Activating argumentation schema to write argumentatively and tactfully.

To argue tactfully is a goal in argumentative writing, which entails balanced argumentation schema. Although computer-supported collaborative learning (CSCL) has been widely acknowledged as language learning mediation, especially in writing, few studies investigate its effectiveness in activating the balanced argumentation schema. This study explores the effectiveness of QQ group discussion, a kind of CSCL mediation most popular in China, in argumentative writing by means of quasi-experiment and interview. Fifty-six second-year college students in an English Department participated in this study. The experimental group were asked to have a pre-writing QQ group discussion on a disputable topic while the control group had an in-class face-to-face discussion (a regular teaching method for English majors). Content analysis of the essays was made to investigate the use of Counterargument elements, Qualifier and Concession. The results show that the two groups had no difference in the use of Counterargument-claim and Rebuttal. However, the experimental group surpassed the control group in Counterargument-data, Concession and Qualifier, which signifies more argumentativeness and tactfulness. In the delayed post-test this group still performed better. The interview transcriptions were coded and analyzed by inductive content analysis with the functions of QQ discussion as the themes. The result not only supported that of the experiment, but also revealed why and how QQ mediation could help activate the balanced argumentation schema. It is suggested that CSCL mediation should be promoted in argumentative writing instruction so that the students could write argumentatively and tactfully.

Fostering regulatory processes using computational scaffolding.

The use of computational scaffolding is a crucial strategy to foster students' regulation of learning skills, which is associated with increased learning achievement. However, most interventions treat the regulatory processes as individual actions isolated from a social context. This view contradicts the most recent research that points to the importance of studying the regulatory phenomenon from a social-cognitive perspective, where students' interactions influence their regulation of the learning process. This work explores these problems and presents multiple scaffolds to promote Self-regulation of Learning (SRL), co-regulation, and socially shared regulation of learning (SSRL) embedded within a computer-supported collaborative learning environment. A single-blind randomized controlled trial was performed with students (n = 71) enrolled in an online introductory programming course. Students were randomly assigned to three groups: 1) SRL-only support, 2) SRL, co-regulation, and SSRL support, and 3) a no support control group. The findings revealed that students who received regulatory support achieved higher course grades than the control group. However, only students who received SSRL and co-regulation support achieved superior performance in collaborative activities, confirming the importance of this type of regulation. Even though students did not increase in SRL aptitude, the intervention provided support for achieving higher grades in the course.

Comparison of three AUC techniques for the determination of the loading status and capsid titer of AAVs.

Due to the rise of adeno-associated viruses (AAVs) as gene therapy delivery vectors, boundary sedimentation velocity analytical ultracentrifugation (boundary SV-AUC) has been developed into a widely used quality control assay even for release analytics. It can be considered as the "gold standard" for the determination of the loading status of empty, partially filled, and full capsids especially when conducted in multiwavelength (MWL) mode. It can be considered to provide the most accurate determination of the loading status, and it also provides information on the capsid titer, aggregates, and potential contaminants such as free DNA. MWL boundary SV-AUC can be regarded as a multi-attribute (MAM) method for the characterization of AAVs. One major drawback of the method is the high sample consumption both in terms of concentration and volume. Here, we compare two alternative AUC techniques, band SV-AUC and analytical CsCl density gradient sedimentation equilibrium AUC (CsCl SE-AUC) with the boundary SV-AUC and the MWL-SV-AUC experiment. Our data show a high consistency of the determined full/empty ratios between these techniques if the appropriate wavelengths and extinction coefficients are used.

A Historical Review of Collaborative Learning and Cooperative Learning.

Collaborative learning and cooperative learning are two separate approaches developed independently by two groups of scholars around the same period of time in the 1960 and 1970 s. Due to their different origins and intertwined paths of development, they have their own distinct features while sharing many similarities. The relationship between collaborative learning and cooperative learning can be confusing. Therefore, this paper provides a brief historical review of collaborative learning and cooperative learning to identify the origins of each, where they diverge from each other, and where they are aligned. This paper examines the definitions of the two terms and compares their characteristics. This is followed by a discussion of their historical development in the last fifty years: early development between the 1960 and 1970 s; maturation in the 1980 and 1990 s; convergence in the mid-1990s; and the emergence of Computer-Supported Collaborative Learning (CSCL) in the late 1980s. Finally, this paper summarizes the four paradigms of mainstream research on collaborative and cooperative learning, namely, the "effect" paradigm, the "conditions" paradigm, the "interaction" paradigm, and the "design" paradigm.

