Alternative material recommendation for facade cladding: High silica-containing stonepaste ceramics.

This study investigated the potential of using stonepaste ceramics, which were widely preferred as a coating and decoration material on the facades of architectural buildings in ancient times and continues to be produced on a workshop scale today as a cladding material on building facades. Stonepaste ceramics, made from a mixture prepared with a high amount of crystalline quartz as well as frit, plastic clay, and bentonite raw materials, were hand-shaped and sintered at 930 °C after glazing. The physico-mechanical properties of stonepaste ceramics, their behaviour under various environmental conditions (resistance to chemicals, frost, and thermal shock), and their microstructures have been characterized. The characterization results were compared with the properties of commonly used facade cladding materials. It was determined that stonepaste ceramics had a very low firing shrinkage value (2.84 %) compared to that of other ceramic cladding materials, a higher water absorption value (11.79 %) than that of porcelain tiles and floor tiles, and close to wall tiles, and a flexural strength value (33.64MPa) higher than wall tiles and close to porcelain tiles despite the high-water absorption value. Ten cycles of thermal shock resistance showed that the body and glaze layer of the stonepaste ceramic material are well bonded to each other, and there is no significant thermal expansion mismatch between them. One hundred cycles of freeze-thaw conditions indicated that the stonepaste ceramic had good adhesion and thermal expansion compatibility between the glaze and the body but only chipping damage under the action of tensile forces caused by the freezing of water entering the pores of the body. In terms of behaviour against various chemicals, stonepaste ceramics were found to be highly resistant to high and low concentrations of household chemicals, swimming pool salts, and alkalis but less resistant to low concentrations of HCl and citric acid and high concentrations of HCl and lactic acid compared to other chemicals. The results show that stonepaste ceramics, despite their high-water absorption potential, have properties close to those of traditional ceramic tiles and, like these materials, can serve for significant periods in various environmental conditions when used as facade cladding. Consequently, it has been revealed that stonepaste ceramics can be used as a facade cladding material in sustainable, long-lasting, contemporary architectural facades thanks to their technical and protective properties.

A comparative study of superoxide dismutase, catalase, and glutathione peroxidase activities and nitrate levels in vitiligo patients.

BACKGROUND: Several groups have shown the involvement of oxidative stress in the pathophysiology of vitiligo. METHODS: In this study, we examined the erythrocyte and plasma activities of glutathione peroxidase and Cu/Zn superoxide dismutase, plasma nitrite/nitrate levels, and erythrocyte catalase activity in 23 vitiligo patients and 25 controls. RESULTS: The results show that erythrocyte superoxide dismutase activity and plasma nitrite/nitrate levels are high in vitiligo patients. CONCLUSIONS: Our study confirms that oxidative stress is involved in the pathophysiology of vitiligo, as indicated by the high levels of erythrocyte superoxide dismutase activity and plasma nitrite/nitrate.

Effect of combined treatment with melatonin and methylprednisolone on neurological recovery after experimental spinal cord injury.

