High-performance Earth system modeling with NASA/GSFC’s Land Information System

The Land Information System software (LIS; http://lis.gsfc.nasa.gov/, 2006) has been developed to support high-performance land surface modeling and data assimilation. LIS integrates parallel and distributed computing technologies with modern land surface modeling capabilities, and establishes a framework for easy interchange of subcomponents, such as land surface physics, input/output conventions, and data assimilation routines. The software includes multiple land surface models that can be run as a multi-model ensemble on global or regional domains with horizontal resolutions ranging from 2.5° to 1 km. The software may execute serially or in parallel on various high-performance computing platforms. In addition, the software has well-defined, standard-conforming interfaces and data structures to interface and interoperate with other Earth system models. Developed with the support of an Earth science technology office (ESTO) computational technologies project round~3 cooperative agreement, LIS has helped advance NASA’s Earth–Sun division’s software engineering principles and practices, while promoting portability, interoperability, and scalability for Earth system modeling. LIS was selected as a co-winner of NASA’s 2005 software of the year award.     

Transport hindrances with electrodialytic recovery of citric acid from solution of strong electrolytes

Electrodialytic(ED) recovery of citric acid(CA) in the presence/absence of strong electrolytes(NaCl, CaCl_2 and FeCl_3) was separately analyzed under different process conditions. Recovery effectiveness was quantitatively estimated from current efficiency values. Efficiency attained optimum value with both flow rate and potential applied, while a monotonic rise was noted with temperature which got lowered beyond 0.1 mol·L~(-1) feed concentration. 40% drop in efficiency was recorded in the presence of strong electrolytes(NaCl, CaCl_2 and FeCl3) in feed relative to their presence in concentrate. Severe transport hindrance and efficiency loss were attributed to adsorption and allied physicochemical changes occurred with anion/cation exchange membranes(AEM/CEM) and these were confirmed through contact angle/Chronopotentiometry/AFM/EDX. Sluggish potential rise(Galvanostatic mode) in Chronopotentiometric analysis indicated diffusion limiting transport of organic acids influenced AEM resistance. XRD and EDX analysis indicated the presence of salt hydrates/ions(Ca~(2+)/Fe~(3+)) over CEM justifying the resistance buildup due to adsorption of multivalent metal ion(s) and salts.     

Estimation of Nusselt number and effectiveness of double‐pipe heat exchanger with Al2O3–, CuO–, TiO2–, and ZnO–water based nanofluids

This paper deals with experimental studies carried out to analyze heat transfer characteristics of Al₂O₃–, CuO–, TiO₂–, and ZnO–water based nanofluids in a double‐pipe, counter flow heat exchanger for different volume concentrations (0.025%, 0.05%, 0.075%, and 0.1%) of the nanofluids. The fabricated double‐pipe heat exchanger is made up of two different materials, viz., copper as the inner tube and unplasticized polyvinyl chloride as the outer tube. The density, viscosity, and thermal conductivity were calculated, and were used to estimate dimensionless numbers, such as Reynolds number, Prandtl number, and Nusselt number, and also to estimate heat exchanger effectiveness. High‐energy ball milling technique was used to prepare nanoparticles and were characterized using X‐ray diffraction, scanning electron microscopy, and transmission electron microscopy. Polyvinyl alcohol (3%) was used as a surfactant for making the nanofluids stable. It was observed from the experiment that with the increase in the volume concentration, thermal conductivity, viscosity, and friction factor increase, whereas the Reynolds number decreases. The experimentally observed data for Nusselt number were formulated into a correlation that matches the data for all these nanofluids within an error of 11.4%. It was found that the highest effectiveness was obtained while using TiO₂–water nanofluids than other nanofluids.     

Chromatin Remodeling in the Brain-a NuRDevelopmental Odyssey

During brain development, the genome must be repeatedly reconfigured in order to facilitate neuronal and glial differentiation. A host of chromatin remodeling complexes facilitates this process. At the genetic level, the non-redundancy of these complexes suggests that neurodevelopment may require a lexicon of remodelers with different specificities and activities. Here, we focus on the nucleosome remodeling and deacetylase (NuRD) complex. We review NuRD biochemistry, genetics, and functions in neural progenitors and neurons.