Ferhat Bozduman

Efficacy of endodontic applications of ozone and low‐temperature atmospheric pressure plasma on root canals infected with Enterococcus faecalis

This study aimed to compare the antimicrobial efficacy of low‐temperature atmospheric pressure plasma (LTAPP) design and gaseous ozone delivery system with 2·5% NaOCl on Enterococcus faecalis in root canal walls and dentine tubules. The samples were divided into LTAPP (n = 12), ozone (n = 12), NaOCl (positive control, n = 12) and saline (negative control, n = 6) groups. Microbial samples were collected using paper points and dentin chips from root canals. Antimicrobial efficacy was assessed by counting the colony‐forming units of Ent. faecalis before and after each irrigation protocol. Data were analysed using Kruskal–Wallis, Wilcoxon signed‐rank, Friedman and Bonferroni t (Dunns test)‐tests (P = 0·05). The microbial sampling with paper points showed antibacterial efficacy of NaOCl, LTAPP, ozone and saline in descending order, respectively (P < 0·05). The microbial sampling with dentin chips demonstrated a superior efficacy of LTAPP compared with NaOCl in the middle third (P < 0·05), while both had similar effects in coronal and apical thirds (P > 0·05). NaOCl and LTAPP were better than ozone at the coronal and middle parts of the root canals (P < 0·05). These findings led us to suggest that LTAPP, which has no thermal and chemical effects, may be of great aid in endodontic treatment.

Complementary all Solid State Electrochromic Devices Using Carboxymethyl Cellulose Based Electrolytes

The paper presents the results of the research on a new polymer-membrane and gel electrolytes for electrochromic devices. A complementary solid-state electrochromic device consisting of cathodically coloring working electrode of WO3 and anodically coloring counter electrode of NiO films is prepared to compare the effects of gel or membrane forms of carboxymethyl cellulose (CMC) polymer electrolyte on the electrochromic properties of devices. The performance evaluations of the complementary solid-state electrochromic devices indicate good reversibility, low power consumption of ±3 V in colored state, high variation of transmittance changing of 64% in gel electrolyte, and lower 7% in membrane electrolyte and good memory effect under open-circuit conditions. CMC based electrolytes can be used as an ion-conducting medium and be a good candidate for complementary electrochromic devices owing to, the improved properties as well as its cheapness.

Biosensing applications of titanium dioxide coated graphene modified disposable electrodes.

In the present work, preparation of titanium dioxide coated graphene (TiO2/graphene) and the use of this nanocomposite modified electrode for electrochemical biosensing applications were detailed. The nanocomposite was prepared with radio frequency (rf) rotating plasma method which serves homogeneous distribution of TiO2 onto graphene. TiO2/graphene was characterized with scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD) analysis. Then, this nanocomposite was dissolved in phosphate buffer solution (pH 7.4) and modified onto disposable pencil graphite electrode (PGE) by dip coating for the investigation of the biosensing properties of the prepared electrode. TiO2/graphene modified PGE was characterized with SEM, EDS and cyclic voltammetry (CV). The sensor properties of the obtained surface were examined for DNA and DNA-drug interaction. The detection limit was calculated as 1.25mgL(-1) (n=3) for double-stranded DNA (dsDNA). RSD% was calculated as 2.4% for three successive determinations at 5mgL(-1) dsDNA concentration. Enhanced results were obtained compared to the ones obtained with graphene and unmodified (bare) electrodes.

Atmospheric Pressure 2.45-GHz Microwave Helium Plasma

A waveguide-based microwave plasma system was built using a resonant cavity and a quartz tube. 2.45 GHz 850 W magnetron was used to obtain helium discharge without an igniter. The temporal images of discharge were recorded on microsecond time scales using an intensified charge-coupled device camera. The excitation temperature was calculated as 3385 K using the helium lines, which were obtained from emission spectrum of the discharge. The gas temperature was measured as 1208 K by a thermocouple.

