Stereoselective synthesis of whisky lactone isomers catalyzed by bacteria in the genus Rhodococcus

Whisky lactone is a naturally occurring fragrance compound in oak wood and is widely used as a sensory additive in food products. However, safe and efficient methods for the production of its individual enantiomers for applications in the food industry are lacking. The aim of this study was to develop an efficient and highly stereoselective process for the synthesis of individual enanti omeric forms of whisky lactones. The proposed three-step method involves (1) column chromatography separation of a diastereo isomeric mixture of whisky lactone, (2) chemical reduction of cis-and trans -whisky lactones to corresponding syn-and anti -diols, and (3) microbial oxidation of racemic diols to individual enantiomers of whisky lactone. Among various bacteria in the genera Dietzia , Gordonia , Micrococcus , Rhodococcus, and Streptomyces , R. erythropolis DSM44534 and R. erythropolis PCM2150 effectively oxidized anti-and syn -3-methyl-octane-1,4-diols (1a-b) to corresponding enantiomerically pure cis-and trans -whisky lactones, indicating high alcohol dehydrogenase activity. Bio-oxidation catalyzed by whole cells of these strains yielded enantiom erically pure isomers of trans -(+)-(4S ,5R ) (2a), trans -(-)-(4R ,5S ) (2b), and cis -(+)-(4R ,5R ) (2d) whisky lactones. The optical density of bacterial cultures and the impact of the use of acetone powders as catalysts on the course of the reaction were also evaluated. Finally, the application of R. erythropolis DSM44534 in the form of an acetone powder generated the enantiom erically enriched cis -(-)-(4S ,5S )- isomer (2c) from the corresponding syn -diol (1b). The newly developed method provides an improved approach for the synthesis of chiral whisky lactones

A Virtual Classroom Via Dataconferencing: A Multi-Institutional Experience

This paper presents the experience of five faculty from four universities who are co-developing and team teaching courses using the world-wide web (WWW). In particular two novel power engineering courses, Flexible Control of Transmission Systems and Flexible Control of Distribuction Systems, introduce the student to the application of power electronic-based controllers, known specifically as flexible AC transmission systems (FACTS) controllers, to enhance the performance of the transmission and distribution systems in an electric power system. In order to leverage faculty expertise in the various topics included in each course, a unique partnership was formed among five faculty from the following universities: University of Arkansas, Kansas State University, University of Missouri--Rolla and Purdue University. In order to achieve the most effective presentation, in the presence of geographical, cost, time and technology constraints, the co-developers decided to pursue various distance learning strategies to link the four universities together in a live interactive virtual classroom utilizing dataconferencing software and the WWW. In this paper we address the trials and tribulations of our experience. In particular, we discuss the use of video tape technology by mail, the use of live audio and video via an integrated service digital network (ISDN) approach, and lastly, dataconferencing software in conjunction with telephone conferencing. Each of these alternative methodologies are examined in detail and are compared and contrasted from a cost and pedagogical point of view based on our experience

Collaborative Distance Education in Power Engineering

This paper presents a perspective on offering shared-courses, or courses simultaneously offered at two or more universities via various distance educational frameworks. Over a three year duration, two senior/graduate level courses were jointly developed and offered to the students at the University of Missouri--Rolla, the University of Arkansas, Kansas State University, and Purdue University. This paper discusses the various distance educational technologies including two-way audio/visual via ISDN line, video-tapes, and web-based conferencing. Both instructor and student reactions to these mediums are included. Pedagogical methods appropriate for these mediums are outlined. The paper concludes with recommendations and strategies for engineering institutions who would like to course-share with other universities and industry

A Multi-Institutional Cooperative Approach to Power Engineering Education

This paper describes the multi-institutional cooperative effort between the University of Missouri--Rolla, Kansas State University, and the University of Arkansas to develop two new courses in flexible power system control

Integrating Research Results into a Power Engineering Curriculum

This paper presents summaries of the activities of six research active power engineering educators which were presented in a panel session of the same name at the IEEE Power Engineering Society Winter Meeting on February 3, 1997 in New York City, USA. Each of the panelists discusses how research results are incorporated into courses and how students benefit from this approach

