Three-stage metamorphic history of a whiteschist from Sar e Sang,Afghanistan, as part of a former evaporite deposit

Small volumes (in the cm³ range) of a talc-kyanite schist exhibit mosaic equilibria characterized by mineral assemblages conventionally attributed to vastly different pressure temperature conditions of metamorphism. On the basis of petrographic and microprobe studies these assemblages are attributed to three consecutive stages of metamorphism of a chemically exceptional rock composition falling largely into the model system MgO-Al₂O₃-SiO₂-H₂O. Stage 1 typified by Mg chlorite-quartz-talc and some paragonite was followed during stage 2 by talc-kyanite, Mg gedrite-quartz, and the growth of large dravites. In stage 3 pure Mg cordierite formed with or without corundum and/or talc, and kyanite was partly converted into sillimanite. Pressures and temperature during this final stage of metamorphism were probably near 5–6 kb, 640 ° C. The preservation of this succession of mineral assemblages related to each other through isochemical reactions suggests that the main factors governing the metamorphic history of this whitheschist were compositional changes of the coexisting fluids with time, whereas pressure temperature variations may be subordinate. In the Sar e Sang area such chemical variations of the metamorphic fluids are probably caused by progressive metamorphism and mobilization of a former evaporite deposit. Microprobe analyses of the phases gedrite and talc indicate variable degrees of sodium incorporation into these phases according to the substitution NaAl→Si.     

The propagation of elastic waves from moving normal point loads in layered media

The steady-state response is determined of elastic layered media to buried moving normal point loads. The exact solution appears as a superposition of infinitely many rays, each of them given in closed form, in terms of algebraic functions. The solution obtained yields a local behaviour corresponding to the unbounded-space solution. The unbounded-space problem was previously solved byEason, Fulton andSneddon [8] and their solution is utilized for the present solution by superposing it on secondary fields so as to satisfy the boundary conditions. The secondary fields are obtained by the method of the differential transferm described below.     

Groundwater Storage through Rain Water Harvesting (RWH)

Groundwater extraction is rampant in many developing countries and urban areas whereas the natural recharge is decreasing due to covering of Earth's surface for various developmental activities. This leads to declining levels of groundwater and deterioration in groundwater quality. Artificial recharge with rain water harvesting techniques offers an excellent scope to arrest this degradation. This paper presents a study that analyzes the influence of rain water harvesting (RWH) on groundwater storage and quality. Chennai City, India is selected as study area, as major RWH implementation has taken place during 2002–2003 due to Government legislation. Preliminary analysis of groundwater levels were done spatially and temporally. Groundwater table contours were drawn using the GIS software for pre‐ (1999–2000) and post‐RWH (2009–2010) periods. The groundwater levels follow a decreasing trend before implementation of RWH where as a positive increasing trend takes place after construction of RWH structures. “Groundwater Estimation Committee (GEC)” norms of Government of India were used to estimate the change in storage during pre‐ and post‐RWH periods, which are found to be 1.76 × 10⁶ and 32.77 × 10⁶ m³, respectively. The results show that the implementation of RWH has increased the groundwater storage considerably. Also, the influence of RWH on groundwater quality is found to be encouraging in some parts of the studied area.     

Efficient management of e-wastes

Electricals and electronic equipments that have reached its utilization period are disposed by the consumer are considered as e-waste. The categories of e-waste range from household appliances to machines used in offices and consumer goods. The rise in problem is due to scarcity of proper place for disposing the e-wastes. Hence, the wastes are disposed in open landfills by the consumers which lead to direct reaction of the e-waste with the environment. The release of harmful toxins and chemicals by the e-wastes causes hazardous effects on living beings. Several processes are introduced in recycling and recovering the harmful metals present in the electronic equipments. The most important reasons for e-waste recycling are waste removal as well as recovery of valuable materials present in the waste. Developed countries such as USA and UK follow some strict rules and regulations about managing the increasing amount of e-wastes, whereas India still needs to have a rigid law for the e-waste management. Prior recycling and recovering the important metals from electronic wastes, it is crucial to ascertain the amount of the metal present in the e-waste. Plastics followed by metals are the main components found in electronic wastes. Hazardous metals such as copper, lead and cadmium are predominant in almost all kinds of e-wastes. Determination of the components present in the electronic wastes guides for the proper path to be followed for recovering the components from the wastes. The review deals with status of e-waste across the world and methods of recovery and management.     

