No abstract

No abstract

The metabolism of organic molecules by living organisms is of fundamental interest to biologists, microbiologists, and biochemists. The primary avenue of metabolism in most living organisms is via oxidative pathways. The aromatic hydrocarbons (arenes) are subject to such oxidative degradation; their mammalian and microbial systems have been extensively studied. It is the capacity of certain microorganisms to convert by oxidation arenes into arene cis ‐dihydrodiols that provide the foundation of this chapter. Arenes are subject to a variety of oxidations, but the expression “microbial arene oxidation” is used for the specific oxidation discussed here. The assignment of dihydrodiol configuration and the use of mutant strains of microorganisms laid the groundwork for the development of arene oxidation as a process useful to organic synthesis. Other advances discussed in this chapter led to the development of microbial arene oxidations that are suitable for organic synthesis. Attractive features include: the process is one of a very few that disrupts the aromatic system of arenes; the array of functional groups generated in the dihydrodiol products is useful; the process is highly enantioselective, affording pure enantiomerically pure products in most cases. For this chapter, the literature has been reviewed through 2001.

This study was developed to empirically determine the impact of the following variables on the speeds of skiers and snowboarders: activity [skiing versus snowboarding], visibility [clear and sunny sky versus cloudy, overcast conditions], type of resort [day, destination, or combination], and helmets [use or not of helmet]. The study also evaluated differences in speed between males and females and the ability of subjects to estimate their speed. The authors measured the speed of some 650 individuals at three different ski resorts in the U.S. during the winter of 2002/2003. One resort was primarily a destination resort in Utah, one was a day area in New York, and the third resort in Vermont had a combination of destination and day skiers. The speeds were determined by means of a calibrated radar speed gun. Speeds were gathered on consecutive skiers and snowboarders as they were observed from an uphill, looking downhill position. The speed recorded was the highest speed observed during a several second interval while the observed person went through several turns as the skiers and snowboarders moved away from the observer. All observations were made on wide, straight, well-groomed ‘blue square’ (more difficult) trails. The slopes ranged from 16–20° in steepness. The average speed for all observations was 43.0 km/h (26.7 mph), with a standard deviation of 11.2 km/h (7.0 mph). The average speed for skiers of 44.5 km/h (27.6 mph) was significantly higher than that for snowboarders at 38.9 km/h (24.1 mph). The average speed under good visibility of 46.7 km/h (29.0 mph) was significantly higher than for poor visibility conditions at 38.3 km/h (23.7 mph). The average speed for helmet users of 45.8 km/h (28.4 mph) was significantly higher than those not using a helmet at 41.0 km/h (25.4 mph). Males ski and snowboard significantly faster than females. Skiers and snowboarders are fair at estimating their speed (r = 0.56), but they tend to underestimate their speeds the faster they go; for example, at an actual 48 km/h (30 mph), they estimate that they are traveling at 37 km/h (23 mph). The observed speeds are well above the speeds (22.6 km/h, or 14.0 mph) used for ASTM F 2040 helmet testing protocols for recreational snow sports helmets.

Although Vibrio cholerae O139 synonym Bengal strains, from the current epidemics in India and Bangladesh, are closely related to seventh-pandemic strains, as shown by multilocus enzyme electrophoresis, Bengal strains are encapsulated and portions of the O1 antigen biosynthetic complex genes found in O1 strains are altered or lacking. Encapsulated Bengal strains showed resistance to killing by normal human serum. The presence of the capsule suggests the potential for bloodstream invasion in susceptible hosts and has profound implications for vaccine development.

No abstract

Using a mortar and pestle and working in a glove bag under an atmosphere of dry nitrogen, lumps of potassium superoxide, purchased from K & K Chemicals, were ground to a fine consistency before use. (9) G.

The synthesis of 2,8-dimethyl-6H,12H-5,11-methanodibenzo[b,f][1,5]diazocine (Tröger's base) from p-toluidine and of two Tröger's base analogs from other anilines by reaction with hexamethylenetetramine in trifluoroacetic acid is described. 2,3,6,7-Tetrahydro-9-methyl-2,6-di-p-tolyl-1H,5H-pyrimido[5,6,1-ij] quinazoline is formed as a secondary product in the reaction of p-toluidine and hexamethylenetetramine. One of the Tröger's base analogs, 2,8-bis(3'-pyridylmethyl)-6H,12H-5,11-methanodibenzo[b,f][1,5]d iazocine (5), is an effective inhibitor of the enzyme, thromboxane A2 (TxA2) synthase, with an ED50 of 30 ng/mL in a specified in vitro assay. Three analogs having substituents on the bridging methylene group of the bicyclic nucleus of the Tröger's base structure were prepared, but all were considerably less active than the aforementioned compound in the inhibition assay. The structures of these inhibitors of TxA2 synthase fall outside the classical structure-activity relationship that has been established for this class of enzyme inhibitors.