Mechanical properties of short fiber reinforced thermoplastic blends

An immiscible thermoplastic component was added to a conventional short fiber reinforced polymer to study its effect on the mechanical properties of the composite. Because of the preferential wetting of the fiber reinforcement a continuous network was formed of fibers ‘welded’ together by the minor component within the matrix polymer.Polyethylene (PE) was used as the matrix, polyamide-6 (PA6) as dispersed polymer phase and glass fibers (GF) as reinforcement. The obtained composite retained unusually high values of the elasticity modulus at temperatures above the melting point of the matrix. The upper limit of the ‘applicability’ of the material is determined by the melting point of the minor component. A simple model was derived to describe the mechanical properties of the composite. The model shows a good agreement with the experimental data. The influence of the model parameters on the predictions of the model was examined.     

Radio-Frequency Heating Kinetics of Softwood Logs

The project assessed the radio-frequency (RF) heating characteristics of logs of two softwood species, namely, Engelmann spruce (Picea spp.) and subalpine fir (Abies lasiocarpa). Sixty logs, equally divided between the two species, were RF heated in two different circumstances—with or without bark—until the temperature sensor from a number of those scattered within each specimen with the lowest reading indicated 70°C. Both species heated in short periods of time (～60 min), regardless of bark presence or absence, with relatively small energy requirements and without noticeable negative consequences on quality. The sapwood heated up faster, thus reaching higher temperatures because of its high moisture content and better complex permittivity values. Between the two tested species, fir is more prone to RF heating due to its higher ability to convert an electric field into heat.     

Diosgenin-selective molecularly imprinted pearls prepared by wet phase inversion

Functional poly(acrylonitrile-co-acrylic acid) imprinted pearls, selective for diosgenin – a steroidal saponin with the ability to reduce cholesterol from blood – were prepared by wet phase inversion. Three copolymers with the monomer ratios AN:AA90:10, 80:20, and 70:30 where used to prepare the corresponding MIPs (molecularly imprinted polymers) and NIPs (non-imprinted polymers).The rheology studies showed that an 8 w% solution of copolymer in dimethylformamide lead fastest to robust, spherical pearls. Affinity centres were generated via non-covalent bonding between diosgenin’s hydroxyl groups and carboxyl moieties of the copolymer matrix. The presence and the quality of the selective binding sites in MIPs were highlighted by optic and electronic microscopy, infrared spectroscopy, thermal analyses, and batch rebinding tests. The imprinting factor (IF) values, ranging from 1.9 to 4.35, decrease with the increasing of the initial concentration of feed solution. When comparing the MIPs concerning the AN:AA ratio, the IF decreases in the order AN:AA80:20 > AN:AA70:30 > AN:AA90:10, suggesting that the 80:20 ratio is the optimum compromise between selectivity (given by AA) and resistance (given by AN). For the best imprinted MIP, 80:20, affinity tests were performed with three competitors, obtaining the average affinity 54%, compared with 31%, 11%, and 4% for the competitors.     

Radiopaque acrylic bone cements with bromine‐containing monomer

One important issue for the acrylic bone cements concerns the radiopacity, which may be achieved by different ways. In this work, a new bromine‐containing acrylic monomer, the 2‐(2‐bromopropionyloxy) propyl methacrylate (BPPM), was synthesized and proposed to be used for providing radiopaque bone cements. Different acrylic bone cements were realized by partially replacing the methyl methacrylate (MMA) monomer phase with 5–20% w/w of BPPM‐comonomer. The effect of this comonomer on the curing parameters of acrylic bone cements, on their thermal and rheological properties, water absorption, density, contact angle, compression tests, and radiopacity was studied. It appears that the presence of BPPM does provide radiopacity, improves the curing parameters by decreasing the maximum curing temperature and increasing the setting time. The new BPPM‐acrylic bone cements exhibit lower glass transition temperature and better thermal stability when compared with the classical radiolucent acrylic cements. Rheological measurements have shown that 10–20% w/w of BPPM in the liquid phase of acrylic bone cement formulations increase its flexibility, and may also induce a slight crosslinking reaction during the curing phase. BPPM‐modified acrylic bone cements present lower polymerization shrinkage and higher compression strength, and similar water uptake, porosity, and water contact angle as the radiolucent PMMA‐cements. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

From Pathogenesis to Therapy in Knee Osteoarthritis: Bench-to-Bedside

Osteoarthritis (OA) is currently the most widespread musculoskeletal condition and primarily affects weight-bearing joints such as the knees and hips. Importantly, knee OA remains a multifactorial whole-joint disease, the appearance and progression of which involves the alteration of articular cartilage as well as the synovium, subchondral bone, ligaments, and muscles through intricate pathomechanisms. Whereas it was initially depicted as a predominantly aging-related and mechanically driven condition given its clear association with old age, high body mass index (BMI), and joint malalignment, more recent research identified and described a plethora of further factors contributing to knee OA pathogenesis. However, the pathogenic intricacies between the molecular pathways involved in OA prompted the study of certain drugs for more than one therapeutic target (amelioration of cartilage and bone changes, and synovial inflammation). Most clinical studies regarding knee OA focus mainly on improvement in pain and joint function and thus do not provide sufficient evidence on the possible disease-modifying properties of the tested drugs. Currently, there is an unmet need for further research regarding OA pathogenesis as well as the introduction and exhaustive testing of potential disease-modifying pharmacotherapies in order to structure an effective treatment plan for these patients.     

