IR/Raman spectroscopy and DFT calculations of cyclic di-amino acid peptides. Part III: comparison of solid state and solution structures of cyclo(L-Ser-L-Ser)

B3-LYP/cc-pVDZ calculations of the gas-phase structure and vibrational spectra of the isolated molecule cyclo(L-Ser-L-Ser), a cyclic di-amino acid peptide (CDAP), were carried out by assuming C-2 symmetry. It is predicted that the minimum-energy structure is a boat conformation for the diketopiperazine (DKP) ring with both L-Beryl side chains being folded slightly above the ring. An additional structure of higher energy (15.16 kJ mol(-1)) has been calculated for a DKP ring with a planar geometry, although in this case two fundamental vibrations have been calculated with imaginary wavenumbers. The reported X-ray crystallographic structure of cyclo(L-Ser-L-Ser), shows that the DKP ring displays a near-planar conformation, with both the two L-Beryl side chains being folded above the ring. It is hypothesized that the crystal packing forces constrain the DKP ring in a planar conformation and it is probable that the lower energy boat conformation may prevail in the aqueous environment. Raman scattering and Fourier-transform infrared (FT-IR) spectra of solid state and aqueous solution samples of cyclo(L-Ser-L-Ser) are reported and discussed. Vibrational band assignments have been made on the basis of comparisons with the calculated vibrational spectra and band wavenumber shifts upon deuteration of labile protons. The experimental Raman and IR results for solid-state samples show characteristic amide I vibrations which are split (Raman:1661 and 1687 cm(-1), IR:1666 and 1680 cm(-1)), possibly due to interactions between molecules in a crystallographic unit cell. The cis amide I band is differentiated by its deuterium shift of ~ 30 cm(-1), which is larger than that previously reported for trans amide I deuterium shifts. A cis amide II mode has been assigned to a Raman band located at 1520 cm(-1). The occurrence of this cis amide II mode at a wavenumber above 1500 cm(-1) concurs with results of previously examined CDAP molecules with low molecular weight substituents on the C-alpha atoms, and is also indicative of a relatively unstrained DKP ring.

Automated analysis of non-mass-enhancing lesions in breast MRI based on morphological, kinetic, and spatio-temporal moments and joint segmentation-motion compensation technique

Dynamic contrast-enhanced magnetic resonance imaging (DCE-MRI) represents an established method for the detection and diagnosis of breast lesions. While mass-like enhancing lesions can be easily categorized according to the Breast Imaging Reporting and Data System (BI-RADS) MRI lexicon, a majority of diagnostically challenging lesions, the so called non-mass-like enhancing lesions, remain both qualitatively as well as quantitatively difficult to analyze. Thus, the evaluation of kinetic and/or morphological characteristics of non-masses represents a challenging task for an automated analysis and is of crucial importance for advancing current computer-aided diagnosis (CAD) systems. Compared to the well-characterized mass-enhancing lesions, non-masses have no well-defined and blurred tumor borders and a kinetic behavior that is not easily generalizable and thus discriminative for malignant and benign non-masses. To overcome these difficulties and pave the way for novel CAD systems for non-masses, we will evaluate several kinetic and morphological descriptors separately and a novel technique, the Zernike velocity moments, to capture the joint spatio-temporal behavior of these lesions, and additionally consider the impact of non-rigid motion compensation on a correct diagnosis.

Microplastics Alter the Properties and Sinking Rates of Zooplankton Faecal Pellets

Plastic debris is a widespread contaminant, prevalent in aquatic ecosystems across the globe. Zooplankton readily ingest microscopic plastic (microplastic, < 1 mm), which are later egested within their faecal pellets. These pellets are a source of food for marine organisms, and contribute to the oceanic vertical flux of particulate organic matter as part of the biological pump. The effects of microplastics on faecal pellet properties are currently unknown. Here we test the hypotheses that (1) faecal pellets are a vector for transport of microplastics, (2) polystyrene microplastics can alter the properties and sinking rates of zooplankton egests and, (3) faecal pellets can facilitate the transfer of plastics to coprophagous biota. Following exposure to 20.6 μm polystyrene microplastics (1000 microplastics mL–1) and natural prey (∼1650 algae mL–1) the copepod Calanus helgolandicus egested faecal pellets with significantly (P < 0.001) reduced densities, a 2.25-fold reduction in sinking rates, and a higher propensity for fragmentation. We further show that microplastics, encapsulated within egests of the copepod Centropages typicus, could be transferred to C. helgolandicus via coprophagy. Our results support the proposal that sinking faecal matter represents a mechanism by which floating plastics can be vertically transported away from surface waters.

