New phosphine-amino-alcohol tridentate ligands for ruthenium catalyzed asymmetric transfer hydrogenation of ketones
Altan, Orhan | Yılmaz, Mustafa Kemal
New phosphine-amino-alcohol tridentate ligands (3a-c) and six new ruthenium complexes (4a-c and 5a-c) were synthesized and characterized. Catalytic activities of the metal complexes were tested on aryl alkyl ketones. All of the substrates were converted to related sec-alcohols in excellent yields (up to 99%), but enantioselectivities were insufficient (up to 40% ee). Despite the catalytic performance of 5a-c complexes can be considered as better than 4a-c, actually the catalytic activity of the complexes has been differed according to substrate. The ketones with less positive carbonyl carbons tend to give S-configuration with 5a-c and R-configuration with 4a-c. The catalytic performance of the complexes was rationalized by means of DFT calculations.
Nanostructured Photocatalysts Chapter 15 - Black phosphorus-based photocatalysts for energy and environmental applications
Altan, Orhan
Photocatalysis using semiconductor materials to conduct chemical reactions more efficiently with the aid of sunlight irradiation is foreseen as a promising solution to combat the energy and environmental pollution crisis that the world is facing at present. Finding a suitable semiconductor material that harvests a large portion of the sunlight spectrum with high photocatalytic efficiency lies in the heart of photocatalysis. In this regard, black phosphorus (BP), a rising star two-dimensional (2D) semiconducting material, has recently been regarded as an abundant, nontoxic, metal-free, and cheap photocatalyst with a suitable bandgap and broad light absorption ability. In this chapter, after the introduction of the general properties and synthesis of BP, the photocatalytic efficiency of BP a...
Boosting formic acid dehydrogenation via the design of a Z-scheme heterojunction photocatalyst: The case of graphitic carbon nitride/Ag/Ag3PO4-AgPd quaternary nanocomposites
Altan, Orhan
The development of an efficient, eco-friendly, practical, and selective way to decompose formic acid (FA) into H2 and CO2 is crucial for the utilization of FA as a chemical hydrogen storage material in hydrogen economy. In this regard, photocatalytic FA dehydrogenation attracts great attention owing to its potential to meet the above-mentioned requirements. Interestingly, there is no example of heterojunction photocatalyst that tunes the hole potential of the semiconductor, resulted in a better photocatalytic activity. We report herein for the first time the design and fabrication of a novel Z-scheme heterojunction photocatalyst for FA dehydrogenation, denoted as g-CN/Ag/Ag3PO4-AgPd comprising graphitic carbon nitride (g-CN) and Ag3PO4 semiconductors, Ag and AgPd alloy nanoparticles (NPs)....
The influence of band bending phenomenon on photocatalytic Suzuki-Miyaura coupling reaction: The case of AgPd alloy nanoparticles supported on graphitic carbon nitride
Altan, Orhan
The development of solar-powered systems for applications other than energy, such as photocatalytic organic reactions, will benefit in the resolution of environmental issues while also lowering production costs. In this study, the photocatalytic activity of g-CN(G)-AgPd, which was prepared by synthesizing AgPd alloy nanoparticles (NPs) on g-CN, was investigated in the Suzuki-Miyaura coupling (SMC) reaction. The photocatalytic activity of g-CN(G)-AgPd in an ethanol/water mixture at ambient temperature was discovered to be among the highest ever recorded. Under vis-light illumination, g-CN(G)-AgPd converted all of the aryl iodides and most of the aryl bromides investigated to desired coupling products in 15 min with excellent isolated yields, and it was used at least five times without signi...
The rational design of a graphitic carbon nitride-based dual S-scheme heterojunction with energy storage ability as a day/night photocatalyst for formic acid dehydrogenation
Altan, Orhan
Photocatalytic formic acid dehydrogenation (FAD) has been regarded as one of the most promising methods of producing H2 in a sustainable manner. In the photocatalytic FAD reaction, photogenerated holes play an important role in the reaction mechanism and thus in the efficiency of photocatalysts. However, the design of photocatalytic systems capable of generating high hole potential without compromising the reducing ability of the photocatalyst is extremely rare for the FAD reaction. In this respect, we report herein a novel and highly efficient heterojunction photocatalyst composed of 2D graphitic carbon nitride, 2D MnO2, 1D MnOOH, and 0D PdAg alloy nanoparticles, denoted as GCN/MnO2/MnOOH-PdAg, that can create high reduction and oxidation potentials via a dual S-scheme heterojunction. The...
