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Organometallics Feb 2024Room temperature reaction of elemental cesium with the dimeric lithium chloroberyllate [{SiN}BeClLi] [{SiN} = {CHSiMeN(Dipp)}, where Dipp = 2,6-di-isopropylphenyl, in CD...
Room temperature reaction of elemental cesium with the dimeric lithium chloroberyllate [{SiN}BeClLi] [{SiN} = {CHSiMeN(Dipp)}, where Dipp = 2,6-di-isopropylphenyl, in CD results in activation of the arene solvent. Although, in contrast to earlier observations of lithium and sodium metal reduction, the generation of a mooted cesium phenylberyllate could not be confirmed, this process corroborates a previous hypothesis that such beryllium-centered solvent activation also necessitates the formation of hydridoberyllium species. These observations are further borne out by the study of an analogous reaction performed in toluene, in which case the proposed generation of formally low oxidation state beryllium radical anion intermediates induces activation of a toluene C-H bond and the isolation of the polymeric cesium benzylberyllate, [Cs({SiN}BeCHCH)].
PubMed: 38362487
DOI: 10.1021/acs.organomet.3c00519 -
The Science of the Total Environment Apr 2024Fundamental approaches to the study of groundwater rely on investigating the spatial and temporal distribution of stable and radioactive isotopes and other anthropogenic... (Review)
Review
Fundamental approaches to the study of groundwater rely on investigating the spatial and temporal distribution of stable and radioactive isotopes and other anthropogenic compounds in natural waterbodies. The most often used tracers for estimating groundwater flow paths and residence times, groundwater/surface water interaction as well as tracing chemical (contamination) sources include stable isotopes of water (δ O and δ H), radiocarbon (C; t = 5730 a), tritium (H; t = 12.43 a) as well as unreactive fluorine-containing gases (e.g., chlorofluorocarbons CClF or CFC-11; CClF or CFC-12; CClF or CFC-113; and SF). While gas tracers are usually referred to as transient tracers and are appropriate for investigating modern flow systems, the isotopic tracers are often used to investigated paleo or regional flow systems. Stable isotopes of water can also be used to investigate groundwater/surface water interactions. Another, thus far been less frequently used group of groundwater tracers, are cosmo- and geo- genic short-lived radioisotopes. These isotopes are uniquely suited for studying a wide range of groundwater problems that have short time scales including high aquifer vulnerability to quantitative and qualitative impacts and groundwater discharge to surface waters. Here, we discuss and compare the applications of radio‑sulphur (S; half-life t = 87 d), radio‑beryllium (Be; t = 53 d), radio‑phosphorus (P; combined t = 33 d), natural tritium (H; t = 12.43 a), radon (Rn; t = 3.8 d) and short-lived radium (Ra; combined t = 5.2 d). The paper discusses the principles of the individual tracer methods, focusing on the isotopes' input functions or values, on sampling techniques, and on methods of analyses. Case studies that applied a combined use of the tracers are referred to for readers who wish to learn more about the application of the so far underused cosmo- and geo- genic radioisotopes as aquatic tracers.
PubMed: 38342445
DOI: 10.1016/j.scitotenv.2024.170800 -
Applied Radiation and Isotopes :... Apr 2024The n-lab is a fast neutron facility based in the Department of Physics, University of Cape Town, offering collimated neutron beams produced by an MP 320...
The n-lab is a fast neutron facility based in the Department of Physics, University of Cape Town, offering collimated neutron beams produced by an MP 320 deuterium-tritium sealed tube neutron generator, and a 220 GBq americium-beryllium radioisotopic source. Characterisations of the spatial and energy distributions of the fast neutron beams were performed using an EJ-301 organic liquid scintillator detector and digital data acquisition system. Neutron energy spectra were obtained through unfolding analyses with MAXED, and a Monte Carlo approach to the propagation of uncertainties was implemented. Measurements of fluence and neutron emission rates were determined through the neutron activation of copper foils and subsequently used to validate the scaling of the unfolded neutron energy spectra.
PubMed: 38309120
DOI: 10.1016/j.apradiso.2024.111196 -
Journal of Oral and Maxillofacial... 2023Schaumann bodies are the inclusion bodies usually seen in sarcoidosis, but can also be found in other conditions like tuberculosis, chronic beryllium diseases and...
Schaumann bodies are the inclusion bodies usually seen in sarcoidosis, but can also be found in other conditions like tuberculosis, chronic beryllium diseases and Crohn's diseases. Histopathologically, these bodies appear as round to oval shell-like basophilic calcifications usually considered to be as a residuum of lysosomal organelles activity.
PubMed: 38304499
DOI: 10.4103/jomfp.jomfp_428_23 -
RSC Advances Jan 2024Employing a combination of Density Functional Theory (DFT) calculations and Molecular Dynamics (MD) simulations, the adsorption of molecular hydrogen (H) on...
