Acceleration Of Decay Research Articles

Acceleration of emission decay in Ce-doped Gd-containing garnets by aliovalent codoping due to blocking excitation transfer via gadolinium subsystem

Substantially faster scintillators for radiation detectors are currently in demand for future high-luminosity high energy physics experiments and medical imaging devices. To meet this demand, the excitation transfer through Gd-sublattice in Ce-activated garnet-type scintillators is studied by time-resolved cathodoluminescence (CL) and photoluminescence (PL) techniques. The transfer is evidenced in the different decay rate in CL experiments and after resonant photoexcitation of Ce ions and is confirmed by the simulation of excitation transport through gadolinium subsystem and from Gd3+ to Ce3+ ions using the Monte Carlo technique. Energy levels of Gd3+ involved in the transfer are identified. The comparison of the results of time-resolved PL and CL measurements and the simulations of carrier dynamics revealed that the emission decay in Ce-doped Gd-containing garnets is accelerated by aliovalent codoping due to blocking the excitation transfer via gadolinium subsystem.

High virulence Proteus mirabilis strains cause acceleration of decay of fresh-cut fruits

The role of Proteus mirabilis on food safety has not been investigated before. Three P. mirabilis strains (swupm1, swupm2 and swupm3) isolated from fresh-cut fruits were shown to vary in swarming motility, with strains swupm1 and swupm2, but not swupm3 exhibiting the characteristic bull's-eye phenotype. Strains swupm1 and swupm2 grew faster and produced stronger biofilm than swupm3. These strains were all multidrug resistant and exhibited high virulence in Galleria mellonella (100% mortality at around 100 CFU inoculum) with swupm1 being the most virulent one. P. mirabilis was shown to be able to survive in fresh-cut cantaloupe at 4 °C and facilitate the growth of other bacteria. At 25 °C, P. mirabilis could significantly accelerate the decay of fresh-cut fruits. Headspace gas chromatography–ion mobility spectrometry (HS-GC-IMS) analysis showed that P. mirabilis strain swupm1 could cause dramatic changes in the volatile components of fresh-cut cantaloupe, such as ethyl acetate, ethanol and formic acid. This study indicates that P. mirabilis can accelerate the decay of fresh-cut fruits and that the virulence level of these strains seems to be closely associated with the adverse effect of such strains on food quality.

Influence of heavy magnesium codoping on emission decay in Ce-doped multicomponent garnet scintillators

Heavy Mg-codoping substantially increases the emission decay rate of Ce-doped garnet-type scintillators by introducing Mg–Ce centers with a lower barrier for thermal quenching and a channel for temperature-independent nonradiative recombination.

Hepatitis D virus-induced interferon response and administered interferons control cell division-mediated virus spread.

Besides HBV-dependent de novo infection, cell division-mediated spread contributes to HDV persistence and dampens the effect of antivirals that abrogate de novo infection. Nonetheless, the combination of these antivirals with interferons (IFNs) showed strong synergism in recent clinical trials, implying a complementary mode-of-action of IFNs. Therefore, we investigated the effect of IFN response on cell division-mediated HDV spread. Cells infected with HDV were passaged to undergo cell division. The effect of the IFN response was evaluated by blocking HDV-induced IFN activation, by applying different IFN treatment regimens, and by adjusting HDV infection doses. Cell division-mediated HDV spread was highly efficient following infection of HuH7NTCP cells (defective in IFN production), but profoundly restricted in infected IFN-competent HepaRGNTCP cells. Treatment with IFN-α/-λ1 inhibited HDV spread in dividing HuH7NTCP cells, but exhibited a marginal effect on HDV replication in resting cells. Blocking the HDV-induced IFN response with the JAK1/2 inhibitor ruxolitinib or knocking down MDA5 augmented HDV spread in dividing HepaRGNTCP cells. The virus-induced IFN response also destabilized HDV RNA in dividing cells. Moreover, the effect of exogenous IFNs on cell division-mediated HDV spread was more pronounced at low multiplicities of infection with weak virus-induced IFN responses. Both HDV-induced IFN response and exogenous IFN treatment suppress cell division-mediated HDV spread, presumably through acceleration of HDV RNA decay. Our findings demonstrate a novel mode-of-action of IFN, explain the more pronounced effect of IFN therapy in patients with lower HDV serum RNA levels, and provide insights for the development of combination therapies. Chronic hepatitis D is a major health problem. The causative pathogen hepatitis D virus (HDV) can propagate through viral particle-mediated infection and the division of infected cells. Although viral particle-dependent infection can be blocked by recently developed drugs, therapies addressing the cell division route have not been reported. Taking advantage of relevant cell culture models, we demonstrate that the widely used immune modulator interferon can efficiently suppress HDV spread through cell division. This work unveils a new function of interferon and sheds light on potentially curative combination therapies.

