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Ion/Ioff Ratios (ion + ratio)
Selected AbstractsThe effect of oxygen remote plasma treatment on ZnO TFTs fabricated by atomic layer depositionPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 8 2010Seungjun Lee Abstract We deposited ZnO thin films by atomic layer deposition (ALD) and then investigated the chemical and electrical characteristics after plasma treatment. The chemical bonding states were examined by X-ray photoelectron spectroscopy (XPS). The XPS spectra of O 1s showed that the intensity of oxygen deficient regions of the ZnO film decreased from 27.6 to 19.4%, while the intensity of the oxygen bound on the surface of the ZnO film increased from 15.0 to 21.9% as plasma exposure times increased. The ZnO film exhibited a decrease in carrier concentration from 4.9,×,1015 to 1.2,×,1014,cm,3 and an increase in resistivity from 1.2,×,102 to 9.8,×,103,,,cm as the plasma exposure times increased. To verify the changes in the chemical and electrical properties of the ZnO films caused by the oxygen remote plasma treatment, ZnO thin film transistors were fabricated and their electrical properties were investigated. We found that the Ion/Ioff ratio increased from 7.3,×,104 to 8.6,×,106, the subthreshold swings improved from 1.67 to 0.45,V/decade, and the saturation mobility (µsat) decreased from 1.63 to 0.72,cm2/V,s as plasma exposure times were increased. [source] Thiophene,Benzothiadiazole Co-Oligomers: Synthesis, Optoelectronic Properties, Electrical Characterization, and Thin-Film PatterningADVANCED FUNCTIONAL MATERIALS, Issue 3 2010Manuela Melucci Abstract Newly synthesized thiophene (T) and benzothiadiazole (B) co-oligomers of different size, alternation motifs, and alkyl substitution types are reported. Combined spectroscopic data, electrochemical analysis, and theoretical calculations show that the insertion of a single electron-deficient B unit into the aromatic backbone strongly affects the LUMO energy level. The insertion of additional B units has only a minor effect on the electronic properties. Cast films of oligomers with two alternated B rings (B,T,B inner core) display crystalline order. Bottom-contact FETs based on films cast on bare SiO2 show hole-charge mobilities of 1,×,10,3,5,×,10,3,cm2 V,1s,1 and Ion/Ioff ratios of 105,106. Solution-cast films of cyclohexyl-substituted compounds are amorphous and do not show FET behavior. However, the lack of order observed in these films can be overcome by nanorubbing and unconventional wet lithography, which allow for fine control of structural order in thin deposits. [source] Synthesis of star-shaped molecules with pyrene-containing ,-conjugated units linked by an organosilicon coreAPPLIED ORGANOMETALLIC CHEMISTRY, Issue 8 2010Joji Ohshita Abstract Star-shaped molecules with pyrene-containing ,-conjugated units linked by an organosilicon core (Py3Si and Py3C) were prepared and their applications to thin-film transistors (TFTs) and photovoltaic cells were studied. Bottom-contact type TFTs with spin-coated films of the star-shaped compounds as the active layers were prepared and the field-effect mobility (µFET) and Ion/Ioff ratios were determined to be approximately 10,5 cm2 V,1 s,1 and 104, respectively. Photovoltaic properties of Py3Si and Py3C were studied in the cells, ITO,PEDOT-PSS,Py3Si or Py3C-PCBM,LiF,Al. Although the power conversion efficiency (PCE) of the cells was only about 0.04%, they showed high open circuit voltages (Voc) of 0.8,0.9 V, indicating the high potential of this type of compound as a host material. Copyright © 2009 John Wiley & Sons, Ltd. [source] Comparison of analytical approaches for liquid chromatography/mass spectrometry determination of the alcohol biomarker ethyl glucuronide in urineRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 12 2010Anders Helander Official guidelines originating from a European Union directive regulate requirements for analytical methods used to identify chemical compounds in biological matrices. This study compared different liquid chromatography/electropray ionization mass spectrometry (LC/ESI-MS) and tandem mass spectrometry (LC/ESI-MS/MS) procedures for accurate determination of the conjugated ethanol metabolite and alcohol biomarker ethyl glucuronide (EtG) in urine, and the value of combined EtG and ethyl sulfate (EtS) measurement. Analysis was carried out on 482 urines following solid-phase extraction (SPE) sample cleanup or using direct injection of a diluted sample. SPE combined with LC/MS/MS was demonstrated to be the most selective and sensitive method and was chosen as reference method. The EtG results by different methods showed good correlation (r,=,0.96,0.98). When comparing five reporting limits for EtG in the range 0.10,1.00,mg/L, the overall agreement with the reference method (frequency of true positives plus true negatives) was 82,97% for direct-injection LC/MS/MS, 90,97% for SPE-LC/MS, 86,98% for direct-injection LC/MS, and 86,98% for direct-injection LC/MS analysis of EtG and EtS. Most deviations were attributable to uncertainty in quantitation, when the value was close to a cutoff but the respective results were slightly above and below, or vice versa, the critical limit. However, for direct-injection LC/MS/MS, despite earning 4 identification points, equally many negative results were due to a product ion ratio outside