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1.
Front Chem ; 10: 976635, 2022.
Article in English | MEDLINE | ID: mdl-36092655

ABSTRACT

Flerovium (Fl, element 114) is the heaviest element chemically studied so far. To date, its interaction with gold was investigated in two gas-solid chromatography experiments, which reported two different types of interaction, however, each based on the level of a few registered atoms only. Whereas noble-gas-like properties were suggested from the first experiment, the second one pointed at a volatile-metal-like character. Here, we present further experimental data on adsorption studies of Fl on silicon oxide and gold surfaces, accounting for the inhomogeneous nature of the surface, as it was used in the experiment and analyzed as part of the reported studies. We confirm that Fl is highly volatile and the least reactive member of group 14. Our experimental observations suggest that Fl exhibits lower reactivity towards Au than the volatile metal Hg, but higher reactivity than the noble gas Rn.

2.
Front Chem ; 9: 753738, 2021.
Article in English | MEDLINE | ID: mdl-34917588

ABSTRACT

Nihonium (Nh, element 113) and flerovium (Fl, element 114) are the first superheavy elements in which the 7p shell is occupied. High volatility and inertness were predicted for Fl due to the strong relativistic stabilization of the closed 7p 1/2 sub-shell, which originates from a large spin-orbit splitting between the 7p 1/2 and 7p 3/2 orbitals. One unpaired electron in the outermost 7p 1/2 sub-shell in Nh is expected to give rise to a higher chemical reactivity. Theoretical predictions of Nh reactivity are discussed, along with results of the first experimental attempts to study Nh chemistry in the gas phase. The experimental observations verify a higher chemical reactivity of Nh atoms compared to its neighbor Fl and call for the development of advanced setups. First tests of a newly developed detection device miniCOMPACT with highly reactive Fr isotopes assure that effective chemical studies of Nh are within reach.

3.
Phys Rev Lett ; 126(3): 032503, 2021 Jan 22.
Article in English | MEDLINE | ID: mdl-33543956

ABSTRACT

A nuclear spectroscopy experiment was conducted to study α-decay chains stemming from isotopes of flerovium (element Z=114). An upgraded TASISpec decay station was placed behind the gas-filled separator TASCA at the GSI Helmholtzzentrum für Schwerionenforschung in Darmstadt, Germany. The fusion-evaporation reactions ^{48}Ca+^{242}Pu and ^{48}Ca+^{244}Pu provided a total of 32 flerovium-candidate decay chains, of which two and eleven were firmly assigned to ^{286}Fl and ^{288}Fl, respectively. A prompt coincidence between a 9.60(1)-MeV α particle event and a 0.36(1)-MeV conversion electron marked the first observation of an excited state in an even-even isotope of the heaviest man-made elements, namely ^{282}Cn. Spectroscopy of ^{288}Fl decay chains fixed Q_{α}=10.06(1) MeV. In one case, a Q_{α}=9.46(1)-MeV decay from ^{284}Cn into ^{280}Ds was observed, with ^{280}Ds fissioning after only 518 µs. The impact of these findings, aggregated with existing data on decay chains of ^{286,288}Fl, on the size of an anticipated shell gap at proton number Z=114 is discussed in light of predictions from two beyond-mean-field calculations, which take into account triaxial deformation.

4.
Phys Rev Lett ; 121(2): 022502, 2018 Jul 13.
Article in English | MEDLINE | ID: mdl-30085703

ABSTRACT

Lifetimes of the first excited 2^{+} and 4^{+} states in the extremely neutron-deficient nuclide ^{172}Pt have been measured for the first time using the recoil-distance Doppler shift and recoil-decay tagging techniques. An unusually low value of the ratio B(E2:4_{1}^{+}→2_{1}^{+})/B(E2:2_{1}^{+}→0_{gs}^{+})=0.55(19) was found, similar to a handful of other such anomalous cases observed in the entire Segré chart. The observation adds to a cluster of a few extremely neutron-deficient nuclides of the heavy transition metals with neutron numbers N≈90-94 featuring the effect. No theoretical model calculations reported to date have been able to explain the anomalously low B(E2:4_{1}^{+}→2_{1}^{+})/B(E2:2_{1}^{+}→0_{gs}^{+}) ratios observed in these cases. Such low values cannot, e.g., be explained within the framework of the geometrical collective model or by algebraic approaches within the interacting boson model framework. It is proposed that the group of B(E2:4_{1}^{+}→2_{1}^{+})/B(E2:2_{1}^{+}→0_{gs}^{+}) ratios in the extremely neutron-deficient even-even W, Os, and Pt nuclei around neutron numbers N≈90-94 reveal a quantum phase transition from a seniority-conserving structure to a collective regime as a function of neutron number. Although a system governed by seniority symmetry is the only theoretical framework for which such an effect may naturally occur, the phenomenon is highly unexpected for these nuclei that are not situated near closed shells.