Insights on the antiviral mechanisms of action of the TLR1/2 agonist Pam3CSK4 in hepatitis B virus (HBV)-infected hepatocytes

ObjectivesPegylated-interferon-alpha (Peg-IFNα), an injectable innate immune protein, is still used to treat chronically HBV-infected patients, despite its poor tolerability. Peg-IFNα has the advantage over nucleos(t)ide analogues (NAs) to be administrated in finite regimen and to lead to a higher HBsAg loss rate. Yet it would be interesting to improve the efficacy (i.e. while decreasing doses), or replace, this old medicine by novel small molecules/stimulators able to engage innate immune receptors in both HBV replicating hepatocytes and relevant innate immune cells. We have previously identified the Toll-Like-Receptor (TLR)-2 agonist Pam3CSK4 as such a potential novel immune stimulator. The aim of this study was to gain insights on the antiviral mechanisms of action of this agonist in in vitro cultivated human hepatocytes. DesignWe used in vitro models of HBV-infected cells, based on both primary human hepatocytes (PHH) and the non-transformed HepaRG cell line to investigate the MoA of Pam3SCK4 and identify relevant combinations with other approved or investigational drugs. ResultsWe exhaustively described the inhibitory anti-HBV phenotypes induced by Pam3CSK4, which include a strong decrease in HBV RNA production (inhibition of synthesis and acceleration of decay) and cccDNA levels. We confirmed the long-lasting anti-HBV activity of this agonist, better described the kinetics of antiviral events, and demonstrated the specificity of action through the TLR1/2- NF-κB canonical-pathway. Moreover, we found that FEN-1 could be involved in the regulation and inhibitory phenotype on cccDNA levels. Finally, we identified the combination of Pam3CSK4 with IFNα or an investigational kinase inhibitor (called 1C8) as valuable strategies to reduce cccDNA levels and obtain a long-lasting anti-HBV effect in vitro. ConclusionsTLR2 agonists represent possible assets to improve the rate of HBV cure in patients. Further evaluations, including regulatory toxicity studies, are warranted to move toward clinical trials.

Summer sunlight impacts carbon turnover in a spatially heterogeneous Patagonian woodland

PurposeWe evaluated the importance of dry season (summer) sunlight on carbon (C) turnover in a Mediterranean-type climate ecosystem in the context of spatially heterogenous distribution of vegetation.MethodsWe manipulated summer sunlight exposure of litter and soil at the ecosystem scale in a natural Patagonian woodland over two years and evaluated its effect on C turnover in litter and surface soil. We measured decomposition of standing dead litter of dominant grass and shrub species, changes in labile C pools in soil microsites with and without plant litter, and potential enzyme activity of litter and both soil microsites, evaluating seasonal and legacy effects of summer sunlight exposure.ResultsSummer sunlight exposure significantly increased standing litter decomposition for both shrub and grass litter (p < 0.05). Additionally, summer sunlight significantly increased labile carbohydrate availability (saccharification) and potential microbial enzymatic activity of grass (but not shrub) litter. Interestingly, summer sunlight exposure also had effects on soil, reducing by 50% labile organic C while stimulating potential extracellular enzyme activity in both soil microsites, with and without plant litter.ConclusionSummer sunlight accelerates C loss from standing litter and soil consistently across patches of heterogeneously distributed vegetation. In addition, sunlight exposure demonstrated carryover effects on the acceleration of grass litter decay in the following rainy season, when sunlight increased decomposition five times more than in the dry season. These results suggest that summer sunlight is an important and lasting control of C turnover at the ecosystem scale even in seasonally and spatially heterogenous ecosystems.

