2,271 research outputs found
Controlling Factors Determining The Selective Hscn Addition To Double Bonds And Their Application To The Synthesis Of 7-isothiocyano-7,8-α-dihydro-bisabolene
The reactivity of terminal and trisubstituted double bonds of monoterpenes with HSCN has been examined by GC giving evidence that kinetics is responsible for the chemoselective addition to terminal double bonds in terpenes. The results show that the addition to the terminal double bond is about 17 times faster than for trisubstituted double bonds and that the presence of the first SCN group in the molecule prevents a second addition. The presence of a hydroxyl or methoxy group in the molecule, decreases the reaction kinetics. Based on these kinetic experiments a two steps synthesis of the natural product 7-isothiocyano-7,8-dihydro-α-bisabolene using bisabolol as starting material, was planned and successfully accomplished.125661666Drobnica, L., KristĂan, P., AugustĂn, J., The Chemistry of the Cyanates and Their Thio Derivatives, , Saul Patai Ed., John Wiley & Sons, New YorkEdenborough, M.S., Herbert, R.B., (1988) Nat. Prod., p. 229Faulkner, D.J., (1994) Nat. Prod., p. 355(1993) Nat. Prod., p. 497(1992) Nat. Prod., p. 323(1991) Nat. Prod., p. 97(1990) Nat. Prod., p. 269(1988) Nat. Prod., p. 613Fraga, B.M., (1994) Nat. Prod. Rep., p. 533Piers, E., Young, B.W.A., Rettig, S.J., (1987) Tetrahedron, 43 (23), p. 5521Piers, E., Yeung, B.W., (1986) Can. J. Chem., 64, p. 2475Chenera, B., Chuang, C.P., Hart, D.J., Lai, C.S., (1992) J. Org. Chem., 57, p. 2018Da Silva, C.C., Almagro, V., Zukerman-Schpector, J., Castellano, E.E., Marsaioli, A.J., (1994) J. Org. Chem., 59, p. 2880Da Silva, C.C., Almagro, V., Marsaioli, A.J., (1993) Tetrahedron Lett., 34, p. 6717Martin, V.S., Woodward, S.S., Katsuki, T., Yamada, Y., Ikeda, M., Sharpless, K.B., (1981) J. Am. Chem. Soc., 103, p. 6237Rakels, J.L., Straathof, A.J.J., Heijnin, J.J., (1993) Enzyme Microb. Technol, 15, p. 1051Diveley, W.R., Buntin, G.A., (1969) J. Org. Chem., 34, p. 616Queiroga, C.L., Ferracini, V.L., Marsaioli, A.J., (1996) Phytochemistry, 42, p. 1097(-)Bisabolol (8) [(αS, 1S)-1-methanol-α,4-dimethyl-α-4-methyl-3-pentenyl-3-cyclohexene] was obtained from commercial candeia oil (CITRĂ“LEO - S.Paulo, SP, Brazil)Sullivan, B.W., Faulkner, D.J., Okamoto, K.T., Chen, M.H.M., Clardy, J., (1986) J. Org. Chem., 51, p. 5134Dubois, J.E., Lomas, J.S., (1971) Tetrahedron Lett., 7, p. 599Delay, F., Ohloff, F., (1979) Helv. Chem. Acta, 62, p. 326A sample of dihydrolimonene was kindly provided by Prof. Marcio C. S. de Mattos from IQ/UFRJ, RJ, Brazi
InfluĂŞncia das culturas láticas no Ăndice de proteĂłlise do queijo minas frescal
Estudou-se, a influĂŞncia de culturas láticas no Ăndice de proteĂłlise do queijo Minas Frescal, processado com leite nĂŁo pasteurizado e pasteurizado. O emprego de culturas láticas na elaboração de queijo Minas Frescal pode ser indicado, uma vez que o Ăndice de proteĂłlise sĂł se correlacionou com o tempo de conservação.The influence of lactic cultures in the ripening index of Minas Frescal cheese was studied, utilizing pasteurized and not pasteurized milk. The use of lactic cultures for Minas Frescal cheese can be recomended, since the ripening index had good correlation only with storage time
Relationships between head-out aquatic exercise kinematics and musical cadence: analysis of the side kick
Background: Head-out aquatic exercises became one of the most popular physical activities within the health primarily and thirdly prevention system. Music is seen as one of the most important aspects when conducting head-out aquatic exercise sessions. Research question: Is there any relationship between musical cadence and the kinematic behaviour when performing aerobic head-out aquatic exercises? It was hypothesized that an increase in music cadence will would impose a decrease of the segment range of motion. Type of study: Experimental, prospective. Methods: Six young and clinically healthy women with at least one year of experience conducting head-out aquatic classes were videotaped in the frontal plane, with a pair of cameras providing a double projection (above and below the water surface). Subjects performed an incremental protocol of five bouts (120b.min-1, 135b.min-1, 150b.min-1, 165b.min-1 and 180b.min-1) with 16 full cycles of the “side kick” exercise. Data processing and calculation of segmental (i.e. hands and feet) and anatomical landmark (i.e. centre of mass) were performed using the software Ariel Performance Analysis System and applying the DLT algorithm. Results: There was a decrease in the cycle period during the incremental protocol. The relationships between the segmental lateral and vertical displacements with the musical cadence were not significant. The segmental velocities on the lateral and vertical components showed significant increases throughout the incremental protocol. Conclusions: The data suggest that segmental velocity increases with increasing cadence, reducing the cycle period and maintaining the segmental displacements
Head-out aquatic exercise “sailor’s jigs” kinematics at increasing musical cadence
The aim of this study was to analyze the relationships between “Sailor’s jigs” kinematic and increasing music cadence. Six young women with at least one year of experience conducting this type of head-out aquatic programs, with no kind of skeletal muscle injury reported on the last six months and non-pregnant were evaluated. The exercise was recorded on video, in the frontal plane, using a pair of cameras, enabling a double projection, from above and underwater body motions, at five increasing cadences (120 b.min-1, 135 b.min-1, 150 b.min-1, 165 b.min-1 and 180 b.min-1). Images were thereafter digitized in specific software (Ariel Performance Analysis Systems). The cycle period decreased through the incremental protocol. Cycle period decrease is done decreasing joints range of motion and increasing the limbs segmental velocity as well. Although these combined kinematical strategy, a deeper analysis reveals that subjects decrease the cycle period mainly decreasing the range of motions
Head-out aquatic exercise “sailer’s jigs” kinematics at increasing musical cadence
The aim of this study was to analyze the relationships between
“Sailor’s jigs” kinematics and increasing music cadence. Six young
women, non-pregnant, with at least one year of experience conducting
this type of head-out aquatic program, with no kind of skeletal
muscle injury reported in the last six months were evaluated. The
exercise was recorded on video, in the frontal plane, using a pair of
cameras, enabling a double projection, from above and underwater
body motions, at five increasing cadences (120 b.min-1, 135 b.min-1,
150 b.min-1, 165 b.min-1 and 180 b.min-1). Images were thereafter
digitized in specific software (Ariel Performance Analysis Systems).
