Yakup KOÇ | Toros University, Mersin, Turkey (original) (raw)

Papers by Yakup KOÇ

Renewable Energy, 2009

Alcohols have been used as a fuel for engines since 19th century. Among the various alcohols, eth... more Alcohols have been used as a fuel for engines since 19th century. Among the various alcohols, ethanol is known as the most suited renewable, bio-based and ecofriendly fuel for spark-ignition (SI) engines. The most attractive properties of ethanol as an SI engine fuel are that it can be produced from renewable energy sources such as sugar, cane, cassava, many types of waste biomass materials, corn and barley. In addition, ethanol has higher evaporation heat, octane number and flammability temperature therefore it has positive influence on engine performance and reduces exhaust emissions. In this study, the effects of unleaded gasoline (E0) and unleaded gasoline-ethanol blends (E50 and E85) on engine performance and pollutant emissions were investigated experimentally in a single cylinder four-stroke spark-ignition engine at two compression ratios (10:1 and 11:1). The engine speed was changed from 1500 to 5000 rpm at wide open throttle (WOT). The results of the engine test showed that ethanol addition to unleaded gasoline increase the engine torque, power and fuel consumption and reduce carbon monoxide (CO), nitrogen oxides (NO x ) and hydrocarbon (HC) emissions. It was also found that ethanol-gasoline blends allow increasing compression ratio (CR) without knock occurrence.

European Journal of Pharmacology, 2006

The purpose of this study was to investigate the actions of lamotrigine and levetiracetam on the ... more The purpose of this study was to investigate the actions of lamotrigine and levetiracetam on the conduction properties of isolated rat sciatic nerves in-vitro. Compound action potentials from rat sciatic nerves were recorded using a sucrose-gap technique with single and repetitive stimulation. Lamotrigine, at 0.01 to 1 mM, reduced the amplitude of compound action potentials (3.9 ± 0.6% to 47.9 ± 2.4%) and produced at high frequency dependent (phasic) and independent (tonic) conduction block. Lamotrigine extended the peak time of the compound action potentials significantly without changing the half falling-time (P b 0.05). Lamotrigine reduced the amplitude of the delayed depolarization, which was more pronounced than that of the amplitude of the compound action potentials in the presence of 4-aminopyridine. With tonic and phasic stimulation, 0.1 to 10 mM of levetiracetam did not alter the amplitude, peak time and half falling time of the compound action potentials. In addition, levetiracetam did not change the amplitude of the delayed depolarization and the area of the compound action potentials following application of 4-aminopyridine. These results indicate that lamotrigine produces a powerful tonic block with delayed depolarization, whereas it produces a weaker phasic block in rat sciatic nerve. Levetiracetam has no effect on peripheral nerve conduction even at high concentrations. These results may have the relevance to our understanding of the peripheral effects of lamotrigine and levetiracetam.

International Journal of Neuroscience, 2006

Friedreich&am... more Friedreich's ataxia (FRDA), the most common subtype of early onset hereditary spinocerebellar ataxia (SCA), is an autosomal recessive neurodegenerative disorder caused by unstable GAA tri-nucleotide expansions in the first intron of FRDA gene located at 9q13-q21.1 position. Results of GAA repeat polymorphism in 80 Turkish SCA patients and 38 family members of 11 typical FRDA patients were reported. GAA triplet repeat size ranged from approximately 7 to 34 in normal alleles and from approximately 66 to 1300 in mutant alleles. Twenty six patients were homozygous for GAA expansion and size of expanded alleles differed from approximately 425 to 1300 repeats. Children 2 and 6 years old (showing no ataxia symptoms) of one family had homozygous GAA expansions reaching approximately 925 repeats. All 11 families studied had at least 1 afflicted child and 9 parents and 2 siblings were carrier (heterozygous) with mutant alleles ranging from 66 to 850 repeats. Family studies confirmed the meiotic instability and stronger effect of expansion in the smaller alleles on phenotype and a negative correlation between GAA repeat expansion size and onset-age of the disease.

International Heart Journal, 2005

Friedreich's ataxia (FRDA), the most common subtype of early onset hereditary ataxia, is an autos... more Friedreich's ataxia (FRDA), the most common subtype of early onset hereditary ataxia, is an autosomal recessive neurodegenerative disorder caused by unstable GAA expansions. Two-dimensional, pulse, and pulse tissue Doppler echocardiographic examinations were performed on 21 patients with GAA expansion.

Neurosurgery Quarterly, 2004

ABSTRACT A 22-year-old woman who had headache and numbness on the right side of the face, arm, an... more ABSTRACT A 22-year-old woman who had headache and numbness on the right side of the face, arm, and leg (transient ischemic attack-like) was admitted to the clinic. She had given birth by epidural anesthesia 8 days previously. A subdural hematoma was detected by means of neuroimaging. Spontaneous remission was followed up clinically and radiologically. The complications of epidural anesthesia were discussed, and the awareness of clinicians regarding this matter is pointed out. Subdural hematoma (SDH) was caused by rupture of the bridging veins that go from the cortical surface to the dura mater. The most common causes are anticoagulant use, hemorrhagic diatheses, hypertension, alcoholism, infections (eg, meningitis, tuberculosis), neoplasms, vasculopathies, arteriovenous malformations, aneurysms, hypovitaminosis (especially vitamin C deficiency), and head traumas; however, it occurs rarely after epidural anesthesia (EA). A case with unilateral SDH after EA is presented.

