Shock induced vaporization of anhydrite CaSO4 and calcite CaCO3

Discovery of abundant anhydrite (CaSO4) and gypsum (CaSO4.2H2O) in the otherwise carbonate sediments comprising the upper portion of the rocks contained within the Chicxulub impact crater has prompted research on the shock-induced vaporization of these minerals. We use a vaporization criterion determined by shock-induced entropy. We reanalyze the shock wave experiments of Yang [1]. He shocked 30% porous anhydrite and 46% porous calcite. Post-shock adiabatic expansion of the sample across a 5 mm-thick gap and then impact upon an aluminum witness plate backed by LiF window that is monitored with a VISAR. Reanalysis uses Herrman's P-alpha model [2] for porous materials, and a realistic interpolation gas equation-of-state for vaporization products. Derived values of the entropies for incipient and complete vaporization for anhydrite are 1.65±0.12 and 3.17±0.12 kJ(kg.K)–1, and for calcite these are 0.99±0.11 and 1.93±0.11 kJ(kg.K)–1. Corresponding pressures for incipient and complete vaporization along the Hugoniot of non-porous anhydrite are 32.5±2.5 and 122±13 GPa and for non-porous calcite are 17.8±2.9 and 54.1±5.3 GPa, respectively. These pressures are a factor of 2–3 lower than reported earlier by Yang

Aging in the Shadow of COVID-19

The coronavirus disease 2019 (COVID-19) pandemic presents a major challenge to societies all over the world. This new virus threat both socially as well as economically regarding health and safety of human being irrespective of age, race or social status across the world. This expository paper focuses on impact of COVID-19 upon elderly and importance of social distancing and isolation for elderly people. This paper also explores the scenario of COVID-19 in India and the measures that government bodies are taking to contain and mitigate it. Role and responsibilities of families and caregivers to keep away the elderly disease-free, spirited and mentally fit. Those in isolation or quarantine need special care: telephonic counselling, digital contact with family and ensuring adequate nutrition is vital. The study is primarily based on secondary data including books, journals, newspapers, and other governmental reports.  

Shock temperatures in calcite (CaCO3): Implication for shock induced decomposition

The temperatures induced in crystalline calcite upon planar shock compression (95–160 GPa) are reported from two-stage light gas-gun experiments. The temperatures are obtained fitting 6-channel optical pyrometer radiances in the 450 to 900 nm range, to a Planck radiation law temperature varied from 3300 to 5400 K. Calculations demonstrate that the temperatures are some 400 to 1350 K lower than if either shock-induced melting and/or disproportionation of calcite behind the shock front was not occurring. Here calcite is modeled as disproportionating into a molecular liquid, or a solid CaO plus CO2 gas. For temperature calculations, specific heat at constant volume for one mole of CO2 is taken to be 6.7R as compared to 9R in the solid state; whereas calcite and CaO have their solid state values (15R and 6R). Calculations also suggest that the onset of decomposition in calcite to CaO and CO2 during loading occurs at ~75±10 GPa, along the Hugoniot whereas decomposition begins upon unloading from 18 GPa. The 18 GPa value is based on comparison of VISAR measurements of particle velocity profiles induced upon isentropic expansion with one-dimensional numerical simulation

Induction of flowering in Lemna paucicostata, a short-day plant, by chelating agents and iron

Lemna paucicostata is a short-day plant which normally flowers only in a medium supplemented with EDTA or EDDHA. On a molar basis EDDHA is more effective for induction of flowering. The chelating agent can be replaced by high concentrations of ferric citrate in the medium. Simultaneous supply of both EDDHA and a high level of ferric citrate results in flowering even under long days

Melamine Polyimide Composite Fire Resistant Intumescent Coatings

Components of intumescent coatings acid source, carbon source and blowing agent like melamine linked together by a binder provide cumulative fire retardant properties. When temperature of the coating surface reaches a critical temperature under the heat of flame, the surface begins to melt and is converted into highly viscous liquid. Simultaneously, reactions are initiated that result in the release of inert gases with low thermal conductivity. These gases are trapped inside the viscous fluid forming insulating char. The special composite of melamine polyimide, a C source and melamine a blowing agent showed high performance heat resistance in the present study. Polyimides have excellent heat and chemical resistance, excellent adhesion to a number of substrates and superior mechanical properties, such as high flexural modulus and compressive strength. Polyimides are also known to possess outstanding dimensional stability under loads, which allows their use in high temperature environments. Effect of the monomer on chemical reactivity between the binder and the intumescent additives has been studied by thermo-gravimetric analysis, differential scanning calorimeter and FTIR analysis. Thermal insulation studies by various intumescent composite coatings, applied on aluminium plates provided useful time temperature profiles.Defence Science Journal, 2013, 63(4), pp.442-446, DOI:http://dx.doi.org/10.14429/dsj.63.487

