A novel application of electrospinning technique in sublingual membrane: characterization,permeation and in vivo study

Isosorbide dinitrate–polyvinylpyrrolidone (ISDN–PVP) electrospinning fibers were formulated and explored as potentially sublingual membrane. The addition of polyethylene glycol (PEG) to the formulation improved flexibility and reduced fluffiness of the fiber mat. The scanning electron microscopy (SEM) demonstrated that the fibers tended to be cross-linking, and the crosslinking degree increased with the increase of PEG amount. The differential scanning calorimetry (DSC) indicated that ISDN existed in non-crystalline state in the fibers (except at the highest drug content). The infrared spectroscopy suggested that ISDN had better compatibility with the ingredients owing to the hydrogen bonding (or hydrophobic interactions). The fibers were highly favorable for the fabrication of sublingual membrane due to neutral pH, large folding endurance and rapid drug release (complete dissolution within 120 s). The permeation study of ISDN through both dialysis membrane (DM) and porcine sublingual mucosa (SM) were carried out. A significant relationship of drug permeation rate through DM and SM was built up, which indicated that DM could be used to partly simulate SM and assess formulation. The pharmacokinetic study in rats demonstrated that the electrospinning fiber membrane had a higher C_max and lower T_max compared to the reference preparation, and the relative bioavailability of the fiber membrane was 151.6%.     

Simple and sensitive HPLC method with fluorescence detection for the measurement of ibuprofen in rat plasma: application to a long-lasting dosage form

A simple and sensitive high-performance liquid chromatography (HPLC) assay applied to the measurement of ibuprofen in rat plasma has been developed. Two parameters have been investigated to improve ibuprofen detectability using fluorescence detection: variation of mobile phase pH and the use of beta-cyclodextrin (beta-CD). Increasing the pH value from 2.5 to 6.5 and adding 5 mM beta-CD enhanced the fluorescence signal (lambda(exc) = 224 nm; lambda(em) = 290 nm) by 2.5 and 1.3-fold, respectively, when using standards. In the case of plasma samples, only pH variation significantly lowered detection and quantification limits, down to 10 and 35 ng/mL, respectively. Full selectivity was obtained with a single step for plasma treatment, that is, protein precipitation with acidified acetonitrile. The validated method was applied to a pharmacokinetic study of ibuprofen encapsulated in microspheres and subcutaneously administered to rats.     

Thermogravimetric method for determination of oxygen stoichiometry in superconducting 1:2:3 and metal-substituted 1:2:3 compounds

The paper presents a modified thermogravimetric method for determination of oxygen stoichiometry of the oxide superconductors YBa₂Cu₃O_7−δ and metal-substituted compounds of the type YBa_2−x La _x Cu₃O_7+δ and YBa₂(Cu_1−x M _x )₃O_7−δ (M=Mg/Zn) between 25° and 930°C.     

Development of a selective and sensitive flotation method for determination of trace amounts of cobalt, nickel, copper and iron in environmental samples

A simple, selective and rapid flotation method for the separation-preconcentration of trace amounts of cobalt, nickel, iron and copper ions using phenyl 2-pyridyl ketone oxime (PPKO) has been developed prior to their flame atomic absorption spectrometric determinations. The influence of pH, amount of PPKO as collector, type and amount of eluting agent, type and amount of surfactant as floating agent and ionic strength was evaluated on the recoveries of analytes. The influences of the concomitant ions on the recoveries of the analyte ions were also examined. The enrichment factor was 93. The detection limits based on 3 sigma for Cu, Ni, Co and Fe were 0.7, 0.7, 0.8, and 0.7 ng mL(-1), respectively. The method has been successfully applied for determination of trace amounts of ions in various real samples.     

Forces in piles of granular material: an analytic and 3D DEM study

We investigate the stress distribution at the base of a conical sandpile using both analytic calculations and a three dimensional discrete element code. In particular, we study how a minimum in the normal stress can occur under the highest part of the sandpile. It is found that piles composed of particles with the same size do not show a minimum in the normal stress. A stress minimum is only observed when the piles are composed of particles with different sizes, where the particles are size segregated in an ordered, symmetric, circular fashion, around the central axis of the sandpile. If a pile is composed of particles with different sizes, where the particles are randomly distributed throughout the pile, then no stress dip is observed. These results suggest that the stress dip is due to ordered, force contacts between equiheight particles which direct stress to the outer parts of the pile. Received: 14 June 2000     

