184 research outputs found
Knights, Dudes, and Shadow Steeds: Late Victorian Culture and the Early Cycling Clubs of New Orleans, 1881-1891
In the 1880s, two cycling clubs formed in New Orleansβthe New Orleans Bicycle Club in 1881 and the Louisiana Cycling Club in 1887. These clubs were institutions of Victorian middle class culture that, like other athletic clubs, arose from the conditions of urban modernity and Victorian class anxieties. The NOBC, like other American cycling clubs, conformed to Victorian values of order and respectability. The attitudes and activities of the LCC, whose membership was younger, reflected instead a counter-Victorian ethos. This paper examines these two clubs in the context of late Victorian culture in New Orleans as it responded both to the conditions of urban modernity common to American cities in this period and to the particular cultural situation of New Orleans at the end of the nineteenth century, including proximity to and amalgamation with the recently-dominant, non-Anglo culture of the Creoles
Synthesis of Functionalized Organic Molecules Using Copper Catalyzed Cyclopropanation, Atom Transfer Radical Reactions and Sequential Azide-Alkyne Cycloaddition
Copper-catalyzed regeneration in atom transfer radical addition (ATRA) utilizes reducing agents, which continuously regenerate the activator (CuI) from the deactivator (CuII) species. This technique was originally found for mechanistically similar atom transfer radical polymerization (ATRP) and its application in ATRA and ATRC has allowed significant reduction of catalyst loadings to ppm amounts. In order to broaden the synthetic utility of in situ catalyst regeneration technique, this was applied in copper-catalyzed atom transfer radical cascade reaction in the presence of free radical diazo initiators such as 2, 2\u27-azobis(isobutyronitrile) (AIBN) and (2, 2\u27-azobis(4-methoxy-2, 4-dimethyl valeronitrile) (V-70), which is the first part of this dissertation. This methodology can be translated to sequential ATRA/ATRC reaction, in which the addition of CCl4 to 1, 6-dienes results in the formation 5-hexenyl radical intermediate, which undergoes expedient 1, 5-ring closure in the exo- mode to form 1, 2-disubstituted cyclopentanes. When [CuII(TPMA)Cl][Cl] complex was used in conjunction with AIBN at 60 0C, cyclic products derived from the addition of CCl4 to 16-heptadiene, diallyl ether and N, NΒ-diallyl-2, 2, 2-trifluoroacetamide were synthesized in nearly quantitative yields using as low as 0.02 mol% of the catalyst (relative to 1, 6-diene). Even more impressive were the results obtained utilizing tertΒ-butyl-N, N-diallylcarbamate and diallyl malonate using only 0.01 mol% of the catalyst. Cyclization was also found to be efficient at ambient temperature when V-70 was used as the radical initiator. High product yields ( 80%) were obtained for mixtures having catalyst concentrations between 0.02 and 0.1 mol%. Similar strategy was also conducted utilizing unsymmetrical 1, 6-diene esters. It was found out that dialkyl substituted substrates (dimethyl-2-propenyl acrylate and ethylmethyl-2-propenyl acrylate) underwent 5-exocyclization producing halogenated g-lactones after the addition of CCl4 in the presence of 0.2 mol% of [CuII(TPMA)Cl][Cl]. Based on calculations using density functional theory (DFT) and natural bond order (NBO) analysis, cyclization of 1, 6-diene esters was governed by streoelectronic factors.
