THz and IR spectroscopy of endofullerene H₂O@C₆₀

Terahertz time-domain and infrared Fourier-transform spectroscopy techniques are used to investigate the properties of H2O@C60 endofullerene in 6 K – 300 K temperature interval. A number of absorption lines associated with rotational transitions of water molecule entrapped inside C60 cages are observed and assigned. Fitting the resonances with Lorenzian lineshapes allowed us to obtain temperature dependencies of absorption lines parameters – frequency, strength and damping

Hertz-to-terahertz dielectric response of nanoconfined water molecules

Broad-band dielectric spectroscopy, heat capacity measurements and molecular dynamic simulations are applied to study excitations of interacting electric dipoles spatially arranged in a network with an inter-dipole distance of 5-10 A. The dipoles with magnitude of 1.85 Debye are represented by single H2O molecules located in voids (0.5 nm size) formed by ions of the crystal lattice of cordierite. We discover emergence of nontrivial disordered paraelectric phase of dipolar system with signs of phase transition below 3 K.Comment: 3 pages, 4 figure

Rotational coherence of encapsulated ortho and para water in fullerene-C₆₀ revealed by time-domain terahertz spectroscopy

We resolve the real-time coherent rotational motion of isolated water molecules encapsulated in fullerene-C60 cages by time-domain terahertz (THz) spectroscopy. We employ single-cycle THz pulses to excite the low-frequency rotational motion of water and measure the subsequent coherent emission of electromagnetic waves by water molecules. At temperatures below ~ 100 K, C60 lattice vibrational damping is mitigated and the quantum dynamics of confined water are resolved with a markedly long rotational coherence, extended beyond 10 ps. The observed rotational transitions agree well with low-frequency rotational dynamics of single water molecules in the gas phase. However, some additional spectral features with their major contribution at ~2.26 THz are also observed which may indicate interaction between water rotation and the C60 lattice phonons. We also resolve the real-time change of the emission pattern of water after a sudden cooling to 4 K, signifying the conversion of ortho-water to para-water over the course of 10s hours. The observed long coherent rotational dynamics of isolated water molecules confined in C60 makes this system an attractive candidate for future quantum technology

Unique interplay between superconducting and ferromagnetic orders in EuRbFe4As4

© 2018 American Physical Society. Transport, magnetic, and optical investigations on EuRbFe4As4 single crystals evidence that the ferromagnetic ordering of the Eu2+ magnetic moments at Tm=15 K, below the superconducting transition (Tc=36 K), affects superconductivity in a weak but intriguing way. Upon cooling below Tm, the zero resistance state is preserved and the diamagnetic response is only slightly affected by the emerging ferromagnetism; a perfect diamagnetism is recovered at low temperatures. The infrared conductivity is strongly suppressed in the far-infrared region below Tc, associated with the opening of a complete superconducting gap at 2Δ=10 meV. A gap smaller than the weak-coupling limit suggests strong orbital effects or, within a multiband superconductivity scenario, the existence of a larger yet unrevealed gap

THE COMPLEX TREATMENT OF THE PATIENT WITH MULTIPLE SPINE AND SPINAL CORD MALFORMATIONS

Clinical case of the patient with the congenital deformation of thoracic and lumbar parts of the spine due to multiple congenital anomalies of vertebrae (disturbance of formation, fusion and segmentation), a terminale filum lipoma at the level of L5, tethered cord, rightside lower leg monoparesis. Multistage surgical treatment was performed: removing of intracanal deformity, correction and stabilization of the deformity at the thoracic and lumbar part of the spine. Patient was followed up during 2,5 years after the last step of the surgical operation. No evidence of recurrence or neurological deterioration were observed

Effect of hydrostatic pressure on the quantum paraelectric state of dipolar coupled water molecular network

