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Hydrogen dinitrate anion, HNO3 (NO3- ), is a proton-bound dimer with a very strong hydrogen bond. By employing ab initio molecular dynamics (AIMD) method, we studied the effects of the proton transfer and the rotation of the nitrates on the vibrational profiles of HNO3 (NO3- )(H2 O)n (n = 0-2). The AIMD results indicate that the structure of the n = 0 cluster is very flexible, even though its hydrogen bond is quite strong. Significant rotations around the hydrogen bond and frequent transfers of proton from HNO3 to NO3- are observed in AIMD simulations. Dynamic changes are therefore an important factor in understanding the broadening of vibrational features. For n = 1, the extent of structural fluctuation increases further, as H2 O could move around the anion while the HNO3 (NO3- ) core also goes through structural changes. Its vibrational spectrum can be understood as a mixture of many isomers visited during AIMD simulations. By n = 2, the structure is stabilized around one isomer, with the linker between the two nitrates being H5 O2+ , rather than H+ . Due to strong hydrogen bonds between nitrates and water molecules, this H5 O2+ takes the extraordinary structure with the H+ localized on one H2 O, rather than being shared. While this novel structure is stable during AIMD simulations, the dynamic fluctuations in hydrogen bond distances still produce significant broadening in its vibrational profile.

Porous curved polycyclic aromatic compounds 6 and 14 bearing a tribenzotriquinacene (TBTQ) core encircled by an m,p,p,m,m,p,p,m,m,p,p,m-cyclododecaphenylene belt were synthesized and characterized by NMR spectroscopy and mass spectrometry. These trefoil hydrocarbon macrocycles were constructed in high yield using an intramolecular threefold Scholl macrocyclization. X-ray crystal analysis of 14 demonstrated a large wizard-hat-shaped structure with three pores (radii 2.9-3.0 angstrom). The pi-stacking aggregation of the hexa-n-dodecyloxy derivative 6a and the chloride anion binding properties of 14 were studied by NMR spectroscopy. Such stacking and anion binding properties were much weaker in the singly 11 and doubly macrocyclized products 12.

Heatstroke is a devastating condition that is characterized by severe hyperthermia and central nervous system dysfunction. However, the mechanism of thermoregulatory center dysfunction of the hypothalamus in heatstroke is unclear. In this study, we established a heatstroke mouse model and a heat-stressed neuronal cellular model on the pheochromocytoma-12 (PC12) cell line. These models revealed that HS promoted obvious neuronal injury in the hypothalamus, with high pathological scores. In addition, PC12 cell apoptosis was evident by decreased cell viability, increased caspase-3 activity, and high apoptosis rates. Furthermore, 14 differentially expressed proteins in the hypothalamus were analyzed by fluorescence two-dimensional difference gel electrophoresis and identified by matrix-assisted laser desorption ionization time-of-flight mass spectrometry. Expression changes in hippocalcin (HPAC), a downregulated neuron-specific calcium-binding protein, were confirmed in the hypothalamus of the heatstroke mice and heat-stressed PC12 cells by immunochemistry and western blot. Moreover, HPAC overexpression and HPAC-targeted small interfering RNA experiments revealed that HPAC functioned as an antiapoptotic protein in heat-stressed PC12 cells and hypothalamic injury. Lastly, ulinastatin (UTI), a cell-protective drug that is clinically used to treat patients with heatstroke, was used in vitro and in vivo to confirm the role of HPAC; UTI inhibited heat stress (HS)-induced downregulation of HPAC expression, protected hypothalamic neurons and PC12 cells from HS-induced apoptosis and increased heat tolerance in the heatstroke animals. In summary, our study has uncovered and demonstrated the protective role of HPAC in heatstroke-induced hypothalamic injury in mice.

