Zonguldak Karaelmas University

About: Zonguldak Karaelmas University is a based out in . It is known for research contribution in the topics: Population & Copolymer. The organization has 1939 authors who have published 4296 publications receiving 62466 citations.

Chaotic resonance in Hodgkin–Huxley neuron

Abstract: Chaotic Resonance (CR), whereby the response of a nonlinear system to a weak signal can be enhanced by the assistance of chaotic activities that can be intrinsic or extrinsic, has recently been studied widely. In this paper, the effects of extrinsic chaotic signal on the weak signal detection performance of the Hodgkin–Huxley neuron are examined via numerical simulation. The chaotic signal has been derived from Lorenz system and is injected to neuron as a current. Obtained results have revealed that the H–H neuron exhibits CR phenomenon depending on the chaotic current intensity. Also, we have found an optimal chaotic current intensity ensuring the best detection of the weak signal in H–H neuron via CR. In addition, we have calculated the maximal Lyapunov exponent to determine whether the H–H neuron is in chaotic regime. After determining the state of the neuron, we have shown that the H–H neuron can be able to detect the weak signal even if it is in the chaotic regime. Finally, we have investigated the effects of chaotic activity on the collective behavior of H–H neurons in small-world networks and have concluded that CR effect is a robust phenomenon which can be observed both in single neurons and neuronal networks.

A simple solvent collection technique for a dispersive liquid–liquid microextraction of parabens from aqueous samples using low‐density organic solvent

Abstract: A simple technique for the collection of an extraction solvent lighter than water after dispersive liquid-liquid microextraction combined with high-performance liquid chromatography with ultraviolet detection was developed for the determination of four paraben preservatives in aqueous samples. After the extraction procedure, low-density organic solvent together with some little aqueous phase was separated by using a disposable glass Pasteur pipette. Next, the flow of the aqueous phase was stopped by successive dipping the capillary tip of the pipette into anhydrous Na(2)SO(4). The upper organic layer was then removed simply with a microsyringe and injected into the high-performance liquid chromatography system. Experimental parameters that affect the extraction efficiency were investigated and optimized. Under optimal extraction conditions, the extraction recoveries ranged from 25 to 86%. Good linearity with coefficients with the square of correlation coefficients ranging from 0.9984 to 0.9998 was observed in the concentration range of 0.001-0.5 μg/mL. The relative standard deviations ranged from 4.1 to 9.3% (n = 5) for all compounds. The limits of detection ranged from 0.021 to 0.046 ng/mL. The method was successfully applied for the determination of parabens in tap water and fruit juice samples and good recoveries (61-108%) were achieved for spiked samples.

Can partially hydrolyzed guar gum be an alternative to lactulose in treatment of childhood constipation

Abstract: BACKGROUND/AIMS In the present study, we aimed to investigate if partially hydrolyzed guar gum (PHGG) can be used safely as a fiber source for treatment of constipation in children and to compare its success with the most commonly used osmotic laxative, lactulose. METHODS A randomized prospective controlled study on 61 patients (partially hydrolyzed guar gum group, n: 31; lactulose group, n: 30) was performed. Patients were given lactulose or partially hydrolyzed guar gum for four weeks. Using a standardized bowel diary, defecation frequency, stool consistency, and presence of flatulence and abdominal pain were recorded. Family questionnaires about the success, safety and side effect profile of both treatment arms were also obtained. RESULTS No significant differences were found in the baseline daily fiber (fruits and vegetables) intake between the two groups. Bowel movement frequency per week and stool consistency improved significantly in both treatment groups (p<0.05). The percent of children with abdominal pain and stool withholding also decreased eminently in both groups (p<0.05). Weekly defecation frequency increased from 4±0.7 to 6±1.06 and from 4±0.7 to 5±1.7 in the lactulose and partially hydrolyzed guar gum treated groups, respectively (p<0.05). According to the family questionnaire, the parents complained of bad taste, flatulence and necessity to ingest a high amount of drug in the lactulose treatment group. In the partially hydrolyzed guar gum treatment group, parents were satisfied with the defecation frequency of their children. CONCLUSIONS Treatment with partially hydrolyzed guar gum is as effective as lactulose treatment in relieving stool withholding and constipation-associated abdominal pain, and its use improves stool consistency. Lactulose seemed to have more side effects, including flatulence and sensation of bad taste.

Protective effects of vitamin C, alone or in combination with vitamin A, on endotoxin-induced oxidative renal tissue damage in rats.

Abstract: This study was designed to investigate the protective effects of vitamin C and vitamin A on oxidative renal tissue damage. Male Wistar rats were given an intraperitoneal injection of 0.5 ml saline (control) or 0.5 ml solution of lipopolysaccharide (10 mg/kg), which caused endotoxemia. Immediately (within 5 min) after the endotoxin injection, the endotoxemic rats were untreated or treated with intraperitoneal injection of vitamin A (195 mg/kg bw), vitamin C (500 mg/kg bw) or their combination. After 24 hours, tissue and blood samples were obtained for histopathological and biochemical investigation. Endotoxin injection caused renal tissue damage and increased erythrocyte and tissue malondialdehyde (MDA) and serum nitric oxide (NO), urea and creatinine concentrations, but decreased the superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and catalase (CAT) activities compared to the parameters of control animals. Treatment with vitamin C or with vitamins C and A significantly decreased the MDA levels and serum NO, urea and creatinine levels, recovered the antioxidant enzyme activities (SOD, GSH-Px and CAT), and prevented the renal tissue damage in endotoxemic rats. In contrast, vitamin A alone did not change the altered parameters except for creatinine levels. Notably, the better effects were observed when vitamins A and C given together. It is concluded that vitamin C treatment, alone or its combination with vitamin A, may be beneficial in preventing endotoxin-induced oxidative renal tissue damage and shows potential for clinical use.