Electrical, structural and magnetic properties of polyaniline/pTSA-TiO2 nanocomposites

Polyaniline (PANI)/para-toluene sulfonic acid (pTSA) and PANI/pTSA-TiO2 composites were prepared using chemical method and characterized by infrared spectroscopy (IR), powder X-ray diffraction (XRD), scanning electron microscopy (SEM). The electrical conductivity and magnetic properties were also measured. In corroboration with XRD, the micrographs of SEM indicated the homogeneous dispersion of TiO nanoparticles in bulk PANI/pTSA matrix. Conductivity of the PANI/pTSA-TiO2 was higher than the PAN[/pTSA, and the maximum conductivity obtained was 9.48 (S/cm) at 5 wt% of TiO2. Using SQUID magnetometer, it was found that PANI/pTSA was either paramagnetic or weakly ferromagnetic from 300 K down to 5 K with H-C approximate to 30 Oe and M-r approximate to 0.015 emu/g. On the other hand,PANI/pTSA-TiO2 was diamagnetic from 300 K down to about 50 K and below which it was weakly ferromagnetic. Furthermore, a nearly temperature-independent magnetization was observed in both the cases down to 50 K and below which the magnetization increased rapidly (a Curie like susceptibility was observed). The Pauli susceptibility (chi(pauli)) was calculated to be about 4.8 X 10(-5) and 1.6 x 10(-5)emug(-1) Oe(-1) K for PANI/pTSA and PANI/pTSA-TiO2, respectively.

Optimising indoor phosphine fumigation of paddy rice bag-stacks under sheeting for control of resistant insects

Three indoor, sheeted bag-stack fumigations of paddy rice using aluminium phosphide were undertaken in Guangdong Province, southern China. We measured the effect of two types of sheeting (polyvinylchloride [PVC] or polyethylene [PE]) and two types of floor sealing (clips or fixing into a slot with a rubber pipe) on phosphine concentration and retention. The aim was to test the feasibility of retaining fumigant at a sufficient concentration for long enough to control known resistant insect pests. Each stack was pressure tested and phosphine concentrations measured daily during the fumigation. Cages of test insects in culture medium, including resistant and susceptible strains, were placed inside each stack and could be observed through the clear sheeting. Highest concentrations for the longest period were obtained in a PVC-covered stack that included a ground sheet and wall sheets sealed to the floor with rubber pipes. A similar PVC-covered stack sealed to the floor with clips instead of pipe did not retain gas as efficiently and required re-dosing. A PE-covered stack, with no ground sheet but also with wall sheets sealed to the floor with pipe, produced an acceptable fumigation. Susceptible Rhyzopertha dominica were controlled in 2 days and the most resistant strain in 15 days. Resistant Cryptolestes ferrugineus survived until day 21. The paddy was still free of insect infestation 7 months later when the bag-stack was opened to mill the rice. Pressure half-lives correlated with gas concentration and retention. Sorption appeared to be a major limiting factor, reducing potential fumigant dosage by about 50%. The trials demonstrated the feasibility of sealing bag-stacks to a standard high enough to control all known resistant strains.

Trimming studies on polymer thick-film resistors

PVC-graphite polymer thick-film resistors were trimmed by a conventional air abrasive technique and the post-trim drift in resistance with time was found to be negative. The net decrease in resistance of trimmed resistors in a given time was found to be a function of resistor composition, cutting speed and temperature. Detailed studies showed this decrease to be due to a decrease in cut width with time. Two new methods, namely bombardment trimming and radiation trimming, were also tried for adjusting the resistance of these resistors and the results were compared with those obtained from abrasive trimming studies.

Rhythm Analysis Using Vectorcardiograms

Fourier shape descriptors of vectorcardiograms have been proposed for cardiac rhythm analysis. The technique characterizes the differences in shape and size of the normal and abnormal vectorcardiograms. The specific abnormalities considered are premature ventricular contractions (PVC's) and supraventricular premature contractions (SVPC's).

