Influence of Particle Size and Concentration on Rheological Behaviour of Reconstituted Apple Purees

This work investigates the impact of structural parameters on the rheological behaviour of apple purees. Reconstructed apple purees from 0 g/100 g up to 2.32 g/100 g of insoluble solids content and varying in particle size were prepared. Three different particle size distributions were obtained by mechanical treatment only, to modify both size and morphology of the particles without modifying the intrinsic rigidity of the cell walls. Rheological measurements showed that the insoluble solids content have a first order effect on the rheological behaviour of the suspensions: three concentrations domains were observed in both dynamic and flow measurements. A model is proposed for each domain. The existence of a weak network between particles is clearly shown over a critical concentration of insoluble solids (cell walls) depending on particle size distribution (semi-diluted domain). In a concentrated domain, particles are on close packing conditions and their apparent volume begin to shrink. Particle size and shape also play an important role on the rheological behaviour of reconstructed apple puree. Due to their irregular shape, cell clusters clog the medium at lower concentration compared to individual cells.     

Influence of Plasma Polymerized Dielectric Buffer Layer and Gold Film on the Excitation of Long-Range Surface Plasmon Resonance

Recently, long-range surface plasmon resonance (LRSPR) sensor has attracted a great deal of attention as a potentially non-destructive and label-free technique for cellular studies in real time. Thus, much effort has been placed on the fabrication and optimization of multilayered structure required for the excitation of LRSPR. In this work, a detailed study about the influence of both plasma polymerized dielectric buffer layer (DBL) and thin gold film on the excitation of LRSPR was performed. The DBLs of different thicknesses were deposited directly onto SF11 glass slides by radio frequency plasma polymerization (pp) of perfluorooctyl ethylene (PFOE). Thereafter, Au films of different thicknesses were thermally evaporated onto the ppPFOE layers. Atomic force microscopy (AFM) results suggest that the resulting SF11/ppPFOE/Au structure has a smooth surface regardless of Au film’s thickness. LRSPR measurements indicate that the excitation of LRSPR relies not only on the thickness of the ppPFOE buffer layer, but also on the thickness and optical property of thin Au film. Theoretical simulation based on Fresnel’s equation allows for the determination of both the thickness and optical constant of each layer supporting the LRSPR, and also enables us to predict the optimum combination of ppPFOE and Au film in a LRSPR sensor. The performance of various LRSPR sensors to monitor the bulk refractive index variation has also been investigated.     

The Plasmon–Plasmon Coupling in a System of a Dielectric Slab Doped with Silver Nano-spheres Sandwiched Between Two Silver Parallel Plates

I compute the transmission coefficient as function of the incident light frequency for a system consisting of a dielectric slab doped with silver nano-spheres sandwiched between two silver parallel plates. Then, I analyze the details of the transmission spectrum identifying the coupled plasmons from the two (doped dielectric and plates) subsystems which dominate the system’s dynamics.     

U-Shaped Photonic Crystal Fiber Based Surface Plasmon Resonance Sensors

A surface plasmon resonance sensor based on a U-shaped photonic crystal fiber with a rectangular lattice has been designed through finite element method. The U-shaped fiber exhibits not only stronger mechanical strength but also better sensor performance than our previous scheme. The upper detection limit extends to higher analyze refractive index, 1.384, for phase interrogation. We introduce a ratio to evaluate the impact of higher order plasmonic mode. For wavelength modulation scheme, the parameter to describe the performance of a sensor is chosen to be the figure of merit, which can be up to 533.8[RIU^?1] around complete coupling condition.     

Comprehensive Surface-Wave Description for the Nano-scale Energy Concentration with Resonant Dipole Antennas

Resonant optical dipole nano-antennas allow giant field enhancement within nano-gaps. To show how the energy of external illumination waves is delivered and concentrated in nano-gaps, we build up a model by considering the dynamical launching and multiple scattering processes of surface plasmon polaritions (SPPs) on both antenna arms. The model captures the main feature of the antenna resonance as evidenced by comparison of the model prediction with fully vectorial numerical results and provides an intuitive picture that the energy of external wave is initially transferred into SPP and is then coupled into the nano-gap. The enhanced field in the nano-gap oscillates quasi-periodically with the increase of the antenna-arm length, and the resonance peaks can be predicted with a phase-matching condition derived from the model, showing that antenna resonance is due to a constructive interference of the multiple-scattered SPPs. Analytical equation for determining the complex resonance wavelength and the quality factor of the resonant modes is obtained. The model however exhibits observable deviation from fully vectorial numerical results for the lowest resonance order (for antenna with the shortest arms), evidencing that, for this case, surface waves other than SPPs contribute to the antenna resonance. The present results are helpful for clarifying the underlying physics for the energy concentration with resonant dipole antennas and may provide recipes for intuitive design of antenna devices, such as those used for optical nonlinearity enhancement and biochemical sensing.     

Assessment of Blood Contamination in Biological Fluids Using MALDI-TOF MS

Biological fluid sample collection often includes the risk of blood contamination that may alter the proteomic profile of biological fluid. In proteomics studies, exclusion of contaminated samples is usually based on visual inspection and counting of red blood cells in the sample; analysis of specific blood derived proteins is less used. To fill the gap, we developed a fast and sensitive method for ascertainment of blood contamination in crude biological fluids, based on specific blood-derived protein, hemoglobin detection by MALDI-TOF MS. The MALDI-TOF MS based method allows detection of trace hemoglobin with the detection limit of 0.12 nM. UV-spectrometry, which was used as reference method, was found to be less sensitive. The main advantages of the presented method are that it is fast, effective, sensitive, requires very small sample amount and can be applied for detection of blood contamination in various biological fluids collected for proteomics studies. Method applicability was tested on human cerebrospinal and follicular fluid, which proteomes generally do not contain hemoglobin, however, which possess high risk for blood contamination. Present method successfully detected the blood contamination in 12 % of cerebrospinal fluid and 24 % of follicular fluid samples. High percentage of contaminated samples accentuates the need for initial inspection of proteomic samples to avoid incorrect results from blood proteome overlap.     

Calprotectin Pegylation Enhanced Its Physical and Structural Properties

Calprotectin is member of the S-100 protein family with a wide plethora of intra-and extracellular functions. Anticancer activities, antimicrobial effects and being a qualified disease marker are among the compelling features of this protein to be used as a pharmaceutical agent. However, there are several impediments to applications of protein pharmaceuticals including: proteolytic degradation, short circulating half-life, low solubility and immunogenicity. Pegylation is a common bioconjugation polymer capable of overcoming these drawbacks. Recombinant expression and purification of calprotectin along with its pegylation would result in enhanced pharmaco-dynamic and pharmacokinetic properties. Our florescence spectroscopy and far Ultraviolet-optical density results indicate that pegylation altered the physical and structural properties of the calprotectin to become in a more stable and functionally active state. Due to enhanced pharmacodynamic and pharmacokinetic properties of the calprotectin via pegylation, this study would pave the way for better in vitro and in vivo validations of calprotectin applications in medical practice.