As a part of broadening the synthetic usefulness of in situ copper(I) regeneration, scope was further extended to sequential organic transformations. Based on previous studies, copper(I) catalyzed [3+2] azide-alkyne cycloaddition is commonly conducted via in situ reduction of CuII to CuI species by sodium ascorbate or ascorbic acid. At the same time, ATRA reactions have been reported to proceed efficiently via in situ reduction of CuII complex to the activator species or CuI complex has been fulfilled in the presence of ascorbic acid. Since the aforementioned reactions share similar catalyst in the form of copper(I), a logical step was taken in performing these reactions in one-pot sequential manner. Reactions involving azidopropyl methacrylate and 1-(azidomethyl)-4-vinylbenzene in the presence of a variety of alkynes and alkyl halides, catalyzed by as low as 0.5 mol-% of [CuII(TPMA)X][X] (X=Br-, Cl-) complex, proceeded efficiently to yield highly functionalized (poly)halogenated esters and aryl compounds containing triazolyl group in almost quantitative yields ( 90%). Additional reactions that were carried out utilizing tri-, di- and monohalogenated alkyl halides in the ATRA step provided reasonable yields of functionalized trriazoles. A slightly different approach involving a ligand-free catalytic system (CuSO4 and ascorbic acid) in the first step followed by addition of the TPMA ligand in the second step was applied in the synthesis of polyhalogened polytriazoles. Sequential reactions involving vinylbenzyl azide, tripropargylamine and polyhalogenated methane (CCl4 and CBr4) provided the desired products in quantitative yield in the presence of 10 mol% of the catalyst. Modest yields of functionalized polytriazoles were obtained from the addition of less active tri- and dihalogenated alkyl halides utilizing the same catalyst loading.
The last part focuses on copper(I) complexes, which were used catalysts in cyclopropanation reaction. One class represented cationic copper(I)/2, 2-bipyridine complexes with p-coordinated styrene [CuI(bpy)(p-CH2CHC6H5)][A] (A = CF3SO3- (1) and PF6- (2) and ClO4- (3). Structural data suggested that the axial coordination of the counterion in these complexes observed in the solid state weak to non-coordinating (2.4297(11) Γ
1, 2.9846(12) Γ
2, and 2.591(4) Γ
3). When utilized in cyclopropanation, complexes 1-3 provided similar product distribution suggesting that counterions have negligible effect on catalytic activity. Furthermore, the rate of decomposition of EDA in the presence of styrene catalyzed by 3 (kobs=(7.7Β±0.32)Β΄10-3 min-1) was slower than the rate observed for 1 (kobs=(1.4Β±0.041)Β΄10-2 min-1) or 2 (kobs=(1.0Β±0.025)Β΄10-2 min-1). On the other hand, tetrahedral copper(I) complexes with bipyridine and phenanthroline based ligands have been reported to have strongly coordinated tetraphenylborate anions. CuI(bpy)(BPh4), CuI(phen)(BPh4) and CuI(3, 4, 7, 8-Me4phen)(BPh4) complexes are the first examples in which BPh4- counterion chelates a transition metal center in bidentate fashion through h2 p-interactions with two of its phenyl rings. The product distribution revealed that the mole percent of trans and cis cyclopropanes were very similar. The observed rate constants (kobs) shown in for decomposition of EDA in the presence of externally added styrene were determined to be kobs=(1.5Β±0.12)Β΄10-3 min-1, (6.8Β±0.30)Β΄10-3 min-1 and (5.1Β±0.19)Β΄10-3 min-1
Knights, Dudes, and Shadow Steeds: Late Victorian Culture and the Early Cycling Clubs of New Orleans, 1881-1891
In the 1880s, two cycling clubs formed in New Orleansβthe New Orleans Bicycle Club in 1881 and the Louisiana Cycling Club in 1887. These clubs were institutions of Victorian middle class culture that, like other athletic clubs, arose from the conditions of urban modernity and Victorian class anxieties. The NOBC, like other American cycling clubs, conformed to Victorian values of order and respectability. The attitudes and activities of the LCC, whose membership was younger, reflected instead a counter-Victorian ethos. This paper examines these two clubs in the context of late Victorian culture in New Orleans as it responded both to the conditions of urban modernity common to American cities in this period and to the particular cultural situation of New Orleans at the end of the nineteenth century, including proximity to and amalgamation with the recently-dominant, non-Anglo culture of the Creoles
Imaging and Recording Subventricular Zone Progenitor Cells in Live Tissue of Postnatal Mice
The subventricular zone (SVZ) is one of two regions where neurogenesis persists in the postnatal brain. The SVZ, located along the lateral ventricle, is the largest neurogenic zone in the brain that contains multiple cell populations including astrocyte-like cells and neuroblasts. Neuroblasts migrate in chains to the olfactory bulb where they differentiate into interneurons. Here, we discuss the experimental approaches to record the electrophysiology of these cells and image their migration and calcium activity in acute slices. Although these techniques were in place for studying glial cells and neurons in mature networks, the SVZ raises new challenges due to the unique properties of SVZ cells, the cellular diversity, and the architecture of the region. We emphasize different methods, such as the use of transgenic mice and in vivo electroporation that permit identification of the different SVZ cell populations for patch clamp recording or imaging. Electroporation also permits genetic labeling of cells using fluorescent reporter mice and modification of the system using either RNA interference technology or floxed mice. In this review, we aim to provide conceptual and technical details of the approaches to perform electrophysiological and imaging studies of SVZ cells
Dissociation between short-term increased graft survival and long-term functional improvements in Parkinsonian rats overexpressing glial cell line-derived neurotrophic factor.
