Multi-layered Ruthenium-modified Bond Coats for Thermal Barrier Coatings

Diffusional approaches for fabrication of multi-layered Ru-modified bond coats for thermal barrier coatings have been developed via low activity chemical vapor deposition and high activity pack aluminization. Both processes yield bond coats comprising two distinct B2 layers, based on NiAl and RuAl, however, the position of these layers relative to the bond coat surface is reversed when switching processes. The structural evolution of each coating at various stages of the fabrication process has been and subsequent cyclic oxidation is presented, and the relevant interdiffusion and phase equilibria issues in are discussed. Evaluation of the oxidation behavior of these Ru-modified bond coat structures reveals that each B2 interlayer arrangement leads to the formation of α-Al 2 O 3 TGO at 1100°C, but the durability of the TGO is somewhat different and in need of further improvement in both cases

Review of experimental methods to determine spontaneous combustion susceptibility of coal – Indian context

This paper presents a critical review of the different techniques developed to investigate the susceptibility of coal to spontaneous combustion and fire. These methods may be sub-classified into the two following areas: (1) Basic coal characterisation studies (chemical constituents) and their influence on spontaneous combustion susceptibility. (2) Test methods to assess the susceptibility of a coal sample to spontaneous combustion. This is followed by a critical literature review that summarises previous research with special emphasis given to Indian coals

Applications of Crossing Point Temperature for Determining the Spontaneous Heating Characteristics of Coals

Attempts have been made to classify various Indian coals with respect to their susceptibility to spontaneous combustion based on their crossing point temperature. Over fifty Indian coals were used during this investigation and it could be concluded that crossing point temperature can be gainfully used for this purpose. In general, higher crossing point temperature signifies lower susceptibility, whereas lower crossing point temperature indicates higher susceptibility to heating. Both the crossing point temperature as well as the slope of the time-temperature curve should be taken into consideration for determining the degree of susceptibility of coals to spontaneous combustion. Coals which show low crossing point temperature and a sudden sharp rise in the slope of the time-temperature curve may be considered to be highly vulnerable to spontaneous heating. It was also observed that higher rank coals are normally less susceptible to spontaneous combustion than lower rank coals

Effect of Moisture on the Self Heating Characteristics of Coal

The critical oxidation temperature or the crossing point temperature is often used as a parameter in studying the self heating characteristics of coals. Although the mechanism of auto-oxidation is not fully understood as yet, it is known that the moisture plays a very important role in the reaction. The paper report the influence of moisture in the self heating characteristics as investigated from the changes in the critical oxidation temperature of coals. The investigation also includes the effect of humid air (i.e. at various percentages of relative humidity). It has been observed that the self heating characteristic of coal is influenced by both the sources of moisture i.e. the moisture in coal and the humidity of air. However, the moisture in coal plays a more signification role during spontaneous combustion

An approach to assessing the status of sealed-off fires by examination of fire indices

The advantages and disadvantages of different fire indices in common use, such as CO/O2 deficiency (def.)%, CO2/O2 def.% and CO/CO2 percentage, as well as those proposed in the literature such as the desorbed hydrocarbon index, the CO—residual gas relationship and the C/H ratio of the products of combustion, are discussed in terms of their applicability for determining the extent and intensity of underground sealed fires. Five cases of different types of fires are studied and examined using the above indices. It is inferred that characterisation of fires should be made from fire indices, such as the C/H ratio, CO/O2 def.% and the CO/CO2 percentage, temperature profile studies, pressure differential measurements in stopes and spontaneous heating characteristics of the coal concerned in relation to other mining parameters. Values of C/H ratio above 3 or 4, values of the CO/O2 def.% of > 0.5 and values of CO/CO2 of > 2 are indicative of initiation of active fires. A C/H ratio of ⩾ 20 indicates a blazing fire where wooden props may be burning

Herbal remedies against Huntington's disease: Preclinical evidences and future directions

Herbal medicines, or phytochemicals can treat various neurological disorders, and is actually preferred over synthetic drugs due to their lower cost, negligible side effects, easy availability and therapeutic efficiency. This article lists a total of 13 plant extracts, 27 plant derived natural compounds and 3 herbal formulations that were found to therapeutically cure Huntington's Disease, mainly by eliminating the toxic mHtt proteins(the product of the mutant gene responsible for HD). The various plant compounds, fractions, extracts and herbal formulations were summarized from popular scientific search engines and then analyzed on the basis of their source and bioactivity. To understand the behavioral, biochemical and morphological changes caused by HD, experimental models like 3-NP and transgenic animal models like rats, mice, Drosophila and Caenorhaditis elegans were used. Plants such as Bacopa monnieri, Celastrus paniculatus, Centella asiatica, Gastrodia elata, Panax ginseng, and Withania somnifera are some examples that possess anti-HD properties. Some examples of promising plant compounds possessing similar properties are fisetin, curcumin, hesperidin, trehalose, onjisaponin B, sesamol, resveratrol, kaempferol and melatonin. Herbal formulations discussed here are B307, CLMT and YGS. These are proved to be more beneficial than single herbs because they can regulate more targets. However, detailed study and further research should be conducted to determine the therapeutic efficacy of herbal extracts and compounds in HD models. © 2022 Elsevier Inc. All rights reserved