Compositional engineering of multicomponent garnet scintillators: towards an ultra-accelerated scintillation response

A Czochralski-grown single crystal of GAGG:Ce,Mg allows for a high Ce dopant and Mg codopant concentration in the crystal, resulting in acceleration of scintillation decay down to several nanoseconds at the expense of light yield.

Mycorrhizal effects on decomposition and soil CO2 flux depend on changes in nitrogen availability during forest succession

Abstract Mycorrhizal fungi play a central role in plant nutrition and nutrient cycling, yet our understanding on their effects on free‐living microbes, soil carbon (C) decomposition and soil CO2 fluxes remains limited. Here we used trenches lined with mesh screens of varying sizes to isolate mycorrhizal hyphal effects on soil C dynamics in subtropical successional forests. We found that the presence of mycorrhizal hyphae suppressed soil CO2 fluxes by 17% in early‐successional forests, but enhanced CO2 losses by 20% and 32% in mid‐ and late‐successional forests respectively. The inhibitory effects of mycorrhizal fungi on soil CO2 fluxes in the young stands were associated with changes in soil nitrogen (N) mineralization and microbial activities, suggesting that competition between mycorrhizae and saprotrophs for N likely suppressed soil C decomposition. In the mid‐ and late‐successional stands, mycorrhizal enhancement of CO2 release from soil likely resulted from both hyphal respiration and mycorrhizal‐induced acceleration of organic matter decay. Synthesis. Our results highlight the sensitivity of mycorrhizal fungi‐saprotroph interactions to shifts in nutrient availability and demand, with important consequences for soil carbon dynamics particularly in ecosystems with low nutrient conditions. Incorporating such interactions into models should improve the simulations of forest biogeochemical cycles under global change.

In situ passivation of Ga x In(1−x)P nanowires using radial Al y In(1−y)P shells grown by MOVPE

Ga x In(1−x)P nanowires with suitable bandgap (1.35–2.26 eV) ranging from the visible to near-infrared wavelength have great potential in optoelectronic applications. Due to the large surface-to-volume ratio of nanowires, the surface states become a pronounced factor affecting device performance. In this work, we performed a systematic study of Ga x In(1−x)P nanowires’ surface passivation, utilizing Al y In(1−y)P shells grown in situ by using a metal-organic vapor phase epitaxy system. Time-resolved photoinduced luminescence and time-resolved THz spectroscopy measurements were performed to study the nanowires’ carrier recombination processes. Compared to the bare Ga0.41In0.59P nanowires without shells, the hole and electron lifetime of the nanowires with the Al0.36In0.64P shells are found to be larger by 40 and 1.1 times, respectively, demonstrating effective surface passivation of trap states. When shells with higher Al composition were grown, both lifetimes of free holes and electrons decreased prominently. We attribute the acceleration of PL decay to an increase in the trap states’ density due to the formation of defects, including the polycrystalline and oxidized amorphous areas in these samples. Furthermore, in a separate set of samples, we varied the shell thickness. We observed that a certain shell thickness of approximately ∼20 nm is needed for efficient passivation of Ga0.31In0.69P nanowires. The photoconductivity of the sample with a shell thickness of 23 nm decays 10 times slower compared with that of the bare core nanowires. We concluded that both the hole and electron trapping and the overall charge recombination in Ga x In(1−x)P nanowires can be substantially passivated through growing an Al y In(1−y)P shell with appropriate Al composition and thickness. Therefore, we have developed an effective in situ surface passivation of Ga x In(1−x)P nanowires by use of Al y In(1−y)P shells, paving the way to high-performance Ga x In(1−x)P nanowires optoelectronic devices.

