Interplay of isoform 1N4R tau protein and amyloid-β peptide fragment 25-35 in reducing and non-reducing conditions

Amyloid-β (Aβ) peptide and tau protein are two hallmark proteins in Alzheimer's disease (AD), however the parameters which mediate the abnormal aggregation of Aβ and tau have not been fully discovered. Here, we have provided an optimum method to purify tau protein isoform 1N4R by using Ni-NTA agarose chromatography under denaturing condition. The biochemical and biophysical properties of the purified protein was further characterized using in vitro tau filament assembly, tubulin polymerization assay, circular dichroism (CD) spectroscopy and atomic force microscopy. Afterwards, we investigated the effect of tau protein on aggregation of Aβ (25–35) peptide using microscopic imaging and cell viability assay. Incubation of tau at physiologic and supra-physiologic concentrations with Aβ25–35 for forty days under reducing and non-reducing conditions revealed formation of two types of aggregates with distinct morphologies and dimensions. In non-reducing condition, the co-incubated sample showed granular aggregates, while in reducing condition, they formed annular protofibrils. Results from cell viability assay revealed the increased cell viability for the co-incubated sample. Therefore, the disassembling action shown by tau protein on Aβ25–35 suggests the possibility that tau may have a protective role in preventing Aβ peptide from acquiring the cytotoxic, aggregated form against oxidative stress damages.

FWHM Calculation of Zircon Gem-Materials before and after Thermal Enhancement

Zircon samples from Ubon Ratchathani, Thailand; Rattanakiri, Cambodia and Dak Nong, Vietnam change their color from light brown and reddish-brown to blue color after thermal enhancement at 1000 ๐C in reducing condition for 60 min. The high temperature is one of the factors for the zircon structure to recrystallize. The objective of this study is to describe the crystal structure of zircon samples before and after thermal enhancement. Zircon is a metamict mineral whose structure is destroyed by some trace elements. There are radioactive elements such as U and Th in the zircon structure. In this study, Raman spectroscopy was used to analyze the molecular vibration in zircon structure before and after thermal enhancement. As a result, the Raman spectra of zircon samples after thermal enhancement show the Raman shift at peak position of V3(SiO4) stretching around 1008cm-1to higher wavenumber concerning to the full width at half maximum (FWHM) values calculated by PyMCA software. The results could be summarized that the metamict zircon will be recrystallized to the crystalline zircon after thermal enhancement. The advantage of this study is about the identification of zircon before and after thermal enhancement.

Temperature Measuring System in High Temperature Carbon Reducing Environment

An essential material testing facility (EMTF) used for pebble bed effective conductivity measuring experiment of high temperature gas-cooled reactor was developed. As required, temperature measuring points were arranged in EMTF to monitor the temperature field. The maximum test temperature in EMTF would be 1600°C. The main part of EMTF was made of graphite and carbon felt, hence the measuring points were in strong carbon reducing environment, of which some were embedded in the carbon felt. The material choice and structure design of the thermal couples were introduced. In the high temperature region, our specially designed tungsten-rhenium thermocouple was used. For the comparison, some imported tungsten-rhenium thermocouples were also used. The distributive data acquisition system was made of IMP form Solartron in England, which with industrial computer constructs a data acquisition and control system. The software was programmed with configuration software of Sunwayland Forcecontrol. Finally, the measuring results in each part of EMTF were given, such as the heater, testing zone, thermal insulating layers. The experimental result showed that the designed temperature measuring system worked stably and reliably, which could finish the temperature acquisition task in 1600°C high temperature carbon reducing condition. After the experiment, the thermal couples experiencing high temperature in carbon reducing condition were removed out to analyze the structural change and study the damaged condition.