Microscopical investigations of nisin-loaded nanoliposomes prepared by Mozafari method and their bacterial targeting

Nanoencapsulation may improve activity of protein or polypeptide antimicrobials against a variety of microorganisms. In this study, nanoliposomes prepared from different lipids (Phospholipon 90H, Phospholipon 100H, dipalmitoylphosphatidylcholine (DPPC), stearylamine (SA), dicetyl phosphate (DCP) and cholesterol) by a new, non-toxic and scalable method, were tested for their capacity to encapsulate nisin Z and target bacteria (Bacillus subtilis and Pseudomonas aeruginosa). Factors affecting the entrapment efficiency (charge and cholesterol concentration in the vesicles) and stability of nanoliposomes were assessed. The nanoliposomes and their bacterial targeting were visualised, using different microscopes under air and liquid environments. Nisin was entrapped in different nanoliposomes with encapsulation efficiencies (EE) ranging from 12% to 54%. Anionic vesicles possessed the highest EE for nisin while increase in cholesterol content in lipid membranes up to 20% molar ratio resulted in a reduction in EE. Stability of nanoliposome-encapsulated nisin was demonstrated for at least 14 months at 4 °C (DPPC:DCP:CHOL vesicles) and for 12 months at 25 °C (DPPC:SA:CHOL vesicles).     

Theory of molecular excitation and relaxation near a plasmonic device

The new optical concepts currently developed in the research field of plasmonics can have significant practical applications for integrated optical device miniaturization as well as for molecular sensing applications. Particularly, these new devices can offer interesting opportunities for optical addressing of quantum systems. In this article, we develop a realistic model able to explore the various functionalities of a plasmon device connected to a single fluorescing molecule. We show that this theoretical method provides a useful framework to understand how quantum and plasmonic entities interact in a small area. Thus, the fluorescence signal evolution from excitation control to relaxation control depending on the incident light power is clearly observed.     

Vibrational spectra of rhombohedral TeO3 compared to those of ReO3‐like proto‐phase and α‐TeO2 (paratellurite): lattice dynamic and crystal chemistry aspects

Vibrational spectra of rhombohedral TeO₃ (r‐TeO₃) are analyzed along with those of ReO₃‐like proto‐phase (c‐TeO₃) and α‐TeO₂ (paratellurite), emphasizing their lattice dynamic and crystal chemistry aspects. It is shown that (1) r‐TeO₃ can be regarded as resulting from the condensation of a particular R‐point soft phonon of c‐TeO₃; (2) the Raman spectra of r‐TeO₃ and α‐TeO₂ are indicative of the two fundamentally different (from the crystal chemistry point of view) types of crystalline oxides, namely, framework‐type and island‐type, respectively. Copyright © 2010 John Wiley & Sons, Ltd.     

Cutting‐edge mass spectrometry characterization of originator,biosimilar and biobetter antibodies

The approval process for antibody biosimilars relies primarily on comprehensive analytical data to establish comparability and high similarity with the originator. Mass spectrometry (MS) in combination with liquid chromatography (LC) and electrophoretic methods are the corner stone for comparability and biosimilarity evaluation. In this special feature we report head‐to‐head comparison of trastuzumab and cetuximab with corresponding biosimilar and biobetter candidates based on cutting‐edge mass spectrometry techniques such as native MS and ion‐mobility MS at different levels (top, middle and bottom). In addition, we discuss the advantages and the limitations of sample preparation and enzymatic digestion, middle‐up and ‐down strategies and the use of hydrogen/deuterium exchange followed by MS (HDX‐MS). Last but not least, emerging separation methods combined to MS such as capillary zone electrophoresis‐tandem MS (CESI‐MS/MS), electron transfer dissociation (ETD), top down‐sequencing (TDS) and high‐resolution MS (HR‐MS) that complete the panel of state‐of‐the‐art MS‐based options for comparability and biosimilarity evaluation are presented. Copyright © 2015 John Wiley & Sons, Ltd.     

