Unstable Atoms Research Articles

Stability, antibacterial ability, and inhibition of “zinc burning” of amitrole as thermal stabilizer for transparent poly(vinyl chloride)

Amitrole is reported as a novel kind of transparent poly(vinyl chloride) (PVC) thermal stabilizer that has both excellent inhibition of “zinc burning” thermal stability and antibacterial ability in this paper, which provide the possibility of applying the whole PVC industry into medical and food packaging, artificial leather, wire and cable, indoor decoration, and so on. From the results of Congo red test, discoloration test, and dynamic thermal stability test, we could clearly find out that amitrole could effectively replace the unstable chlorine atom and inhibit “zinc burning” of transparent PVC, while the long-term stability should be improved. Next, the stabilization mechanism of amitrole was also confirmed. The antibacterial activity of amitrole was measured by the bacteriostatic ring experiments. It was observed that the PVC films had good antibacterial properties after modified by amitrole. At last, optimal design of the amitrole/ZnSt2 (1:1)/ESBO formulation was studied, which have strong potential as thermal stabilizer to prepare super transparency and antibacterial PVC resin.

Ferroptosis as a New Type of Cell Death and its Role in Cancer Treatment.

Ferroptosis is a recently discovered type of cell death. It is genetically, morphologically, and biochemically distinct from other types of programmed cell death, such as necrosis, apoptosis, and autophagy. The level of intracellular free iron and reactive oxygen species formation are important for ferroptosis activation, which can occur through either of two key inhibitory processes. The first one involves inhibition of cystine transfer into cells by the cystine/glutamate antiporter system (Xc-). Cystine serves as a precursor for the synthesis of glutathione, a major cellular antioxidant. The second one involves the inhibition of glutathione peroxidase 4, which protects cells from lipid peroxidation. Ferroptosis is associated with many metabolic disorders, including neurological diseases and cancer. Molecules involved in the activation of ferroptotic pathways are involved in protecting cells against stress conditions, and in the maintenance of nicotinamide adenine dinucleotide phosphate and glutathione levels, as well as iron homeostasis. Also important is the connection with autophagy, so called ferritinophagy, in which iron is released from lysosomes into the cytosol. Cascade reactions of free unstable iron atoms with other molecules result in the production of reactive oxygen species that initiate the cellular stress that triggers ferroptosis. In diseases such as cancer where cell death inducing mechanisms, including apoptosis, are usually suppressed by genetic changes, the induction of alternative pathways leading to cell death could provide an attractive treatment strategy. In recent years, research into new antimetastatic drugs has focused on the activation of alternative cell death pathways that might overcome disturbed metabolic processes inside cancer cells or the chemotherapy resistance acquired in the course of routine treatment. A number of molecules have been found to induce ferroptosis in tumor cells, suggesting that they may offer new alternatives for anticancer treatment. Key words: cell death - cancer - autophagy - ferroptosis - ferritinophagy - cellular stress - ROS This work was supported by the projects GAČR 17-05838S, MEYS - NPS I - LO1413 and MH CZ- -DRO (MMCI, 00209805). The authors declare they have no potential conflicts of interest concerning drugs, products, or services used in the study. The Editorial Board declares that the manuscript met the ICMJE recommendation for biomedical papers. Accepted: 31. 8. 2018.

The synergistic effect of zinc urate with calcium stearate and commercial assistant stabilizers for stabilizing poly(vinyl chloride)

Zinc urate (Zn3Ur2) is synthesized by the reaction of uric acid and zinc acetate, and the structure of the complex is confirmed by Elemental analysis (EA), Thermogravimetric analysis (TGA) and Infrared spectroscopy (FTIR). The thermal stability effect of Zn3Ur2 with its assistant thermal stabilizers about calcium stearate, β-diketones and polyols on Poly (vinyl chloride) (PVC) is investigated by TG, Congo red test and Discoloration test. The results show that the thermal stability of PVC is increased significantly after Zn3Ur2 is added. Compared with traditional commercial thermal stabilizer such as ZnSt2, Zn3Ur2 can observably delay the “Zinc burning” of PVC and the complete discoloration time is improved to 150 min. This is mainly attributed to the anions in the structure of Zn3Ur2, which could efficiently absorb the HCl released by PVC and have ability to replace unstable chlorine atoms on structure of PVC. Moreover, the mixing of Zn3Ur2 and calcium stearate (CaSt2) can signally promote the long-term thermal stability of PVC. The thermal stability of PVC reaches the optimal state when the ratio of CaSt2/Zn3Ur2 is 1.8/1.2 and its total black time arrives at 210 min. In addition, an excellent synergistic effect can be observed when CaSt2/Zn3Ur2 is combined with other commercial assistant stabilizers. The initial color and long-term stability of PVC containing CaSt2/Zn3Ur2 is markedly improved when Dibenzoylmethane (DBM) is added while Pentaerythritol (PER) can only increase its long-term stability.

