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•Fluorine-free hydrophobic/oleophilic nanofibrous membranes were prepared.•PDMS enabled to fine-tune the wettability of nanofibers.•Gravity-driven filtration of oil-rich emulsions was ...achieved.•Inclusion of PDMS in PMMA nanofibers improved their separation efficiency.
Emulsions are very challenging to separate due to their small droplet size. Recent attention has been drawn to gravity-driven filtration using membranes due to their simple, easy and yet efficient way of separating emulsions. To achieve this, membranes with high porosity and high selectivity must be prepared. Nanofibrous membranes prepared through electrospinning are recently being explored for their excellent bulk properties such as high porosity and tunable wettability. In this study, a fluorine-free hydrophobic/oleophilic matrix was fabricated through electrospinning of the blend poly(methyl methacrylate)/ polydimethylsiloxane (PMMA/PDMS) to form highly porous nanofibrous membranes for gravity-driven separation of oil-rich emulsions is first investigated. The combination of high porosity (77.6%), large pore size (5.8 µm), and high hydrophobicity (154°) of the composite membranes (PMMA blended with 60 wt% PDMS) allowed it to breakdown and separate a variety of oil-rich emulsions such as water-in-hexane, water-in-hexadecane, water-in-diesel, and water-in-soybean with separation efficiency of 99.0%, 99.5%, 99.25% and 97.75%, respectively. The presence of methyl groups endowed the membrane with the ability to efficiently repel water droplets from passing through the membrane thus, allowing the successful breakdown of complex oils (although at a slower permeation rate). All aspects considered, PMMA/PDMS nanofibrous membrane appear to be a promising material for effective and fast gravity-driven filtration of oil-rich emulsions.
The response of a single CdS‐nanowire‐based nanogenerator to excitation by visible light is investigated. White light reduces the height of the Schottky barrier that existis at the tip nanowire ...contact, leading to possible barrier breakthrough and a contact‐mode change from Schottky to quasi‐Ohmic. This work demonstrates the triple coupling among semiconducting, piezoelectric, and optoelectric properties, which may be useful for designing new optopiezotronic devices.
Many applications, such as photovoltaic systems, uninterruptible power supplies, and automobile headlamps, need a high step-up DC–DC converter without isolation. The conventional boost converter has ...the advantages of simple topology and easy control. However, it has some shortcomings, such as insufficient step-up voltage ratio and poor efficiency when operating at large duty-cycle conditions. One of the popular topologies used to overcome these problems is the coupled-inductor boost converter. It utilizes the turn ratio of the coupled inductor to realize a higher step-up voltage ratio. The drawback is that the leakage inductance of the coupled inductor causes a huge voltage spike when the power switches are turned off. Moreover, because coupled inductors are characterized by their large volume and high profile, a conventional coupled-inductor boost converter is unsuited for photovoltaic systems, such as the solar microinverter. This study proposes a novel high-step-up boost converter to solve these problems. This proposed converter uses dual coupled inductors instead of the conventional coupled-inductor boost converter. The secondary side of the coupled inductor is connected in series to increase the step-up voltage ratio. The proposed converter utilizes active clamping to achieve zero-voltage switching (ZVS) for suppressing voltage spike and improving conversion efficiency. In addition, low-profile designs can be fulfilled easily for solar microinverters. The proposed converter and its control method are introduced. The operation principle, circuit characteristics, and circuit analysis are presented. A prototype converter with 300 W output power 25–40 VDC input voltage and 200 VDC output voltage was tested. All functions, including high step-up voltage ratio, ZVS, and active clamping, were achieved, and the highest efficiency was around at 94.7%.
As disinfection is employed extensively, disinfection by-product bromate has become an emerging environmental issue due to its carcinogenic toxicity. For developing an effective alternative approach ...for reducing bromate, cobalt and nickel-based Prussian Blue (PB) analogues are proposed here for incorporating a convenient reducing agent, NaBH
4
(i.e., a H
2
-rich reagent) for reducing bromate to bromide as cobalt and nickel are recognized as effective metals for catalyzing hydrolysis of NaBH
4
, and PB exhibits versatile catalytic activity. While CoPB and NiPB are comprised of the same crystalline structure, CoPB exhibits slightly higher specific surface area, more reductive surface, and more superior electron transfer than NiPB, enabling CoPB to accelerate bromate reduction. CoPB also exhibits a higher affinity towards NaBH
4
than NiPB based on density functional theory calculations. Moreover, CoPB also exhibits a relatively low activation energy (i.e., 59.5 kJ/mol) of bromate reduction than NiPB (i.e., 63.2 kJ/mol). Furthermore, bromate reduction by CoPB and NiPB could be also considerably enhanced under acidic conditions, and CoPB and NiPB could still effectively remove bromate even in the presence of nitrate, sulfate and phosphate. CoPB and NiPB are also validated to be recyclable for reducing bromate, indicating that CoPB and NiPB are promising heterogeneous catalysts for reducing bromate.
