Enzyme-inorganic nanoporous materials: Stabilization of proteins intercalated in α-zirconium(IV) phosphate by a denaturant

Improving the stability of proteins and enzymes at solid–liquid interfaces is challenging and it has important implications in biocatalysis and biosensors. Here, we report that moderate concentrations of urea stabilize heme proteins, such as met-hemoglobin (Hb) or met-myoglobin (Mb) bound to α-zirconium phosphate (α-ZrP). The half-life of Hb intercalated in the galleries of α-ZrP, for example, increased from 127 h (no urea) to >235 h (2 M urea). The peroxidase-like activity of Hb intercalated in α-ZrP was also improved by the addition of urea, and the product yields increased from 44% (no urea) to 79% (2 M urea). These improvements are not limited to Hb, and similar results also observed with Mb. Urea also inhibited the dithionite reduction of the ferric form of the intercalated heme proteins to their corresponding ferrous forms but not the oxidation of the ferric form to the corresponding high valent iron-oxo species. These observations open new possibilities to control the properties of immobilized proteins.     

Pulsating hydromagnetic flow of Casson fluid in a vertical channel filled with non-Darcian porous medium

This paper analyzes the Joule heating, Dufour number, and Soret number effects on hydromagnetic pulsatile flow of a Casson fluid in a vertical channel filled with a non-Darcian porous medium. The governing partial differential equations (PDEs) of the Casson fluid flow are transformed to ordinary differential equations (ODEs) using perturbation technique and solved by employing shooting method with Runge–Kutta (R–K) fourth-order technique using MATHEMATICA function NDSolve. The influence of Forchheimer number, Casson fluid parameter, Dufour number, radiation parameter, and Soret number on flow variables has been studied and the numerical results obtained are presented. The results reveal that the velocity rises with the rise of Darcy number, whereas it decreases for a given rise in the Forchheimer number. Furthermore, the temperature distribution enhances by increasing the Dufour number.     

Bio-oil Production from an Oilseed By-product: Fixed-bed Pyrolysis of Olive Cake

Abstract

A study of pyrolysis of olive cake at the temperature range from 400°C to 700°C has been carried out. The experiments were performed in a laboratory scale tubular reactor under nitrogen atmosphere. The yields of derived gases, liquids, and char were determined in relation to pyrolysis temperature and sweeping gas flow rates, at heating rates of about 300°C min^?1. As the pyrolysis temperature was increased, the percentage mass of char decreased whilst gas product increased. The oil products increased to a maximum value of ～39.4 wt% of dry ash free biomass at a pyrolysis temperature of about 550°C in a nitrogen atmosphere with flow rate of 100 mL min^?1 and with a heating rate of 300°C min^?1. Results showed that the bio-oil obtained under the optimum conditions is a useful substitute for fossil fuels or chemicals.     

A review of recent laboratory research and commercial developments in fast pyrolysis and upgrading

Robust alternative technology choices are required in the paradigm shift from the current crude oil-reliant transport fuel platform to a sustainable, more flexible transport infrastructure. In this vein, fast pyrolysis of biomass and upgrading of the product is deemed to have potential as a technology solution. The objective of this review is to provide an update on recent laboratory research and commercial developments in fast pyrolysis and upgrading techniques. Fast pyrolysis is a relatively mature technology and is on the verge of commercialisation. While upgrading of bio-oils is currently confined to laboratory and pilot scale, an increased understanding of upgrading processes has been achieved in recent times.     

Geometry design model of a precise form-milling cutter based on the machining characteristics

This paper presents a new approach to design a form milling cutter for precisely obtaining the complex free-form surfaces. In this study, the intersection point of the rake surface, helix flute and clearance flank is appropriately defined due to its significant role in the design and grinding performance. The angle-solid-block analysis is developed to establish the new cutter geometry model. Hence, a new form-milling cutter satisfying the requirements of machining characteristics of workpiece can be designed. In addition, the cutter geometric model can be adopted to map out the measuring strategy with minimum measured points to attain the exact geometric feature of cutter.     

Production and characterization of a set of mouse-human chimeric immunoglobulin G (IgG) subclass and IgA monoclonal antibodies with identical variable regions specific for Pseudomonas aeruginosa serogroup O6 lipopolysaccharide

The heavy- and light-chain variable regions from a murine monoclonal antibody that recognize Pseudomonas aeruginosa serogroup O6 lipopolysaccharide (LPS) were used to generate a series of chimeric mouse-human monoclonal antibodies with identical variable regions. The murine variable-region gene segments were cloned into an immunoglobulin (Ig) cDNA expression vector that contained the human kappa light-chain and IgG1 constant regions. The IgG1 heavy-chain constant region was then replaced with the human IgG2, IgG3, IgG4, or IgA1 heavy-chain constant region. The five different expression vectors were transfected into Chinese hamster ovary cells for antibody production. The chimeric antibodies exhibited immunoreactivity and affinity similar to that of the parental murine IgG antibody toward whole cells of a serogroup O6 strain. In vitro complement deposition assays demonstrated that the chimeric IgG4 and IgA antibodies did not mediate the deposition of complement component C3 onto the surface of either purified LPS or whole bacteria. The chimeric IgG1 and IgG3 antibodies were similar in their ability to deposit C3 onto the surface of both bacteria and LPS, while IgG2 antibody was more effective at depositing C3 onto the surface of bacteria than onto purified LPS. The pattern of opsonophagocytic activity of the chimeric monoclonal antibodies was similar to that of complement deposition onto bacterial cells in that the chimeric IgG1 and IgG3 had the highest opsonic activity. Although IgG2 deposited more C3 onto the bacterial surface than did IgG4 or IgA, all three of these isotypes had low opsonic activity against the serogroup O6 target strain. This series of related antibodies will help reveal functional differences in efficacy among protective antibodies to P. aeruginosa and will be critical for defining the optimal formulation of either a vaccine for active immunization or a polyclonal intravenous IgG or monoclonal antibody cocktail for passive immunotherapy.     

