42 research outputs found
Biochemical and Ultrastructural Changes in the Hepatopancreas of Bellamya aeruginosa (Gastropoda) Fed with Toxic Cyanobacteria
This study was conducted to investigate ultrastructural alterations and biochemical responses in the hepatopancreas of the freshwater snail Bellamya aeruginosa after exposure to two treatments: toxic cyanobacterium (Microcystis aeruginosa) and toxic cyanobacterial cells mixed with a non-toxic green alga (Scendesmus quadricauda) for a period of 15 days of intoxication, followed by a 15-day detoxification period. The toxic algal suspension induced a very pronounced increase of the activities of acid phosphatases, alkaline phosphatases and glutathione S-transferases (ACP, ALP and GST) in the liver at the later stage of intoxication. During the depuration, enzymatic activity tended to return to the levels close to those in the control. The activity of GST displayed the most pronounced response among different algal suspensions. Severe cytoplasmic vacuolization, condensation and deformation of nucleus, dilation and myeloid-like in mitochondria, disruption of rough endoplasmic reticulum, proliferation of lysosome, telolysosomes and apoptotic body were observed in the tissues. All cellular organelles began recovery after the snails were transferred to the S. quadricauda. The occurrence of a large amount of activated lysosomes and heterolysosomes and augment in activity of detoxification enzyme GST might be an adaptive mechanism to eliminate or lessen cell damage caused by hepatotoxicity to B. aeruginosa
Metallic surface states in a correlated d-electron topological Kondo insulator candidate FeSb2
The resistance of a conventional insulator diverges as temperature approaches
zero. The peculiar low temperature resistivity saturation in the 4f Kondo
insulator (KI) SmB6 has spurred proposals of a correlation-driven topological
Kondo insulator (TKI) with exotic ground states. However, the scarcity of model
TKI material families leaves difficulties in disentangling key ingredients from
irrelevant details. Here we use angle-resolved photoemission spectroscopy
(ARPES) to study FeSb2, a correlated d-electron KI candidate that also exhibits
a low temperature resistivity saturation. On the (010) surface, we find a rich
assemblage of metallic states with two-dimensional dispersion. Measurements of
the bulk band structure reveal band renormalization, a large
temperature-dependent band shift, and flat spectral features along certain high
symmetry directions, providing spectroscopic evidence for strong correlations.
Our observations suggest that exotic insulating states resembling those in SmB6
and YbB12 may also exist in systems with d instead of f electrons
Emergence of Quasiparticles in a Doped Mott Insulator
How a Mott insulator develops into a weakly coupled metal upon doping is a
central question to understanding various emergent correlated phenomena. To
analyze this evolution and its connection to the high- cuprates, we study
the single-particle spectrum for the doped Hubbard model using cluster
perturbation theory on superclusters. Starting from extremely low doping, we
identify a heavily renormalized quasiparticle dispersion that immediately
develops across the Fermi level, and a weakening polaronic side band at higher
binding energy. The quasiparticle spectral weight roughly grows at twice the
rate of doping in the low doping regime, but this rate is halved at optimal
doping. In the heavily doped regime, we find both strong electron-hole
asymmetry and a persistent presence of Mott spectral features. Finally, we
discuss the applicability of the single-band Hubbard model to describe the
evolution of nodal spectra measured by angle-resolved photoemission
spectroscopy (ARPES) on the single-layer cuprate LaSrCuO (). This work benchmarks the predictive power of the Hubbard
model for electronic properties of high- cuprates.Comment: 7 pages, 5 figure