Influence of pH on radical reactions between kynurenic acid and amino acids tryptophan and tyrosine. Part I. Amino acids in free state

In the human eye lens the endogenous chromophores of UV-A light (315–400 nm) are able to sensitize radical reactions leading to protein modifications during normal aging and the cataract progression. Kynurenic acid (KNA−) is the most photochemically active dye of the human eye lens reported to date with pKa(KNAH2•) 5.5 for its radical form. Cataract is thought to develop under oxidative stress which could be accompanied by acidosis, an acidification of the intracellular environment. Protonation of kynurenyl radicals at mildly acidic conditions may change the outcome of radical reactions leading to additional damage to proteins. In this work we investigated the influence of pH on the degradation of initial reagents and the formation of products in photoinduced radical reactions between KNA− and amino acids tryptophan (Trp) and tyrosine (Tyr) in free states. Our results have shown that pH variation has minor influence on kinetics of reagent decay and accumulation of products in reactions between tyrosyl and kynurenic acid radicals. However in the case of Trp a two-fold decrease of the reagent degradation without visible changes in the composition of formed products was observed with pH decrease from 7 to 3. Time-resolved measurements have shown similar acidification-induced two-fold acceleration of decay of kynurenyl and tryptophanyl radicals via Back Electron Transfer (BET) with the restoration of initial reagents. Experiments with tryptophan derivatives with different pKa values for their radical forms point out the protonation of tryptophanyl radical as the driving force for BET acceleration at low pH. Our results demonstrate that the protonation of kynurenyl radical does not change its reactivity towards amino acids radicals but the total yield of radical photodamage decreases with the protonation of tryptophanyl radicals. It could be expected that radical induced damage to proteins will depend on the pKa of tryptophanyl radicals within a protein globule.

Modeling Hepatocellular Carcinoma Cells Dynamics by Serological and Imaging Biomarkers to Explain the Different Responses to Sorafenib and Regorafenib.

Simple SummarySystemic therapy in advanced hepatocellular-carcinomas (HCC) has limited benefits, but some patients show partial responses (PR) and a few even a complete response (CR). Understanding the biological mechanisms could help clinicians in decision-making. Aim of this study was to develop a physic-mathematical model to investigate tumor dynamics using α-fetoprotein (AFP) and protein induced by vitamin K absence-II (PIVKA-II) measures combined with digital imaging. The model was set-up in three prototype patients with CR/PR to sorafenib and PR to regorafenib, and then applied in seven patients with different types of response. Overall, the rate constant of cancer cells production ranged between 0.250–0.372 C × day−1. During therapy, neo-angiogenesis reduction was higher in four CR than in four PR or stable disease (SD) and in two non-responders (median: 83.2% vs. 29.4% vs. 2.0%). Tumor vasculature decay appeared accelerated in CR. We conclude that modeling serological and imaging biomarkers could help personalization of systemic therapy.In advanced HCC, tyrosine-kinase inhibitors obtain partial responses (PR) in some patients and complete responses (CR) in a few. Better understanding of the mechanism of response could be achieved by the radiomic approach combining digital imaging and serological biomarkers (α-fetoprotein, AFP and protein induced by vitamin K absence-II, PIVKA-II) kinetics. A physic-mathematical model was developed to investigate cancer cells and vasculature dynamics in three prototype patients receiving sorafenib and/or regorafenib and applied in seven others for validation. Overall four patients showed CR, two PR, two stable-disease (SD) and two progressive-disease (PD). The rate constant of cancer cells production was higher in PD than in PR-SD and CR (median: 0.398 vs. 0.325 vs. 0.316 C × day−1). Therapy induced reduction of neo-angiogenesis was greater in CR than in PR-SD and PD (median: 83.2% vs. 29.4% and 2.0%), as the reduction of cell-proliferation (55.2% vs. 7.6% and 0.7%). An additional dose-dependent acceleration of tumor vasculature decay was also observed in CR. AFP and cancer cells followed the same kinetics, whereas PIVKA-II time/dose dependent fluctuations were influenced also by tissue ischemia. In conclusion, pending confirmation in a larger HCC cohort, modeling serological and imaging biomarkers could be a new tool for systemic therapy personalization.

