Although free-standing sheets of multiwalled carbon nanotubes (MWCNT) can provide interesting electrochemical and physical properties as electrodes for redox flow batteries, the full potential of this class of materials has not been accessible as of yet. The conventional fabrication methods produce sheets with micro-porous and meso-porous structures, which significantly resist mass transport of the electrolyte during high-current flow-cell operation. Herein, we developed a method to fabricate high performance macro-porous carbon nano-foam free standing sheets (Puffy Fibers, PF), by implementing a freeze-drying step into our low cost and scalable surface-engineered tape-casting (SETC) fabrication method, and we show the improvement in the performance attained as compared with a MWCNT sheet lacking any macro pores (Tape-cast, TC). We attribute the higher performance attained by our in-lab fabricated PF papers to the presence of macro pores which provided channels that acted as pathways for electrolytic transport within the bulk of the electrode. Moreover, we propose an electrolytic transport mechanism to relate ion diffusivity to different pore sizes to explain the different modes of charge transfer in the negative and the positive electrolytes. Overall, the PF papers had a high wettability, high porosity, and a large surface area, resulting in improved electrochemical and flow-cell performances.

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In this work, chemical oxidation was used to polymerize conjugated polymer "Polypyrrole" at room temperature Graphene nanoparticles were added by in situ-polymerization to get (PPY-GN) nano. Optical and Electrical properties were studied for the nanocomposites. optical properties of the nanocomposites were studied by UV-Vis spectroscopy at wavelength range (200 -800 nm). The result showed optical absorption spectra were normally determined and the result showed that the maximum absorbance wave length at 280nm and 590nm. The optical energy gap has been evaluated by direct transition and the value has decreased from (2.1 eV for pure PPy) to (1.3 eV for 5 %wt. of GN). The optical constants such as the band tail width ΔE was evaluated, the value of ΔE for pure PPy was (0.0949eV) while for 5 wt. % of GN it was (0.5156 eV), It has been observed that the Urbach tail for pure PPy was smaller than that for PPy/GN nanocomposites and it increase as GN concentration increases. The A.C electrical conductivity at range of frequency (103Hz-106Hz) was increased by increasing the frequency and GN concentration about four order of magnitude. The s value was about (0.653-0.962) which means that the mechanism of conductivity is correlated hopping mechanism (C. H. P.). The dielectric constant and dielectric lose were determined and found to decrease with increasing frequency.

Abstract  In this work, pure Polypyrrole (PPy) and Polypyrrole (PPy)/Graphene (GN) was synthesized by in-situ polymerization in different weight percentages (0.1, 0.3, 0.5, 1, 3 and 5 wt.% (g)) of GN nano particles using chemical oxidation method at room temperature. The FTIR, SEM and electrical properties were studies for the nano composites. The result show that when concentration of GN Nano particle increase, the electrical conductivity increased and the graphene sheets were merging to form a continuous area of the GN through the polypyrrole base material. The FTIR spectra shows that the characteristics absorption peaks of polypyrrole that is, 1546.80, 1463.87 and 3400.27 cm-1(stretching vibration in the pyrrole ring), and at 1080.06 cm-1 was assigned to C—O stretching and at 1589.23 cm-1 was assigned to C—C vibration of carbon ring in graphene. الخلاصة حضر البولي بايرول النقي و المطعم بدرجة حرارة الغرفه بطريقة الاكسدة الكيميائية و قد تم استخدام جسيمات الكرافين النانوية و بالنسب التالية (0.1, 0.3, 0.5, 1. 3, ,5 %). و تم استخدام طيف الاشعه تحت الحمراء و ماسح الالكترون المجهري لتشخيص البولي بايرول المحضر كما قيست التوصيلية الكهربائية المستمرة و اوجدت النتائج ان التوصيلية تزداد بزيادة درجه الحرارة و كذالك بزيادة الكرافين .

Tobacco smoking is affecting fundamental aspects of human health. This preliminary study was set to investigate the effect of tobacco smoking on the salivary pH. The saliva is an essential part of healthy oral cavity, it is mostly made of water and also contains other substances that your body needs to digest food and keep your teeth strong. Smoking is expected to have an effect on salivary pH. The salivary pH levels were measured using digital pH meter in 100 voluntary participants in Baghdad- Iraq. The participants were divided into two groups of 50 subjects in each group: smokers and non-smokers. Along with that, the reasons behind tobacco smoking also were investigated in a separate group of 82 smokers using a prepared questioner for this purpose. The results showed decrease salivary pH average levels in the tobacco smokers compare to the non-smoker group (7.058 and 7.168 respectively), however, these differences did not reach the significant level. Regarding the investigation of the reasons behind tobacco smoking habit, seeking for fun, overcome psychiatric problem, anger, friendship, relieves stress and anxiety and work problems (((29 (35.4%), (28(34.1%), 27(32.9%), 22(26.8%), 22(26.8%), 21(25.6%) respectively, were on the top of the listed reasons for smoking tobacco cigarettes stated by the questioned participants. Participants who think that cigarettes could help to relieve boredom (age average 35.3 yrs (17-55 yrs) smoke the largest number of cigarettes (30(20-60) compare to those who smoke for other reasons.