Further Studies of Unusual Fission Mass Distributions using 190 MeV Protons

This research was sponsored by the National Science Foundation Grant NSF PHy 87-1440

Investigation of Within-Tablet Dynamics for Extended Release of a Poorly Soluble Basic Drug from Hydrophilic Matrix Tablets Using ATR-FTIR Imaging

© 2020 American Chemical Society. Hydrophilic matrices are an effective option for oral controlled release but can face challenges in terms of bioavailability and efficacy when used in conjunction with poorly soluble, weakly basic drugs. Attenuated total reflectance Fourier transform infrared (ATR-FTIR) imaging provides dynamic information relating to the location and chemical nature of both the sustained release matrix and the active pharmaceutical ingredient (API) during hydration/dissolution. In this study, we have identified a model system combining itraconazole (IT), a poorly soluble, weakly basic API that has pKa in the physiological range, and hydroxypropyl methylcellulose, which is a commonly used oral tablet matrix. This system was investigated to determine the swelling kinetics at different pH values at a fixed ionic strength and to facilitate the study of the influence of hydrating media pH on the drug particle movement (translocation). Using ATR-FTIR imaging, we were able to show that gel layer formation and swelling were independent of pH but highly dependent on the ionic strength of the hydrating medium in placebo tablets. When the ionic strength was fixed, gel layer formation and radial swelling were both shown to be pH-dependent when IT was incorporated into the matrix. This was verified using optical imaging. The chemical specificity of ATR-FTIR imaging permitted the observation of transformational changes of IT from the free base to the ionized form in the tablet core during hydration. This phenomenon was shown to be greater at pH 1.5 than at pH 7. ATR-FTIR imaging was able to follow drug particle translocation at both pH 1.5 and pH 7; however, the extent of migration away from the tablet core was shown to be greater at lower pH. The location of the translocated particles within the gel layer was different between the two studied pH values, with particles being located close to the swelling front at pH 7 and within the diffusion front at pH 1.5. In both pH environments, the translocated IT particles were shown to be predominantly in the free base form. No evidence of fully solubilized IT was observed in the surrounding medium because of the inherent aqueous solubility of IT being below the instrument detection limits. This work highlighted the value of utilizing a chemically specific spectroscopic tool to increase the understanding of the nature of the factors affecting the release of a pH-dependent, poorly soluble drug from a hydrophilic matrix at different pH values and permitted greater insights into what happens inside the polymer matrix during drug release

Non-perturbative Propagators, Running Coupling and Dynamical Quark Mass of Landau gauge QCD

The coupled system of renormalized Dyson-Schwinger equations for the quark, gluon and ghost propagators of Landau gauge QCD is solved within truncation schemes. These employ bare as well as non-perturbative ansaetze for the vertices such that the running coupling as well as the quark mass function are independent of the renormalization point. The one-loop anomalous dimensions of all propagators are reproduced. Dynamical chiral symmetry breaking is found, the dynamically generated quark mass agrees well with phenomenological values and corresponding results from lattice calculations. The effects of unquenching the system are small. In particular the infrared behavior of the ghost and gluon dressing functions found in previous studies is almost unchanged as long as the number of light flavors is smaller than four.Comment: 34 pages, 10 figures, version to be published by Phys. Rev.

Acceptance and Use of E-Learning Based on Cloud Computing: The Role of Consumer Innovativeness

Cloud computing and E-learning are the inevitable trend of computational science in general, and information systems and technologies in specific.However, there are not many studies on the adoption of cloud-based E-learning systems. Moreover, while there are many papers on information system adoption as well as customer innovativeness, the innovativeness and adoption in the same model seems to be rare in the literature. The study combines the extended Unified Theory of Acceptance and Use of Technology (UTAUT2) and consumer innovativeness on the adoption of E-learning systems based on cloud computing. A survey was conducted among 282 cloud-based E-learning participants and analyzed by structural equation modeling (SEM). The findings indicate that the adoption of cloud-based E-learning is influenced by performance expectancy, social influence, hedonic motivation, and habit. Interestingly, although innovativeness is not significant to use intention, it has a positive effect on E-learning usage which is relatively new in Vietnam