Deactivation Kinetics of ZSM‐5 by Coke in Ethanol‐to‐Hydrocarbons Process

AbstractConversion of ethanol to hydrocarbons by porous zeolite ZSM‐5 is a sustainable alternative compared to crude oil, gas or coal conversion. A quantification and description of micro‐ and macroscopic deactivation kinetics with basic transport and reactor models reveals deeper insight into the dynamics of coking and product formation at varying contact time. A new first order deactivation model helps to separate linear deactivation and autocatalytic acceleration of catalyst decay. A deeper look into product formation reveals a change in selectivity during initiation and deactivation phase from bigger build‐up C5+ to smaller cracking products C3 after formation of coke precursors, which does not coincide with site‐loss and reduction of contact time alone. Thereby, deactivation and switching selectivity in the hydrocarbon pool concept become more deterministic, which paves the way to more selective ethanol conversion processes.

Quantum Anti-Zeno Effect in Nuclear β DecaySupported by the National Natural Science Foundation of China (Grant Nos. 11822503 and 11575082), and the Fundamental Research Funds for the Central Universities (Nanjing University).

The acceleration of decay induced by frequency measurements, namely the quantum anti-Zeno effect (AZE), was first predicted by Kofman and Kurizki [Nature 405 (2000) 546]. The effect of the frequency measurements on nuclear β decay rate is analyzed based on the time-dependent perturbation theory. We present a detailed calculation of the decay rates of 3H, 60Co (β − type), 22Na, 106Ag (β + type) and 18F, 57Co and 111Sn (EC type) under frequency measurements. It is found that the effects of frequency measurements on the decay rates of β + and β − cases are different from the case of EC, and the smaller the β decay energy is, the more favorable it is to observe the AZE in experiment. Based on our analysis, it is suggested that possible experimental candidates should have a small decay energy and a reasonable half life (such as 3H) for observing the AZE in β decay.

PNU-120596, a positive allosteric modulator of mammalian α7 nicotinic acetylcholine receptor, is a negative modulator of ligand-gated chloride-selective channels of the gastropod Lymnaea stagnalis.

Excitatory α7 neuronal nicotinic receptors (nAChR) are widely expressed in the central and peripheral nervous and immune systems and are important for learning, memory, and immune response regulation. Specific α7 nAChR ligands, including positive allosteric modulators are promising to treat cognitive disorders, inflammatory processes, and pain. One of them, PNU-120596, highly increased the neuron response to α7 agonists and retarded desensitization, showing selectivity for α7 as compared to heteromeric nAChRs, but was not examined at the inhibitory ligand-gated channels. We studied PNU-120596 action on anion-conducting channels using voltage-clamp techniques: it slightly potentiated the response of human glycine receptors expressed in PC12 cells, of rat GABAA receptors in cerebellar Purkinje cells and mouse GABAA Rs heterologously expressed in Xenopus oocytes. On the contrary, PNU-120596 exerted an inhibitory effect on the receptors mediating anion currents in Lymnaea stagnalis neurons: two nAChR subtypes, GABA and glutamate receptors. Acceleration of the current decay, contrary to slowing down desensitization in mammalian α7 nAChR, was observed in L. stagnalis neurons predominantly expressing one of the two nAChR subtypes. Thus, PNU-120596 effect on these anion-selective nAChRs was just opposite to the action on the mammalian cation-selective α7 nAChRs. A comparison of PNU-120596 molecule docked to the models of transmembrane domains of the human α7 AChR and two subunits of L. stagnalis nAChR demonstrated some differences in contacts with the amino acid residues important for PNU-120596 action on the α7 nAChR. Thus, our results show that PNU-120596 action depends on a particular subtype of these Cys-loop receptors.

