The electrochemical behaviors of non-peripherally tetra substituted zinc(II) and
magnesium(II) phthalocyanines were studied at glassy carbon electrode in N,N-dimethylformamide
using cyclic and square wave voltammetry techniques. Electrochemical mechanisms of complexes were
illuminated by using the relationship between scan rate and peak current. The complexes exhibited
reversible and diffusion controlled behaviors. The effect of metal center on redox properties of
complexes were investigated and compared. Zinc and magnesium phthalocyanines showed three
reduction redox pairs and one oxidation redox pair, which are similar with small differences in potential
during electrochemical measurements. Electrochemical results were supported with in-situ
spectroelectrochemical measurements. Moreover, the color changes were recorded and sharp color
transitions were observed during the reduction and oxidation redox processes.
|
The calcium carbonate (CaCO3) crystals were successfully synthesized in the presence of
glutamic acid used as an additive at 30 °C and at a pH of 8.5. The synthesized product was characterized in
detail by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy and scanning electron
microscopy (SEM) to identify the structure and habit of the crystals. Moreover, the size and surface charge
of the crystals were measured by particle size and zeta potential analyzer. XRD and FTIR results showed that
both calcite and vaterite in forms of apparently CaCO3 crystals were obtained in the presence of 50 ppm
additive concentration at t=30 min. When increasing the glutamic acid concentration in the suspension, the
formed CaCO3 were only in the vaterite form. The SEM analysis results pointed out that the addition of the
glutamic acid significantly changed the shape of the CaCO3. At t=30 min the resulting product sample was
found to contain two types of polymorphs; larger cubic shaped calcite crystals and smaller spherical-like
vaterite crystals. Further addition of high concentrations of the additive enhanced the adsorption of the
glutamic acid, resulting in the smaller spherical-like ellipsoidal vaterite crystals. Investigation of the zeta
potential analysis indicated that higher additive concentration (100 ppm) resulted in a positive surface
charge of the crystals, whereas lower concentration (50 ppm) gave negative electrical charge. Moreover,
filtration analysis pointed out that adding glutamic acid additive resulted in a less specific cake resistance
value (5.01 × 1011 m/kg) than that in pure media, which was 1.03 × 1012 m/kg.
|
Hirshfeld surface analysis, a suitable tool for investigating intermolecular interactions, has been
widely used in crystallography in recent years. A breakdown of related fingerprint graphics is presented as a
color chart, allowing a quantitative analysis of intermolecular interaction types. In this study, the
intermolecular interactions of diaqua-bis(4-cyanobenzoato-κO)bis(nicotinamide-κN
1
)cobalt(II) (I),
diaquabis(4-cyanobenzoato-κO)bis(nicotinamide-κN
1
)copper(II) (II), diaquabis(4-cyanobenzoatoκO)bis(nicotinamide-κN
1
)nickel(II) (III), triaqua(4-cyanobenzoato-κ
2O,O')(nicotinamide-κN)zinc(II) 4-
cyanobenzoate (IV), diaquabis(4-cyanobenzoato-κO)bis(N,N’-diethylnicotinamide-κN)cadmium(II) (V),
diaquabis(4-cyanobenzoato-κO)bis(N,N’-diethylnicotinamide-κN)zinc(II) (VI) and catena-poly[[aquabis(4-
cyanobenzoato-κO)copper(II)]-μ-N,N’-diethylnicotinamide-κ
2N
1
:O] (VII) complexes, crystal structures were
previously determined and investigated by using Hirshfeld surface analysis via CrystalExplorer Program
Version 17.5. In addition, the intermolecular interaction energies of the complexes were calculated using CEHF/3-21G and CE-B3LYP/6-31G (d,p) energy models that involved in CrystalExplorer (CE) software. Related
to the obtained Hirshfeld surface analysis results, H…H, H…C/C…H, H…O/O…H, H…N/N…H, C…C, C…N/N…C and C…
O/O…C constitute the intermolecular interactions of the complexes. Additionally, N…O/O…N and N…N
interactions only in I, II, III, IV and VII complexes, H...Cu/Cu...H, O...Cu/Cu...O only in complexes II and VII and
O
...O interactions only in complexes II, V and VI were also found. The most significant interactions of all of
the complexes were found as the H…H interactions. These results support the existence of π-π interactions
between benzene and pyridine rings and medium strength hydrogen bonds which contribute to the stability
of the crystal packing of the complexes that are determined by single crystal X-ray diffraction method.
