Novel procedure for the identification of proteins by mass fingerprinting combining two-dimensional electrophoresis with fluorescent SYPRO red staining

The fluorescent sensitive SYPRO Red dye was successfully employed to stain proteins in two-dimensional gels for protein identification by peptide mass fingerprinting. Proteins which are not chemically modified during the SYPRO Red staining process are well digested enzymatically in the gel and hence the resulting peptides can be efficiently eluted and analysed by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). A SYPRO Red two-dimensional gel of a complex protein extract from Candida albicans was analysed by MALDI-TOF MS. The validity of SYPRO Red staining was demonstrated by identifying, via peptide mass fingerprinting, 10 different C. albicans proteins from a total of 31 selected protein spots. The peptide mass signal intensity, the number of matched peptides and the percentage of coverage of protein sequences from SYPRO Red-stained proteins were similar to or greater than those obtained in parallel with the modified silver protein gel staining. This work demonstrates that fluorescent SYPRO Red staining is compatible with the identification of proteins separated on polyacrylamide gel and that it can be used as an alternative to silver staining. As far as we know, this is the first report in which C. albicans proteins separated using 2-D gels have been identified by peptide mass fingerprinting. The improved technique described here should be very useful for carrying out proteomic studies.     

A Novel Domino Reaction: Cyclization of Alkynyl Sulfides by Reaction with IPy2BF4

Formation of polycyclic structures within a few minutes: The intramolecular cyclization of diynes, activated by a benzenesulfenyl substituent, upon reaction with IPy₂BF₄ proceeds as an efficient exo–endo coupling. A subsequent novel Friedel–Crafts-like ring closure provides the product [Eq. (1)]. Thus, intra- and intermolecular cyclizations can be carried out.     

Theoretical Study on Hydrogen‐Bond Effects in IR Spectra of High‐ and Low‐Temperature Phases of Nitric Acid Dihydrate

The low‐ and high‐temperature phases (α and β, respectively) of solid nitric acid dihydrate (NAD) are studied in depth by DFT methods. Each phase contains two types of complex structures (H₃O⁺) ? (H₂O), designated A and B, with different hydrogen‐bonding (HB) characteristics. The theoretical study reveals that type A complexes are weakly bound and could be described as (H₃O)⁺ and H₂O aggregates, with decoupled vibrational modes, whereas in type B structures the proton is situated close to the centre of the O ??? O bond and induces strong vibrational coupling. The proton‐transfer mode is predicted at quite different wavenumbers in each complex, which provides an important differentiating spectral feature, together with splitting of some bands in β‐NAD. Theoretical spectra are estimated by using two GGA parameterizations, namely, PBE and BLYP. The potential‐energy surface for each type of HB in NAD is also studied, as is the spectral influence of displacement of the shared H atom along the O? O bond. The results are compared to literature infrared spectra recorded by different techniques, namely, transmission and reflection–absorption, with both normal and tilted incident radiation. This work provides a thorough assignment of the observed spectra, and predictions for some spectra not yet available. The usefulness of high‐level theoretical calculations as performed herein to discriminate between two phases of a solid crystal is thus evidenced.     

Uncertainty studies of topographical measurements on steel surface corrosion by 3D scanning electron microscopy

Pitting corrosion is a damage mechanism quite serious and dangerous in both carbon steel boiler tubes for power plants which are vital to most industries and stainless steels for orthopedic human implants whose demand, due to the increase of life expectation and rate of traffic accidents, has sharply increased. Reliable methods to characterize this kind of damage are becoming increasingly necessary, when trying to evaluate the advance of damage and to establish the best procedures for component inspection in order to determine remaining lives and failure mitigation. A study about the uncertainties on the topographies of corrosion pits from 3D SEM images, obtained at low magnifications (where errors are greater) and different stage tilt angles were carried out using an in-house software previously developed. Additionally, measurements of pit depths on biomaterial surfaces, subjected to two different surface treatments on stainless steels, were carried out. The different depth distributions observed were in agreement with electrochemical measurements.     

Boundary Values of Harmonic Bloch Functions in Lipschitz Domains: A Martingale Approach

In this paper, the boundary behaviour of a certain class of harmonic functions in Lipschitz domains is studied. It continues the work of N. Makarov on the boudary behaviour of analytic Bloch functions in the unit disk. Certain means associated with the function allow to approximate it by a martingale, and the boudary properties of the function are transferred to the asymptotic behaviour of the martingale.     

Method of achieving phase delay with wide optical bandwidth in multimode interference devices

A completely passive method of achieving phase delays inside multimode interference devices is presented. The desired relative phase is obtained by adjustment of the width of the waveguides in conjunction with the tapers to avoid interference inside the multimode section. One can generally apply the delay lines to avoid the use of active elements, and they are less sensitive to changes in wavelength than the traditional method with bends. Using this method, we have designed and analyzed a zero-to-one mode converter. The converter exhibits minimum excess loss of 0.100 and 0.102 for TE and TM polarization, respectively. A very large 1-dB bandwidth exceeding 350 nm is achieved.     

Electrodeposition for obtaining homogeneous or heterogeneous cobalt-copper films

Direct electrodeposition of heterogeneous deposits may be an alternative method for preparing cobalt-copper coatings with magnetoresistive properties. Co-Cu electrodeposition was obtained in sulfate baths containing different citrate concentrations in order to prepare either homogeneous or heterogeneous Co-Cu deposits. X-ray diffraction (XRD) and voltammetric stripping analysis were used to study the kind of deposits formed. Citrate-free baths produced heterogeneous films, although dendritic growth was observed, thus increasing the deposit's thickness. Increasing the Cu(II)/Co(II) ratio in solution enabled the formation of smoother deposits. The presence of citrate at up to twice the total metallic concentration in the bath improved the morphological aspects of the deposits, their structural heterogeneity being maintained. Higher citrate concentrations induced the loss of heterogeneity, and both electrochemical and diffraction peaks tended towards single peaks. Homogeneous Co-Cu deposits, formed by a solid solution structure, were obtained in highly complexed citrate baths.