Simulation of mesoscale structure of thunderstorm using ARPS Model

In this paper mesoscale structures of two thunderstorm events over Delhi have been simulated using ARPS (Advanced Regional Prediction System) model. Numerical experiments were carried out using radiosonde data of Delhi and applying a potential temperature perturbation for triggering convective activity. The simulation exercise demonstrates strong updrafts and downdrafts associated with the thunderstorm cells, indicating the presence of very strong localized convection. The development and evolution of thunderstorm and propagation of associated precipitation zone are clearly brought out in this simulation study.

Phase Formation during Heating of Amorphous Nickel-Based BNi-3 for Joining of Dissimilar Cobalt-Based Superalloys

Phase transformations and the melting range of the interlayer BNi-3 were investigated by differential scanning calorimetry, which showed three stages of crystallization during heating. There were three exothermic peaks that indicated crystallization in the solid state. The cobalt-based X-45 and FSX-414 superalloys were bonded with interlayer BNi-3 at a constant holding time of 10 min with bonding temperatures of 1010, 1050, 1100, and 1150 °C using a vacuum diffusion brazing process. Examination of microstructural changes in the base metals with light microscopy and scanning electron microscopy coupled with X-ray spectroscopy based on the energy distribution showed that increasing temperature caused a solidification mode, such that the bonding centerline at 1010 °C/10 min included a γ-solid solution, Ni3B, Ni6Si2B, and Ni3Si. The athermally solidified zone of the transient liquid phase (TLP)-bonded sample at 1050 °C/10 min involved a γ-solid solution, Ni3B, CrB, Ni6Si2B, and Ni3Si. Finally, isothermal solidification was completed within 10 min at 1150 °C. The diffusion-affected zones on both sides had three distinct zones: a coarse block precipitation zone, a fine and needle-like mixed-precipitation zone, and a needle-like precipitation zone. By increasing the bonding temperature, the diffusion-affected zone became wider and led to dissolution.

Response of Monsoon Rainfall to Changes in the Latitude of the Equatorward Coastline of a Zonally Symmetric Continent

Recent studies have shown that the rapid onset of the monsoon can be interpreted as a switch in the tropical circulation, which can occur even in the absence of land–sea contrast, from a dynamical regime controlled by eddy momentum fluxes to a monsoon regime more directly controlled by energetic constraints. Here we investigate how one aspect of continental geometry, that is, the position of the equatorward coastal boundary, influences such transitions. Experiments are conducted with an aquaplanet model with a slab ocean, in which different zonally symmetric continents are prescribed in the Northern Hemisphere poleward from southern boundaries at various latitudes, with “land” having a mixed layer depth two orders of magnitude smaller than ocean. For continents extending to tropical latitudes, the simulated monsoon features a rapid migration of the convergence zone over the continent, similar to what is seen in observed monsoons. For continents with more poleward southern boundaries, the main precipitation zone remains over the ocean, moving gradually into the summer hemisphere. We show that the absence of land at tropical latitudes prevents the rapid displacement into the subtropics of the maximum in lower-level moist static energy and, with it, the establishment of an overturning circulation with a subtropical convergence zone that can transition rapidly into an angular momentum–conserving monsoon regime.

Evolution of Interfacial Features of MnO-SiO2 Type Inclusions/Steel Matrix during Isothermal Heating at Low Temperatures

To clarify the evolution of interfacial features between MnO-SiO2 type inclusions and Si-Mn killed steel during isothermal heating at low temperatures, two diffusion couple samples were investigated under heat treatment at 1173 K and 1273 K, respectively. The experimental results show that the diffusion of oxygen from the oxide to the alloy is the restrictive link of the solid-state reaction between MnO-SiO2-FeO oxide and steel matrix at low heating temperatures. With increasing heating time or temperature, more FeO in the oxide decomposed, and the resulting oxygen diffused into the alloy and reacted with Mn and Si elements. The critical heating temperature at which the interfacial reaction can occur was determined to be 1173 K. And a dynamic model that predicts the change in the width of the particles precipitation zone at low temperatures was also established based on Wagner equation.

