Comprehensive defect suppression in perovskite nanocrystals for high-efficiency light-emitting diodes

Electroluminescence efficiencies of metal halide perovskite nanocrystals (PNCs) are limited by a lack of material strategies that can both suppress the formation of defects and enhance the charge carrier confinement. Here we report a one-dopant alloying strategy that generates smaller, monodisperse colloidal particles (confining electrons and holes, and boosting radiative recombination) with fewer surface defects (reducing non-radiative recombination). Doping of guanidinium into formamidinium lead bromide PNCs yields limited bulk solubility while creating an entropy-stabilized phase in the PNCs and leading to smaller PNCs with more carrier confinement. The extra guanidinium segregates to the surface and stabilizes the undercoordinated sites. Furthermore, a surface-stabilizing 1,3,5-tris(bromomethyl)-2,4,6-triethylbenzene was applied as a bromide vacancy healing agent. The result is highly efficient PNC-based light-emitting diodes that have current efficiency of 108 cd A−1 (external quantum efficiency of 23.4%), which rises to 205 cd A−1 (external quantum efficiency of 45.5%) with a hemispherical len

A study on protozoan infections (Giardia, Entamoeba, Isoapora and Cryptosporidium) in stray dogs in Ilam province

Giardia, Entamoeba, Isospora and Cryptosporidium are important protozoan parastites that caused diarrhea in human and animals. In the present study, fecal samples were collected fresh, directly from the rectum of 112 stray dogs in Ilam province. Giardia and Entamoeba were concentrated by using the formalin ether sedimentation method followed by the trichrome and iodine staining technique andCryptosporidium  oocysts  were  concentrated  by  using  the  formalin  ether  sedimentation  method  followed by the modified Ziehl-Neelsen staining technique. Of 112 stray dogs, protozoan infections were detected from feces of 46 dogs (41.07%) that Giardia infection was detected from feces of 21 dogs (18.75%), Isospora 17 (15.17%), Cryptosporidium 8 (7.14%) and synchronization infection to 2 protozoan in 9 dogs (8.03%) and to 3 protozoan in 3 (2.67%). In the present study not observed to Entamoeba. No statistically significant differences in prevalence of protozoan parasites occurred between female (34.21 %) and male (55.5 %) stray dogs (p>0/05). But statistically significant differences in prevalence occurred between 1≥0 and 0 ≥1 stray dogs (p>0/05). So that stray dogs of Ilam province can cause infection of human water and food sources

Survey of Experimental Contamination to Ichthyophthirius Multifiliis in Cultural Rainbow Trout Consequently Vaccination with Aquavac Garvetil

Branch. 4 Under graduated students of veterinary medicine and members of young researcher club of Tabriz, Islamic Azad University, Tabriz branch, Tabriz, Iran Garedaghi Y., Khayat Nouri M.H., Kakekhani S., Nazeri M.; Survey of experimental contamination to ichthyophthirius multifiliis in cultural rainbow trout consequently vaccination with aquavac garvetil ABSTRACT The rainbow trout is the only cold water fish in Iran which has specific economic importance. One of the major bacterial diseases among the rainbow trout is streptococcosis which can be controlled through aquavac garvetil vaccine. It has been shown that this vaccine has stimulation effects on specific and non-specific immune system in the fish. So the aim of this study was determination of Ichthyophthirius experimental infectious in rainbow trout after aquavac garvetil vaccination. In this study, 2000 fish (1g) randomly selected and ten infected fish by Ichthyophthirius added to pool after 15 days. After 60 days, fishes randomly divided in control and treatment groups. In treatment group, vaccination was done in two stages. First stage in day 67 which fish were sunk in aquavac garvetil vaccine and in second stage vaccine were administrated orally in day 127. In control group, vaccine were not used. After one month, in both groups, 500 fish randomly were selected and anesthetized, after wet mount preparation the numbers of parasites were counted. Mean of number of parasites compared in control and treatment groups. Results showed that in treatment group after vaccination the number of parasites significantly decreased (p<0.05) compared with control group. This effect of aquavac garvetil vaccine is probably via stimulating effect of this agent on nonspecific immune system in fishes. However study of the mechanism of this vaccine in decreasing of Ichthyophthirius infections needs to more investigation