Renewable Energy, 2009

Alcohols have been used as a fuel for engines since 19th century. Among the various alcohols, eth... more Alcohols have been used as a fuel for engines since 19th century. Among the various alcohols, ethanol is known as the most suited renewable, bio-based and ecofriendly fuel for spark-ignition (SI) engines. The most attractive properties of ethanol as an SI engine fuel are that it can be produced from renewable energy sources such as sugar, cane, cassava, many types of waste biomass materials, corn and barley. In addition, ethanol has higher evaporation heat, octane number and flammability temperature therefore it has positive influence on engine performance and reduces exhaust emissions. In this study, the effects of unleaded gasoline (E0) and unleaded gasoline-ethanol blends (E50 and E85) on engine performance and pollutant emissions were investigated experimentally in a single cylinder four-stroke spark-ignition engine at two compression ratios (10:1 and 11:1). The engine speed was changed from 1500 to 5000 rpm at wide open throttle (WOT). The results of the engine test showed that ethanol addition to unleaded gasoline increase the engine torque, power and fuel consumption and reduce carbon monoxide (CO), nitrogen oxides (NO x ) and hydrocarbon (HC) emissions. It was also found that ethanol-gasoline blends allow increasing compression ratio (CR) without knock occurrence.

European Journal of Pharmacology, 2006

The purpose of this study was to investigate the actions of lamotrigine and levetiracetam on the ... more The purpose of this study was to investigate the actions of lamotrigine and levetiracetam on the conduction properties of isolated rat sciatic nerves in-vitro. Compound action potentials from rat sciatic nerves were recorded using a sucrose-gap technique with single and repetitive stimulation. Lamotrigine, at 0.01 to 1 mM, reduced the amplitude of compound action potentials (3.9 ± 0.6% to 47.9 ± 2.4%) and produced at high frequency dependent (phasic) and independent (tonic) conduction block. Lamotrigine extended the peak time of the compound action potentials significantly without changing the half falling-time (P b 0.05). Lamotrigine reduced the amplitude of the delayed depolarization, which was more pronounced than that of the amplitude of the compound action potentials in the presence of 4-aminopyridine. With tonic and phasic stimulation, 0.1 to 10 mM of levetiracetam did not alter the amplitude, peak time and half falling time of the compound action potentials. In addition, levetiracetam did not change the amplitude of the delayed depolarization and the area of the compound action potentials following application of 4-aminopyridine. These results indicate that lamotrigine produces a powerful tonic block with delayed depolarization, whereas it produces a weaker phasic block in rat sciatic nerve. Levetiracetam has no effect on peripheral nerve conduction even at high concentrations. These results may have the relevance to our understanding of the peripheral effects of lamotrigine and levetiracetam.

International Journal of Neuroscience, 2006

Friedreich&am... more Friedreich's ataxia (FRDA), the most common subtype of early onset hereditary spinocerebellar ataxia (SCA), is an autosomal recessive neurodegenerative disorder caused by unstable GAA tri-nucleotide expansions in the first intron of FRDA gene located at 9q13-q21.1 position. Results of GAA repeat polymorphism in 80 Turkish SCA patients and 38 family members of 11 typical FRDA patients were reported. GAA triplet repeat size ranged from approximately 7 to 34 in normal alleles and from approximately 66 to 1300 in mutant alleles. Twenty six patients were homozygous for GAA expansion and size of expanded alleles differed from approximately 425 to 1300 repeats. Children 2 and 6 years old (showing no ataxia symptoms) of one family had homozygous GAA expansions reaching approximately 925 repeats. All 11 families studied had at least 1 afflicted child and 9 parents and 2 siblings were carrier (heterozygous) with mutant alleles ranging from 66 to 850 repeats. Family studies confirmed the meiotic instability and stronger effect of expansion in the smaller alleles on phenotype and a negative correlation between GAA repeat expansion size and onset-age of the disease.

International Heart Journal, 2005

Friedreich's ataxia (FRDA), the most common subtype of early onset hereditary ataxia, is an autos... more Friedreich's ataxia (FRDA), the most common subtype of early onset hereditary ataxia, is an autosomal recessive neurodegenerative disorder caused by unstable GAA expansions. Two-dimensional, pulse, and pulse tissue Doppler echocardiographic examinations were performed on 21 patients with GAA expansion.

Neurosurgery Quarterly, 2004

ABSTRACT A 22-year-old woman who had headache and numbness on the right side of the face, arm, an... more ABSTRACT A 22-year-old woman who had headache and numbness on the right side of the face, arm, and leg (transient ischemic attack-like) was admitted to the clinic. She had given birth by epidural anesthesia 8 days previously. A subdural hematoma was detected by means of neuroimaging. Spontaneous remission was followed up clinically and radiologically. The complications of epidural anesthesia were discussed, and the awareness of clinicians regarding this matter is pointed out. Subdural hematoma (SDH) was caused by rupture of the bridging veins that go from the cortical surface to the dura mater. The most common causes are anticoagulant use, hemorrhagic diatheses, hypertension, alcoholism, infections (eg, meningitis, tuberculosis), neoplasms, vasculopathies, arteriovenous malformations, aneurysms, hypovitaminosis (especially vitamin C deficiency), and head traumas; however, it occurs rarely after epidural anesthesia (EA). A case with unilateral SDH after EA is presented.