Design and Operation of a Pressure-Controlled Inlet for Airborne Sampling with an Aerodynamic Aerosol Lens

Two pressure-controlled inlets (PCI) have been designed and integrated into the Aerodyne Aerosol Mass Spectrometer (AMS) inlet system containing an aerodynamic aerosol lens system for use in airborne measurements. Laboratory experiments show that size calibration and mass flow rate into the AMS are not affected by changes in upstream pressure (P ₀ ) of the PCI as long as the pressure within the PCI chamber (P _PCI ) is controlled to values lower than P ₀ . Numerous experiments were conducted at different P _PCI , P ₀ , and AMS lens pressures (P _Lens ) to determine particle transmission efficiency into the AMS. Based on the results, optimum operating conditions were selected which allow for constant pressure sampling with close to 100% transmission efficiency of particles in the size range of ～ 100–700 nm vacuum aerodynamic diameter (d _va ) at altitudes up to ～ 6.5 km. Data from an airborne field study are presented for illustration.     

A study of concept-based similarity approaches for recommending program examples

This paper investigates a range of concept-based example recommendation approaches that we developed to provide example-based problem-solving support in the domain of programming. The goal of these approaches is to offer students a set of most relevant remedial examples when they have trouble solving a code comprehension problem where students examine a program code to determine its output or the final value of a variable. In this paper, we use the ideas of semantic-level similarity-based linking developed in the area of intelligent hypertext to generate examples for the given problem. To determine the best-performing approach, we explored two groups of similarity approaches for selecting examples: non-structural approaches focusing on examples that are similar to the problem in terms of concept coverage and structural approaches focusing on examples that are similar to the problem by the structure of the content. We also explored the value of personalized example recommendation based on student's knowledge levels and learning goal of the exercise. The paper presents concept-based similarity approaches that we developed, explains the data collection studies and reports the result of comparative analysis. The results of our analysis showed better ranking performance of the personalized structural variant of cosine similarity approach.     

Cationic metalloporphyrins for synthesis of conducting,water-soluble polyaniline

Catalytic oxidative polymerization of aniline was performed using the tetrapyridylporphyrin (TPyP) complexes of iron (III), manganese (III) and cobalt (III). It was found that the cationic metalloporphyrin catalyzed the polymerization of aniline more efficiently than the anionic metalloporphyrins, when using aqueous H₂O₂. The reaction was carried out in the presence of sulfonated polystyrene (SPS) as a template at different pHs, ranging from 1 to 5, and the best results were obtained at pH 2. Formation of water-soluble polyaniline (PANI) was characterized by UV–vis, FT-IR spectroscopy and cyclic voltammetry (CV). FT-IR and UV–vis spectra confirm the formation of the conducting form of PANI. Cyclic voltammetry measurements demonstrate that the polymer has convenient electroactivity.     

In situ synthesized chitosan–gelatin/ZnO nanocomposite scaffold with drug delivery properties: Higher antibacterial and lower cytotoxicity effects

In this work, chitosan–gelatin/zinc oxide nanocomposite hydrogel scaffolds (CS–GEL/nZnO) were prepared via in situ synthesis of ZnO nanoparticles (nZnO) to reach a scaffold with both inherent antibacterial and drug delivery properties. The prepared nanocomposite hydrogel scaffolds were characterized using scanning electron microscopy, transmission electron microscopy, atomic absorption spectrometer, Fourier transform infrared spectroscopy, and X-ray diffraction. In addition, swelling, biodegradation, antibacterial, cytocompatibility, and cell attachment of the scaffolds were evaluated. The results showed that the prepared scaffolds had high porosity with a pore size of 50–400 μm and nZnO were well distributed without any agglomeration on the CS–GEL matrix. In addition, the nanocomposite scaffolds showed enhanced swelling, biodegradation, and antibacterial properties. Moreover, the drug delivery studies using naproxen showed that nZnO could control naproxen release. Cytocompatibility of the samples was proved using normal human dermal fibroblast cells (HFF2). In comparison to the previous reports which nZnO were simply added to the matrix of the scaffold, in situ synthesis of nZnO was led to higher antibacterial and lower cytotoxicity effects as a result of well distribution of nZnO in this method. According to the findings, the in situ synthesized CS–GEL/nZnO is strongly recommended for biomedical applications especially skin tissue engineering. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47590.     

Synthesis,characterization, and drug‐release behavior of novel PEGylated bovine serum albumin as a carrier for anticancer agents