Hidden phases and colossal insulator-metal transition in single-crystalline T-Nb2O5 thin films accessed by lithium intercalation

Fast migration of lithium (Li)-ions in oxide materials is fundamental to the operation of Li-ion batteries. The intercalation of Li-ions into oxides can further lead to emergent electronic property changes. Some of the fastest Li-ion conductors are 4d oxides, and of these, the niobium oxide polymorph T-Nb2O5 is especially interesting with its two-dimensional fast ion migration channels. However, the growth of single-crystalline T-Nb2O5 films is challenging due to its stability over only a limited synthesis temperature window, the existence of many other polymorphs, and its large orthorhombic unit cell. Here, we first demonstrate the epitaxial growth of single domain T-Nb2O5 thin films, critically with the ion channels oriented perpendicular to the film's surface. We show that the insertion of just a small amount of Li using ionic liquids results in conversion of the initially insulating film to a metallic state with a colossal change in resistivity of almost eleven orders of magnitude. In situ experiments, in conjunction with theoretical calculations, reveal a series of transitions between distinct crystal and electronic structures as the lithium content is systematically increased. These include hidden phases that have not previously been identified. Furthermore, replacing the Au electrode with a Li-oxide electrode allows for a significant reduction of the gate voltage at which metallization takes place. Our study opens a new path towards the exploration of hidden phases and the development of novel electrochemically controlled electronic devices

Li iontronics in single-crystalline T -Nb 2 O 5 thin films with vertical ionic transport channels

Acknowledgements: This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement no. 737109. Funding has been provided by the Alexander von Humboldt Foundation in the framework of the Alexander von Humboldt Professorship to S.S.P.P. endowed by the Federal Ministry of Education and Research. The electrochemical theory of Z.J. and A.K. was supported by the US Department of Energy, Office of Science, Basic Energy Sciences, under award no. DE-SC0019281. F.N.S. acknowledges funding from the Faraday Institution CATMAT project (FIRG016). The oxide structure and phase transition theory of A.M.S. and A.M.R. was supported by the Office of Naval Research, under grant N00014-20-1-2701. The authors acknowledge computational support from the National Energy Research Scientific Computing Center (NERSC) of the DOE and the High-Performance Computing Modernization Office (HPCMO) of the US Department of Defense (DOD). Use of the APS at Argonne National Laboratory was supported by the US Department of Energy, Office of Science, Office of Basic Energy Sciences, under contract No. DE-AC02-06CH11357. We thank C. Guillemard at ALBA synchrotron and J. H. Jin at GERI for their assistance with gating of XANES and TEM samples, respectively.The niobium oxide polymorph T-Nb2O5 has been extensively investigated in its bulk form especially for applications in fast-charging batteries and electrochemical (pseudo)capacitors. Its crystal structure, which has two-dimensional (2D) layers with very low steric hindrance, allows for fast Li-ion migration. However, since its discovery in 1941, the growth of single-crystalline thin films and its electronic applications have not yet been realized, probably due to its large orthorhombic unit cell along with the existence of many polymorphs. Here we demonstrate the epitaxial growth of single-crystalline T-Nb2O5 thin films, critically with the ionic transport channels oriented perpendicular to the film’s surface. These vertical 2D channels enable fast Li-ion migration, which we show gives rise to a colossal insulator–metal transition, where the resistivity drops by 11 orders of magnitude due to the population of the initially empty Nb 4d0 states by electrons. Moreover, we reveal multiple unexplored phase transitions with distinct crystal and electronic structures over a wide range of Li-ion concentrations by comprehensive in situ experiments and theoretical calculations, which allow for the reversible and repeatable manipulation of these phases and their distinct electronic properties. This work paves the way for the exploration of novel thin films with ionic channels and their potential applications