Data analysis on social media traces for detection of <Emphasis Type="Italic">“spam”</Emphasis> and <Emphasis Type="Italic">“don’t care”</Emphasis> learners

Classification methods are becoming more and more useful as part of the standard data analyst’s toolbox in many application domains. The specific data and domain characteristics of social media tools used in online educational contexts present the challenging problem of training high-quality classifiers that bring important insight into activity patterns of learners. Currently, standard and also very successful model for classification tasks is represented by decision trees. In this paper, we introduce a custom-designed data analysis pipeline for predicting “spam” and “don’t care” learners from eMUSE online educational environment. The trained classifiers rely on social media traces as independent variables and on final grade of the learner as dependent variables. Current analysis evaluates performed activities of learners and the similarity of two derived data models. Experiments performed on social media traces from five years and 285 learners show satisfactory classification results that may be further used in productive environment. Accurate identification of “spam” and “don’t care” users may have further a great impact on producing better classification models for the rest of the “regular” learners.     

Electric field driven addressing of ATPS droplets in microfluidic chips

The possibility of controlled droplet motion (droplet addressing) mediated by DC electric field in aqueous two-phase systems (ATPS) is here reported for the first time. Three ATPS of polyethylene glycol (PEG)/salt type, namely PEG/phosphate, PEG/sulphate, and PEG/carbonate, were selected for this study. We observed fast motion of salty droplets dispersed in PEG continuous phase induced by electric field of relative low strength. Hence, three fluidic systems with separated electrode chambers for the evaluation of electrophoretic mobilities and for addressing experiments were fabricated. Electrophoretic mobilities of salty droplets always exceeded the value of \(1\times 10^{-7}\, \hbox {m}^2\hbox {V}^{-1}\hbox {s}^{-1}\), which is about by one magnitude higher value than those typically measured in water–oil droplet systems. The electrophoretic mobilities in systems with free surface are the same or even smaller than in closed microfluidic structures, which is accounted mainly to the fact that a significant part of salty droplets is exposed to air and does not contribute to droplet forcing. Series of addressing and merging experiments in a microfluidic chip shows that DC electric field can be used as a powerful tool for smart manipulation of droplets in microfluidic systems with PEG/salt ATPS.     

Reusable Cellulose‐Based Hydrogel Sticker Film Applied as Gate Dielectric in Paper Electrolyte‐Gated Transistors

A new concept for reusable eco‐friendly hydrogel electrolytes based on cellulose is introduced. The reported electrolytes are designed and engineered through a simple, fast, low‐cost, and eco‐friendly dissolution method of microcrystalline cellulose at low temperature using an aqueous LiOH/urea solvent system. The cellulose solution is combined with carboxymethyl cellulose, followed by the regeneration and simultaneous ion incorporation. The produced free standing cellulose‐based electrolyte films exhibit interesting properties for application in flexible electrochemical devices, such as biosensors or electrolyte‐gated transistors (EGTs), because of their high specific capacitances (4–5 µF cm^?2), transparency, and flexibility. Indium–gallium–zinc‐oxide EGTs on glass with laminated cellulose‐based hydrogel electrolytes (CHEs) as the gate dielectric are produced presenting a low working voltage (<2 V), showing an on–off current ratio (I _on/off) of 10⁶, a subthreshold swing lower than 0.2 V dec^?1, and saturation mobility (μ_Sat) reaching 26 cm² V^?1 s^?1. The flexible CHE‐gated transistors on paper are also demonstrated, which operate at switching frequencies up to 100 Hz. Combining the flexibility of the EGTs on paper with the reusability of the developed CHEs is a breakthrough toward biodegradable advanced functional materials allied with disposable/recyclable and low‐cost electronic devices.     

Low‐Temperature,Nontoxic Water‐Induced Metal‐Oxide Thin Films and Their Application in Thin‐Film Transistors

Here, a simple, nontoxic, and inexpensive “water‐inducement” technique for the fabrication of oxide thin films at low annealing temperatures is reported. For water‐induced (WI) precursor solution, the solvent is composed of water without additional organic additives and catalysts. The thermogravimetric analysis indicates that the annealing temperature can be lowered by prolonging the annealing time. A systematic study is carried out to reveal the annealing condition dependence on the performance of the thin‐film transistors (TFTs). The WI indium‐zinc oxide (IZO) TFT integrated on SiO₂ dielectric, annealed at 300 °C for 2 h, exhibits a saturation mobility of 3.35 cm² V^?1 s^?1 and an on‐to‐off current ratio of ≈10⁸. Interestingly, through prolonging the annealing time to 4 h, the electrical parameters of IZO TFTs annealed at 230 °C are comparable with the TFTs annealed at 300 °C. Finally, fully WI IZO TFT based on YO_x dielectric is integrated and investigated. This TFT device can be regarded as “green electronics” in a true sense, because no organic‐related additives are used during the whole device fabrication process. The as‐fabricated IZO/YO_x TFT exhibits excellent electron transport characteristics with low operating voltage (≈1.5 V), small subthreshold swing voltage of 65 mV dec^?1 and the mobility in excess of 25 cm² V^?1 s^?1.     

