Purification of peroxidase from Amsonia orientalis by three-phase partitioning and its biochemical characterization

The present work describes the purification and characterization of peroxidase from the medicinal plant, Amsonia orientalis, for the first time. The activity recovery for peroxidase was 162% with 12.5-fold purification. Optimal purification parameters were 20% (w/v) (NH₄)₂SO₄ saturation at pH 6.0 and 25°C with 1.0:1.0 (v/v) ratio of crude extract to t-butanol ratio for 30 min. The molecular mass of the enzyme was found to be ca. 59 kDa. Peroxidase showed K_m values of 1.88 and 2.0 mM for pyrogallol and hydrogen peroxide, respectively. FeSO₄, CuSO₄, HgCl₂, MnSO₄ and MgSO₄ did not inhibit the enzyme activity.     

Appraising the methods accounting for 3D tunnelling effects in 2D plane strain FE analysis

Numerical analysis is widely used method in geotechnical engineering when calculating and predicting soil and rock behaviour under different loading and excavation conditions. For instance, simulation of tunnelling using 2D or 3D finite element (FE) analyses can often calculate any deformations and stress redistributions due to tunnelling operations without constructing real trial tunnels. Modelling the excavation process in 2D plane strain analysis, however, requires an approach that can consider 3D tunnelling effect as a result of volume loss. In addition, modelling shotcrete or similar support measures, using either beam elements, solid continuum elements or other special elements are needed to be adopted. Therefore, convergence-confinement, stiffness reduction, disk calculation and hypothetical modulus of elasticity (HME) soft lining approaches have been employed in the numerical analysis. Moreover, compatibility of each method with beam and solid continuum element models in 2D FE analysis was investigated. Thus, eight plane strain, non-linear FE analyses of tunnel construction in London Clay were performed and the results are presented and discussed in this article.     

Proton Transport in Electrospun Hybrid Organic–Inorganic Membranes: An Illuminating Paradox

Chemistry and processing have to be judiciously combined to structure the membranes at various length scales to achieve efficient properties for polymer electrolyte membrane fuel cell to make it competitive for transport. Characterizing the proton transport at various length and space scales and understanding the interplays between the nanostructuration, the confinement effect, the interactions, and connectivity are consequently needed. The goal here is to study the proton transport in multiscale, electrospun hybrid membranes (EHMs) at length scales ranging from molecular to macroscopic by using complementary techniques, i.e., electrochemical impedance spectroscopy, pulsed field gradient‐NMR spectroscopy, and quasielastic neutron scattering. Highly conductive hybrid membranes (EHMs) are produced and their performances are rationalized taken into account the balances existing between local interaction driven mobility and large‐scale connectivity effects. It is found that the water diffusion coefficient can be locally decreased (2 × 10^?6 cm² s^?1) due to weak interactions with the silica network, but the macroscopic diffusion coefficient is still high (9.6 × 10^?6 cm² s^?1). These results highlight that EHMs have slow dynamics at the local scale without being detrimental for long‐range proton transport. This is possible through the nanostructuration of the membranes, controlled via processing and chemistry.     

Determination of polyphenolic constituents and biological activities of bark extracts from different Pinus species

BACKGROUND: The most common commercially available pine bark extract is Pycnogenol^®, a standardised extract of Pinus maritima, which has been reported to have cardiovascular benefits and enhance microcirculation. The present study was conducted to determine the chemical composition of four pine bark extracts, assess their biological activities and to compare the results with Pycnogenol^®. RESULTS: The Pinus species were analysed by LC and LC‐MS; extracts of P. brutia and P. nigra showed higher levels of phenolic constituents compared to P. sylvestris and P. pinea. In particular, P. brutia contained extremely high concentrations of taxifolin (18.5%). The highest radical scavenging activities were attained with P. pinea (88.6%), P. nigra (87.2%) and P. brutia (86.4%) bark extracts. Additionally, anticarcinogenic effects of the extracts and their kinetics were determined in four cell lines including human prostate (PC‐3, DU 145, LNCaP) and breast adenocarcinoma (MCF7) by the MTT assay. Cell viability was reduced to 40% by extracts of P. pinea, and P. sylvestris in PC‐3 cells showing a similar effect like the positive control, CPT‐11. CONCLUSION: Pinus species other than P. maritima definitively possess high biological activities, and therefore present a huge potential to be utilised in the food and the pharmaceutical industries. Copyright © 2009 Society of Chemical Industry     

A complementary study on novel PdAuCo catalysts: Synthesis,characterization, direct formic acid fuel cell application,and exergy analysis

At present, Pd containing (10–40 wt%) multiwall carbon nanotube (MWCNT) supported Pd monometallic, Pd:Au bimetallic, and PdAuCo trimetallic catalysts are prepared via NaBH₄ reduction method to examine their formic acid electrooxidation activities and direct formic acid fuel cell performances (DFAFCs) when used as anode catalysts. These catalysts are characterized by advanced analytical techniques as N₂ adsorption and desorption, XRD, SAXS, SEM-EDX, and TEM. Electronic state of Pd changes by the addition of Au and Co. Moreover, formic acid electrooxidation activities of these catalysts measured by CV indicates that particle size changes in wide range play a major role in the formic acid electrochemical oxidation activity, ascribed the strong structure sensitivity of formic acid electrooxidation reaction. PdAuCo (80:10:10)/MWCNT catalyst displays the most significant current density increase. On the other hand, lower CO stripping peak potential obtained for PdAuCo (80:10:10)/MWCNT catalyst, attributed to the awakening of the Pd-adsorbate bond strength down to its optimum value, which favors higher electrochemical activity. DFAFCs performance tests and exergy analysis reveal that fuel cell performances increase with the addition of Au and Co which can be attributed to synergetic effect. Furthermore, temperature strongly influences the performance of formic acid fuel cell.     

Differences observed in properties of ternary NiCoFe films electrodeposited at low and high pH

Ternary NiCoFe films were potentiostatically electrodeposited from the electrolytes with low (3.0) and high (3.6) pH levels, and differences in their compositional, structural, magnetic and magnetoresistance properties were studied. The compositional analysis demonstrated that the Ni content in the films decreased, and Co and Fe content increased while electrolyte pH was changed from low to high level. The structural analysis of the films was carried out using the X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques. The XRD data revealed that the films have a strong (111) texture of the face-centred cubic (fcc) structure at low pH, while for the films at high pH a mixture of dominantly fcc and hexagonal closed packed structure was observed. The SEM studies showed that films grown at low pH level had comparatively larger grains than those at high pH. The magnetic characteristics studied by a vibrating sample magnetometer and magnetotransport properties were seen to be changed by the electrolyte pH. However, all films have in-plane magnetic anisotropy. The differences observed in the magnetic and magnetotransport properties were attributed to the microstructural changes caused by the electrolyte pH.     

Transient protein-protein interactions

Transient complexes are crucial for diverse biological processes such as biochemical pathways and signaling cascades in the cell. Here, we give an overview of the transient interactions; the importance of transient interactions as drug targets; and the structural characterization of transient protein-protein complexes based on the geometrical and physicochemical features of the transient complexes' interfaces. To better understand and eventually design transient protein-protein interactions (TPPIs), a molecular perspective of the protein-protein interfaces is necessary. Obtaining high-quality structures of protein-protein interactions could be one way of achieving this goal. After introducing the association kinetics of TPPIs, we elaborate on the experimental techniques detecting TPPIs in combination with the computational methods which classify transient and/or non-obligate complexes. In this review, currently available databases and servers that can be used to identify and predict TPPIs are also compiled.