NaOH Treatment (naoh + treatment)

Distribution by Scientific Domains


Selected Abstracts


Hierarchical Zeolite Catalysts: Zeolite Catalysts with Tunable Hierarchy Factor by Pore-Growth Moderators (Adv. Funct.

ADVANCED FUNCTIONAL MATERIALS, Issue 24 2009
Mater.
On page 3972, Pérez-Ramírez et al. introduce the hierarchy factor as a valuable descriptor to categorize hierarchical zeolites and to optimize their design for catalytic applications. They demonstrate a direct correlation between the catalytic performance of ZSM-5 in benzene alkylation and the hierarchy factor. Maximization of the hierarchy factor is achieved by enhancing the mesopore surface area without reducing the micropore volume. For this purpose, a novel desilication variant involving NaOH treatment in the presence of pore growth moderators (quaternary ammonium cations) is presented. [source]


Zeolite Catalysts with Tunable Hierarchy Factor by Pore-Growth Moderators

ADVANCED FUNCTIONAL MATERIALS, Issue 24 2009
Javier Pérez-Ramírez
Abstract The design of hierarchical zeolite catalysts is attempted through the maximization of the hierarchy factor (HF); that is, by enhancing the mesopore surface area without severe penalization of the micropore volume. For this purpose, a novel desilication variant involving NaOH treatment of ZSM-5 in the presence of quaternary ammonium cations is developed. The organic cation (TPA+ or TBA+) acts as a pore-growth moderator in the crystal by OH, -assisted silicon extraction, largely protecting the zeolite crystal during the demetallation process. The protective effect is not seen when using cations that are able to enter the micropores, such as TMA+ Engineering the pore structure at the micro- and mesolevel is essential to optimize transport properties and catalytic performance, as demonstrated in the benzene alkylation with ethylene, a representative mass-transfer limited reaction. The hierarchy factor is an appropriate tool to classify hierarchically structured materials. The latter point is of wide interest to the scientific community as it not only embraces mesoporous zeolites obtained by desilication methods but it also enables to quantitatively compare and correlate various materials obtained by different synthetic methodologies. [source]


A Customizable Instrument for Measuring the Mechanical Properties of Thin Biomedical Membranes

MACROMOLECULAR MATERIALS & ENGINEERING, Issue 10 2005
Gracián Triviño
Abstract Summary: A customized instrument has been developed as part of multidisciplinary research work relating to the development of a biodegradable vascular scaffold. This instrument aims to measure the mechanical properties of elastic and viscoelastic thin membranes with tissue engineering applications. Uniform and omni-directional pressure is applied on the whole membrane which is uniformly clamped and submerged into a liquid medium. The mechanical testing described in this study is focused on the stress-strain curves of polycaprolactone (PCL) films after different treatments. The influence of Dulbecco's modified Eagle's culture medium, L929 fibroblast culture, NaOH treatment and film thickness on the mechanical properties of PCL films was evaluated after different times. These studies show that the PCL degradation process is influenced by immersion in the culture medium, inducing an increment in the slope of the pressure-dilation curve which is indicative of an increase in the polymer stiffness. On the other hand, long NaOH treatments make PCL films have more flexible behavior. A computerized version of the instrument: (1) Electrical compressor; (2) Filter; (3) Voltage-pressure converter; (5) Pressure sensor; (6) Differential pressure sensor; (7,8) Main and auxiliary pipettes; (9) Printed circuit board; (10) Personal computer. [source]


Multiple genotyping in bovine pre-implantation embryos with whole genome amplification

ANIMAL SCIENCE JOURNAL, Issue 5 2008
Hiroki HIRAYAMA
ABSTRACT This study examined genetic diagnosis using whole genome amplification (WGA) in bovine embryos. The first experiment was conducted to compare the WGA efficiency of primer extension preamplification-PCR (PEP-PCR) and multiple displacement amplification (MDA), and to optimize the DNA extraction method. The sensitivity of SRY -specific PCR from MDA products increased when DNA of fibroblasts was extracted by a NaOH treatment instead of the conventional method (heat treatment). The detectability of SRY from PEP-PCR products was lower than that in MDA regardless of the DNA extraction method (proteinase K or NaOH treatment). Sexing and genotyping were performed using MDA products from embryo biopsy. The accuracy of PCR-based and LAMP-based sexing was 100% regardless of the amounts of biopsy. Genotyping of CL16, BND3, SCD and F11 in MDA products from 10 to 20% of trophectoderm was successful 97, 97, 95 and 95% of the time, respectively, but reduced biopsy amount (<10% of trophectoderm) decreased the accuracies (33,83%). Microsatellite markers were analyzed using MDA products from 10 to 20% of trophectoderm. In eight out of 16 microsatellites, genotypes were not contradictory among the dam, sire and embryos. In the other eight microsatellites, the inconsistency rates were 17,83%. These results indicate that MDA is useful for multiple genetic diagnoses in bovine embryos. [source]


A Customizable Instrument for Measuring the Mechanical Properties of Thin Biomedical Membranes

MACROMOLECULAR MATERIALS & ENGINEERING, Issue 10 2005
Gracián Triviño
Abstract Summary: A customized instrument has been developed as part of multidisciplinary research work relating to the development of a biodegradable vascular scaffold. This instrument aims to measure the mechanical properties of elastic and viscoelastic thin membranes with tissue engineering applications. Uniform and omni-directional pressure is applied on the whole membrane which is uniformly clamped and submerged into a liquid medium. The mechanical testing described in this study is focused on the stress-strain curves of polycaprolactone (PCL) films after different treatments. The influence of Dulbecco's modified Eagle's culture medium, L929 fibroblast culture, NaOH treatment and film thickness on the mechanical properties of PCL films was evaluated after different times. These studies show that the PCL degradation process is influenced by immersion in the culture medium, inducing an increment in the slope of the pressure-dilation curve which is indicative of an increase in the polymer stiffness. On the other hand, long NaOH treatments make PCL films have more flexible behavior. A computerized version of the instrument: (1) Electrical compressor; (2) Filter; (3) Voltage-pressure converter; (5) Pressure sensor; (6) Differential pressure sensor; (7,8) Main and auxiliary pipettes; (9) Printed circuit board; (10) Personal computer. [source]