A stabilized mixed finite element method for shear-rate dependent non-Newtonian fluids: 3D benchmark problems and application to blood flow in bifurcating arteries

This paper presents a stabilized mixed finite element method for shear-rate dependent fluids. The nonlinear viscosity field is a function of the shear-rate and varies uniformly in space and in time. The stabilized form is developed via application of Variational Multiscale (VMS) framework to the underlying generalized Navier–Stokes equation. Linear and quadratic tetrahedral and hexahedral elements are employed with equal-order interpolations for the velocity and pressure fields. A variety of benchmark problems are solved to assess the stability and accuracy properties of the resulting method. The method is then applied to non-Newtonian shear-rate dependent flows in bifurcating artery geometry, and significant non-Newtonian fluid effects are observed. A comparative study of the proposed method shows that the additional computational costs due to the nonlinear shear-rate dependent viscosity are only ten percent more than the computational cost for a Newtonian model.     

3D printing in X-ray and Gamma-Ray Imaging: A novel method for fabricating high-density imaging apertures

Advances in 3D rapid-prototyping printers, 3D modeling software, and casting techniques allow for cost-effective fabrication of custom components in gamma-ray and X-ray imaging systems. Applications extend to new fabrication methods for custom collimators, pinholes, calibration and resolution phantoms, mounting and shielding components, and imaging apertures. Details of the fabrication process for these components, specifically the 3D printing process, cold casting with a tungsten epoxy, and lost-wax casting in platinum are presented.     

An improved prediction of the human in vivo intestinal permeability and BCS class of drugs using the in vitro permeability ratio obtained for rat intestine using an Ussing chamber system

The Biopharmaceutics Classification System (BCS) was developed to facilitate estimation of the in vivo pharmacokinetic performance of drugs from human intestinal permeability and solubility. However, the measurement of human in vivo intestinal permeability, unlike that of solubility, is problematic and inefficient. Thus, rat in vitro intestinal permeability results obtained via the Ussing chamber technique are often used instead. However, these data could be unreliable due to difficulty in maintaining the viability of the dissected intestinal membrane in the Ussing chamber. Therefore, a more efficient method to obtain a reliable in vitro permeability is mandatory. Here, we propose a new approach by introducing a novel factor called the permeability ratio (PR). Basically, PR is a rat in vitro intestinal permeability obtained from the Ussing chamber, which is then corrected by the permeability of lucifer yellow, a paracellular permeability marker. To prove the validity of the method, 12 model drugs representing different BCS classes were tested, and the correlation with human in vivo intestinal permeability was high. More importantly, the new method perfectly classified all 12 model drugs. The results indicate that PR is a reliable factor with high correlation to human in vivo intestinal permeability, which can further be used to accurately predict the BCS classification.     

3D laser ultramicroscopy: A method for nondestructive characterization of micro- and nanoinclusions in high-purity materials for fiber and power optics

This paper describes a 3D laser ultramicroscopy technique and apparatus for the nondestructive characterization of heterophase inclusions in bulk high-purity materials for fiber and power optics. In this technique, the concentration and size of inclusions undetectable by optical microscopy are determined using CCD detection of the light scattered by them in a direction normal to the incident laser beam at wavelengths from 0.63 to 0.98 μm. The detection limit of the technique in terms of inclusion size is n × (10–100) nm, the range of detectable number concentrations is 1–10¹¹ cm^?3, and the scan depth in the sample is ～1 cm. Its performance has been evaluated using test systems. The potential of the technique is illustrated by the dispersion analysis of promising materials for IR fiber-optic applications.     

A new HPLC approach for the determination of hydrophilic and hydrophobic components: the case of pseudoephedrine sulfate and loratadine in tablets

Effective isocratic separations of decongestants and antihistamines is a challenging analytical task due to wild differences in their lipohilicities (hydrophilic decongestants and hydrophobic antihistamines). In this paper a new approach for resolving such a problem is described taking pseudoephedrine sulfate and loratadine as an example. The chromatographic behavior of pseudoephedrine sulfate and loratadine on RP C18 and C8 columns were studied in presence and absence of sodium lauryl sulfate (SLS). The effect of combining two different types of stationary phases (cyano and C18 or C8) on the relative retention of the two compounds was investigated. In conclusion, it was found that the combination of a C18 column followed by a standard cyano column provides a stationary phase that separates both compounds effectively and within a reasonable time. This approach was compared to a literature method and demonstrated to have superior selectivity.     

