Universal diamond edge Raman scale to 0.5 terapascal and implications for the metallization of hydrogen.

The recent progress in generating static pressures up to terapascal values opens opportunities for studying novel materials with unusual properties, such as metallization of hydrogen and high-temperature superconductivity. However, an evaluation of pressure above ~0.3 terapascal is a challenge. We report a universal high-pressure scale up to ~0.5 terapascal, which is based on the shift of the Raman edge of stressed diamond anvils correlated with the equation of state of Au and does not require an additional pressure sensor. According to the new scale, the pressure values are substantially lower by 20% at ~0.5 terapascal compared to the extrapolation of the existing scales. We compare the available data of H2 at the highest static pressures. We show that the onset of the proposed metallization of molecular hydrogen reported by different groups is consistent when corrected with the new scale and can be compared with various theoretical predictions.

Magnetic field screening in hydrogen-rich high-temperature superconductors.

In the last few years, the superconducting transition temperature, Tc, of hydrogen-rich compounds has increased dramatically, and is now approaching room temperature. However, the pressures at which these materials are stable exceed one million atmospheres and limit the number of available experimental studies. Superconductivity in hydrides has been primarily explored by electrical transport measurements, whereas magnetic properties, one of the most important characteristic of a superconductor, have not been satisfactory defined. Here, we develop SQUID magnetometry under extreme high-pressure conditions and report characteristic superconducting parameters for Im-3m-H3S and Fm-3m-LaH10-the representative members of two families of high-temperature superconducting hydrides. We determine a lower critical field Hc1 of ∼0.82 T and ∼0.55 T, and a London penetration depth λL of ∼20 nm and ∼30 nm in H3S and LaH10, respectively. The small values of λL indicate a high superfluid density in both hydrides. These compounds have the values of the Ginzburg-Landau parameter κ ∼12-20 and belong to the group of "moderate" type II superconductors, rather than being hard superconductors as would be intuitively expected from their high Tcs.

Local electronic structure rearrangements and strong anharmonicity in YH3 under pressures up to 180 GPa.

The discovery of superconductivity above 250 K at high pressure in LaH10 and the prediction of overcoming the room temperature threshold for superconductivity in YH10 urge for a better understanding of hydrogen interaction mechanisms with the heavy atom sublattice in metal hydrides under high pressure at the atomic scale. Here we use locally sensitive X-ray absorption fine structure spectroscopy (XAFS) to get insight into the nature of phase transitions and the rearrangements of local electronic and crystal structure in archetypal metal hydride YH3 under pressure up to 180 GPa. The combination of the experimental methods allowed us to implement a multiscale length study of YH3: XAFS (short-range), Raman scattering (medium-range) and XRD (long-range). XANES data evidence a strong effect of hydrogen on the density of 4d yttrium states that increases with pressure and EXAFS data evidence a strong anharmonicity, manifested as yttrium atom vibrations in a double-well potential.

Superconductivity at 250 K in lanthanum hydride under high pressures.

With the discovery1 of superconductivity at 203 kelvin in H3S, attention returned to conventional superconductors with properties that can be described by the Bardeen-Cooper-Schrieffer and the Migdal-Eliashberg theories. Although these theories predict the possibility of room-temperature superconductivity in metals that have certain favourable properties-such as lattice vibrations at high frequencies-they are not sufficient to guide the design or predict the properties of new superconducting materials. First-principles calculations based on density functional theory have enabled such predictions, and have suggested a new family of superconducting hydrides that possess a clathrate-like structure in which the host atom (calcium, yttrium, lanthanum) is at the centre of a cage formed by hydrogen atoms2-4. For LaH10 and YH10, the onset of superconductivity is predicted to occur at critical temperatures between 240 and 320 kelvin at megabar pressures3-6. Here we report superconductivity with a critical temperature of around 250 kelvin within the [Formula: see text] structure of LaH10 at a pressure of about 170 gigapascals. This is, to our knowledge, the highest critical temperature that has been confirmed so far in a superconducting material. Superconductivity was evidenced by the observation of zero resistance, an isotope effect, and a decrease in critical temperature under an external magnetic field, which suggested an upper critical magnetic field of about 136 tesla at zero temperature. The increase of around 50 kelvin compared with the previous highest critical temperature1 is an encouraging step towards the goal of achieving room-temperature superconductivity in the near future.

