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Applied Radiation and Isotopes :... Nov 2023Tungsten, tantalum and osmium are important alloying elements in the nuclear technology research and development, particularly in nuclear fission/fusion power plant...
Tungsten, tantalum and osmium are important alloying elements in the nuclear technology research and development, particularly in nuclear fission/fusion power plant material applications. So, data results of the cross sections and emission spectra of neutron-induced reactions are required to predict nuclear responses in these elements. However, the cross sections measurements of (n,2n) reactions on tungsten, tantalum and osmium isotopes are rather limited in the literature. In this case, theoretical approaches are often used for obtaining the cross section data. In this article, theoretical (n,2n) cross sections on W, Ta and Os target nuclei are calculated up to 20 MeV energy, using the simulation codes TALYS 1.95, ALICE/ASH and CEM03.01. Further, the empirical (n,2n) systematics based on the statistical model have been used for predicting the cross section data at ∼14 MeV incident neutrons. The present results from the empirical systematics and model-based calculations are also compared with the literature experimental data, and JENDL-5.0, ENDF/B-VIII, JEFF3.3 and TENDL-2021 libraries. This paper can provide a contribution to complete description of the (n,2n) reactions considering the lack of experimental cross section data.
PubMed: 37639970
DOI: 10.1016/j.apradiso.2023.110999 -
Dalton Transactions (Cambridge, England... Sep 2022We have recently reported a series of half-sandwich ruthenium(II) complexes with curcuminoid ligands showing excellent cytotoxic activities (particularly ionic...
We have recently reported a series of half-sandwich ruthenium(II) complexes with curcuminoid ligands showing excellent cytotoxic activities (particularly ionic derivatives containing PTA (PTA = 1,3,5-triaza-7-phosphaadamantane). In the present study, new members of this family of compounds have been prepared with the objective to investigate the effect of a long hydrophobic chain obtained by replacing the OH-groups, present in curcumin and bisdemethoxycurcumin, with the palmitic acid ester. We report the synthesis of ruthenium(II) and osmium(II) p-cymene derivatives containing palmitic acid curcumin ester ligands ((1,3,6)-3-hydroxy-5-oxohepta-1,3,6-triene-1,7-diyl)bis(2-methoxy-4,1-phenylene)dipalmitate () and ((1,3,6)-3-hydroxy-5-oxohepta-1,3,6-triene-1,7-diyl)bis(4,1-phenylene)dipalmitate (). Complexes [M(II)(cym)(p-curc)/(p-bdcurc)(Cl)] 1-4 (M = Ru or Os) are neutral, whereas [M(II)(cym)(p-curc)/(p-bdcurc)(PTA)][SOCF] 5-8 are salts obtained when the chloride ligand is replaced by the PTA ligand. Stability studies performed on 1-8 in DMSO-PBS under physiological conditions (pH = 7.4) indicate that the complexes remain intact. The complexes exhibit potent and selective cytotoxic activity against an ovarian carcinoma cell line and its cisplatin-resistant form (A2780 and A2780cis), and non-cancerous human embryonic kidney (HEK293T) cells. To define the structure-activity relationships (SAR), the compounds have been compared with other Ru(II) and Os(II) complexes with curcuminoid ligands previously reported. SAR data reveal that the bisdemethoxycurcumin complexes are generally more active and selective than analogous curcumin-containing complexes.
Topics: Antineoplastic Agents; Cell Line, Tumor; Coordination Complexes; Curcumin; Diarylheptanoids; Esters; Female; HEK293 Cells; Humans; Ligands; Organometallic Compounds; Osmium; Ovarian Neoplasms; Palmitic Acid; Ruthenium
PubMed: 35983757
DOI: 10.1039/d2dt02328h -
Methods in Molecular Biology (Clifton,... 2023Postfixation with osmium tetroxide and Epon embedding are essential for the preservation and visualization of subcellular ultrastructures via electron microscopy. These...
Postfixation with osmium tetroxide and Epon embedding are essential for the preservation and visualization of subcellular ultrastructures via electron microscopy. These chemical treatments diminish the fluorescent intensity of most fluorescent proteins in cells, creating a problem for the in-resin correlative light-electron microscopy (CLEM) of Epon-embedded mammalian cultured cells. We found that two green and two far-red fluorescent proteins retain their fluorescence after chemical fixation with glutaraldehyde, osmium tetroxide-staining, dehydration, and polymerization of Epon resins. Consequently, we could observe the fluorescence of fluorescent proteins in ultrathin sections of Epon-embedded cells via fluorescence microscopy, investigate ultrastructures of the cells in the same sections via electron microscopy, and correlate the fluorescent image with the electron microscopic image without chemical or physical distortion of the cells. In other words, referred as "in-resin CLEM" of Epon-embedded samples. This technique also improves the Z-axis resolution of fluorescent images. In this chapter, we introduce the detailed protocol for in-resin CLEM of Epon-embedded mammalian cultured cells using these fluorescent proteins.
