As an infused or a separated theme? Chinese science teacher educators' conceptions of incorporating Nature of Science instruction in the courses of training pre-service science teachers

ABSTRACT: Teaching nature of science (NOS) is beginning to find its place in science education in China. This exploratory study interviewed twenty-four Chinese science teacher educators about their conceptions of teaching NOS to preservice science teachers. Although five dimensions emerged, this paper mainly focuses on reporting the findings relevant to one dimension, i.e., incorporating NOS instruction in the courses of training pre-service science teachers. There were two preferences: twelve out of the twenty-four educators preferred having NOS instruction infused into the teaching of various course components, including inquiry-based science teaching approach, history of science, science subject content, and school science textbook analysis. The others chose to have a separated NOS module in their courses, though they indicated NOS might be also touched upon in other course components. It was found that three factors influenced their preference; the textbooks currently used by Chinese science teacher educators to train pre-service science teachers, their views of NOS content to be taught, and their vision of teaching NOS. We argue that the findings in this study provide some hints on ways to encourage science teacher educators to give higher priority to NOS instruction in their courses, which is believed necessary for achieving the goal of developing public’s scientific literacy.published_or_final_versio

catena-poly[di-μ(2)-chloro(1,10-phenanthroline)cadmium(II)]

The crystal structure of the 1/1 adduct of cadmium dichloride with 1,10-phenanthroline, [CdCl2(C12H8N2)](n), is based on an infinite chain of Cd2Cl2 parallelograms sharing their Cd corners. The chain propagates in a zigzag manner along the c axis of the monoclinic unit cell. The Cd atom and the phenanthroline molecule both lie on special positions of 2 symmetry

Peroxomolybdate(VI)-citrate and -malate complex interconversions by pH-dependence Synthetic, structural and spectroscopic studies

The reaction of potassium molybdate(vi) with biologically relevant ligands, citric and malic acids, in the presence of H2O2 was investigated for the effect of pH variations on the product pattern. That with citric acid led to the formation of the monomeric complex K-4[MoO(O-2)(2)(cit)].4H(2)O (1) in the pH range 7-9, and dimer K-5[MoO(O-2)(2)(Hcit)H(Hcit)(O-2)(2)OMo].6H(2)O (2) (H(4)cit = citric acid) at pH 3-6 through carboxylate-carboxylic acid hydrogen bonding. The relation with the previously identified K-4[MoO3(cit)].2H(2)O (4) and K-4[Mo2O5(Hcit)(2)].4H(2)O (5) were shown. These and other intermediates were shown to react in the pH range 3-6 to give a more stable species 2; the reaction sequence was demonstrated either by the protonation from 1 or the deprotonation of [MoO(O-2)(2)(H(2)cit)](2-)(8). Evidence that 2 exists as a dimer in solution is presented. The reaction with (S)-malic acid afforded Delta-K-2n[MoO(O-2)(2)((S)-Hmal)](n).nH(2)O (3) (H(3)mal = malic acid) that was oxidized further to oxalato molybdate (11) by H2O2. The three complexes 1-3 were characterized by elemental analysis, UV, IR and NMR spectroscopies, in addition to the X-ray structural studies that show citrate and malate being coordinated as bidentate ligands via alpha-alkoxyl and alpha-carboxylate groups. The formation of these complexes is dictated by pH and their thermal stabilities varied with the coordinated hydroxycarboxylate ligands

Down-regulated CK8 expression in human intervertebral disc degeneration

As an intermediate filament protein, cytokeratin 8 (CK8) exerts multiple cellular functions. Moreover, it has been identified as a marker of notochord cells, which play essential roles in human nucleus pulposus (NP). However, the distribution of CK8 positive cells in human NP and their relationship with intervertebral disc degeneration (IDD) have not been clarified until now. Here, we found the percentage of CK8 positive cells in IDD (25.7+/-4.14%) was significantly lower than that in normal and scoliosis NP (51.9+/-9.73% and 47.8+/-5.51%, respectively, p<0.05). Western blotting and qRT-PCR results confirmed the down-regulation of CK8 expression in IDD on both of protein and mRNA levels. Furthermore, approximately 37.4% of cell clusters were CK8 positive in IDD. Taken together, this is the first study to show a down-regulated CK8 expression and the percentage of CK8 positive cell clusters in IDD based upon multiple lines of evidence. Consequently, CK8 positive cells might be considered as a potential option in the development of cellular treatment strategies for NP repair.published_or_final_versio

Alkali metal emissions in early stage of a pulverized-coal flame: DNS analysis of reacting layers and chemistry tabulation

The intricate coupling between coal pyrolysis, gas phase combustion and the emissions of alkali metal, such as sodium, is studied in early stage of a temporally evolving three-dimensional planar turbulent jet carrying pulverized-coal particles. Complex chemistry is used to account for both the combustion of volatile hydrocarbons and the sodium containing species. The response of the sodium chemistry is analyzed in the mixture fraction space, along with the topology of the reactions zones. Combustion is found to start preferentially in partially premixed flames, which then evolve toward di usion-like reactive layers and reach chemical equilibrium. From the direct numerical simulation (DNS) database, the possibility of modeling the dynamics of sodium species using one-dimensional premixed flamelet generated manifolds (FGM) is investigated. A chemical lookup table is constructed for the combustion of the partially premixed volatiles and an additional three-dimensional simulation is performed to compare the tabulated sodium species against their reference counterparts with complex chemistry. Quantitative analysis of the performance of the developed chemistry tabulation confirms the validity of the approach. Perspectives for the modeling of sodium emissions in pulverized-coal furnaces and boilers are finally drawn.National Natural Science Foundation of China and China Postdoctoral Science Foundatio

