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A novel indicator system for catalytic spectrophotometric determination and speciation of inorganic selenium species (Se(Ⅳ), Se(Ⅵ)) at trace levels in natural lake and river water samples

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Rare Metals 2011年第5期30卷 477-487页

作者： Ramazan Gürkan Halil brahim Ulusoy Mehmet Akay pinar bulut Department of Chemistry Faculty of Science University of Cumhuriyet

A novel catalytic kinetic method is proposed for the determination of Se（Ⅳ）, Se（Ⅵ）, and total inorganic selenium in water based on the catalytic effect of Se（Ⅳ） on the reduction of Celestine blue by sodium sulfide at pH 7.0 phosphate buffer. The fixed-time method was adopted for the determination and speciation of inorganic selenium. Under the optimum conditions, the two calibration graphs are linear with a good correlation coefficient in the range 2-20 and 20-200 μg·L-1 of Se（Ⅳ） for the fixed-time method at 30℃. The experimental and theo- retical detection limits of the developed kinetic method were found to be 0.21 and 2.50 μg·L-1 for the fixed-time method （3 min）. All of the variables that affect the sensitivity at 645 nm were investigated, and the optimum conditions were established. The interference effect of various cations and anions on the Se（Ⅳ） determination was also studied. The selectivity of the selenium determination was greatly improved with the use of the strongly cation exchange resin such as Amberlite IR120 plus as long as chelating agents of thiourea and thiosulphate. The proposed kinetic method was validated statistically and through recovery studies in natural water samples. The relative standard deviations （RSDs） for ten replicate measurements of 2, 10, and 20 μg·L-1 of Se（Ⅳ） change between 0.35% and 5.58%, while the RSDs for ten replicate measurements of 3, 6, and 12 μg·L-1 of Se（Ⅵ） change between 0.49% and 1.61%. Analyses of a certified standard reference material （NIST SRM 1643e） for selenium using the fixed-time method showed that the proposed kinetic method has good accuracy. The Se（Ⅳ）, Se（Ⅵ）, and total inorganic selenium in lake and river water samples have been successfully determined by this method after selective reduction of Se（Ⅵ） to Se（Ⅳ）.

关键词： selenium speciation Celestine blue catalytic effect kinetic spectrophotometry natural waters

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What is the relationship between frailty and orthostatic hypotension in older adults?

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Journal of Geriatric Cardiology 2019年第3期16卷 272-279页

作者： Suleyman Emre Kocyigit pinar Soysal Esra Ates bulut Ali Ekrem Aydin Ozge Dokuzlar Ahmet Turan Isik Unit for Aging Brain and Dementia Department of Geriatric MedicineFaculty of MedicineDokuz Eylul UniversityIzmirTurkey Department of Geriatric Medicine Bezmialem Vakif UniversityFaculty of MedicineIstanbulTurkey

Background Frailty and orthostatic hypotension (OH),which is common in older adults,is associated with morbidity and *** relationship between them remains *** aim of the study is to determine whether there is a relationship between frailty and *** A total of 496 patients who were admitted to the geriatric clinic and underwent comprehensive geriatric assessment were retrospectively *** a cross-sectional and observational study,OH was measured by the Head-up Tilt Table test at 1,3,and 5 min (respectively,OH1,OH3,and OH5) and the frailty was measured by the Fried’s frailty *** The mean age of all patients was 75.4 ± *** prevalence of females was 69.8%.When the frail people were compared with the pre-frail and the robust ones,the frailty was associated with *** was no relationship between the groups in terms of OH1 when the pre-frail group was compared with the robust ***3 were higher in the frail group than in the pre-frail group (P 0.05).Slowness and weakness were associated with OH1 (P < 0.05),whereas the other components of the Fried’s test were *** Frailty may be a risk factor for *** 1^st min measurements of OH should be routinely evaluated in frail older adults to prevent OH-related poor outcomes.

关键词： Frail Orthostatic hypotension Pre-frail Robust

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