Tunable morphological properties of silver enriched platinum allied nanoparticles and their catalysed reduction of p-nitrophenol

A robust polymer based and polyol mediated procedure to synthesize nanobimetallic particles has been modified to produce core–shell and alloy Ag/Pt nanoparticles with tunable properties. Novel three-dimensional (3D) quasi nanocubes entangled in nanowebs were produced by rapid solution phase transformation with hot addition of absolute ethanol. The optical characterization showed extinction of plasmon resonance band occurring with incremental feeding ratio of Pt source in all cases. Transmission electron microscope (TEM) and high resolution transmission electron microscope (HRTEM) images revealed that the shape, size and size distribution of asprepared silver platinum nanoparticles depended on the stabilizer or capping agent, mole ratio of metal ion sources, temperature and time of reaction. Meanwhile, catalytic activity was highest in the reduction of p-nitrophenol in the presence of polyvinylpyrrolidone/diethylene glycol stabilized Ag/Pt nanoparticles

Polymerization of propene with tBuNSiMe2C5Me4TiMe2: Effects of trialkylaluminiums as additives

Propene was polymerized at 0 oC with tBuNSiMe2C5Me4TiMe2/MAO. Kinetic features and other parameters indicated quasi-living polymerization. Effects of various trialkylaluminiums as additives have been investigated; it was found that compounds with more bulky groups like iBu3Al, Oct3Al increased the activities significantly whereas Me3Al and Et3Al reduced the activities of the catalyst system. The triad sequence in the 13C NMR spectrum confirmed a syndiotactic-enriched atactic polypropene. KEY WORDS: Polymerization of propene, tBuNSiMe2C5Me4TiMe2, Trialkylaluminiums, Syndiotactic-enriched atactic polypropene  Bull. Chem. Soc. Ethiop. 2004, 18(2), 131-141

Development Of Oil In Water Nanoemulsion Formulations For Spontaneous Transdermal Delivery Of Drugs

Nanoemulsions have attracted attention in delivery of therapeutically active agents since most of the new chemical entities are hydrophobic in nature and the delivery of poor water soluble drugs is a challenge. This study was carried out to adopt nanoemulsion as a means of entrapping Ciprofloxacin in the oil phase of the emulsion for transdermal drug delivery. Nanoemulsions were formulated as oil in water (O/W) type and prepared by self-mild mechanical nanoemulsification method. The formulation consisted of Sandbox (Hura crepitan) and Sesame seed (Sesamum indicum) as the organic phase of the emulsion, Polyethylene (20) sorbitanmonooleate (Tween 80) and Polyethylene (20) sorbitan monolaurate (Tween 20) as the surfactants and Polyehtylene glycol (PEG 400) as co-surfactant. The formulations were tested and characterized. Ciprofloxacin (0.075 g) was incorporated into the oil phase of the most stable nanoemulsion formulation prior emulsification and tested on Escherichia Coli. Transdermal application was done on white albino rats (R). The result showed the zones of inhibition of HCa3+Ciprofloxacin and SSA3+Ciprofloxacinn to be 26.00 and 25.00 mm respectively. The HPLC results showed, out of 75000 μg of Ciprofloxacin loaded in the oil phases of HCa3 and SSA3 formulations, 6.0076 (R2), 0.4112 (R3) and 6.7241 μg (R6) were absorbed in HCa3 while 1.9519 (R1), 1.2631 (R4) and 2.1801 μg (R5) were absorbed in SSA3. The SEM images revealed an encapsulation with globule size diameter of 94 and 63 nm respectively. The findings of this work showed that sandbox and Sesame seed oil based nanoemulsion is effective for transdermal drug delivery

Green Synthesis of Pseudo-Cubic Ag/Ni Bimetallic Nanoparticles using Senna occidentalis Leaf Extract

Abstract.This study reports plant-mediated co-reduction approach for the synthesis of Ag/Ni bimetallic nanoparticles (Ag/Ni BNPs). In view of sustainability development, aqueous leaf extract of an indigenous Senna occidentalis (coffee senna) acted as a reducing agent. Cold extraction was carried out on the biodiversity plant using water and methanol as solvent media by way of “green” synthesis. Qualitative analysis was done to identify possible secondary metabolites present in the extract. Synthesis of the nanohybrid was achieved using two different precursor concentrations at 70°C. Techniques including Uv-visible spectroscopy, scanning electron microscopy and energy dispersive X-ray spectroscopy were engaged for optical, morphological and compositional characterisation of the Ag/Ni BNPs, respectively. The reaction colour changed from green to dark brown due to the excitation of electron and change in the electronic energy levels of metal nanoparticles. Presence of nickel in the nanohybrid resulted in blue shift in the absorbance wavelengths when compared with the corresponding monometallic Ag NPs (341 to 327 nm). The optical property displayed by Ag/Ni BNPs is a pointer for potential application as optical materia

