Search results for "engineering.material"

Copper(I)‐chitin biopolymer based: An efficient and recyclable catalyst for click azide–alkyne cycloaddition reactions in water

2021

Polymer support synthesis

1989

Non-porous silica gel microbeads of diameter 1.5 microns have been investigated as supports for oligonucleotide synthesis. In the preparation of oligothymidylates of chain length up to 150 bases, with 5'-di-p-anisylphenylmethyl-3'-phosphoramidite as an intermediate, the average yields per chain elongation were up to 99%. Lower overall yields were observed in the case of a support which developed a strong tendency towards aggregation after the build up of an oligonucleotide coating.

Effect of polystyrene coating on pore, structural and chromatographic properties of silica packings

1990

Abstract A series of mesoporous and macroporous silicas with a mean pore diameter (PD), between 6 and 200 nm were reacted with a copolymer of styrene and vinyl-methyldiethoxysilane. The mass load of coated silicas corresponded to the monolayer capacity of the polymer calculated on the basis of the molecular cross-sectional area, except for the two mesoporous silcias of PD = 6 and 7.5 nm. Depending on the pore size, changes occurred in the specific surface area, as, between the native and the coated product. A comparison of the specific pore volume, νp, of silicas before and after polymer immobilization indicated a major loss of νp for the two mesoporous silicas whereas this effect was much …

Optimisation of fast protein separations on non-porous silica-based strong anion exchangers

1993

The adsorbed coating technology using various vinylpyrrolidone-vinylimidazole copolymer compositions was carried out on 1.7 μm non-porous monodisperse silica. It was shown that the retention properties and the loading capacity for bovine serum albumin (BSA) increases with the amount of vinylimidazole in the copolymer composition. The retention behavior of various proteins as a function of the salt composition in the eluent has been applied to find the optimal conditions for the synthesis of the anion-exchange stationary phase. The suitability of these supports for the fast separation of biological molecules is demonstrated. The best resolution and the highest speed in protein analysis was o…

Effects of compost input and tillage intensity on soil microbial biomass and activity under Mediterranean conditions

2010

Organic amendment and tillage reduction are two common practices to contrast soil organic matter decline, thus promoting sustainable cropping and carbon sequestration. In a horticultural land use system under Mediterranean climate, we evaluated the 9-year effects of two compost inputs (15 and 30 t ha−1 y−1, low and high input, respectively) and two tillage intensities (intensive and reduced) on soil macronutrients concentration, microbial biomass and activity. Total organic C, total N and POlsen were smaller in plots amended at low input, whilst intensive tillage decreased them at both compost inputs. These decreases in intensively tilled plots was ascribed to the disruption of soil aggrega…

Persistent photovoltage in methylammonium lead iodide perovskite solar cells

2014

Open circuit voltage decay measurements are performed on methylammonium lead iodide (CH3NH3PbI3) perovskite solar cells to investigate the charge carrier recombination dynamics. The measurements are compared to the two reference polymer-fullerene bulk heterojunction solar cells based on P3HT:PC60BM and PTB7:PC70BM blends. In the perovskite devices, two very different time domains of the voltage decay are found, with a first drop on a short time scale that is similar to the organic solar cells. However, two major differences are also observed. 65-70% of the maximum photovoltage persists on much longer timescales, and the recombination dynamics are dependent on the illumination intensity.

Electrochromic Performances of Poly(Azure A) Films from Digital Video-Electrochemistry (DVEC)

2020

Poly(Azure A) (PAA) films doped with sodium dodecyl sulfate (SDS) were grown on transparent indium tin oxide (ITO) glass substrates by cyclic voltammetry. The electrochromism of PAA was investigated by digital video-electrochemistry (DVEC). DVEC consists of the acquisition of sequential digital images during the electro-stimulated changes of PAA color. The evolution of red, green, and blue (R, G, B) colors intensity (I) of analyzed pixels provides enough sensitivity to detect changes of some nmol cm−2 of electroactive centers. Besides, the different time evolution of these color intensities can serve to discern among different electroactive centers activated in the polymer. For the first ti…

Effect of storage and composting on the properties and degradability of cattle manure

1995

Abstract Stockpiling or thermophilic composting of cattle manure resulted in significant carbon losses of 17% and 26.4% and relative nitrogen gains of 25% and 32.7% for stockpiled and composted manure, respectively. As a consequence, C/N ratios decreased with increasing time of storage or composting. However, neither the pH nor the mineral nitrogen and organic carbon contents of the 0–50 μm fractions were significant indicators of the transformations of these materials. The degradability of the manure was measured by incubation for 2 weeks in a brown calcareous soil, following 1 week of preincubation. The biodegradation index (BI) or the proportion of CO 2 released from the amended soil in …

The abundance of Au, Pt, Pd, and the mode of heavy metal fixation in highly polluted sediments from the Rhine River near Mainz, West Germany

1984

The Au, Pt and Pd contents of the sediments of Ginsheimer‐Altrhine River, a channel of the Rhine river which drains one of the most industrialized regions of western Europe, have been determined by flameless atomic absorption spectrophotometry. The abundances of these noble metals range from 96–460 ppb Au; 734 ppb‐31 ppm Pt and 32 ppb‐4 ppm Pd. The extremely high concentrations, particulary those of Pt and Pd, are attributed to their use in industry and are due to the formation and concentration of metal‐organic complexes, mainly at the interface between an extremely reducing and an oxidizing aquatic environment. Differential thermal analyses of the polluted sediments in comparison to the p…

Quantitative study of the capture of silver nanoparticles by several kinds of soils

2018

The capacity of different soils to capture silver nanoparticles (AgNPs) by measuring changes of an AgNP intrinsic property such as the plasmon for the first time, was studied. In-tube solid-phase microextraction (IT-SPME) coupled on-line to capillary liquid chromatography (CapLC) with diode array detection (DAD) was employed for measuring the interactions between soil and in-contact AgNP dispersions. Its achieved LOD 9 pM assures quantitative retention measurements and selectivity for soil lixiviation was suitable. Electronic microscopy was employed for corroborating the entrapped Ag into the soils. Capture % of AgNPs was calculated in compost (>99%), mountain (>99%), orchard (15±1%) and ur…