CF3 -Inspired Synthesis of Air-Tolerant 9-Phosphaanthracenes that Feature Fluorescence and Crystalline Polymorphs.

9-Phosphaanthracene (dibenzo[b,e]phosphorin, acridophosphine) has attracted interest as one of the heavier acenes. Herein, we demonstrate an efficient synthetic process that provides air-tolerant 1,8-bis(trifluoromethyl)-9-phosphaanthracenes. The sterically encumbered and electron-withdrawing trifluoromethyl (CF3 ) groups are quite advantageous not only to stabilize the intrinsically unstable heavier unsaturated phosphorus atom but also to facilitate construction of the phosphinine skeleton based on a putative increase in aromaticity. The isolated 9-phosphaanthracenes allowed characterization of their fluorescence functionality and planar heteroanthracene frameworks. The crystal structures of 9-phosphaanthracenes are remarkably dependent on the aryl substituents at the 10 position; anthryl-substituted 9-phosphaanthracene showed unique polymorphs that induced different-colored crystals.

An Orbital-Overlap Complement to Atomic Partial Charge.

Atomic partial charges are widely used to predict reactivity. Partial charge alone is often insufficient: the carbons of benzene and cyclobutadiene, or those of diamond, graphene, and C60 , possess nearly identical partial charges and very different reactivities. Our atomic overlap distance complements computed partial charges by measuring the size of orbital lobes that best overlap with the wavefunction around an atom. Compact, chemically stable atoms tend to have overlap distances smaller than chemically soft, unstable atoms. We show here how combining atomic charges and overlap distances captures trends in aromaticity, nucleophilicity, allotrope stability, and substituent effects. Applications to recent experiments in organic chemistry (counterintuitive Lewis base stabilization of alkenyl anions in anionic cyclization) and nanomaterials chemistry (facile doping of the central atom in Au7 hexagons) illustrate this combination's predictive power.

An Orbital‐Overlap Complement to Atomic Partial Charge

AbstractAtomic partial charges are widely used to predict reactivity. Partial charge alone is often insufficient: the carbons of benzene and cyclobutadiene, or those of diamond, graphene, and C60, possess nearly identical partial charges and very different reactivities. Our atomic overlap distance complements computed partial charges by measuring the size of orbital lobes that best overlap with the wavefunction around an atom. Compact, chemically stable atoms tend to have overlap distances smaller than chemically soft, unstable atoms. We show here how combining atomic charges and overlap distances captures trends in aromaticity, nucleophilicity, allotrope stability, and substituent effects. Applications to recent experiments in organic chemistry (counterintuitive Lewis base stabilization of alkenyl anions in anionic cyclization) and nanomaterials chemistry (facile doping of the central atom in Au7 hexagons) illustrate this combination's predictive power.

Validation of Comet assay in Oregon-R and Wild type strains of Drosophila melanogaster exposed to a natural radioactive environment in Brazilian semiarid region

Natural radiation of geological origin is a common phenomenon in Brazil, a country where radioactive agents such as uranium may be often found. As an unstable atom, uranium undergoes radioactive decay with the generation of a series of decay by-products, including radon, which may be highly genotoxic and trigger several pathological processes, among which cancer. Because it is a gas, radon may move freely between cracks and gaps in the ground, seeping upwards into the buildings and in the environment. In this study, two Drosophila melanogaster Meigen (Diptera, Drosophilidae) strains called Oregon-R and Wild (collected in a non-radioactive environment) were exposed to atmospheric radiation in the Lajes Pintadas city, in the semiarid zone of northeastern Brazil. After six days of environmental exposure, the organisms presented genetic damage significantly higher than that of the negative control group. The genotoxic effects observed reinforce the findings of other studies carried out in the same region, which warn about the environmental risks related to natural radioactivity occurrence. The results also validate the use of the Comet assay in hemocytes of D. melanogaster as a sensitive test to detect genotoxicity caused by natural radiation, and the use of a recently collected D. melanogaster strain in the environmental of radon.