Green Synthesized Optically Active Organically Capped Silver Nanoparticles using Stem Extract of African Cucumber(Momordica charantia)

Silver nanoparticles (Ag NPs) were synthesized by a rapid facile plant-mediated green route. Sustainable and renewable stem extract of locally sourced African cucumber acted as reducing/capping agent, an alternative to toxic chemicals. The phytochemical screening indicated the existence of saponins and alkaloids in the stem extract of M. charantia. Unprecedented nucleation and growth of Ag NPs commenced within 5 minutes of the reaction. The mechanism of reaction was considered to be diffusion controlled Ostwald ripening process. Optical property of the as prepared Ag NPs was characterized by high intensity of absorption, revealed by narrow intense peaks, stipulating confinement of excitons.Surface Plasmon Band (SPB) of Ag NPs appeared at 400 - 460 nm. Photoluminescence (PL)excitation of the Ag NPs at 329 nm exhibited excitonic emission at 440 nm. The Ag NPs portrayed quasi-spherical shapes, with a mean size of 27.81 ± 1.64 nm from Transmission Electron Micrograph (TEM) measurement. XRD measurement showed peaks indexed to fcc Ag with a particle diameter of 25 nm, which corroborated TEM measurement. Elemental mapping of the nanoparticles showed an orientation of the Ag NPs, an evidence of capping by the biomolecules which stabilized the newly formed Ag NPs. Fourier Transformed Infra-red (FTIR) analysis showed the presence of hydroxyl groups (−OH) stretching, (−CH) stretching,C=C stretching and C−N group (in the phytochemicals) at 3237, 2913, 1620 and 1021 cm-1 respectively. It can be inferred that the as prepared Ag NPs is an optically active material

Synthesis of polyol based Ag/Pd nanocomposites for applications in catalysis

The synthesis of polyvinylpyrrolidone seed mediated Ag/Pd allied nanobimetallic particles was successfully carried out by the simultaneous reduction of the metal ions in ethylene glycol, diethylene glycol, glycerol, pentaerythritol and sodium borohydride solution. The optical measurement revealed the existence of peak broadening that causes diffusion processes of the metal sols to decrease making it possible to monitor the changes spectrophotometrically. This, together with X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM) and high resolution TEM measurements strongly support the conclusion that intimately alloyed clusters were formed and the particle growth anisotropy is diffusion limited. Finally, the catalytic potential of the nanocomposites was investigated using 4-nitrophenol in the presence of sodium borohydride at 299 K; a good linear fitting of ln (A/A0) versus the reaction time was obtained, indicating pseudo-first-order kinetic

Green Synthesis, Characterization of Silver Nanoparticles Using Canna indica and Senna occidental is Leaf Extracts

Green synthesis is now considered an alternative to chemical and physical synthetic procedures for nanoparticles by using sustainable and eco-friendly materials instead of harsh and toxic chemicals. This research aimed at synthesizing silver nanoparticles using locally- sourced leaf extracts of Canna indica and Senna occidentalis. The syntheses were monitored with double beam UV-Visible spectrophotometer. Aliquot samples were taken at time intervals (5, 10, 15, 20, 30 minutes) during bioreduction. Colour changes were observed in the process of Ostwald ripening in both syntheses. Again, excitation of surface plasmon resonance was obvious in the nanosilver formed by the biomass. Red shifting indicating particle size increase ( 400-430 nm), and blue shifting (350-380 nm) were evident in Canna indica and Senna occidentalis silver nanoparticles respectively. Energy dispersed analysis by Xray (EDAX) indicated silver oxide peaks, and scanning electron microscopy (SEM) showed an amorphous phase of the nanoparticles as further proofs of nanosilver formation from both extracts

Biosynthesis of silver nanoparticles using Garcinia kola and its antimicrobial potential

We have investigated the green synthesis and antimicrobial activity of silver nanoparticles using Garcinia kola. Aqueous extract of G. kola was used to reduce AgNO3 solution to obtain black nanocrystal of silver nanoparticles. Antimicrobial activity of the silver nanoparticles was tested against Escherichia coli, Klebsiella pneumonia, Bacillus subtilis, Staphylococcus aureus, Aspergillus niger, Rhizopus stolonifer and Candida albican. The synthesized silver nanoparticles was characterized using UV-vis spectroscopy, X-ray diffraction (XRD), Transmission electron microscopy (TEM), and Fourier transform infrared (FTIR) spectroscopy. UV-visible exhibits prominently the characteristic surface plasmon resonance at around 427 nm. A remarkable particle growth onset of 10 min was observed while the reaction ended within 30 min. The XRD analysis shows that the synthesized silver nanoparticles are crystalline in nature and well-dispersed silver nanoparticles with an approximate size of 10.4 nm were observed on TEM. The synthesized silver was found to possess good antimicrobial activity against all the tested microbes. The application of the green synthesized nanoparticles can be used in many fields such as foods, beverages, cosmetics and medicine

