Chelating agents like ethylenediaminetetraacetic acid (EDTA), diethylenetriaminepentaacetic acid (DTPA), and nitrilotriacetic acid (NTA) find extensive application in the removal of residual substances due to their high stability constants with a wide range of metal ions. They also play a crucial role in nuclear decontamination operations aimed at eliminating metallic radionuclides such as 60Co, 90Sr, and 239Pu. However, improper disposal of chelated radioactive waste can lead to significant increases in radionuclide migration rates from disposal sites. Therefore, it is imperative to comprehend the behavior of chelating agents under varying conditions, including pH, temperature, and metal ion concentrations. In this study, we present the results of a pH-dependent composition analysis of nickel-chelate complexes using UV-Vis spectrophotometry. Nickel (Ni) serves as an ideal metal ion for investigating its interactions with chelating agents due to its solubility over a wide pH range and high stability constants with all three chelating agents mentioned earlier. Initially, UV-Vis spectra of Ni-EDTA, Ni-DTPA, and Ni-NTA complexes were recorded at various pH levels. We assigned absorption maxima and compared our findings with existing literature on each Ni-chelate complex. Furthermore, we examined mixed samples of all three complexes, varying the pH to monitor changes in composition. The results and their implications will be presented in our poster presentation.

Plutonium exhibits a variety of oxidation states and has a strong affinity for complexation with organic ligands. Isosaccharinic acid (ISA) is a major degradation product of cellulose materials present in the low to intermediate radioactive wastes. The interaction between trivalent plutonium and ISA can significantly impact the migration and containment of plutonium in the repository environment. In this study, formation of Pu(III) and ISA complexes was investigated at an ionic strength of 1 M of NaClO4 using UV-Vis absorption spectrophotometry. To exclude the effect of the Pu(III) oxidation, absorption spectra were measured within 10 min after adding ISA into Pu(III) solution and processed using HYPSPEC software for deconvolution after baseline correction. Several previous studies showed that the presence of ligands accelerates the oxidation of Pu(III) to Pu(IV). To investigate whether ISA complexation can also accelerate the Pu(III) oxidation, UV-Vis absorption spectra changes over 24 hours were analyzed as a function of the ratio of ISA to plutonium concentration.

빈카마이너 L.의 알칼로이드는 HPLC의 PDA 검출기를 이용하여 측정하고 이를 표준시료인 빈카민의 자외선/가시광선 흡수 스펙트럼과 비교하여 분석하였다. 플라보노이드류를 포함하여 추출물에서 9개 이상의 화합물에 대한 자외선/가시광선 흡수 스펙트럼을 얻었다. 추출방법에 따라 에탄올 추출물과 열수 추출물을 얻고 이를 DPPH 라디칼 소거법에 의해 항산화 효과를 조사하였다. 그 결과 에탄올 추출 물과 열수 추출물 모두 비교군인 케르세틴과 비타민 C 대비 약 14~15%의 항산화 효과를 보여 추출법에 상관없이 유사한 결과를 보였다.

We measured cobalt content in sorghum (Sorghum bicolor (L.) Moench.) by atomic absorption spectrophotometry: their absorbance and back ground values. These analyses were with AA-680 of Shimadzu. The mode was BGC; wave length, 240.8 ㎚, 240.7 ㎚, 240.6 ㎚, respectively. The recommended wave length is 240.7 ㎚ for Co analysis. It was done through several ratios among 4 factors; mean of absorbance(AM), standard deviation of absorbance (AS), mean of background(BM), standard deviation of background.(BS). The result was t㏊t 240.6 ㎚ was the favourable. And t㏊t of 240.8 ㎚ was better t㏊n t㏊t of 240.7 ㎚ for the Co analysis.

The absolute measurements of fluxes in the region λ λ 3 , 100 − 8 , 090 |AA emitted in the visible continua of some galactic Wolf-Rayet stars are presented. These observations were made by a two-channel scanner which was built up cooperatively by the Observatoire of Lyon and the Laboratoire d'Astronomie Spatiale. The fluxes, dereddened from those data, were combined with IUE and ANS ultraviolet measurements. These fluxes were compared with those of LTE plane paralleled model atmospheres of Kurucz (1979) and were also integrated in order to derive effective temperatures and bolometric corrections for the program stars. The derived effective temperatures and bolometric corrections for the stars were in the range of 25, 000 K ∼ 32,700 K, and of − 2.5 mag . ∼ − 3.7 mag ., respectively.

The effective temperatures and the bolometric corrections of 0-G type stars and derived from de-reddened monochrometric and integrated fluxes obtained by absolute spectrophotometry on the ground and satellite (IUE, 1985, OAO : Code and Meade, 1979 ; Code et al., 1980), using the method simillar to that of Code et al.(1976) with the LTE model atmospheres by Kurucz(1979). The effective temperatures and the bolometric corrections derived from this work are found to be in good agreement with those of Code et al. (1976), Morossi and Malagnini (1985), Malagnini et al. (1985) etc., being significant for basic astrophysical quantities.

Polyelectrolyte titration, which was called colloid titration is based on the stoichiometric reaction between oppositely charged polyelectrolytes. This can be used, for instance, to determine the charge density of a cationic polyelectrolyte, using an anionic polyelectrolyte of known charge density, such as potassium polyvinyl sulfate (PPVS). The technique requires a suitable method of end-point detection and there are several possibilities. In this work, two methods have been investigated: visual titrimetry based on the color change of a cationic dye (o-toluidine blue, o-Tb) and spectrophotometry based on the absorbance change corresponding to the color change of the same dye. These have been applied to several cationic polyelectrolytes with different charge density and molecular weight. In all cases, the cationic charge was due to quaternary nitrogen groups. In the case of cationic dye, it was shown that the sharpness depends on the charge density of cationic polyelectrolyte. With the polyelectrolytes of lower charge density, the binding to PPVS is weaker and binding of the dye to PPVS can occur before all of the polyelectrolyte charge has been neutralized. However, by carrying out titrations at several polyelectrolyte concentrations, good linear relationships were found, from which reliable charge density values could be derived. Effects of pH and ionic strength were also briefly investigated. For cationic polyelectrolytes (copolymers of acrylamide and dimethylaminoethyl acrylate), there was some loss of charge at higher pH values, probably as a result of hydrolysis. Increasing ionic strength causes a less distinct color change of o-Tb, as a result of weaker electrostatic interactions.