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1.
Phys Rev Lett ; 131(25): 253002, 2023 Dec 22.
Artigo em Inglês | MEDLINE | ID: mdl-38181339

RESUMO

We present the measurements of individual bound electron g factors of ^{20}Ne^{9+} and ^{22}Ne^{9+} on the relative level of 0.1 parts per billion. The comparison with theory represents the most stringent test of bound-state QED in strong electric fields. A dedicated mass measurement results in m(^{20}Ne)=19.992 440 168 77(9) u, which improves the current literature value by a factor of 18, disagrees by 4 standard deviations, and represents the most precisely measured mass value in atomic mass units. Together, these measurements yield an electron mass on the relative level of 0.1 ppb with m_{e}=5.485 799 090 99(59)×10^{-4} u as well as a factor of seven improved m(^{22}Ne)=21.991 385 098 2(26) u.

2.
Phys Rev Lett ; 127(7): 072502, 2021 Aug 13.
Artigo em Inglês | MEDLINE | ID: mdl-34459634

RESUMO

The cyclotron frequency ratio of ^{187}Os^{29+} to ^{187}Re^{29+} ions was measured with the Penning-trap mass spectrometer PENTATRAP. The achieved result of R=1.000 000 013 882(5) is to date the most precise such measurement performed on ions. Furthermore, the total binding-energy difference of the 29 missing electrons in Re and Os was calculated by relativistic multiconfiguration methods, yielding the value of ΔE=53.5(10) eV. Finally, using the achieved results, the mass difference between neutral ^{187}Re and ^{187}Os, i.e., the Q value of the ß^{-} decay of ^{187}Re, is determined to be 2470.9(13) eV.

3.
Nature ; 581(7806): 42-46, 2020 05.
Artigo em Inglês | MEDLINE | ID: mdl-32376960

RESUMO

State-of-the-art optical clocks1 achieve precisions of 10-18 or better using ensembles of atoms in optical lattices2,3 or individual ions in radio-frequency traps4,5. Promising candidates for use in atomic clocks are highly charged ions6 (HCIs) and nuclear transitions7, which are largely insensitive to external perturbations and reach wavelengths beyond the optical range8 that are accessible to frequency combs9. However, insufficiently accurate atomic structure calculations hinder the identification of suitable transitions in HCIs. Here we report the observation of a long-lived metastable electronic state in an HCI by measuring the mass difference between the ground and excited states in rhenium, providing a non-destructive, direct determination of an electronic excitation energy. The result is in agreement with advanced calculations. We use the high-precision Penning trap mass spectrometer PENTATRAP to measure the cyclotron frequency ratio of the ground state to the metastable state of the ion with a precision of 10-11-an improvement by a factor of ten compared with previous measurements10,11. With a lifetime of about 130 days, the potential soft-X-ray frequency reference at 4.96 × 1016 hertz (corresponding to a transition energy of 202 electronvolts) has a linewidth of only 5 × 10-8 hertz and one of the highest electronic quality factors (1024) measured experimentally so far. The low uncertainty of our method will enable searches for further soft-X-ray clock transitions8,12 in HCIs, which are required for precision studies of fundamental physics6.

4.
Phys Rev Lett ; 124(11): 113001, 2020 Mar 20.
Artigo em Inglês | MEDLINE | ID: mdl-32242713

RESUMO

First ever measurements of the ratios of free cyclotron frequencies of heavy, highly charged ions with Z>50 with relative uncertainties close to 10^{-11} are presented. Such accurate measurements have become realistic due to the construction of the novel cryogenic multi-Penning-trap mass spectrometer PENTATRAP. Based on the measured frequency ratios, the mass differences of five pairs of stable xenon isotopes, ranging from ^{126}Xe to ^{134}Xe, have been determined. Moreover, the first direct measurement of an electron binding energy in a heavy highly charged ion, namely of the 37th atomic electron in xenon, with an uncertainty of a few eV is demonstrated. The obtained value agrees with the calculated one using two independent, different implementations of the multiconfiguration Dirac-Hartree-Fock method. PENTATRAP opens the door to future measurements of electron binding energies in highly charged heavy ions for more stringent tests of bound-state quantum electrodynamics in strong electromagnetic fields and for an investigation of the manifestation of light dark matter in isotopic chains of certain chemical elements.

5.
Klin Lab Diagn ; 64(11): 659-662, 2019.
Artigo em Russo | MEDLINE | ID: mdl-31747493

RESUMO

To develop predictive model of damage of nervous system on the basis of definition of concentration of interleukins-23, 12p40 and also a glial fibrillar acid protein (GFAP) in liquor of patients with various forms of syphilis. Comprehensive laboratory examination of patients with neurosyphilis and syphilis without specific damage of nervous system who were observed in venereologic office of BOUZAS of OO «Clinical Dermatovenerologic Clinic¼ of Omsk is conducted. To all patients were carried out: a serological blood analysis, serological and clinical trial of liquor, and also immunological research of liquor (interleukins - 23, 12p40, and also GFAP). On the basis of the research IL-23, SILT-12p40, GFAP, the level of protein and a pleocytosis in liquor the predictive model of development of neurosyphilis in patients with syphilis without specific damage of nervous system is offered. The analysis of immunological changes in liquor of patients showed that the research of a number of cytokines and markers of damage of nervous tissue to liquor as the most specific and reliable, especially in the absence of clinical symptomatology from central nervous system can be an integral part of diagnostics of neurosyphilis also.