Depending on the intermolecular interactions and the energy-framework analysis the O-H...O and N-H...O
hydrogen bonds, and π···π stacking and C−H···π interaction energies are the most significant forces in the
crystal packaging. The estimation of the intermolecular interactions and electrostatic energy values of the
complexes are very important for the classification of them for their electrical, magnetic and optical
properties.
|
In this study, total flavonoid substances, total phenolic substances, and total antioxidant capacity in
turnip juice which made from the turnip (Brassica rape), a plant belonging to the family of “Turpgiller”
(Brassicaceae), and also a drink specific to the Çukurova, were investigated. The turnip juice samples, taken
from the turnip juice (A sample) and hot turnip juice (B) sample in local market, prepared in the laboratory were
performed as two different parallel assays. In addition, electrochemical method was used to evaluate total
antioxidant capacity (TAC) of turnip juice and hot turnip juice. By the square wave stripping voltammetry
(SWSV) method, under the optimized experimental conditions was applied for quercetin determination with a
limit of detection (LOD) and limit of quantification (LOQ) of 0.017 and 0.057 µg/L, respectively. These values are
satisfactory for application to real food samples for the evaluation of TAC. According to the results carried out
by spectrophotometric methods, the highest total phenolic and flavonoid contents and TAC were observed as
13.049±0.40 g GAE/mL, 37.850±0.70 mg QE/mL and 81.831±3,24 mg TE/100 mL, respectively. In addition, the
TAC in turnip juice and hot turnip juice were calculated as 573.05±0.43 mg/L and 854.98±9.9 mg/L by SWSV,
respectively. The results obtained by voltammetric and spectrophotometric methods for determinations of TAC
were in correlation and found to be compatible for the determination of TAC.
|
Bisphenol A (BPA), which is an endocrine-disrupting substance, is often utilized as beverage and
food packing material, and it may accumulate in nutrition and water sources, which is why it is important to
monitor. In this study, for the determination of bisphenol A, electro-polymerization of glutamic acid (GA) was
performed on a pencil graphite electrode (PGE). The performance of the sensor (PGA/PGE) for determining
bisphenol A was examined utilizing the cyclic voltammetric (CV) and differential pulse voltammetric (DPV)
methods. Electrochemical characterization process of the PGA/PGE was carried out by the electrochemical
impedance spectroscopy (EIS) and CV methods. The morphological property of the PGA/PGE was
investigated by scanning electron microscopy (SEM). The presence of functional groups in the PGA/PGE
composition was characterized by Fourier transform infrared spectroscopy (FTIR). The electrochemical
behavior of BPA was observed with the bare PGE and the PGA/PGE. Based on the findings, the response of
BPA was considerably raised with PGA/PGE. With the optimized parameters and based on the findings from
DPV, the BPA oxidation current was linear in a concentration interval of 1.0 to 100 μM (R=0.9992), and the
detection limit was found to be 0.37 μM. Detection of BPA in the plastic bottled drinking water sample using
PGA/PGE was performed successfully, and the recoveries were in the range of 89.3 to 104.7%. This strategy
can provide several prospects in electrochemically determining BPA in practical applications.
|
Activated carbon derived from Balanites aegyptiaca seed shell (ACBS) was employed to remove
crystal violet (CV) from aqueous medium. The characterization of this ACBS has been conducted using analytical
techniques such as SEM, EDS, and Brunauer-Emmett-Teller (BET) surface area analysis. The adsorption
parameters investigated were as follows: contact time (5-120 min), temperature (303-333 K) and initial
concentration (100-500 mg/L). The adsorption data were interpreted by using kinetic, isotherms and
thermodynamic equations. The kinetic data matched the pseudo-second-order model well, and both external
diffusion and internal diffusion influenced the adsorption of the dye onto the adsorbent. The isotherm data was
in concurrence with the Freundlich model intimating the multilayer coverage of CV on the heterogeneous
surface of the ACBS. The thermodynamic quantities like ∆S°, ∆H° and ∆G° were computed using Gibbs plot. The
results implicated the practicability and endothermicity of the dye adsorption process. Regeneration studies
show the effectiveness of CH3COOH solution in CV recovery from ACBS than distilled water, H2SO4, HCl, HNO3,
and NaOH solutions. The regenerated ACBS was recycled five times and sustained an adsorption efficiency of
92.08%.
