Distortions of C-60(4-) studied by infrared spectroscopy

The Jahn-Teller effect plays a crucial role in the explanation of the insulating character of A(4)C(60) (A = K, Rb, Cs). To detect possible phase transitions arising from the interplay between the molecular Jahn-Teller distortion and the distorting potential field of the counterions, we measured the mid-IR spectra of A(4)C(60) compounds in the temperature range 90 - 300 K and found significant spectral changes with temperature in all three compounds. We also compare these spectra to that of Na(4)C(60) in its room-temperature polymeric phase, where the distortion is more pronounced and evident from the structure

Ordered low-temperature structure in K4C60 detected by infrared spectroscopy

Infrared spectra of a K4C60 single-phase thin film have been measured between room temperature and 20 K. At low temperatures, the two high-frequency T1u modes appear as triplets, indicating a static D2h crystal-field stabilized Jahn-Teller distortion of the (C60)4- anions. The T1u(4) mode changes into the known doublet above 250 K, a pattern which could have three origins: a dynamic Jahn-Teller effect, static disorder between "staggered" anions, or a phase transition from an orientationally-ordered phase to one where molecular motion is significant.Comment: 4 pages, 2 figures submitted to Phys. Rev.

Structure and properties of the stable two-dimensional conducting polymer Mg5C60

We present a study on the structural, spectroscopic, conducting, and magnetic properties of Mg5C60, which is a two-dimensional (2D) fulleride polymer. The polymer phase is stable up to the exceptionally high temperature of 823 K. The infrared and Raman studies suggest the formation of single bonds between the fulleride ions and possibly Mg-C-60 covalent bonds. Mg5C60 is a metal at ambient temperature, as shown by electron spin resonance and microwave conductivity measurements. The smooth transition from a metallic to a paramagnetic insulator state below 200 K is attributed to Anderson localization driven by structural disorder

Giant microwave absorption in fine powders of superconductors

Enhanced microwave absorption, larger than that in the normal state, is observed in fine grains of type-II superconductors (MgB$_2$ and K$_3$C$_{60}$) for magnetic fields as small as a few $\%$ of the upper critical field. The effect is predicted by the theory of vortex motion in type-II superconductors, however its direct observation has been elusive due to skin-depth limitations; conventional microwave absorption studies employ larger samples where the microwave magnetic field exclusion significantly lowers the absorption. We show that the enhancement is observable in grains smaller than the penetration depth. A quantitative analysis on K$_3$C$_{60}$ in the framework of the Coffey--Clem (CC) theory explains well the temperature dependence of the microwave absorption and also allows to determine the vortex pinning force constant

Inner tegument protein pUL37 of herpes simplex virus type 1 is involved in directing capsids to the trans-Golgi network for envelopment

Secondary envelopment of herpes simplex virus type 1 has been demonstrated as taking place at the trans-Golgi network (TGN). The inner tegument proteins pUL36 and pUL37 and the envelope glycoproteins gD and gE are known to be important for secondary envelopment. We compared the cellular localizations of capsids from a virus mutant lacking the UL37 gene with those of a virus mutant lacking the genes encoding gD and gE. Although wild-type capsids accumulated at the TGN, capsids of the pUL37− mutant were distributed throughout the cytoplasm and showed no association with TGN-derived vesicles. This was in contrast to capsids from a gD−gE− mutant, which accumulated in the vicinity of TGN vesicles, but did not colocalize with them, suggesting that they were transported to the TGN but were unable to undergo envelopment. We conclude that the inner tegument protein pUL37 is required for directing capsids to the TGN, where secondary envelopment occurs

A prospective randomized trial of tacrolimus and prednisone versus tacrolimus, prednisone and mycophenolate mofetil in primary adult liver transplantation: A single center report

Background. Tacrolimus (TAC) and mycophenolate mofetil (MMF) are currently approved immunosuppressants for prevention of rejection in liver transplantation (LTx). They have different modes of action and toxicity profiles, but the efficacy and safety of MMF in primary liver transplantation with TAC has not been determined. Methods. An Institutional Review Board-approved, open-label, single-center, prospective randomized trial was initiated to study the efficacy and toxicity of TAC and steroids (double-drug therapy (D)) versus TAC, steroids, and MMF (triple-drug therapy (T)) in primary adult LTx recipients. Both groups of patients were started on the same doses of TAC and steroids. Patients randomized to T also received 1 gm MMF twice a day. Results. Between August 1995 and May 1998, 350 patients were enrolled at a single center-175 in the D and 175 in the T groups. All patients were followed until May 1998, with a mean follow-up of 33.8±9.1 months. Using an intention-to-treat analysis, the 1-, 2-, 3-, and 4-year patient survival was 85.1%, 81.6%, 78.6%, and 75.8%, respectively, for D and 87.4%, 85.4%, 81.3%, and 79.9%, respectively, for T. The 4-year graft survival was 70% for D and 72.1% for T. Although the rate of acute rejection in the first 3 months was significantly lower for T than for D (28% for triple vs. 38.9% for double, P=0.03), the overall rate of rejection for T at the end of 1 year was not significantly lower than for the D (38.9% triple vs. 45.2% double). The median time to the first episode of rejection was 14 days for D versus 24 days for T (P=0.008). During the study period, 38 of 175 patients in D received MMF to control ongoing acute rejection, nephrotoxicity, and/or neurotoxicity. On the other hand, 103 patients in the T discontinued MMF for infection, myelosuppression, and/or gastrointestinal disturbances. The need for corticosteroids was less after 6 months for T and the perioperative need for dialysis was lower with use of MMF. Conclusion. This final report confirms similar patient survival and graft survival up to 4 years with a trend towards fewer episodes of rejection, lower need for steroids, and better perioperative renal function. However, the complex nature of LTx patients and their posttransplantation course prevents the routine application of MMF

High-spin states in 212Po above the α-decaying (18+) isomer

The nucleus Po has been produced through the fragmentation of a U primary beam at 1 GeV/nucleon at GSI, separated with the FRagment Separator, FRS, and studied via isomer γ-decay spectroscopy with the RISING setup. Two delayed previously unknown γ rays have been observed. One has been attributed to the E3 decay of a 21 isomeric state feeding the α-emitting 45-s (18) high-spin isomer. The other γ-ray line has been assigned to the decay of a higher-lying 23 metastable state. These are the first observations of high-spin states above the Po (18) isomer, by virtue of the selectivity obtained via ion-by-ion identification of U fragmentation products. Comparison with shell-model calculations points to shortfalls in the nuclear interactions involving high-j proton and neutron orbitals, to which the region around Z∼100 is sensitive.This work was partially supported by the Ministry of Science, and Generalitat Valenciana, Spain, under the Grants SEV-2014-0398, FPA2017-84756-C4, PID2019-104714GB-C21, PROMETEO/2019/005 and by the EU FEDER funds. The support of the UK STFC, of the Swedish Research Council under Contract No. 2008-4240 and No. 2016-3969 and of the DFG (EXC 153) is also acknowledged. The experimental activity has been partially supported by the EU under the FP6-Integrated Infras-tructure Initiative EURONS, Contract No. RII3-CT-2004-506065 and FP7-Integrated Infrastructure Initiative ENSAR, Grant No. 262010