Tunneling Spectroscopy at Megabar Pressures: Determination of the Superconducting Gap in Sulfur.

The recent discovery of high-temperature, high-pressure superconductors, such as hydrides and nickelates, has opened exciting avenues in studying high-temperature superconductivity. The primary superconducting properties of these materials are well characterized by measuring various electrical and magnetic properties, despite the challenges posed by the high-pressure environment. Experimental microscopic insight into the pairing mechanism of these superconductors is even more challenging, due to the lack of direct probes of the superconducting gap structures at high pressure conditions.

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.

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

In the last few years, the superconducting transition temperature, T, 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.

Superconductivity up to 243 K in the yttrium-hydrogen system under high pressure.

The discovery of superconducting HS with a critical temperature T∼200 K opened a door to room temperature superconductivity and stimulated further extensive studies of hydrogen-rich compounds stabilized by high pressure. Here, we report a comprehensive study of the yttrium-hydrogen system with the highest predicted Ts among binary compounds and discuss the contradictions between different theoretical calculations and experimental data. We synthesized yttrium hydrides with the compositions of YH, YH, YH and YH in a diamond anvil cell and studied their crystal structures, electrical and magnetic transport properties, and isotopic effects.

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

The discovery of superconductivity above 250 K at high pressure in LaH and the prediction of overcoming the room temperature threshold for superconductivity in YH 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 YH under pressure up to 180 GPa. The combination of the experimental methods allowed us to implement a multiscale length study of YH: XAFS (short-range), Raman scattering (medium-range) and XRD (long-range).

Theoretical Treatment of Limitations Inherent in Simple 3D Stimuli: Triangles and the P3P Problem.

Understanding the visual stimulus in a psychophysical experiment, theoretically, is critical for controlling the experiment, for interpreting the empirical results of the experiment, and for discussing the mechanisms the visual system used to get these results. This fact encourages visual scientists to use "simple" visual stimuli in their experiments. A triangle is one of the simplest stimuli that has been used by psychophysicists to study 3D perception.

A Boosted Critical Temperature of 166 K in Superconducting D S Synthesized from Elemental Sulfur and Hydrogen.

The discovery of superconductivity in H S at 203 K marked an advance towards room-temperature superconductivity and demonstrated the potential of H-dominated compounds to possess a high critical temperature (T ). There have been numerous reports of the H-S system over the last five years, but important questions remain unanswered. It is crucial to verify whether the T was determined correctly for samples prepared from compressed H S, since they are inevitably contaminated with H-depleted byproducts.

A novel crystal form of metacetamol: the first example of a hydrated form.

We report the crystal structure and crystallization conditions of a first hydrated form of metacetamol (a hemihydrate), CHNO·0.5HO. It crystallizes from metacetamol-saturated 1:1 (v/v) water-ethanol solutions in a monoclinic structure (space group P2/n) and contains eight metacetamol and four water molecules per unit cell.

Superconducting phase diagram of HS under high magnetic fields.

The discovery of superconductivity at 260 K in hydrogen-rich compounds like LaH re-invigorated the quest for room temperature superconductivity. Here, we report the temperature dependence of the upper critical fields μH(T) of superconducting HS under a record-high combination of applied pressures up to 160 GPa and fields up to 65 T. We find that H(T) displays a linear dependence on temperature over an extended range as found in multigap or in strongly-coupled superconductors, thus deviating from conventional Werthamer, Helfand, and Hohenberg (WHH) formalism.

Superconductivity at 250 K in lanthanum hydride under high pressures.

With the discovery of superconductivity at 203 kelvin in HS, 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 atoms.

Cycluridine: A novel antiviral effective against flaviviruses.