The objective of this study was to evaluate the effects of window films on indoor environmental conditions and electricity consumption of air conditioning. The research focused on the performance of ...different window films (HAG, RG), taking into account variations from different building orientations. The findings of this research indicated that building orientation could significantly influence the duration of direct sunlight entering the interior, with the areas closer to the glass being more susceptible to the effects of outdoor temperature and solar radiation. The clear glass with heat-absorbing film (HAG) and reflective film (RG) both reduced the indoor temperature and indoor illuminance while increasing indoor comfort. The RG could accumulate less heat on the glass surface compared with the HAG. The glass temperature of the RG will be lower than the HAG. The electricity-saving ratios of the HAG were 1.4%, 1.9%, 1.4%, and 1.2%, respectively, when facing the east, south, west, and northwest orientations compared with the clear glass (OG). The electricity-saving ratios of the RG were 3%, 4.2%, 4.2%, and 10.3%, respectively.
This study presents the topology of a three-phase LLC resonant converter with matrix transformers. The three-phase LLC resonant converter has the advantages of conventional LLC resonant converters, ...including zero-voltage switching at the primary side, zero-current switching at the secondary side, high-frequency feasibility, and high efficiency. Moreover, it has additional advantages that differ from conventional LLC, including low output capacitor current ripple, natural current sharing in three resonant currents, and a high power level. As a result of the above mentioned characteristics, LLC topology has been used in many electric vehicle charging systems, server power systems, and other high-power applications. However, as the power level becomes higher and higher, the input voltage is usually too high to reduce conduction loss, and the output current also increases. This situation makes transformer design more difficult. The increasing current means more core and copper loss, and the heat dissipation of the transformer becomes more difficult. Matrix transformer technology can improve this problem directly and simply. By utilizing matrix transformers, which are primary series connected and secondary parallel connected, the primary voltage stress and secondary current stress of the transformers can be reduced, and the output current can be distributed. The analysis of the proposed converter in this study includes a circuit operation introduction, a time-domain analysis, calculation of the transfer ratio curve in the frequency domain, and a loss analysis. The theoretical analysis and performance of the proposed converter are verified. A three-phase LLC resonant converter with matrix transformers prototype is built with a high input voltage of 800-VDC and high output current of 200-A. The output voltage is 100-VDC. The waveform and efficiency data will be shown in the experimental results.
miRNAs are a family of approximately 22-nuleotide-long noncoding RNAs involved in the formation and progress of tumors. Since traditional methods for the detection of miRNAs expression have many ...disadvantages, we developed a simple method called polyA RT PCR. With this method, we detected a series of miRNAs and found that mir-126 is one of the miRNAs underexpressed in breast cancer cells. Flow cytometry analysis showed that mir-126 inhibited cell cycle progression from G1/G0 to S. Further studies revealed that mir-126 targeted IRS-1 at the translation level. Knocking down of
IRS-1 suppresses cell growth in HEK293 and breast cancer cell MCF-7, which recapitulates the effects of mir-126. In conclusion, we developed a simple method for high-throughput screening of miRNAs and found that mir-126, a cell growth suppressor, targets
IRS-1.
In this paper, carbon aerogel (CA)-polyaniline (PANI) composites were prepared and first applied in the study of H2S gas sensing. Here, 1 and 3 wt% of as-obtained CA powder were blended with PANI to ...produce composites, which are denoted by PANI-CA-1 and PANI-CA-3, respectively. For the H2S gas-sensing studies, the interdigitated electrode (IDE) was spin-coated by performing PANI and PANI-CA composite dispersion. The H2S gas-sensing properties were studied in terms of the sensor’s sensitivity, selectivity and repeatability. IDE coated with PANI-CA composites, as compared with pristine PANI, achieved higher sensor sensitivity, higher selectivity and good repeatability. Moreover, composites that contain higher loading of CA (e.g., 3 wt%) perform better than composites with lower loading of CA. At 1 ppm, PANI-CA-3 displayed increased sensitivity of 452% at relative humidity of 60% with a fast average response time of 1 s compared to PANI.
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