A Comparison Study of Microwave and Radio Frequency Plasma Polymerized PEDOT Thin Films

PEDOT films were deposited by microwave (MW) and radio frequency (RF) plasma in a medium pressure of 0.02 Torr without precursor. In-situ optical emission spectroscopy (OES) measurement was carried out to determine plasma phase and to adjust discharge parameters. The other spectroscopic methods were used to characterize deposited thin films and to compare the effect of discharge parameters on the process. Conductivity values were found to be around up to 10−5 S/cm for MW plasma, and 10−8 S/cm for RF plasma deposited PEDOT films, without the addition of a doping agent. It was found that both plasma polymerization methods resulted in crosslinked PEDOT structures.

Platinum-free counter electrodes of plasma-modified hybrid nanomaterials for dye-sensitised solar cells

ABSTRACT Molybdenum disulphide (MoS2) nanotube and tungsten oxide (W18O49) nanowire were coated with poly(3-hexylthiophene) (P3HT) and poly(3,4-ethylenedioxythiophene) (PEDOT) by a radio frequency (RF: 13.56 MHz)-rotating plasma-modification method as alternative counter electrodes for dye-sensitised solar cells (DSSCs). Surface analysis showed the homogenous plasma nanocoating of inorganic nanostructures by P3HT and PEDOT. It was demonstrated that the plasma-modified hybrid platinum-free counter electrodes increased the efficiencies of the DSSCs. The DSSCs based on hybrid nanostructure materials showed a short circuit current density of 9.49, 7.95, 2.59 and 2.57 mAcm−2 for MoS2/P3HT, MoS2/PEDOT, W18O49/PEDOT and W18O49/P3HT samples, respectively. The plasma nanocoating with the nanostructured materials approach for obtaining hybrid counter electrodes in the photovoltaic action shows an alternative route towards cost-effective, green energy conversion.

Surface properties of radio frequency plasma treated wool and denim fabrics

Purpose The purpose of this paper was to investigate the effects of hydrochloric acid (HCl), hydrazine, methyl methacrylate, styrene and hexamethyldisiloxane by radio-frequency (rf) plasma graftings on surface properties of wool and denim fabrics. Design/methodology/approach During plasma treatments, processing time was varied under optimized plasma conditions (50 W, rf: 13.56 MHz). All fabrics were comprehensively investigated by means of scanning electron microscopy-energy dispersive X-ray spectroscopy and contact angle measurements. Findings The experimental data shows that the rf-plasma processing has important effect on the wettability properties of wool and denim fabrics. The results indicated that HCl plasma treatment significantly improves the hydrophilicity of wool and denim fabrics. Originality/value The research on wool and denim fabric treatment by plasma is original.

Atmospheric pressure plasma pen for surgical purposes

Atmospheric pressure cold plasmas are used in sterilization, cutting and coagulation without damaging living tissues and cells. The preliminary studies on the production of the plasma pen which will allow cutting and coagulation at lower temperature than the conventional electrosurgery methods are presented. Intended power supply, pen design and manufacture are made. The results related to the first in vitro experiments carried out by the pen are given.

Plasma help preparation of electrospun carbon nanofibers

This work reports the fabrication and characterization of polyacrylonitril (PAN) nanofibers by electrospinning and further development of the as-spun PAN nanofibers into carbon nanofibers by using plasma help carbonization process. PAN nanofibers as a precursor of carbon nanofibers were prepared by electrospinning of PAN/DMF solution. The aligned electrospun polyacrylonitrile (PAN) nanofibers were converted to carbon fibers under plasma conditions and high temperatures. Morphologies, structures and thermal properties of PAN, stabilized and carbonized nanofibers were investigated by scanning electron microscopy (SEM-EDS), infrared spectrometer (IR), thermal gravimetric analysis (TGA).

Inductively coupled plasma for graphene production

This study is investigating the direct growth of graphene on a membrane filter and a copper surface by injecting ethanol vapor into an inductively coupled plasma (ICP) at atmospheric pressure. Low temperature (<;1000) graphene production is possible by an ICP plasma [1]. The discharge chemical mechanism will be analyzed by optical emission spectrum. The effects of the temperature and the plasma power on graphene sheets will be analyzed by SEM, AFM and Raman spectra.