P-wave velocity of weathering profiles from a basalt climosequence: Implications for weathering on the mechanical properties of the critical zone

Thesis submitted in partial fulfillment of the requirements for the degree of Master of Science in Geology or Earth and Environmental Sciences, Department of Earth and Environmental SciencesWe characterize the critical zone structure across a basaltic climosequence in Kohala, Hawaii from shallow seismic refraction data. First-arrival P-waves surveys were tomographically inverted from an active source to create 2D profiles from eight locations of varying mean annual precipitation (MAP). P-wave velocities are interpreted as a weathering profile that is constrained by natural and manmade vertical exposures. Using MAP as a proxy for weathering magnitude on similar age exposures of Pleistocene-aged basalts, we evaluate differences in weathering as a primary control on critical zone architecture. The velocity-depth gradient decreases by a factor of 3 between 500 and 1000 mm/yr MAP and does not significantly change further with increasing precipitation between 1000 and 3000 mm/yr. Depth-to-unweathered bedrock increases between sites of 500 mm/yr to 1000 mm/yr MAP and may not be resolvable by the maximum depth of investigation on wet-side profiles (~ 15 m). Observed interbedded paleosols within exposures of the volcanic flow sequence at sites with MAP > 1000 mm/yr may explain both lower velocities at equivalent depths to dry sites, and the uniformity of velocity gradient with increasing MAP above a threshold value for soil development. Interbedded weak horizons within the depth profile may result in near-surface low velocity to much greater depth than would be predicted by a weathering profile produced by top-down progressive alteration from infiltration of surface water. Hence the main effect of climate is manifested not in the deepening of a near surface altered layer, but rather in the integrated exposure time and precipitation amount between eruptive phases leading to weathering horizons deep within the rock profile. Vii The mechanical implications of weathering influence hillslope stability, hillslope gradient, and the capacity for sediment transport by a variety of geomorphic processes.http://deepblue.lib.umich.edu/bitstream/2027.42/116847/1/VonVoigtlander_Jennifer_MS_2015.pdf1

Strong variation in weathering of layered rock maintains hillslope‐scale strength under high precipitation

The evolution of volcanic landscapes and their landslide potential are both dependent upon the weathering of layered volcanic rock sequences. We characterize critical zone structure using shallow seismic Vp and Vs profiles and vertical exposures of rock across a basaltic climosequence on Kohala peninsula, Hawai’i, and exploit the dramatic gradient in mean annual precipitation (MAP) across the peninsula as a proxy for weathering intensity. Seismic velocity increases rapidly with depth and the velocity–depth gradient is uniform across three sites with 500–600 mm/yr MAP, where the transition to unaltered bedrock occurs at a depth of 4 to 10 m. In contrast, velocity increases with depth less rapidly at wetter sites, but this gradient remains constant across increasing MAP from 1000 to 3000 mm/yr and the transition to unaltered bedrock is near the maximum depth of investigation (15–25 m). In detail, the profiles of seismic velocity and of weathering at wet sites are nowhere monotonic functions of depth. The uniform average velocity gradient and the greater depths of low velocities may be explained by the averaging of velocities over intercalated highly weathered sites with less weathered layers at sites where MAP > 1000 mm/yr. Hence, the main effect of climate is not the progressive deepening of a near‐surface altered layer, but rather the rapid weathering of high permeability zones within rock subjected to precipitation greater than ~1000 mm/yr. Although weathering suggests mechanical weakening, the nearly horizontal orientation of alternating weathered and unweathered horizons with respect to topography also plays a role in the slope stability of these heterogeneous rock masses. We speculate that where steep, rapidly evolving hillslopes exist, the sub‐horizontal orientation of weak/strong horizons allows such sites to remain nearly as strong as their less weathered counterparts at drier sites, as is exemplified by the 50°–60° slopes maintained in the amphitheater canyons on the northwest flank of the island. Copyright © 2017 John Wiley & Sons, Ltd.Seismic velocity profiles across a basalt climosequence in Hawai’i reveal that above a particular precipitation threshold, rapid weathering of high‐permeability layers produces intercalated low‐velocity horizons and dramatically lowers the average seismic velocity of the rock section. However, less permeable layers remain relatively unweathered and thus still contribute significantly to the mechanical competence of the profile, which may explain maintenance of steep‐walled canyons under high precipitation rates. Such observations challenge a top‐down model of progressive weathering (i.e. weakening) of the substrate and therefore suggest that high strength can be maintained even under high precipitation rates, if horizontally layered horizons of different weathering potential exist.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/143701/1/esp4290.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/143701/2/esp4290_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/143701/3/esp4290-sup-0001-SupplementaFiles_FINAL.pd