Employing a combination of Density Functional Theory (DFT) calculations and Molecular Dynamics (MD) simulations, the adsorption of molecular hydrogen (H) on BeAl(SiO)-beryl, a prominent silicate mineral, has been studied. The crystal structure of beryl, which consists of interconnected tetrahedral and octahedral sites, provides a fascinating framework for comprehending H adsorption behavior. Initial investigation of the interaction between H molecules and the beryl surface employed DFT calculations. We identified favorable adsorption sites and gained insight into the binding mechanism through extensive structural optimizations and energy calculations. H molecules preferentially adsorb on the exposed oxygen atoms surrounding the octahedral sites, producing weak van der Waals interactions with the beryl surface, according to our findings. To further investigate the dynamic aspects of H adsorption, MD simulations employing a suitable force field were conducted. To precisely represent interatomic interactions within the BeAl(SiO)-beryl-H system, the force field parameters were meticulously parameterized. By subjecting the system to a variety of temperatures, we were able to obtain valuable information about the stability, diffusion, and desorption kinetics of H molecules within the beryl structure. The comprehensive understanding of the H adsorption phenomenon on BeAl(SiO)-beryl is provided by the combined DFT and MD investigations. The results elucidate the mechanisms underlying H binding, highlighting the role of surface oxygen atoms and the effect of temperature on H dynamics. This research contributes to a fundamental understanding of hydrogen storage and release in beryllium-based silicates and provides valuable guidance for the design and optimization of materials for hydrogen storage, catalysis, gas separation, sensing and environmental applications.
PubMed: 38274172
DOI: 10.1039/d3ra07480c -
Molecules (Basel, Switzerland) Dec 2023Laser ablated Be atoms have been reacted with acetonitrile molecules in 4 K solid neon matrix. The diberyllium products BeBeNCCH and CNBeBeCH have been identified by D...
Laser ablated Be atoms have been reacted with acetonitrile molecules in 4 K solid neon matrix. The diberyllium products BeBeNCCH and CNBeBeCH have been identified by D and C isotopic substitutions and quantum chemical calculations. The stabilization of the diberyllium species is rationalized from the formation of the real Be-Be single bonds with bond distances as 2.077 and 2.058 Å and binding energies as -27.1 and -77.2 kcal/mol calculated at CCSD (T)/aug-cc-pVTZ level of theory for BeBeNCCH and CNBeBeCH, respectively. EDA-NOCV analysis described the interaction between Be and NC···CH fragments as Lewis "acid-base" interactions. In the complexes, the Be moiety carries positive charges which transfer from antibonding orbital of Be to the bonding fragments significantly strengthen the Be-Be bonds that are corroborated by AIM, LOL and NBO analyses. In addition, mono beryllium products BeNCCH, CNBeCH, HBeCHCN and HBeNCCH have also been observed in our experiments.
PubMed: 38202759
DOI: 10.3390/molecules29010177 -
Nanomaterials (Basel, Switzerland) Dec 2023DFT and TD-DFT studies of B3LYP/6-31 g(d,p) with the D2 version of Grimme's dispersion are used to examine the adsorption of a CHO molecule on BeO and MBeO nano-cages (M...
DFT and TD-DFT studies of B3LYP/6-31 g(d,p) with the D2 version of Grimme's dispersion are used to examine the adsorption of a CHO molecule on BeO and MBeO nano-cages (M = K, Mn, or Cu atom). The energy gap for BeO was 8.210 eV, while the M encapsulation decreased its value to 0.685-1.568 eV, whereas the adsorption of the CHO gas decreased the E values for BeO and CuBeO to 4.983 and 0.876 eV and increased its values for KBeO and MnBeO to 1.286 and 1.516 eV, respectively. The M encapsulation enhanced the chemical adsorption of CHO gas with the surface of BeO. The UV-vis spectrum of the BeO nano-cage was dramatically affected by the M encapsulation as well as the adsorption of the CHO gas. In addition, the adsorption energies and the electrical sensitivity of the BeO as well as the MBeO nano-cages to CHO gas could be manipulated with an external electric field. Our results may be fruitful for utilizing BeO as well as MBeO nano-cages as candidate materials for removing and sensing formaldehyde gas.
PubMed: 38202462
DOI: 10.3390/nano14010007 -
PloS One 2023The X-ray energy spectrum is crucial for image quality and dosage assessment in mammography, radiography, fluoroscopy, and CT which are frequently used for the diagnosis...