Spinal cord injury (SCI) results in the loss of function below the lesion. Secondary injury following the primary impact includes a number of biochemical and cellular alterations leading to tissue necrosis and cell death. Methylprednisolone (MP), by reducing edema and protecting the cell membrane against peroxidation, is the only pharmacological agent with a proven clinically beneficial effect on SCI. Melatonin, known as a free radical scavenger, has been shown to have an effect on lipid peroxidation following experimental SCI. The purpose of this study was to examine the effect of MP and melatonin on neurological, ultrastructural, and electrophysiological recovery. Female albino rats weighing 200-250 g were randomized into five groups of 18 rats each and six rats for the control group. Weight-drop trauma was performed for each group and a 30-mg/kg single dose of MP for rats in group 1, a 10-mg/kg single dose of melatonin for rats in group 2, and MP and melatonin in the same doses for rats in group 3 were administered immediately after trauma. The rats in group 4 were the vehicle group (treated with ethanol) and group 5 was the trauma group. The motor and somatosensory evoked potentials were recorded at the 4th hour, the 24th hour, and on the 10th day of the study for six rats in each group. Posttraumatic neurological recovery was recorded for 10 days using "motor function score" and inclined plane test. After electrophysiological study the rats were terminated for an analysis of lipid peroxidation level of the injured site of the spinal cord. Electron microscopic studies were performed to determine the effects of melatonin, MP, and the combined treatment with MP and melatonin on axons, neurons, myelin, nucleus, and intracytoplasmic edema. The groups treated with MP, melatonin, and a combination of both had significantly enhanced electrophysiological, biochemical, and neurological recovery and also showed better ultrastructural findings than the trauma and vehicle groups. Although combined treatment was significantly more effective on lipid peroxidation than melatonin or MP treatments alone, at the 10th day, neurobehavioral, electrophysiological, and ultrastructural recovery were at the same level. In conclusion, MP, melatonin, and MP and melatonin combined treatment modalities improved functional recovery at the same level. Future studies involving different doses of melatonin and different dose combinations with MP could promise better results since each drug has a different anti-oxidative mechanism of action.

Exploration of the early auditory effects of hyperlipoproteinemia and diabetes mellitus using otoacoustic emissions.

Although the relationship between hearing loss and hyperlipoproteinemia (HLP) or diabetes mellitus (DM) has been shown in many clinical investigations, this concept is still controversial. A prospective study was designed to search for the existence of subclinical auditory dysfunction related to HLP and DM by transient-evoked (TEOAEs) and distortion-product otoacoustic emissions (DPOAEs) in patients with hearing levels better than 30 dB. Evoked otoacoustic emissions were utilized to investigate subclinical auditory dysfunction. Fifteen hypercholesterolemic patients (28 ears), 21 hypertriglyceridemic patients (42 ears) and 21 DM patients (40 ears) were eligible for investigation. The results of the DPOAEs and TEOAEs of the study groups were compared with the control group composed of individuals with similar ages and with normal blood lipids and glycemia. This group consisted of 22 people (44 ears). There was no difference in the existence of TEOAEs at all frequencies among the groups (P>0.05). No differences were found in the amplitudes of the DPOAES between the groups except at 4 kHz (P>0.05). The difference was caused by the hypertriglyceridemia group (P=0.014) and the non-insulin-dependent diabetes mellitus (NIDDM) group (P=0.012) when compared with the control group. The mean DPOAE amplitudes of the hypertriglyceridemic and NIDDM groups at 4 kHz were higher than those of the control group. The decreased DPOAE amplitudes at 4 kHz in hypertriglyceridemic and diabetic patients without clinical findings are compatible with the sensorineural hearing loss observed with hyperviscosity and increased noise susceptibility, as was shown before in these patients. Longitudinal investigations should be performed with otoacoustic emissions to help with the early prediction of the prospective effects of HLP and DM on the auditory system.

Comparison of the selenium level with GSH-Px activity in the liver of mice treated with 7,12 DMBA.

In this study, the relationship between selenium (Se) and glutathione peroxidase (GSHPx) levels was investigated in 7,12-dimethylbenz(a)anthracene (7,12-DMBA)-treated mouse liver. The potential mammary carcinogen 7,12-DMBA, was injected intraperitoneally (20 mg kg(-1) day(-1)) into 10-12 month old female mice. After 21 days of application the mice were sacrificed and GSHPx and Se levels of liver homogenates were measured. Se and GSHPx levels in 7,12-DMBA-treated mice were significantly lower than those of controls (p < 0.05). The control group exhibited 0.9 +/- 0.066 U mg(-1) protein and 0.86 +/- 0.058 p.p.m. levels of GSHPx and Se respectively. The 7,12-DMBA-treated group had significantly (p < 0.05) decreased GSHPx and Se levels (0.42 +/- 0.062 U mg(-1) protein and 0.69 +/- 0.034 p.p.m. respectively). The results show a direct relationship between Se and GSHPx activity and a negative correlation between antioxidant capacity and existence of a carcinogen in metabolism.