Diffractively produced charm final states in 800-GeV/c pp collisions

We report the first observation of diffractively produced open charm in 800-GeV/c pp collisions of the type pp-->pD*X. We measure cross sections of sigma(diff)(D*+) = (0.185+/-0.044+/-0.054) (mu)b and sigma(diff)(D(*-)) = (0.174+/-0.034+/-0.029) (mu)b. Our measurements are based on 4.3x10(9) events recorded by FNAL E690 in the fixed-target run of 1991. We compare our results with previous fixed-target charm experiments.     

Linear polarization degree for detecting magnetic properties of small particles

Motivated by the recent advances with magnetic nanoparticles, in this research we propose a new technique for their characterization based on the measurement of certain polarimetric parameters of the scattered light, such as the linear polarization degree when it is determined at a "right-angle" scattering configuration. We will show the sensitivity of its spectral evolution with the magnetic properties of the particle.     

Structural Insights into the Design of Synthetic Nanobody Libraries

Single domain antibodies from camelids, or nanobodies, are a unique class of antibody fragments with several advantageous characteristics: small monomeric size, high stability and solubility and easy tailoring for multiple applications. Nanobodies are gaining increasing acceptance as diagnostic tools and promising therapeutic agents in cancer and other diseases. While most nanobodies are obtained from immunized animals of the camelid family, a few synthetic nanobody libraries constructed in recent years have shown the capability of generating high quality nanobodies in terms of affinity and stability. Since this synthetic approach has important advantages over the use of animals, the recent advances are indeed encouraging. Here we review over a dozen synthetic nanobody libraries reported so far and discuss the different approaches followed in their construction and validation, with an emphasis on framework and hypervariable loop design as critical issues defining their potential as high-class nanobody sources.     

Production and Digestibility Studies of β-Galactosyl Xylitol Derivatives Using Heterogeneous Catalysts of LacA β-Galactosidase from Lactobacillus Plantarum WCFS1

The synthesis of β-galactosyl xylitol derivatives using immobilized LacA β-galactosidase from Lactobacillus plantarum WCFS1 is presented. These compounds have the potential to replace traditional sugars by their properties as sweetener and taking the advantages of a low digestibility. The enzyme was immobilized on different supports, obtaining immobilized preparations with different activity and stability. The immobilization on agarose-IDA-Zn-CHO in the presence of galactose allowed for the conserving of 78% of the offered activity. This preparation was 3.8 times more stable than soluble. Since the enzyme has polyhistidine tags, this support allowed the immobilization, purification and stabilization in one step. The immobilized preparation was used in synthesis obtaining two main products and a total of around 68 g/L of β-galactosyl xylitol derivatives and improving the synthesis/hydrolysis ratio by around 30% compared to that of the soluble enzyme. The catalyst was recycled 10 times, preserving an activity higher than 50%. The in vitro intestinal digestibility of the main β-galactosyl xylitol derivatives was lower than that of lactose, being around 6 and 15% for the galacto-xylitol derivatives compared to 55% of lactose after 120 min of digestion. The optimal amount immobilized constitutes a very useful tool to synthetize β-galactosyl xylitol derivatives since it can be used as a catalyst with high yield and being recycled for at least 10 more cycles.     

Network DEA approach to airports performance assessment considering undesirable outputs

In this paper, a directional distance approach is proposed to deal with network DEA problems in which the processes may generate not only desirable final outputs but also undesirable outputs. The proposed approach is applied to the problem of modelling and benchmarking airport operations. The corresponding network DEA model considers two process (Aircraft Movement and Aircraft Loading) with two final outputs (Annual Passenger Movement and Annual Cargo handled), one intermediate product (Aircraft Traffic Movements) and two undesirable outputs (Number of Delayed Flights and Accumulated Flight Delays). The proposed approach has been applied to Spanish airports data for year 2008 comparing the computed directional distance efficiency scores with those obtained using a conventional, single-process directional distance function approach. From this comparison, it can be concluded that the proposed network DEA approach has more discriminatory power than its single-process counterpart, uncovering more inefficiencies and providing more valid results.     