We measure the real part ε^{′} of the dielectric permittivity of beryl crystals with heavy water molecules D_{2}O confined in nanosized cages formed by an ionic crystal lattice. The experiments are performed at a frequency of 1 MHz in the temperature interval from 300 down to 4 K under different hydrostatic pressures up to P=6.3 GPa. At high temperatures, a Curie-Weiss-like increase of ε^{′}(T) is observed upon cooling. Application of pressure leads to flattening of ε^{′}(T) at low temperatures due to quantum effects, i.e., tunneling of deuterium atoms in the hexagonal localizing potential. Analyzing the temperature behavior of ε^{′} with the Barrett expression allows us to obtain pressure dependencies of the quantum temperature T_{1}, the Curie-Weiss temperature T_{C}, and the Barrett constant C. The increase of T_{1} observed up to 4 GPa is associated with an enhanced azimuthal tunneling of the confined water molecules through the barriers of the potential. For P>4 GPa, T_{1}(P) levels off since the barriers disappear. Any further pressure increase does not affect the tunneling rate because of the absence of a barrier. The behavior is modeled by solving the Schrödinger equation for the water molecule in the azimuthal potential numerically. Small negative values of T_{C}≈−10 K obtained for P<4 GPa indicate the antiferroelectric ordering tendency of the water dipoles localized in the crystalline nanochannels. For higher pressure, a strong decrease of T_{C} toward negative values is observed that would correspond to the enhanced interdipole coupling strength, which is however hard to explain in the present case, and thus calls for additional theoretical and experimental studies

THz and IR spectroscopy of H₂O@C₆₀ endofullerene

Time-domain terahertz and Fourier-transform infrared spectroscopy techniques are employed for investigating of the low-frequency dynamics of H2O@C60 endofullerene at temperatures 6–300 K. A number of absorption lines associated with rotational transitions of water molecules entrapped inside C60 cage are observed and assigned. Fitting absorption lines with Lorentzians allowed us to obtain the temperature dependences of the lines’ parameters – frequency position, strength and damping

SURGICAL TREATMENT OF CHILDREN WITH CONGENITAL LUMBAR SCOLIOSIS: COMPLETE OR PARTIAL RESECTION OF MALFORMED VERTEBRAE?

The purpose of the study – to compare the effectiveness of surgical correction of spine lumbar congenital deformity by complete or partial resection of the abnormal vertebra in children.Material and methods. 68 children with isolated congenital malformation of the lumbar area of the spine were evaluated both clinically and instrumentally. Age of the patients was 6 months — 16 years 2 months (mean — 4 years 5 months). There were 41 female and 27 male patients. Patients were divided in two groups depending on the volume of the surgery. First group (n = 52) consisted of patients treated with complete hemivertebrae resection. Second group (n = 16) consisted of patients treated with partial resection of the malformed vertebrae.Results. After the surgery in the 1st group scoliotic curve was 0 to 21° and kyphotic curve was from -33 to 9°. 9 years post-op scoliotic and kyphotic curves were 0 to 22° and -31 to 10° respectively. In the 2nd group scoliotic curve was 3 to 27° and kyphotic curve was from -30 to 12°. 9 years post-op scoliotic and kyphotic curves were 7 to 41° and -26 to 8° respectively. Significant differences in the amount of scoliotic curve correction were revealed between the groups: in the 1st group mean Cobb angle for the scoliotic curve after surgery was 3,3° (correction — 94%), in the 2nd group — 13,6° (correction — 80%) (p&lt;0,05). Mean Cobb angle for the scoliotic curve in the long-term period was 5° (correction — 92%) for the 1st group wich was significantly lower (p&lt;0,05) comparing to the 2nd group (mean Cobb angle 18,3° correction — 62%).Conclusion. Our data showed higher efficacy of the complete resection of the hemivertebrae comparing to its partial resection in pediatric patients with isolated malformation in the lumbar spine. Complete removal of the vertebrae body, its growth plates and disks allowed to achieve radical correction of the deformity and to perform short fusion of the adjacent segments which was crucial for further normal growth and development of the child’s spine with saving the results in the long-term period. Thus complete resection of the malformed vertebrae with radical correction and short segment fusion is the most appropriate option in surgical treatment of pediatric patient of any age with isolated vertebrae malformation in the lumbar spine