Moisture Absorption and Desorption in an Ionomer-Based Encapsulant: A Type of Self-Breathing Encapsulant for CIGS Thin-Film PV Modules

As an alternative to conventional encapsulation concepts for a double glass photovoltaic (PV) module, we introduce an innovative ionomer-based multi-layer encapsulant, by which the application of additional edge sealing to prevent moisture penetration is not required. The spontaneous moisture absorption and desorption of this encapsulant and its raw materials, poly (ethylene-co-acrylic acid) and an ionomer, are analyzed under different climatic conditions in this work. The relative air humidity is thermodynamically the driving force for these inverse processes and determines the corresponding equilibrium moisture content (EMC). Higher air humidity results in a larger EMC. The homogenization of the absorbed water molecules is a diffusion-controlled process, in which temperature plays a dominant role. Nevertheless, the diffusion coefficient at a higher temperature is still relatively low. Hence, under normal climatic conditions for the application of PV modules, we believe that the investigated ionomer-based encapsulant can “breathe” the humidity: During the day, when there is higher relative humidity, it “inhales” (absorbs) moisture and restrains it within the outer edge of the module; then at night, when there is a lower relative humidity, it “exhales” (desorbs) the moisture. In this way, the encapsulant protects the cell from moisture ingress.     

Design and realisation of an efficient environmental assessment method for 3R systems: a case study on engine remanufacturing

Recently, the manufacturing industry has been striving for sustainability because of the environmental degradation and resource depletion caused by it. Remanufacturing considerably saves material and is energy efficient, and thus, it can represent an important solution to environmental issues. However, the uncertainty of remanufacturing makes the practical management of closed-loop supply chains (CLSCs) difficult. To unlock the value potential of end-of-life (EOL) products, we studied a reuse, remanufacture, and recycle (3R) processing system under quality uncertainty for returned EOL engines. In the system, the returned cores were distributed into different processing routes, depending on the results of quality grading. The proposed matrix operations could efficiently assess the environmental benefits; moreover, we designed an algorithm to calculate the quality coefficient that reflects the overall quality condition of returned EOL cores. The impacts of quality uncertainty on the environment could be efficiently quantified via our proposed method. Furthermore, using Monte Carlo simulation and the law of large numbers, we devised a model to establish direct and definite quantitative relationships between the quality coefficient and production indexes. This model provides a basis for the formulation of optimal acquisition strategies under different returning scenarios.     

A multiresolution‐based method for the determination of the relative resolution between images: First application to remote sensing and medical images

Spatial resolution is a key parameter of all kind of images. This is of particular importance in fields as, for example, medicine or remote sensing. The nominal resolution of a positron emission tomography (PET) or nuclear magnetic resonance (NMR) scanners are directly related to the size, number, and position of the detectors in the scanner ring. Also, the nominal spatial resolution of the remote sensing satellites is a well‐known characteristic because it is directly related to the area in ground that represents a pixel in the detector. Nevertheless, in practice, the actual resolution of a medical scanner image or of an image obtained from a satellite is difficult to know precisely because it depends of many other factors. However, if we have two or more images of the same region of interest, obtained using similar or different instruments, it is possible to compare the relative resolution between them. In this paper we propose a wavelet‐decomposition‐based method for the determination of the relative resolution between two images of the same area. The method can be applied, in principle, to any kind of images. As example, we applied the method to pairs of remote sensing and medical images. In the case of remote sensing, we computed the relative resolution between SPOT‐3, LANDSAT‐5 and LANDSAT‐7 panchromatic and multispectral images taken under similar as well as under very different conditions. In the case of medical imaging, we computed the relative resolution between a pair of simultaneously obtained PET and NMR images of the same object. On the other hand, if we know the true absolute resolution of one of the images of the pair, we can compute the resolution of the other. Thus, in the last part of this paper, we describe a spatial calibrator that we have designed and constructed to help compute the absolute resolution of a single remotely sensed image, presenting an example of its use. © 2006 Wiley Periodicals, Inc. Int J Imaging Syst Technol, 15, 225–235, 2005     

Effects of coating layer and release medium on release profile from coated capsules with Eudragit FS 30D: an in vitro and in vivo study

The aim of the present research was to evaluate the impact of coating layers on release profile from enteric coated dosage forms. Capsules were coated with Eudragit FS 30D using dipping method. The drug profile was evaluated in both phosphate buffer and Hank’s solutions. Utilization X-ray imaging, gastrointestinal transmission of enteric coated capsules was traced in rats. According to the results, no release of the drug was found at pH 1.2, and the extent of release drug in pH 6.8 medium was decreased by adding the coating layers. The results indicated single-layer coated capsules in phosphate buffer were significantly higher than that in Hank’s solution. However, no significant difference was observed from capsules with three coating layers in two different dissolution media. X-ray imaging showed that enteric coated capsules were intact in the stomach and in the small intestine, while disintegrated in the colon.     

