Purpose
This study aims to produce homogenously prepared polymer composites by adding two different strontium aluminate derivatives (Sr4Al14O25 and SrAl2O4) to urea-formaldehyde (UF) at different ...mass concentrations. In the context of this work those strontium-based derivatives were compared in terms of mechanical and luminescent characteristics. Additionally, sodium bicarbonate was integrated with the prepared composites to eliminate/minimize darkening problem, which might arise from the oxidation of Eu +2 to Eu2O3, on the surface of strontium aluminate/urea-formaldehyde composites.
Design/methodology/approach
In this study, strontium aluminate/UF composite materials were produced using a compression molding technique. Their mechanical, thermomechanical and luminescence properties were investigated via various characterization methods. Particle size analysis was used to characterize phosphor derivatives, whereas scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX) was conducted for morphological examination.
Findings
The darkening problem was prevented by the introduction of sodium bicarbonate into the composite systems. Based on the characterization and test results, the only addition of strontium aluminate reduced the mechanical properties. However, it was seen that the introduction of sodium bicarbonate into the composites improved those properties positively. The appropriate amounts of strontium aluminate and sodium bicarbonate were determined by conducting an experimental optimization study. The optimum composition of the composite materials was obtained by introducing 2% phosphor and 3% NaHCO3.
Originality/value
The approach used in this study has provided a method to solve the darkening problem, which degrades the aesthetic appearance in industrial production.
Experimental studies in the aqueous solution are crucial for the detection of metal cations in environmental and biological media. Polymer materials allow to work in aqueous media for fluorescent ...substances which are insoluble in water. Fluorescence sensor studies of the phenanthroimidazole imine compound (PI) synthesized previously by our group were performed in the polymer medium and the selective response to Fe (III) cation was obtained. The resulting sensor exhibited a selective fluorescence quenching effect to Fe (III). A logarithmic calibration graph was obtained in the range of 5.0 × 10
− 5
and 1.0 × 10
− 2
M. The interference effects of other ions besides Fe (III) have been examined and it has been observed that PI compound behaves selectively to Fe (III) ion in aqueous media. In addition, regeneration and reproducibility studies were carried out to determine the long-term usage of PI doped polymer film and reproducible results have been obtained for Fe (III) cation.
The phenanthroimidazole derivatives are used in the drug industry in large scale. In this study four new phenanthroimidazole-imine derivatives were synthesized and their spectroscopic studies as well ...as their antioxidant behaviors were examined. Structural analyses were made by FT-IR,
1
H-NMR,
13
C-NMR, LC-MS spectroscopy techniques. UV–vis absorption and emission spectroscopy techniques have been used to determine the photophysical characteristics of four newly synthesized phenanthroimidazoles. The maximum absorption and emission wavelengths, molar extinction coefficients (ε), singlet energy levels (Es), Stokes’ shift values (Δλ) of phenanthroimidazole-imine derivatives are given. Additionally, the antioxidant behavior of all compounds were investigated which the ascorbic acid used as standard molecule in present study.
The aim of this study is the investigation of the interaction between dyes and polymers which have different polarities. Dye doped polymer films have larger application areas because of the fact that ...dye is more stable when doped in polymer compared to solvent medium. However, dye dispersion in the polymer medium affects both the spectroscopic and mechanical properties of the polymer. The polymer-dye interaction must be high for a good dispersion,. In this study, polypropylene with apolar character and polymethylmethacrylate with polar groups were chosen as a solid phase to examine polymer-dye interactions. The photophysical properties of phenanthroimidazole-azo compounds synthesized previously were examined with UV-visible and fluorescence spectroscopy techniques in tetrahydrofuran and two polymer media. Also, photostability tests of azo dyes in THF and polymer films were performed. Surface roughness characterizations of polymer films were carried out with AFM. Additionally, the viscoelastic behaviors of the polymethylmethacrylate and polypropylene films under sinusoidal vibrations at different temperatures were studied by dynamic mechanical analysis technique.
