Influence of human serum albumin on photodegradation of folic acid in solution

It has been proposed that photodegradation of folates may be the reason for the pigmentation of races living under high fluence rates of ultraviolet radiation. The photodegradation of folic acid (FA) induced by ultraviolet-A (UV-A) radiation, in solution and in the presence of human serum albumin (HSA), was studied with absorption and fluorescence spectroscopy. FA photodegradation, with formation of p-aminobenzoyl-l-glutamic acid, 6-formylpterin and pterin-6-carboxylic acid, was found to follow an exponential trend. A scheme of FA photodegradation, which involves photosensitization of FA degradation by its photoproducts, was proposed. The rate of FA photodegradation decreased drastically in the presence of HSA, whereas the spectral characteristics of the photoproducts remained constant. The reduction of the FA photodegradation rate by HSA was accompanied by degradation of tryptophan in HSA. Tryptophan, when added to solutions of FA, had a similar effect as HSA. In solutions of FA and HSA the FA photoproducts cause photodamage mainly to HSA rather than to FA itself. The oxygen dependence of FA photodegradation and the inhibition of this process by sodium azide indicate that singlet oxygen may participate in the photosensitizing activity of FA photoproducts.     

A comparison study between a disposable electrochemical DNA biosensor and a Vibrio fischeri-based luminescent sensor for the detection of toxicants in water samples

In the present study, a comparison between a disposable electrochemical DNA biosensor and a Vibrio fischeri-based luminescent sensor for the detection of toxicants in water samples was made.In order to realize this study, a disposable electrochemical DNA biosensor has been reported. The DNA biosensor is assembled by immobilizing double stranded Calf Thymus DNA onto the surface of a disposable carbon screen-printed electrode. The oxidation signal of the guanine base, obtained by a square wave voltammetric scan, is used as analytical signal to detect the DNA damage; the presence of low molecular weight compounds with affinity for nucleic acids is measured by their effect on the guanine oxidation peak.Wastewater samples provided during First European Interlaboratory Exercise on water toxicity in the course of the project SWIFT-WFD were analyzed, and biosensor results were compared with a currently used toxicity test ToxAlert^®100 based on the bioluminescence inhibition of Vibrio fischeri. This test have been used because is rapid, easy handling and cost effectively responses for the toxicity assessment in real water samples.The results showed a promising correlation between two tests used for the detection of toxic compounds in water samples.     

The effect of skin permeation enhancers on the formation of porphyrins in mouse skin during topical application of the methyl ester of 5-aminolevulinic acid

The influence of skin permeation enhancers, such as dimethyl sulphoxide (DMSO) and 1-[2-(decylthio)ethyl]azacyclopentan-2-one (HPE-101), Labrafac CC, Labrafil, Labrasol and Transcutol in a concentration of 10% (wt./wt.) on the formation of porphyrins in normal mouse skin from topical application of creams with methyl 5-aminolevulinate (MAL) was studied. The concentration of porphyrins in the mouse skin was determined by direct fluorescence measurements. The results show that studied permeation enhancers increase the formation of porphyrins, and therefore also the skin penetration 2% MAL whereas for 10% and 20% (wt./wt.) MAL concentrations only DMSO, HPE-101 and Labrafac CC increased the porphyrin formation. At all studied MAL concentrations DMSO gave the largest enhancing effect, similarly to that of HPE-101. This suggests that in 2-20% MAL creams HPE-101 may be substituted by Labrafac CC to reduce skin irritation induced by HPE-101 without impairing the porphyrin formation.     

Anellated N-heterocyclic carbenes: 1,3-dineopentylnaphtho[2,3-d]imidazol-2-ylidene: synthesis, KOH addition product, transition-metal complexes, and anellation effects

