Adipose‐Derived Biogenic Nanoparticles for Suppression of Inflammation

Extracellular vesicles secreted from adipose‐derived mesenchymal stem cells (ADSCs) have therapeutic effects in inflammatory diseases. However, production of extracellular vesicles (EVs) from ADSCs is costly, inefficient, and time consuming. The anti‐inflammatory properties of adipose tissue‐derived EVs and other biogenic nanoparticles have not been explored. In this study, biogenic nanoparticles are obtained directly from lipoaspirate, an easily accessible and abundant source of biological material. Compared to ADSC‐EVs, lipoaspirate nanoparticles (Lipo‐NPs) take less time to process (hours compared to months) and cost less to produce (clinical‐grade cell culture facilities are not required). The physicochemical characteristics and anti‐inflammatory properties of Lipo‐NPs are evaluated and compared to those of patient‐matched ADSC‐EVs. Moreover, guanabenz loading in Lipo‐NPs is evaluated for enhanced anti‐inflammatory effects. Apolipoprotein E and glycerolipids are enriched in Lipo‐NPs compared to ADSC‐EVs. Additionally, the uptake of Lipo‐NPs in hepatocytes and macrophages is higher. Lipo‐NPs and ADSC‐EVs have comparable protective and anti‐inflammatory effects. Specifically, Lipo‐NPs reduce toll‐like receptor 4‐induced secretion of inflammatory cytokines in macrophages. Guanabenz‐loaded Lipo‐NPs further suppress inflammatory pathways, suggesting that this combination therapy can have promising applications for inflammatory diseases.     

The Light‐Induced Field‐Effect Solar Cell Concept – Perovskite Nanoparticle Coating Introduces Polarization Enhancing Silicon Cell Efficiency

Solar cell generates electrical energy from light one via pulling excited carrier away under built‐in asymmetry. Doped semiconductor with antireflection layer is general strategy to achieve this including crystalline silicon (c‐Si) solar cell. However, loss of extra energy beyond band gap and light reflection in particular wavelength range is known to hinder the efficiency of c‐Si cell. Here, it is found that part of short wavelength sunlight can be converted into polarization electrical field, which strengthens asymmetry in organic‐c‐Si heterojunction solar cell through molecule alignment process. The light harvested by organometal trihalide perovskite nanoparticles (NPs) induces molecular alignment on a conducting polymer, which generates positive electrical surface field. Furthermore, a “field‐effect solar cell” is successfully developed and implemented by combining perovskite NPs with organic/c‐Si heterojunction associating with light‐induced molecule alignment, which achieves an efficiency of 14.3%. In comparison, the device with the analogous structure without perovskite NPs only exhibits an efficiency of 12.7%. This finding provides a novel concept to design solar cell by sacrificing part of sunlight to provide “extra” asymmetrical field continuously as to drive photogenerated carrier toward respective contacts under direct sunlight. Moreover, it also points out a method to combine promising perovskite material with c‐Si solar cell.     

Reflectance reduction of InP wafers after high-temperature annealing

Broadband reduction of light reflection from the surface of InP wafers after high-temperature annealing in air has been observed. In the transparency region of the material, the reflection drop is accompanied by increasing transmission of light through the wafer. The spectral position of a deep minimum of the reflection coefficient can be tuned, by varying the temperature and the time of annealing, in a wide spectral range from ultraviolet to infrared. The effect is due to formation of thermal oxide layers on the surfaces of the wafer with optical parameters favorable for antireflection.     

Anomalous independence of multiple exciton generation on different group IV-VI quantum dot architectures

Multiple exciton generation (MEG) in PbSe quantum dots (QDs), PbSe(x)S(1-x) alloy QDs, PbSe/PbS core/shell QDs, and PbSe/PbSe(y)S(1-y) core/alloy-shell QDs was studied with time-resolved optical pump and probe spectroscopy. The optical absorption exhibits a red-shift upon the introduction of a shell around a PbSe core, which increases with the thickness of the shell. According to electronic structure calculations this can be attributed to charge delocalization into the shell. Remarkably, the measured quantum yield of MEG, the hot exciton cooling rate, and the Auger recombination rate of biexcitons are similar for pure PbSe QDs and core/shell QDs with the same core size and varying shell thickness. The higher density of states in the alloy and core/shell QDs provide a faster exciton cooling channel that likely competes with the fast MEG process due to a higher biexciton density of states. Calculations reveal only a minor asymmetric delocalization of holes and electrons over the entire core/shell volume, which may partially explain why the Auger recombination rate does not depend on the presence of a shell.     

MASS SELECTED ION BEAM DEPOSITION: A TOOL FOR PARAMETRIC GROWTH STUDIES, PROCESS DEVELOPMENT AND FABRICATION OF DIAMONDLIKE FILMS

Diamondlike films have unique properties that can be tailored between those of diamond and those of graphite to meet industrial applications. The purpose of this review is to emphasize the ability to prepare films with specific properties through control of the deposition parameters. The three basic approaches, plasma deposition, chemical vapor deposition, and ion beam deposition, are presented. Since the first two methods consist of complex chemical-physical systems which limit the possibilities for controlled parametric studies, the focus herein is on the latter technique. This work presents the unique capabilities of mass-selected carbon ion beam deposition in controlling deposition parameters over a wide range, particularly when combined with in-situ analysis of film evolution. The role of different deposition parameters on diamond film growth is discussed. The Houston deposition system that manifests the above features is described. A summary of results of some ongoing experiments is given to demonstrate the system capabilities for both parametric studies of diamondlike film growth and actual production of diamondlike films.     

Electron microscopy studies of amphiphilic self-assemblies on vitreous ice

The structure of self-assemblies of amphiphiles formed at the air–aqueous solution interface can be determined by cryo transmission electron microscopy (Cryo-TEM). The method is based on fast vitrification of the thin layer of aqueous solution covered with amphiphilic monolayer by plunging the specimen into liquid ethane at its freezing point. During the process of fast cooling the aggregates maintain their two-dimensional crystalline integrity and structure, as demonstrated by comparative studies involving grazing incidence X-ray diffraction (GID) at the air-solution interface, and the Cryo-TEM measurements of the same amphiphilic systems on vitreous ice. Bright-field and dark-field images from the Cryo-TEM observations provide more detailed information than from epifluorescence and Brewster angle microscopy. Furthermore, the electron diffraction patterns have the additional advantage that they allow structural characterization of the crystallites almost at a molecular level, and furnish data on micro twinning and defects occurring between crystalline domains. Cryo-TEM has been applied to elucidate the structure of 2-D and 3-D self-aggregates of amphiphilic alcohols, acids and their cadmium salts, bola-amphiphiles and mixed monolayers. Epitaxial crystallization of hexagonal ice underneath the monolayer of long chain alcohol was also directly demonstrated by this method.     

Scanning tunneling microscopy measurements of the initial erosion of graphite by hyperthermal atomic oxygen and neon

Highly ordered pyrolitic graphite (HOPG) was bombarded by low-energy (30eV) O⁺ and Ne⁺ at fluxes in the range of 10¹⁵–10¹⁶ ions cm⁻². The initial erosion of a few monolayers was studied with the aid of scanning tunneling microscopy (STM). Damage consisting of hillocks was observed for both O⁺ and Ne⁺, and the damage density increased with dose. O⁺-bombarded surfaces exhibited partial exfoliation of one to two monoatomic layers (propably as a result of chemical erosion), which was absent for Ne⁺ bombardment. Surface reconstruction of damaged areas was observed. The present work is the first step in an STM study of the effects of atomic oxygen erosion of graphite/epoxy composites in space.