Development of Fe2O3 based catalysts to control pollutant emissions in diesel engines
Resitoglu, Ibrahim Aslan | Yıldırımcan, Saadet
Exhaust after treatment systems have become a necessity to eliminate pollutant emissions as required by standard. Nowadays, DOC and SCR are widely used after treatment technologies in diesel vehicles. In this experimental study carried on DOC and SCR systems, two different catalysts as Al2O3-TiO2/Fe2O3 and Al2O3-Pt/Fe2O3 were produced with impregnation method. The catalysts were characterized by Field Emission-Scanning Electron Microscope (FE-SEM), X-ray diffraction (XRD), X-ray fluorescence (XRF) and Brauner-Emmett-Teller (BET). Each catalyst was tested as DOC and SCR in real working state to see the effect of catalyst on pollutant emissions in diesel engine. Results showed that the use catalysts as DOC led to significant decrease in CO, HC, NO and smoke emissions. The exhaust temperature...
Effect of cholesterol loaded cyclodextrin on semen cryopreservation of Aksaray Malakli shepherd dogs of different ages
Tuncer, Purhan Barbaros | Buyukleblebici Serhat
The objective of the study was to determine the effect of cholesterol-loaded cyclodextrin (CLC) on the quality parameters of semen from Aksaray Malakli Shepherd dogs of different age groups. Forty-eight male dogs were divided into 3 groupings according to their ages (young age (Y): ≤3years, n: 20; middle age (M): 4–6 years, n: 20; old age (O): ≥7 years; n: 8). The sperm-rich portion of the ejaculate from each dog was divided into four aliquots and extended with either tris as a control (C) or tris loaded with 0.5, 1.0, and 1.5mg/120×106 CLC as low (L), intermediate (I), and high (H) doses, respectively. Following equilibration for at least half an hour, the straws were frozen in nitrogen vapor and then stored in liquid nitrogen at least for 48h. Later, the frozen straws were thawed in a wa...
The effect of cysteine and glutathione on sperm and oxidative stress parameters of post-thawed bull semen
Tuncer, Pürhan Barbaros | Büyükleblebici, Serhat
The aim of this study was to determine the effects of antioxidants such as reduced glutathione (GSH) and cysteine in Laiciphose extender on semen parameters, fertilizing ability, lipid peroxidation (LPO) level and glutathione peroxidise (GPx) activity of post-thawed bull semen. Totally 54 ejaculates of three bulls were used in the study. Five groups, namely; GSH (0.5 and 2 mM), cysteine (5 and 10 mM) and control group, were conducted to test the antioxidants in Laiciphose . Insemination doses were processed that each 0.25-mL straw contained 15 106 sperm. The addition of antioxidants did not present any significant effect on the percentages of post-thaw sperm morphology (acrosome and total abnormalities), subjective, CASA and progressive motilities, as well as sperm motility characteristics...
Comparing ethylene glycol with glycerol and with or without dithiothreitol and sucrose for cryopreservation of bull semen in egg-yolk containing extenders
Büyükleblebici, Serhat | Tuncer,, Pürhan Barbaros | Büyükleblebici, Olga
There are few studies performed for investigating the roles of different ratio and cryoprotectants with dithiothreitol or sucrose on sperm motility characteristics and antioxidant capacities of post-thawed bull spermatozoa. The objectives of this study were to compare glycerol (G) and ethylene glycol (EG) at different concentrations as cryoprotectants and dithiothreitol (D) or sucrose (S) (with/without) as antioxidants in Tris extender for cryopreservation of bull semen. Twenty-four ejaculates obtained from three bulls were included in the study. Each ejaculate was split into four equal aliquots and diluted using both of the Tris extenders with glycerol (5% or 7%) or ethylene glycol (3% or 5%). After that, each extenders were split into three equal aliquots and diluted using both of the d...
Low cost measurement setup based on a piezoelectric microphone for estimating apple bruising using Shannon entropy
Demir, Bünyamin
This study presents a low cost measurement setup for estimating apple bruise volume during drop impact tests. The proposed measurement system consists of three main stages namely recording impact sound, signal processing, and estimating bruise volume. In the recording stage, the impact sound occurred when striking the apple on the surface was recorded by a piezoelectric microphone into computer. The impact sound was converted into Shannon entropy signals based on the Kernel density approach, and two measurable quantities namely entropy peak and pulse-width time were extracted from Shannon entropy signals in the signal processing stage. In the bruise volume estimating stage, the regression curves that map entropy peak and pulse-width features into bruise volume are estimated using measureme...
Adsorption of Malachite Green on Fe-modified biochar: influencing factors and process optimization
Gözmen, Belgin
Paper sludge and wheat husk biochar was converted to a Fe-composite through a simple coprecipitation process and its adsorption behavior was tested against an emerging pollutant, Malachite Green (MG). Response surface methodology was employed to determine the optimum experimental conditions and the interactions between pH, initial MG concentration, temperature and treatment time. The maximum adsorption percentage obtained experimentally was 97.1%, whereas the Box– Behnken design predicted a maximum adsorption of 98%, at pH 6.16, initial MG concentration of 6.56 ppm, temperature of 34.75°C and treatment time of 22 min. Compared with the original biochar, the Fe-modified sample improved the adsorption of MG by ~34%. The adsorption mechanism followed the Langmuir model (qmax = 172.3 mg/...