5.
Phys Rev Lett ; 112(17): 172501, 2014 May 02.
Article in English | MEDLINE | ID: mdl-24836239

ABSTRACT

The superheavy element with atomic number Z=117 was produced as an evaporation residue in the (48)Ca+(249)Bk fusion reaction at the gas-filled recoil separator TASCA at GSI Darmstadt, Germany. The radioactive decay of evaporation residues and their α-decay products was studied using a detection setup that allowed measuring decays of single atomic nuclei with half-lives between sub-µs and a few days. Two decay chains comprising seven α decays and a spontaneous fission each were identified and are assigned to the isotope (294)117 and its decay products. A hitherto unknown α-decay branch in (270)Db (Z = 105) was observed, which populated the new isotope (266)Lr (Z = 103). The identification of the long-lived (T(1/2) = 1.0(-0.4)(+1.9) h) α-emitter (270)Db marks an important step towards the observation of even more long-lived nuclei of superheavy elements located on an "island of stability."

6.
Phys Rev Lett ; 111(11): 112502, 2013 Sep 13.
Article in English | MEDLINE | ID: mdl-24074079

ABSTRACT

A high-resolution α, x-ray, and γ-ray coincidence spectroscopy experiment was conducted at the GSI Helmholtzzentrum für Schwerionenforschung. Thirty correlated α-decay chains were detected following the fusion-evaporation reaction 48Ca + 243Am. The observations are consistent with previous assignments of similar decay chains to originate from element Z=115. For the first time, precise spectroscopy allows the derivation of excitation schemes of isotopes along the decay chains starting with elements Z>112. Comprehensive Monte Carlo simulations accompany the data analysis. Nuclear structure models provide a first level interpretation.

7.
Phys Rev Lett ; 109(1): 012501, 2012 Jul 06.
Article in English | MEDLINE | ID: mdl-23031099

ABSTRACT

The rotational band structure of the Z=104 nucleus (256)Rf has been observed up to a tentative spin of 20ℏ using state-of-the-art γ-ray spectroscopic techniques. This represents the first such measurement in a superheavy nucleus whose stability is entirely derived from the shell-correction energy. The observed rotational properties are compared to those of neighboring nuclei and it is shown that the kinematic and dynamic moments of inertia are sensitive to the underlying single-particle shell structure and the specific location of high-j orbitals. The moments of inertia therefore provide a sensitive test of shell structure and pairing in superheavy nuclei which is essential to ensure the validity of contemporary nuclear models in this mass region. The data obtained show that there is no deformed shell gap at Z=104, which is predicted in a number of current self-consistent mean-field models.

8.
Phys Rev Lett ; 102(21): 212501, 2009 May 29.
Article in English | MEDLINE | ID: mdl-19519098

ABSTRACT

The rotational band structure of 255Lr has been investigated using advanced in-beam gamma-ray spectroscopic techniques. To date, 255Lr is the heaviest nucleus to be studied in this manner. One rotational band has been unambiguously observed and strong evidence for a second rotational structure was found. The structures are tentatively assigned to be based on the 1/2-[521] and 7/2-[514] Nilsson states, consistent with assignments from recently obtained alpha decay data. The experimental rotational band dynamic moment of inertia is used to test self-consistent mean-field calculations using the Skyrme SLy4 interaction and a density-dependent pairing force.

10.
J Eur Acad Dermatol Venereol ; 19(6): 753-5, 2005 Nov.
Article in English | MEDLINE | ID: mdl-16268887

ABSTRACT

Mefenamic acid is a common widely prescribed drug with analgesic activity. Authors report two cases of multifocal fixed drug eruption induced by mefenamic acid. Cases were diagnosed on basis of clinical examination and histopathology of skin lesion. Only a few cases have been reported in the literature and these are the first two described in Greece.


Subject(s)
Anti-Inflammatory Agents, Non-Steroidal/adverse effects , Drug Eruptions/diagnosis , Mefenamic Acid/adverse effects , Adult , Aged , Diagnosis, Differential , Humans , Male
11.
Dermatol Online J ; 11(2): 10, 2005 Aug 01.
Article in English | MEDLINE | ID: mdl-16150218

ABSTRACT

Acrokeratosis verruciformis of Hopf is an autosomal dominant genodermatosis usually presenting with multiple planar wart-like lesions, typically observed on the dorsum of the hands and feet. The disease is very rare and the pathogenesis remains unknown. Considerable controversy surrounds the nature and relationship of acrokeratosis and Darier disease and whether they are manifestations of one genetic abnormality. We describe the case of a 19-year-old man seen in our clinic with skin-coloured, flat, warty papules localized to the dorsum of the hands and feet. Both clinical and histological findings were compatible with acrokeratosis verruciformis. We also review the disease, particularly its relation with Darier disease and therapeutical options.