Environmental orientation and ecotourism awareness among pilgrims, adventure tourists, and leisure tourists

For the sustainable development of tourism in destination areas, it is important to have responsible visitors with high pro-environmental orientation and a critical minimum knowledge of ecotourism. Most of the pilgrimage, adventurous, and leisure destinations of India are in ecologically sensitive locations with bountiful environmental resources. Thus, understanding tourists’ environmental orientation is critical for destination management. In this context, the present study investigates the environmental orientation and ecotourism awareness of tourists visiting some of the key environmental hotspots of northern India. A comparative analysis of the environmental orientations of pilgrims, adventurists, and leisure tourists is also carried out. The findings generally reveal that there exist significant differences among these categories in terms of environmental orientation and awareness about ecotourism. Pilgrims and adventurists exhibit superior environmental orientation compared to leisure tourists. Yet, when it comes to the awareness of ecotourism, none of the groups under study show great awareness, except that adventurists stand better compared to the other two groups

An Improved Algorithm for Faster Multi Keyword Search in Structured Organization

Searching is the major concern in the database operation. For accessing the information from database it is always required to perform the search. If the search process is efficient then time taken the get the required information will also be less. In this scenario, contain the information organized in the structured data for the big organization like any automobile industry maintaining information regarding its department. Now if perform the keyword based query, then on based of the keyword the queries will be formed. So, in order to reduce the time involved in the formation of the queries from the table have suggested the use of the associative mapping table in the search mechanism which will reduce the time involved in the process. The main aim this work is save the CPU time and efficient utilization of CPU to solve the purpose of the green computing

Mass spectrometer calibration of Cosmic Dust Analyzer

The time of flight mass spectrometer of the Cosmic Dust Analyzer (CDA) instrument aboard the Cassini spacecraft, is expected to be placed in orbit about Saturn to sample the ring material and satellite impact ejecta. Upon impact of an incident dust particle against the target plate at velocities of 5-100 km/s, some 10–8 to 10–5 times the particle mass of positive valence, single-charged ions is induced. These are analyzed via a time-of-flight mass spectrometer. Initial experiments employing a pulsed N2 laser (>300 µJ/pulse, 4ns, 337nm) acting on a suite of samples are described. The laser beam is focussed to deliver the light pulses onto a laser power density (1011 W/cm2) to simulate the impact of particles. Laser ionization produced a charge of 4.6 pC per pulse for aluminum alloy. Estimating that each Al+1 ion require energy of 5.98 eV ionization energy/ion implies that 10–5% of the laser energy produced ions and the present system has a 5% efficiency of collecting the laser-irradiation induced ions. Employing a multi-channel plate detector in this mass spectrometer yields for Al-Mg-Cu alloy and kamacite (Fe-Ni mineral) targets well defined peaks at 24 (Mg+1), 27 (Al+1) and 64 (Cu+1), and 56 (Fe+1), 58 (Ni+1) and 60 (Ni+1) dalton, respectively

Lens thickness and associated ocular biometric factors among cataract patients in tertiary hospital

Background: A significant factor in determining intraocular lens power is the biometry assessment of cataract patients prior to surgery. To evaluate the distribution of lens thickness (LT) and its associations with other ocular biometric factors among cataract patients. Methods: Total 978 eyes from cataract patients were retrospectively included. Ocular biometric factors including k1, k2, LT, central corneal thickness (CCT), anterior chamber depth (ACD), white-to-white (WTW) distance, and axial length (AL) were collected based on the medical records. The associations between LT and general or ocular factors were assessed. We analyzed the data using descriptive analysis and correlated each variable using the Spearman’s Rho analysis. Results: The mean age was 62.5±15.70 years and 55.11% were females. Mean LT was 4.35±0.41 mm. The LT was greater in older patients. LT positively correlated with AL, WTW and CCT, while negatively correlated with ACD. Conclusions: LT is an important biometric parameter that should be considered, along with other biometric parameters, in determining effective lens position in patients undergoing cataract surgery. ACD is predominantly influenced by LT than the AL

Study of noise effect on bearing vibration signal based on statistical parameters

The signals emanating from the bearings are complex and contribute to various distributions. The effect of the distribution and mathematical operations are responsible for the change in the statistical moments. This paper investigates the effect of noise on statistical moments of the bearing vibration signals. Initially, the distribution function for Healthy, inner race defect (IRD), outer race defect (ORD), and ball defect (BD) are tested using Kolmogorov Smirnov test (K-S test). The resulting distributions obtained from the K-S test are normal and Laplacian distributed patterns and convey the faulty state of the bearings. The change in noise levels and their influence on the statistical moments are verified. It is observed, the kurtosis for IRD and ORD decreases with increase in noise, whereas, the trend increases for healthy and BD faults