[Radiation protection in medical research : Licensing requirement for the use of radiation and advice for the application procedure]. / Strahlenschutz in der medizinischen Forschung : Genehmigungsbedürftigkeit von Strahlenanwendungen und Hinweise zum Antragsverfahren.

BACKGROUND: In Germany, persons who are to be exposed to radiation for medical research purposes are protected by a licensing requirement. However, there are considerable uncertainties on the part of the applicants as to whether licensing by the competent Federal Office for Radiation Protection is necessary, and regarding the choice of application procedure. AIM: The article provides explanatory notes and practical assistance for applicants and an outlook on the forthcoming new regulations concerning the law on radiation protection of persons in the field of medical research. MATERIALS AND METHODS: Questions and typical mistakes in the application process were identified and evaluated. RESULTS AND DISCUSSION: The qualified physicians involved in a study are responsible for deciding whether a license is required for the intended application of radiation. The decision can be guided by answering the key question whether the study participants would undergo the same exposures regarding type and extent if they had not taken part in the study. When physicians are still unsure about their decision, they can seek the advisory service provided by the professional medical societies. Certain groups of people are particularly protected through the prohibition or restriction of radiation exposure. A simplified licensing procedure is used for a proportion of diagnostic procedures involving radiation when all related requirements are met; otherwise, the regular licensing procedure should be used. The new radiation protection law, which will enter into force on the 31st of december 2018, provides a notification procedure in addition to deadlines for both the notification and the licensing procedures. In the article, the authors consider how eligible studies involving applications of radiation that are legally not admissible at present may be feasible in the future, while still ensuring a high protection level for study participants.

Unusual hydrogen bonding in L-cysteine hydrogen fluoride.

L-Cysteine hydrogen fluoride, or bis(L-cysteinium) difluoride-L-cysteine-hydrogen fluoride (1/1/1), 2C3H8NO2S(+)·2F(-)·C3H7NO2S·HF or L-Cys(+)(L-Cys···L-Cys(+))F(-)(F(-)...H-F), provides the first example of a structure with cations of the 'triglycine sulfate' type, i.e. A(+)(A···A(+)) (where A and A(+) are the zwitterionic and cationic states of an amino acid, respectively), without a doubly charged counter-ion. The salt crystallizes in the monoclinic system with the space group P2(1). The dimeric (L-Cys···L-Cys(+)) cation and the dimeric (F(-)···H-F) anion are formed via strong O-H···O or F-H···F hydrogen bonds, respectively, with very short O···O [2.4438 (19) Å] and F···F distances [2.2676 (17) Å]. The F···F distance is significantly shorter than in solid hydrogen fluoride. Additionally, there is another very short hydrogen bond, of O-H···F type, formed by a L-cysteinium cation and a fluoride ion. The corresponding O···F distance of 2.3412 (19) Šseems to be the shortest among O-H···F and F-H···O hydrogen bonds known to date. The single-crystal X-ray diffraction study was complemented by IR spectroscopy. Of special interest was the spectral region of vibrations related to the above-mentioned hydrogen bonds.

Sarcosine and betaine crystals upon cooling: structural motifs unstable at high pressure become stable at low temperatures.

The crystal structures of N-methyl derivatives of the simplest amino acid glycine, namely sarcosine (C3H7NO2) and betaine (C5H11NO2), were studied upon cooling by single-crystal X-ray diffraction and single-crystal polarized Raman spectroscopy. The effects of decreasing temperature and increasing hydrostatic pressure on the crystal structures were compared. In particular, we have studied the behavior upon cooling of those structural motifs in the crystals, which are involved in structural rearrangement during pressure-induced phase transitions. In contrast to their high sensitivity to hydrostatic compression, the crystals of both sarcosine and betaine are stable to cooling down to 5 K. Similarly to most α-amino acids, the crystal structures of the two compounds are most rigid upon cooling in the direction of the main structural motif, namely head-to-tail chains (linked via the strongest N-H···O hydrogen bonds and dipole-dipole interactions in the case of sarcosine, or exclusively by dipole-dipole interactions in the case of betaine). The anisotropy of linear strain in betaine does not differ much upon cooling and on hydrostatic compression, whereas this is not the case for sarcosine. Although the interactions between certain structural motifs in sarcosine and betaine weaken as a result of phase transitions induced by pressure, the same interactions strengthen when volume reduction results from cooling.

