Preparation of conformationally restricted β2,2- and β2,2,3-amino esters and derivatives containing an all-carbon quaternary center

Abstract: β-Amino acids are routinely incorporated into peptidic drugs to increase their stability and to incur conformational biases. However, the synthesis of highly substituted β-amino acids still represents a great challenge. A new approach to their preparation is reported involving a Vilsmeier–Haack reaction with nonaromatic carbon nucleophiles. The highly challenging preparation of contiguous tertiary and all-carbon quaternary centers was successfully used to generate several β2,2,3-amino esters, such as derivatives of homoproline, homoalanine, and homopipecolinic esters

L'éternel retour du même et la volonté de puissance chez Nietzsche

L'objectif de ce travail de recherche sera de confirmer ou d'infirmer la possibilité d'interpréter la philosophie de Nietzsche à titre de cosmobiologie à partir de son oeuvre posthume. Pour ce faire, nous étudierons en premier lieu la méthode par laquelle Nietzsche érige la structure épistémologique de sa philosophie. Nous verrons que cette méthode mène tout droit au concept de volonté de puissance. Conséquemment, nous définirons soigneusement le rôle et la nature conceptuelle de la volonté de puissance pour la philosophie de Nietzsche par l'intermédiaire d'une critique épistémique de la mécanique classique de son époque. Après avoir déterminé conceptuellement la nature de la volonté de puissance, nous tenterons de rendre compte de celle-ci sous la forme cohérente d'une cosmologie de l'éternel retour du même afin d'éviter que la volonté de puissance ne devienne une thèse purement métaphysique. En conclusion, nous verrons que le concept de vie dans la philosophie de Nietzsche ne parvient pas à lui seul à expliquer la cosmologie de l'éternel retour du même. Corolairement, nous devrons infirmer l'hypothèse selon laquelle nous pourrions interpréter la philosophie de Nietzsche à titre de cosmobiologi

On the control and automation of a novel membrane electro-bioreactor (MEBR)

The membrane electro-bioreactor (MEBR) has demonstrated to be effective in the treatment of wastewater, where superior quality of the effluent was achieved. The MEBR is a compact hybrid unit that uses several processes, such as activated sludge, membrane filtration, and electrokinetic phenomena. The objective of this study was to improve the treatment of wastewater by monitoring and controlling MEBR processes on-line, which was accomplished by implementing an automation system. As the complexity of the processes increase in the treatment wastewater, it is difficult to their guarantee performance; the automation system maintained the wastewater treatment to satisfactory performance. Automation of the system was accomplished through control algorithms using on-line instrumentation of critical parameters such as: dissolved oxygen, aeration, and water levels. The MEBR system demonstrated removal of carbon and nutrients (phosphorus, and nitrogen) for water recovery. Automated aeration ensured biological treatment without excessive aeration, fluctuating low dissolved oxygen concentrations allowed for simultaneous aerobic and anoxic conditions without inhibiting biological treatment. Automated electrokinetic improved nutrient removal with reduced energy consumption, also biological treatment was not inhibited. Electrokinetic demonstrated even lower than previously observed energy consumption. A user interface was implemented to allow on-site monitoring of the processes as well as allow adjustment of process parameters. Having a completely automated MEBR allowed this novel wastewater treatment system to be implemented in a remote location, as a decentralized system, in order to simulate an effective wastewater treatment system which may be applied to improve the quality of life for the secluded population of northern Canada and Quebec

Développement d’un système d’actionnement utilisant la combustion d’une source d’énergie chimique pour la robotique mobile

Les systèmes d’actionnement couramment utilisés sur les systèmes de robotiques mobiles tels que les exosquelettes ou les robots marcheurs sont majoritairement électriques. Les batteries couplées à des moteurs électriques souffrent toutefois d’une faible densité de stockage énergétique et une faible densité de puissance, ce qui limite l’autonomie de ces dispositifs pour une masse de système donnée. Une étude comparative des systèmes d’actionnement potentiels a permis de déterminer que l’utilisation d’une source d’énergie chimique permettait d’obtenir une densité de stockage énergétique supérieure aux batteries. De plus, il a été déterminé que l’utilisation de la combustion directement dans un actionneur pneumatique souple permettrait d’obtenir une densité de puissance beaucoup plus élevée que celle des moteurs électriques. La conception, la fabrication et la caractérisation de plusieurs types d’actionneurs pneumatiques pressurisés directement par la combustion d’une source d’énergie chimique ont permis d’évaluer la faisabilité de l’approche, dans un contexte de robotique mobile, plus précisément pour des tâches de locomotion. Les paramètres permettant d’obtenir une efficacité énergétique élevée ont été étudiés. Il a été démontré que le ratio de compression et le ratio d’expansion doivent être optimisés. De plus, comme les pertes thermiques sont le mécanisme de perte dominant, le ratio d’équivalence devrait être réduit au minimum. Parmi les carburants usuels, l’hydrogène permet d’atteindre les valeurs de ratio d’équivalence les plus faibles, ce qui en fait un choix de carburant idéal. Les résultats expérimentaux ont été utilisés pour corréler un modèle analytique d’un actionneur pneumatique à combustion. Ce modèle analytique est par la suite utilisé pour vérifier la faisabilité théorique de l’utilisation de l’approche d’actionnement pour fournir la puissance à un dispositif d’assistance à la locomotion