Atomistic Aspects of Diffusion and Growth on the Si and Ge (111) Surfaces

The stability of interfaces and the mechanisms of thin film growth on semiconductors are issues of central importance in electronic devices. These issues can only be understood through detailed study of the relevant microscopic processes. Experimental studies are able to provide detailed, atomic scale information for model systems. Theoretical analysis of experimental results is essential in explaining certain surprising observations and in providing guidance for optimizing conditions and methods of growth. We review recent theoretical work on the diffusion of adatoms, the structure of adsorbate monolayers, and their implications for growth on the Si and Ge (111) surfaces. The theoretical analysis consists of first-principles calculations of the total-energy and entropy factors for stable, metastable and saddle-point configurations. These calculations are supplemented by Monte Carlo simulations of simple models that afford direct contact with experimental observations.Comment: 30 pages, 11 figures (sent upon request, non-standard format

The search for the 'next' euphoric non-fentanil novel synthetic opioids on the illicit drugs market: current status and horizon scanning

Purpose: A detailed review on the chemistry and pharmacology of non-fentanil novel synthetic opioid receptor agonists, particularly N-substituted benzamides and acetamides (known colloquially as U-drugs) and 4-aminocyclohexanols, developed at the Upjohn Company in the 1970s and 1980s is presentedMethod: Peer-reviewed literature, patents, professional literature, data from international early warning systems and drug user fora discussion threads have been used to track their emergence as substances of abuse.Results: In terms of impact on drug markets, prevalence and harm, the most significant compound of this class to date has been U-47700 (trans-3,4-dichloro-N-[2-(dimethylamino)cyclohexyl]-N-methylbenzamide), reported by users to give short-lasting euphoric effects and a desire to re-dose. Since U-47700 was internationally controlled in 2017, a range of related compounds with similar chemical structures, adapted from the original patented compounds, have appeared on the illicit drugs market. Interest in a structurally unrelated opioid developed by the Upjohn Company and now known as BDPC/bromadol appears to be increasing and should be closely monitored.Conclusions: International early warning systems are an essential part of tracking emerging psychoactive substances and allow responsive action to be taken to facilitate the gathering of relevant data for detailed risk assessments. Pre-emptive research on the most likely compounds to emerge next, so providing drug metabolism and pharmacokinetic data to ensure that new substances are detected early in toxicological samples is recommended. As these compounds are chiral compounds and stereochemistry has a large effect on their potency, it is recommended that detection methods consider the determination of configuration

Selectivity of ligand binding to opioid receptors in brain membranes from the rat, monkey and guinea pig

Conditions for the equilibrium binding to opioid receptor of [3H[sufentanil ([mu] selective), [3H][D-Pen2, D-Pen5]enkephalin ([delta] selective), and [3H]U69,593 ([kappa] selective) were established in membranes from rat brain cerebrum, monkey cortex, or guinea pig cerebellum. The selectivity index of various opioid alkaloids and peptides in binding to the [mu], [delta], or [kappa] opioid receptors was expressed as the ratio of their EC50 values in displacing two selective radiolabeled ligands: [3H]sufentanil/[3H](D-Pen2, D-Pen5)enkephalin (selectivity: [mu]/[delta]), [3H]sufentanil/[3H]U69,593 (selectivity: [mu]/[kappa]), or [3H][D-Pen2, D-Pen5]enkephalin/[3H]U69,593 (selectivity: [delta]/[kappa]). High resolution in binding selectivity was observed: in rat brain the [mu]/[delta] selectivity for Tyr-D-Ala-Gly-(Me)Phe-Gly-ol and sufentanil were 0.02 and 0.03, whereas for [D-Pen2, D-Pen5]enkephalin and ICI 174,864 they were 1200 and 998. Compared to [mu] opiates, the specific binding of [delta] and [kappa] agonists was less sensitive to sodium. The results describe a routinely applicable methodological approach for the assessment of selective ligand binding to the [mu], [delta] and [kappa] opioid receptors in rodent and monkey brain membranes.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/27337/1/0000362.pd

Mu, delta, and kappa opioid receptor mRNA expression in the rat CNS: An in situ hybridization study