Two novel anellated N-heterocyclic carbenes (NHC), 1,3-dineopentylnaphtho[2,3-d]imidazol-2-ylidene, and 1,3-dineopentyl-2-ylido-imidazolo[4,5-b]pyridine were obtained by reduction of the respective thiones with potassium, the former also by deprotonation of the corresponding naphthimidazolium hexafluorophosphate by using excess KH in THF. The use of equimolar amounts of KH provided an unexpected formal addition product of this NHC with KOH. X-ray crystal structure analysis of the adduct provided evidence for a distorted tetrameric N-heterocyclic alkoxide, stabilized by two THF molecules. In C(6)D(6) the compound undergoes disproportionation. Transition-metal complexes [(NHC)AgCl], [(NHC)Rh(cod)Cl], and (E)-[(NHC)(2)PdCl(2)] of the novel naphthimidazol-2-ylidene were synthesized. X-ray crystal structures and (1)H and (13)C NMR spectroscopic data provided detailed structural information. Comparing characteristic data with those of nonanellated and differently anellated NHCs or their complexes provides information on the influence of the extended anellation.     

Topologically novel multiple rotaxanes and catenanes based on tetraurea calix[4]arenes

Calix[4]arenes bearing at their wide rim four urea residues easily form hydrogen bonded dimeric capsules. This has been used to preorganise alkenyl functions attached to these urea groups for their controlled connection via metathesis reaction. Multimacrocyclic tetraurea derivatives are thus obtained in excellent yields via heterodimers which are formed exclusively with tetratosylurea derivatives. Heterodimerisation of such bis- and tetraloop tetraureas leads analogously to multicatenanes, or to rotaxanes by stoppering. Huge macrocycles are detached from tetraloop derivatives by cleavage of the urea function.     

Aspects on the Functional Optimization of an Industrial Robot Structure Implemented in Military Logistical Activities

The authors of the present paper outline aspects on the optimization of the a TR-type industrial robot structure movements in order to generate the manipulation space to a flexible manufacturing cell with a parallel organization designed for the pallet and container operation of paint-filled recipients. The paper contains the direct and inverted geometrical modelling of the robot structure using the 3*3 rotation matrix method and the algebra method. After knowing the characteristic point movement of the prehension device, graphics for the variation of the TR robot's general coordinates and for the trajectory of the prehension device's characteristic point of its work space were performed by using the Mathematica 6.0 soft. (© 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)     

On the monodromy action on Milnor fibers of graphic arrangements

We analyze the monodromy action, over the rationals, on the first homology group of the Milnor fiber, for arbitrary subarrangements of Coxeter arrangements. We propose a combinatorial formula for the monodromy action, involving Aomoto complexes in positive characteristic. We verify the formula, in cases A, B and D.     

A new Fenchel dual problem in vector optimization

We introduce a new Fenchel dual for vector optimization problems inspired by the form of the Fenchel dual attached to the scalarized primal multiobjective problem. For the vector primal-dual pair we prove weak and strong duality. Furthermore, we recall two other Fenchel-type dual problems introduced in the past in the literature, in the vector case, and make a comparison among all three duals. Moreover, we show that their sets of maximal elements are equal.     

On neutrino masses via CPT violating Higgs interaction in the Standard Model

The Lorentz invariant CPT   violation by using non-local interactions is naturally incorporated in the Higgs coupling to neutrinos in the Standard Model, without spoiling the basic SU_(2)L×U(1)$\mathit{SU}{(2)}_L\times U(1)$ gauge symmetry. The neutrino–antineutrino mass splitting is thus realized by the mechanism which was proposed recently, assuming the neutrino masses to be predominantly Dirac-type in the Standard Model.     

The influence of UV exposure on 5-aminolevulinic acid-induced protoporphyrin IX production in skin.

The skin of nude mice was exposed to erythemogenic doses of UV radiation, which resulted in erythema with edema. An ointment containing 5-aminolevulinic acid (ALA) was topically applied on mouse and human skin. Differences in the kinetics of protoporphyrin accumulation were investigated in normal and UV-exposed skin. At 24 and 48 h after UV exposure, skin produced significantly less protoporphyrin IX (PpIX) than skin unexposed to UV. Human skin on body sites frequently exposed to solar radiation (the lower arm) also produced less PpIX than skin exposed more rarely to the sun (the upper arm). It is concluded that UV radiation introduces persisting changes in the skin, relevant to its capability of producing PpIX from ALA. The observed differences in ALA-induced PpIX fluorescence may be the result of altered penetration of ALA through the stratum corneum or altered metabolizing ability of normal and UV-exposed skin (or both).