212 research outputs found
Stochastic modeling and visualization of a tortilla chip
No full textDue to the character of the original source materials and the nature of batch digitization, quality control issues may be present in this document. Please report any quality issues you encounter to [email protected], referencing the URI of the item.Includes bibliographical references (leaves 146-148).Issued also on microfiche from Lange Micrographics.Monte Carlo simulation was used as an alternative technique and stochastically modeled component distribution in a tortilla chip. The components included oil, water, gas and solids. A conditional percolation approach was used to model pore size distribution and predict thermal conductivity in a tortilla chip fried at 190���C for 60 seconds. The results were simulated using Ensight[TM] (CEI, Morrisville, NC), a scientist's plotting tool. The individual components were considered as scalars on a three-dimensional mesh and isosurfaces were plotted across them. Isosurfaces are surfaces that follow a constant value of a variable through three-dimensional elements. Isosurfaces are to three-dimensional elements what contour lines are to two-dimensional elements. The component clusters were counted and their mean size determined. The clusters were further analyzed for different frying conditions. Similar models were constructed for freeze-dried and steam-baked tortilla chips. The model predicted maximum oil absorption in a control tortilla chip (once baked) during the first 10 seconds of frying. Simultaneously, maximum water evaporation was observed during the first 10 seconds of frying. Maximum pore expansion occurred between 30 and 40 seconds of frying. Steam baking the tortilla chip gelatinization. This surface prevented water evaporation as well as oil absorption. The moisture provided for an increasing porosity in the product (47.12% to 54.04%). The freeze-dried tortilla chip had higher internal oil content due to smaller pores spread over the matrix. The smaller pores are due to the absence of a tight barrier along the tortilla's surface, as freeze-drying does not cause starch gelatinization (no heat treatment prior to frying). The pore volume distribution in a control tortilla chip cannot be modeled effectively using the percolation approach, because pore interconnectivity increases considerably above a threshold percolation volume (p[]) (between 34.5% and 46.80%). Thermal conductivity in a control (once baked) tortilla chip was modeled effectively using the percolation approach. The product was assumed to be a three-component mixture, the components being air, oil, and solids bound by water. The average thermal conductivity for a frying time of 60 seconds and a frying temperature of 190���C was 0.17 W/m���C
Which degrees of freedom play a role in multinucleon transfer processes?
No full textA presentation of some recent significant results obtained in the field of multinucleon transfer reactions at Coulomb barrier energies is given. The comparison of the experimental observables with the predictions of theoretical models treating quasi-elastic and deep-inelastic processes on the same ground reveals interesting features of the reaction mechanisms not clearly identified in the past
The focal plane detector of the magnetic spectrometer PRISMA
No full textThe characteristics and performance of the focal plane detector system developed for the magnetic spectrometer PRISMA are presented. It is composed of a multi-wire parallel plate avalanche counter (providing X, Y and riming signals) followed by a multi-parametric transverse field ionization chamber array (providing multiple Delta E signals). The detector array has been built to match the very large acceptance of PRISMA and provides optimal performance in the complete identification (nuclear charge, energy and mass) of nuclei produced in heavy-ion binary reactions
Synthesis, Structural Characterization of Substituted Phenoxyimine Based Ti(IV) Complexes for Ring Opening Polymerization and DFT Studies
No full textAbstract A series of 4 new titanium complexes bearing phenoxyimine ligands that differ in their steric and electronic properties have been synthesized and investigated for the polymerization of ethylene and rac‐lactide. X‐ray crystal structures of these catalysts reveal compounds 1–3 exhibit distorted octahedral geometry while complex 4 shows distorted trigonal bipyramidal. The substituents on the phenoxyimine framework have a profound influence on the catalytic activities of these compounds in the polymerization reactions. All four complexes afforded polylactide with a heterotactic bias in ring opening polymerization of rac‐lactide. In addition to this, density functional theory calculations using (B3LYP) with the 6‐311++G (d, p) basis set and no constraints were used while doing geometry optimizations and compared with experimental results. Hirshfeld surface analysis, MEP and Mulliken charge also reported an unexpected relationship between the nitrogen, oxygen on the ligands, titanium isopropoxide, and good relation between the experimental findings.Funder:
Nara Institute of Science and Technology
https://doi.org/10.13039/10001532
Population of nuclei far from stability via multinucleon transfer: the 58Ni+208Pb case
No full textMultinucleon transfer reactions in Ni-58 + Pb-208 were studied at E-LAB = 328.4 MeV. Light products were identified with a time-of-flight magnetic spectrometer and heavy fragments with a multiwire parallel plate detector. From the kinematic coincidence the survival probability of the heavy fragments against fission was derived. Data are compared with semiclassical model calculations
Study of nucleon correlations effects via multinucleon transfer in 40Ca+208Pb
No full textMultinucleon transfer reactions in 40Ca+208Pb have been studied at several bombarding energies close to the Coulomb barrier. Light reaction products have been identified in mass and charge with a time-of-flight spectrometer. The energy spectra of the inclusive two neutron pick-up channel show a population in a narrow region of excitation energies which corresponds to the predicted energy of pairing-vibration state in 42Ca
Investigation on the physicochemical properties of Ce0.8Eu0.1M0.1O2−δ (M = Zr, Hf, La, and Sm) solid solutions towards soot combustion
No full textThis investigation focuses on the manipulation of the physicochemical properties and oxygen defect concentration of europium doped CeO2 by the introduction of a second dopant (co-dopant, M). Accordingly, in this study a series of Ce0.8Eu0.1M0.1O2-delta (M = Zr, Hf, La, and Sm) nano-oxides were prepared and tested for diesel soot oxidation catalysis. The systematic characterization studies indicated successful incorporation of both dopants in the cubic fluorite crystal structure of CeO2. A remarkable enhancement in the reduction properties and oxygen defect concentration was observed for the co-doped samples from structural and chemical analyses. The aliovalent co-doped materials exhibited better performance than the isovalent co-doped materials. The catalytic activity order of the prepared materials towards model soot oxidation was Ce0.8Eu0.1La0.1O2-delta > Ce0.8Eu0.1Sm0.1O2-delta > Ce0.8Eu0.1Hf0.1O2-delta > Ce0.8Eu0.1Zr0.1O2-delta > Ce0.9Eu0.1O2-delta > CeO2. The most favorable modification of the physicochemical properties of europium doped ceria was ascertained in the presence of La as a co-dopant compared to other combinations investigated. The correlation of the physicochemical properties with the catalytic activity has also been clearly demonstrated in the manuscript
Structural and optical modification of ZnO:Al thin films by molybdenum co-doping and the origin of green emission
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