Physical characterization of plastic surfaces in wearing and cleanability research

Plastic surfaces are a group of materials used for many purposes. The present study was focused on methods for investigation of surface topography, wearing and cleanability of polyvinyl chloride (PVC) model surfaces and industrial plastic surfaces. Contact profilometry, scanning electron microscopy (SEM) and atomic force microscopy (AFM) are powerful methods for studying the topography of plastic surfaces. Although they have their own limitations, they are together an effective tool providing useful information on surface topography, especially when studying laboratory-made PVC model surfaces with known chemical compositions and structures. All examined laboratory-made PVC plastic surfaces examined in this work could be considered as smooth according to both AFM and profilometer measurements because height differences are in the nanoscale on every surface. Industrial plastic surfaces are a complex group of materials because of their chemical and topographical heterogeneity, but they are nevertheless important reference materials when developing cleaning and wearing methods. According to the results of this study the Soiling and Wearing Drum and the Frick-Taber methods are very useful when simulating three-body wearing of plastic surfaces. Both the investigated wearing methods can be used to compare the wearing of different plastic materials using appropriate evaluation methods of wearing and industrial use. In this study, physical methods were developed and adapted from other fields of material research to cleanability studies. The thesis focuses on the methodology for investigating the cleanability of plastic surfaces under realistic conditions, where surface topography and the effect of wear cleanability were among the major topics. A colorimetric method proved to be suitable for examining the cleanability of the industrial plastic surfaces. The results were utilized to evaluate the relationship between cleanability and the surface properties of plastic surfaces. The devices and methods used in the work can be utilized both in material research and product development.

Modifications of surface materials and their effects on cleanability as studied by radiochemical methods

Modifications of surface materials and their effects on cleanability have important impacts in many fields of activity. In this study the primary aim was to develop radiochemical methods suitable for evaluating cleanability in material research for different environments. Another aim was to investigate the effects of surface modifications on cleanabilitity and surface properties of plastics, ceramics, concrete materials and also their coatings in conditions simulating their typical environments. Several new 51Cr and 14C labelled soils were developed for testing situations. The new radiochemical methods developed were suitable for examining different surface materials and different soil types, providing quantitative information about the amount of soil on surfaces. They also take into account soil soaked into surfaces. The supporting methods colorimetric determination and ATP bioluminescence provided semi-quantitative results. The results from the radiochemical and supporting methods partly correlated with each other. From a material research point of view numerous new materials were evaluated. These included both laboratory-made model materials and commercial products. Increasing the amount of plasticizer decreased the cleanability of poly(vinyl chloride) (PVC) materials. Microstructured surfaces of plastics improved the cleanability of PVC from particle soils, whereas for oil soil microstructuring reduced the cleanability. In the case of glazed ceramic materials, coatings affected the cleanability. The roughness of surfaces correlated with cleanability from particle soils and the cleanability from oil soil correlated with the contact angles. Organic particle soil was removed more efficiently from TiO2-coated ceramic surfaces after UV-radiation than without UV treatment, whereas no effect was observed on the cleanability of oil soil. Coatings improved the cleanability of concrete flooring materials intended for use in animal houses.

Sanan vai rakkauden palveluksessa? : Diakonian viralle esitetyt teologiset perusteet Suomen evankelis-luterilaisessa kirkossa vuosina 1997-2006