Modeling and Synthesis of Ag and Ag/Ni Allied Bimetallic Nanoparticles by Green Method: Optical and Biological Properties

In the quest for environmental remediation which involves eco-friendly synthetic routes, we herein report synthesis and modeling of silver nanoparticles (Ag NPs) and silver/nickel allied bimetallic nanoparticles (Ag/Ni NPs) using plant-extract reductionmethod. Secondary metabolites in the leaf extract of Canna indica acted as reducing agent. Electronic transitions resulted in emergence of surface plasmon resonance in the regions of 416 nm (Ag NPs) and 421nm (Ag/Ni NPs) during optical measurements. Further characterizations were done using TEM and EDX. Antimicrobial activity of the nanoparticles against clinical isolates was highly significant a

Analysis of grain yield components of selected upland rice grown in valley bottom soil under rates of foliar ortho-silicate acid fertiliser

Attainment of potential yield (PY) of upland rice grown in valley bottom (VB) soil is limited by inadequate supply of beneficial nutrients. Previous study revealed that VB soil increase grain weight plant-1 (GWP) in upland rice by 70%, which is still far below its PY. Application of ortho-silicate acid (OSA) fertiliser, as silicon source at optimum rate, could help to boost the yield of upland rice. Five upland rice cultivars, comprising of three medium maturing (NERICA 1,4,7) and late maturing (MOROBEREKAN and OFADA), were grown in pots filled with VB soil. Four rates of foliarly applied OSA fertiliser (0, 250, 500, and 750 ml ha-1) were imposed across stages of growth of rice cultivars. OSA fertiliser increased GWP significantly (P<0.01) with application of 500 ml ha-1 having the best effect. At 250 ml ha-1, 1000 grain weights was more associated with number of branches panicle-1 and number of grains branch-1 panicle-1; while at 500 ml ha-1, GWP was closely associated with % number of fertile spikelets panicle-1 plant-1 (%NFSPP), total weight of panicle plant-1 (TWPP) and length of panicle plant-1 (LPP). Total number of spikelets plant-1 was more associated with total number of panicle plant-1 at 750 ml ha-1. The highest significant (P<0.01) GWP was observed in MOROBEREKAN (9.27 g plant-1); while the lowest was in Ofada (4.79 g plant-1). Application of 500 ml ha-1 of the fertiliser is recommended for these rice cultivars. Further improvement in yield of upland rice grown on VB soil under foliarly applied silicon should focus on % NFSPP, TWPP, and LPP.L\u2019atteinte d\u2019un rendement potentiel (RP) de riz pluvial cultiv\ue9 dans le sol de fond de vall\ue9e (FV) est limit\ue9e par un apport insuffisant de nutriments b\ue9n\ue9fiques. Une \ue9tude pr\ue9c\ue9dente a r\ue9v\ue9l\ue9 que le sol de fond de vall\ue9e (VB) augmente le poids de grain par plante (PGP) dans le riz pluvial de 70%, ce qui est encore bien en dessous de son rendement potentiel (RP). L\u2019application d\u2019engrais d\u2019acide orthosilicate (AOS), comme source de silicium \ue0 un taux optimal, pourrait aider \ue0 augmenter le rendement du riz pluvial. Cinq cultivars de riz pluvial, comprenant trois \ue0 maturation moyenne (NERICA 1,4,7) et \ue0 maturation tardive (MOROBEREKAN et OFADA), ont \ue9t\ue9 cultiv\ue9s dans des pots remplis de terre FV. Quatre taux d\u2019engrais AOS appliqu\ue9s par voie foliaire (0, 250, 500 et 750 ml ha-1) ont \ue9t\ue9 impos\ue9s \ue0 tous les stades de croissance des cultivars de riz. L\u2019engrais AOS a augment\ue9 PGP de mani\ue8re significative (P <0,01) avec l\u2019application de 500 ml ha-1 ayant le meilleur effet. \uc0 250 ml ha-1, 1000 poids de grain \ue9taient davantage associ\ue9s au nombre de branches par panicule et au nombre de grains par branche et par panicule; alors qu\u2019\ue0 500 ml ha-1, PGP \ue9tait \ue9troitement associ\ue9 au% nombre d\u2019\ue9pillets fertiles par panicule et par plante (% NEFPP), au poids total de la panicule par plante (PTPP) et \ue0 la longueur de la panicule par plante (LPP). PGP significatif le plus \ue9lev\ue9 (P <0,01) a \ue9t\ue9 observ\ue9 \ue0 MOROBEREKAN (9,27 g plante-1); tandis que le plus bas \ue9tait \ue0 Ofada (4,79 g de plante-1). L\u2019application de 500 ml ha-1 d\u2019engrais est recommand\ue9e pour ces cultivars de riz. Une am\ue9lioration suppl\ue9mentaire du rendement du riz pluvial cultiv\ue9 sur le sol FV sous silicium appliqu\ue9 par voie foliaire devrait se concentrer sur le% NEFPP, PTPP et LPP