Objective: It has been shown that pain, depression, and fatigue related to Obstructive Sleep Apnea syndrome (OSAS) results in a significant socioeconomic burden. We aimed to determine the prevalence, ...demographic, and clinical properties of pain symptoms in OSAS patients. Materials and Methods: We evaluated 84 OSAS patients diagnosed after full-night polysomnography with the Brief Pain Inventory, Beck Depression Rating scale (BDS), Pittsburg Sleep Quality index (PSQI), Epworth Sleepiness scale (ESS), Fatigue Impact scale (FIS), and Fatigue Severity scale (FSS). Results: A total of 84 patients (62 males, 22 females) with a mean age of 54.37±11.03 years were included. Headache in 25 (43.1%), myofascial pain in 22 (37.9%), and other types of pain in 11 patients were defined. ESS, FSS, FIS total, physical, cognitive, and psychosocial scores were found to be significantly higher in patients with pain. The presence of pain did not differ according to the severity of OSAS, and no significant difference was found in any parameters between mild, moderate, and severe OSAS except for minimal O2 saturation. A positive correlation between last week pain severity and BDS scores, a negative correlation between PSQI scores and the decrease in pain rate as a result of the treatment, and a weak positive correlation between FIS-cognitive sub-score and pain intensity scores were found. Conclusion: In our study, excessive daytime sleepiness and the impact and severity of fatigue were found to be higher in patients with pain than in those without pain. The most obvious difference was seen in terms of cognitive, and psychosocial fatigue. Contrary to expectations, it was observed that OSAS severity did not affect pain according to our data.
In this study, three
novel phenanthroimidazole derivatives containing azo group were synthesized and
their photophysical properties were investigated. For this purpose,
...2-(4-nitrophenyl)1H-phenanthro9,10-dimidazole structure obtained from 9,10-phenanthroquinone and 4-nitrobenzaldehyde was
reduced with palladium on activated charcoal 10 % and hydrazine hydrate. Phenanthro9,10-dimidazole-2-yl)aniline obtained in
this way was converted to phenantroimidazole-azo derivatives containing
different aromatic groups. Structural analyses were performed by FT-IR, NMR,
LC-MS spectroscopic techniques. Spectral characterizations and photostability
studies of phenanthroimidazole derivatives were performed by UV-vis and
fluorescence spectroscopy in solvent media. The maximum absorption and emission wavelengths, molar
extinction coefficients, singlet energy levels, Stokes’ shift values of
phenanthroimidazole-azo derivatives were obtained.
Abstract Context The paucity of data on microvascular complications in patients with posttransplant diabetes (PTDM) is an obstacle to developing follow-up algorithms. Objective To evaluate diabetic ...microvascular complications in patients with long-standing PTDM. Methods In patients with ≥5-year history of PTDM and age-matched renal transplant recipients without PTDM (NDM), diabetic peripheral neuropathy was evaluated using the Michigan Neuropathy Screening Instrument, the CASE IV device, and in vivo corneal confocal microscopy (CCM). Cardiac autonomic neuropathy tests were performed using heart rate variability. Nephropathy screening was assessed using spot urine albumin/creatinine ratio and eGFR calculation. Diabetic retinopathy was evaluated by fundus examination and photography, and optical coherence tomography. Results This study included 41 patients with PTDM and 45 NDM patients. The median follow-up was 107.5 months in the PTDM group. Peripheral neuropathy was significantly higher in the PTDM group than in the NDM group (P = .02). In the PTDM patients with peripheral neuropathy, corneal nerve fiber density examined by CCM was significantly lower than in PTDM patients without neuropathy (P = .001). Parasympathetic involvement was observed in 58.5% of the PTDM group and 22% of the NDM group (P = .001). Sympathetic involvement was present in 65.9% of the PTDM group and 29.3% of the NDM group (P = .001). Retinopathy was observed in 19.5% of patients in the PTDM group and in none of the NDM patients (P < .001). Renal functions were similar between the study groups. Conclusion Cardiac autonomic neuropathy and diabetic retinopathy can affect patients with PTDM at a high rate. Diabetic retinopathy is a threat to the vision of PTDM patients. Diabetic peripheral neuropathy can be detected early in PTDM patients by CCM.
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