3D simulation of nano/micro cellulose delivery systems for dermic and respiratory applications: Case study of eucalyptus essential oil incorporation

The purpose of this work was to design, develop and optimize different combinations of drug delivery systems (DDS) with nanofibrillated (NFC) and microfibrillated (MFC) cellulose-based materials, as 3D networks, encapsulating eucalyptus essential oil molecules, for dermic and respiratory applications. Experimental and computational approaches were implemented for characterization, modeling studies, and structure porosity optimization. The optimized porous structures were able to retain the desired molecules, resulting in more controlled and uniform release kinetics over time. This methodology allowed for optimizing new bio-based drug delivery systems with controlled porosity, pore dimension and distribution, retention of therapeutic molecules, and uniformity of the 3D network. The results showed that different drug delivery systems with this 3D matrix released the essential oil molecules, improving its stability and prolonging the exposure time, factors that are important to develop promising drug delivery systems in biomaterials fields. Overall, cellulose-based structured biomaterials capable of transporting and releasing essential oil components are representatives of innovative materials that will be used in novel applications, in which the exposure time to the therapeutic molecules constitutes a competitive benefit.     

Synthesis and application of chloromethylated polystyrene modified with 1-phenyl-1,2-propanedione-2-oxime thiosemicarbazone (PPDOT) as a new sorbent for the on-line preconcentration and determination of copper in water, soil, and food samples by FAAS

In this paper, we report a simple and sensitive on-line solid phase extraction system for the preconcentration and determination of Cu(II) by flame atomic absorption spectrometry (FAAS). This method is based upon the on-line retention of copper at pH 5.0 on a minicolumn packed with chloromethylated polystyrene modified by 1-phenyl-1,2-propanedione-2-oxime thiosemicarbazone (PPDOT) as a new solid-phase extraction (SPE) sorbent. The retained Cu(II) ions were eluted with 1.0 M HNO₃, and transported directly to FAAS for determination. Several chemical and flow variables were studied and optimized for a quantitative preconcentration and determination of copper(II). At the optimized conditions, for preconcentration of 10.0 mL of a sample solution, a linear calibration graph was obtained over the concentration range of 3.00-120.0 μg L⁻¹ for Cu(II). The limit of detection (3σ), limit of quantification (10σ), and enrichment factor are 0.56 μg L⁻¹, 2.0 μg L⁻¹ and 41, respectively. The relative standard deviation (n = 6) at 20 μg L⁻¹ of Cu(II) is 2.0%. This method could be applied for determination of trace amounts of Cu(II) in water, soil, and food samples with satisfactory results.     

A route toward the development of 3D magnetic scaffolds with tailored mechanical and morphological properties for hard tissue regeneration: Preliminary study

A basic approach toward the design of three-dimensional (3D) rapid prototyped magnetic scaffolds for hard-tissue regeneration has been proposed. In particular, 3D scaffolds consisting of a poly(ε-caprolactone) (PCL) matrix and iron oxide (Fe₃O₄) or iron-doped hydroxyapatite (FeHA) nanoparticles were fabricated through a 3D fibre deposition technique. As a first approach, a polymer to nanoparticle weight ratio of 90/10 (wt/wt) was used. The effect of the inclusion of both kinds of nanoparticles on the mechanical, magnetic, and biological performances of the scaffolds was studied. The inclusion of Fe₃O₄ and FeHA nanoparticles generally improves the modulus and the yield stress of the fibres if compared to those of neat PCL, as well as the modulus of the scaffolds. Micro-computed tomography has confirmed the possibility to design morphologically-controlled structures with a fully interconnected pore network. Magnetisation analyses performed at 37°C have highlighted M-H curves that are not hysteretic; values of saturation magnetisation (M_s) of about 3.9 emu/g and 0.2 emu/g have been evaluated for PCL/Fe₃O₄ and PCL/FeHA scaffolds, respectively. Furthermore, results from confocal laser scanning microscopy (CLSM) carried out on cell-scaffold constructs have evidenced that human mesenchymal stem cells (hMSCs) better adhered and were well spread on the PCL/Fe₃O₄ and PCL/FeHA nanocomposite scaffolds in comparison with the PCL structures.