Constrained Extremum Problems,Regularity Conditions and Image Space Analysis. Part II: The Vector Finite-Dimensional Case

The scalar finite-dimensional case has been discussed in the first part of this work series, which aims at exploiting the image space analysis to establish a general regularity condition for constrained extremum problems. Based on this preliminary result, the present paper dedicates itself to further study the regularity conditions for vector constrained extremum problems in a Euclidean space. The case of infinite-dimensional image will be the subject of a subsequent paper.     

Structure, electronic, and optical properties of TiO2 atomic clusters: an ab initio study

Atomic clusters of TiO(2) are modeled by means of state-of-the-art techniques to characterize their structural, electronic and optical properties. We combine ab initio molecular dynamics, static density functional theory, time-dependent density functional theory, and many body techniques, to provide a deep and comprehensive characterization of these systems. TiO(2) clusters can be considered as the starting seeds for the synthesis of larger nanostructures, which are of technological interest in photocatalysis and photovoltaics. In this work, we prove that clusters with anatase symmetry are energetically stable and can be considered as the starting seeds to growth much larger and complex nanostructures. The electronic gap of these inorganic molecules is investigated, and shown to be larger than the optical gap by almost 4 eV. Therefore, strong excitonic effects appear in these systems, much more than in the corresponding bulk phase. Moreover, the use of various levels of theory demonstrates that charge transfer effects play an important role under photon absorption, and therefore the use of adiabatic functionals in time dependent density functional theory has to be carefully evaluated.     

Identification of thuridillin-related aldehydes from Mediterranean sacoglossan mollusk Thuridilla hopei

The re-investigation of the Mediterranean opisthobranch Thuridilla hopei resulted in the isolation and chemical characterization of three novel nor-diterpene aldehydes, nor-thuridillonals 2–4, structurally related to co-occurring already reported thuridillins. Analogous with the thuridillins, the new molecules were thought to derive from the same dietary precursor epoxylactone 1.     

Design of a compact photonic crystal sensor

The development of technology in photonic crystal (PC) structures has seen rapid progress. Using PCs in biosensing area may open new venues to achieve single molecule detection, and high resolution scanning. A novel PC sensor with improved performances, in terms of size, compactness and sensitivity is presented in this paper. The sensing element consists of dielectric cylinders with varying radius introduced along <01> and <10> directions of the crystal. The results show that the peak wavelength shifts to the high frequency region when only six cylinders are filled with analytes. Also, the peaks show a larger shift compared to the structure obtained using the entire PC waveguide as sensing region. The proposed sensor shows a better sensitivity to water than other analytes, where the peak wavelength tends to shift towards the low frequency region.     

Synthesis and Biological Evaluation of Halogenated E-Stilbenols as Promising Antiaging Agents

The increased risk of illness and disability is related to the age inevitable biological changes. Oxidative stress is a proposed mechanism for many age-related diseases. The crucial importance of polyphenol pharmacophore for aging process is largely described thanks to its effects on concentrations of reactive oxygen species. Resveratrol (3,5,4′-trihydroxy-trans-stilbene, RSV) plays a critical role in slowing the aging process but has a poor bioavailabity after oral intake. In this present work, a series of RSV derivatives was designed, synthesized, and evaluated as potential antioxidant agents. These derivatives contain substituents with different electronic and steric properties in different positions of aromatic rings. This kind of substituents affects the activity and the bioavailability of these compounds compared with RSV used as reference compound. Studies of Log P values demonstrated that the introduction of halogens gives the optimum lipophilicity to be considered promising active agents. Among them, compound 6 showed the higher antioxidant activity than RSV. The presence of trifluoromethyl group together with a chlorine atom increased the antioxidant activity compared to RSV.     

