Pengaruh Thermal Shock dan Komposisi Evaporation Boats, Semen Tahan Api, dan Pasir Silika terhadap Kekuatan Impact dan Foto Makro Lining Refractory

<p>The thermal shock behavior of ceramic refractory materials is of particular interest. Refractory materials are submitted to local temperature gradients in service that originate thermal stresses and thermal shock damage to the material. However, thermal shock treatment on the refractory made from evaporation boat waste is not well documented. The purpose of this study is to determine the effect of thermal shock on the strength of refractory with various compositions. In this study, the refractory was made using 100% refractory cement (sample 1). For Sample 2, the refractory was made from a mixture of refactory cement and evaporation boats waste, each of 50%: 50%. Meanwhile, specimen 3 of the refractory is made from a mixture of refactory cement, evaporation boat waste, and silica sand of 40%: 50%: 10%, respectively. The Thermal shock treatment is carried out at a temperature range of 100 – 700^oC for each specimen. The effect of thermal shock treatment on the mechanical properties of each refractory specimen was investigated using the impact and macrography test. Temperature variations in thermal shock have different effects on the level of impact strength on impact test specimens. The lowest strength was 0,012297735 J/mm²at thermal shock 700⁰C in sample 3, and the highest impact strength was 0,03928934 J/mm² at 400^oC thermal shock temperature in sample 2. The macrographic examination shows the higher the thermal shock temperature, the greater the fracture produced when the impact test is carried out. This is because the hardness of the refractory material increases.</p>

Return temperature after heat shock affects the production of tetraploids in the yellowtail tetra Astyanax altiparanae

Summary The aim of this study was to evaluate different post-shock temperatures for tetraploid induction in the yellowtail tetra Astyanax altiparanae. Newly fertilized eggs were divided into four groups, three were submitted to heat shock (40°C for 2 min) at 24 min post-fertilization (mpf) and another group remained without shock (control). Groups submitted to temperature shock were further separated at the following temperatures: 22°C, 26°C and 28°C. Survival among embryonic development was counted and at hatching the ploidy was analyzed by flow cytometry. The results showed that the post-shock temperature affects the parameters analyzed and, therefore, must be considered for optimization of the production of tetraploid in A. altiparanae. Those data are innovative and could be used in future studies of basic biology in this species.

Estimate of Plasma Temperatures Across a CME-Driven Shock from a Comparison Between EUV and Radio Data

In this work, we analyze the evolution of an EUV wave front associated with a solar eruption that occurred on 30 October 2014, with the aim of investigating, through differential emission measure (DEM) analysis, the physical properties of the plasma compressed and heated by the accompanying shock wave. The EUV wave was observed by the Atmospheric Imaging Assembly (AIA) onboard the Solar Dynamics Observatory (SDO) and was accompanied by the detection of a metric Type II burst observed by ground-based radio spectrographs. The EUV signature of the shock wave was also detected in two of the AIA channels centered at 193 Å and 211 Å as an EUV intensity enhancement propagating ahead of the associated CME. The density compression ratio $X$ X of the shock as inferred from the analysis of the EUV data is $X \approx 1.23$ X ≈ 1.23 , in agreement with independent estimates obtained from the analysis of the Type II band-splitting of the radio data and inferred by adopting the upstream–downstream interpretation. By applying the Rankine–Hugoniot jump conditions under the hypothesis of a perpendicular shock, we also estimate the temperature ratio as $T_{\mathrm{D}}/T_{\mathrm{U}} \approx 1.55$ T D / T U ≈ 1.55 and the post-shock temperature as $T_{\mathrm{D}}\approx 2.75$ T D ≈ 2.75 MK. The modest compression ratio and temperature jump derived from the EUV analysis at the shock passage are typical of weak coronal shocks.

A Study of Shock-Metamorphic Features of Feldspars from the Xiuyan Impact Crater

Feldspar is the most abundant mineral in the Earth’s crust and is widely distributed in rocks. It is also one of the most common minerals in meteorites. Shock-metamorphic features in feldspar are widely used to calibrate the temperature and pressure of shock events and can also provide clues for searching for impact craters on Earth. In this study, shocked alkali feldspars in the lithic breccia and suevite from Xiuyan Impact Crater were investigated using polarizing optical microscopes, Raman spectroscopy and electron microprobes to better constrain the shock history of this crater. For this study, feldspar grains occurring in gneiss clasts in the impact breccia and four shock stages were identified, e.g., weakly shocked feldspar, moderately shocked feldspar, strongly shocked feldspar, and whole rock melting. According to the shock classification system for alkali feldspar and felsic rocks, we estimated the shock pressure (SP) and post-shock temperature (PST) histories of these gneiss clasts. Weakly shocked feldspars display irregular fractures and undulatory extinction, and their shock stage is F-S2, which indicates that SP and PST are from ~5 to ~14 GPa and ~100 °C, respectively. Moderately shocked feldspars show planar deformation features and are partially transformed into diaplectic glass, which indicates that the F-S5 shock stage of SP and PST is from ~32 to ~45 GPa and 300–900 °C. Strongly shocked feldspars that occur as vesicular glass indicate a shock stage of F-S6, and the SP and PST are 45–60 GPa and 900–1500 °C, respectively. The whole felsic rock melting occurs as mixed melt glass clast and belongs to the F-S7 stage, and SP and PST are >60 GPa and >1500 °C, respectively.