[Changes in the "medical research" licensing procedure under the German Radiation Protection Ordinance]. / Neuerungen im Genehmigungsverfahren "Medizinische Forschung" gemäß Röntgen- und Strahlenschutzverordnung.

This publication outlines the "medical research" licensing procedure as specified in the amendment of the German Radiation Protection Ordinance of November 1, 2011. The general licensing requirements for the use of radiation have not been changed by the amendment. Three so-called use restrictions (i. e., dose limits of 10 mSv and 20 mSv, age limit of 50 years) have been modified. They will only apply to healthy volunteers in the future. In addition, there are considerable simplifications with respect to applications and licensing procedures of the Federal Office for Radiation Protection (Bundesamt für Strahlenschutz, BfS) regarding the use of radiation in the newly introduced "accompanying diagnostics" ("Begleitdiagnostik") case group. The newly established, independent panel of experts at the German Radiological Society (Deutsche Röntgengesellschaft, DRG) may provide essential support to principal investigators, qualified physicians and sponsors for differentiating between "medical research" and "health care", the latter not being subject to licensing. An expert statement will be issued by the DRG within four weeks of an inquiry. This consulting service is subject to confidentiality, and is free of charge for inquirers and without any commitment.

[Nuclear-medical irradiation during pregnancy. Risk assessment for the offspring]. / Nuklearmedizinische Strahlenexpositionen während der Schwangerschaft. Risikoabschätzungen für die Leibesfrucht.

UNLABELLED: AIM To estimate and evaluate the risks for the offspring due to the administration of radiopharmaceuticals to women during the first pregnancy weeks after conception (weeks p.c.). METHODS: The in-utero exposition of the embryo due to diagnostic nuclear medicine procedures, for which diagnostic reference levels (DRL) are specified, as well as due to radio iodine therapy (RIT) was determined. To this end, it is assumed that the activity of the diagnostic radiopharmaceuticals administered to the mother corresponds with the DRL and amounts to 600 MBq or 4 GBq 131I for RIT of benign or malignant thyroid disease, respectively. Based on these data, the radiation risk for the offspring was assessed and compared with the spontaneous risks (R0). RESULTS: The dose for the offspring does not exceed 7.8 mSv for the diagnostic procedures considered, resulting in an excess risk for the offspring of less than 0.12% (R0 approximately 25%) to die from cancer during life, of less than 0.07% (R0 approximately 0.2%) to develop cancer up to the age of 15 years, and of less than 0.16% (R0 approximately 2%) for hereditary effects. RIT during the first 8 weeks p.c. results in doses for the offspring of about 100-460 mSv, resulting in an excess risk for malformations of the child of 3.4%-22% (R0 approximately 6%). CONCLUSIONS: The risk of stochastic radiation effects for the offspring due to a diagnostic nuclear medicine procedure of the mother during the first 8 weeks p.c. is--compared with the spontaneous risks--very small; deterministic effects are unlikely. In contrast, deterministic effects for the offspring may occur following RIT. In order to decide on a possibly indicated abortion after RIT, an individual risk assessment is mandatory.

[FDG-PET/CT in oncology. German Guideline]. / FDG-PET/CT in der Onkologie. Leitlinie.

FDG-PET/CT examinations combine metabolic and morphologic imaging within an integrated procedure. Over the past decade PET/CT imaging has gained wide clinical acceptance in the field of oncology. This FDG-PET/CT guideline focuses on indications, data acquisition and processing as well as documentation of FDG-PET/CT examinations in oncologic patients within a clinical and social context specific to Germany. Background information and definitions are followed by examples of clinical and research applications of FDG-PET/CT. Furthermore, protocols for CT scanning (low dose and contrast-enhanced CT) and PET emission imaging are discussed. Documentation and reporting of examinations are specified. Image interpretation criteria and sources of errors are discussed. Quality control for FDG and PET/CT-systems, qualification requirements of personnel as well as legal aspects are presented.

[Establishment and application of diagnostic reference levels for nuclear medicine procedures in Germany]. / Festlegung und Anwendung diagnostischer Referenzwerte für nuklearmedizinische Untersuchungen in Deutschland.