The cycle period decreased through the incremental protocol. Cycle
period decrease is done decreasing joint range of motion and increasing
the limbs segmental velocity as well. Although these combined
kinematical strategy, a deeper analysis reveals that subjects decrease
the cycle period mainly decreasing the range of motion
Nonintegrable Interaction of Ion-Acoustic and Electromagnetic Waves in a Plasma
In this paper we re-examine the one-dimensional interaction of
electromagnetic and ion acoustic waves in a plasma. Our model is similar to one
solved by Rao et al. (Phys. Fluids, vol. 26, 2488 (1983)) under a number of
analytical approximations. Here we perform a numerical investigation to examine
the stability of the model. We find that for slightly over dense plasmas, the
propagation of stable solitary modes can occur in an adiabatic regime where the
ion acoustic electric field potential is enslaved to the electromagnetic field
of a laser. But if the laser intensity or plasma density increases or the laser
frequency decreases, the adiabatic regime loses stability via a transition to
chaos. New asymptotic states are attained when the adiabatic regime no longer
exists. In these new states, the plasma becomes rarefied, and the laser field
tends to behave like a vacuum field.Comment: 19 pages, REVTeX, 6 ps figures, accepted for publication in Phys.
Rev.
Normative data of the start in the 50 m events at the 2021 LEN European Championships and understanding its relationship with the final race
This study aimed to: (i) present normative data of the variables related to the start in
the four swim strokes by tier and sex, and; (ii) understand the relationship between the 15th
meter mark time and the final race time of the male and female swimmers competing in the four
50 m events at the 2021 European Championships. Participants were all male and female
swimmers who competed in the 50 m events at the 2021 LEN European Championships held in
Budapest. The official race times and block times were retrieved from the official competition
website. All starting variables were analyzed in a dedicated software for race analysis. The 15th
meter mark time was used as the start main outcome. For all events by sex, the 15th meter mark
time was the variable presenting the highest and largest tier effect (p < 0.001) besides the final
race time. Overall, despite the swim stroke, the variables related to the underwater phase were
also responsible for the significant tier effect (p < 0.001). The 15th meter mark time presented a
high to very-high relationship with the final race time in all four swim strokes. This relationship
was stronger in freestyle (both sexes). That is, swimmers who achieve the 15th meter mark sooner
are more likely to deliver better performances. Coaches must be aware that the underwater
phase plays a key-role on the swimmers’ (both sexes) start performance. Nonetheless, different
strategies can be used based on the swimmers’ strength and weaknesses. Moreover, the start
performance in all four swim strokes and in both sexes can strongly predict the final race time.This research was supported by national funds (FCT - Portuguese Foundation for Science
and Technology) under the project UIDB/DTP/04045/2020info:eu-repo/semantics/publishedVersio
Kinematical characterisation of a basic head-out aquatic Exercise during an incremental protocol
The aim of this study was to analyze the relationships between musical cadence and kinematical characteristics of a basic head-out aquatic exercise. Six young women with at least one year of experience conducting head-out aquatic classes were videotaped in the sagital plane with a pair of cameras providing a dual projection from both above and underwater performing 5 incremental bouts (120, 135, 150, 165 and 180 b.min-1) of the basic head-out aquatic exercise “rocking horse”. There was a decrease of the cycle period throughout the protocol. Relationships between horizontal or vertical displacements with music cadence were not significant. Increased cadence imposed increased segmental and centre of mass’ velocities. As a conclusion expert and fit subjects seem to increase segmental velocity with increasing musical cadence
Kinematical characterization of the basic head-out aquatic exercise “Sailor’s Jigs”
Massive research has been produced
throughout the last decades in order to
be@er understand the role of head-out
aquatic exercises in populations’ health
(Barbosa et al, 2009). Indeed, such studies
aimed to characterize the physiological
acute and/or chronic response of subjects
performing head-out aquatic exercises.
Moreover, the comprehensive knowledge
about the biomechanical (i.e. kinematical)
behavior performing this aquatic actvity is
quite reduced.info:eu-repo/semantics/publishedVersio
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