The Μ, Δ, and Κ opioid receptors are the three main types of opioid receptors round in the central nervous system (CNS) and periphery. These receptors and the peptides with which they interact are important in a number of physiological functions, including analgesia, respiration, and hormonal regulation. This study examines the expression of Μ, Δ, and Κ receptor mRNAs in the rat brain and spinal cord using in situ hybridization techniques. Tissue sections were hybridized with 35 S-labeled cRNA probes to the rat Μ (744–1, 064 b), Δ (304–1,287 b), and Κ (1,351–2,124 b) receptors. Each mRNA demonstrates a distinct anatomical distribution that corresponds well to known receptor binding distributions. Cells expressing Μ receptor mRNA are localized in such regions as the olfactory bulb, caudate-putamen, nucleus accumbens, lateral and medial septum, diagonal band of Broca, bed nucleus of the stria terminalis, most thalamic nuclei, hippocampus, amygdala, medial preoptic area, superior and inferior colliculi, central gray, dorsal and median raphe, raphe magnus, locus coeruleus, parabrachial nucleus, pontine and medullary reticular nuclei, nucleus ambiguus, nucleus of the solitary tract, nucleus gracilis and cuneatus, dorsal motor nucleus of vagus, spinal cord, and dorsal root ganglia. Cellular localization of Δ receptor mRNA varied from Μ or Κ, with expression in such regions as the olfactory bulb, allo- and neocortex, caudate-putamen, nucleus accumbens, olfactory tubercle, ventromedial hypothalamus, hippocampus, amygdala, red nucleus, pontine nuclei, reticulotegmental nucleus, motor and spinal trigeminal, linear nucleus of the medulla, lateral reticular nucleus, spinal cord, and dorsal root ganglia. Cells expressing, Κ receptor mRNA demonstrate a third pattern of expression, with cells localized in regions such as the claustrum, endopiriform nucleus, nucleus accumbens, olfactory tubercle, medial preoptic area, bed nucleus of the stria terminalis, amygdala, most hypothalamic nuclei, median eminence, infundibulum, substantia nigra, ventral tegmental area, raphe nuclei, paratrigeminal and spinal trigeminal, nucleus of the solitary tract, spinal cord, and dorsal root ganglia. These findings are discussed in relation to the physiologica functions associated with the opioid receptors.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/50064/1/903500307_ftp.pd

Differential effects of systemically administered nor-binaltorphimine (nor-BNI) on κ-opioid agonists in the mouse writhing assay

The opioid antagonist effects of systemically administered nor-binaltorphimine (nor-BNI) were evaluated against the kappa agonists CI-977, U69,593, U50,488, ethylketocyclazocine (EKC), Mr2034 and bremazocine, the mu agonist morphine and the alkaloid delta agonist BW-373U86 in the acetic acid-induced writhing assay in mice. All eight agonists completely and dose-dependently inhibited writhing. Antagonism of CI-977 was apparent 1 h after administration of 32 mg/kg nor-BNI, peaking after 4 h and was maintained for at least 4 weeks; no antagonist effects of nor-BNI were apparent after 8 weeks. Nor-BNI (32 mg/kg) caused little or no antagonism of morphine or BW-373U86 at 1 h and none at 24 h after nor-BNI administration. Subsequently, dose-effect curves for CI-977, U50,488, U69,593, EKC, Mr2034 and bremazocine were determined 24 h after pretreatment with 3.2, 10 and 32 mg/kg nor-BNI. Pretreatment with 3.2 mg/kg nor-BNI produced significant antagonism of all six kappa agonists, suggesting that their antinociceptive effects were mediated at least in part by nor-BNI-sensitive kappa receptors. At higher doses, nor-BNI dose-depend-ently shifted the agonist dose-effect curves of CI-977, U50,488, U69,593 and bremazocine, but not those of EKC and Mr2034, suggesting that the latter compounds may be producing effects via nor-BNI-insensitive receptors. Mu receptor involvement was demonstrated following a 24 h pretreatment with 32 mg/kg β -FNA in combination with nor-BNI, which significantly increased the degree of antagonism of Mr2034 and EKC from that seen with nor-BNI alone. Hence, SC administered nor-BNI selectively antagonized agonist activity mediated through kappaopioid receptors without differentiating between kappa subtypes. Nor-BNI also enabled the mu agonist activity of proposed kappa agonists to be measured.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/46343/1/213_2005_Article_BF02245071.pd

A Survey Of Neo-babylonian History.

PhDAncient civilizationsUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/179527/2/6408220.pd