Ultra-strong Adhesion of Graphene Membranes

As mechanical structures enter the nanoscale regime, the influence of van der Waals forces increases. Graphene is attractive for nanomechanical systems because its Young's modulus and strength are both intrinsically high, but the mechanical behavior of graphene is also strongly influenced by the van der Waals force. For example, this force clamps graphene samples to substrates, and also holds together the individual graphene sheets in multilayer samples. Here we use a pressurized blister test to directly measure the adhesion energy of graphene sheets with a silicon oxide substrate. We find an adhesion energy of 0.45 \pm 0.02 J/m2 for monolayer graphene and 0.31 \pm 0.03 J/m2 for samples containing 2-5 graphene sheets. These values are larger than the adhesion energies measured in typical micromechanical structures and are comparable to solid/liquid adhesion energies. We attribute this to the extreme flexibility of graphene, which allows it to conform to the topography of even the smoothest substrates, thus making its interaction with the substrate more liquid-like than solid-like.Comment: to appear in Nature Nanotechnolog

Long-standing Small-scale Reconnection Processes at Saturn Revealed by Cassini

The internal mass source from the icy moon Enceladus in Saturn’s rapidly rotating magnetosphere drives electromagnetic dynamics in multiple spatial and temporal scales. The distribution and circulation of the internal plasma and associated energy are thus crucial in understanding Saturn’s magnetospheric environment. Magnetic reconnection is one of the key processes in driving plasma and energy transport in the magnetosphere, and also a fundamental plasma process in energizing charged particles. Recent works suggested that reconnection driven by Saturn’s rapid rotation might appear as a chain of microscale structures, named drizzle-like reconnection. The drizzle-like reconnection could exist not only in the nightside magnetodisk, but also in the dayside magnetodisk. Here, using in situ measurements from the Cassini spacecraft, we report multiple reconnection sites that were successively detected during a time interval longer than one rotation period. The time separation between two adjacently detected reconnection sites can be much less than one rotation period, implying that the reconnection processes are likely small-scale, or frequently repetitive. The spatial distribution of the identified long-standing multiple small reconnection site sequences shows no significant preference on local times. We propose that the small reconnection sites discussed in this Letter are rotationally driven and rotate with the magnetosphere. Since the reconnection process on Saturn can be long-durational, the rotational regime can cause these smallscale reconnection sites to spread to all local times, resulting in global release of energy and mass from the magnetosphere

Synthesis, spectroscopic properties and structural characterization of sodium potassium citrato oxotungstate(VI) dimer

The sodium-potassium citrate oxotungstate(VI) dimer, Na4K2[W2O5-(cit)(2)]. 11H(2)O (H(4)cit = citric acid) was obtained by the reaction of sodium tungstate (VI) and excess potassium citrate monobasic (KH(3)cit) in neutral solution. The crystal data for the title compound: monoclinic, C12H30K2Na4W2O30, M-r = 1192. 21, space group P2(1)/n, a = 17.427(4), b = 10.022(2), c = 18.631(3) Angstrom, beta = 92.62(1)degrees, V = 3252 (2) Angstrom(3), Z = 4, D-c = 2.435 g/cm(3), mu(MoK alpha) = 76.38 cm(-1), F (000) = 2288. The structure was refined to R = 0.0434 for 6327 independent observed reflections with I>3 sigma(I). The complex anion contains a quasi-centrosymmetric (O2W)O-b(WO2) core with a bent bridging oxo group [W-O-b-W 175. 0(4)degrees]. Each citrate as tridentate ligand coordinates to a tungsten atom through the alkoxy, alpha-carboxyl, and one beta-carboxyl group, while the other P-carboxyl group remains uncoordinated. Principal dimensions are: W-O-b 1. 883(6) Angstrom, (W = O-t)av 1.715(6) Angstrom, W-O (alkoxy) 1.959 (6) Angstrom, W-O (alpha-carboxy) 2. 176(6) Angstrom and W-O (beta-carboxy) 2. 231(6) Angstrom. The tungsten atom is located in a distorted-octahedron environment

Demonology of China and Russia as the Basis of Image Bases for Artificial Intelligence Technologies

The aim of the study is to identify the basic ontological differences in the folklore of Chinese and Russian cultures. We analyze these differences on the material of the demonological pantheon from Chinese and Russian fairy tales, myths and traditions. The analyzed demonological characters represent a separate semiotic system marking the most diverse manifestations of everyday life.Целью исследования является выявление базовых онтологических отличий в фольклорных произведениях китайской и русской культур. Данные отличия мы анализируем на материале демонологического пантеона из китайских и русских сказок, мифов и преданий. Проанализированные демонологические персонажи представляют собой отдельную семиотическую систему, маркирующую самые разные проявления повседневности