Tämän tutkielman tehtävänä on selvittää diakonian viralle esitettyjä teologisia perusteita kirkon viralliseen päätöksentekoon liittyvissä asiakirjoissa Suomen evankelis-luterilaisessa kirkossa vuosina 1997-2006. Diakonaatti tarkoittaa kirkon hengelliseen virkaan kuuluvaa papin virasta erillistä palveluvirkaa. Tässä tutkielmassa diakonaattia tarkastellaan kirkkolaissa ilmaistun karitatiivisen diakonian viran näkökulmasta suhteessa kirkon erityiseen virkaan. Systemaattisessa analyysissa on pyritty kuvaamaan aineistosta esiin nouseva diakonian viran keskeinen teologia ja keskeisimmät virkakeskustelussa esiin tulleet ongelmakohdat. Diakonian viran teologisia perusteita ei tässä tutkielmassa pidetä yhtenä kokonaisuutena, vaan siinä tapahtuvat muutokset on pyritty nostamaan esiin historiallisessa viitekehyksessä. Dispositio on tämän vuoksi rakennettu kronologisesti eteneväksi. Suomen evankelis-luterilaisessa kirkossa käytävä keskustelu diakonian viran uudistamisesta on käytännöllisten uudistamistarpeiden lisäksi lähtökohdiltaan yhteydessä kansainväliseen ja ekumeeniseen virkateologiseen kehitykseen, jossa kirkot ovat arvioineet omaa olemustaan ja tehtäväänsä. Virkarakenneuudistuksen pani vireille piispainkokouksen esitys 1/1994 diakonian viran kehittämisestä. Tutkielman keskiössä ovat siihen liittyen komiteamietinnöt Yhdessä kirkon virassa (1997) ja Palvelijoiksi vihityt (2002). Tarkasteltuna ajanjaksona lähdeaineistossa on havaittavissa kirkon viran ja diakonian viran määrittelyä koskeva terminologian ja ordinaatiokäsityksen muutos. Linjausten argumentoinnissa on havaittavissa joitakin epäselvyyksiä, koska esiin otettiin uusia käsitteitä. Kaikki analysoidut asiakirjat katsoivat kirkon viran perustuvan jumalalliseen asetukseen. Sekä kaksisäikeisessä että kolmisäikeisessä virkamallissa diakonian virka ymmärrettiin osaksi Jumalan asettamaa kirkon virkaa. Yksi ministerium ecclesiasticum aukeaa useampaan tehtävään. Kristus asetti kirkolle viran kutsuessaan ja lähettäessään apostolit. Viran muodot ja jakautuminen esimerkiksi piispan, papin ja diakonian virkoihin on nähty periaatteessa inhimillisenä järjestelykysymyksenä, sillä viran jumalallinen asetus ei koske viran muotoja. Asiakirjoissa tukeuduttiin kirkon viran määrittelyssä yhteisen pappeuden perustaan. Kristityt muodostavat uskon ja rakkauden yhteisön, jossa koko seurakunnalla on vastuu tietyistä tehtävistä. Kirkon erityinen palveluvirka rakentuu tälle pohjalle. Aineistosta vahvasti nouseva teema on Lutherin teologiaan perustuva näkemys uskon ja rakkauden sisäkkäisyydestä sekä uskossa läsnäolevasta Kristuksesta rakkauden perustana. Lutherin teologiaan liittyy myös diakonian viran argumentointi sakramentaalisen sanakäsityksen pohjalta. Sanakäsitys on nähty laajasti myös ekumeenisessa dialogissa. Diakonian virkaa tarkasteltiin aineistossa suhteessa seurakuntaan. Yhteisöllisyyden korostus diakonian viran edellytyksenä ja myös sen seurauksena nousi esiin. Yhteisöllisyyden ja siten myös diakonian lähteeksi hahmottui jumalanpalvelus ja ehtoollinen. Ajatus koinoniasta toi mukanaan myös vahvan pneumatologisen perustelun diakonian viralle. Voidaankin sanoa, että diakonian virka tulkittiin lähteissä ankkuroituneeksi Kristukseen. Kristuksen ja kristittyjen yhteyden vuoksi Kristus on sekä diakonian lähde että sen kohde. Aineiston pohjalta on hahmotettavissa diakonian viran teologisena lähtökohtana yhteinen pappeus sekä yhteys sanaan ja sakramentteihin. Viran edellytyksenä on erityinen kutsu, valtuutuksena ordinaatio ja palveluviran sisältönä apostolisen esikuvan mukainen palvelu. Palveluvirka kirkossa perustuu yleiseen pappeuteen siten, että vain yleisen pappeuden omaava kastettu ja uskova kirkon jäsen voi saada erityisen kutsun ja valtuutuksen erityiseen virkaan. Yleinen pappeus ei kuitenkaan yksin riitä virkaan eikä sitä ole mahdollista johtaa yleisestä pappeudesta. Erityinen kirkon virka edellyttää lisäksi erityisen Jumalan kutsun, jonka kirkko hyväksyy ja vahvistaa. Jumalan kutsun julkinen vahvistaminen ja tunnustaminen tapahtuu ordinaatiossa. Diakonian virkaa koskevassa suomalaisessa keskustelussa on oltu yksimielisiä siitä, että diakonian virkaan sisältyvät karitatiivinen, katekeettinen ja liturginen funktio. Käytännössä diakonian viralla on kuitenkin vahvasti karitatiivinen luonne Suomen evankelis-luterilaisessa kirkossa.

