This study presents a specific case of how a teacher in China learned to teach with problem posing through a collaborative, iterative design process with a researcher. Supported by a networked ...improvement community, at every step of the journey that they undertook, they partnered to design, deliver, and revise a mathematics lesson that fostered students’ learning through problem posing. A detailed travelogue of their journey serves to document what research on teaching through mathematical problem posing can look like and how the teacher learned to teach using this novel approach. We explore the utility of the 3H (head, heart, and hands) model as a powerful way to think about holistic, transformative teacher learning. In addition, we consider aspects of the networked improvement community in which the teacher–researcher partnership operated that enabled capacity for sustaining this kind of effort to change practice.
•This study follows a journey of a teacher and a researcher designing, delivering, and revising a problem-posing-based lesson.•Shows how research on teaching through mathematical problem posing can look when conducted by a teacher–researcher partnership in an NIC.•Discusses utility of the 3H (head, heart, and hands) model as a holistic tool to describe teachers' transformative learning.
The energy storage capacity of a material depends on the active-ion arrangement and electron transfer rate at the electrode−electrolyte interface. Overcoming the low power density issues of ...batteries, the pseudocapacitive electrode can be an excellent alternative to improve the power density of the full cell in Asymmetric Supercapacitors (ASCs) mode to make grid-scale energy storage and delivery feasible. Quantum dots (QDs) is another class of nanomaterial that exhibits unique optical and electrical properties due to the quantum confinement effect and shows high mobility of diffused ions due to nanoscale dimension resulting in a very high surface area. Anhydrous NiC2O4 QDs are envisaged here as a potential energy storage material partly because of the presence of planer oxalates anions (C2O42−) resulting in a quasi-zero 2d arrangement. Superior specific capacity equivalent to 227.5mAh/g (capacitance:1638 F/g) at 1A/g in the potential window of 0.5 V was observed for Anhydrous NiC2O4 QDs electrodes in an aqueous 2 M KOH electrolyte. The battery-type intercalative pseudocapacitance mechanism seems to operate behind the high charge storage capacity of anhydrous NiC2O4 QDs. Almost 22 % (surface controlled) and 78 % (diffusion-controlled intercalative) storage was observed for anhydrous NiC2O4 QDs electrodes. Further, in a full cell, asymmetric supercapacitors (ASCs) mode in which porous anhydrous NiC2O4 QDs are made as the positive electrode and Activated Carbon (AC) as the negative electrode, operating potential window 1.6 V, the highest specific energy of 292 Wh/kg at a specific power of ~772 W/kg and Even at a high power density of 2884 W/kg− at an energy density equivalence of 87 Wh/kg was obtained with high cyclic stability in aqueous 2 M KOH electrolyte. Even in neutral 1 M aqueous Na2SO4 electrolyte, and in the operating potential window 1.6 V, The highest specific energy of 126 Wh/kg and specific power of ~480 W/kg at 1 A/g current density was observed in 1 M Na2SO4 was obtained with high cyclic stability for NiC2O4 QDs full cell in ASCs mode.
•Intercalative charge storage seems to be operative behind high capacity of the Anhydrous NiC2O4 Quantum dot electrodes.•High surface area couples with porous structure of the NiC2O4 Quantum dot electrode are the reason behind fast diffusion of ions and supcapacitive performance of the electrode in full cell mode.•In full cell mode, where anhydrous NiC2O4 QDs are made as the positive electrode and Activated Carbon (AC) as the negative electrode, operating potential window 1.6 V, the highest specific energy of 292 Wh/kg at a specific power of ~772 W/kg was achieved for the cell.
A 1-plane graph is a graph embedded in the plane such that each edge is crossed at most once. A NIC-plane graph is a 1-plane graph such that any two pairs of crossing edges share at most one ...end-vertex. An edge partition of a 1-plane graph G is a coloring of the edges of G with two colors, red and blue, such that both the graph induced by the red edges and the graph induced by the blue edges are plane graphs. We prove the following: (i) Every NIC-plane graph admits an edge partition such that the red graph has maximum vertex degree three; this bound on the vertex degree is worst-case optimal. (ii) Deciding whether a NIC-plane graph admits an edge partition such that the red graph has maximum vertex degree two is NP-complete. (iii) Deciding whether a 1-plane graph admits an edge partition such that the red graph has maximum vertex degree one, and computing one in the positive case, can be done in quadratic time. Applications of these results to graph drawing are also discussed.
A smart portable sensor with ratio and dual-mode for in situ determination of nicotine (NIC) in tobacco leaves was reported. Activated screen-printed carbon electrode (SPCE) was used as a sensing ...platform. Paracetamol (PA) was used as a ratiometric reference. Current and potential dual-signal output was applied as dual-mode. The scanning electron microscope, energy dispersive spectroscopy, cyclic voltammetry, electrochemical impedance spectroscopy, square-wave voltammetry, and NIC morphological fitting and theoretical calculation were used to study the sensor. Under the amperometric mode, the linear range of NIC is 10-<inline-formula> <tex-math notation="LaTeX">800 ~\mu </tex-math></inline-formula>mol/L, and the detection limit is <inline-formula> <tex-math notation="LaTeX">1.72 ~\mu </tex-math></inline-formula>mol/L (S/N = 3). And under the potential mode, the linear range of NIC is 10-<inline-formula> <tex-math notation="LaTeX">500 ~\mu </tex-math></inline-formula>mol/L, and the detection limit is <inline-formula> <tex-math notation="LaTeX">0.02 ~\mu </tex-math></inline-formula>mol/L (S/N = 3). In addition, the proposed sensor has been applied to in situ determination of NIC in tobacco leaves with acceptable relative derivation ranging from 5.04% to 7.63% between the sensor and high-performance liquid chromatography.
The concept of a self-oscillating non-Foster unit cell, intended for use in future active metasurfaces, is introduced. It is based on two orthogonally polarized small antennas connected via a ...negative impedance converter (NIC). An NIC converts the admittance of the first antenna into a negative admittance, canceling the admittance of the second antenna within a theoretically infinite bandwidth. This system behaves as a special kind of a nearly perfectly matched small active antenna that supports oscillations at every frequency within NIC's operating bandwidth. Frequency tuning is achieved either by inclusion of a resonant circuit or by injection locking from an external source. The influence of NIC dispersion, non-linearity, and antenna type on the system performances is discussed, and appropriate design guidelines are given. Several scaled experimental demonstrators of non-Foster self-oscillating unit cell, operating in lower RF range, were designed, manufactured, and tested. The experimental results proved the correctness of the basic idea and showed stable self-oscillations with a tuning range from 1:2 to 1:3.
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