Valorization of loquat seeds by hydrothermal carbonization for the production of hydrochars and aqueous phases as added-value products
Gözmen, Belgin | Görmez, Özkan | Saçlı, Barış | Çalhan Doğan, Selda
In the framework of circular bio-economy, waste loquat seeds were utilized for the production of two addedvalue products. The seeds were hydrothermally carbonized at a temperature range of 150–250 ◦C and time range 2–6 h and the resultant hydrochars and aqueous phases were characterized using various methods. The optimum higher heating value of 30.64 MJ kg− 1 , ash content of 1.99 wt % and alkali index of 0.05 were achieved for the hydrochar prepared at 250 ◦C and 6 h, establishing its suitability for energy-related applications. The aqueous phase obtained at 250 ◦C and 6 h achieved 90% scavenging of the 2,2-diphenyl-1-picryl-hydrazyl-hydrate (DPPH) radical and had a IC50 value of 43.71 μg mL− 1 . Principal component analysis showed that the production of phenols, ketones, alkenes a...
Electrolysis of coal slurries to produce hydrogen gas: Relationship between CO2 and H2 formation
Gözmen, Belgin
The purpose of this study was to produce hydrogen gas by electrolysis of coal slurries and to investigate the relation between hydrogen (H2) and carbon dioxide (CO2) formation. Electrolysis of coal slurries was evaluated at 40 °C and 1.0 V cell potential to examine H2 and CO2relationship. When electrolysis was performed after the coal slurry was mixed with Fe(II)/Fe(III) ions and stirred overnight (>12 h), no CO2 gas was observed at the anode compartment. The results of total organic carbon (TOC) indicated that after electrolysis, few organic compounds were transformed into the solution and these organic compounds did not convert into CO2. GC analysis, on the other hand, revealed that the H2 collected at the cathode was pure and did not require any further purification process. Hydrogen ge...
Fe-modified sporopollenin as a composite biosorbent for the removal of Pb2+ from aqueous solutions
Gözmen, Belgin
The role of Fe-modified sporopollenin (Fe-Sp) biomass in Pb2+ removal from aqueous solutions was investigated by batch biosorption technique. The prepared biosorbent was characterized by scanning electron microscopy, energy-dispersive X-ray spectrometry, and Fourier transform infrared spectroscopy. The influence of pH, contact time, biosorbent dose, and initial concentration on biosorption process were optimized by using a four factor Box–Behnken design combined with response surface methodology. The results indicated a positive adsorption behavior of Fe-Sp and a strong pH dependency of the process. The optimum predicted parameters were determined as follows: biosorbent dosage 0.5 g, pH of 6.75, contact time 104 min, and initial Pb2+ concentration of 25.42 ppm. The Freundlich isotherm mode...
Effects of hypotaurine, cysteamine and aminoacids solution on post-thaw microscopic and oxidative stress parameters of Angora goat semen
Tuncer, Pürhan Barbaros
This study was conducted to determine the effects of cysteamine, hypotaurine and aminoacids solution (BME) on standard semen parameters, lipid peroxidation and antioxidant activities of Angora goat semen after the freeze–thawing process. Ejaculates collected from four Angora goats were evaluated and pooled at 37 C. Semen samples, which were diluted with a Tris-based extender containing the antioxidants hypotaurine (5 mM) and cysteamine (5 mM), and an aminoacid solution (13%), and an extender containing no antioxidants (control), were cooled to 5 C and frozen in 0.25-ml French straws in liquid nitrogen. Frozen straws were thawed individually at 37 C for 20 s in a water bath for evaluation. Supplementation with cysteamine, hypotaurine and BME caused significant (P < 0.05) increases in sper...
Enhancement of photocatalytic activity of carbon nitride/black phosphorus/tungsten disulfide (CN/BP/WS2) heterojunctions via nickel doping in the hydrogen evolution reaction
Altan, Orhan
The complementary properties of mesoporous graphitic carbon nitride (m-CN) and black phosphorus (BP) as non-metallic semiconductors offer many opportunities for the rational design of efficient photocatalysts for the photocatalytic hydrogen evolution reaction (HER). However, pristine m-CN and BP exhibit significant photoinduced charge carrier recombination rates and weak light absorption, resulting in a low photocatalytic HER activity. To overcome these problems and improve their photocatalytic HER activities, rational design of heterojunctions is one of the most efficient ways. Here, we present for the first time the ternary m-CN/BP/WS2 dual S-scheme heterojunctions, prepared by combining as-prepared m-CN/BP hybrids with tungsten disulfide (WS2). Encouragingly, the ternary m-CN/BP/WS2 het...