Recombination lifetime profiling in very thin Si epitaxial layersused for bipolar VLSI

A recently proposed measurement technique (P. Spirito and G. Cocorullo, IEEE Trans. Electron Devices, vol.ED-32, no.9, p.1708-13, 1985) to evaluate the recombination lifetime along epitaxial layers is used to characterize the quality of very thin Si epitaxial layers used for bipolar technology. The experimental results show the ability of the technique to give accurate and detailed information on the quality of epilayers that could be useful in monitoring and improving the growth process. The experimental results show that the lifetime values in thin epilayers are not correlated with doping profiles in the same layers; moreover, they are only slightly dependent on different processes used to make the test devices     

Modulating drug release from poly(lactic-co-glycolic) acid microparticles by the addition of alginate and pectin

The aim of the present work is the characterization of PLGA microparticles including biopolymers for the controlled release of tilmicosin, a broad-spectrum antibiotic. Microparticles were prepared using the double-emulsion solvent evaporation technique. The effect of alginate and pectin incorporation over particle size and porosity, encapsulation efficiency (EE) and pH-responsive drug release was evaluated. Formulations presented a mean particle size of 5.5 μm approximately and a drug EE ranged from 22%–57%. PLGA-Alginate particles showed an increased porosity. Tilmicosin release profiles from PLGA and PLGA-biopolymer microparticles were affected by the particular combination of polymers and the pH of the release medium. The experimental data was simulated using a mathematical model, which takes into account the autocatalytic polymer degradation and the different mechanisms of drug transport. The combination of PLGA and biopolymers strongly influenced the morphology of the particles, offering the possibility of controlling the drug release profiles according to the therapy.     

Instable mechanisms during unclamped operation of high power IGBT modules

The behaviour in terms of robustness during unclamped operations of power IGBT modules is presented. The experimental characterization is aimed to identify the main instable phenomena during unclamped turn-off in power IGBT modules. Several devices of different generations, current and voltage ratings have been analyzed. Thanks to a non-destructive experimental set-up, it is possible to observe instable phenomena without causing the damage of the device under test. In this paper, it is shown that the destructive conditions during unclamped operations are preceded by precursors on the gate side which indicate instable phenomena taking place inside the device. The dependence of the destructive phenomenon on the driver conditions are widely and exhaustively analyzed.     

The robustness of series-connected high power IGBT modules

The behaviour in terms of robustness of series-connected high power IGBT modules is presented, arranged in a topology which ensures voltage balance on IGBT’s and diodes by means of a simple auxiliary circuit applied directly on the high power devices, which are used in hard switching mode. Analyses in terms of IGBT and diode SOA (safe operating area), collector to emitter voltage gradient and short circuit condition are reported as well as an extended experimental characterisation. Both analyses confirm superior switching rating and system reliability, by using two series-connected IGBT in substitution of a single module, same current and double voltage rated. Moreover, thanks the auxiliary circuit presence, the robustness of total system is maintained also in extreme operating conditions.     

Recombination measurement of n-type heavily doped layer in high/lowsilicon junctions

The hole lifetime within a heavily doped n⁺ region has been determined using a measurement technique which evaluates the effective recombination velocity of n-n⁺ interfaces. The recombination model of a high/low junction is reviewed. The experiment is described. The measurement results are presented and discussed. Measurements of n⁺ layers of different types, like substrates, implanted buried layers, and diffused layers, suggest that the minority-carrier lifetime of such regions can be strongly degraded by the device fabrication processes. Results are consistent with the Shockley-Reed-Hall (SRH) lifetime value, which is two orders of magnitude lower than previously published values for bulk material     

PLGA nano- and microparticles for the controlled release of florfenicol: Experimental and theoretical study

In this study, PLGA particle systems were studied for the controlled release of florfenicol, a broad spectrum antibiotic used in veterinary treatments. The emulsion-solvent evaporation technique was used for particle preparation. To evaluate the particle size, entrapment efficiency, and drug release behavior, factors such as solvent type, emulsification time and methods, and drug to polymer ratio were investigated. The results showed that the use of ethyl acetate and 2.5 min of ultrasonication or 30 min of homogenization can lead to sub-micron and micron-sized particles, respectively. Sizes between 200–300 nm and 2–3 μm were obtained for ultrasonication and homogenization procedures, respectively. Entrapment efficiencies were around 20% for all systems and release profiles were size dependent. In addition, a mathematical model was implemented to simulate the florfenicol transport. The model predicts the florfenicol release and takes into account the particle size, polymer molecular weight, and autocatalytic polymer degradation. Simulation results are in good agreement with experimental results. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47248.     

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.     

Experimental study of charge generation mechanisms in power MOSFETs due to energetic particle impact

Even though low voltage MOSFETs are fairly intrinsically robust to SEB, the high current pulses that arise in certain charge generating mechanisms may lead to circuit malfunction. In this work, for the first time, the current pulses induced by ion impacts in new generation commercial power MOSFETs are characterized by a statistical analysis. This approach allows us to evidence the existence, in these devices, of two different charge generation mechanisms. Furthermore, the capability to easily quantify these phenomena provides useful information for the design of circuits using these MOSFETs. The pulse shape and the total charge generated by the impact of an energetic ion are studied in relation to the energy and species of the ion and the applied voltage between drain and source.     

A Facile Magnetic Extrusion Method for Preparing Endosome-Derived Vesicles for Cancer Drug Delivery

To date, the scaled-up manufacturing and efficient drug loading of exosomes are two existing challenges limiting the clinical translation of exosome-based drug delivery. Herein, a facile magnetic extrusion method is developed for preparing endosome-derived vesicles, also known as exosome mimetics (EMs), which share the same biological origin and similar morphology, composition, and biofunctions with native exosomes. The high yield and consistency of this magnetic extrusion method help to overcome the manufacturing bottleneck in exosome research. Moreover, the proposed standardized multi-step method readily facilitates the ammonium sulfate gradient approach to actively load chemodrugs such as doxorubicin into EMs. The engineered EMs developed and tested here exhibit comparable drug delivery properties as do native exosomes, and potently inhibit tumor growth by delivering doxorubicin in an orthotopic breast tumor model. These findings demonstrate that EMs can be prepared in a facile and scaled-up manner as a promising biological nanomedicine for cancer drug delivery.