Water‐Induced Scandium Oxide Dielectric for Low‐Operating Voltage n‐ and p‐Type Metal‐Oxide Thin‐Film Transistors

Solution‐processed metal‐oxide thin films based on high dielectric constant (k) materials have been extensively studied for use in low‐cost and high‐performance thin‐film transistors (TFTs). Here, scandium oxide (ScO_x) is fabricated as a TFT dielectric with excellent electrical properties using a novel water‐inducement method. The thin films are annealed at various temperatures and characterized by using X‐ray diffraction, atomic‐force microscopy, X‐ray photoelectron spectroscopy, optical spectroscopy, and a series of electrical measurements. The optimized ScO_x thin film exhibits a low‐leakage current density of 0.2 nA cm^?2 at 2 MV cm^?1, a large areal capacitance of 460 nF cm^?2 at 20 Hz and a permittivity of 12.1. To verify the possible applications of ScO_x thin films as the gate dielectric in complementary metal oxide semiconductor (CMOS) electronics, they were integrated in both n‐type InZnO (IZO) and p‐type CuO TFTs for testing. The water‐induced full oxide IZO/ScO_x TFTs exhibit an excellent performance, including a high electron mobility of 27.7 cm² V^?1 s^?1, a large current ratio (I_on/I_off) of 2.7 × 10⁷ and high stability. Moreover, as far as we know it is the first time that solution‐processed p‐type oxide TFTs based on a high‐k dielectric are achieved. The as‐fabricated p‐type CuO/ScO_x TFTs exhibit a large I_on/I_off of around 10⁵ and a hole mobility of 0.8 cm² V^?1 at an operating voltage of 3 V. To the best of our knowledge, these electrical parameters are among the highest performances for solution‐processed p‐type TFTs, which represents a great step towards the achievement of low‐cost, all‐oxide, and low‐power consumption CMOS logics.     

Topographic Energy Management in Water Distribution Systems

A significant amount of energy is required to operate pressurised water distribution systems, and therefore, improving their efficiency is crucial. Traditionally, more emphasis has been placed on operational losses (pumping inefficiencies, excess leakage or friction in pipes) than on structural (or topographic) losses, which arise because of the irregular (unchangeable) terrain on which the system is located and the network’s layout. Hence, modifying the network to adopt an ecologically friendly layout is the only way to reduce structural losses. With the aim of improving the management of water distribution systems and optimising their energy use, this work audits and classifies water networks’ structural losses (derived from topographic energy), which constitutes the main novelty of this paper. Energy can be recovered with PATs (pumps as turbines) or removed through PRVs (pressure reducing valves). The proposed hydraulic analysis clarifies how that energy is used and identifies the most suitable strategy for improving efficiency as locating the most suitable place to install PRVs or PATs. Two examples are discussed to illustrate the relevance of this analysis.

     

Structural property of soybean lunasin and development of a method to quantify lunasin in plasma using an optimized immunoassay protocol

Lunasin is a 43-amino acid naturally occurring chemopreventive peptide with demonstrated anti-cancer and anti-inflammatory properties. The objectives of this study were to determine the effect of temperature on the secondary structure of lunasin, to develop a method of isolating lunasin from human plasma using an ion-exchange microspin column and to quantify the amount of lunasin using an optimized enzyme-linked immunosorbent assay. Lunasin was purified using a combination of ion-exchange chromatography, ultrafiltration and gel filtration chromatography. Circular dichroism showed that increased in temperature from 25 to 100 °C resulted in changes on the secondary structure of lunasin and its capability to interact with rabbit polyclonal antibody. Enzyme linked immunosorbent assay showed that lunasin rabbit polyclonal antibody has a titer of 250 and a specific activity of 0.05 mL/μg. A linear response was detected between 16 to 48 ng lunasin per mL (y = 0.03x − 0.38, R² = 0.96). The use of diethylaminoethyl microspin column to isolate spiked lunasin in human plasma showed that most lunasin (37.8–46.5%) bound to the column eluted with Tris–HCl buffer, pH 7.5 with a yield up to 76.6%. In conclusion, lunasin can be isolated from human plasma by a simple DEAE microspin column technique and can be quantified using a validated and optimized immunoassay procedure. This method can be used directly to quantify lunasin from plasma in different human and animal studies aiming to determine its bioavailability.     

On stationary heat conduction in 3D symmetric domains: an application of extended thermodynamics

In this paper, we study some three-dimensional stationary heat conduction problems in rarefied gases at rest, using the linearized 13-moment equations of extended thermodynamics. It follows that, in this linear theory, the temperature is still described by the Fourier law of heat conduction, while in contrast with the Navier–Stokes law, the stress tensor does not vanish. Furthermore, a non-equilibrium temperature is introduced and differences between this temperature and the kinetic one are predicted.     

Energy analysis of in-series biohydrogen and methane production from organic wastes

Biohydrogen production has been coupled in some cases to other energy production technologies in order to overcome its modest energy gains. Anaerobic digestion, when used for methane recovery, has long been regarded as an energy recovery technology. We determined the energy potential from the coupling of either semi-continuous or batch hydrogen lab-scale bioreactors to a methanogenic stage. All processes were performed in solid substrate fermentation mode using the organic fraction of municipal solid wastes as first fed.