Isothermal and non-isothermal calorimetric techniques combined with a simulation approach for studying the decomposition characteristics of di(2,4-dichlorobenzoyl) peroxide

Disasters caused by organic peroxides, such as di(2,4-dichlorobenzoyl) peroxide (DCBP), are mainly attributed to the presence of unstable oxygen atom bonds. In this study, DCBP was investigated through differential scanning calorimetry and thermal activity monitor III, which yielded thermokinetic data to delve into the pure decomposition characteristics of DCBP undergoing chemical reactions. In addition, the thermokinetic data were used to determine the thermal safety parameters through simulation using a best-fit approach based on an appropriately chosen kinetic model and thermal safety software. We found that DCBP decomposes more satisfactorily by an autocatalytic reaction at low temperatures. The apparent activation energy determined through various approaches, such as Kissinger and Ozawa methods, and thermal safety software simulation were studied. Although DCBP decomposition deposits with dioxins, which require major decontamination measures, DCBP is used to produce silicone products globally. The present study establishes threshold thermokinetic parameters for packing and handling thermally sensitive organic peroxides; these thresholds help predict unwarranted runaway reactions, which entail enormous pressure rise and release of toxic by-products to the environment.

Bubble growth from clustered hydrogen and helium atoms in tungsten under a fusion environment

Bubbles seriously degrade the mechanical properties of tungsten and thus threaten the safety of nuclear fusion devices, however, the underlying atomic mechanism of bubble growth from clustered hydrogen and helium atoms is still mysterious. In this work, first-principles calculations are therefore carried out to assess the stability of tungsten atoms around both hydrogen and helium clusters. We find that the closest vacancy-formation energies of interstitial hydrogen and helium clusters are substantially decreased. The first-nearest and second-nearest vacancy-formation energies close to vacancy–hydrogen clusters decrease in a step-like way to ∼0, while those close to vacancy–helium clusters are reduced almost linearly to ∼−5.46 eV when atom number reaches 10. The vacancy-formation energies closest to helium clusters are more significantly reduced than those nearest to hydrogen clusters, whatever the clusters are embedded at interstitial sites or vacancies. The reduction of vacancy-formation energies results in instability and thus emission of tungsten atoms close to interstitial helium and vacancy–helium clusters, which illustrates the experimental results, that the tungsten atoms can be emitted from the vicinity of vacancy–helium clusters. In addition, the emission of unstable tungsten atoms close to hydrogen clusters may become possible once they are disturbed by the environment. The emission of tungsten atoms facilitates the growth and evolution of hydrogen and helium clusters and ultimately the bubble formation. The results also explain the bubble formation even if no displacement damage is produced in tungsten exposed to low-energy hydrogen and helium plasma.

Detection of terrestrial radionuclides with X-ray fluorescence analysis.

This paper provides an overview of analytical methods frequently used to identify terrestrial radionuclides in samples. While radioactivity is normally measured through the ionising radiation produced during the spontaneous decay of unstable atoms, selected radionuclides or their chemical elements can be quantified with instrumental techniques based on stimulated emission or counting of atoms. The advantages and disadvantages of these analytical methods are discussed. Particular attention is paid to X-ray fluorescence analysis of materials containing uranium and thorium. It is also possible to determine the area distributions of these chemical elements in samples with the use of scanning X-ray fluorescence systems.

The effects of precursor concentration and thermal annealing on the growth of zinc oxide nanostructures grown on silicon substrate

This study focuses on the growth of Zinc Oxide (ZnO) nanostructures on SiO2/Si(100) substrate via chemical bath deposition (CBD) with varying NH4OH concentration and annealing temperature. The grown ZnOnanostructures were characterized via SEM-EDS for the surface morphology and elemental composition and UV-Vis spectroscopy for the reflectance measurement. Increasing the concentration of NH4OH produced denser ZnOnanostructures composed of rods having smaller diameter. It is believed that at higher concentration of NH4OH, more Zn(OH)2 seed will act as nucleation site for ZnOformation which suggests higher probability of ZnOgrowth. Thermal annealing increased the average diameter of ZnOnanorods. Annealing provided enough energy for unstable atoms to rearrange into a more suitable position. This would result to larger rods that have been formed in expense of the smaller rods. Furthermore, it is confirmed in the UV-Vis spectroscopy results that ZnOnanostructures were successfully grown on SiO2/Si(100) substrate. This successful growth of ZnOnanostructures is a promising material for solar cell technology.