This review describes the contemporary state of research for antivirals effective against flaviviruses, especially focusing on inhibitors of the pestivirus causative agent of bovine viral diarrhoea virus. We highlight cycluridine, an originally synthesized Mannich's base [a tetrahydro-2(1H)-pyrimidinones derivative], as a highly effective antiviral possessing a strong inhibitory effect on bovine viral diarrhoea virus replication. Cycluridine was active against replication of a wide variety of bovine viral diarrhoea virus strains in cell cultures.

[Radiation protection in medical research : Licensing requirement for the use of radiation and advice for the application procedure].

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.

A new solvate of furosemide with dimethylacetamide.

The loop diuretic furosemide is used widely in the treatment of congestive heart failure and edema, and is practically insoluble in water. The physicochemical and pharmacokinetic properties of drugs can be modified by preparing the drug in an appropriate solid-state form. A new solvate of furosemide with dimethylacetamide (DMA) {systematic name: 4-chloro-2-[(furan-2-yl)methylamino]-5-sulfamoylbenzoic acid N,N-dimethylacetamide disolvate}, CHClNOS·2CHNO, (I), is reported.

Isoenergetic Polymorphism: The Puzzle of Tolazamide as a Case Study.

In the present case study of tolazamide we illustrate how many seemingly contradictory results that have been obtained from experimental observations and theoretical calculations can finally start forming a consistent picture: a "puzzle put together". For many years, tolazamide was considered to have no polymorphs. This made this drug substance unique among the large family of sulfonylureas, which was known to be significantly more prone to polymorphism than many other organic compounds.

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(-)...

High-pressure crystallography of periodic and aperiodic crystals.

More than five decades have passed since the first single-crystal X-ray diffraction experiments at high pressure were performed. These studies were applied historically to geochemical processes occurring in the Earth and other planets, but high-pressure crystallography has spread across different fields of science including chemistry, physics, biology, materials science and pharmacy. With each passing year, high-pressure studies have become more precise and comprehensive because of the development of instrumentation and software, and the systems investigated have also become more complicated.

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.

Contribution of weak S-H · · · O hydrogen bonds to the side chain motions in D,L-homocysteine on cooling.

Sulfhydryl groups play an important role in the formation of native structures of proteins and their biological functions. In the present work, we report for the first time the crystal structure of D,L-homocysteine and the results of a detailed study of the dynamics of its sulfhydryl group on cooling by precise single-crystal X-ray diffraction combined with polarized Raman spectroscopy of oriented single crystals. Although the crystal structures of both D,L-cysteine and D,L-homocysteine are layered, hydrogen bonds formed by -SH groups differ.

Effect of pressure on methylated glycine derivatives: relative roles of hydrogen bonds and steric repulsion of methyl groups.

Infinite head-to-tail chains of zwitterions present in the crystals of all amino acids are known to be preserved even after structural phase transitions. In order to understand the role of the N-H..

Weak hydrogen bonds formed by thiol groups in N-acetyl-(L)-cysteine and their response to the crystal structure distortion on increasing pressure.

The effect of hydrostatic pressure on single crystals of N-acetyl-l-cysteine was followed at multiple pressure points from 10(-4) to 6.2 GPa with a pressure step of 0.2-0.

Dynamics and thermodynamics of crystalline polymorphs. 2. β-Glycine, analysis of variable-temperature atomic displacement parameters.

The molecular dynamics in the crystal and the thermodynamic functions of the β-polymorph of glycine have been determined from a combination of molecular translation-libration frequencies reflecting the temperature dependence of atomic displacement parameters (ADPs), with frequencies derived from ONIOM(DFT:PM3) calculations on a 15-molecule β-glycine cluster. ADPs have been obtained from variable-temperature diffraction data to 0.5 Å resolution collected with X-ray synchrotron (10-300 K) and sealed tube radiation (50-298 K).

Betaine 0.77-perhydrate 0.23-hydrate and common structural motifs in crystals of amino acid perhydrates.

The title compound, betaine 0.77-perhydrate 0.23-hydrate, (CH3)3N(+)CH2COO(-)·0.