Lipolysis of didecanoyl-lecithin/triolein mixed monolayers by phospholipaseA 2

A study of enzyme lipolysis by pancreatic phospholipaseA ₂ and by vipera berus phospholipaseA ₂ on monomolecular mixed films of didecanoyl-lecithin and triolein on an aqueous subphase of pH 8 has been carried out. The influence of the composition of the mixed film, the surface pressure of the film and the amount and type of the injected enzyme on the lipolysis rate were studied.In order to relate the lipolytic activity with the monolayer state, the compression isotherms of the didecanoyl-lecithin/triolein mixed monolayers have also been obtained.The resuls are compared to observations on lipolytic activity of phospholipaseA ₂ on the didecanoyl-lecithin/cholesterol mixed monolayers. Triolein improves the kinetic conditions of the lipolysis of lecithin films in a higher degree than cholesterol. Probably it increases the enzyme penetration by the fluidifying effect exerted on the lecithin monolayers.     

The foreign language cocktail party problem: Energetic and informational masking effects in non-native speech perception

Studies comparing native and non-native listener performance on speech perception tasks can distinguish the roles of general auditory and language-independent processes from those involving prior knowledge of a given language. Previous experiments have demonstrated a performance disparity between native and non-native listeners on tasks involving sentence processing in noise. However, the effects of energetic and informational masking have not been explicitly distinguished. Here, English and Spanish listener groups identified keywords in English sentences in quiet and masked by either stationary noise or a competing utterance, conditions known to produce predominantly energetic and informational masking, respectively. In the stationary noise conditions, non-native talkers suffered more from increasing levels of noise for two of the three keywords scored. In the competing talker condition, the performance differential also increased with masker level. A computer model of energetic masking in the competing talker condition ruled out the possibility that the native advantage could be explained wholly by energetic masking. Both groups drew equal benefit from differences in mean F0 between target and masker, suggesting that processes which make use of this cue do not engage language-specific knowledge.     

Some Maximal Function Fields and Additive Polynomials

We derive explicit equations for the maximal function fields F over 𝔽 _{q ²ⁿ} given by F = 𝔽 _{q ²ⁿ} (X, Y) with the relation A(Y) = f(X), where A(Y) and f(X) are polynomials with coefficients in the finite field 𝔽 _{q ²ⁿ} , and where A(Y) is q-additive and deg(f) = q ⁿ  + 1. We prove in particular that such maximal function fields F are Galois subfields of the Hermitian function field H over 𝔽 _{q ²ⁿ} (i.e., the extension H/F is Galois).     

A new ultra‐high‐vacuum variable temperature and high‐magnetic‐field X‐ray magnetic circular dichroism facility at LNLS

X‐ray magnetic circular dichroism (XMCD) is one of the most powerful tools for investigating the magnetic properties of different types of materials that display ferromagnetic behavior. Compared with other magnetic‐sensitive techniques, XMCD has the advantage of being element specific and is capable of separating the spin and magnetic moment contributions associated with each element in the sample. In samples involving, for example, buried atoms, clusters on surfaces or at interfaces, ultrathin films, nanoparticles and nanostructures, three experimental conditions must be present to perform state‐of‐the‐art XMCD measurements: high magnetic fields, low temperatures and an ultra‐high‐vacuum environment. This paper describes a new apparatus that can be easily installed at different X‐ray and UV beamlines at the Brazilian Synchrotron Light Laboratory (LNLS). The apparatus combines the three characteristics described above and different methods to measure the absorption signal. It also permits in situ sample preparation and transfer to another chamber for measurement by conventional surface science techniques such as low‐energy electron diffraction (LEED), reflection high‐energy electron diffraction (RHEED), X‐ray photoelectron spectroscopy (XPS) and X‐ray photoelectron diffraction (XPD). Examples are given of XMCD measurements performed with this set‐up on different materials.     

Two‐Dimensionally Ordered Plasmonic and Magnetic Nanostructures on Transferable Electron‐Transparent Substrates

Discovery of new plasmonic behaviors from nanostructured materials can be greatly accelerated by the ability to prepare and characterize their near‐field behaviors with high resolution in a rapid manner. Here, an efficient and cost‐effective way is reported to make 2D periodic nanostructures on electron‐transparent substrates for rapid characterization by transmission electron microscopy. By combining nanosphere lithography with a substrate float‐off technique, large areas of electron‐transparent periodic nanostructures can be achieved. For this study, the synthesis of plasmonic nanostructures of Ag, magnetic nanostructures of Co, and bimetallic nanostructures of Ag–Co are investigated. Characterization of the materials by a combination of transmission electron microscopy, far‐field optical spectroscopy, and magnetization measurements reveals that this new approach can yield useful nanostructures on transparent, flexible, and transferable substrates with desirable plasmonic and/or magnetic properties.     

Letter: Spin Polarised Magnetized Cylinders in Torsioned Spacetime

A Spin-polarised cylindrically symmetric exact class of solutions endowed with magnetic fields in Einstein-Cartan-Maxwell gravity is obtained. Application of matching conditions to this interior solution having an exterior as Einstein's vacuum solution shows that for this class of metrics the Riemann-Cartan (RC) rotation vanishes which makes the solution static. Therefore we end up with a magnetized static spin polarised cylinder where the pressure along the symmetry axis is negative.     

Near-barrier fusion, breakup and scattering for the Be + Sm system

Fusion, breakup and scattering for the ⁹Be + ¹⁴⁴Sm system at near barrier energies are investigated by different approaches. We show that at energies above the barrier there is a small complete fusion suppression when compared with predictions from a double folding potential and with a similar tightly bound system. At sub-barrier energies there is no significant deviation from the predictions using coupled channel calculations that do not include the breakup channel. The energy dependence of the optical potential does not show the usual threshold anomaly found in tightly bound systems. From a simultaneous analysis of fusion and scattering data we estimate the distance where breakup starts to occur.     

Characterization of dextrin hydrogels by FTIR spectroscopy and solid state NMR spectroscopy

Fourier transform infrared (FTIR) and ¹³C solid state nuclear magnetic resonance (NMR) spectroscopy were used to study dextrin structural changes occurring upon hydrogel formation by vinyl acrylate (VA) grafting and subsequent free radical polymerization. The degrees of VA substitution (DS) and polymerization (DP) were quantified up to 40%VA by FTIR intensity measurements and partial least squares (PLS)/FTIR, the latter being a faster and less error-prone method. Above 40%VA, both parameters are underestimated by FTIR. A spin counting NMR experiment showed high carbon observabilities for hydrogels and improved PLS/NMR models were achieved for DS and DP determination. Alternative NMR integration methods are hindered by the broad VA peaks and need for area correction, due to their CP dynamics. NMR changes in C1 profile showed that a single helical conformation predominates at lower %VA, being replaced by disordered conformations as %VA increases. Furthermore, a correlation FTIR/NMR study indicated that ring conformations are significantly affected in hydrogels, compared to unpolymerized dextrin.     

The Virtual Geoscience Workbench,VGW:Open Source tools for discontinuous systems

In 1989 work began on merging finite and discrete elements. During 1990 algorithmic solutions for the new combined method were developed, together with a C-based implementation known as the Y code. In 2004 these developments and implementations were published as a textbook. Queen Mary University of London (QMUL) and Imperial College are currently engaged in a research project to make Y codes in both 2D and 3D available in Open Source format and with mainly geoscience problems in mind. The result is a set of...