Cholesterol Assimilation of Saccharomyces cerevisiae B-18 isolated from gastrointestinal tract of Javanese duck

This study had a purpose of obtaining potential indigenous yeasts for assimilating cholesterol and assessed the in vitro activity of Bile Salt Hydrolase (BSH) using Chloramphenicol Yeast Glucose (CYG) media supplemented CaCl2 and Taurodeoxycholic Acid (TDCA). Yeasts were collected from the gastrointestinal tract of Indonesian native chicken (Gallus javanicus), Javanese duck (Anas javanicus), and Muscovy duck (Anas moschata). The BSH assay was performed to determine secretion of BSH from yeast strain to conjugate bile salts into cholic acid-free by measuring precipitation zone in a specific medium. The quantitative measurement to assimilate cholesterol in yeast using CYG broth contained soluble cholesterol (500 ppm) and incubated at 30°C for 72 hours. Microplate reader used to analyze cholesterol content in the supernatant. Data were analyzed using Analysis of Variance (ANOVA) with one way completely randomized. Precipitation zone found among isolates did not significantly different (P>0.05). Isolate B-18 from Javanese duck performed the highest percentage of assimilating cholesterol with the value of 51.83% and identified as S. cerevisiae. This isolate was closely related to S. cerevisiae mt 21s (accession number X00149.1)based on phylogenetic tree analysis. It could be concluded that S. cerevisiae B-18was potential for assimilating cholesterol in vitro.

Diurnal Cycle of Precipitation Observed in the Western Coastal Area of Sumatra Island: Offshore Preconditioning by Gravity Waves

This study analyzes data obtained by intensive observation during a pilot field campaign of the Years of the Maritime Continent Project (Pre-YMC) to investigate the diurnal cycle of precipitation in the western coastal area of Sumatra Island. The diurnal cycle during the campaign period (November–December 2015) is found to have a number of similarities with statistical behavior of the diurnal cycle as revealed by previous studies, such as afternoon precipitation over land, nighttime offshore migration of the precipitation zone, and dependency on Madden–Julian oscillation (MJO) phase. Composite analyses of radiosonde soundings from the Research Vessel (R/V) Mirai, deployed about 50 km off the coast, demonstrate that the lower free troposphere starts cooling in late afternoon (a couple of hours earlier than the cooling in the boundary layer), making the lower troposphere more unstable just before precipitation starts to increase. As the nighttime offshore precipitation tends to be more vigorous on days when the cooling in the lower free troposphere is larger, it is possible that the destabilization due to the cooling contributes to the offshore migration of the precipitation zone via enhancement of convective activity. Comparison of potential temperature and water vapor mixing ratio tendencies suggests that this cooling is substantially due to vertical advection by an ascent motion, which is possibly a component of shallow gravity waves. These results support the idea that gravity waves emanating from convective systems over land play a significant role in the offshore migration of the precipitation zone.

Sensitivity of Rhizoctonia Isolates to Phenazine-1-Carboxylic Acid and Biological Control by Phenazine-Producing Pseudomonas spp.

Rhizoctonia solani anastomosis groups (AG)-8 and AG-2-1 and R. oryzae are ubiquitous in cereal-based cropping systems of the Columbia Plateau of the Inland Pacific Northwest and commonly infect wheat. AG-8 and R. oryzae, causal agents of Rhizoctonia root rot and bare patch, are most commonly found in fields in the low-precipitation zone, whereas R. solani AG-2-1 is much less virulent on wheat and is distributed in fields throughout the low-, intermediate-, and high-precipitation zones. Fluorescent Pseudomonas spp. that produce the antibiotic phenazine-1-carboxylic acid (PCA) also are abundant in the rhizosphere of crops grown in the low-precipitation zone but their broader geographic distribution and effect on populations of Rhizoctonia is unknown. To address these questions, we surveyed the distribution of PCA producers (Phz+) in 59 fields in cereal-based cropping systems throughout the Columbia Plateau. Phz+ Pseudomonas spp. were detected in 37 of 59 samples and comprised from 0 to 12.5% of the total culturable heterotrophic aerobic rhizosphere bacteria. The frequency with which individual plants were colonized by Phz+ pseudomonads ranged from 0 to 100%. High and moderate colonization frequencies of Phz+ pseudomonads were associated with roots from fields located in the driest areas whereas only moderate and low colonization frequencies were associated with crops where higher annual precipitation occurs. Thus, the geographic distribution of Phz+ pseudomonads overlaps closely with the distribution of R. solani AG-8 but not with that of R. oryzae or R. solani AG-2-1. Moreover, linear regression analysis demonstrated a highly significant inverse relationship between annual precipitation and the frequency of rhizospheres colonized by Phz+ pseudomonads. Phz+ pseudomonads representative of the four major indigenous species (P. aridus, P. cerealis, P. orientalis, and P. synxantha) suppressed Rhizoctonia root rot of wheat when applied as seed treatments. In vitro, mean 50% effective dose values for isolates of AG-8 and AG-2-1 from fields with high and low frequencies of phenazine producers did not differ significantly, nor was there a correlation between virulence of an isolate and sensitivity to PCA, resulting in rejection of the hypothesis that tolerance in Rhizoctonia spp. to PCA develops in nature upon exposure to Phz+ pseudomonads.