On sums of independent random variables whose distributions belong to the max domain of attraction of max stable laws

In this article we study the max domains of attraction of distributions of sums of independent random variables belonging to the max domains of attraction of max stable laws under linear normalization. These results lead to the study of the max domains of attraction of distributions of products of independent random variables belonging to the max domain of attraction of max stable laws under power normalization

Crystal engineering principles applied to solution photochemistry: controlling the photodimerization of stilbazolium salts within γ-cyclodextrin and cucurbit[8]uril in water

Borrowing concepts from crystal engineering techniques we have been able to steer the photodimerization of stilbazolium salts included in γ-cyclodextrin towards a desired dimer

Time dependent expression of cytokines in Mycobacterium bovis infected cattle lymph nodes

Original article can be found at: http://www.sciencedirect.com/ Copyright Elsevier [Full text of this article is not available in the UHRA]Advancements in the current diagnostic and vaccination protocols employed against bovine tuberculosis rely heavily upon a sound knowledge of the bovine immunological response. Central to this is the importance of timing in the cellular immune profile and how this dynamic process evolves post-Mycobacterium bovis challenge. In the present study, we quantitatively analysed mRNA expression of interferon gamma (IFN-γ), tumour necrosis factor alpha (TNF-α) and interleukins (IL) 4 and 10 within select thoracic lymph nodes of cattle infected with M. bovis for 5, 12 and 19 weeks as compared to non-infected bovine tissues. The M. bovis infected lymph nodes displayed significantly higher expression levels of IFN-γ and TNF-α as compared to the non-infected lymph node tissues. This, in conjunction with undetectable levels of IL4, suggests a pro-inflammatory cytokine response. However a significant increase was also detected in IL10 mRNA which is consistent with a described aspect of TH1 type T cells in Leishmania infection, a ‘self-limiting’ process in which cells produced both IFN-γ and IL10 with the aim of controlling the heightened immunopathological responses. This was further reflected when comparing the cytokine profiles of the individual lymph node types, as those displaying a higher IFN-γ/IL10 ratio also had a greater level of gross pathology. This data highlights the important role of IL10 in the bovine response to M. bovis infection and supports its involvement as an immunological marker of disease progression.Peer reviewe

Preorientation of olefins toward a single photodimer: cucurbituril-mediated photodimerization of protonated azastilbenes in water

With the view to establishing the generality of cucurbit[8]uril as a template, the photodimerization of hydrochloride salts of eight azastilbenes has been investigated in an aqueous medium. Whereas in solution upon excitation all of these olefins yield products of geometric isomerization, cyclization, and hydration, in the presence of cucurbit[8]uril the predominant product is that of dimerization. Such a change in product distribution is attributed to the localization of the olefins by the host cucurbit[8]uril. Most importantly, instead of a mixture of dimers, predominantly a single dimer was obtained in each case. The nature of the dimer that was formed could be rationalized on the basis of the principles of "best fit" and "minimization of electrostatic repulsion". The superior ability of cucurbit[8]uril compared to micelles to act as a templating agent is attributed to its ability to provide a reaction cavity that is tight and time-independent

Role of free space and conformational control on photoproduct selectivity of optically pure α-alkyldeoxybenzoins within a water-soluble organic capsule

Optically pure α-alkyl deoxybenzoins resulting in products of Norrish Type I and Type II reactions upon excitation has been investigated within the octa acid (OA) capsule in water. The product distribution was different from that in an organic solvent and was also dependent on the length of the α-alkyl chain. Most importantly, a rearrangement product not formed in an organic solvent arising from the triplet radical pair generated by Norrish Type I reaction was formed, and its yield was dependent on the alkyl chain length. In an organic solvent, since the cage lifetime is shorter than the time required for intersystem crossing (ISC) of the triplet radical pair to the singlet radical pair the recombination with or without rearrangement of the primary radical pair (phenylacetyl and benzyl) does not occur. Recombination without rearrangement within the capsule as inferred from monitoring the racemization of the optically pure α-alkyl deoxybenzoins suggesting the capsule's stability for at least 10(-8) s (the time required for ISC) is consistent with our previous photophysical studies that showed partial opening and closing of the capsule in the time range of microseconds

Cavitand octa acid forms a nonpolar capsuleplex dependent on the molecular size and hydrophobicity of the guest

We have been exploring the use of a deep cavity cavitand known by the trivial name 'octa acid' as a photochemical reaction cavity for manipulating photochemical and photophysical properties of organic molecules. In the current study, we have monitored the micropolarity of the interior of the cavitand by recording the fluorescence of five different organic probes. They all indicate that the interior of octa acid capsuleplex (2:1, H/G complex) is nonpolar and does not contain water molecules in spite of the complex being present in water. The nature of the octa acid-probe complex in each case has been characterized by <SUP>1</SUP>H NMR data to be a 2:1 capsuleplex. Photophysical and <SUP>1</SUP>H NMR experiments were employed to probe the factors that control the structure of the complex, 2:2, 2:1, and 1:1. The data we have on hand suggest that the structure of the host/guest complex depends on the size and hydrophobicity of the guest molecule

Dendrimers as photochemical reaction media. Photochemical behavior of unimolecular and bimolecular reactions in water-soluble dendrimers

Synthesis and studies of poly(alkyl aryl ether) dendrimers, possessing carboxylic acid functionalities at their peripheries, are reported. 5-Bromopentyloxy methylisophthalate was utilized as the monomer to O-alkylate the phenolic hydroxyl groups of poly(alkyl aryl ether) dendrimers. Dendrimers of first, second, and third generations, possessing 6, 12, and 24 carboxylic acids, respectively, were thus prepared. These dendrimers were soluble in alkaline aqueous solutions, and the ensuing microenvironmental properties of the aqueous solutions were assessed by pyrene solubilization studies. Upon establishing the presence of nonpolar microenvironments within the dendritic structures, solubilizations of few organic substrates were conducted and their photochemical behaviors were assessed. Specifically, the photolysis of 1-phenyl-3-p-tolyl-propan-2-one and benzoin ethyl ether and photodimerization of acenaphthylene were conducted. These studies revealed that the product distribution and the "cage effect" were more distinct and efficient for the third generation dendrimer, than for the first and second generation dendrimers. The photochemical studies of carboxylic acid functionalized dendrimers were compared to that of hydroxyl group terminated poly(alkyl aryl ether) dendrimers

Closed nanocontainer enables thioketones to phosphoresce at room temperature in aqueous solution

Thiocarbonyl compounds possess unusual photophysical properties: they fluoresce from S(2), phosphoresce from T(1) only at extremely low concentrations in solution at room temperature, have unit quantum yield of intersystem crossing from S(1) to T(1), undergo self-quenching at diffusion-controlled rates, and are quenched by ground-state oxygen leading to self-destruction. In this article, we are concerned with finding a new method to observe phosphorescence from thioketones at room temperature in aqueous solution at high concentrations. To achieve this goal, one needs to find ways to eliminate diffusion-limited self-quenching and oxygen quenching. We present here a general strategy that has allowed us to record phopshorescence from a number of thioketones in aqueous solution at room temperature. The method involves encapsulation of thioketone molecules within a "closed nanocontainer" made up of two cavitand molecules known by its trivial name as octa acid. In these supramolecular complexes, despite two thiocarbonyl compounds being present in close proximity, no self-quenching occurs within the confined space due to curtailment of their rotational freedom. Although phosphorescence could also be observed when these thioketones are included in open containers, such as cucurbiturils and cyclodextrines, the closed container made up of octa acid is found to be the best medium to observe phosphorescence from thioketones whose excited state chemistry is essentially controlled by self-quenching