Composites of novel biodegradable copolyamides based on adipic acid, 1,6-hexane diamine,and L-glycine with short E-glass fibers. II. Preparation and properties

A study was conducted on the preparation of composite materials based on novel biodegradable copolyamides reinforced with E glass fibers by using the hand lay-up technique. Differential thermal analysis (DTA) and wide angle x-ray diffraction patterns were employed for investigating the effect of transcrystallinity on percentage crystallinity of composites. The thermal properties of composites (T_g and T_m) were determined with DTA and dynamic mechanical thermal analyzer (DMTA) measurements. Void fractions were evaluated from density measurements and correlated to glass fiber contents. The stress–strain curves and compression strength measurements were recorded and correlated with the glass fiber content, void content, and the percentage amino acid content of the copolymers. Although high α-amino acid contents caused a decrease in T_g and T_m and the tensile strength of copolyamides, the introduction of glass fibers was found to counterbalance this effect by initiating an increase in the percentage crystallinity. © 1995 John Wiley & Sons, Inc.     

Sulfide removal in wastewater from petrochemical industries by autotrophic denitrification

An alternative flowchart for the biological removal of hydrogen sulfide from oil-refining wastewater is presented; autotrophic denitrification in a multi-stage treatment plant was utilized. A pilot-scale plant was fed with a mixture of the following constituents: (a) original wastewater from an oil refining industry (b), the effluent of the existing nitrification-stage treatment plant and (c) sulfide in the form of Na2S. Anoxic sulfide to sulfate oxidation, with nitrate as a terminal electron acceptor, proved very successful, as incoming concentrations of 110 mg S2-/L were totally converted to SO(4)2-. At complete denitrification, the concentration of S2- in the reactor effluent was less than 0.1mg/L. Fluctuating S2- concentration in the feed could be tolerated without any problems, as the accumulated sulfide in the effluent of the denitrification stage is oxidized aerobically in a subsequent activated-sludge treatment stage. This alternative new treatment scheme was further introduced at the refinery's wastewater processing plant. Thus, complete H2S removal is now accomplished by the combination of the proposed biological method and the existing stripping with CO2. As a result, stripping, and thus its cost, is reduced by 70%.     

Selenium content in selected foods from the Greek market and estimation of the daily intake

The total selenium content of foods purchased from the North West part of Greece was determined using hydride generation atomic fluorescence spectroscopy. The results of this study were within the range from other countries. The overall mean average of selenium concentration of the foods examined, in decreasing order, was found in sesame seeds (783.1 ng g(-1)), fish (246 ng g(-1)), legumes (162.5 ng g(-1)), eggs (123 ng g(-1)), bread (91.9 ng g(-1)), meat (71.7 ng g(-1)), cheese (69.8 ng g(-1)), yoghurt (23.6 ng g(-1)), nuts (19.6 ng g(-1)), milk (15.4 ng g(-1)), vegetables (6.5 ng g(-1)) and fruits (3.4 ng g(-1)). Considering the average daily individual consumption of these foods by Greeks, the average daily dietary intake of selenium supplied by this source is 39.3 microg per capita.     

Toll-Like Receptors in the Pathogenesis of Essential Hypertension. A Forthcoming Immune-Driven Theory in Full Effect

Essential hypertension (EH) is a highly heterogenous disease with a complex etiology. Recent evidence highlights the significant contribution of subclinical inflammation, triggered and sustained by excessive innate immune system activation in the pathogenesis of the disease. Toll-like receptors (TLRs) have been implied as novel effectors in this inflammatory environment since they can significantly stimulate the production of pro-inflammatory cytokines, the migration and proliferation of smooth muscle cells and the generation of reactive oxygen species (ROS), facilitating a low-intensity inflammatory background that is evident from the very early stages of hypertension. Furthermore, the net result of their activation is oxidative stress, endothelial dysfunction, vascular remodeling, and finally, vascular target organ damage, which forms the pathogenetic basis of EH. Importantly, evidence of augmented TLR expression and activation in hypertension has been documented not only in immune but also in several non-immune cells located in the central nervous system, the kidneys, and the vasculature which form the pathogenetic core systems operating in hypertensive disease. In this review, we will try to highlight the contribution of innate immunity in the pathogenesis of hypertension by clarifying the deleterious role of TLR signaling in promoting inflammation and facilitating hypertensive vascular damage.     

