Coherent monochromatic phonons in highly purified semiconducting single-wall carbon nanotubes

We have used a femtosecond pump-probe impulsive Raman technique to explore the polarization dependence of coherent optical phonons in highly purified and aligned semiconducting single-wall carbon nanotubes (SWCNTs). Coherent phonon spectra for the radial breathing modes (RBMs) exhibit a different monochromatic frequency between the film and solution samples, indicating the presence of differing exciton excitation processes. By varying the polarization of the incident pump beam on the aligned SWCNT film, we found that the anisotropy of the coherent RBM excitation depends on the laser wavelength, which we consider to be associated with the resonant and off-resonant behavior of RBM excitation

Women’s economic empowerment : a review of evidence on enablers and barriers

This rapid evidence review summarizes the evidence that women’s economic empowerment (WEE) promotes economic growth, firm productivity, and human development. It also reviews the key enablers and barriers to WEE. We have followed strict criteria regarding the rigor of studies included in this review, noting inconsistencies in the scale and quality of evidence on key questions about WEE. We draw on this evidence to distill key findings to support the United Nations High-Level Panel on Women’s Economic Empowerment’s priority setting and make recommendations for policy interventions or important topics requiring further research

A Metabolomic Analysis of Omega-3 Fatty Acid-Mediated Attenuation of Western Diet-Induced Nonalcoholic Steatohepatitis in LDLR[superscript -/-] Mice

Background: Nonalcoholic steatohepatitis (NASH) is a progressive form of nonalcoholic fatty liver disease and a risk factor for cirrhosis, hepatocellular carcinoma and liver failure. Previously, we reported that dietary docosahexaenoic acid (DHA, 22:6,n-3) was more effective than eicosapentaenoic acid (EPA, 20:5,n-3) at reversing western diet (WD) induced NASH in LDLR-/- mice. Methods: Using livers from our previous study, we carried out a global non-targeted metabolomic approach to quantify diet-induced changes in hepatic metabolism. Results: Livers from WD + olive oil (WD + O)-fed mice displayed histological and gene expression features consistent with NASH. The metabolomic analysis of 320 metabolites established that the WD and n-3 polyunsaturated fatty acid (PUFA) supplementation had broad effects on all major metabolic pathways. Livers from WD + O-fed mice were enriched in saturated (SFA) and monounsaturated fatty acids (MUFA), palmitoylsphingomyelin, cholesterol, n-6 PUFA, n-6 PUFA-containing phosphoglycerolipids, n-6 PUFA-derived oxidized lipids (12-HETE) and depleted of C20-22 n-3 PUFA-containing phosphoglycerolipids, C20-22 n-3 PUFA-derived oxidized lipids (18-HEPE, 17,18-DiHETE) and S-lactoylglutathione, a methylglyoxal detoxification product. WD + DHA was more effective than WD + EPA at attenuating WD + O-induced changes in NASH gene expression markers, n-6 PUFA and oxidized lipids, citrate and S-lactosyl glutathione. Diet-induced changes in hepatic MUFA and sphingolipid content were associated with changes in expression of enzymes involved in MUFA and sphingolipid synthesis. Changes in hepatic oxidized fatty acids and S-lactoylglutathione, however, correlated with hepatic n-3 and n-6 C20-22 PUFA content. Hepatic C20-22 n-3 PUFA content was inversely associated with hepatic α-tocopherol and ascorbate content and positively associated with urinary F2- and F3-isoprostanes, revealing diet effects on whole body oxidative stress. Conclusion: DHA regulation of hepatic SFA, MUFA, PUFA, sphingomyelin, PUFA-derived oxidized lipids and Slactoylglutathione may explain the protective effects of DHA against WD-induced NASH in LDLR-/- mice

Enhancing Understanding of Oxygenic Photosynthesis Using Two Dimensional Electronic Spectroscopy

Many aspects of energy and charge transfer in oxygenic photosynthesis are still poorly understood at both the level of single pigments and multi-pigment complexes. At the single pigment level, chlorophylls and chlorophyll-like pigments (including bacteriochlorophyll, pheophytin, etc.) exhibit similar structure in the Q-band absorption region that has long been accepted to have correspondingly similar electronic structure. However, evidence has been mounting that suggests that despite the qualitative similarities between chlorophyll-like pigments they are in fact unique in their electronic structure. On larger length scales, key processes in photosynthesis such as stable charge separation, are accomplished via multiple pigments embedded within a protein matrix acting in concert. Understanding all the intermediate states that occur during charge separation in oxygenic photosynthesis, particularly in the photosystem II complex, is challenging due to the large degree of spectral overlap between chlorophyll and chlorophyll-like pigments. This has made it nearly impossible to disentangle individual pigment contributions from spectroscopic signatures and understand the structure-function relationship in this important system. This thesis presents my work that capitalizes on the advantages of two-dimensional electronic spectroscopy (2DES), particularly its ability to maintain simultaneous high temporal and spectral resolution, and incorporates further modifications to the technique that allow for studying oxygenic photosynthesis at the single pigment and multi-pigment regimes. By integrating polarization control among the multi-laser pulse experiment I was able to compare the underlying electronic and vibrational energy level structure of bacteriochlorophyll a and chlorophyll a to show how the structure of chlorophyll a deviates from the simple Gouterman model framework and lends support to the argument for vibronic models. Results of this work were supported by theoretical calculations performed by our collaborators from the group of Eitan Geva in the Chemistry Department at the University of Michigan and the group of Barry Dunietz at Kent State University. Futhermore, I used a multi-spectral 2DES technique, exciting across the Q$_y$ band and probing the higher energy Q$_x$ and carotenoid transitions in the photosystem II reaction center. The 2DES spectra reveal cross peaks between the highly congested Q$_y$ band and Q$_x$ and carotenoid transitions, providing insight into the contributions of the individual pigments to the absorption in the Q$_y$ region. Analysis of the kinetics of the 2DES data allows us to test the proposed two-pathway model of charge separation in the photosystem II reaction center. The results of these studies emphasize the importance of the feed-back between experiment and theory in building and refining an overall understanding of oxygenic photosynthesis. We anticipate that the information obtained in these studies will contribute to building the new models of the underlying energy structure of single pigments and excitonic interactions that lead to energy and charge transfer in the reaction center of oxygenic photosynthetic complexes.PHDApplied PhysicsUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttps://deepblue.lib.umich.edu/bitstream/2027.42/151557/1/emaret_1.pd

THE "INTRODUCTORY SOCIOLOGY SURVEY": AN INSTRUMENT TO FACILITATE TEACHING EFFECTIVENESS

Many colleges and universities in recent years have shown an increased interest in the teaching effectiveness of their faculty. College-wide teacher rating instruments have become commonplace in many classrooms, including the introductory sociology classroom. Sociologists often express concern over these collegewide instruments for at least two reasons. First, sociologists have been rated generally by students as poor teachers (Linsky and Straus, 1973). Second, the applicability of these broad instruments to varied courses and circumstances is often questionable (Goldsmid and Wilson, 1980)