Luminescence and scintillation properties of Ce3+-doped SiO2–Al2O3–BaF2–Gd2O3 glasses

Ce3+-doped glasses with composition of (65-x)SiO2 − 20Al2O3 –15BaF2 -xGd2O3 (x = 5, 10, 15, 20 and 25) were synthesized under CO atmosphere by melt-quenching method. The photoluminescence (PL) emission due to Ce3+: 5d1 → 4f transition was red-shifted with increasing Gd2O3 content. The acceleration of PL decay was observed with increasing Gd2O3 content. The scintillation efficiency of about 100% of the Bi4Ge3O12 scintillator was obtained for a 10%Gd2O3 containing glass while a high light yield (LY) of 2050 photons/MeV and energy resolution of 15.8% at 662 keV γ rays was obtained for a 15%Gd2O3 containing glass. The integrating-time dependence of LY value and LY ratio (α/γ ratio) under excitation with α- and γ-rays were also measured.

Loschmidt Echo and Fidelity Decay Near an Exceptional Point

AbstractNon‐Hermitian classical and open quantum systems near an exceptional point (EP) are known to undergo strong deviations in their dynamical behavior under small perturbations or slow cycling of parameters as compared to Hermitian systems. Such a strong sensitivity is at the heart of many interesting phenomena and applications, such as the asymmetric breakdown of the adiabatic theorem, enhanced sensing, non‐Hermitian dynamical quantum phase transitions, and photonic catastrophe. Like for Hermitian systems, the sensitivity to perturbations on the dynamical evolution can be captured by Loschmidt echo and fidelity after imperfect time reversal or quench dynamics. Here, a rather counterintuitive phenomenon in certain non‐Hermitian systems near an EP is disclosed, namely the deceleration (rather than acceleration) of the fidelity decay and improved Loschmidt echo as compared to their Hermitian counterparts, despite large (non‐perturbative) deformation of the energy spectrum introduced by the perturbations. This behavior is illustrated by considering the fidelity decay and Loschmidt echo for the single‐particle hopping dynamics on a tight‐binding lattice under an imaginary gauge field.

MS-CASPT2 Studies on the Photophysics of Selenium-Substituted Guanine Nucleobase.

The MS-CASPT2 method has been employed to optimize minimum-energy structures of 6-selenoguanine (6SeGua) and related two- and three-state intersection structures in and between the lowest five electronic states, i.e., S2(1ππ*), S1(1nπ*), T2(3nπ*), T1(3ππ*), and S0. In combination with MS-CASPT2 calculated linearly interpolated internal coordinate paths, the photophysical mechanism of 6SeGua has been proposed. The initially populated S2(1ππ*) state decays to either S1(1nπ*) or T2(3nπ*) states through a three-state S2/S1/T2 intersection point. The large S2/T2 spin–orbit coupling of 435 cm–1, according to the classical El-Sayed rule, benefits the S2 → T2 intersystem crossing process. The S1(1nπ*) state that stems from the S2 → S1 internal conversion process at the S2/S1/T2 intersection point can further jump to the T2(3nπ*) state through the S1 → T2 intersystem crossing process. This process does not comply with the El-Sayed rule, but it is still related to a comparatively large spin–orbit coupling of 39 cm–1 and is expected to occur relatively fast. Finally, the T2(3nπ*) state, which is populated from the above S2 → T2 and S1 → T2 intersystem crossing processes, decays to the T1(3ππ*) state via an internal conversion process. Because there is merely a small energy barrier of 0.11 eV separating the T1(3ππ*) minimum and an energetically allowed two-state T1/S0 intersection point, the T1(3ππ*) state still can decay to the S0 state quickly, which is also enhanced by a large T1/S0 spin–orbit coupling of 252 cm–1. Our proposed mechanism explains experimentally observed ultrafast intersystem crossing processes in 6SeGua and its 835-fold acceleration of the T1 state decay to the S0 state compared with 6tGua. Finally, we have found that the ground-state electronic structure of 6SeGua has more apparent multireference character.