This study presents a new type of negatively curved nanographene (C86 H32 ) that contains an unprecedented pattern of heptagons. A tert-butylated derivative of C86 H32 was successfully synthesized using tetrabenzodipleiadiene as a key building block. This synthesis involved a ring expansion reaction as a key step to form the seven-membered rings in the framework of tetrabenzodipleiadiene. The single-crystal structure reveals a saddle-shaped molecule with a highly bent naphthalene moiety at the center of the polycyclic backbone. As found from the DFT calculations, this aromatic saddle is flexible at room temperature and has a saddle-shaped geometry as the dominant conformation. The DFT calculations along with experimental results show that the attachment of t-butyl groups to the central tetrabenzodipleiadiene moiety of nanographene C86 H32 can stabilize the saddle conformation and make this nanographene less flexible.

The finite analytic method is developed to solve the two-dimensional steady fluid flows in heterogeneous porous media with full tensor permeability on unstructured grids. The proposed FAM is constructed based upon the power-law analytic nodal solution in the angular domain with arbitrary shape. When approaching the grid node joining the subdomains, three different flow patterns may exist: power-law flow, linear flow or the stagnant flow. Based on the nodal analytic solution, the triangle-based FAM is proposed. Numerical examples show that the proposed numerical scheme makes the convergences much quickly than the traditional methods, typically the weighted harmonic mean method under the cell refinement. In practical applications, the grid refinement parameter n=2 or n=3 is recommended, and the relative error of the calculated equivalent permeability will below 4% independent of the heterogeneity. In contrast, when using the traditional numerical scheme the refinement ratio for the grid cell needs to increase dramatically to get an accurate result, especially for strong heterogeneous porous medium.

Herein we report synthesis, structure and properties of a new type of twisted nanographene, which contains an [8]circulene moiety in a polycyclic framework of 96 sp2 carbon atoms. The key steps in this synthesis are the Diels-Alder reaction of a macrocyclic diyne and the subsequent Scholl reaction forming the [8]circulene moiety. Two incompletely cyclized products were isolated from the Scholl reaction, providing insight into the cyclization of the strained octagon. This nanographene is twisted along two directions with end-to-end twists of 142.4° and 140.2° as revealed by X-ray crystallography, and is flexible at room temperature as found from the computational and experimental studies.

The finite analytic numerical method for 3D quasi-Laplace equation with conductivity in full tensor form is constructed in this article. For cubic grid system, the gradient of the potential variable will diverge when tending to the common edge joining the four grids with different conductivities. However, the potential gradient along the tangential direction is of limited value. As a consequence, the 3D quasi-Laplace equations will behave as a quasi-2D one. An approximate analytical solution of the 3D quasi-Laplace equation can be found around the common edge, which is expressed as a combination of a power-law function and a linear function. With the help of this approximate analytical solution, a 3D finite analytical numerical scheme is then constructed. Numerical examples show that the proposed numerical scheme can provide rather accurate solutions only with 3 × 3 × 3 or 4 × 4 × 4 subdivisions. More important, the convergent speed of the numerical scheme is independent of the conductivity heterogeneity. In contrast, when using the traditional numerical schemes, typically such as the MPFA method, the refinement ratio for the grid cell needs to increase dramatically to get an accurate result for the strong heterogeneous case.© 2017 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2017

Herein, we report two new types of twisted polycyclic arenes (2 a, b and 3 a, b) with constitutionally isomeric π-backbones, which are synthesized by controlling the Scholl reaction of 1,2,4,5-tetra(naphth-2-yl)-3,6-diphenylbenzene (1) with properly positioned electron-donating substituents. With a polycyclic backbone containing two [5]helicene and four [4]helicene moieties, 2 a and b are new members of multiple helicenes with interesting stereochemistries. The as-synthesized 2 a and b are the twisted isomers, and thermal isomerization of twisted-2 b results in anti-2 b, a more stable stereoisomer. Both twisted- and anti-2 b have been fully characterized, and the thermal isomerization of twisted-2 b has been studied with 1H NMR spectroscopy and DFT calculations. Compounds 3 a and b are new members of twistacenes, the benzannulated pentacene backbone of which exhibits an end-to-end twist as found from the crystal structure. Twisted- and anti-2 b are also found to function as p-type semiconductors in solution-processed thin film transistors, whereas the thin films of 3 b appear insulating presumably due to the lack of π–π interactions.