Assuntos
Proteína Glial Fibrilar Ácida/sangue , Subunidade p40 da Interleucina-12/sangue , Interleucina-23/sangue , Tecido Nervoso/patologia , Neurossífilis/diagnóstico , Humanos , Neurossífilis/imunologia
6.
Georgian Med News ; (278): 7-15, 2018 May.
Artigo em Inglês | MEDLINE | ID: mdl-29905537

RESUMO

The research is based on the results of the examination and treatment of 156 patients who received treatment for extended benign esophageal strictures after corrosive injuries in the department of diseases of the esophagus and the gastrointestinal tract of the State Institution "V. T. Zaitsev Institute of General and Urgent Surgery of NAMS of Ukraine" for the period from 2000 to 2016. Surgical treatment by the developed in our hospital technique performed in the patients of the main group and the classical methods of surgery were used in the patients of comparison group. The developed in our clinic method of one-step transhital esophagogastroplasty with formation of a single anastomosis on the neck in patients with extended benign esophageal strictures after corrosive injuries in the state of compensation and subcompensation can be considered as a method of choice. Adequate preoperative verification of the type of extended damage by the cicatricial process of the upper part of digestive tract and the impossibility of eating in a natural way in the acute postburn period, as well as significant nutritive disorders in patients, provide the basis for two-step surgical treatment. This approach involves formation of gastrostomy at the first step for the restoration of trophological status of the patient and esophagoplasty at the second step. The two-step surgical treatment of patients with extended benign esophageal strictures after corrosive injuries with the formation of contact gastrostomy at first step and the implementation of esophagogastroplasty on the second step promotes improvement of treatment outcomes and life quality of the operated patients.


Assuntos
Queimaduras Químicas/cirurgia , Estenose Esofágica/cirurgia , Esofagoplastia/métodos , Gastrostomia/métodos , Procedimentos de Cirurgia Plástica/métodos , Adulto , Anastomose Cirúrgica/métodos , Queimaduras Químicas/complicações , Queimaduras Químicas/diagnóstico por imagem , Queimaduras Químicas/patologia , Estenose Esofágica/diagnóstico por imagem , Estenose Esofágica/etiologia , Estenose Esofágica/patologia , Esôfago/diagnóstico por imagem , Esôfago/lesões , Esôfago/cirurgia , Feminino , Seguimentos , Humanos , Masculino , Pessoa de Meia-Idade , Radiografia , Índice de Gravidade de Doença , Resultado do Tratamento , Ucrânia
7.
J Am Chem Soc ; 131(14): 5257-63, 2009 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-19351205

RESUMO

Selection-amplification finds new RNA enzymes (ribozymes) among randomized RNAs with flanking unvaried sequences (primer complements). Precise removal of 3'-primer before reaction selected aminoacylation from PheAMP in three cycles, yielding active RNAs (k(cat) = 12-20 min(-1)) using only three conserved nucleotides, acting independently of divalent ions. This unusually simple RNA active site encouraged study of the reaction via molecular mechanics-based free energy minimization. On this basis, we suggest a chemical path for RNA-catalyzed transaminoacylation. Site modeling also predicted new features, L-stereoselectivity, 2'-regioselectivity, independence of amino acid side chain, and phosphorylated activating group, that were subsequently verified. The same selection also showed that RNA aminoacylation from adenylate is simpler than from CoA thioester, potentially rationalizing translational activation by adenylates. The simplicity of this active site suggests a general route to small ribozymes.


Assuntos
Nucleotídeos/química , RNA Catalítico/química , RNA Catalítico/metabolismo , Aminoacilação , Domínio Catalítico , Modelos Moleculares , Conformação de Ácido Nucleico , Nucleotídeos/metabolismo , Técnica de Seleção de Aptâmeros , Estereoisomerismo
8.
Soc Sci Med ; 41(4): 569-77, 1995 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-7481951

RESUMO

One hundred young new immigrant women from the former U.S.S.R. now living in Israel answered a detailed semi-open questionnaire regarding their knowledge, attitudes and behaviors in fertility and birth control issues. A collective family planning profile of these women is largely in line with that of the urban population of Slavonic U.S.S.R., combining early marriage, early and low fertility, the latter achieved by both abortion and contraception. Most respondents and their partners tried to prevent unwanted pregnancies, usually starting from traditional methods and switching over time to modern ones. An IUD remained most popular contraceptive among parous women, while use of the pill, very rare in the U.S.S.R., has almost doubled upon migration, mostly among younger women. Still, they kept some misleading ideas on the pros and cons of traditional versus modern methods, suggesting lack of adequate information also upon migration. Like their ex-compatriots, our women preferred to solve their birth control problems without external professional involvement. Contrary to the expected, free abortion ideology was not universally advocated by our respondents, and most were fully aware of abortion limitations in Israel. While rationally condemning abortion in both moral and health terms, most respondents still use it, this gap between beliefs and practice being indicative of their readiness to adopt efficient contraception. This switch occurs faster in women actively involved with host society via work or studies. Younger women were found to be more flexible and advanced in their family planning practices than were older ones, while almost no differences were related to education and origin within the U.S.S.R. This exploratory study suggests that any investment into promotion of healthy fertility control practices among new immigrants will be cost-effective in the near future.


Assuntos
Emigração e Imigração , Serviços de Planejamento Familiar , Conhecimentos, Atitudes e Prática em Saúde , Judeus/psicologia , Aborto Induzido/psicologia , Aculturação , Adulto , Características da Família , Feminino , Humanos , Israel , Masculino , Gravidez , U.R.S.S./etnologia , População Urbana
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