Topics: Animals; Cells, Cultured; Electrons; Glutaral; Mammals; Microscopy, Electron; Osmium; Osmium Tetroxide
PubMed: 36107349
DOI: 10.1007/978-1-0716-2667-2_15 -
Accounts of Chemical Research Apr 2023ConspectusAromatic compounds are important in synthetic chemistry, biomedicines, and materials science. As a special type of aromatic complex, transition-metal-based...
ConspectusAromatic compounds are important in synthetic chemistry, biomedicines, and materials science. As a special type of aromatic complex, transition-metal-based metallaaromatics contain at least one transition metal in an aromatic framework. The chemistry of metallaaromatics has seen much progress in computational studies and synthetic methods, but their properties and applications are still emerging. In recent years, we have disclosed a series of metal-centered conjugated polycyclic metallacycles in which a carbon chain is chelated to a metal center through at least three metal-carbon bonds. These are termed carbolong complexes and exhibit good stability to water, oxygen, light, and heat on account of their polydentate chelation and aromaticity, making them easy to handle. Carbolong complexes are not only special π-conjugated aromatics but also organometallics; therefore, they have the properties of both species. In this Account, we showcase the recent advances in their applications based on their different properties.First, carbolong complexes are a special kind of π-conjugated aromatic, with the ability to transmit electrons, allowing them to function as single-molecule conductors and candidates for electron transporting layer materials (ETLs) in solar cells. A series of carbolong complexes have been proved to be useful as achievable ETLs which enhance device performance in both organic solar cells and perovskite solar cells.Second, due to the involvement of d orbitals in the conjugation, carbolong complexes normally exhibit strong and broad absorption, even in some cases extending to the near-infrared region (NIR). The absorbed optical energy can be converted into light, heat, and ultrasound; consequently, carbolong compounds can be used as core moieties in smart materials. For example, 7C carbolong complexes were found to exhibit aggregation-enhanced near-infrared emission (AIEE). Some 12C carbolong complexes have been designed into the core moieties of NIR-responsive polymers, such as cylindrical NIR-responsive materials, self-healing materials, and shape memory materials. In contrast to the stereotypically toxic osmium compounds such as the highly toxic OsO, some osmium carbolong complexes exhibit low cell cytotoxicity and good biocompatibility; consequently, they also have potential applications in the biomedical area. For example, benefiting from broad absorption in the NIR, 9C and 12C carbolong complexes have been used in photoacoustic imaging and photothermal therapy, respectively. In addition, photodynamic therapeutic applications which take advantage of a carbolong peroxo complex are discussed.Third, as special transition-metal complexes chelated by carbon-based ligands, a carbolong peroxo complex has displayed catalytic activity in the dehydrogenation of alcohols and a bimetallic carbolong complex has been used to catalyze difunctionalization reactions of unactivated alkenes.Overall, aromatic carbolong complexes have been applied to photovoltaics, smart materials, phototherapy, and catalytic reactions. Moving forward, we hope that this Account will shed light on future studies and theoretical research and encourage more discoveries of the properties of other metallaaromatics.
PubMed: 36718118
DOI: 10.1021/acs.accounts.2c00750 -
Chemical & Pharmaceutical Bulletin 2022Osmium is defined in the international council for harmonization (ICH-Q3D) guidelines as an element whose concentration can be determined by validated methods including...