Subject(s)
Foot Dermatoses/pathology , Hand Dermatoses/pathology , Keratosis/pathology , Adult , Humans , Male
12.
Clin Rheumatol ; 22(3): 244-7, 2003 Sep.
Article in English | MEDLINE | ID: mdl-14505221

ABSTRACT

Acute febrile neutrophilic dermatosis or Sweet's syndrome is a rare disease. We describe a patient with oligoarthritis, increased liver enzymes and vasculitis. One year later the patient is free of symptoms. Diseases mimicking Sweet's syndrome have been excluded.


Subject(s)
Arthritis, Rheumatoid/complications , Sweet Syndrome/complications , Vasculitis/complications , Arthritis, Rheumatoid/pathology , Biopsy, Needle , Follow-Up Studies , Humans , Immunohistochemistry , Male , Middle Aged , Risk Assessment , Severity of Illness Index , Sweet Syndrome/pathology , Vasculitis/pathology
13.
Allergy ; 48(3): 142-6, 1993 Apr.
Article in English | MEDLINE | ID: mdl-8506978

ABSTRACT

The distribution of IgE in a large randomly stratified Greek population sample was determined in 1187 subjects (793 men and 394 women) aged between 20 and 60 years. Skin prick testing was performed and serum total IgE expressed in iu/ml was measured by Phadebas PRIST: the data are presented as the geometric mean. Subjects were classified as atopic (257 men, 118 women) and nonatopic (536 men, 276 women) according to the results of skin testing with various aeroallergens. At any age, atopic males (120.5 vs 38 iu/ml) and females (99.8 vs 29.3 iu/ml) had higher mean IgE levels, as compared to nonatopic subjects (P < 0.0001). In our adult nonatopic sample, IgE levels did not differ with age (P > 0.05). At any age, nonatopic males had higher (38 iu/ml) mean IgE levels than nonatopic females (29.3 iu/ml) (P < 0.05). The comparison of normal IgE values (nonatopic subjects) from this study with those reported by other investigators revealed that Greek adult males and females had higher IgE levels than populations from other nations. Our results represent the first report on reference values regarding serum total IgE in Greek adults.


Subject(s)
Immunoglobulin E/blood , Skin Tests , Adult , Age Factors , Allergens , Canada , Female , Greece , Humans , Hypersensitivity/etiology , Hypersensitivity/immunology , Male , Middle Aged , Reference Values , Sex Characteristics , United States
14.
Am Heart J ; 117(5): 1035-41, 1989 May.
Article in English | MEDLINE | ID: mdl-2469329

ABSTRACT

The significance of exercise-induced ST segment depression in supraventricular extrasystoles (STx), in the preceding sinus beats (STs), as well as the significance of the difference between the two of them (STx-s), was studied in 96 patients with angiographically documented coronary artery disease (CAD) (group A)--34 with myocardial infarction (group A1) and 62 without (group A2)--compared to 37 subjects with normal coronary arteries (group B). All patients had supraventricular extrasystoles during exercise testing, the results of which were positive in 72 (75%) patients in group A and six (16.2%) patients in group B (sensitivity 75%, specificity 84%). Among patients in group A STx was greater than STs (1.7 +/- 1.0 vs 1.2 +/- 0.8 mm; p less than 0.001), and STx-s was positive in 70 (sensitivity 73%), whereas in group A2 there were 44 patients with these values (sensitivity 71%). Among patients in group B no statistically significant difference was found between STx and STx (0.4 +/- 0.6 vs 0.6 +/- 0.7 mm; p = NS), whereas STx-s was positive in three (specificity 92%). Among the 24 patients in group A with false negative results of exercise tests, 15 (62.5%) had a positive STx-s, whereas of the 17 patients in group A2 with false negative results, 10 (58.8%) had a positive STx-s. Among the six patients in group B with false positive exercise test results, the STx-s was positive in two.(ABSTRACT TRUNCATED AT 250 WORDS)


Subject(s)
Cardiac Complexes, Premature/physiopathology , Coronary Disease/physiopathology , Electrocardiography , Exercise Test , Cardiac Complexes, Premature/etiology , Coronary Disease/complications , Coronary Disease/diagnosis , Exercise Test/standards , Female , Heart Ventricles , Humans , Male , Middle Aged , Sensitivity and Specificity
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