The X-ray energy spectrum is crucial for image quality and dosage assessment in mammography, radiography, fluoroscopy, and CT which are frequently used for the diagnosis of many diseases including but not limited to patients with cardiovascular and cerebrovascular diseases. X-ray tubes have an electron filament (cathode), a tungsten/rubidium target (anode) oriented at an angle, and a metal filter (aluminum, beryllium, etc.) that may be placed in front of an exit window. When cathode electrons meet the anode, they generate X-rays with varied energies, creating a spectrum from zero to the electrons' greatest energy. In general, the energy spectrum of X-rays depends on the electron beam's energy (tube voltage), target angle, material, filter thickness, etc. Thus, each imaging system's X-ray energy spectrum is unique to its tubes. The primary goal of the current study is to develop a clever method for quickly estimating the X-ray energy spectrum for a variety of tube voltages, filter materials, and filter thickness using a small number of unique spectra. In this investigation, two distinct filters made of beryllium and aluminum with thicknesses of 0.4, 0.8, 1.2, 1.6, and 2 mm were employed to obtain certain limited X-ray spectra for tube voltages of 20, 30, 40, 50, 60, 80, 100, 130, and 150 kV. The three inputs of 150 Multilayer Perceptron (MLP) neural networks were tube voltage, filter type, and filter thickness to forecast the X-ray spectra point by point. After training, the MLP neural networks could predict the X-ray spectra for tubes with voltages between 20 and 150 kV and two distinct filters made of aluminum and beryllium with thicknesses between 0 and 2 mm. The presented methodology can be used as a suitable, fast, accurate and reliable alternative method for predicting X-ray spectrum in medical applications. Although a technique was put out in this work for a particular system that was the subject of Monte Carlo simulations, it may be applied to any genuine system.
Topics: Humans; X-Rays; Aluminum; Beryllium; Radiography; Neural Networks, Computer; Monte Carlo Method
PubMed: 38060542
DOI: 10.1371/journal.pone.0294080 -
Molecules (Basel, Switzerland) Nov 2023In the search for common bonding patterns in pure and mixed clusters of beryllium and magnesium derivatives, the most stable dimers and trimers involving BeX and MgX (X...
In the search for common bonding patterns in pure and mixed clusters of beryllium and magnesium derivatives, the most stable dimers and trimers involving BeX and MgX (X = H, F, Cl) have been studied in the gas phase using B3LYP and M06-2X DFT methods and the G4 ab initio composite procedure. To obtain some insight into their structure, stability, and bonding characteristics, we have used two different energy decomposition formalisms, namely MBIE and LMO-EDA, in parallel with the analysis of the electron density with the help of QTAIM, ELF, NCIPLOT, and AdNDP approaches. Some interesting differences are already observed in the dimers, where the stability sequence observed for the hydrides differs entirely from that of the fluorides and chlorides. Trimers also show some peculiarities associated with the presence of compact trigonal cyclic structures that compete in stability with the more conventional hexagonal and linear forms. As observed for dimers, the stability of the trimers changes significantly from hydrides to fluorides or chlorides. Although some of these clusters were previously explored in the literature, the novelty of this work is to provide a holistic approach to the entire series of compounds by using chemical bonding tools, allowing us to understand the stability trends in detail and providing insights for a significant number of new, unexplored structures.
PubMed: 38005228
DOI: 10.3390/molecules28227507 -
Toxics Nov 2023Technological development has increased the use of chemical elements that have hitherto received scant scientific attention as environmental contaminants. Successful...
Technological development has increased the use of chemical elements that have hitherto received scant scientific attention as environmental contaminants. Successful management of these rare trace elements (RTEs) requires elucidation of their mobility in the soil-plant system. We aimed to determine the capacity of (a common pasture species) to tolerate and accumulate the RTEs Be, Ga, In, La, Ce, Nd, and Gd in a fluvial recent soil. Cadmium was used as a reference as a well-studied contaminant that is relatively mobile in the soil-plant system. Soil was spiked with 2.5-283 mg kg of RTE or Cd salts, representing five, 10, 20, and 40 times their background concentrations in soil. For Be, Ce, In, and La, there was no growth reduction, even at the highest soil concentrations (76, 1132, 10.2, and 874 mg kg, respectively), which resulted in foliar concentrations of 7.1, 12, 0.11, and 50 mg kg, respectively. The maximum no-biomass reduction foliar concentrations for Cd, Gd, Nd, and Ga were 0.061, 0.1, 7.1, and 11 mg kg, respectively. Bioaccumulation coefficients ranged from 0.0030-0.95, and increased Ce < In < Nd ≅ Gd < La ≅ Be ≅ Ga < Cd. Beryllium and La were the RTEs most at risk of entering the food chain via , as their toxicity thresholds were not reached in the ranges tested, and the bioaccumulation coefficient (plant/soil concentration quotient) trends indicated that uptake would continue to increase at higher soil concentrations. In contrast, In and Ce were the elements least likely to enter the food chain. Further research should repeat the experiments in different soil types or with different plant species to test the robustness of the findings.
PubMed: 37999581
DOI: 10.3390/toxics11110929