UNLABELLED: Diagnostic reference levels (DRL) were introduced in Germany by a publication in the Bundesanzeiger Nr. 143 from August 5, 2003. Thereby a recommendation of the International Commission on Radiological Protection (ICRP) from 1996 and a demand by the EU Guideline 97/43/EURATOM from 1997 is converted into national law. AIM of this paper is to acquaint with and to justify the determined DRL as well as to provide information on the practical use of the concept of the DRL. MATERIAL AND METHOD: DRL were established by experts on the basis of a national survey conducted in hospitals and private practices as well as of national and international recommendations and published by the Federal Office for Radiation Protection. Besides the data basis the dosimetric principles are described for the estimation of the effective doses of the various examinations. RESULTS: DRL were established for 10 frequent and dose-relevant examinations constituting more than 80% of all nuclear medicine examinations currently performed in Germany. For some examinations two different DRL were given to take into account clinical conditions. For paediatric examinations fractions of the activities to be administered to adults are given dependent on the body weight. DISCUSSION: The published DRL are in agreement with the majority of national and international recommendations and with the present practice of nuclear medicine examinations in Germany. They are related to average activities for groups of patients with standard sizes and, moreover, to typical examinations with current standard equipment. It is planned to check and to reconsider the DRL about every 2-3 years.

[Application of radioactive substances in nuclear medicine research: current trends and radiation exposure of study subjects]. / Anwendung radioaktiver Stoffe in der nuklearmedizinischen Forschung: aktuelle Trends und Strahlenexposition der Probanden.

AIM: Analysis of the application of radioactive substances in research in the field of nuclear medicine in human beings and of the resulting radiation exposure to study subjects. METHODS: Assessment of applications for approval submitted in accordance with Paragraph 41 of the Radiation Protection Ordinance, evaluated by the Federal Office for Radiation Protection together with the Federal Institute for Pharmaceuticals and Medical Products, within the period from 1997 to 1999. RESULTS: The focus of the studies on the diagnostic application of radioactive substances in medicine evaluated has, since 1998, shifted from oncological to neurological and psychological aspects, while, at the same time, the number of PET studies increased constantly. The proportion of healthy study subjects included in the diagnostic studies increased from 7 to 22%. The number of therapeutic applications of radioactive substances has, since 1997, undergone a three-fold increase, and in the process of this, the focus of attention lay within the area of radioimmuno-therapy and endovascular brachytherapy. The effective dose was, among up to 49% of the investigated healthy study subjects higher than 5 mSv, and among up to 6% of these subjects was at levels of over 20 mSv. Up to 22% of the patients received, within the scope of diagnostic studies, an effective dose of between 20 and 50 mSv. An exceeding of the 50 mSv limit occurred among up to 3% of the patients. CONCLUSIONS: In spite of the increasing numbers of PET applications, conventional nuclear medicine has maintained its importance in the field of medical research. Further developments in the areas of radiochemistry and molecular biology led to an increase in the importance of radio-immuno therapy. The evaluation of new radiopharmaceuticals and the extension of basic biomedical research, resulted in an increase in the proportion of healthy study subjects included in the studies. The radiation exposure among subjects resulting directly from the studies showed, for the period of evaluation, an overall trend towards reduction.

[Cytochemical study of acid naphthyl acetate esterase in the lymphocytes of healthy and bovine leukemia virus-infected cows]. / Tsitokhimichno prouchvane na kiselata naftilatsetatna esteraza v limfotsitite na zdravi i infektirani s virusa na govezhdata levkoza kravi.

A modified cytochemical technique was employed to investigate the unspecific acid naphthylacetate esterase of lymphocytes in the peripheral blood of a total of 64 clinically normal cows, having negative serologic and hematologic reaction for leukosis and of 42 cows with severalfold, well-manifested positive serologic response for the presence of the bovine leukosis virus with no changes in the hematologic data. With the normal animals an average of 6.86 per cent of the peripheral lymphocytes were found to be active--in the form of large dark-brown to dark red-brown granules--and such cells were considered to be T mu mature lymphocytes, while in 53.3 per cent of the cells activity was manifested in the form of tiny powder-like granules, and these were believed to be the Ty lymphocytes. Generally, 63.2 per cent were T-lymphocytes; the remaining 36.9 per cent of the cells had no activity typical for acid esterase, and these were considered to be B-lymphocytes. The study of cows with manifested agar gel immunodiffusion reaction for the presence of the bovine leukosis virus, with no lymphocytosis, revealed that there was a reliable rise of the T mu-lymphocytes up to 23.1 per cent, on an average, of the Ty-lymphocytes up to 69.2 per cent, while the percent of the B-lymphocytes dropped to 7.77 per cent, on an average.