Molecular dynamics simulation of nanoscale mechanical behaviour of ZnO under nanoscratching and nanoindentation

Molecular dynamics is used to simulate the mechanical behaviour of zinc oxide under nanoscratching and nanoindentation. The effects of indenter speed and substrate temperature on the structure-phase formation, slip vector, radial distribution function, and residual stresses are investigated. Simulation results show that the dislocation loops nucleate and propagate, forming a body-centred tetragonal lattice structure along the slip direction due to high local stress. Furthermore, the dislocation loops nucleate and propagate due to the resolved shear stress along the 45° slip direction under nanoscratching. The average mean biaxial stress and the normal stress of the O layers are –9.35 and –4.36 GPa, respectively, and those of the Zn layers are –0.80 and –0.30 GPa, respectively. This may be attributed to the energetic O atoms, with which unstable atoms have high activation.

Gestión de materiales y residuos radiactivos en la Universidad de Tübingen, Alemania

<p class="p1">Un material radiactivo es toda sustancia o átomo que emite radiaciones ionizantes y no ionizantes; la radiactividad puede ser natural, artificial o inducida. La radiactividad se utiliza en el mundo en ramas de la ciencia como ecología, medicina, agricultura, industria, biología y química. En Costa Rica se usan materiales radiactivos en campos de aplicación industrial, médica y universitaria. Las fuentes radiactivas van desde las de muy baja radiactividad hasta las de muy alta actividad, por ejemplo, Am<span class="s1">241 </span>y Ra<span class="s1">226</span>, utilizadas en centros universitarios costarricenses. No obstante, si los materiales radiactivos no se manipulan correctamente, pueden tener efectos negativos en la salud y el medio ambiente, por lo tanto es necesario tomar medidas preventivas y protectoras. Costa Rica regula el uso de materiales radiactivos mediante el Decreto Ejecutivo Nº 24037-S., sin embargo, no existe formalmente un plan nacional de manejo y eso limita su gestión en las instituciones donde se utilizan y por ende el tratamiento y disposición final de los residuos. El presente trabajo de investigación analiza la gestión en materiales radiactivos que realiza el Laboratorio de Isotopos y Protección Radiológica de la Universidad de Tübingen, Alemania, mediante la determinación y análisis de diferentes acciones y datos relacionados con 1) aspectos administrativos (manuales, protocolos, normativas) y 2) aspectos técnico-operativos (control de la contaminación, infraestructura, equipos y materiales de seguridad, tratamiento de residuos). La información se recopiló y analizó mediante herramientas como cuestionarios, listas de chequeo, entrevistas, visitas de inspección, sesiones de trabajo y revisión de documentos.</p>

Post‐Synthesis Treatment gives Highly Stable Siliceous Zeolites through the Isomorphous Substitution of Silicon for Germanium in Germanosilicates

Germanosilicates, an important family of zeolites with increasing number of members and attractive porosities, but containing a large quantity of unstable Ge atoms in the framework, meet with great obstacles in terms of limited thermal and hydrothermal stability when it comes to practical use. A facile stabilization method thus has been developed to substitute isomorphously Ge atoms for Si atoms, giving rise to ultrastable siliceous analogues of the pristine germanosilicates.

Post‐Synthesis Treatment gives Highly Stable Siliceous Zeolites through the Isomorphous Substitution of Silicon for Germanium in Germanosilicates

AbstractGermanosilicates, an important family of zeolites with increasing number of members and attractive porosities, but containing a large quantity of unstable Ge atoms in the framework, meet with great obstacles in terms of limited thermal and hydrothermal stability when it comes to practical use. A facile stabilization method thus has been developed to substitute isomorphously Ge atoms for Si atoms, giving rise to ultrastable siliceous analogues of the pristine germanosilicates.

