Synthesis and Characterization of Calcium Hexaboride (CaB6) Nanowires

The objective of the current research was to synthesize calcium hexaboride (CaB6) nanowires for analysis of hydrogen storage materials. Catalyst assisted growth of nanowires under the Vapor-Liquid-Solid synthesis method was performed in a quartz tube furnace. The pyrolysis of diborane (B2H6) gas over calcium oxide (CaO) powders with a thermally coated layer of nickel catalyst was carried out. SEM and TEM analysis have shown the generation of nanowires although calcium and boron did not react in a 1:6 ratio, though 1:4 and 1:8 ratios were achieved. Several types of nanowire compositions were found under EELS and EDX analyses, including calcium and oxygen coated boron nanowires. Overall, it was found that a decrease in the amount of nickel catalyst used is correlated to a decrease in the diameters of the nanowires. A higher diborane gas flow rate into the reaction chamber was also correlated to more abundant nanostructures in the sample

Transmission Infrared Spectroscopy of Ammonia Borane

Transmission infrared spectroscopy can potentially offer unique advantages in studying the mechanisms of hydrogen loss from complex hydrides that are being considered for use as hydrogen storage materials. An apparatus that permits infrared spectra to be obtained over a temperature range of 85 to 1200 K and under either an ambient pressure of selected gases or under vacuum has been designed and its performance characterized. While the method is capable of producing high quality spectra at room temperature and below, several difficulties arise as the sample temperature is increased to the point where hydrogen loss occurs. These challenges include reaction with the host matrix, reaction with residual water or oxygen in the system, and loss of transparency of the sample. The performance of the method is illustrated with spectra obtained for ammonia borane, NH3BH3

Synthesis and Characterization of YB66 Nanowires

The objective of the current research is to synthesize yttrium boride (YB66) nanowires. Catalyst assisted growth of the nanowires under the vapor-liquid-solid (VLS) synthesis method was performed in a quartz tube furnace. The pyrolysis of diborane (B2H6) gas over yttrium oxide (Y2O3) powders with a thermally coated layer of nickel catalyst was carried out. The reaction conditions were at 925o C and a pressure of 390 mTorr with varying reaction times. SEM analysis has shown the growth of nanowires with diameters around 400 nm. A catalyst particle was also seen at the tip of the nanowires, confirming growth by the VLS mechanism. Other analysis techniques that were used include Raman spectroscopy and TEM analysis. The Raman spectra of the nanowires were in good agreement with a Raman spectrum obtained on a YB66 single crystal. However, no other evidence was obtained that the nanowires contained yttrium or that the nanowires consisted of YB66

Characterization of Nickel Assisted Growth of Boron Nanostructures

Boron nanostructures were synthesized by the vapor-liquid-solid mechanism using nickel as a catalyst. Two types of catalyst deposition methods were used: thermal evaporation and solution dispersion of Ni nanopowder. Also, the effect of synthesis temperature on the shapes of the nanostrucrure formed is reported here. The nanostructures were primarily characterized by Scanning Electron Microscopy (SEM). Further qualitative analyses were done with Transmission Electron Microscopy (TEM) and High Resolution Transmission Electron Microscopy (HRTEM). For quantitative analyses Energy Dispersive X-ray spectroscopy (EDX) and Electron Energy Loss Spectroscopy (EELS) were used. These results confirmed that 1) high purity Ni assisted boron nanostructures grow by pyrolysis of diborane, and that 2) oxide assisted growth of the nanostructures did not take place as carbon and oxygen were present only as surface contamination. Selected Area Electron Diffraction (SAED) patterns showed that the nanostructures were mainly crystalline. By decreasing the amount of nickel catalyst that is deposited by thermal evaporation the diameters of the nanowires were reduced. Also, the use of nickel nanopowder as catalyst instead of Ni film resulted in significant reduction in wire diameter. The diameter of the boron nanowires are about 36 nm. With nanowires other types of nanostructures were formed in either type of deposition. At the lower reaction temperature formation of nanosheets was observed

Physics Potential of the ICAL detector at the India-based Neutrino Observatory (INO)

The upcoming 50 kt magnetized iron calorimeter (ICAL) detector at the India-based Neutrino Observatory (INO) is designed to study the atmospheric neutrinos and antineutrinos separately over a wide range of energies and path lengths. The primary focus of this experiment is to explore the Earth matter effects by observing the energy and zenith angle dependence of the atmospheric neutrinos in the multi-GeV range. This study will be crucial to address some of the outstanding issues in neutrino oscillation physics, including the fundamental issue of neutrino mass hierarchy. In this document, we present the physics potential of the detector as obtained from realistic detector simulations. We describe the simulation framework, the neutrino interactions in the detector, and the expected response of the detector to particles traversing it. The ICAL detector can determine the energy and direction of the muons to a high precision, and in addition, its sensitivity to multi-GeV hadrons increases its physics reach substantially. Its charge identification capability, and hence its ability to distinguish neutrinos from antineutrinos, makes it an efficient detector for determining the neutrino mass hierarchy. In this report, we outline the analyses carried out for the determination of neutrino mass hierarchy and precision measurements of atmospheric neutrino mixing parameters at ICAL, and give the expected physics reach of the detector with 10 years of runtime. We also explore the potential of ICAL for probing new physics scenarios like CPT violation and the presence of magnetic monopoles.Comment: 139 pages, Physics White Paper of the ICAL (INO) Collaboration, Contents identical with the version published in Pramana - J. Physic

Metabolic and Transcriptional Modules Independently Diversify Plasma Cell Lifespan and Function

Plasma cell survival and the consequent duration of immunity vary widely with infection or vaccination. Using fluorescent glucose analog uptake, we defined multiple developmentally independent mouse plasma cell populations with varying life- spans. Long-lived plasma cells imported more fluo- rescent glucose analog, expressed higher surface levels of the amino acid transporter CD98, and had more autophagosome mass than did short-lived cells. Low amino acid concentrations triggered re- ductions in both antibody secretion and mitochon- drial respiration, especially by short-lived plasma cells. To explain these observations, we found that glutamine was used for both mitochondrial respira- tion and anaplerotic reactions, yielding glutamate and aspartate for antibody synthesis. Endoplasmic reticulum (ER) stress responses, which link meta- bolism to transcriptional outcomes, were similar between long- and short-lived subsets. Accordingly, population and single-cell transcriptional compari- sons across mouse and human plasma cell subsets revealed few consistent and conserved dif- ferences. Thus, plasma cell antibody secretion and lifespan are primarily defined by non-transcriptional metabolic traits

BacHBerry: BACterial Hosts for production of Bioactive phenolics from bERRY fruits

BACterial Hosts for production of Bioactive phenolics from bERRY fruits (BacHBerry) was a 3-year project funded by the Seventh Framework Programme (FP7) of the European Union that ran between November 2013 and October 2016. The overall aim of the project was to establish a sustainable and economically-feasible strategy for the production of novel high-value phenolic compounds isolated from berry fruits using bacterial platforms. The project aimed at covering all stages of the discovery and pre-commercialization process, including berry collection, screening and characterization of their bioactive components, identification and functional characterization of the corresponding biosynthetic pathways, and construction of Gram-positive bacterial cell factories producing phenolic compounds. Further activities included optimization of polyphenol extraction methods from bacterial cultures, scale-up of production by fermentation up to pilot scale, as well as societal and economic analyses of the processes. This review article summarizes some of the key findings obtained throughout the duration of the project