Chemical durability of Gd2Zr2O7 transparent ceramics under different pH conditions

To study the influence of acidic and alkaline environments on the leaching behavior of Gd2Zr2O7 immobilization matrix in deep geological landfills, and to directly reflect the change of leaching behavior on its appearance, the chemical durability of Gd2Zr2O7 transparent ceramics was investigated in different pH environments in this study. The leaching results demonstrate that the normalized leaching rates in acidic environments are higher than those in alkaline and neutral environments. The transmittance of the leached transparent ceramics in the visible range decreases slightly at pH ≤ 9.0, and the macroscopic color of all samples fades after leaching. The leaching behavior leads to lattice contraction and increment of surface roughness, but it exhibits no significant effect on the surface elemental distribution. In conclusion, Gd2Zr2O7 transparent ceramics show excellent chemical durability in a weak alkaline environment, and the leaching behavior causes the discoloration of Gd2Zr2O7 transparent ceramics.

Graphene-Based Materials Immobilized within Chitosan: Applications as Adsorbents for the Removal of Aquatic Pollutants

Graphene and its derivatives, especially graphene oxide (GO), are attracting considerable interest in the fabrication of new adsorbents that have the potential to remove various pollutants that have escaped into the aquatic environment. Herein, the development of GO/chitosan (GO/CS) composites as adsorbent materials is described and reviewed. This combination is interesting as the addition of graphene to chitosan enhances its mechanical properties, while the chitosan hydrogel serves as an immobilization matrix for graphene. Following a brief description of both graphene and chitosan as independent adsorbent materials, the emerging GO/CS composites are introduced. The additional materials that have been added to the GO/CS composites, including magnetic iron oxides, chelating agents, cyclodextrins, additional adsorbents and polymeric blends, are then described and discussed. The performance of these materials in the removal of heavy metal ions, dyes and other organic molecules are discussed followed by the introduction of strategies employed in the regeneration of the GO/CS adsorbents. It is clear that, while some challenges exist, including cost, regeneration and selectivity in the adsorption process, the GO/CS composites are emerging as promising adsorbent materials.

Nanocellulose-based mechanically stable immobilization matrix for enhanced ethylene production: A framework for photosynthetic solid-state cell factories

Cell immobilization is a promising approach to create efficient photosynthetic cell factories for sustainable chemicals production. Here, we demonstrate a novel photosynthetic solid-state cell factory design for sustainable biocatalytic ethylene...

Calorimetric Sensor for Ethanol Using Ni2+-nitrilotriacetic Acid (NTA) Resin Immobilized Alcohol Dehydrogenase (ADH)

Background: A simple, fast and economic analytical method for the determination of ethanol is important for clinical, biological, forensic and physico-legal purposes. Methods: Ni2+-NTA resin was used as an immobilization matrix for the simple one-step purification/ immobilization of his6-tagged ADH. Different alcohols with a concentration range of 0.5-50% V/V, namely methanol, ethanol and propanol were measured using prepared ADH enzyme thermistor. The ethanol content of Tsingtao beer was tested as a real sample containing alcohol. Reproducibility and stability of prepared ADH enzyme thermistor were also investigated by repeated measurements. Results: In comparison to the controlled pore glass (a common used support for the immobilization of enzyme) used in thermal biosensor, the use of Ni2+-NTA resin not only led to simple one-step purification/ immobilization by his6-tagged ADH binding to Ni2+-NTA resin, but also made the immobilizing supports reusable. The prepared biosensor can be used to determine ethanol and methanol by the calorimetric measurement. A linear range of 1 -32% (V/V) and 2-20% (V/V) was observed for ethanol and methanol, respectively. The detection limits were 0.3% (V/V) and 1% (V/V) for ethanol and methanol, respectively. The tested ethanol concentration of Tsingtao beer was 4.5% V/V, which is comparable with the labeled alcohol by volume (ABV) 4.80%. Conclusion: Ni2+-NTA resin, as an immobilization matrix in ET sensor, provides a simple one-step purification/immobilization for His6-tagged recombinase and a reusable immobilization matrix. The prepared biosensor exhibits good repeatability and stability. Such a new biosensor shows great promise for rapid, simple, and cost-effective analysis of ethanol and methanol, both in qualitative and in quantitative tests.

Reed Membrane as a Novel Immobilization Matrix for the Development of an Optical Phenol Biosensor

Background: Biocompatible and easily available immobilization matrix is vital for the construction of enzyme-based biosensor. Methods: Reed membrane was selected as a novel immobilization matrix to construct an optical phenol biosensor. Tyrosinase from mushroom was immobilized in a reed membrane using glutaraldehyde as a cross-linker. The detection scheme was based on the measurement of the color intensity of the adduct resulting from the reaction of 3-methyl-2-benzothiazolinone hydrazone (MBTH) with the quinone produced from the oxidation of phenol by tyrosinase. The performance of such method including specificity, sensitivity, repeatability and practical use were validated. Results: The prepared biosensor demonstrated optimum performance at pH 6-7, temperature of 40°C and a linear response in the phenol concentration range of 5-100 μM. It also showed good operation stability for repeated measurements (over 200 times) and good storage stability after it had been kept at 4°C for 2 months. Conclusion: Reed membrane is a novel matrix for immobilization of enzyme. The prepared biosensor permits good sensitivity, reproducibility and stability. It is anticipated that reed membrane is a promising solid support for fabricating other enzyme-based biosensors.