Characterization of the polymer of a dipyrrolyl monomer by pyrolysis mass spectrometry

In this work, characterization of a homopolymer of succinic acid bis(4-pyrrol-1-ylphenyl) ester prepared by galvonastatic polymerization was carried out by direct pyrolysis mass spectrometry. Although decomposition of the monomer yielding mainly butadionic acid and pyrrole occurred under the galvonastatic polymerization conditions, growth of the polymer through the pyrrole moieties was also achieved, yielding a ladder-type polymer film. The polypyrrole chains contained both quinoid and aromatic units as in the case of polypyrrole, yet the extent of network structure was significantly diminished. A three-step mechanism is proposed. for the thermal decomposition process. The first step involves the cleavage Of C4H4NC6H4O end groups. In the second step, decomposition of phenyl ester units and polypyrrole chains having quinoid structure takes place. The final stage of thermal degradation was attributed to decomposition of polypyrrole chains having aromatic structure. (C) 2004 Society of Chemical Industry

Characterization of conducting copolymers of succinic acid bis-(-4-pyrrol-1-yl-phenyl) ester and thiophene via pyrolysis mass spectrometry

In this work, a direct pyrolysis mass spectrometry technique was applied to characterize a conducting copolymer of succinic acid bis-(4-pyrrol-1-yl-phenyl) ester (SM) and thiophene prepared by electrochemical polymerization. Thermal degradation behavior of both components was quite similar to those of the corresponding homopolymers, PSM, and polythiophene PTh. Yet, detection of oligomers and mixed dimers of both monomers in the high temperature pyrolysis mass spectra confirmed the formation of a copolymer. Furthermore, evolution of SM monomer in the temperature range where the fragments, due to the thermal degradation of PTh chains, have been detected. Also, the generation of dimer of thiophene in the temperature range, where the fragments associated with PSM have been observed, pointed out the presence of thiophene and SM units along the PTh and PSM chains. However, as thermal stabilities of PTh and PSM chains were nearly identical to the corresponding homopolymers, it may be concluded that the presence of other monomer or low molecular weight oligomers along the chains of each component did not significantly affect the thermal characteristics

Optimizing Sensitivity in a Fluid-Structure Interaction-Based Microfluidic Viscometer: A Multiphysics Simulation Study

Fluid-structure interactions (FSI) are used in a variety of sensors based on micro- and nanotechnology to detect and measure changes in pressure, flow, and viscosity of fluids. These sensors typically consist of a flexible structure that deforms in response to the fluid flow and generates an electrical, optical, or mechanical signal that can be measured. FSI-based sensors have recently been utilized in applications such as biomedical devices, environmental monitoring, and aerospace engineering, where the accurate measurement of fluid properties is critical to ensure performance and safety. In this work, multiphysics models are employed to identify and study parameters that affect the performance of an FSI-based microfluidic viscometer that measures the viscosity of Newtonian and non-Newtonian fluids using the deflection of flexible micropillars. Specifically, we studied the impact of geometric parameters such as pillar diameter and height, aspect ratio of the pillars, pillar spacing, and the distance between the pillars and the channel walls. Our study provides design guidelines to adjust the sensitivity of the viscometer toward specific applications. Overall, this highly sensitive microfluidic sensor can be integrated into complex systems and provide real-time monitoring of fluid viscosity

Evaluation of the Water Quality of the Ilke Stream According to Biotic Indices Based on Benthic Macroinvertebrates (West Anatolia, Turkey)

Benthic macroinvertebrates can provide an integrated picture of environmental changes. Health of freshwaters can be assessed based on measured changes in the ecological structure of benthic macroinvertebrates. During the study period, 33 taxa were determined in Ilke Stream. As a result of principle component analysis (PCA), mainly nine components (T degrees C, EC, TDS, BOD5, NH4-N, NO2-N, NO3-N, PO4-P and CI-) account for 92% of the total variance among the water quality parameters. As a result of the UPGMA analysis, the highest similarity value was observed between the 1th and 2nd sampling points. SI, BMWP, ASPT and BBI indices were more proper than FBI index to determine the water quality of Ilke Stream. The results indicate that these indices should be adapted based on the ecological, geomorphological and environmental features of the regions

Crossover of spectral reflectance lineshapes in Ge-doped VO2 thin films

Adjusting the insulator-to-metal transition (IMT) temperature of vanadium dioxide (VO2) thin films for use in optical applications can be achieved via doping with various elements. An important aspect, which was largely overlooked in the literature, is the change in the spectral reflectivity lineshapes upon dopant addition in order to control the critical temperature TC of VO2. Here, we demonstrate that the TC in VO2 can be varied effectively with Ge doping. Moreover, we observe that the spectral lineshapes of the Ge doped VO2 films reveal rather interesting characteristics, such as a distinct crossover in the high-reflection and low-reflection regions during the IMT that could allow frequency specific spectral functionalities

Pauci-immune crescentic glomerulonephritis caused to dilemma in a patient with suspected systemic lupus erythematosus: a case report