Chemical abundances and winds of massive stars in M31: a B-type supergiant and a WC star in OB 10

We present high quality spectroscopic data for two massive stars in the OB 10 association of M31, OB 10-64 (B0 la) and OB 10-WRI (WC6). Medium resolution spectra of both stars were obtained using the ISIS spectrograph on the William Herschel Telescope. This is supplemented with Hubble Space Telescope STIS UV spectroscopy and Keck I HIRES data for OB 10-64. A non- local thermodynamic equilibrium (LTE) model atmosphere and abundance analysis for OB 10-64 is presented, indicating that this star has similar photospheric CNO, Mg and Si abundances to solar neighbourhood massive stars. A wind analysis of this early B-type supergiant reveals a mass-loss rate of (M)over dot = 1.6 x 10(-6) M-circle dot yr(-1), and v(infinity) = 1650 km s(-1). The corresponding wind momentum is in good agreement with the wind momentum-luminosity relationship found for Galactic early-B supergiants. Observations of OB 10-WRI are analysed using a non-LTE, line-blanketed code, to reveal approximate stellar parameters of log L/L-circle dot similar to 5.7, T-* - 75 kK, v(infinity) similar to 3000 km s(-1), (M)over dot/(M-circle dot yr(-1)) similar to 10(-4.3) adopting a clumped wind with a filling factor of 10 per cent. Quantitative comparisons are made with the Galactic WC6 star HD 92809 (WR23) revealing that OB 10-WR1 is 0.4 dex more luminous, though it has a much lower C/He ratio (similar to0.1 versus 0.3 for HD 92809). Our study represents the first detailed, chemical model atmosphere analysis for either a B-type supergiant or a Wolf- Rayet (WR) star in Andromeda, and shows the potential of how such studies can provide new information on the chemical evolution of galaxies and the evolution of massive stars in the local Universe.

Behavior of the heterogeneous electron-transfer rate constants of arenes and substituted anthracenes in room-temperature ionic liquids

We report the anodic oxidation of several arenes and anthracenes within room-temperature ionic liquids (RTILs). In particular, the heterogeneous electron-transfer rates (k(0)) for substituted anthracenes and arenes are also investigated in 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([C(2)mim][NTf2]) and found not to obey the outer-sphere Marcus-type behavior of these compounds in contrast to the behavior in traditional organic solvents,in particular the predictions for k(0) with molecular size and solvent static dielectric constant. To obtain the electron-transfer rate for 9-phenylanthracene, the dimerization and heterogeneous electron-transfer kinetics of its electrogenerated radical cations is studied in [C(2)mim][NTf2] and eight other RTILs and are both found to be largely independent of the solution viscosity.

The Architecture of Seduction: An Analysis on Digital Architectures within Consumer Society

Currently new digital tools used in architecture are often at the service of a conception of architecture as a consumer society’s cultural good. Within this neoliberal cultural frame, architects’ social function is no longer seen as the production of urban facts with sense of duty, but as a part within the symbolic logic that rules the social production of cultural values as it was defined by Veblen and developed by Baudrillard. As a result, the potential given by the new digital tools used in representation has shifted from an instrument used to verify a built project to two different main models: At the one hand the development of pure virtual architectures that are exclusively configured within their symbolic value as artistic “images” easily reproducible. On the other hand the development of all those projects which -even maintaining their attention to architecture as a built fact- base their symbolic value on the author’s image and on virtual aesthetics and logics that prevail over architecture’s materiality. Architects’ sense of duty has definitely reached a turning point.