Reversed‐phase high‐performance liquid chromatography method with fluorescence detection to screen nitric oxide synthases inhibitors

Nitric oxide synthase (NOS) inhibitors are potential drug candidates due to the critical role of an excessive production of nitric oxide in a range of diseases. At present, the radiometric detection of l ‐[³H]‐citrulline produced from l ‐[³H]‐arginine during the enzymatic reaction is one of the most accepted methods to assess the in vitro activity of NOS inhibitors. Here we report a fast, easy, and cheap reversed‐phase high‐performance liquid chromatography method with fluorescence detection, based on the precolumn derivatization of l ‐citrulline with o‐phthaldialdehyde/N‐acetyl cysteine, for the in vitro screening of NOS inhibitors. To evaluate enzyme inhibition by the developed method, N‐[3‐(aminomethyl)benzyl]acetamidine, a potent and selective inhibitor of inducible NOS, was used as a test compound. The half maximal inhibitory concentration obtained was comparable to that derived by the well‐established radiometric assay.     

Cytosporin-related compounds from the marine-derived fungus Eutypella scoparia

Chemical investigation of the culture broth of the fungus Eutypella scoparia ICB-OBX, isolated from the marine pulmonate mollusc Onchidium sp., led to the finding of novel compounds 1 and 2, structurally related to angiotensin II binding inhibitors cytosporins, along with unrelated known nitrogen metabolites (compounds 3-5). The structure and the relative stereochemistry of the novel metabolites were assigned mainly by a detailed analysis of two-dimensional NMR techniques whereas the absolute stereochemistry was proposed by modified Mosher's method. Compound 2 contains an unusual cyclic carbonate functionality that is rare among natural products.     

Furofuranic glycosylated lignans: a gas-phase ion chemistry investigation by tandem mass spectrometry

Alkali metal cation adducts, [M+Alk](+), and [M-H](-) ions of four known glycosylated furofuran lignans, (+)-pinoresinol 4-O-beta-D-glucopyranoside, (+)-phylliroside, (+)-8-hydroxypinoresinol 4-O-beta-D-glucopyranoside, and (+)-8-hydroxypinoresinol 8-O-beta-D-glucopyranoside, recently isolated from Carex distachya, were generated by electrospray ionization and allowed to undergo collisionally activated dissociation (CAD) in a quadrupole ion trap (QIT) and in a triple quadrupole (TQ) mass spectrometer. CAD mass spectra of [M+Na](+) and [M+Li](+) adducts revealed the presence of structurally diagnostic product ions. CAD mass spectra of deprotonated glycosylated furofuran lignans showed the typical neutral loss of 162 Da when the glucose residue was bound to a phenolic oxygen atom. When glycosylation occurred at an alcoholic oxygen, as for (+)-8-hydroxypinoresinol 8-O-beta-D-glucopyranoside, a neutral loss of 180 Da represented the main fragmentation pathway. Selective hydrogen/deuterium (H/D) exchange of all the acidic hydrogen atoms of furofuran glycosides, performed by introducing lignan glycosides in D(2)O/CH(3)OD solutions, were employed to obtain information on the nature of the product ions generated during TQ/CAD processes. Energy-resolved TQ/CAD mass spectra of deprotonated lignan glycosides and their deprotonated aglycones were used in a qualitative way to infer information on the integrated energetic picture of CAD fragmentations and to investigate the mechanism of the predominant dissociation/isomerization processes. On the basis of the hypothesized fragmentation mechanisms, gas-phase features of the furofuran ring were derived. The presence of an OH substituent in the C8 position decreased the electron density in the adjacent C8' position, modifying the fragmentation pathway.     

Calorimetric analysis of three hydroxy acids as markers for quality and safety in food

A new analytical methodology to quantify three hydroxy acids (orotic, ascorbic, L-malic acids), by isothermal solution microcalorimetry, was outlined and applied to different foods. Three specific enzymatic reactions were used to ensure the correctness of the results. The considered acids can be considered as markers in food quality for their biochemical peculiarities. The enzymatic microcalorimetric method is very reliable and linearity is satisfied in the concentration ranges useful for food analyses. The analytical results of the underlined method are very accurate, precise, sensitive and in good agreement with the values obtained with other common methods.