Contrasting nutritional acclimation of sugar maple (Acer saccharum Marsh.) and red maple (Acer rubrum L.) to increasing conifers and soil acidity as demonstrated by foliar nutrient balances

Sugar maple (Acer saccharum Marshall, SM) is believed to be more sensitive to acidic and nutrient-poor soils associated with conifer-dominated stands than red maple (Acer rubrum L., RM). Greater foliar nutrient use efficiency (FNUE) of RM is likely the cause for this difference. In the context of climate change, this greater FNUE could be key in favoring northward migration of RM over SM. We used the concept of foliar nutrient balances to study the nutrition of SM and RM seedlings along an increasing gradient in forest floor acidity conditioned by increasing proportions of conifers (pH values ranging from 4.39 under hardwoods, to 4.29 under mixed hardwood-conifer stands and 4.05 under conifer-dominated stands). Nutrients were subjected to isometric log-ratio (ilr) transformation, which views the leaf as one closed system and considers interactions between nutrients. The ilr method eliminates numerical biases and weak statistical inferences based on raw or “operationally” log-transformed data. We analyzed foliar nutrients of SM and RM seedlings and found that the [Ca,Mg,K| P,N] and [Ca,Mg| K] balances of SM seedlings were significantly different among soil acidity levels, whereas they did not vary for RM seedlings. For SM seedlings, these differences among soil acidity levels were due to a significant decrease in foliar Ca and Mg concentrations with increasing forest floor acidity. Similar differences in foliar balances were also found between healthy and declining SM stands estimated from literature values. Conversely, foliar balances of RM seedlings did not differ among soil acidity levels, even though untransformed foliar nutrient concentrations were significantly different. This result highlights the importance of using ilr transformation, since it provides more sensitive results than standard testing of untransformed nutrient concentrations. The lower nutrient requirements of RM and its greater capacity to maintain nutrient equilibrium are factors that could explain its competitive success and recent northward expansion. This study underscores the importance of using nutrient balances to study the redistribution of plant species in natural ecosystems under climate change

Near Peripheral Motion Detection Threshold Predicts Detection Failure Accident Risk in Younger and Older Drivers

Motion contrast thresholds for 0.4 cycle/degree drifting Gabor stimuli were assessed at 15-degrees eccentricity for 16 younger drivers (ages 24 to 42), and 15 older drivers (ages 65 to 84), using a temporal two-alternative forced choice staircase procedure. Two self-report questionnaires assessed detection failure accident risk—the Driver Perception Questionnaire (DPQ5), and an abridged Aging Driver Questionnaire (ADQ15). The UFOV® test battery was also administered. Mean peripheral motion contrast thresholds (PMCT) of younger and older participants were –39.3 dB and –33.8 dB, respectively. For younger drivers, the correlation between PMCT and DPQ5 scores was .62 (p\u3c.01), and between DPQ5 and ADQ16 (new and validated self-report measures, respectively) was .59 (p\u3c.01). For older drivers, correlation between PMCT and DPQ5 scores was .49 (p\u3c.01), between DPQ5 and ADQ16 was .73 (p\u3c.01), and between PMCT and age was .49 (p\u3c.05). For drivers overall, correlation was .48 (p\u3c.01) between PMCT and DPQ5 scores, .63 (p\u3c.0001) between DPQ5 and ADQ16, and .69 (p\u3c.0001) between PMCT and age. For drivers overall, correlation was .30 (p\u3c.05) between UFOV1 and age, .67 (p\u3c.0001) between UFOV2 and age, .56 (p\u3c.001) between UFOV2 and PMCT, .80 (p\u3c.0001) between UFOV3 and age, and .58 (p\u3c.001) between UFOV3 and PMCT. Holding age constant, partial correlation of PMCT with DPQ5 was .55 (p\u3c.001), and of PMCT with ADQ15 was .39 (p\u3c.05). PMCT significantly predicted self-reported driving performance in a laboratory setting, and worsened significantly with age. PMCT assessment should be made practicable. Informing high-risk drivers may encourage appropriate risk reduction countermeasures

Does shyness interact with peer group affiliation in predicting substance use in adolescence?

Cigarette use and binge drinking are risky behaviors emerging during adolescence. Although many beneficial factors are well documented, studies linking shyness to substance use are somehow conflicting, which may be due to the contribution of moderators. Therefore, the present study has 2 objectives: (a) to prospectively analyze the association between shyness and substance use during adolescence, and (b) to test the moderating role of peer group affiliation on the relationship between shyness and substance use. Participants are 1447 adolescents from the Quebec Longitudinal Study of Child Development, a representative cohort of single-birth children born between 1997 and 1998 in the province of Quebec, Canada. Shyness was assessed at age 12 years. Peer group affiliation, as well as past year cigarette use and binge drinking were assessed at age 15 years. Logistic regressions were used to analyze the data. All analyses were carried out using weighted data accounting for the complex multistage sample design. Results show that shyness negatively predicts the use of tobacco and the occurrence of binge drinking while controlling for confounding variables. However, shyness does not interact with peer group affiliation in predicting substance use. This is the first study that confirms the presence of a negative relationship between shyness and substance use during adolescence over a 3-year period. Results suggest that shyness could exert a beneficial effect against substance use notwithstanding the adolescent’s social context