Stability of the nonlinear dynamics of an optically injected VCSEL

Automated protocols have been developed to characterize time series data in terms of stability. These techniques are applied to the output power time series of an optically injected vertical cavity surface emitting laser (VCSEL) subject to varying injection strength and optical frequency detuning between master and slave lasers. Dynamic maps, generated from high resolution, computer controlled experiments, identify regions of dynamic instability in the parameter space. © 2012 Optical Society of America

Dental evidence for ontogenetic differences between modern humans and Neanderthals

Humans have an unusual life history, with an early weaning age, long childhood, late first reproduction, short interbirth intervals, and long lifespan. In contrast, great apes wean later, reproduce earlier, and have longer intervals between births. Despite 80 y of speculation, the origins of these developmental patterns in Homo sapiens remain unknown. Because they record daily growth during formation, teeth provide important insights, revealing that australopithecines and early Homo had more rapid ontogenies than recent humans. Dental development in later Homo species has been intensely debated, most notably the issue of whether Neanderthals and H. sapiens differ. Here we apply synchrotron virtual histology to a geographically and temporally diverse sample of Middle Paleolithic juveniles, including Neanderthals, to assess tooth formation and calculate age at death from dental microstructure. We find that most Neanderthal tooth crowns grew more rapidly than modern human teeth, resulting in significantly faster dental maturation. In contrast, Middle Paleolithic H. sapiens juveniles show greater similarity to recent humans. These findings are consistent with recent cranial and molecular evidence for subtle developmental differences between Neanderthals and H. sapiens. When compared with earlier hominin taxa, both Neanderthals and H. sapiens have extended the duration of dental development. This period of dental immaturity is particularly prolonged in modern humans.Human Evolutionary Biolog

Contrasting crystal packing arrangements in triiodide salts of radical cations of chiral bis(pyrrolo[3,4-d])tetrathiafulvalenes

Crystal structures of six 1 : 1 triiodide salts of a series of enantiopure bis(pyrrolo[3,4-d])TTF derivatives, the first structures of radical cation salts reported for this bis(pyrrolo) donor system, show three different arrangements of triiodide ions, organised either in head-to-tail pairs, in infinite lines, or in a castellated arrangement. The complex crystal structures, obtained by electrocrystallisation, are influenced by the presence of solvent, for example changing an ABCABC packing arrangement to ABAB with inclusion of THF, as well as by the size of the chiral side chain

Deterministic polarization chaos from a laser diode

Fifty years after the invention of the laser diode and fourty years after the report of the butterfly effect - i.e. the unpredictability of deterministic chaos, it is said that a laser diode behaves like a damped nonlinear oscillator. Hence no chaos can be generated unless with additional forcing or parameter modulation. Here we report the first counter-example of a free-running laser diode generating chaos. The underlying physics is a nonlinear coupling between two elliptically polarized modes in a vertical-cavity surface-emitting laser. We identify chaos in experimental time-series and show theoretically the bifurcations leading to single- and double-scroll attractors with characteristics similar to Lorenz chaos. The reported polarization chaos resembles at first sight a noise-driven mode hopping but shows opposite statistical properties. Our findings open up new research areas that combine the high speed performances of microcavity lasers with controllable and integrated sources of optical chaos.Comment: 13 pages, 5 figure

In vitro antileukemic activity of novel adenosine derivatives bearing boron cluster modification

A series of adenosine derivatives bearing a boron cluster were synthesized and evaluated for their cytotoxicity against primary peripheral mononuclear cells from the blood of 17 patients with leukemias (16 CLL and 1 very rare PLL), as well as from 5 healthy donors used as a control. Among the tested agents, two, i.e., compounds 1 and 2, displayed high in vitro cytotoxicity and proapoptotic potential on leukemic cells, with only scarce activity being seen against control cells. Biological tests related to apoptosis revealed the activation of the main execution apoptotic enzyme, procaspase-3, in CLL and PLL cells exposed to compounds 1 and 2. Moreover, the above compounds indicated high activity in the proteolysis of the apoptotic markers PARP-1 and lamin B1, fragmentation of DNA, and the induction of some changes in the expression of the Mcl-1, protein apoptosis regulator in comparison with control cells