Precursor system of liquid crystalline phase containing propolis microparticles for the treatment of periodontal disease: development and characterization

Precursor systems of liquid crystalline phase were prepared using the surfactant PPG-5-Ceteth-20, isopropyl myristate, and water; gelatin microparticles containing propolis were then added into these systems. Homogeneity of dispersion, the in-system microparticle morphology, and sedimentation behavior of each formulation were evaluated. The rheological and mechanical properties (hardness, compressibility, and adhesiveness), the work of syringing, and the propolis release profile were also evaluated. All the formulations exhibited pseudoplastic flow and thixotropy, and they displayed storage modulus, loss modulus, dynamic viscosity, and loss tangent that depended on temperature, frequency, and composition. Mechanical properties varied significantly among the formulations being affected by changes in the composition and temperature. Raising the concentration of surfactant and adding propolis microparticles significantly decreased the work of syringing. The drug release was non-Fickian (anomalous) and there was no significant difference between the tested systems in the times required for 10%, 30%, and 50% release of the initial drug loading.     

Photocatalytic Oxidation of Organic Micro-Pollutants: Pilot Plant Investigation and Mechanistic Aspects of the Degradation Reaction

An innovative pilot plant based on UVB and TiO₂ (Anatase) allowed for photocatalytic degradation of organic micro-pollutants. The catalyst was immobilized onto a channel through which the solution containing a target molecule (methylene blue, MB) was re-circulated. Due to the cationic nature of the MB substrate, the adsorption reaction onto the catalyst surface provided a significant contribution to the overall degradation mechanism due to the negatively charged surface at neutral pH (TiO₂ pH_zpc = 6.8). The influence of the initial MB concentration was investigated in the range 0.3–2.0 mg L^?1 with the Langmuir–Hinshelwood (LH) model showing good data correlations at concentrations up to 0.7 mg L^?1, whereas at higher concentrations a pure zero-order (catalytic) kinetic trend was observed. Flow rate of the re-circulating solution sensibly influenced kinetics after the larger volumes of liquid exposed to UVB/TiO₂ and to the better oxygen saturation in the liquid phase. UV?vis and HPLC-MS/MS experimental determinations allowed for identification of MB residual concentration and by-products.     

Optical switching of a photochromic bis-phenylazo compound in PMMA films

We present our results on a newly synthesized bis-phenylazo derivative, namely bisperfluoroalkylsulfonylamino- arylazomethylene-triphenyl-phosphorane (BAM-TPP). Thin films of BAM-TPP in polymethylmethacrylate (PMMA) matrix were prepared. The films (thickness, d < 60 μm) were exposed to UV-vis light with variable intensity in order to stimulate the photochromic reaction of BAM-TPP. The resulting absorption changes of the BAM-TPP/PMMA films were investigated by spectrophotometry. The absorption spectra reveal that BAM-TPP molecules in PMMA undergo photoisomerization with resulting decrease of absorbance in the range 500–700 nm. Finally, the time response of film transmittance at 514 nm under increasing CW light intensity was recorded, showing that the reverse photochromic process brings the absorbance back to its pristine value. The obtained films thus proved to be suitable for optical switching applications.

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Determination of the conformation of the human VDAC1 N-terminal peptide, a protein moiety essential for the functional properties of the pore