To develop a novel pH‐sensitive PEGylated carrier for protein‐based anticancer agents, we modified bovine serum albumin (BSA) with poly(ethylene glycol) citrate ester (PEG–CA) through amidation with its amino groups. Increasing the mixing ratio of albumin from 3 to 6 with respect to PEG–CA resulted in a 2‐fold increase in the degree of albumin modification. Adriamycin (ADR)‐loaded PEG–CA–BSA hydrogels and microparticles were prepared, and the cumulative amounts of ADR released from the PEG–CA–BSA hydrogels (phosphate‐buffered saline, pH 7.4) showed that all the PEG‐CA‐BSA_(x) (x represents degree of substitution of PEG to amino group of albumin, i.e. 26%, 28%, 31% and 49%) hydrogels had lower ADR release rates with a slight initial burst release. During the first 24 h, the cumulative releases were 15.5% for PEG–CA–BSA₍₄₉₎, 24% for PEG–CA–BSA₍₃₁₎, 31% for PEG–CA–BSA₍₂₈₎, and 38% for PEG–CA–BSA₍₂₆₎. Afterward, all the release rates slowed, and they were almost in the following order: PEG–CA–BSA₍₂₆₎ > PEG–CA–BSA₍₂₈₎ > PEG–CA–BSA₍₃₁₎ > PEG–CA–BSA₍₄₉₎. The release rates of ADR from the microparticles were dependent on the amount of glutaraldehyde. According to our findings, a higher PEG–CA/BSA molar ratio led to a reduced cumulative amount of ADR released from the hydrogels, whereas higher release rates were observed for microparticles with a lower amount of BSA in the conjugates in a pH‐dependent manner. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

High Ionic Conductivity Motivated by Multiple Ion-Transport Channels in 2D MOF-Based Lithium Solid State Battery

Metal-organic frameworks (MOFs) have been proposed as novel fillers for constructing polymer solid electrolytes based composite electrolytes. However, MOFs are generally used as passive fillers, in-depth revealing the binding mode between MOFs and polyethylene oxide (PEO), the critical role of MOFs in facilitating Li⁺ transport in solid electrolytes is full of challenges. Herein, inspired by density functional theory (DFT) the 2D-MOF with rich unsaturated metal coordination sites that can bind the O atom in PEO through the metal–oxygen bond,  anchor TFSI⁻ to release Li⁺, resulting in a remarkable Li⁺ transference number of 0.58, is reported according well with the experimental results and molecular dynamics (MD) simulation. Impressively, after the introduction of the 2D-MOF, the Li⁺ can rapidly hop along the benzene ring center within the 2D-MOF plane, and the interface between the benzene ring and PEO can also serve as a fast Li⁺ migration pathway, delivering multiple ion-transport channels, which present a high ion conductivity of 4.6 × 10⁻⁵ S cm⁻¹ (25 °C). The lithium symmetric battery is stable for 1300 h at 60 °C, 0.1 mA cm⁻². The assembled lithium metal solid state battery maintains high capacity of 162.8 mAh g⁻¹ after 500 cycles at 60 °C and 0.5 C. This multiple ion-transport channels approach brings new ideas for designing advanced solid electrolytes.     

Improved Cytotoxicity and Induced Apoptosis in HeLa Cells by Co-loading Vitamin E Succinate and Curcumin in Nano-MIL-88B-NH2

One of the strategies for improved therapeutic effects in cancer therapy is combination chemotherapy. In this study, a flexible nano-MOF (Fe-MIL-88B-NH₂) was synthesized in a sonochemical process, then co-loaded with α-tocopheryl succinate (TOS) and curcumin (CCM). The anticancer activity of co-loaded Fe-MIL-88B-NH₂ (Fe-MIL-88B-NH₂/TOS@CCM) against the HeLa cells was compared with that of the single-loaded counterpart (Fe-MIL-88B-NH₂@CCM). MTT analysis indicates improved cytotoxicity of Fe-MIL-88B-NH₂/TOS@CCM. The data from the cell apoptosis assay indicated more apoptosis in the case of the co-loaded nano-MOF. This study indicates the positive effect of the presence of TOS on enhancing the anticancer effect of Fe-MIL-88B-NH₂@CCM to prepare a more efficient drug delivery nanosystem.     

Trapping Lithium Selenides with Evolving Heterogeneous Interfaces for High-Power Lithium-Ion Capacitors

Transition metal selenides anodes with fast reaction kinetics and high theoretical specific capacity are expected to solve mismatched kinetics between cathode and anode in Li-ion capacitors. However, transition metal selenides face great challenges in the dissolution and shuttle problem of lithium selenides, which is the same as Li-Se batteries. Herein, inspired by the density functional theory calculations, heterogeneous can enhance the adsorption of Li₂Se relative to single component selenide electrodes, thus inhibiting the dissolution and shuttle effect of Li₂Se. A heterostructure material (denoted as CoSe₂/SnSe) with the ability to evolve continuously (CoSe₂/SnSe→Co/Sn→Co/Li₁₃Sn₅) is successfully designed by employing CoSnO₃-MOF as a precursor. Impressively, CoSe₂/SnSe heterostructure material delivers the ultrahigh reversible specific capacity of 510 mAh g⁻¹ after 1000 cycles at the high current density of 4 A g⁻¹. In situ XRD reveals the continuous evolution of the interface based on the transformation and alloying reactions during the charging and discharging process. Visualizations of in situ disassembly experiments demonstrate that the continuously evolving interface inhibits the shuttle of Li₂Se. This research proposes an innovative approach to inhibit the dissolution and shuttling of discharge intermediates (Li₂Se) of metal selenides, which is expected to be applied to metal sulfides or Li-Se and Li-S energy storage systems.