Osmium is defined in the international council for harmonization (ICH-Q3D) guidelines as an element whose concentration can be determined by validated methods including microwave-assisted nitric acid digestion and inductively coupled plasma mass spectrometry. However, microwave digestion using nitric acid is known to result in osmium recoveries higher than the theoretical values in spiked tests because of the formation of highly volatile osmium tetroxide in an oxidation reaction. To stabilize osmium, the addition of thiourea as a complexing agent has been tested and proved its utility. It remains unclear whether other compounds can prevent the over-recovery of osmium. In this study, we investigated four compounds, thiourea, ascorbic acid, sodium sulfite, and potassium metabisulfite, that could reduce the overestimation of osmium isotopes. The minimum amounts of thiourea, ascorbic acid, sodium sulfite, and potassium metabisulfite required to stabilize 10 ng/mL osmium in blank matrix were 1.0, 1.0, 2.5, and 2.5 g/L, respectively. The relative standard deviations obtained from 12 analyses for each stabilization solution were less than 3.3% in thiourea, 12.7% in ascorbic acid, 9.0% in sodium sulfite, and 10.6% in potassium metabisulfite. The stabilization solutions were investigated in a digested tablet matrix and were found to be effective. The impact of adding stabilization solutions on the determination of all ICH-Q3D element concentrations was also evaluated. As stabilization solutions had a small or significant impact on the determination of some elements, it was concluded that osmium determination should be conducted independently.
Topics: Hydrogen-Ion Concentration; Isotopes; Mass Spectrometry; Microwaves; Osmium
PubMed: 34980735
DOI: 10.1248/cpb.c21-00739 -
Angewandte Chemie (International Ed. in... Dec 2016We propose the very first "Nernstian biosupercapacitor", a biodevice based on only one redox polymer: poly(vinyl imidazole-co-allylamine)[Os(bpy) Cl], and two...
We propose the very first "Nernstian biosupercapacitor", a biodevice based on only one redox polymer: poly(vinyl imidazole-co-allylamine)[Os(bpy) Cl], and two biocatalysts. At the bioanode PQQ-dependent glucose dehydrogenase reduces the Os moieties at the polymer to Os shifting the Nernst potential of the Os /Os redox couple to negative values. Concomitantly, at the biocathode the reduction of O by means of bilirubin oxidase embedded in the same redox polymer leads to the oxidation of Os to Os shifting the Nernst potential to higher values. Despite the use of just one redox polymer an open circuit voltage of more than 0.45 V was obtained during charging and the charge is stored in the redox polymer at both the bioanode and the biocathode. By connecting both electrodes via a predefined resistor a high power density is obtained for a short time exceeding the steady state power of a corresponding biofuel cell by a factor of 8.
Topics: Glucose 1-Dehydrogenase; Organometallic Compounds; Osmium; Oxidation-Reduction; Oxygen
PubMed: 27805779
DOI: 10.1002/anie.201607144 -
Dalton Transactions (Cambridge, England... Jul 2022Investigations into the reactivity, properties, and applications of osmium(IV) tetraaryl complexes have been hampered by their low yielding syntheses from volatile and...
Investigations into the reactivity, properties, and applications of osmium(IV) tetraaryl complexes have been hampered by their low yielding syntheses from volatile and toxic OsO (typically ≤34%). Here we show that known air-stable M(aryl) compounds (M = Os, Ru; aryl = 2-tolyl, 2,5-xylyl) can be prepared in ≤73% yields using new, less hazardous (OctN)[MX] precursors (M = Os, Ru; X = Cl, Br). This approach also facilitates the preparation of Os(mesityl) (Os3) for the first time, a complex comprising bulky 2,6-dimethyl substituted aryl ligands, albeit in low yield (5%). To better understand these yield extremes, we track, by synthesizing two additional new complexes with different 2-substituted σ-aryl ligands, a clear relationship between the yields of Os(aryl) and ligand steric bulk. Single-crystal X-ray structures of these compounds indicate that the observed yield trend reflects the ease of accommodating aryl substituents into an open pocket that lies directly opposite each M-aryl coordination site. We perform variable-temperature H NMR studies of Os3, utilize a "tetrahedricity" metric to assess geometric distortion in Ru(aryl) and Os(aryl) materials, and calculate cone angle and percentage buried volume metrics to further illustrate and help quantify σ-aryl ligand steric properties. Solution cyclic voltammograms of Os(aryl) show that the potentials of their reversible 1-/0 and 0/1+ redox features can be fine-tuned by varying aryl substituents, and that Os3 exhibits an additional 1+/2+ redox event not previously observed in this class of compounds. Taken together, this work helps to advance the potential application of these relatively underexplored organometallic complexes in established and emerging areas of molecular materials science, such as extended molecular frameworks and self-assembled monolayers, where analogous tetraphenylmethane and silane species (M = C, Si) have been frequently targeted.