Denaturation and renaturation of self-assembled yeast iso-1-cytochrome c on Au

We have made surface plasmon resonance (SPR) measurements of yeast iso-1-cytochrome c (Cyt c) on a gold surface. Angle-resolved SPR curves are recorded as a function of urea concentration before and after self-assembly of the Cyt c. Exposure to a urea solution causes denaturation of Cyt c, which shifts the minimum in the SPR curve to a larger angle and decreases the signal amplitude. The Gibbs free energy change for denaturation of the protein on Au is calculated from the change of the SPR signal amplitude with urea concentration. We find that (1) Cyt c can be reversibly denatured and renatured, depending on the urea concentration, and (2) the Gibbs free energy change for denaturation of Cyt c on Au surface in water, DeltaG degrees (water), is 1.5 kcal/mol, which is approximately 4 times less than that in bulk solution.     

Effect of EGFR on SQSTM1 Expression in Malignancy and Tumor Progression of Oral Squamous Cell Carcinoma

Oral squamous cell carcinoma (OSCC) is one of the most common types of malignant tumor. Sequestosome 1 (SQSTM1) serves as an adaptor of autophagy for degrading protein aggregates. The regulation of autophagy by EGFR and its clinical impacts are indicated in various types of cancer. However, the association of EGFR and SQSTM1 in OSCC is still unknown. Our results show that the expression levels of SQSTM1 and EGFR proteins are higher in tumor tissues than in the corresponding tumor-adjacent (CTAN) tissues of OSCC patients. The expression levels of SQSTM1 were positively associated with the EGFR expression level. High co-expression of SQSTM1 and EGFR is associated with poor prognosis in OSCC patients. Moreover, SQSTM1 expression is decreased in EGFR-knockdown cells. Cell growth and invasion/migration are also decreased in cells with single/combined knockdowns of EGFR and SQSTM1 or in SQSTM1-knockdown cells without EGFR kinase inhibitor Lapatinib treatment compared to that in scrambled cells. However, cell growth and invasion/metastasis were not significantly different between the scrambled cells and SQSTM1-knockdown cells in the presence of Lapatinib. This study is the first to indicate the biological roles and clinical significance of SQSTM1 regulation by EGFR in OSCC.     

ZnO microparticle-loaded chitosan/poly(vinyl alcohol)/acacia gum nanosphere-based nanocomposite thin film wound dressings for accelerated wound healing

The present study deals with the development of novel ZnO microparticle-loaded chitosan/poly(vinyl alcohol)/acacia gum nanosphere-based nanocomposite thin films through electrospraying and evaluation of their potential use in wound healing applications for skin. ZnO microparticles were synthesized and used as bioactive agents. Morphology, size distribution, structure, and dispersion of the synthesized ZnO microparticles were analyzed by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, and transmission electron microscopy (TEM). ZnO microparticles were incorporated into the ternary nanocomposite films by electrospraying technique. Thermogravimetric analyses reveal that incorporation of ZnO microparticles into the nanocomposite structure improves the thermal stability. Mechanical analyses show that tensile strength reaches to the maximum value of 12.75 MPa with 0.6 wt % ZnO content. SEM and TEM micrographs demonstrate that the nanocomposite films consist of nanospheres with nanocapsular structures whose sizes are mostly between 250 and 550 nm. Viability tests established prevailing cellular performance of the fibroblasts on 0.6 wt % ZnO microparticle-loaded nanocomposite films with a viability percentage of 160% compared to the control group. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 48445.     

Economic restructuring in Eastern Europe and acid rain abatement strategies

Acid rain abatement in Europe are currently being discussed in view of the expiration of the Helsinki Protocol on SO₂ emission reduction. The changing energy situation in Eastern European countries is expected to have an influence on the deposition pattern in Europe. The paper presents a consistent energy scenario for Eastern European countries and compares optimal strategies to reduce SO₂ emissions. These strategies are based on runs with the RAINS model in which environmental targets have been set based on critical loads for sulphur. The analysis shows that economic restructuring and efficiency improvements in Eastern European countries, as well as in Western Europe, may result in significantly lower sulphur abatement. costs. Potential assistance to Eastern Europe to guarantee desired environmental standards in Western countries should therefore focus not only on providing emission control devices but also on the success of the economic transition process.