the ±20% deviation accepted by the guidelines. These results indicate that the likelihood of different analytical methods to provide reliable analytical results depends on the reporting limit applied. Copyright © 2010 John Wiley & Sons, Ltd. [source] False-positive liquid chromatography/tandem mass spectrometric confirmation of sebuthylazine residues using the identification points system according to EU directive 2002/657/EC due to a biogenic insecticide in tarragonRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 8 2009Andreas Schürmann In pesticide residue analysis using liquid chromatography/tandem mass spectrometry (LC/MS/MS) the confirmation of a sebuthylazine finding in a tarragon (Artemisia dranunculus) sample was demonstrated to be false positive. A coeluting interfering matrix compound produced product ions in MS/MS analysis, perfectly corresponding to the multiple reaction monitoring (MRM) of two sebuthylazine transitions. Using the EU directive 2002/657/EC which regulates the confirmation of suspected positive findings would have resulted in a false-positive finding. A third LC/MS/MS transition with a deviant ion ratio and a gas chromatography (GC)/MS/MS analysis revealed the false-positive results. With optimized high resolving ultra-performance liquid chromatography (UPLC) conditions it was possible to separate spiked sebuthylazine from the interfering matrix compound. Using its exact mass and isotope ratios from LC/time-of-flight (TOF) MS measurements, the compound was identified as nepellitorine, a , not surprising , endogenous alkamide in tarragon (Arthemisia dranunculus). False-positive results, especially in heavy matrix samples such as herbs, can be dealt with by further confirmatory analysis, e.g. a third transition, GC analysis if possible or more advantageous by an orthogonal criterion like exact mass. Copyright © 2009 John Wiley & Sons, Ltd. [source] Strontium isotopic characterization of the Palmottu hydrosystem (Finland): water,rock interaction and geochemistry of groundwatersGEOFLUIDS (ELECTRONIC), Issue 3 2003Philippe Negrel Abstract The Palmottu hydrosystem is located in a granitic host rock in southern Finland. Along well-defined pathways in the fractured crystalline rock, strontium isotopes are used to trace the degree of water,rock interaction (WRI) and mixing processes in groundwaters. The 87Sr/86Sr ratios range between 0.716910 and 0.735606 in the surface waters and between 0.719991 and 0.750787 in the groundwaters, but are between 0.720 and 0.735 in most of the samples. Moreover, the results show a lack of correlation between the water chemistries determining the classification into different water-types (Na,Cl, Na,SO4, etc.) and the results of the strontium (Sr) contents and Sr isotopic ratios. From a WRI standpoint, this implies that the Sr behaviour is independent of the water chemistry; the occurrence of large 87Sr/86Sr variations is site specific and mainly dependent on the lithology. A model to determine the 87Sr/86Sr ratio of water after interaction with granite was developed. This model is based on the assumption that Sr was derived from three minerals: plagioclase, K-feldspar and biotite. The results of the calculation indicate that around half of the water analysed within the Palmottu hydrosystem can be explained by the weathering of the granites. However, clearly lower 87Sr/86Sr are observed in waters when compared to the calculated 87Sr/86Sr and other sources of Sr, with low 87Sr/86Sr, rather than the calculated granite,water interaction, which may be suspected. When comparing the 87Sr/86Sr and ion ratios (Ca/Na, Mg/Na, Sr/Na, Cl/Na), the scattering of the data can be explained by the presence of four end-members: a brine component (low 87Sr/86Sr and Ca/Na ratios,), a deep granitic component (high 87Sr/86Sr ratios and low Ca/Na ratios,), a subsurface component (intermediate 87Sr/86Sr ratios associated with high Ca/Na ratios,) and a surface end-member:snow and river drainage (low 87Sr/86Sr and low Ca/Na ratios,). These extreme end-members define a series of WRI-mixing line within a rather complex hydrosystem. [source] An investigation into the dynamics of chalcopyrite bioleachingAICHE JOURNAL, Issue 10 2010Athanasios Kotsiopoulos Abstract A study was undertaken to investigate the dynamics of chalcopyrite bioleaching. The analysis revealed significant dynamics features because the chemical leaching rate of chalcopyrite does not vary monotonically with solution redox potential but undergoes a maximum followed by a minimum as potential increases. The analysis does account for reaction passivation, an effect that has consistently been reported in the literature. The existence and stability of steady states were determined as functions of the solution redox potential, reactor temperature, and biomass concentration. It was found that the rate of bioleaching increased with temperature at lower overall solution potentials with competitive rates observed at high ferric/ferrous ion ratios. Both high and low overall bioleaching rates were observed with increasing biomass concentration, indicating an upper concentration limit before passivation. These results indicate that the frequently observed inhibiting rates may simply be artifacts of the system dynamics rather than due to physical phenomena. © 2010 American Institute of Chemical Engineers AIChE J, 2010 [source] | ||||||||||