Critical power two wheeler driving patterns at the emergence of an incident

The paper proposes a methodology based on Bayesian Networks for identifying the power two wheeler (PTW) driving patterns that arise at the emergence of a critical incident based on high resolution driving data (100 Hz) from a naturalistic PTW driving experiment. The proposed methodology aims at identifying the prevailing PTW drivers’ actions at the beginning and during critical incidents and associating the critical incidents to specific PTW driving patterns. Results using data from one PTW driver reveal three prevailing driving actions for describing the onset of an incident and an equal number of actions that a PTW driver executes during the course of an incident to avoid a crash. Furthermore, the proposed methodology efficiently relates the observed sets of actions with different types of incidents occurring during overtaking or due to the interactions of the rider with moving or stationary obstacles and the opposing traffic. The observed interrelations define several driving patterns that are characterized by different initial actions, as well as by different likelihood of sequential actions during the incident. The proposed modeling may have significant implications to the efficient and less time consuming analysis of the naturalist data, as well as to the development of custom made PTW driver assistance systems.     

Relationship archetypes in aftermarkets#

Aftermarket sales and profits have become an increasingly important part of an Original Equipment Manufacturer’s (OEM) business model. The attractiveness of the after-sales business, however, has also been recognised by other parties (e.g. competitors, suppliers) who try to capture a share of the aftermarket. A highly profitable aftermarket creates a strong incentive for the supplier to disintermediate the established supply chain and sell directly to the OEM’s aftermarket customers. To counter this threat, OEMs must be aware of the activities and actors on their aftermarket, and should understand and systematically analyse the existing or changing business relationships among the incumbent and emergent actors in the aftermarket ecosystem. In this exploratory study we use case study research with 29 companies (customer, OEM, supplier, or competitor) and draw on social network theory – in particular the concepts of structural embeddedness, structural hole and supply chain disintermediation – to examine and discuss triadic and tetradic relationship constellations (archetypes) in aftermarkets. Recognising these relationship archetypes in aftermarkets can help firms to adapt their after-sales strategies and protect the competitive advantage, revenues and profits stemming from their after-sales business.     

Ion Electron–Coupled Functionality in Materials and Devices Based on Conjugated Polymers

The coupling between charge accumulation in a conjugated polymer and the ionic charge compensation, provided from an electrolyte, defines the mode of operation in a vast array of different organic electrochemical devices. The most explored mixed organic ion–electron conductor, serving as the active electrode in these devices, is poly(3,4‐ethyelenedioxythiophene) doped with polystyrelensulfonate (PEDOT:PSS). In this progress report, scientists of the Laboratory of Organic Electronics at Linköping University review some of the achievements derived over the last two decades in the field of organic electrochemical devices, in particular including PEDOT:PSS as the active material. The recently established understanding of the volumetric capacitance and the mixed ion–electron charge transport properties of PEDOT are described along with examples of various devices and phenomena utilizing this ion–electron coupling, such as the organic electrochemical transistor, ionic–electronic thermodiffusion, electrochromic devices, surface switches, and more. One of the pioneers in this exciting research field is Prof. Olle Inganäs and the authors of this progress report wish to celebrate and acknowledge all the fantastic achievements and inspiration accomplished by Prof. Inganäs all since 1981.     

Simultaneous detection of pH changes and histamine release from oxyntic glands in isolated stomach

Real-time simultaneous detection of changes in pH and levels of histamine over the oxyntic glands of guinea pig stomach have been investigated. An iridium oxide pH microelectrode was used in a potentiometric mode to record the pH decrease associated with acid secretion when the sensor approached the isolated tissue. A boron-doped diamond (BDD) microelectrode was used in an amperometric mode to detect histamine when the electrode was placed over the tissue. Both sensors provided stable and reproducible responses that were qualitatively consistent with the signaling mechanism for acid secretion at the stomach. Simultaneous measurements in the presence of pharmacological treatments produced significant variations in the signals obtained by both sensors. As the H2 receptor antagonist cimetidine was perfused to the tissue, histamine levels increased that produced an increase in the signal of the BDD electrode whereas the pH sensor recorded a decrease in acid secretion as expected. Addition of acetylcholine (ACh) stimulated additional acid secretion detected with the pH microelectrode whereas the BDD sensor recorded the histamine levels decreasing significantly. This result shows that the primary influence of ACh is directly on the parietal cell receptors rather then the ECL cell receptors of the oxyntic glands. These results highlight the power of this simultaneous detection technique in the monitoring and diagnosis of physiological significant signaling mechanisms and pathways.     

Development of a silk and collagen fiber scaffold for anterior cruciate ligament reconstruction

The objective of this study was to determine a silk-collagen fiber ratio for an anterior cruciate ligament (ACL) reconstruction composite scaffold device. Composite fiber scaffolds with silk volumes ≥14 % and collagen volume <86 % demonstrated comparable or greater initial ultimate tensile stress relative to the human ACL. Silk scaffolds implanted subcutaneously and intraarticularly in rabbits demonstrated an 84 and 92 % reduction in strength with a 26 and 22 % reduction in volume after 8 weeks, respectively. The mechanical degradation findings of this preliminary study suggest that a composite scaffold with an initial UTS value of at least 129 MPa, or roughly a 48:52 silk to collagen volume ratio meets the minimal mechanical requirements necessary to proceed to a functional ACL reconstruction study in vivo.