ABSTRACT
Luminescent materials with high thermal stability and quantum efficiency are extensively desired for indoor illumination. In this research, a series of Eu3+-activated KGd2F7 red-emitting nanoparticles were prepared at room temperature and their phase structure, morphology, luminescence properties, as well as thermal stability, have been studied in detail. Excited by 393 nm, the resultant nanoparticles emitted bright red emissions and its optimal status was realized when the Eu3+ content was 30 mol%, in which the concentration quenching mechanism was triggered by electric dipole-dipole interaction. Through theoretical analysis via the Judd-Ofelt theory, one knows that Eu3+ situates at the high symmetry sites in as-prepared nanoparticles. Moreover, the internal and extra quantum efficiencies of designed nanoparticles were dependent on Eu3+ content. Furthermore, the studied nanoparticles also had splendid thermal stability and the corresponding activation energy was 0.18 eV. Additionally, via employing the designed nanoparticles as red-emitting constituents, a warm white light-emitting diode (white-LED), which exhibits low correlated color temperature (4456 K), proper luminous efficiency (17.2 lm/W) and high color rendering index (88.3), was developed. Our findings illustrate that Eu3+-activated KGd2F7 nanoparticles with bright red emissions are able to be used to promote the performance of white-LED.
ABSTRACT
Exosomes are a heterogeneous group of nano-sized natural membrane vesicles released from various cells and exist in body fluids. Different from the previous understanding of the function of exosomes as "garbage bins", exosomes act as carriers with many kinds of bioactive molecules (e.g., proteins, lipids, and nucleic acids) to play an important role in cell-cell communication. Growing evidence in recent years has suggested that exosomes also play some roles in the pathogenesis, diagnosis, and treatment modalities of some brain diseases, including ischemic stroke, Alzheimer's disease, Parkinson's disease, multiple sclerosis, and brain cancers. Exosomes as therapeutic drug carriers for brain drug delivery have received extensive attention as well as exosomes can overcome the blood-brain barrier (BBB). However, the low targeting ability and size-dependent cellular uptake of native exosomes could profoundly affect the delivery performance of exosomes. Recent studies have indicated that engineered exosomes can increase the drug uptake efficiency and the subsequent drug efficacy. In the present paper, we will briefly introduce the engineering methods and applications of engineered exosomes in the treatment of brain diseases, and then focus on discussing the advantages and challenges of exosome- based drug delivery platforms to further enrich and boost the development of exosomes as a promising drug delivery strategy for brain diseases.
Subject(s)
Exosomes , Parkinson Disease , Cell Communication , Drug Carriers/metabolism , Drug Delivery Systems , Exosomes/metabolism , Humans , Parkinson Disease/drug therapy , Parkinson Disease/metabolismABSTRACT
ZnTe and ZnTe : Cu polycrystalline films were fabricated by means of co-evaporating at room temperature. The sturcture and distribution of various elements were studied by XPS and XRD. The XRD results show that the phase structure of the films deposited at different substrate temperature almost remains unchanged, XPS analysis shows that the compositional dependence of sputtering time is different for the films deposited at different deposition rate. The distribution of Cu in the film grows with the increase in the sputtering time, and reaches a maximum, then falls down rapidly. According to the transformation of the distribution of Cu we excogitated how to prevent Cu diffusion in ZnTe films. Considering Cu as a function of time, ZnTe films were first deposited at the substrate temperature of 70 degrees C, and then ZnTe : Cu films were deposited at room temperature, effectively preventing the diffusion of Cu atom, and thus improving the efficiency of CdTe solar cells.
ABSTRACT
ZnTe and ZnTe: Cu polycrystalline films were fabricated by means of co-evaporating at room temperature. The relationships between conductivity of the films and temperature were measured. Chemical compositions of ZnTe and ZnTe: Cu polycrystalline films were obtained by using XPS, and the changes of chemical composition before and after anneal were analyzed. The results showed that the conductivity of ZnTe rose linearly with the temperature, and Te was enriched on the margin of every sample's surface; With the rise in temperature, the conductivity of ZnTe: Cu films became abnormal, the oxidization of Te became very obvious and Zn diffused from the bulk to the surface. The composition became more uniform and all peaks became stronger. Carrier concentration caused by CuxTe appeared, resulting in the abnormal relationship between conductivity of the films and temperature.
