Chemoenzymatic epoxidation of citronellol catalyzed by lipases

AbstractThe chemoenzymatic epoxidation of a terpene alcohol, citronellol, is reported. Some experimental conditions, such as the use of lipases from different sources, oxidizing agents (H2O2 or urea–hydrogen peroxide, UHP), reaction time, acyl donor type (C6–C16), temperature (15–40°C) and the influence of organic media, were evaluated. In most cases, citronellol oxide 2 or the ester citronellol oxide 3 were obtained. Depending on the reaction conditions, high yields of products 2 or 3 were obtained (>99%). CAL-B was the most effective catalyst in this reaction. For epoxide 2, the highest yields of 80% and 77% were obtained at 20°C and 25°C, respectively, using UHP as an oxidizing agent and octanoic acid as an acyl donor. The organic medium appears to be one of the most important parameters in the reaction. Using chloroform or dichloromethane, product 2 was obtained at a >99% yield after 24h. When different mixtures consisting of varied organic solvents and an imidazolium-based ionic liquid (IL) were used, the results were dependent on both the solvent and IL counter-ion (18–75%)

BYOD for physics lab: Studying Newton's law of cooling with a smartphone

In this paper we discuss a simple and inexpensive method to introduce students to Newton''s law of cooling using only their smartphones, according to the Bring-Your-Own-Device philosophy. A popular experiment in basic thermodynamics, both at a high-school and at University level, is the determination of the specific heat of solids and liquids using a water calorimeter, resourcing in many cases to a mercury thermometer. With our approach the analogical instrument is quickly turned into a digital device by analyzing the movement of the mercury with a video tracker. Tus, using very simple labware and the students'' smartphones or tablets, it is possible to observe the decay behavior of the temperature of a liquid lef to cool at room temperature. Te dependence of the time constant with the mass and surface of the liquid can be easily probed, and the results of the different groups in the classroom can be brought together to observe the linear dependence

First exposure to Arduino through peer-coaching: Impact on students' attitudes towards programming

In this paper we report the work that jeKnowledge (Júnior Empresa da Faculdade de Ciências e Tecnologias da Universidade de Coimbra), a student-led initiative, has done in the ‘jeKnowledge academy’ courses to actively engage Portuguese high-school students in STEM education through hands-on projects based on the low-cost Arduino platform. F2F activities, based on a peer-assisted learning strategy, were complemented with tutorials and more advanced project suggestions in a blog. Pre and post surveys on students'' attitudes towards programming and peer-coaching were administered to pre-university and first year college participants, finding an overall increase in the Likert scale for all the programming-related constructs under study (confidence, interest, gender, usefulness and professional) after the introductory course. As regards the peer-based learning approach, younger students seemed to be more eager to be taught in a less formal way than their older counterparts. The course resulted in high degrees of satisfaction for both the student tutors and their tutees

The effect of a tangential frictional force on rotating disks: an experimental approach

This paper describes an experiment with two touching rotating disks, whose movement is followed by video analysis. Within the disks’ movements, there are intervals with sliding and intervals without sliding, that is, intervals with frictional forces between the touching surfaces and intervals without it. This system configuration allows for measurement of the changeable magnitudes and directions of frictional forces (much more difficult to set up with translational motion). This activity may be used to combat students misconceptions of “frictional force always opposes the motion” and “between the same two bodies, one gets the same frictional force,” commonly found in the classroom, or just to reinforce the rotational dynamics relationships

The Kumaraswamy-G Poisson Family of Distributions

For any baseline continuous G distribution, we propose a new generalized family called the Kumaraswamy-G Poisson (denoted with the prefix “Kw-GP”) with three extra positive parameters. Some special distributions in the new family such as the Kw-Weibull Poisson, Kw-gamma Poisson and Kw-beta Poisson distributions are introduced. We derive some mathematical properties of the new family including the ordinary moments, generating function and order statistics. The method of maximum likelihood is used to fit the distributions in the new family. We illustrate its potentiality by means of an application to a real data set

Development and application of I_SUM : an index of sustainable urban mobility

This work describes the construction process of an Index of Sustainable Urban Mobility (I_SUM). Important aspects regarding its application as a mobility planning and management supporting tool are also discussed. The index is based on a hierarchy of criteria built essentially with data obtained from planners and technicians of eleven cities, what resulted in eighty-seven Indicators forming thirty-seven Themes, under nine Domains. Weights for the Themes and Domains were obtained through a panel of experts. A viability analysis of the index application was carried out in a city with around 220,000 inhabitants located in the state of São Paulo, Brazil. The analysis of the results has shown that a significant number of indicators could be calculated in the short term and with good quality data in the studied city. The main conclusion drawn from the application was the confirmation that I_SUM is flexible enough to be applied not only in a developing country medium-sized city, but also in cities with diverse characteristics. It is important to highlight the fact that the tool also gives the opportunity to assess the relative contribution of any specific aspects of mobility to the Social, Economic, and Environmental dimensions of sustainability. That I_SUM feature can be used to help in the formulation of either integrated or stand-alone policies per sector aiming at the development of the sustainable urban mobility. Moreover, it can help in the public participation process due to the possibility of building up scenarios based on hypothetical changes of the indicator values