Hardware implementation of subtractive clustering for radionuclide identification

Radioactivity is the spontaneous emission of energy from unstable atoms. Radioactive sources have radionuclides. Radionuclide undergoes radioactive decay and emits gamma rays and subatomic particles, constituting the ionizing radiation. The gamma ray energy of a radionuclide is used to determine the identity of gamma emitters present in the source. This paper describes the hardware implementation of subtractive clustering algorithm to perform radionuclide identification. The hardware was proven to be effective for this task, allowing scalability to increase parallelism in the computations.

Increase of Earth Dia Causing Climatic Change

The two types of atoms stable and unstable atoms play the major role in the universe. The space consists of majority of stable atoms in controversy to earth consists of majority of unstable atoms. The attraction and repulsion of unstable atom by stable atom produces a torque. This torque depends on temperature and magnetic field. Thus, the earth rotates about itself. Due to the increase of temperature the diameter of earth increases, that decreases the speed and the spinning of earth; causes climatic change.

Nuclear sciences: A unique contribution to the betterment of the human condition

The sciences and applications of ionizing radiation and radioactivity only started in earnest with the discovery of X-rays by Wilhelm Roentgen in 1895, the discovery of radioactivity by Henri Bequerel in 1896, and the isolation and description of the two new radioactive elements polonium and radium from uranium ore pitchblende by Pierre and Marie Curie shortly thereafter. Until the end of the 19th century the powers of unstable atoms had remained hidden from all cultures, fluorescent glasses containing uranium salts being an exception. Even during early industrialization when silver miners encountered pitchblende1, an ore rich in uranium, this only meant misfortune, the end of silver streaks. The study of radioactivity and ionizing radiation was an important driver in the development of physical, chemical and biological sciences in the 20th century, both for the elucidation of atomic and nuclear forces, and the development of analytical and imaging tools. Albeit there were few industrial or medical applications beyond X-ray imaging in the early years of the 20th century, the public of the industrialized world developed a love ∗IAEA former Deputy Director General. †E-mail: werner.burkart@tele2.at “Pech” in German has two meanings, pitch or bad luck. Hence a proper translation would have been “bad luck glitter”. EPJ Web of Conferences DOI: 10.1051/

Comment on “Effect of entanglement on the decay dynamics of a pair of H(2p) atoms due to spontaneous emission”

Tanabe et al (Phys. Rev. A {\bf 82} 040101(R) 2010) have experimentally demonstrated that the emission properties of unstable atoms in entangled and product states are different. The authors define an apparent decay time as a fitting parameter which falls below the lifetime of the single atom for entangled pairs. We argue that their results about coincidence time spectra are correct, but those concerning lifetimes cannot be considered conclusive because they assume the emission of photons by the two atoms to be independent processes, a doubtful hypothesis for entangled states. We suggest an improved evaluation of the lifetimes based on a rigorous approach, which demands some modifications of the experimental procedure.

GANIL-SPIRAL2: a new era

GANIL presently offers unique opportunities in nuclear physics and in many other fields that arise from not only the provision of low-energy stable beams, fragmentation beams and re-accelerated radioactive species, but also from the availability of a wide range of state-of-the-art spectrometers and instrumentation. A few examples of recent highlights are presented. With the construction of SPIRAL2 over the next few years, GANIL is in a good position to retain its world-leading capability. As selected by the ESFRI committee, the next generation of ISOL facility in Europe is represented by the SPIRAL2 project to be built at GANIL (Caen, France). SPIRAL 2 is based on a high power, CW, superconducting LINAC, delivering 5 mA of deuteron beams at 40MeV (200KW) directed on a C converter+ Uranium target and producing therefore more 1013 fissions/s. The expected radioactive beams intensities in the mass range from A=60 to A=140, will surpass by two order of magnitude any existing facilities in the world. These unstable atoms will be available at energies between few KeV/n to 15 MeV/n. The same driver will accelerate high intensity (10μA to 1 mA), heavier ions (Ar up to Xe) at maximum energy of 14 MeV/n. Under the 7FP program of European Union called *Preparatory phase*, the SPIRAL2 project has been granted a budget of about 4M to build up an international consortium around this new venture. The scientific pillars of the future facility, the status of the construction of SPIRAL2 accelerator and associated physics instruments in collaboration with EU and International partners will be presented.