PubMed: 35770688
DOI: 10.1039/d2dt01706g -
Organic & Biomolecular Chemistry Jan 2021Olefin 1,2-difunctionalization has emerged as a popular strategy within modern synthetic chemistry for the synthesis of vicinal amino alcohols and derivatives. The... (Review)
Review
Olefin 1,2-difunctionalization has emerged as a popular strategy within modern synthetic chemistry for the synthesis of vicinal amino alcohols and derivatives. The advantage of this approach is the single-step simplicity for rapid diversification, feedstock nature of the olefin starting materials, and the possible modularity of the components. Although there is a vast number of possible iterations of 1,2-olefin difunctionalization, 1,2-amino oxygenation is of particular interest due to the prevalence of both oxygen and nitrogen within pharmaceuticals, natural products, agrochemicals, and synthetic ligands. The Sharpless amino hydroxylation provided seminal results in this field and displayed the value in achieving methods of this nature. However, a vast number of new and novel methods have emerged in recent decades. This review provides a comprehensive review of modern advances in accomplishing 1,2-amino oxygenation of alkenes, 1,3-dienes, alkynes, and allenes that move beyond osmium to a range of other transition metals and more modern strategies such as electrochemical, photochemical, and biochemical reactivity.
PubMed: 33174579
DOI: 10.1039/d0ob01938k -
International Journal of Gynaecology... Mar 2023To study the impact of heavy metals especially tellurium, thallium, and osmium, in recurrent pregnancy loss (RPL) and to study their association with antioxidant status...
OBJECTIVE
To study the impact of heavy metals especially tellurium, thallium, and osmium, in recurrent pregnancy loss (RPL) and to study their association with antioxidant status and DNA damage.
METHODS
This case-control study included women with RPL (n = 30) and healthy pregnant women as control (n = 30). Following blood collection, serum levels of thallium, tellurium, osmium, lead, mercury, and cadmium were estimated by inductively coupled plasma mass spectrophotometer.
RESULTS
Women with RPL exhibited significantly higher levels of heavy metals (P < 0.001) when compared with control women. Intriguingly, increased levels of serum thallium, tellurium, osmium, and lead were negatively correlated with total antioxidant status (P < 0.05). Further, the RPL group demonstrated strong positive correlation between heavy metals (thallium, tellurium, osmium, lead) and DNA damage (P < 0.05). No significant correlation between other heavy metals and markers of cellular damage was noted.
CONCLUSION
Enhanced levels of heavy metals in women with RPL and correlation of thallium, tellurium, osmium, and lead with markers of cellular damage reflect the role of heavy metal poisoning, especially thallium, tellurium, and osmium, as potential risk factor in the etiology underlying recurrent miscarriage.
Topics: Female; Humans; Pregnancy; Thallium; Tellurium; Osmium; Antioxidants; Case-Control Studies; Metals, Heavy
PubMed: 35929844
DOI: 10.1002/ijgo.14390 -
ELife Oct 2022Electron microscopy of biological tissue has recently seen an unprecedented increase in imaging throughput moving the ultrastructural analysis of large tissue blocks...
Electron microscopy of biological tissue has recently seen an unprecedented increase in imaging throughput moving the ultrastructural analysis of large tissue blocks such as whole brains into the realm of the feasible. However, homogeneous, high-quality electron microscopy staining of large biological samples is still a major challenge. To date, assessing the staining quality in electron microscopy requires running a sample through the entire staining protocol end-to-end, which can take weeks or even months for large samples, rendering protocol optimization for such samples to be inefficient. Here, we present an in situ time-lapsed X-ray-assisted staining procedure that opens the 'black box' of electron microscopy staining and allows observation of individual staining steps in real time. Using this novel method, we measured the accumulation of heavy metals in large tissue samples immersed in different staining solutions. We show that the measured accumulation of osmium in fixed tissue obeys empirically a quadratic dependence between the incubation time and sample size. We found that potassium ferrocyanide, a classic reducing agent for osmium tetroxide, clears the tissue after osmium staining and that the tissue expands in osmium tetroxide solution, but shrinks in potassium ferrocyanide reduced osmium solution. X-ray-assisted staining gave access to the in situ staining kinetics and allowed us to develop a diffusion-reaction-advection model that accurately simulates the measured accumulation of osmium in tissue. These are first steps towards staining experiments and simulation-guided optimization of staining protocols for large samples. Hence, X-ray-assisted staining will be a useful tool for the development of reliable staining procedures for large samples such as entire brains of mice, monkeys, or humans.
Topics: Humans; Mice; Animals; Osmium Tetroxide; Osmium; X-Rays; Staining and Labeling; Microscopy, Electron
PubMed: 36263931
DOI: 10.7554/eLife.72147