The present study was designed to analyse whether continuous overexpression of glial cell line-derived neurotrophic factor (GDNF) in the striatum by a recombinant lentiviral vector can provide improved cell survival and additional long-term functional benefits after transplantation of fetal ventral mesencephalic cells in Parkinsonian rats. A four-site intrastriatal 6-hydroxydopamine lesion resulted in an 80β90% depletion of nigral dopamine cells and striatal fiber innervation, leading to stable motor impairments. Histological analysis performed at 4 weeks after grafting into the GDNF-overexpressing striatum revealed a twofold increase in the number of surviving tyrosine hydroxylase (TH)-positive cells, as compared with grafts placed in control (green fluorescent protein-overexpressing) animals. However, in animals that were allowed to survive for 6 months, the numbers of surviving TH-positive cells in the grafts were equal in both groups, suggesting that the cells initially protected at 4 weeks failed to survive despite the continued presence of GDNF. Although cell survival was similar in both grafted groups, the TH-positive fiber innervation density was lower in the GDNF-treated grafted animals (30% of normal) compared with animals with control grafts (55% of normal). The vesicular monoamine transporter-2-positive fiber density in the striatum, by contrast, was equal in both groups, suggesting that long-term GDNF overexpression induced a selective down-regulation of TH in the grafted dopamine neurons. Behavioral analysis in the long-term grafted animals showed that the control grafted animals improved their performance in spontaneous motor behaviors to approximately 50% of normal, whereas the GDNF treatment did not provide any additional recovery
How Sleep Affects Recovery and Performance in Basketball: A Systematic Review
Background: Sleep is considered an essential component related to physiological and psychological recovery in athletes and particularly in basketball, given the impact of condensed travel and game schedules on player health and performance. Objective: The aim of this systematic review is to examine studies published to date on sleep and basketball performance. Methodology: All scientific articles that reported a relationship between sleep and its possible impact on performance in basketball are included. The research processes followed the PRISMA criteria, and the relevant articles were extracted (PubMed, WOS, Scopus) as of December 31, 2021. Results: Twenty-eight articles were selected for inclusion and data extraction, with 27 demonstrating that sleep is a vital component in the recovery of basketball players and their corresponding on-court performance. Three central themes that we identified: (1) the quality and extension of sleep (the better quality and more extension of sleep, better performance and lower probability of injury); (2) influence of the players circadian rhythm (tTravel and game scheduling do not currently facilitate or take this into account); and (3) higher training loads and/or increased stress may jeopardize a subsequent good night's sleep, which should be taken into account when scheduling practices and workouts. Conclusion: The current systematic review regarding sleep and basketball performance and highlights that there is a strong relationship between both variables. Collectively, the evidence supports the critical influence of sleep on player recovery and basketball performance and risk for injury
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