Suppression of the slow scintillation component of Pr:Lu3Al5O12 transparent ceramics by increasing Pr concentration

Pr:Lu3Al5O12 transparent ceramics with different doping concentrations (0% − 1 at%) were fabricated using the solid-state reaction and vacuum sintering method. The influence of doping concentration on the luminescent properties was investigated in detail. The 5d-4f emission slightly redshifts with the increase of doping concentration under UV light and X-ray excitation. The slow emission below 290 nm related to antisite defects can be suppressed by the increase of doping concentration at room temperature. The suppression of exciton related emission around 250 nm at 77 K is remarkable. The 0.3 at% Pr doped ceramics show the highest light yield that is 6900 ph/MeV with 1 μs shaping time under the excitation of γ-rays (137Cs). There exists slow components of scintillation process in all the Pr-doped transparent ceramics. Higher doping concentration was found to be beneficial for the suppression of the slow components in the scintillation response and therefore acceleration of the scintillation decay and light yield increase up to certain level. These effects are mainly due to competition of Pr3+ ions with the antisite defects for charge carrier capture in the scintillation process which is also supported by the trends observed in the TSL measurements.

Photoinduced Preparation of Bandgap-Engineered Garnet Powders

The indirect photochemical synthesis for the preparation of bandgap- or defect-engineered multicomponent garnet powders from aqueous solutions was investigated. Gd3(Ga,Al)5O12 (GGAG) doped with Ce or Ce + Eu and Lu3(Al,Sb)5O12 doped with Eu were produced by calcination of the prepared solid precursors at various conditions and their structural and luminescence properties including decay curves were thoroughly studied. In GGAG:Ce, the content of Ga was shown to have strong impact on the lattice parameter and position of the Ce3+ 5 d - $4f$ emission. To induce the formation of Ce4+ ions as defects competing with electron traps, Mg2+ ions were added into the solutions and calcination in air was examined. Both factors were shown to cause the decrease of Ce3+ emission intensity and acceleration of luminescence decay in a similar way. The doping with Sb(III) required calcination of solid precursors in inert atmosphere to prevent formation of an unknown pyrochlore-type phase containing Sb(V). Low temperatures were needed to limit Sb2O3 evaporation during calcination.

On the Nature of the Cherdyntsev–Chalov Effect

It is shown that the Cherdyntsev–Chalov effect, usually presented as the separation of even isotopes of uranium upon their transition from the solid to the liquid phase, can include initiated acceleration of the radioactive decay of uranium-238 nuclei during the formation of cracks in geologically (seismic and volcanically) active zones of the Earth’s crust. The fissuring of the solid-phase medium leads to an increase in mechanical tensile stress and the emergence of strong local electric fields, resulting in the injection of chemical-scale high-energy electrons into the aqueous phase of the cracks. Under these conditions, the e− catalytic decay of uranium-238 nucleus studied earlier can occur during the formation of metastable protactinium-238 nuclei with locally distorted nucleon structure, which subequently undergo β–decay with the formation of thorium-234 and helium-4 nuclei as products of the fission of the initial uranium-238 nucleus with a characteristic period of several years. The observed increased activity of uranium-234 nuclei that form during the subsequent β-decay of thorium and then protactinium is associated with the initiated fission of uranium-238. The possibility is discussed of developing thermal power by using existing wastes from uranium production that contain uranium-238 to activate this isotope through the mechanochemical processing of these wastes in aqueous media with the formation of 91 238 Pa isu , the half-life of which is several years.