Spatial information transmission using orthogonal mutual coherence coding

We use the coherence of a light beam to encode spatial information. We apply this principle to obtain spatial superresolution in a limited aperture system. The method is based on shaping the mutual intensity function of the illumination beam in a set of orthogonal distributions, each one carrying the information for a different frequency bandpass or spatial region of the input object. The coherence coding is analogous to time multiplexing but with multiplexing time slots that are given by the coherence time of the illumination beam. Most images are static during times much longer than this coherence time, and thus the increase of resolution in our system is obtained without any noticeable cost.     

Characterization of a 20 kHz sonoreactor. Part I: analysis of mechanical effects by classical and numerical methods

Numerical simulations have been carried out in order to characterize the ultrasonic field propagation and to obtain the spatial distribution of the mechanical effect derived from it. The results have been compared with those obtained with different classical physical methods (calorimetry, aluminium foil erosion, thermal probes) and have given useful information about the influence of the presence of probes and auxiliary tools in the ultrasonic field. All these information have been used for the development of the Part II of this work: analysis of chemical effects, providing an accurate picture of the reaction environment in the sonoreactor used (20 kHz, 100 W supplied by Undatim) for further uses in sonoelectrochemical studies.     

(S,S)-(+)-pseudoephedrine as chiral auxiliary in asymmetric acetate aldol reactions

The asymmetric acetate-type aldol reaction using (S,S)-(+)-pseudoephedrine has been studied in detail. Experimental variables like the nature of the metal counterion of the enolate, the presence of additives and the structure of the aldehyde have been examined in order to reach to the highest possible yields and diastereoselectivities.     

Relaxations in poly(vinyl alcohol) and in poly(vinyl acetate) detected by fluorescence emission of 4-aminophthalimide and prodan

Steady-state and time-resolved emission spectroscopy (TRES) of the medium-sensitive probes 4-aminophthalimide (4-AP) and 6-propionyl-2-(dimethylamino)naphthalene (Prodan) were performed at 77 and 298 K in vacuum-sealed thin films of poly(vinyl alcohol) (PVA) and poly(vinyl acetate) (PVAc). The two probes show similar red-edge effect in steady state emission and a red shift with time in TRES in PVA. In PVAc the red shifts are much smaller and the spectral shift for 4-AP is slower. 4-AP locates in highly polar environments in PVA, where H-bond interaction with the polymer is important. Prodan locates in less polar environments, as evidenced by the position of the emission maximum with respect to reference solvents. Consequently, the observed monoexponential spectral red shift with time of 4-AP in PVA and in PVAc is attributed to relaxation of the interaction of the probe with the hydroxy and acetate moieties, respectively. The more intense interaction of the lighter -OH moiety with the probes explains the greater and faster spectral shift observed in PVA compared to PVAc. The lifetime of this monoexponential spectral shift is independent of temperature in PVA and takes place with a highly negative activation entropy. This fact is attributed to a collective rearrangement of -OH groups to better interact with the excited state. This relaxation nevertheless does not account for the complete accommodation of the excited state. Prodan shows a linear variation of the spectral shift with time that can be explained by microheterogeneity. In PVA, the width at half-maximum of the emission spectra does not change with time for Prodan and it decays with a lifetime similar to the lifetime of the spectral shift in the case of 4-AP. The differences in the behavior of the probes are attributed to their different average location in the polymer matrix.     

Rigid spacer-mediated synthesis of bis-spiroketal ring systems: stereoselective synthesis of nonsymmetrical spiro disaccharides

The application of the "rigid spacer-mediated linkage between nonreacting centers" concept to the preparation of nonsymmetrical bis-spiroketal structures is demonstrated by the stereoselective synthesis of the bis-spiro fructodisaccharide 1, a minor component of industrial caramels. An o-xylylene bridge has been used to limit the conformational space during the intramolecular glycosylation-spirocyclization reaction of a difructopyranose precursor, thus controlling both the ring size and the stereochemistry at the spiro centers. [Structure: see text]     

Electrophilic properties of nitroheterocyclic compounds. Potential hypoxic cells radiosensitizers

Investigation of the reduction potential and calculation of the partition coefficient n-octanol/water allow the assessment of the potential suitability of nitropirydine N-oxide compounds in radiotherapy of cancer. Experiments were carried out using cyclic voltammetry with HMDE as working electrode. The electrode reduction of the investigated compounds is quite irreversible and strongly dependent on pH.     

The stereocontrolled total synthesis of altohyrtin A/spongistatin 1: fragment couplings, completion of the synthesis, analogue generation and biological evaluation

The antimitotic marine macrolide altohyrtin A/spongistatin 1 has been synthesised in a highly convergent and stereocontrolled manner, thus contributing to the replenishment of the largely exhausted material from the initial isolation work. Coupling of the AB- and CD-spiroacetal subunits by a stereoselective aldol reaction was achieved by using either a lithium (67 : 33 dr) or boron enolate (90 : 10 dr). A highly (Z)-selective Wittig coupling was used to unite the northern hemisphere aldehyde with the southern hemisphere phosphonium salt . Deprotection and subsequent regioselective macrolactonisation on a triol seco-acid completed the synthesis of altohyrtin A. Two structural analogues were also prepared and evaluated as growth inhibitory agents against a range of human tumour cell lines, including Taxol-resistant strains, alongside altohyrtin A and paclitaxel (Taxol), revealing that dehydration in the E-ring is tolerated and results in enhanced cytotoxicity (at the low picomolar level), whereas the presence of the full C44-C51 side-chain appears to be crucial for biological activity.     

Identification of smoked Atlantic salmon (Salmo salar) and rainbow trout (Oncorhynchus mykiss) using PCR-restriction fragment length polymorphism of the p53 gene

Raw and smoked samples of Atlantic salmon (Salmo salar) and rainbow trout (Oncorhynchus mykiss) were identified using polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) of the p53 gene. DNA from S. salar and 0. mykiss was amplified by using primers flanking exons 5 to 6 of the p53 nuclear gene. PCR products of different length were obtained for each species (532 and 518 base pairs, respectively). Sequences of PCR products obtained from S. salar and O. mykiss were compared in the search for polymorphic restriction sites. The restriction fragments obtained with Eco RV, Hinf I, and Taq I endonucleases showed interspecific polymorphism, making it a useful method for identification of Atlantic salmon and rainbow trout.     

Construction of Heterometallic Cubanes

Incorporation of M(CO)(3) fragments by trinuclear Ti complexes [{Ti(3)Cp(μ(3)-CR)}(μ-O)(3)] and [{Ti(3)Cp(μ(3)-N)}(μ-NH)(3)] (Cp*=eta(5)-C(5)Me(5)) leads to the formation of an unprecedented class of heterometallic clusters with cubane structure [e.g., Eq. (a)]. Density functional calculations on these complexes indicate the existence of electron delocalization in the Ti(3)M cores (M=Cr, Mo, W).