In situ synthesis and characterization of polyaniline-CaCu3Ti4O12 nanocrystal composites

High dielectric constant (ca. 2.4 x 10(6) at 1 kHz) nanocomposite of polyaniline (PANI)/CaCu3Ti4O12 (CCTO) was synthesized using a simple procedure involving in situ polymerization of aniline in dil. HCl. The PANI and the composite were subjected to X-ray diffraction, Fourier transform infrared, thermo gravimetric, scanning electron microscopy and transmission electron microscopy analyses. The presence of the nanocrystallites of CCTO embedded in the nanofibers of PANI matrix was established by TEM. Frequency dependent characteristics of the dielectric constant. dielectric loss and AC conductivity were studied for the PANI and the composites. The dielectric constant increased as the CCTO content increased in PANI but decreased with increasing frequency (100 Hz-1 MHz) of measurement. The dielectric loss was two times less than the value obtained for pure PANI around 100 Hz. The AC conductivity increased slightly up to 2 kHz as the CCTO content increased in the PANI which was attributed to the polarization of the charge carriers.

Charge transport properties of water dispersible multiwall carbon nanotube-polyaniline composites

The transmission electron microscopy images of in situ prepared multiwall carbon nanotubes (MWNTs)and polyaniline (PANI) composites show that nanotubes are well dispersed in aqueous medium, and the nanofibers of PANI facilitate intertube transport. Although low temperature transport indicates variable range hopping (VRH) mechanism, the dc and ac conductivity become temperature independent as the MWNT content increases. The onset frequency for the increase in conductivity is observed to be strongly dependent on the MWNT weight percent, and the ac conductivity can be scaled onto a master curve. The negative magnetoresistance is attributed to the forward interference scattering mechanism in VRH transport. (C) 2010 American.

Peroxomonosulphate initiated graft copolymerization of aniline onto poly(propylene) fibre - A kinetic approach

Graft copolymerization of poly(aniline) (PANI) onto poly(propylene) (PP) fibre was carried out in aqueous acidic medium under nitrogen atmosphere by using peroxomonosulphate (PMS) as a lone initiator. The non-conducting fibre was now made into a conducting one through the chemical grafting of PANI units onto the PP fibre backbone. The content of PANI in the backbone was found to vary while varying the [ANI], [PMS] and amount of PP fibre. Various graft parameters were evaluated. The chemical grafting of PANI onto PP fibre was confirmed by conductivity measurements.

Novel polymeric flame retardant plasticizers for poly(vinyl chloride)

Polyphosphate esters have been used as polymeric flame retardant plasticizers in poly(vinyl chloride); thermal and flammability studies were carried out to evaluate their efficiencies as fire retardants. A comparison is also made on the fire retardancy of the conventional simple phosphates with that of the polyphosphates as novel fire retardant plasticizers for PVC.

