MULTIELEMENT ANALYSIS OF LAKE BAIKAL WATER BY HR-ICP-MS

 ABSTRACT Twenty-four elements in Lake Baikal water were determined by HR-ICP-MS instrument, where two river water reference materials, JSAC 0302 and JAC 0032, were applied to verification of the accuracy of analysis. The concentrations of the analyte elements covered a range of nine orders of magnitude, from approximately 17 µg mL-1 of Ca to less than 2 - 3 pg mL-1 of Cs. Lake Baikal water samples from various water depths showed similar chemical compositions to one another.  The distribution of the elements in Lake Baikal water was compared with that in Lake Biwa water, which is the largest lake in Japan. Despite the general similarity in elemental distribution of the two lakes, U and Li were relatively enriched in Lake Baikal water while Y, Mn, and As were relatively enriched in Lake Biwa. Based on the enrichment factor of elements in lake waters, the relative low Li concentration in Lake Biwa water was suggested to be an anomaly, which might be attributed to the deposition of organic deposit that enriched Li. Keywords : multielement analysis, lake water, HR-ICP-MS

AN IN-SYRINGE La CO-PRECIPITATION METHOD FOR PRE-CONCENTRATION OF OXO-ANIONS FORMING ELEMENTS IN SEAWATER FOLLOWED BY ICP-MS MEASUREMENT

Vol. 1 No. 1ABSTRACT A lanthanum (La) co-precipitation method was explored for pre-concentration of oxo-anion forming elements followed by measurement with Inductively Coupled Plasma Mass Spectrometry (ICP-MS).  The co-precipitation and subsequent washing and elution steps were performed in a 25 mL-volume syringe in order to save the sample consumption and to avoid the contamination from the experimental environment.  In the present work, various parameters such as the concentration of La added into the sample solution, the pH, aging time, and so on were optimized to obtain good recoveries and analytical detection limits for V, As, Se, Sb, and W.  Generally, in the co-precipitation method, high concentration of precipitant (in this case, La) causes a serious problem of signal memory effect in ICP-MS measurement. To reduce such memory effect, in the present experiment, high level of La was removed by passing the analyte solution (i.e., lanthanum hydroxide dissolved in 1 M HNO3) through a mini column packed with cation-exchange resins.  The method thus obtained was evaluated through the measurement of V, As, Se, Sb and W in seawater reference materials (CASS-4 and NASS-5). The recoveries exceeded 80%, and the observed values were in good agreement with the certified values. Thus, the present method was applied to the determination of trace elements in real seawater sample.    Keywords: Lanthanum, pre-concentratio

Challenges of Zero-Shot Recognition with Vision-Language Models: Granularity and Correctness

This paper investigates the challenges of applying vision-language models (VLMs) to zero-shot visual recognition tasks in an open-world setting, with a focus on contrastive vision-language models such as CLIP. We first examine the performance of VLMs on concepts of different granularity levels. We propose a way to fairly evaluate the performance discrepancy under two experimental setups and find that VLMs are better at recognizing fine-grained concepts. Furthermore, we find that the similarity scores from VLMs do not strictly reflect the correctness of the textual inputs given visual input. We propose an evaluation protocol to test our hypothesis that the scores can be biased towards more informative descriptions, and the nature of the similarity score between embedding makes it challenging for VLMs to recognize the correctness between similar but wrong descriptions. Our study highlights the challenges of using VLMs in open-world settings and suggests directions for future research to improve their zero-shot capabilities

Effect of ashing temperature on accurate determination of plutonium in soil samples

An acidic leaching method using HNO3 is widely employed to release the global fallout Pu from soil samples for further chemical separations in radioecology and toxicology studies, and in many applications using Pu as a useful tracer. In the method’s sample ash treatment step to decompose organic matter in soil, various ashing temperatures (400 – 900˚C) are used. However, the effect of ashing temperature on the accurate Pu analysis has not been well investigated. In this study, two standard reference soils (IAEA-soil-6 and IAEA-375) were used to determine the ashing temperature effect (from 375 to 600˚C) on HNO3 leaching method. The Pu analytical results of both standard reference materials showed that lower 239+240Pu activity was observed when the ashing temperature exceeded 450˚C, and the 239+240Pu activity continue to decrease as the ashing temperature was raised. Approximately 40% of the Pu content could not be leached out by concentrate HNO3 after ashing for 4 h at 600˚C. The Pu loss was attributed to the formation of refractory materials, which are insoluble in HNO3 solution. This hypothesis was confirmed by the XRD analysis of soil samples which revealed that plagioclase-like silicate materials were formed after high temperature ashing. To ensure the Pu release efficiency in HNO3 leaching, we recommend 450˚C as the ideal ashing temperature. This recommendation is also useful for analysis of other important artificial radionuclides (e.g. 137Cs, 90Sr, 241Am) for which an ashing process is needed to decompose the organic content in soil samples

Search for Narrow Resonances Decaying to Dijets in Proton-Proton Collisions at √s = 13 TeV

A search for narrow resonances in proton-proton collisions at √s = 13  TeV is presented. The invariant mass distribution of the two leading jets is measured with the CMS detector using a data set corresponding to an integrated luminosity of 2.4  fb^(−1). The highest observed dijet mass is 6.1 TeV. The distribution is smooth and no evidence for resonant particles is observed. Upper limits at 95% confidence level are set on the production cross section for narrow resonances with masses above 1.5 TeV. When interpreted in the context of specific models, the limits exclude string resonances with masses below 7.0 TeV, scalar diquarks below 6.0 TeV, axigluons and colorons below 5.1 TeV, excited quarks below 5.0 TeV, color-octet scalars below 3.1 TeV, and W′ bosons below 2.6 TeV. These results significantly extend previously published limits

Ultralight vector dark matter search using data from the KAGRA O3GK run

Among the various candidates for dark matter (DM), ultralight vector DM can be probed by laser interferometric gravitational wave detectors through the measurement of oscillating length changes in the arm cavities. In this context, KAGRA has a unique feature due to differing compositions of its mirrors, enhancing the signal of vector DM in the length change in the auxiliary channels. Here we present the result of a search for U(1)B−L gauge boson DM using the KAGRA data from auxiliary length channels during the first joint observation run together with GEO600. By applying our search pipeline, which takes into account the stochastic nature of ultralight DM, upper bounds on the coupling strength between the U(1)B−L gauge boson and ordinary matter are obtained for a range of DM masses. While our constraints are less stringent than those derived from previous experiments, this study demonstrates the applicability of our method to the lower-mass vector DM search, which is made difficult in this measurement by the short observation time compared to the auto-correlation time scale of DM