A typical power series analytic solution of quasi-Laplace equation in the infinitesimal angle domain around the singular point of the square cells is provided in this article. Toward the singular point, the gradient of the potential variable will tend to infinity, which is described by the first term of the power series solution. Based on this analytic solution, three finite analytic numerical methods are proposed. These methods are analogous and are constructed, respectively, when considering different numbers of the terms or using different schemes to determine the relevant parameters in the power series. Numerical examples show that all of the three finite analytic numerical methods proposed can provide rather accurate solutions than the traditional numerical methods. In contrast, when using the traditional numerical schemes to solve the quasi-Laplace equation in a strong heterogeneous medium, the refinement ratio for the grid cell needs to increase dramatically to get an accurate result. In practical applications, subdividing each origin cell into 2 × 2 or 3 × 3 subcells is enough for the finite analytical numerical methods to get relatively accurate results. The finite analytical numerical methods are also convenient to construct the flux field with high accuracy.© 2014 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 30: 1755–1769, 2014

Introduction An important recent trend in education has been towards the integration of different technologies, such as digital games (Chen, Chen & Liu, 2010; Chiang, Lin, Cheng & Liu, 2011; Lee & Chen, 2009; Lin & Liu, 2009; Liu & Lin, 2009) and educational robots (Chang, Lee, Chao, Wang & Chen, 2010a; Chang, Lee, Wang & Chen, 2010b; Wei, Hung, Lee & Chen, 2011), and the learning and teaching about design and implementation of educational robots (Liu, Lin & Chang, 2010). The development of educational robots, such as Topobo and LEGO Mindstorms NXT, gives students more chances to learning to build their own robots (Feng, Lin & Liu, 2011; Liu, 2010). Liu (2010) found that students perceived that educational robots were a useful learning technology and considered that learning to construct robots could help them develop important technological skills. Many researchers investigated the effect of integrating educational robots into educational fields, and they found that educational robots not only can enhance students’ learning motivation (Chang et al, 2010a; Liu et al, 2010) but also can improve students’ learning (Chang et al, 2010b). The findings from past studies showed that educational robots have become an important learning technology and a subject for students to study. The support and confidence of parents to help their children to learn with or learn to build robots are important for promoting the use of educational robots. The previous study (Liu, 2010) explored the students’ perceptions of educational robots, but the further investigation of parents’ perceptions towards educational robots has been lacking.

Eric Zhi Feng Liu is an associate professor of Graduate Institute of Learning and Instruction at National Central University, Taiwan. His research addresses Web 2.0 and education, robotics education, and edutainment. Ru Chu Shih is an assistant professor of Department of Modern Languages, National Pingtung University of Science and Technology, Taiwan. His research addresses Web 2.0 and language learning. Yuan Lung Tsai is a lecturer of General Education Center, Toko University, Taiwan. His research addresses Web 2.0 and education. Address for correspondence: Dr. Eric Zhi Feng Liu, Graduate Institute of Learning & Instruction, National Central University, No.300 Jung-da Road, Chung-Li City, Taoyuan, Taiwan 320. Email: totem@cc.ncu.edu.tw

Addressforcorrespondence:Mr.YuLiangChen,Departmentof ComputerScience,NationalChiaoTungUniversity,1001 University Road, Hsinchu 300, Taiwan. Email: imklchen@gmail.com; Dr. Eric Zhi Feng Liu, GraduateInstitute of Learning & Instruction, National Central University, no. 300 Jung-da Road, Chung-Li City, Taoyuan320, Taiwan. Email: totem@cc.ncu.edu.tw

This article considers the efficacy of educational computer and video games in improving student motivation and achievement. It is stated that prior research has suggested that educational games provide positive opportunities for active learning and help develop learning skills. A content analysis approach is used to analyze 196 different games that are popular in Taiwan. A Delphi survey is given to six educational technology experts, six educational psychology experts, six game design experts, six students each from elementary, junior, and high schools, and six teachers in an attempt to reach a consensus on educational games.

