Bounds on Codes Derived by Counting Components in Varshamov Graphs

We are interested in improving the Varshamov bound for finite values of length n and minimum distance d. We employ a counting lemma to this end which we find particularly useful in relation to Varshamov graphs. Since a Varshamov graph consists of components corresponding to low weight vectors in the cosets of a code it is a useful tool when trying to improve the estimates involved in the Varshamov bound. We consider how the graph can be iteratively constructed and using our observations are able to achieve a reduction in the over-counting which occurs. This tightens the lower bound for any choice of parameters n, k, d or q and is not dependent on information such as the weight distribution of a code. This work is taken from the author’s thesis [10]     

Three-component one-pot total syntheses of glyantrypine, fumiquinazoline F, and fiscalin B promoted by microwave irradiation

A microwave-promoted three-component one-pot reaction has been developed to provide access to the core pyrazino[2,1-b]quinazoline-3,6-dione (1) scaffold, which is common to several families of alkaloids with significant biological activities. By adapting this synthetic strategy through the use of selected Boc-amino acids and amino acid esters, we have accomplished highly efficient and concise total syntheses of glyantrypine (2), fumiquinazoline F (3), and fiscalin B (5), achieving overall yields of 55, 39, and 20%, respectively.     

Microwaves and cellular immunity. II. Immunostimulating effects of microwaves and naturally occurring antioxidant nutrients

The effect of 8.15-18 GHz (1 Hz within) microwave radiation at a power density of 1 microW/cm2 on the tumor necrosis factor (TNF) production and immune response was tested. A single 5 h whole-body exposure induced a significant increase in TNF production in peritoneal macrophages and splenic T cells. The mitogenic response in T lymphocytes increased after microwave exposure. The activation of cellular immunity was observed within 3 days after exposure. The diet containing lipid-soluble nutrients (beta-carotene, alpha-tocopherol and ubiquinone Q9) increased the activity of macrophages and T cells from irradiated mice. These results demonstrate that irradiation with low-power density microwaves stimulates the immune potential of macrophages and T cells, and the antioxidant treatment enhances the effect of microwaves, in particular at later terms, when the effect of irradiation is reduced.     

The boron-mediated ketone-ketone aldol reaction

The first examples of the directed, boron-mediated aldol reaction between different ketones are presented. Transformation of a variety of ketones to their corresponding boron enolates with Chx₂BCl/Et₃N, followed by reaction with acceptor ketones in diethyl ether, and oxidation of the resultant boron aldolate (H₂O₂, MeOH/pH 7 buffer), provided the aldol addition products. The reaction was most facile when cyclic ketones were used, with the highest yields obtained for the reaction of boron enolates with cyclohexanone as the acceptor.     

Heterogeneous catalysts for cyclic carbonate synthesis from carbon dioxide and epoxides

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Sustainable,mild and efficient p-methoxybenzyl ether deprotections utilizing catalytic DDQ

A procedure for the selective deprotection of p-methoxybenzyl ethers using catalytic amounts of DDQ and of sodium nitrite, with oxygen as the terminal oxidant, is reported.     

Batch versus Flow Photochemistry: A Revealing Comparison of Yield and Productivity

The use of flow photochemistry and its apparent superiority over batch has been reported by a number of groups in recent years. To rigorously determine whether flow does indeed have an advantage over batch, a broad range of synthetic photochemical transformations were optimized in both reactor modes and their yields and productivities compared. Surprisingly, yields were essentially identical in all comparative cases. Even more revealing was the observation that the productivity of flow reactors varied very little to that of their batch counterparts when the key reaction parameters were matched. Those with a single layer of fluorinated ethylene propylene (FEP) had an average productivity 20 % lower than that of batch, whereas three‐layer reactors were 20 % more productive. Finally, the utility of flow chemistry was demonstrated in the scale‐up of the ring‐opening reaction of a potentially explosive [1.1.1] propellane with butane‐2,3‐dione.     

Morphological regimes of poly(ε-caprolactone)/octaisobutyl polyhedral oligosilsesquioxane composite films in relation to film composition and thickness

The morphological evolution of poly(ε-caprolactone) (PCL)/octaisobutyl polyhedral oligomeric silsesquioxane (IBUPOSS) films was analyzed using scanning electron microscopy (SEM) and polarized optical microscopy (POM). The morphologies of the blend films with PCL/IBUPOSS mass ratios of 95:5 to 50:50 were discussed according to decomposition mechanism in relation to film composition and thickness. In addition to the morphological regime for films with lower IBUPOSS loadings, in which the growth of PCL spherulites was nearly independent on the presence of fine IBUPOSS aggregates, two new morphological regimes were observed for the films with higher IBUPOSS loadings: (1) thicker blend films exhibited a rich dynamics, giving rise to a trilayer structure and (2) the decomposition of thinner films was induced by the kinetically controlled growth of IBUPOSS aggregates. By varying the thickness and the composition of the blend films, the current study provides important new insight into the rich phase behavior of nanoparticle-filled polymer films.