Classroom Innovation: Games to Make Chemistry More Interesting and Fun

Many students of agronomy engineering, who are required to take organic chemistry, find the class unpleasant and uninteresting because they feel forced to learn concepts that they regard as irrelevant to their career plans. When this lack of motivation is combined with limited self-discipline, students dont study and, thus, fail to learn the subject. This paper presents a method of adapting the course materials and methodology to the students needs by the inclusion of appropriate games. These games help to create a less formal atmosphere and add variety to the class, and they can even be used as methods of evaluation. Students exposed to this method are more apt to experiment and participate freely in class.     

Zur Chemie von Polyhalocyclopentadienen, 22. Mitt.: Über die Herstellung von 1,4,5,6,7,7-Hexachlorbicyclo[2.2.1]hepten-(5)-bishydroxymethylen-(2,3)

Zusammenfassung 1,4,5,6,7,7-Hexachlor-bicyclo[2.2.1]hepten-(5)-bis-hydroxymethylen-(2,3) (I) läßt sich sowohl durch direkte Umsetzung von Hexachlorcyclopentadien (II) und Buten-(2)-diol-(1,4) (III) wie auch durch LiAlH₄-Reduktion von 1,4,5,6,7,7-Hexachlor-bicyclo[2.2.1]hepten-(5)-dicarbonsäure-(2,3) (IV), IV-Anhydrid oder IV-Estern in guter Ausbeute gewinnen.Auf Wunsch der Autoren erscheint diese Abhandlung erst im Herbst 1961.21. Mitt., Dtsch. Bund. Pat. 1 081 886 vom 2. 5. 1958.     

Detecting synchronizations in an asymmetric vocal fold model from time series data

A nonlinear modeling approach is presented for the reconstruction of the synchronization structure in an asymmetric two-mass model from time series data. The asymmetric two-mass model describes a variety of normal and pathological human voices associated with synchronous and desynchronous oscillations of the two asymmetric vocal folds. Our technique recovers the synchronization diagram, which yields the regimes of synchronization as well as desynchronization, which are dependent upon the asymmetry parameter and the subglottal pressure. This allows the prediction of the regime of pathological phonation associated with desynchronization of the vocal folds from a few sets of recorded time series. It is shown that the modeling is quite effective when the time series data are chaotic and if they are taken from a regime of desynchronization. We discuss the applicability of the present approach as a diagnostic tool for voice pathologies.     

Plexin B3 promotes neurite outgrowth,interacts homophilically,and interacts with Rin

Background  

Plexins, known to date as receptors of semaphorins, are implicated in semaphorin-mediated axon repulsion and growth cone collapse. However, subtype-specific functions of the majority of the nine members of the mammalian plexin family are largely unknown. In order to investigate functional properties of B-plexins, we analyzed the expression of human and murine plexin B3 and expressed full-length human plexins B2 (B2) and B3 (B3) in NIH-3T3 cells.     

Comparison of measurements of phase velocity in human calcaneus to Biot theory

Biot's theory for elastic propagation in porous media has previously been shown to be useful for modeling the dependence of phase velocity on porosity in bovine cancellous bone in vitro. In the present study, Biot's theory is applied to measurements of porosity-dependent phase velocity in 53 human calcanea in vitro. Porosity was measured using microcomputed tomography for some samples (n = 23) and estimated based on bone mineral densitometry for the remaining samples (n = 30). The phase velocity at 500 kHz was measured in a water tank using a through-transmission technique. Biot's theory performed well for the prediction of the dependence of sound speed on porosity. The trend was quasilinear, but both the theory and experiment show similar slight curvature. The root mean square error (RMSE) of predicted versus measured sound speed was 15.8 m/s.     

Water dimer diffusion on Pd[111] assisted by an H-bond donor-acceptor tunneling exchange

Based on the results of density functional theory calculations, a novel mechanism for the diffusion of water dimers on metal surfaces is proposed, which relies on the ability of H bonds to rearrange through quantum tunneling. The mechanism involves quasifree rotation of the dimer and exchange of H-bond donor and acceptor molecules. At appropriate temperatures, water dimers diffuse more rapidly than water monomers, thus providing a physical explanation for the experimentally measured high diffusivity of water dimers on Pd[111] [Science 297, 1850 (2002)]].