Photochemical dehydrogenation, ring contraction, and ring expansion of hydrogenated derivatives of benzoxazino-benzoxazine, quinoxalino-quinoxaline, and bibenzothiazole.

The photochemical properties of the title compounds have been investigated and compared. The benzoxazino-benzoxazine derivatives 1 are photochemically converted into hydrogenated oxazole derivatives. In some cases this ring contraction is accompanied by a dehydrogenation reaction whereby the heterocyclic ring system becomes aromatic. Hydrogenated quinoxalino-quinoxalines also undergo a photodehydrogenation reaction and become aromatic. However, a ring contraction yielding the imidazolyl system does not take place. The only investigated sulfur-containing analog has different properties. The stable form is the bibenzothiazole 23 which contains a five-membered heterocyclic ring system. Photochemically 23 rearranges under ring expansion to give the benzothiazino-benzothiazine 24

U.S. Dairy Farm Cost Efficiency

WP 2005-12 June 2005A stochastic cost efficiency equation was estimated for the U.S. dairy industry using national data from the production year 2000. The cost of producing a unit of milk was estimated into separate frontier and efficiency components, with both components estimated as a function of causation variables. Variables that might influence the cost of production and cost efficiency of an individual dairy farm were entered as impacting the frontier component as well as the efficiency component of the stochastic curve since a prior both components could be impacted. The factor that has the greatest impact on the cost curve frontier is the number of hours a day the milking facility is used. Using the milking facility more hours per day decreased frontier costs. However, inefficiency increased with increased hours of milking facility use, such that there was no net reduction in costs. Thus farmers can decrease costs with increased utilization of the milking facility, but only if they are efficient in this strategy. Age increased cost of production since older farmers were less efficient. Parlors used for milking as compared to stanchion milking did not decrease frontier costs, but did decrease costs because of increased efficiency, as did the use of a feed nutritionist. Use of rotational grazing decreased frontier costs but also increased fixed cost inefficiency, with a net reduction in cost of production per cwt. of milk sold.Funding for this research was provided by the USDA, National Research Initiative Competitive Program, Markets and Trade Project 2002-01488

Towards a consistent mechanism of emulsion polymerization—new experimental details

The application of atypical experimental methods such as conductivity measurements, optical microscopy, and nonstirred polymerizations to investigations of the ‘classical’ batch ab initio emulsion polymerization of styrene revealed astonishing facts. The most important result is the discovery of spontaneous emulsification leading to monomer droplets even in the quiescent styrene in water system. These monomer droplets with a size between a few and some hundreds of nanometers, which are formed by spontaneous emulsification as soon as styrene and water are brought into contact, have a strong influence on the particle nucleation, the particle morphology, and the swelling of the particles. Experimental results confirm that micelles of low-molecular-weight surfactants are not a major locus of particle nucleation. Brownian dynamics simulations show that the capture of matter by the particles strongly depends on the polymer volume fraction and the size of the captured species (primary free radicals, oligomers, single monomer molecules, or clusters)

Swelling of latex particles—towards a solution of the riddle

The assumption that during emulsion polymerization, the monomer molecules simply diffuse through the aqueous phase into the latex particles is a commonplace. However, there are experimental hints that this might not be that easy. Here, simulation results are discussed based on Fick’s diffusion laws regarding the swelling of latex particles. The results of quantitative application of these laws for swelling of latex particles allow the conclusion that the instantaneous replenishment of the consumed monomer during emulsion polymerization requires a close contact between the monomer and the polymer particles

Process for the modification of polymers, in particular polymer nanoparticles

The present invention relates to a highly efficient and ultra fast process for the photo-initiated preparation of polymers by polymerization using photoinitiators comprising a phosphorous oxide or -sulfide group and modification of said polymers. In particular the invention relates to an ultra fast process for the photo-initiated preparation of latices comprising polymer nanoparticles by heterophase polymerization using photoinitiators comprising a phosphorous oxide or -sulfide group and their modification. In another aspect, the invention relates to polymers and polymer nanoparticles obtainable by said process