Systemic lupus erythematosus (SLE) is a chronic autoimmune disease and there is a distinct differentiation of clinical manifestations. Lupus nephritis (LN) is clinically apparent in approximately half of patients. A kidney biopsy is essential to define the kidney injury, exclude other injurious causes, and determine the histopathologic subtypes. Autoantibodies are crucial to the pathogenesis and the deposition of immune complexes in glomeruli is a hallmark of LN. The histopathology of LN is quite varied. Despite pauci-immune LN being an unexpected condition in SLE, it has been observed rarely with the presence of antineutrophil cytoplasmic autoantibodies (ANCA). We present a young male who was admitted to the emergency with syncope. The brain imaging revealed small infarct areas and signs of cerebral vasculitis. Also, he had elevated inflammatory markers, moderate proteinuria, and preserved kidney function. Anti-nuclear antibodies and anti-dsDNA were positive. Pauci-immune crescentic glomerulonephritis (PICGN) was observed in a kidney biopsy, however, ANCA was negative. SLE diagnosis was established by neurological manifestation, specific antibodies, proteinuria, and kidney biopsy findings. We administered a combination induction regimen, including pulse steroid and parenteral cyclophosphamide. The proteinuria was resolved in the follow-up. Our case highlights that SLE-associated ANCA-negative PICGN can be the initial presentation in the absence of typical manifestations. LN exhibits various pathological mechanisms in the kidney. As a consequence, SLE should be considered in the differential diagnosis of all forms of kidney injury

Morphology induced spectral reflectance lineshapes in VO2 thin films

In this work, we study the spectral reflectance of VO2 thin films and identify the specific contributions of the morphology and phase transition to optical spectra. The formation of highly [011] textured VO2 thin films on Si was achieved by an oxidation process starting with a metallic V thin film grown on an [001] Si substrate by an evaporation technique. Structural (XRD and Raman) and spectroscopic (XPS) characterization results indicate high purity VO2 formation with different sizes at various annealing temperatures without any change in the composition. Temperature dependent spectral reflectance distributions reveal that the insulator-to-metal transition (IMT) phase transition temperature of the VO2 nanostructures shows a slight size-dependence (approximate to 3 degrees C), but this feature can be overshadowed by morphology that can lead to the misinterpretation of transition characteristics. The spectral line shape of the reflectance curves in the visible and near-infrared regions show substantially different characteristics for the samples annealed at different temperatures. Using numerical scattering calculations, we conclude that the changes in the optical response can be explained by morphological effects instead of changes in the intrinsic material properties such as a shift in the IMT temperature. Furthermore, the main mechanism leading to different spectral line shapes is the morphological differences leading to diffuse and specular reflectance

Polyethyleneimine brushes effectively inhibit encrustation on polyurethane ureteral stents both in dynamic bioreactor and in vivo

ERTAS, NUSRET/0000-0002-9770-3292WOS: 000390967200135PubMed: 27987673Polyurethane (PU) ureteral stents have been widely used as biomedical devices to aid the flow of the urine. Due to the biofilm formation and encrustation complications it has been hindered their long term clinical usage. To overcome these complications, in this study, cationic polyethyleneimine (PEI) brushes grafted on PU stents and their performances were tested both in a dynamic biofilm reactor system (in vitro) and in a rat model (in vivo). Thus, we hypothesized that PEI brushes inhibit bacterial adhesion owing to the dynamic motion of brushes in liquid environment. In addition, cationic structure of PEI disrupts the membrane and so kills the bacteria on time of contact. Cationic PEI brushes decreased the biofilm formation up to 2 orders of magnitude and approximately 50% of encrustation amount in respect to unmodified PU, in vitro. In addition, according to Atomic Absorption Spectroscopy (AAS) results, approximately 90% of encrustation was inhibited on in vivo animal models. Decrease in encrustation was clearly observed on the stents obtained from rat model, by Scanning Electron Microscopy (SEM). Also, histological evaluations showed that; PEI brush grafting decreased host tissue inflammation in close relation to decrease in biofilm formation and encrustation. As a results; dual effect of anti adhesive and contact-killing antibacterial strategy showed high efficiency on PEI brushes grafted PU stents both in vitro and in vivo. (C) 2016 Elsevier B.V. All rights reserved.Scientific and Technological Research Council Turkey of (TUBITAK) [112M293]This study is financially supported by The Scientific and Technological Research Council Turkey of (TUBITAK) (Grant no: 112M293)

Supercapacitors Based on Polymeric Dioxypyrroles and Single Walled Carbon Nanotubes

This paper reports a novel supercapacitor electrode design based on poly­(3,4-propylenedioxypyrrole) (PProDOP) electropolymerized onto thin films of single walled carbon nanotubes (SWNTs) on glass substrates. This permits the electropolymerization of thicker PProDOP films than can be deposited onto flat gold-coated Kapton electrodes and a correspondingly greater capacitance per unit area. A pyrene functionalized polyfluorene, designated Sticky-PF, was designed and used as an effective monolayer interfacial adhesion modifier between the SWNT films and PProDOP via noncovalent self-assembly onto the SWNT film surfaces before polymer electrodeposition. The thickness of the electrodeposited PProDOP was found to be self-limiting at thicknesses characteristic of each substrate electrode. Optimized areal capacitance values for PProDOP on flat gold and Sticky-PF coated SWNT films were measured to be 8.1 mF/cm² and 16.4 mF/cm², respectively, with the twofold enhancement due to the thicker films possible on the SWNT electrode. The specific capacitance of PProDOP on gold and Sticky-PF|SWNT film substrates were found to be similar at 141 F/g and 122 F/g, respectively, indicating the capacitance to be due to the electroactive polymer. The areal capacitance values of the corresponding supercapacitor devices constructed with Au/Kapton substrates was 3.2 mF/cm², whereas a significantly greater value of 8.8 mF/cm² was measured for the Sticky-PF|SWNT film substrates. The supercapacitors prepared using the Au/Kapton substrates were highly stable, retaining 80% of their electroactivity after 32 700 nonstop charge/discharge cycles (100% depth of discharge). Supercapacitors made using the Sticky-PF|SWNT substrates showed a steady loss of capacitance to about 57% of the original value (to 5.0 mF/cm²) after 32 700 charge/discharge cycles, which was still 38% larger than the initial capacitance of the gold electrode devices