Method to compute the stress-energy tensor for the massless spin 1/2 field in a general static spherically symmetric spacetime

A method for computing the stress-energy tensor for the quantized, massless, spin 1/2 field in a general static spherically symmetric spacetime is presented. The field can be in a zero temperature state or a non-zero temperature thermal state. An expression for the full renormalized stress-energy tensor is derived. It consists of a sum of two tensors both of which are conserved. One tensor is written in terms of the modes of the quantized field and has zero trace. In most cases it must be computed numerically. The other tensor does not explicitly depend on the modes and has a trace equal to the trace anomaly. It can be used as an analytic approximation for the stress-energy tensor and is equivalent to other approximations that have been made for the stress-energy tensor of the massless spin 1/2 field in static spherically symmetric spacetimes.Comment: 34 pages, no figure

Experimental evidence for 56Ni-core breaking from the low-spin structure of the N=Z nucleus 58Cu

Low-spin states in the odd-odd N=Z nucleus 58Cu were investigated with the 58Ni(p,n gamma)58Cu fusion evaporation reaction at the FN-tandem accelerator in Cologne. Seventeen low spin states below 3.6 MeV and 17 new transitions were observed. Ten multipole mixing ratios and 17 gamma-branching ratios were determined for the first time. New detailed spectroscopic information on the 2+,2 state, the Isobaric Analogue State (IAS) of the 2+,1,T=1 state of 58Ni, makes 58Cu the heaviest odd-odd N=Z nucleus with known B(E2;2+,T=1 --> 0+,T=1) value. The 4^+ state at 2.751 MeV, observed here for the first time, is identified as the IAS of the 4+,1,T=1 state in 58Ni. The new data are compared to full pf-shell model calculations with the novel GXPF1 residual interaction and to calculations within a pf5/2 configurational space with a residual surface delta interaction. The role of the 56Ni core excitations for the low-spin structure in 58Cu is discussed.Comment: 15 pages, 7 figures, submitted to Phys. Rev.

The New Urban Revival in the United States

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/68657/2/10.1080_00420989320081901.pd

Dark matter in supersymmetric models with axino LSP in Randall-Sundrum II brane model

The axino dark matter hypothesis in RSII brane model is studied. Within the framework of CMSSM we assume that the lightest neutralino or stau is the NLSP, and that the axino production has a single contribution from the NLSP decay. It is found that the axino can play the role of dark matter in the universe and we determine what the axino mass should be for different values of the five-dimensional Planck mass. An upper bound is obtained for the latterComment: 12 pages,3 figures, accepted in JHE

Post-Newtonian SPH calculations of binary neutron star coalescence. II. Binary mass ratio, equation of state, and spin dependence

Using our new Post-Newtonian SPH (smoothed particle hydrodynamics) code, we study the final coalescence and merging of neutron star (NS) binaries. We vary the stiffness of the equation of state (EOS) as well as the initial binary mass ratio and stellar spins. Results are compared to those of Newtonian calculations, with and without the inclusion of the gravitational radiation reaction. We find a much steeper decrease in the gravity wave peak strain and luminosity with decreasing mass ratio than would be predicted by simple point-mass formulae. For NS with softer EOS (which we model as simple $\Gamma=2$ polytropes) we find a stronger gravity wave emission, with a different morphology than for stiffer EOS (modeled as $\Gamma=3$ polytropes as in our previous work). We also calculate the coalescence of NS binaries with an irrotational initial condition, and find that the gravity wave signal is relatively suppressed compared to the synchronized case, but shows a very significant second peak of emission. Mass shedding is also greatly reduced, and occurs via a different mechanism than in the synchronized case. We discuss the implications of our results for gravity wave astronomy with laser interferometers such as LIGO, and for theoretical models of gamma-ray bursts (GRBs) based on NS mergers.Comment: RevTeX, 38 pages, 24 figures, Minor Corrections, to appear in Phys. Rev.