Transmission of an obliquely incident beam of light through small apertures in a metal film

We recently found that the intensity of the electric near field of a triangular aperture in a metal film is strongly localized at one edge of the aperture for incident light polarized perpendicular to this edge. Previous numerical calculations of the near field of a triangular aperture in a planar metal film, using the field susceptibility technique, yielded a nearly quantitative agreement with the experiments. Using this numerical technique, we have investigated the influence of an obliquely incident plane wave on the near field of small circular and triangular apertures. An interpretation of the numerical results leads to a deeper understanding of the way in which light transmission through the aperture is excited. The data suggest that after excitation of currents in the metal film by the incident light, a scattering of these currents by the aperture generates the near field of the aperture. We found that the excitation of small apertures (size <100 nm) is due to a tangential magnetic field whereas the perpendicular electric field plays no role. The excitation of a small aperture can thus be described exclusively by a magnetic polarizability. We found that for thin metal films an interference of the scattered field with the field transmitted through the metal film changes the near field pattern. PACS 41.20.-q; 42.79.Ag; 68.37.Uv; 78.67.-n     

Studies on the drift properties and spatial resolution using a microMEGAS-equipped time projection chamber

R&D studies on the performance as well as on the gas properties of the microMEGAS-based time projection chamber with standard readout were carried out in June 2005 using 4 GeV/c pion beam in a magnetic field from 0 to 1 T at the proton synchrotron beam line at KEK, Japan. Analysis of the electron drift velocity, diffusion constant and point resolution of padrow measurement for MicroMEGAS TPC filled with 95% argon and 5% isobutane gas are presented. The underlying physical mechanism which determines the optimal TPC performance are briefly discussed. Preliminary measurements of gas properties and spatial resolution in close agreement with the analytical calculation and MAGBOLTZ simulation are summarized and presented in this paper.      

Optical analogy to electronic quantum corrals

We describe full multiple-scattering calculations of localized surface photonic states set up by lithographically designed nanostructures made of a finite number of dielectric pads deposited on a planar surface. The method is based on a numerical solution of the dyadic Dyson's equation. When the pads are arranged to form a closed circle, we find field patterns that look like the electronic charge density recently observed above quantum corrals. We propose two experimental techniques that could be used to observe these electromagnetic modes in direct space.     

Observation of the muonic decay of the charged intermediate vector boson

Muons of high transverse momentum p^μ_T have been observed in the large drift chambers surrounding the UA1 detector at the CERN 540 GeV pp? collider. For an integrated luminosity of 108 nb^?1, 14 isolated muons have been found with p_T > 15 GeV/c. They are correlated with a large imbalance in total transverse energy, and show a kinematic behaviour consistent with the muonic decay of the Intermediate Vector Boson W^± of weak interactions. The partial cross section is in agreement with previous measurements for electronic decays and with muon-electron universality. The W mass is determined to be m_W = 81⁺⁶_?7 GeV/c².     

Combined limits on the number of light neutrinos and the top mass from the measurement ofR=σ(W→ℓv)/σ(Z→ℓℓ)

Using the recent measurement of the ratio ofW→?v toZ→?? partial production cross-sections by UA1 and UA2, we derive an upper limit on the number of neutrinos and on the top quark mass, in the framework of the minimal standard model. To reduce the uncertainty on these limits, we use the most recent determination of sin² θ _w and the latest measurements of the structure functions by muon deep-inelastic experiments. No limit onm _top is obtained in the case of three neutrino families at the 95% C.L., while a fourth generation is excluded at this confidence level if the top mass is higher thanM _w ?m _b and if there is no new heavy lepton contribution in theW decay. The implications of light fourth generationb' andL are also investigated.     

Energy transfer in near-field optics

When the probe tip of a near-field optical microscope illuminates nanoparticles with marked absorption bands, a large number of photons are absorbed before reaching the detector. These energy losses enhance the dark contrast usually observed in the vicinity of metallic nanoparticles. We demonstrate theoretically that this phenomenon can be exploited to image, in the optical frequency range, dissipative domains with a nanometer scale resolution. Simulations performed with noble-metal particles indicate that the detected signal significantly drops down when the excitation frequency is approaching the plasmon resonance of the particles.