Surface inspection: Research and development

Surface inspection techniques are used for process learning, quality verification, and postmortem analysis in manufacturing for a spectrum of disciplines. First, trends in surface analysis are summarized for integrated circuits, high density interconnection boards, and magnetic disks, emphasizing on-line applications as opposed to off-line or development techniques. Then, a closer look is taken at microcontamination detection from both a patterned defect and a particulate inspection point of view

Luminescent solar concentrators. 2: Experimental and theoretical analysis of their possible efficiencies

Experimental techniques are developed to determine the applicability of a particular luminescing center for use in a luminescent solar concentrator (LSC). The relevant steady-state characteristics of eighteen common organic laser dyes are given. The relative spectral homogeneity of such dyes are shown to depend upon the surrounding material using narrowband laser excitation. We developed three independent techniques for measuring self-absorption rates; these are time-resolved emission, steady-state polarization anisotropy, and spectral convolution. Preliminary dye degradation and prototype efficiency measurements are included. Finally, we give simple relationships relating the efficiency and gain of an LSC to key spectroscopic parameters of its constituents

Luminescent Solar Concentrators

A type of solar concentrator for photovoltaics utilizing light pipe trapping of luminescence is described. Total collector efficiencies of 3. 2% have been measured, and efficiencies of 10% appear theoretically possible. The photodegradation lifetime of the dyes presently used is about one year under optimal conditions

Identifying global synchronies in marine zooplankton populations: issues and opportunities

Analyses of the influences of climate variability on local zooplankton populations and those within ocean basins are relatively recent (past 5–10 years). What is lacking are comparisons of zooplankton population variability among the world's oceans, in contrast to such global comparisons of fish populations. This article examines the key questions, capabilities, and impediments for global comparisons of zooplankton populations using long-term (>10 year) data sets. The key question is whether global synchronies in zooplankton populations exist. If yes, then (i) to what extent are they driven by “bottom-up” (productivity) or “top-down” (predation) forcing; (ii) are they initiated by persistent forcing or by episodic events whose effects propagate through the system with different time-lags; and (iii) what proportion of the biological variance is caused directly by physical forcing and what proportion might be caused by non-linear instabilities in the biological dynamics (e.g. through trophodynamic links)? The capabilities are improving quickly that will enable global comparisons of zooplankton populations. Several long-term sampling programmes and data sets exist in many ocean basins, and the data are becoming more available. In addition, there has been a major philosophical change recently that now recognizes the value of continuing long-term zooplankton observation programmes. Understanding of life-history characteristics and the ecosystem roles of zooplankton are also improving. A first and critical step in exploring possible synchrony among zooplankton from geographically diverse regions is to recognize the limitations of the various data sets. There exist several impediments that must be surmounted before global comparisons of zooplankton populations can be realized. Methodological issues concerned with the diverse spatial and temporal scales of “monitored” planktonic populations are one example. Other problems include data access issues, structural constraints regarding funding of international comparisons, and lack of understanding by decision-makers of the value of zooplankton as indicators of ecosystem change. We provide recommendations for alleviating some of these impediments, and suggest a need for an easily understood example of global synchrony in zooplankton populations and the relation of those signals to large-scale climate drivers

An analysis of HIV risky behaviors of college students in Malawi: A case study of Bunda and The Polytechnic

Malawi’s first case of HIV was identified in 1985. Since then the Government, assisted by international aid organizations, has mounted campaign to promote HIV&AIDS awareness, offer Voluntary Counseling and Testing (VCT), and to prevent the spread of the Human Immunodeficiency Virus (HIV), which causes AIDS. The 2010 UNAIDS Report on Malawi shows that the spread of the epidemic has stabilized and even may be declining. The concern, however, is whether young men and women, who constitute the high-risk population of contracting the disease, such as college students, are paying heed to the campaign. This study of a small group of students at the Polytechnic and Bunda College campuses of the University of Malawi in 2008 examined the propensity of the students to engage in behaviors likely to expose them to HIV & AIDS. The study found that at least 20 percent of those studied exposed themselves through risky behavior, such as high alcohol consumption, unprotected sex and use of drugs, even though 80 percent were aware that such behaviors were likely to predispose them to the disease. Since the sample size was very small, we did not generalize our study to all university students in Malawi or even to all students on the campuses where the study was conducted. Furthermore, we recommend a broader study covering all constituent colleges of the University of Malawi, before significant recommendations can be made. The study, however, points to significant problems that need to be addressed before they get out of control, such as alcoholism and sex without condoms.Key words: Malawi, AIDS, HIV, University of Malawi, college student