Towards a better understanding of the cisplatin mode of action

We have studied how platinum(II) complexes [Pt(dien)Cl]Cl, [Pt(en)Cl2] and cisplatin react with hybrid molecules that contain sulfur and nitrogen ligands, in particular Phac-Met-linker-p5'dG (Phac = phenylacetyl), Phac-His-linker-p5'dG, Phac-His-Met-linker-p5'dG and Phac-His-Gly-Met-linker-p5'dCATGGCT. The progress of the reactions was monitored by HPLC, and by [1H,15N]-HSQC NMR when 15N-cisplatin was used. The products were isolated and characterised by using enzymatic and chemical reactions and spectroscopic techniques (UV and/or NMR spectroscopy, electrospray or MALDI-TOF mass spectrometry). The combined use of digestion with proteases and reaction with hydrogen peroxide followed by mass spectrometric analysis indicated the platinum coordination positions on the peptide moiety of the largest hybrid. Monofunctional Pt-S adducts were transformed into Pt-N complexes in which Pt-N7 bonds were formed preferentially. Most of the chelates isolated had Pt-S bonds, and, in the case of cisplatin complexes, loss of the ammine trans to sulfur gave rise to the formation of tricoordinate species with platinum-mediated peptide-nucleotide cross-links. 1,2-Intrachain platinum GpG adducts were only obtained in very small amounts (1-4%).     

Synthesis and Characterization of [(1,4‐diamine)dichloro]platinum(II) Compounds Preliminary Studies on their Biological Activity

Two 1,4‐diamine ligands were synthesized having 1,2‐bis(aminomethyl)‐cyclohexane and 1,2‐bis(aminomethyl)‐benzene structures. The two ligands have different electron density in the six‐membered ring: a cyclohexane versus a phenyl ring. The organic synthesis of the ligands was carried out by synthetic pathways of seven and four steps, respectively, starting from 1,2,3,6‐tetrahydrophthalic anhydride and diethyl phthalate. The coordination of platinum to these ligands afforded platinum(II) complexes which are analogue to the clinical drug cisplatin but form a seven‐membered chelate ring. The interaction of the platinum compounds with DNA was studied in order to know the relationship between the electron density of ligands and their capability to chelate DNA, by using three techniques: Circular Dichroism, Agarose Gel Electrophoresis and Atomic Force Microscopy. The degree of interaction of both compounds with DNA was slightly different, but both complexes showed a cisplatin‐like behaviour and are promising candidates to follow an extensive study of their cytotoxic activity.     

CZE separation of amitrol and triazine herbicides in environmental water samples with acid-assisted on-column preconcentration

A simple analytical scheme for the detection and quantification of amitrol and triazine herbicides (atrazine, ametryn and atraton) and degradation product (2‐hydroxyatrazine) in environmental water samples by CZE is reported. On‐column preconcentration of analytes from untreated water samples (mineral, spring, tap and river water) is accomplished by introducing an acid plug (200 mM citrate of pH 2.0) after the sample and then proceeding with the CZE separation, using 100 mM formiate buffer of pH 3.5 as running buffer and 25.0 KV as separation voltage. UV detection at 200 nm provides LODs from 50 to 300 nM in untreated samples and they were lowered tenfold by sample preconcentration by evaporation. Calculated recoveries were typically higher than 90%. Minimal detectable concentration of the electroactive amitrol could be decreased about 20‐fold when electrochemical detection was employed by monitoring the amperometric signal at +800 mV using a carbon paste electrode (LOD of 9.6 nM, 0.81 μg/L, versus 170 nM, 14.3 μg/L, using amperometric and UV detection, respectively) in untreated water samples.     

Interaction of a peptide from the pre-transmembrane domain of the severe acute respiratory syndrome coronavirus spike protein with phospholipid membranes

The severe acute respiratory syndrome coronavirus (SARS-CoV) envelope spike (S) glycoprotein, a Class I viral fusion protein, is responsible for the fusion between the membranes of the virus and the target cell. In order to gain new insight into the protein membrane alteration leading to the viral fusion mechanism, a peptide pertaining to the putative pre-transmembrane domain (PTM) of the S glycoprotein has been studied by infrared and fluorescence spectroscopies regarding its structure, its ability to induce membrane leakage, aggregation, and fusion, as well as its affinity toward specific phospholipids. We demonstrate that the SARS-CoV PTM peptide binds to and interacts with phospholipid model membranes, and, at the same time, it adopts different conformations when bound to membranes of different compositions. As it has been already suggested for other viral fusion proteins such as HIV gp41, the region of the SARS-CoV protein where the PTM peptide resides could be involved in the merging of the viral and target cell membranes working synergistically with other membrane-active regions of the SARS-CoV S glycoprotein to heighten the fusion process and therefore might be essential for the assistance and enhancement of the viral and cell fusion process.