A Novel MPTHP Modified Glassy Carbon Sensor Electrode: Investigation of Electrochemical Behaviors and Determination of Cu (II) Ions in Drinking Water Sample

In the present work report, 2-methyl-6-((2-(4-(3-methyl-3-phenylcyclobutyl)thiazol-2-yl)hydrazono)methyl) phenol (MPTHP) has been newly synthesized and characterized. The new molecule has been used to modify the glassy carbon (GC) electrode surface through the alcohol oxidation method due to –OH group on its structure. MPTHP modified GC (MPTHP/GC) electrode has been used as a chemical sensor electrode for the quantitative determination of Cu (II) ions. Following the modification process, the surface characterization process of the modified electrode has been carried out by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and scanning electron microscopy (SEM). In this work, Cu (II) ions have been quantitatively determined by using differential pulse voltammetry (DPV) technique. A quite low detection limit (based on 3sbl/m) for Cu (II) using developed sensor electrode was found to be as 1.0x10-9 M. For the calibration curve, solutions of Cu (II) ions changing from 1.0x10-9 M to 1.0x10-3 M have been prepared using Britton-Robinson (BR) buffer solution at pH 5. The developed sensor electrode has been applied to tap water sample for the quantitation of Cu (II) ions and the amount of Cu (II) was determined as 4.07 x 10-9 M in this sample

Analysis of variance and linear contrasts in experimental design with generalized secant hyperbolic distribution

We consider one-way classification model in experimental design when the errors have generalized secant hyperbolic distribution. We obtain efficient and robust estimators for block effects by using the modified maximum likelihood estimation (MML) methodology. A test statistic analogous to the normal-theory F statistic is defined to test block effects. We also define a test statistic for testing linear contrasts. It is shown that test statistics based on MML estimators are efficient and robust. The methodology readily extends to unbalanced designs

Synergistic effect of boron containing substances on flame retardancy and thermal stability of intumescent polypropylene composites

The synergistic effect of four different boron containing substances, zinc borate (ZnB), borophosphate (BPO4), boron silicon containing preceramic oligomer (BSi) and lanthanum borate (LaB), were studied to improve the flame retardancy of a polypropylene (PP) intumescent system composed of ammonium polyphosphate (APP) and pentaerythritol (PER). The flame retardancy of PP composites was investigated by limiting oxygen index (LOI). UL-94 standard, thermogravimetric analysis (TGA) and cone calorimeter tests. The addition of 20 wt% intumescent flame retardant (IFR) improves the flame retardancy by increasing the char formation. According to LOI and UL-94 test, boron compounds show their highest synergistic effect at I wt% loading. BPO4 containing composite shows the highest LOI (30), lowest maximum heat release rate (HRR) and lowest total heat release rate (THR) value. Although the char yield increases as the amount of boron compounds increases, the flame retarding effect decreases. Cone calorimeter and TGA data indicate that the boron compounds are likely to show their synergistic effect by reinforcing the integrity of char which improves its barrier effect rather than increasing the char yield. (C) 2010 Published by Elsevier Ltd

Effect of boron containing materials on flammability and thermal degradation of polyamide-6 composites containing melamine cyanurate

Three different boron containing materials, zinc borate (ZnB), borophosphate (BPO(4)), and boron and silicon containing oligomer (BSi), were used to improve the flame retardancy of melamine cyanurate (MC) in a polyamide-6 (PA-6) matrix. The combustion and thermal degradation characteristics were investigated using limiting oxygen index (LOI), UL-94 standard, thermogravimetric analysis-Fourier transform infrared spectroscopy (TGA-FTIR), differential scanning calorimeter (DSC), and scanning electron microscopy (SEM). All the three boron compounds showed no synergistic effect with MC, and only BPO(4) at high loadings showed comparable LOI values by increasing the dripping rate. For ZnB and BSi glassy film and char formation decreases the dripping rate and sublimation of melamine and give rise to low LOI. According to TGA-FTIR results, addition of boron compounds does not alter the gaseous product distribution of both MC and PA-6. The addition of boron compounds affects flame retardancy through physical means. It was noted from the TGA data that boron compounds reduced the decomposition temperature of both MC and PA-6, also affecting the flame retardancy negatively by premature degradation of MC at low temperatures. Copyright (C) 2009 John Wiley & Sons, Ltd