Water Content Ratio: An Effective Substitute for Liquidity Index for Prediction of Shear Strength of Clays

Undrained shear strength of saturated clays is a very important property in geo-technical engineering practice. Since the collection of undisturbed samples and testing the same is difficult task and time consuming process, any attempt to obtain correlations between shear strength and consistency limits would be highly desirable. Several attempts have been made in the past to correlate shear strength with Liquidity index. The computation of Liquidity index involves the value of plastic limit determined by Casagrande thread rolling method; but the determination of the same is relatively a difficult task in geotechnical engineering practice especially so in less plastic soils. It has been shown that a good linear correlation exists between log of shear strength and water content ratio (ratio of water content to liquid limit). With the help of numerous experimental results, it could be established that water content ratio could replace the well-known parameter liquidity index to predict shear strength. This enables to eliminate the determination of the plastic limit. The relation between water content ratio and liquidity index depends on the liquid limit to plastic limit ratio, irrespective of the geological origin of the soil.     

High energy X-γ ray spectrometer on the Chandrayaan-1 mission to the Moon

The Chandrayaan-1 mission to the Moon scheduled for launch in late 2007 will include a high energy X-ray spectrometer (HEX) for detection of naturally occurring emissions from the lunar surface due to radioactive decay of the²³⁸U and²³²Th series nuclides in the energy region 20–250 keV. The primary science objective is to study the transport of volatiles on the lunar surface by detection of the 46.5 keV line from radioactive²¹⁰Pb, a decay product of the gaseous²²²Rn, both of which are members of the²³⁸U decay series. Mapping of U and Th concentration over the lunar surface, particularly in the polar and U-Th rich regions will also be attempted through detection of prominent lines from the U and Th decay series in the above energy range. The low signal strengths of these emissions require a detector with high sensitivity and good energy resolution. Pixelated Cadmium-Zinc-Telluride (CZT) array detectors having these characteristics will be used in this experiment. Here we describe the science considerations that led to this experiment, anticipated flux and background (lunar continuum), the choice of detectors, the proposed payload configuration and plans for its realization     

Tsunami in the last 15 years: a bibliometric analysis with a detailed overview and future directions

In the last fifteen years, tsunami science has progressed at a rapid pace. Three major tsunamis: The Indian Ocean in 2004, the 2011 Tohoku tsunami, and the 2018 Palu tsunami were significant landmarks in the history of tsunami science. All the three tsunamis, as mentioned, suffered from either no warning or poor reception of the alerts issued. Various lessons learned, consequent numerical models proposed, post-2004 tsunami damage findings manifested into solutions. However, the misperceived solutions led to a disastrous impact of the 2011 Tohoku event. In the following years, numerous improvements in warning systems and community preparedness frameworks were proposed and implemented. The contributions and new findings have added multi-fold advancements to tsunami science progress. Later, the 2018 Palu tsunami happened and again led to a massive loss of life and property. The warning systems and community seemed un-prepared for this non-seismic tsunami. A significant change is to take place in tsunami science practices and solutions. The 2018 tsunami is one of the most discussed and researched events concerning the palaeotsunami records, damage assessment, and source findings. In the new era, using machine learning and deep learning prevails in all the fields related to tsunami science. This article presents a complete 15-year bibliometric analysis of tsunami research from Scopus and Web of Science (WoS). The review of majorly cited documents in the form of a progressing storyline has highlighted the need for multidisciplinary research to design and propose practical solutions.