Economic Sanctions and the Survival of Autocratic Regimes

Senior Project submitted to The Division of Social Studies of Bard College

The distribution of reaction rates and activation energies on catalytic surfaces: Exchange reaction between gaseous benzene and benzene adsorbed on platinum

A mathematical derivation for the calculation of the distribution function of rate constants and activation energies for an isotopic exchange reaction between chemical species adsorbed on a solid surface and in the surrounding gas phase is presented. Starting from experimental kinetic isotherms, giving the rate of exchange as a function of time at various temperatures, it is shown how it is possible to derive the distribution functions of the rate constants and activation energies. The technique is applied to the exchange reaction between benzene molecules adsorbed on Pt black and molecules present in the gas phase. Experimental results on the rate of this exchange, obtained by means of C-14 labeled benzene, have been collected at 40 [deg], 60 [deg], 80 [deg], and 100 [deg] C, at constant surface coverage. The range of activation energies for the exchange reaction was found to be from about 10 to 35 kcal/mole, while the pre-exponential factor varied from about 107 to 1026 min-1. Additional observations on the chemisorption of benzene on Pt black are presented. The effects of various pretreatments of the Pt surface and of aging of the chemisorbed benzene on the exchange rate are discussed.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/32196/1/0000254.pd

Current and prospective pharmacological targets in relation to antimigraine action

Migraine is a recurrent incapacitating neurovascular disorder characterized by unilateral and throbbing headaches associated with photophobia, phonophobia, nausea, and vomiting. Current specific drugs used in the acute treatment of migraine interact with vascular receptors, a fact that has raised concerns about their cardiovascular safety. In the past, α-adrenoceptor agonists (ergotamine, dihydroergotamine, isometheptene) were used. The last two decades have witnessed the advent of 5-HT1B/1D receptor agonists (sumatriptan and second-generation triptans), which have a well-established efficacy in the acute treatment of migraine. Moreover, current prophylactic treatments of migraine include 5-HT2 receptor antagonists, Ca2+ channel blockers, and β-adrenoceptor antagonists. Despite the progress in migraine research and in view of its complex etiology, this disease still remains underdiagnosed, and available therapies are underused. In this review, we have discussed pharmacological targets in migraine, with special emphasis on compounds acting on 5-HT (5-HT1-7), adrenergic (α1, α2, and β), calcitonin gene-related peptide (CGRP 1 and CGRP2), adenosine (A1, A2, and A3), glutamate (NMDA, AMPA, kainate, and metabotropic), dopamine, endothelin, and female hormone (estrogen and progesterone) receptors. In addition, we have considered some other targets, including gamma-aminobutyric acid, angiotensin, bradykinin, histamine, and ionotropic receptors, in relation to antimigraine therapy. Finally, the cardiovascular safety of current and prospective antimigraine therapies is touched upon

Neuroprotection by adenosine in the brain: From A1 receptor activation to A2A receptor blockade

Adenosine is a neuromodulator that operates via the most abundant inhibitory adenosine A1 receptors (A1Rs) and the less abundant, but widespread, facilitatory A2ARs. It is commonly assumed that A1Rs play a key role in neuroprotection since they decrease glutamate release and hyperpolarize neurons. In fact, A1R activation at the onset of neuronal injury attenuates brain damage, whereas its blockade exacerbates damage in adult animals. However, there is a down-regulation of central A1Rs in chronic noxious situations. In contrast, A2ARs are up-regulated in noxious brain conditions and their blockade confers robust brain neuroprotection in adult animals. The brain neuroprotective effect of A2AR antagonists is maintained in chronic noxious brain conditions without observable peripheral effects, thus justifying the interest of A2AR antagonists as novel protective agents in neurodegenerative diseases such as Parkinson’s and Alzheimer’s disease, ischemic brain damage and epilepsy. The greater interest of A2AR blockade compared to A1R activation does not mean that A1R activation is irrelevant for a neuroprotective strategy. In fact, it is proposed that coupling A2AR antagonists with strategies aimed at bursting the levels of extracellular adenosine (by inhibiting adenosine kinase) to activate A1Rs might constitute the more robust brain neuroprotective strategy based on the adenosine neuromodulatory system. This strategy should be useful in adult animals and especially in the elderly (where brain pathologies are prevalent) but is not valid for fetus or newborns where the impact of adenosine receptors on brain damage is different

The Distribution Of Reaction Rates And Activation Energies For The Exchange Reaction Between Gaseous Benzene And Benzene Chemisorbed On A Platinum Surface.

PhDChemical engineeringUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/185788/2/6306884.pd

Titanium Ti-6Al-4V

Titanium alloys, such as Ti-6A1-4V, used as biomaterials possess great characteristics compared to other alloys such as stainless steel alloys. Characteristics such as biocompatibility, enhanced corrosion, strain, and fatigue resistance provide amazing benefits from these alloys. Providing an understanding of Ti used in biomedical applications and production can provide insight into its benefits and limitations as well as the areas of potential improvement for future study.https://scholarsjunction.msstate.edu/metallurgy/1015/thumbnail.jp

Delivering Bioinformatics Training: Bridging the Gaps Between Computer Science and Biomedicine Abstract

Biomedical researchers have always sought innovative methodologies to elucidate the underlying biology in their experimental models. As the pace of research has increased with new technologies that ‘scale-up ’ these experiments, researchers have developed acute needs for the information technologies which assist them in managing and processing their experiments and results into useful data analyses that support scientific discovery. The application of information technology to support this discovery process is often called bioinformatics. We have observed a ‘gap ’ in the training of those individuals who traditionally aid in the delivery of information technology at the level of the end-user (e.g. a systems analyst working with a biomedical researcher) which can negatively impact the successful application of technological solutions t