Mitochondrial porin or VDAC (voltage-dependent anion-selective channel) is the most abundant protein in the mitochondrial outer membrane. The structure of VDAC has been predicted to be a transmembrane beta-barrel with an alpha-helix at the N terminus. It is a matter of debate as to whether this putative alpha-helix plays a structural role as a component of the pore walls or a function in the pore activity. We have synthesised the human VDAC1 (HVDAC1) N-terminal peptide Ac-AVPPTYADLGKSARDVFTK-NH2 (Prn2-20) and determined its structure by CD and NMR spectroscopy. CD studies show that the Prn2-20 peptide exists in aqueous solvent as an unstructured peptide with no stable secondary structure. In membrane-mimetic SDS micelles or water/trifluoroethanol, however, it assumes an amphipathic alpha-helix conformation between Tyr5 and Val16, as deduced from NMR. No ordered structure was observed in dodecyl beta-maltoside. Differential scanning calorimetric measurements were carried out in order to examine the membrane affinity of the peptide. Upon interaction with the negatively charged 1,2 dipalmitoyl-sn-glycero-3-phosphoserine membrane, Prn2-20 exhibited distinctive behaviour, suggesting that electrostatics play an important role. Interaction between the peptide and artificial bilayers indicates that the peptide lies on the membrane surface. Recombinant HVDAC1 deletion mutants, devoid of seven or 19 N-terminal amino acids, were used for transfection of eukaryotic cells. Over-expression of HVDAC1 increases the number of Cos cells with depolarised mitochondria, and this effect is progressively reduced in cells transfected with HVDAC1 lacking those seven or 19 amino acids. The mitochondrial targeting of the deletion mutants is unaffected. The overall picture emerging from our experiments is that the VDAC N-terminal peptide plays a role in the proper function of this protein during apoptotic events.     

Sequential Data Fusion via Vector Spaces: Fusion of Heterogeneous Data in the Complex Domain

A sequential data fusion approach via higher dimensional vector spaces is introduced. This is achieved by making use of the representation of directional signals within the field of complex numbers $C$ . The concept of data fusion is next introduced and the place of the proposed approach within that framework is identified. The benefits of such an approach are illustrated and a range of possible applications is shown. The concept introduced is supported by a real world case study which focuses on simultaneous forecasting of wind speed and direction. The architectures and learning algorithms which support this concept are introduced and their distributed sequential fusion nature is highlighted.     

Asymptotically stable visual servoing of manipulators via neural networks

In this article we present a class of position control schemes for robot manipulators based on feedback of visual information processed through artificial neural networks. We exploit the approximation capabilities of neural networks to avoid the computation of the robot inverse kinematics as well as the inverse task space–camera mapping which involves tedious calibration procedures. Our main stability result establishes rigorously that in spite of the neural network giving an approximation of these mappings, the closed‐loop system including the robot nonlinear dynamics is locally asymptotically stable provided that the Jacobian of the neural network is nonsingular. The feasibility of the proposed neural controller is illustrated through experiments on a planar robot. © 2000 John Wiley & Sons, Inc.     

Reduction of vibrations in blanking by MR dampers

The break through shock during sheet metal blanking operations generates uncontrolled high reverse loads, mechanical vibrations and loud noise that may cause problems such as fatigue cracks in the press components, premature wear in tooling and great discomfort for press operators.In this paper, the application of magneto-rheological (MR) dampers to reduce the shock response of press systems is considered with the aim of evaluating, through full-scale experiments, feasibility and practicability of their implementation and understanding the potential benefits in comparison with conventional dampers.     

Foam‐Mat Freeze‐Drying of Bifidobacterium longum RO175: Viability and Refrigerated Storage Stability

Foaming as a pretreatment was used prior to freeze‐drying of Bifidobacterium longum RO175 to investigate the potential acceleration of the drying rate and increase in microorganism viability after the process. A study on storage of foamed and nonfoamed freeze‐dried products at 4 °C completed this study. B. longum RO175 in foamed medium could be freeze‐dried in 1/7 to 1/4 of the time required for nonfoamed suspensions. In addition, foamed suspensions presented higher viability immediately after freeze‐drying (13.6% compared to 12.81 % or 11.46%, depending on the cryoprotective media). Refrigerated storage led to a reduction in B. longum RO175 viability for all tested protective agents (foamed and nonfoamed). No correlation between glass transition temperature and stability of probiotic powders was observed during storage. In addition, lower viability after 56 d of storage was observed for foamed materials, probably due to foam porous structure and higher hygroscopicity, and oxygen presence and moisture pickup during storage.