Preparation, Structural, and Electrical Studies of Polyaniline/ZnFe2O4 Nanocomposites

Polyaniline/ZnFe2O4 nanocomposites were synthesized by a simple and inexpensive one-step in situ polymerization method in the presence of ZnFe2O4 nanoparticles. The structural, morphological, and electrical properties of the samples were characterized by wide angle X-ray diffraction (WAXD), Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), and thermogravimetric analysis (TGA). WAXD and SEM revealed the formation of polyaniline/ZnFe2O4 nanocomposites. Infrared spectroscopy indicated that there was some interaction between the ZnFe2O4 nanoparticles and polyaniline. The dc electrical conductivity measurements were carried in the temperature range of 80 to 300 K. With increase in the doping concentration of ZnFe2O4, the conductivity of the nanocomposites found to be decreasing from 5.15 to 0.92 Scm(-1) and the temperature dependent resistivity follows ln rho(T) similar to T-1/2 behavior. The nanocomposites (80 wt % of ZnFe2O4) show a more negative magnetoresistance compared with that of pure polyaniline (PANI). These results suggest that the interaction between the polymer matrix PANI and zinc nanoparticles take place in these nanocomposites. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci 120: 2856-2862, 2011

Thermal expansion of irradiated polyvinyl chloride from 10 K to 340 K

The coefficient of thermal expansion is measured for irradiated Polyvinyl Chloride (PVC) from 10K to 340K. The samples of PVC are irradiated, up to 500 Mrad in steps of 100 Mrad, in air at room temperature by using Co gamma rays with a dose rate of 0.3 Mrad/h. The PVC is an amorphous sample which is confirmed by X-ray diffraction. The coefficient of thermal expansion is found to decrease with radiation dose from 10K to 110K and it increaseswith radiation dose from 110K to 340K. The results are explained on the basis of radiation induced degradation of the sample.

Polyaniline modified electrodes for detection of dyes

Polyaniline (PANI) is one of the most extensively used conjugated polymers in the design of electrochemical sensors. In this study, we report electrochemical dye detection based on PANI for the adsorption of both anionic and cationic dyes from solution. The inherent property of PANI to adsorb dyes has been explored for the development of electrochemical detection of dye in solution. The PANI film was grown on electrode via electrochemical polymerization. The as grown PANI film could easily adsorb the dye in the electrolyte solution and form an insulating layer on the PANI coated electrode. As a result, the current intensity of the PANI film was significantly altered. Furthermore, PANI coated stainless steel (SS) electrodes show a change in the current intensity of Fe2+/Fe3+ redox peaks due to the addition of dye in electrolyte solution. PANI films coated on both Pt electrodes and non-expensive SS electrodes showed the concentration of dye adsorbed is directly proportional to the current intensity or potential shift and thus can be used for the quantitative detection of textile dyes at very low concentrations. (C) 2011 Elsevier B.V. All rights reserved.

Electrocatalytic efficiency of polyaniline by cyclic voltammetry and electrochemical impedance spectroscopy studies

Electrochemical redox reactions of ferrous/ferric (Fe2+/Fe3+) and hydroquinone/quinone (H(2)Q/Q) were studied on Pt and polyaniline (PANI)-deposited Pt electrodes in 0.5 M H2SO4-supporting electrolyte by cyclic voltammetry and ac impedance spectroscopy. A comparison of the experimental data obtained with the Pt and PANI/Pt electrodes suggested that the reactions were catalyzed by the PANI. Based on a relative increase in peak currents of cyclic voltammograms, catalytic efficiency (gamma(cv)) of the PANI was defined. There was an increase in gamma(cv) with an increase of scan rate and a decrease of concentration of Fe2+/Fe3+ or H(2)Q. The complex plane impedance spectrum of the electrode consisted of a semicircle in high frequency range and a linear spike in low frequency range. The exchange current density (i(0)) calculated using the semicircle part of the impedance showed Butler-Volmer kinetics with respect to concentration dependence. From a relative increase of i(0) on the PANI/Pt electrode, catalytic efficiency (gamma(eis)) was evaluated. (C) 2002 Elsevier Science B.V. All rights reserved.