The discovery of (meta)stable pre-nucleation species (PNS) challenges the established nucleation-and-growth paradigm. While stable PNS with long lifetimes are readily accessible experimentally, identifying and characterizing early-stage intermediates with short lifetimes remains challenging. We demonstrate that species with lifetimes ≪ 5 s can be characterized by nuclear magnetic resonance spectroscopy when boosted by 'Bullet' dynamic nuclear polarization (Bullet-DNP).
View Article and Find Full Text PDFHyperpolarized pyruvate is a widely used marker to track metabolism in vivo and a benchmark molecule for hyperpolarization methods. Here, we show how a combination of improved bullet-DNP instrumentation, an optimized sample preparation and a further sensitivity increase via a C-H polarization transfer after dissolution enable the observation of pyruvate at a concentration of 250 nM immediately after dissolution. At this concentration, the experiment employs a total mass of pyruvate of only 20 ng or 180 pmol.
View Article and Find Full Text PDFStable isotope techniques are precise methods for studying various aspects of hydrology, such as precipitation characteristics. However, understanding the variations in the stable isotope content in precipitation is challenging in Iran due to numerous climatic and geographic factors. To address this, forty-two precipitation sampling stations were selected across Iran to assess the fractional importance of these climatic and geographic parameters influencing stable isotopes.
View Article and Find Full Text PDFIt is shown that proton spins highly polarized by dynamic nuclear polarization (DNP) retain substantial polarization upon the rapid transfer of frozen bullets from a polarizer to an NMR spectrometer. After injection in solution, the resulting hyperpolarization in aliphatic chains comprises population imbalances between singlet and triplet states of geminal protons and combinations thereof. These hyperpolarized long-lived states (LLSs) can be reconverted into observable transverse magnetization by polychromatic spin-lock-induced crossing (poly-SLIC).
View Article and Find Full Text PDFEnviron Sci Pollut Res Int
June 2024
Sea surface temperature (SST), with its complex and dynamic behavior, is a major driver of ocean-atmosphere interactions. The purpose of this study is to investigate the behavior of SST and its prediction using a chaotic approach. Average mutual information (AMI) and Cao methods were used to reconstruct the phase space.
View Article and Find Full Text PDFThe Chao Phraya River Deltaic Plain is the largest basin in Thailand and the second largest one in Southeast Asia after the Mekong River Delta. In recent decades, the groundwater quality in the Lower Chao Phraya River Basin in Thailand has deteriorated due to salinization caused by seawater intrusion. In the present study, hydrogeochemical and statistical methods were employed to determine the hydrochemical characteristics of the groundwater and to investigate the possible sources of salinity in the study region for the years 2008 and 2020.
View Article and Find Full Text PDFThis study determined the main local and regional parameters affecting the stable isotopes (O, H) in the Bangkok precipitation and developed the Bangkok meteoric water line (BMWL) (H = (7.68 ± 0.07) O + (7.
View Article and Find Full Text PDFUnlabelled: Alpine habitats are characterized by a high rate of range restricted species compared to those of lower elevations. This is also the case for the Irano-Anatolian global biodiversity hotspot in South-West Asia, which is a mountainous area harbouring a high amount of endemic species. Using two quantitative approaches, Endemicity Analysis and Network-Clustering, we want to identify areas of concordant species distribution patterns in the alpine zone of this region as well as to test the hypothesis that, given the high proportion of endemics among alpine species, delimitation of these areas is determined mainly by endemic alpine species, i.
View Article and Find Full Text PDFIsotopes Environ Health Stud
August 2021
Iran is a semi-arid and arid country which always faces a water shortage crisis. Thus, the water resources in Iran should be studied by accurate methods such as stable isotope techniques. In precipitation sampling stations across Iran, the O (ranges from -16.
View Article and Find Full Text PDFAsbestos, as with other pollutants in the air, has adverse effects on the health of human beings and animals. Today, the relationship between presence of asbestos fibers in the air breathed by humans and developing serious diseases such as lung cancer (asbestosis) and mesothelioma has been proven. The objectives of this study were to monitor the levels of asbestos fibers in ambient air of Mashhad, Iran during 2018, and to draw its Geographic Information System (GIS) distribution map for the city.
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