EURAMET.T-K7 Key Comparison of Water Triple-Point Cells

The results of a EURAMET key comparison of water triple-point cells (EURAMET.T-K7) are reported. The equipment used, the measuring conditions applied, and the procedures adopted for the water triple-point measurement at the participating laboratories are synthetically presented. The definitions of the national reference for the water triple-point temperature adopted by each laboratory are disclosed. The multiplicity of degrees of equivalence arising for the linking laboratories with respect to the ??mother?? comparison CCT-K7 is discussed in detail.     

Characterisation of silicon carbide films deposited by plasma-enhanced chemical vapour deposition

The paper presents a characterisation of amorphous silicon carbide films deposited in plasma-enhanced chemical vapour deposition (PECVD) reactors for MEMS applications. The main parameter was optimised in order to achieve a low stress and high deposition rate. We noticed that the high frequency mode (13.56 MHz) gives a low stress value which can be tuned from tensile to compressive by selecting the correct power. The low frequency mode (380 kHz) generates high compressive stress (around 500 MPa) due to ion bombardment and, as a result, densification of the layer achieved. Temperature can decrease the compressive value of the stress (due to annealing effect). A low etching rate of the amorphous silicon carbide layer was noticed for wet etching in KOH 30% at 80 °C (around 13 A/min) while in HF 49% the layer is practically inert. A very slow etching rate of amorphous silicon carbide layer in XeF₂ -7 A/min- was observed. The paper presents an example of this application: PECVD-amorphous silicon carbide cantilevers fabricated using surface micromachining by dry-released technique in XeF₂.     

Photodegradation process of Eosin Y using ZnO/SnO2 nanocomposites as photocatalysts: experimental study and neural network modeling

A series of coupled ZnO/SnO₂ nanocomposites were prepared with different molar ratios (1:10, 1:2, 2:1, and 10:1), using a homogeneous co-precipitation method. The structural properties were evaluated by different techniques: XRD, UVDR, SEM, N₂ adsorption, and IR. The photocatalytic activity of the samples was tested with the main goal of Eosin Y degradation from wastewaters. The prepared nanocomposites/systems exhibit higher photocatalytic activity than a single semiconductor photocatalyst and ZnO can effectively improve the photocatalytic efficiency of SnO₂ under UV illumination. A direct neural network modeling methodology, based on feed-forward neural networks, was performed in order to evaluate the efficiency of the photodegradation process of Eosin Y, depending of the reaction conditions. The developed model considered the following parameters with significant influence on the approached process: crystallite size, surface area, absorbtion edge, TOC values, time of reaction, and catalyst concentration as inputs and the final dye concentration as output. Accurate results were obtained in the validation phase of the neural model: relative average error under 4 % and a correlation between experimental and simulation data of 0.999.     

Parallel Programming Paradigms and Frameworks in Big Data Era

With Cloud Computing emerging as a promising new approach for ad-hoc parallel data processing, major companies have started to integrate frameworks for parallel data processing in their product portfolio, making it easy for customers to access these services and to deploy their programs. We have entered the Era of Big Data. The explosion and profusion of available data in a wide range of application domains rise up new challenges and opportunities in a plethora of disciplines—ranging from science and engineering to biology and business. One major challenge is how to take advantage of the unprecedented scale of data—typically of heterogeneous nature—in order to acquire further insights and knowledge for improving the quality of the offered services. To exploit this new resource, we need to scale up and scale out both our infrastructures and standard techniques. Our society is already data-rich, but the question remains whether or not we have the conceptual tools to handle it. In this paper we discuss and analyze opportunities and challenges for efficient parallel data processing. Big Data is the next frontier for innovation, competition, and productivity, and many solutions continue to appear, partly supported by the considerable enthusiasm around the MapReduce paradigm for large-scale data analysis. We review various parallel and distributed programming paradigms, analyzing how they fit into the Big Data era, and present modern emerging paradigms and frameworks. To better support practitioners interesting in this domain, we end with an analysis of on-going research challenges towards the truly fourth generation data-intensive science.     

Silicon microneedle array with biodegradable tips for transdermal drug delivery

This paper presents the fabrication process, characterization results and basic functionality of silicon microneedle array with biodegradable tips for transdermal drug delivery. In order to avoid the main problems related to silicon microneedles; the breaking of the top part of the needles inside the skin, a simple solution can be the fabrication of microneedle array with biodegradable tips. A silicon microneedle array was fabricated by deep reactive ion etching (RIE), using the photoresist reflow effect and RIE notching effect. The biodegradable tips were successfully realized using the electrochemical anodization process that selectively generated porous silicon only on the top part of the skin. The porous tips can be degraded within a few weeks if some of them are broken inside the skin during the insertion and release process. The paper presents also the results of in vitro release of calcein with animal skins using a microneedle array with biodegradable tips. Compared to the transdermal drug delivery without microneedle enhancer, the microneedle array had presented significant enhancement of drug release.