Osteogenic Cells Derived From Embryonic Stem Cells Produced Bone Nodules in Three-Dimensional Scaffolds

An approach for 3D bone tissue generation from embryonic stem (ES) cells was investigated. The ES cells were induced to differentiate into osteogenic precursors, capable of proliferating and subsequently differentiating into bone-forming cells. The differentiated cells and the seeded scaffolds were characterized using von Kossa and Alizarin Red staining, electron microscopy, and RT-PCR analysis. The results demonstrated that ES-derived bone-forming cells attached to and colonized the biocompatible and biodegradable scaffolds. Furthermore, these cells produced bone nodules when grown for 3–4 weeks in mineralization medium containing ascorbic acid and beta-glycerophosphate both in tissue culture plates and in scaffolds. The differentiated cells also expressed osteospecific markers when grown both in the culture plates and in 3D scaffolds. Osteogenic cells expressed alkaline phosphatase, osteocalcin, and osteopontin, but not an ES cell-specific marker, oct-4. These findings suggest that ES cell can be used for in vitro tissue engineering and cultivation of graftable skeletal structures

Structure of a model TiO2 photocatalytic interface

The interaction of water with TiO2 is crucial to many of its practical applications, including photocatalytic water splitting. Following the first demonstration of this phenomenon 40 years ago there have been numerous studies of the rutile single-crystal TiO2(110) interface with water. This has provided an atomic-level understanding of the water-TiO2 interaction. However, nearly all of the previous studies of water/TiO2 interfaces involve water in the vapour phase. Here, we explore the interfacial structure between liquid water and a rutile TiO2(110) surface pre-characterized at the atomic level. Scanning tunnelling microscopy and surface X-ray diffraction are used to determine the structure, which is comprised of an ordered array of hydroxyl molecules with molecular water in the second layer. Static and dynamic density functional theory calculations suggest that a possible mechanism for formation of the hydroxyl overlayer involves the mixed adsorption of O2 and H2O on a partially defected surface. The quantitative structural properties derived here provide a basis with which to explore the atomistic properties and hence mechanisms involved in TiO2 photocatalysis

Degradation mechanism and toxicity reduction of methyl orange dye by a newly isolated bacterium Pseudomonas aeruginosa MZ520730

Methyl orange (MO) dye is recalcitrant in nature, hard to degrade and if released into the soil and aquatic resources could cause serious threats on environment and human health. MO is toxic to plant growth. Bacterial treatment may be a sustainable solution for its degradation and decolourization. In this work, a bacterium (RKS6) was isolated from textile industry wastewater and sludge samples and identified as Pseudomonas aeruginosa based on the 16S rRNA gene sequencing analysis. RKS6 showed more than 99% decolorization of MO dye (100 mg/l) and 96% reduction of total organic carbon (TOC) within 12 h, at 30 °C, pH 7 at static conditions. RKS6 also produced MnP enzyme of molecular weight ∼53 kDa as characterized by the SDS-PAGE analysis. Further, LC-MS analysis showed that MO dye was degraded into 4-[(4-aminophenyl) diazenyl] benzene sulfonate, 4, 2-((dihydroxymethyl) hyrazono-4) 5-benzene sulfonate, 4-(triazan-2-yl) benzene sulfonic, water and carbon dioxide by RKS6. Toxicity assessment showed that the solution treated by the bacterium allowed 90% seed germination indicating that RKS6 was effective in mineralization and detoxification of MO dye and can be effectively used in industrial wastewater treatment

Large NcN_c Universality of The Baryon Isgur--Wise Form Factor: The Group Theoretical Approach

In a previous article, it has been proved under the framework of chiral soliton model that the same Isgur--Wise form factor describes the semileptonic $\Lambda_b\to\Lambda_c$ and $\Sigma^{(*)}_b\to\Sigma^{(*)}_c$ decays in the large $N_c$ limit. It is shown here that this result is in fact independent of the chiral soliton model and is solely the consequence of the spin-flavor SU(4) symmetry which arises in the baryon sector in the large $N_c$ limit.Comment: 10 pages in REVTeX, no figure

A high-efficiency spin-resolved phototemission spectrometer combining time-of-flight spectroscopy with exchange-scattering polarimetry

We describe a spin-resolved electron spectrometer capable of uniquely efficient and high energy resolution measurements. Spin analysis is obtained through polarimetry based on low-energy exchange scattering from a ferromagnetic thin-film target. This approach can achieve a similar analyzing power (Sherman function) as state-of-the-art Mott scattering polarimeters, but with as much as 100 times improved efficiency due to increased reflectivity. Performance is further enhanced by integrating the polarimeter into a time-of-flight (TOF) based energy analysis scheme with a precise and flexible electrostatic lens system. The parallel acquisition of a range of electron kinetic energies afforded by the TOF approach results in an order of magnitude (or more) increase in efficiency compared to hemispherical analyzers. The lens system additionally features a 90{\deg} bandpass filter, which by removing unwanted parts of the photoelectron distribution allows the TOF technique to be performed at low electron drift energy and high energy resolution within a wide range of experimental parameters. The spectrometer is ideally suited for high-resolution spin- and angle-resolved photoemission spectroscopy (spin-ARPES), and initial results are shown. The TOF approach makes the spectrometer especially ideal for time-resolved spin-ARPES experiments.Comment: 16 pages, 11 figure

Structural changes of thermal sprayed graphene nano platelets film into amorphous carbon under sliding wear

© 2020 The Authors Graphene has become a promising candidate to protect surfaces against friction due to its strength and lubricating ability. In this study, graphene nano platelets (GNP) thin films have been deposited onto stainless steel substrates by axially injecting GNP suspension through high velocity oxy fuel thermal spray gun. The tribological performance of the films under dry sliding wear was investigated through unlubricated ball on disc sliding wear test against a sintered alumina counter body ball under 5 N load. The understanding of the behaviour of the GNPs under sliding wear will be useful for improving the performance of graphene-based coatings which are in demand for wear resistant applications. A film was deposited showing significant improvements in friction with coefficient of friction value reduced by 7 times compared to uncoated stainless steel, even for a discontinuous film. A morphological analysis shows sliding wear led to change in particle shape from angular flakes into randomly oriented circles. Interatomic bonding and structural analysis performed reveals oxidation defect formations during wear test. Structural degradation and oxidation of GNPs during the process led to formation of amorphous carbon from graphene. Amorphous carbon formation reduces the lubricating ability and strength of the film, leading to failure