|
Herein, the synthesis of the macroaggregated albumin particles was carried out under
different conditions for the size optimization that can be used in magnetic resonance, positron
emission and fluorescence imaging. The size distribution analysis was performed with the
Mastersizer and optimized MAA had 31.57 µm size and 0.36 PDI value. Morphological analysis was
done with SEM. EDX and FT-IR analyzes were performed to study formed Eu3+ and Tb3+ complexes
with optimized MAA. MAA complexes that can be used in lungs and liver imaging have been
successfully obtained.
|
The Alphabet Reform painting which shows Ataturk teaching the new alphabet is important for
the history of the Republic of Turkey. This painting was made by Nazmi Ziya GÜRAN in 1933. The painting is
now maintained by the Ministry of Interior. In this work, the Alphabet Reform painting was analyzed for
characterization and restoration purposes. The fabric of the canvas, pigments (organic-inorganic) and the
binder of paint were characterized by Fourier Transform infrared spectroscopy-attenuated total reflectance
(ATR-FTIR), scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDX) and highperformance liquid chromatography-coupled with diode array detection (HPLC-DAD) analysis methods. The
CIEL*a*b* color parameters of the paint were determined by color measurement spectrophotometer.
According to the results, the canvas was found to be of fibers of vegetable origin and the binders were
determined to be linseed oil and dammar varnish. Red alizarin (madder lake organic pigment) and dark blue
ultramarine pigments were detected as the organic pigments while CdS (yellow), Pb red (flesh color), PbCO3
(white), ZnO (white), BaSO4 (white), FeO (brown) and Cr2O3 (green color) were detected as the inorganic
ones.
|
The selection of the best mobile phase setup is one of the most important factors to be
considered prior to quantitative instrumentation of multiple pesticides. Usually, mobile phases comprises of
water (A) and an organic solvent (B) are the setup used in liquid chromatography instruments for the
analysis of pesticide residues in various samples. Unfortunately, most of the analyses are being carried out
without optimization and selection of the best mobile phase setup to improve the sensitivity of the
instrument. For that reason, the comparative analysis of the reportedly used mobile phases and some few
suggested ones was carried out on the multi-pesticide mixture of 0.1 mg/kg (100 µg/kg) standard solutions
and quantified with liquid chromatography-tandem mass spectrometry (LC-MS/MS) instrument.
Consequently, the best mobile phases setup that resulted in the sum of average total chromatographic peak
areas (ATCPAs) and average total chromatographic peak heights (ATCPH) for the total ion chromatography
(TIC) scans as an index that correspond to the concentration levels was selected [0.1% formic acid in H2O
(A) and 0.1% formic acid in acetonitrile (ACN) (B)]. And further optimization was successfully carried out on
the selected mobile phase-A and the resulted setup [1% ACN and 0.1% formic acid in Milli-Q-water (mobile
phase A) coupled with 0.1% formic acid in ACN (mobile phase-B)] improved the instrumental sensitivity on
the targeted analytes. Thus, this justify the potential benefits of optimizing setup of the mobile phases prior
to LC-MS/MS instrumentation of multi-pesticide analytes.
|
In this study, the hydroxyl groups of cellulose acetate butyrate (CAB) oligomer were reacted with
toluene diisocyanate-hydroxyethyl methacrylate (TDI-HEMA) adduct, in order to improve properties of CAB
such as flexibility, thermal stability, etc. Then the obtained modified CAB oligomer was characterized by FTIR
and 1H NMR analysis. UV-curable coating formulations were prepared by using the modified CAB oligomer,
and then applied on cotton fabrics in order to reinforce cotton fabrics and make them durable in outdoor
environments. Cotton fabrics were treated with a commercial washing detergent, alkaline solution, and an
enzyme prior to the UV-coating, in order to increase the adhesion between the cotton fabric and coating
layer. Washed and coated fabrics were evaluated in terms of absorbency, tensile, and adhesion properties,
respectively. Light microscopy was employed to observe the effects of washing processes on fiber, and to
show the abrasion deformation on coated fabric. Results proved that the best washing process in fibrillation
was found as enzymatic washing due to the highest adhesion strength and the least deformation against
abrasion.
|
