Antiferromagnetic excitonic insulator state in Sr3Ir2O7.

Excitonic insulators are usually considered to form via the condensation of a soft charge mode of bound electron-hole pairs. This, however, presumes that the soft exciton is of spin-singlet character. Early theoretical considerations have also predicted a very distinct scenario, in which the condensation of magnetic excitons results in an antiferromagnetic excitonic insulator state. Here we report resonant inelastic x-ray scattering (RIXS) measurements of Sr3Ir2O7. By isolating the longitudinal component of the spectra, we identify a magnetic mode that is well-defined at the magnetic and structural Brillouin zone centers, but which merges with the electronic continuum in between these high symmetry points and which decays upon heating concurrent with a decrease in the material's resistivity. We show that a bilayer Hubbard model, in which electron-hole pairs are bound by exchange interactions, consistently explains all the electronic and magnetic properties of Sr3Ir2O7 indicating that this material is a realization of the long-predicted antiferromagnetic excitonic insulator phase.

Bovine serum albumin nanoparticles containing amphotericin B were effective in treating murine cutaneous leishmaniasis and reduced the drug toxicity.

Cutaneous leishmaniasis is the most common form of leishmaniasis and the available chemotherapy causes serious side effects, justifying the search for new therapies. This study investigated the antileishmanial activity of bovine serum albumin (BSA) nanoparticles containing amphotericin B (AmB) against Leishmania amazonensis. The antiproliferative activity against promastigotes and amastigotes was assessed and the cytotoxicity was determined and compared to commercial AmB-deoxycholate (AmB-D). In vivo antileishmania activity was evaluated in murine cutaneous leishmaniasis model. BSA nanoparticles showed spherical shape, mean size about 180 nm, zeta potential of ≈ -45 mV and AmB encapsulation efficiency >95%. AmB-D was effective in promastigote and amastigote forms, while AmB-loaded BSA nanoparticles were more effective against amastigotes than promastigotes. AmB-D was more effective than AmB-loaded BSA nanoparticles in both forms, however, the lowest cytotoxicity against macrophages was achieved by AmB-nanoparticles. BALB/c mice treated with AmB-D or AmB-loaded BSA nanoparticles showed a significant decrease in the lesion thickness at the infected footpad. Histopathological analysis after 3 weeks of treatment revealed AmB-D-related toxicity in heart, spleen, lung, liver and kidneys, while treatment with AmB-loaded BSA nanoparticles did not reveal tissue toxicity. The antileishmanial efficacy and the reduced toxicity become BSA nanoparticles containing AmB a potential candidate for treating cutaneous leishmaniasis.

Carqueja (Baccharis trimera): utilização terapêutica e biossíntese / Broom (Baccharis trimera): therapeutic use and biosynthesis

A utilização de plantas medicinais no tratamento e cura de enfermidades é um recurso terapêutico muito antigo e talvez o único adotado em muitas comunidades e grupos étnicos. A família Asteraceae concentra grande número de espécies com potencial terapêutico, algumas das quais do gênero Baccharis, utilizadas na medicina popular e também na produção de fitoterápicos. Estudos relatam que a principal indicação terapêutica mencionada para estas espécies estão relacionadas com ações sobre o trato gastrintestinal. A partir de pesquisa bibliográfica, foram identificadas as características morfológicas da carqueja, bem como, as propriedades terapêuticas cientificamente comprovadas, biossíntese dos principais metabólitos secundários, e possíveis interações medicamentosas.

The use of medicinal plants to treat and cure diseases is a very old therapeutic resource and perhaps the only one adopted in many communities and ethnic groups. The Asteraceae family concentrates a great number of species with therapeutic potential, some of which belong to the Baccharis genus and have been used in folk medicine and herbal medicine production. Studies have reported that the main therapeutic indication for these species is related to actions on the gastrointestinal tract. From literature searches, the morphological characteristics of broom, its scientifically proven therapeutic properties, as well as biosynthesis of secondary metabolites and possible drug interactions were identified.

Windowless transition between atmospheric pressure and high vacuum via differential pumping for synchrotron radiation applications.

A differential pump assembly is introduced which can provide a windowless transition between the full atmospheric pressure of an in-air sample environment and the high-vacuum region of a synchrotron radiation beamline, while providing a clear aperture of approximately 1 mm to pass through the X-ray beam from a modern third-generation synchrotron radiation source. This novel pump assembly is meant to be used as a substitute for an exit vacuum window on synchrotron beamlines, where the existence of such a window would negatively impact the coherent nature of the X-ray beam or would introduce parasitic scattering, distorting weak scattering signals from samples under study. It is found that the length of beam pipe necessary to reduce atmospheric pressure to below 10 mbar is only about 130 mm, making the expected photon transmission for hard X-rays through this pipe competitive with that of a regular Be beamline window. This result is due to turbulent flow dominating the first pumping stage, providing a mechanism of strong gas conductance limitation, which is further enhanced by introducing artificial surface roughness in the pipe. Successive reduction of pressure through the transitional flow regime into the high-vacuum region is accomplished over a length of several meters, using beam pipes of increasing diameter. While the pump assembly has not been tested with X-rays, possible applications are discussed in the context of coherent and small-angle scattering.

A 2 m inelastic X-ray scattering spectrometer at CMC-XOR, Advanced Photon Source.

The design and commissioning of an inelastic X-ray scattering instrument at CMC-XOR at the Advanced Photon Source is reported. The instrument features a 2 m vertical-scattering arm with a novel counterweight design to reduce the twisting moment as the arm is moved in the scattering plane. A Ge(733) spherical analyzer was fabricated and an overall resolution of 118 meV (FWHM) was obtained with a Si(444) monochromator and a Si(111) pre-monochromator. Early results from a representative cuprate, La(2)CuO(4), are reported.