Long term impact of dissolved dispersed petroleum hydrocarbons (DDPH) in Gulf of Iskenderun

DDPH in sea water, polyaromatic hydrocarbons (PAH's) in sediment and in some marine biota were monitored for the period of August 1981 and April 1984. Maximum DDPH was measured in winter and minimum in summer. This phenomena showed an inverse relation with the sea water temperature. Increase in sea water DDPH concentration reflected itself immediately in fish liver but two months time lack between fish liver and flesh was observed. GLC analysis results of sea water extracts and various crude oil showed that the petroleum hydrocarbons in the Gulf was mainly originated from Kirkuk crude oil.Publisher's Versio

Phytoplankton biomass, primary production and chemoautotrophic production of the Western Black Sea in April 2003

The multilayered surface waters of the Black Sea contain aerobic, suboxic and anoxic layers that support both photoautotrophic (PP) and chemoautotrophic (ChP) biological production. During the R/V Knorr cruise from 15 to 25 April 2003, phytoplankton biomass (represented as chlorophyll-a), photoautotrophic and chemoautotrophic production (ChP) rates were determined in the southwestern Black Sea. Surface CM-a concentrations ranged from 0.06 and 0.62 ug/1 for the whole study area. These low values suggest post-bloom conditions. Integrated chlorophyll-a concentrations in the euphotic zone were as low as 2.4 mg m(-2) in the central gyre, while they were as high as 22 mg m(-2) in the Rim current. Integrated photoautotrophic production rates ranged from 70 to 664 mgC m(-2) d(-1). The lowest values were observed in the western central gyre and the highest values were found at the regions around Sakarya Canyon. Integrated ChP rates were 282 and 1013 mgC(-2) d(-1), which were equivalent to 45% and 83% of the overall water-column production for the central gyre and Rim current regions, respectively. Maximum rates are observed in the upper layer of the sulfide zone. The highest values of integrated ChP were in the vicinity of the Sakarya shelf and Rim current region. Extremely high values of ChP can occur in the Black Sea and appear to be driven by oxygen ventilation and redox cycling

Strontium doped hydroxyapatite biomimetic coatings on Ti6Al4V plates

Titanium (Ti) and its alloys are the most attractive metallic biomaterials since their first introduction to the biomedical area. Their major drawback is that they do not promote complete osteointegration due to their low bioactivity; thus, it is necessary to perform a surface treatment or apply a surface coating to increase the initial formation of surrounding bone tissue. In this study, strontium (Sr)-doped hydroxyapatite (HA) coatings on Ti6Al4V substrates were prepared by biomimetic method in which 2 times concentrated simulated body fluid (2xSBF) solution was used as the apatite growth medium. The characterization studies with X-ray diffraction (XRD) and scanning electron microscopy (SEM) indicated that as the amount of strontium ion (Sr2+) replacing with calcium ion (Ca2+) in the structure increases, crystallinity decreases without causing a significant change in morphology of the HA deposits. Incorporation of Sr2+ ions resulted in the disappearance of Fourier transform infrared (FTIR) bands of carbonate ion (CO32-) which was found in the structure of pure HA biomimetic coating. The biological results demonstrated that Sr-doped HAs presented no cytotoxicity on Saos-2 cells. This study showed that the incorporation of Sr into apatitic structure is possible by mimicking the natural route and this procedure yields a promising bioactive coating on Ti alloys to be used in bone replacement therapies especially associated with osteoporosis

Surface Characterization and Biocompatibility of Selenium-Doped Hydroxyapatite Coating on Titanium Alloy

Selenium-doped hydroxyapatite (HA) was biomimetically coated on Ti6Al4V plates with the aim of combining the anticancer and antibacterial properties of selenium with the biocompatibility and bioactivity of HA. For the coating process, the composition of 1.5 x SBF (solution with ion concentrations at 1.5 times that of simulated body fluid, SBF) was modified to include 0.15 mM selenate (SeO42-) ion. The selenium-doped HA coating was characterized by several methods, such as scanning electron microscopy, X-ray diffraction, and Fourier transform infrared spectroscopy. The cytotoxicity of selenium on osteoblast and osteosarcoma cells was determined. The coating was shown to inhibit the growth of Staphylococcus epidermidis