode cell, specific capacitance (SC) of NiO/C nanocomposites increases from 200 to 400 F/g as the NiO content achieves a maximum of 60 wt% concentration, after which the SC decreases. The study of the NiO/C composite showing the highest SC in three- and two-electrode cells reveals that its SC remains almost unchanged while increasing the current density, and the sample demonstrates excellent cycling stability properties. Finally, NiO/C (60% NiO) composites are shown to be promising materials for charging quartz clocks with a power rating of 1.5 V (30 min).

A Parametric Numerical Study of Radiative Transfer in Thermotropic Materials

2013 ◽  
Author(s):  
Adam C. Gladen ◽  
Susan C. Mantell ◽  
Jane H. Davidson
Keyword(s):  
Particle Size ◽  
Radiative Transfer ◽  
Optical Thickness ◽  
Parametric Study ◽  
Volume Fraction ◽  
Numerical Study ◽  
Anisotropic Scattering ◽  
Index Of Refraction ◽  
Spherical Particles ◽  
Size Parameter

A thermotropic material is modeled as an absorbing, thin slab containing anisotropic scattering, monodisperse, spherical particles. Monte Carlo ray tracing is used to solve the governing equation of radiative transfer. Predicted results are validated by comparison to the measured normal-hemispherical reflectance and transmittance of samples with various volume fraction and relative index of refraction. A parametric study elucidates the effects of particle size parameter, scattering albedo, and optical thickness on the normal-hemispherical transmittance, reflectance, and absorptance. The results are interpreted for a thermotropic material used for overheat protection of a polymer solar absorber. For the preferred particle size parameter of 2, the optical thickness should be less than 0.3 to ensure high transmittance in the clear state. To significantly reduce the transmittance and increase the reflectance in the translucent state, the optical thickness should be greater than 2.5 and the scattering albedo should be greater than 0.995. For optical thickness greater than 5, the reflectance is asymptotic and any further reduction in transmittance is through increased absorptance. A case study is used to illustrate how the parametric study can be used to guide the design of thermotropic materials. Low molecular weighted polyethylene in poly(methyl methacrylate) is identified as a potential thermotropic material. For this material and a particle radius of 200 nm, it is determined that the volume fraction and thickness should equal 10% and 1 mm, respectively.

Microbial-Induced Mineralization of Zinc Ions Based on the Degradation of Toluene and Its Characterization

2021 ◽  
Vol 13 (4) ◽  
pp. 656-661
Author(s):  
Yiyan Lv ◽  
Qiwei Zhan ◽  
Xiaoniu Yu
Keyword(s):  
Particle Size ◽  
Phase Composition ◽  
Surface Morphology ◽  
Organic Compounds ◽  
Low Cost ◽  
Zinc Ion ◽  
Zinc Ions ◽  
Quick Response ◽  
Zinc Carbonate ◽  
Carbonate Ions

Microbial-induced degradation of aromatic organic compounds and mineralization of zinc ions have attracted much attention because of its low cost, simple operation and quick response. This research, toluene was decomposed and made the concentration of carbonate ions increased accordingly by the enzymatic pressing of microorganisms, meanwhile carbonate ions mineralized zinc ions into carbonate precipitations. The composition and microstructure were analyzed systematically. The analysis results indicated that carbonate precipitations, basic zinc carbonate, could be successfully prepared by microbial method. The particle size of basic zinc carbonate was nanometer, and its shape was near-spherical. Furthermore, the phase composition, functional groups and surface morphology of the precipitations prepared by different methods were basically the same. This work provided a new method for remediation of zinc ion pollution based on the degradation of toluene.

scholarly journals EVALUATION OF STABILITY OF ROPINIROLE HYDROCHLORIDE AND PRAMIPEXOLE DIHYDROCHLORIDE MICROSPHERES AT ACCELERATED CONDITION

2018 ◽  
Vol 10 (4) ◽  
pp. 82
Author(s):  
Koyel Kar ◽  
R. N. Pal ◽  
Gouranga Nandi
Keyword(s):  
Particle Size ◽  
Drug Release ◽  
Surface Morphology ◽  
Shelf Life ◽  
Stability Study ◽  
In Vitro Drug Release ◽  
Drug Content ◽  
Ropinirole Hydrochloride ◽  
Pramipexole Dihydrochloride

Objective: The objective of the present work was to conduct accelerated stability study as per international council for harmonisation (ICH) guidelines and to establish shelf life of controlled release dosage form of ropinirole hydrochloride and pramipexole dihydrochloride microspheres for a period of 6 mo.Methods: Most optimized batch of ropinirole hydrochloride and pramipexole dihydrochloride (F12 and M12 respectively) were selected and subjected to exhaustive stability testing by keeping the sample in stability oven for a period of 3 and 6 mo. Various parameters like surface morphology, particle size, drug content, in vitro drug release and shelf life were evaluated at 3 and 6 mo period. The surface morphology of the formulated microspheres was determined by scanning electron microscopy (SEM). The particle size of the microspheres was estimated by optical microscopy method. The drug content was assayed by the help of ultra-violet spectrophotometer (UV). The in vitro drug release was performed by using Paddle II type dissolution apparatus and the filtrate was analyzed by UV spectrophotometer. The shelf life of the optimized microspheres was calculated by using the rate constant value of the zero-order reaction.Results: A minor change was recorded in average particle size of F12 and M12 microspheres after storage for 6 mo. For F12 and M12, initially the particle size was 130.00 µm and 128.92 µm respectively and after 6 mo it was found to be 130.92 µm and 128.99 µm respectively. There was no change in surface morphology of F12 and M12 microspheres after 6 mo of storage. The shape of microspheres remained spherical and smooth after 6 mo. An insignificant difference of drug content was recorded after 6 mo compared to the freshly prepared formulation. For F12 and M12, 94.50% and 93.77% of the drug was present initially and after 6 mo 94.45% and 93.72% of the drug was recorded. In vitro drug release was recorded after 6 mo for F12 and M12. Initially, 97.99% and 97.69% of the drug was released till 14th hour respectively for F12 and M12. After 6 mo, 98.23% and 97.99% of the drug was released respectively. The percentage residual drug content revealed that the degradation of microspheres was low. Considering the initial percentage residual drug content as 100%, 99.94% of the drug was recorded for both F12 and M12. The shelf life for F12 and M12 was found to be 10 y 52 d and 10 y 70 d respectively which were determined by the zero-order kinetic equation.Conclusion: A more or less similar surface morphology, particle size, drug content and percent of drug release before and after stability study confirmed the stability of F12 and M12 microspheres after storage for 6 mo and prove the efficacy of the microspheres in the site-specific delivery of drugs in Parkinson’s disease.

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