Relativistic Hartree-Bogoliubov description of the deformed ground-state proton emitters

Ground-state properties of deformed proton-rich odd-Z nuclei in the region $59 \leq Z \leq 69$ are described in the framework of Relativistic Hartree Bogoliubov (RHB) theory. One-proton separation energies and ground-state quadrupole deformations that result from fully self-consistent microscopic calculations are compared with available experimental data. The model predicts the location of the proton drip-line, the properties of proton emitters beyond the drip-line, and provides information about the deformed single-particle orbitals occupied by the odd valence proton.Comment: 9 pages, RevTeX, 3 PS figures, submitted Phys. Rev. Letter

PASADENA Hyperpolarization of Succinic Acid for MRI and NMR Spectroscopy

We use the PASADENA (parahydrogen and synthesis allow dramatically enhanced nuclear alignment) method to achieve ^(13)C polarization of ∼20% in seconds in 1-^(13)C-succinic-d_2 acid. The high-field ^(13)C multiplets are observed as a function of pH, and the line broadening of C1 is pronounced in the region of the pK values. The ^2J_(CH), ^3J_(CH), and ^3J_(HH) couplings needed for spin order transfer vary with pH and are best resolved at low pH leading to our use of pH ∼3 for both the molecular addition of parahydrogen to 1-^(13)C-fumaric acid-d_2 and the subsequent transfer of spin order from the nascent protons to C1 of the succinic acid product. The methods described here may generalize to hyperpolarization of other carboxylic acids. The C1 spin−lattice relaxation time at neutral pH and 4.7 T is measured as 27 s in H_2O and 56 s in D_2O. Together with known rates of succinate uptake in kidneys, this allows an estimate of the prospects for the molecular spectroscopy of metabolism

Beta decay of 71,73Co; probing single particle states approaching doubly magic 78Ni

Low-energy excited states in 71,73Ni populated via the {\beta} decay of 71,73Co were investigated in an experiment performed at the National Superconducting Cyclotron Laboratory (NSCL) at Michigan State University (MSU). Detailed analysis led to the construction of level schemes of 71,73Ni, which are interpreted using systematics and analyzed using shell model calculations. The 5/2- states attributed to the the f5/2 orbital and positive parity 5/2+ and 7/2+ states from the g9/2 orbital have been identified in both 71,73Ni. In 71Ni the location of a 1/2- {\beta}-decaying isomer is proposed and limits are suggested as to the location of the isomer in 73Ni. The location of positive parity cluster states are also identified in 71,73Ni. Beta-delayed neutron branching ratios obtained from this data are given for both 71,73Co.Comment: Accepted for publication in PR

The Single-Particle Structure of Neutron-Rich Nuclei of Astrophysical Interest at the Ornl Hribf

The rapid nuetron-capture process (r process) produces roughly half of the elements heavier than iron. The path and abundances produced are uncertain, however, because of the lack of nuclear strucure information on important neutron-rich nuclei. We are studying nuclei on or near the r-process path via single-nucleon transfer reactions on neutron-rich radioactive beams at ORNL's Holifield Radioactive Ion Beam Facility (HRIBF). Owing to the difficulties in studying these reactions in inverse kinematics, a variety of experimental approaches are being developed. We present the experimental methods and initial results.Comment: Proceedings of the Third International Conference on Fission and Properties of Neutron-Rich Nucle