The article focuses on the relationship between peer feedback, cognitive and metacognitive strategies, and achievement in networked peer assessment. The results of a regression analysis revealed a significant relationship between the use of cognitive and metacognitive strategies in feedback and in students' own achievement under networked peer assessment. The results indicated that students' use of advanced level cognitive and metacognitive strategies was a positive and significant predictor of their own achievements.

The article attempts to utilize a network to establish a personal and group-based learning portfolio system characterized by cooperative learning. The system should be user-friendly and useful to teachers as they instruct and evaluate students and document and evaluate student and group learning portfolios. The personal and group-based learning portfolio system comprises two types of users: the teacher, who gives assignments and divides students into groups, and the students, who are asked to become acquainted with their group members, to collaborate to complete projects, and to evaluate the assignments of other groups.

This study used aptitude treatment interaction design to examine how feedback formats (specific vs. holistic) and executive thinking styles (high vs. low) affect web-based peer assessment. An Internet-based (anonymous) peer-assessment system was developed and used by 58 computer science students who submitted assignments for peer review. The results indicated that while students with high executive thinking styles significantly improved over two rounds of peer assessment, low executive students did not improve through the cycles. In addition, high executive students contributed substantially better feedback than their low executive counterparts. In the second round of peer assessment, thinking style and feedback format interactively affected student learning. Low executive students receiving specific feedback significantly outperformed those receiving holistic feedback. In receiving holistic feedback, high executive thinkers outperformed their low executive counterparts. This study suggests that future web-based peer assessment adopts a specific feedback format for all students.

We report computational studies on Al+(H2O)n, n = 6−9, and HAlOH+(H2O)n-1, n = 6−14, by the density functional theory based ab initio molecular dynamics method, employing a planewave basis set with pseudopotentials, and also by conventional methods with Gaussian basis sets. The mechanism for the intracluster H2 elimination reaction is explored. First, a new size-dependent insertion reaction for the transformation of Al+(H2O)n into HAlOH+(H2O)n-1 is discovered for n ≥ 8. This is because of the presence of a fairly stable six-water-ring structure in Al+(H2O)n with 12 members, including the Al+. This structure promotes acidic dissociation and, for n ≥ 8, leads to the insertion reaction. Gaussian based BPW91 and MP2 calculations with 6-31G* and 6-31G** basis sets confirmed the existence of such structures and located the transition structures for the insertion reaction. The calculated transition barrier is 10.0 kcal/mol for n = 9 and 7.1 kcal/mol for n = 8 at the MP2/6-31G** level, with zero-point energy corr...

The mechanism of size-dependent intracluster hydrogen loss in the cluster ions Mg + (H 2 O) n , which is switched on around n = 6, and off around n = 14, was studied by ab initio calculations at the MP2/6-31G* and MP2/6-31G** levels for n = 1-6. The reaction proceeds by Mg + -assisted breaking of an H-O bond in one of the H 2 O molecules. The reaction barrier is dependent on both the cluster size and the solvation structure. As n increases from 1 to 6, there is a dramatic drop in the reaction barrier, from greater than 70 kcal mol - 1 for n = 1 to less than 10 kcal mol - 1 for n = 6. In the transition structures, the Mg atom is close to the oxidation state of +2, and H 2 O molecules in the first solvation shell are much more effective in stabilizing the transition structures and lowering the reaction barriers than H 2 O molecules in the other solvation shells. While the reaction barrier for trimer core structures with only three H 2 O molecules in the first shell is greater than 24 kcal mol - 1 , even for Mg + (H 2 O) 6 , it drops considerably for clusters with four-six H 2 O molecules in the first shell. The more highly coordinated complexes have comparable or slightly higher energy than the trimer core structures, and the presence of such high coordination number complexes is the underlying kinetic factor for the switching on of the hydrogen-loss reaction around n=6. For clusters with trimer core structures, the hydrogen loss reaction is much easier when it is preceded by an isomerization step that increases the coordination number around Mg + . Delocalization of the electron on the singly occupied molecular orbital (SOMO) away from the Mg + ion is observed for the hexamer core structure, while at the same time this isomer is the most reactive for the hydrogen-loss reaction, with an energy barrier of only 2.7 kcal mol - 1 at the MP2/6-31G** level.