Improvements in Efficiency and Stability of Perovskite Solar Cells Using a Cesium Chloride Additive.

Perovskite films with few defects play a key role in preparing high-performance perovskite solar cells (PSCs). Here, cesium chloride (CsCl) was introduced as a modulator into a perovskite precursor for manipulating the crystallization of perovskite films. By introducing CsCl, dense homogeneous perovskite films with high crystallinity, preferential orientation, and a pure black perovskite phase were prepared. In addition, the carrier lifetime of perovskite films was significantly increased because of the suppressed nonradiative recombination. Correspondingly, the power conversion efficiency (PCE) of small-area devices using CsCl regulation was increased from 20.56 to 22.86%. The 1 cm2 PSCs present a PCE of 21.53%, demonstrating their reliability for mass production. Furthermore, the device showed excellent stability maintaining 93.8% of its initial PCE after 500 h of continuous irradiation. Also, 95.3% of its PCE was kept after storage in ambient air for 2100 h. This study demonstrates that CsCl doping is a reliable way to prepare PSCs for practical applications.

Laser decontamination microscopic process study on radioactive contaminations with Cs+ ion of 304 stainless steel surface.

The decommissioning of contaminated metal equipment in nuclear facilities may produce a wide range of radioactive waste. For metallic equipment like the primary loop, the radioactivity is mainly located in the oxide surface. Laser decontamination was performed on 304 stainless steel specimens with a stable isotope Cs contamination layer. Laser melting was used to create oxide layer on the surface of polished specimen for enhancing the penetration of Cs+ ion. The interaction between laser and matter (contamination, oxide and substrate) was studied by the stratification theory considering the difference in the thickness of contamination layer. At higher pulse duration (τp = 5ns), laser decontamination is mainly caused by thermal effects. The metal near oxide layer melts and vaporizes to form a molten pool and crater. For short pulse duration (τp = 1ns), the removal of surface contaminations mainly depends on thermal effect and stress wave, CsCl particles were removed by vaporization; however, oxide layer was stripped from the substrate in the form of solid fragment. For ultra-short pulse duration (τp = 150ps), the oxide layer has been partially ablated. Most of the heat absorbed by γ (austenite) is used for heating and evaporation to form porous structure, while the great mass of heat absorbed by M (martensite) is used for thermal diffusion. Therefore, the M regions only form a dynamic molten pool on its surface without vaporization.

Resolving Salt-Induced Agglomeration of Laponite Suspensions Using X-ray Photon Correlation Spectroscopy and Molecular Dynamics Simulations.

Linking the physics of the relaxation behavior of viscoelastic fluids as they form arrested gel states to the underlying chemical changes is essential for developing predictive controls on the properties of the suspensions. In this study, 3 wt.% laponite suspensions are studied as model systems to probe the influence of salt-induced relaxation behavior arising from the assembly of laponite nanodisks. X-ray Photon Correlation Spectroscopy (XPCS) measurements show that laponite suspensions prepared in the presence of 5 mM concentrations of CaCl2, MgCl2 and CsCl salts accelerate the formation of arrested gel states, with CaCl2 having a significant impact followed by CsCl and MgCl2 salts. The competing effects of ion size and charge on relaxation behavior are noted. For example, the relaxation times of laponite suspensions in the presence of Mg2+ ions are slower compared to Cs+ ions despite the higher charge, suggesting that cation size dominates in this scenario. The faster relaxation behavior of laponite suspensions in the presence of Ca2+ ions compared to Cs+ ions shows that a higher charge dominates the size of the ion. The trends in relaxation behavior are consistent with the cluster formation behavior of laponite suspensions and the electrostatic interactions predicted from MD simulations. Charge balance is achieved by the intercalation of the cations at the negatively charged surfaces of laponite suspensions. These studies show that the arrested gel state of laponite suspensions is accelerated in the presence of salts, with ion sizes and charges having a competing effect on relaxation behavior.

Standard Bacteriophage Purification Procedures Cause Loss in Numbers and Activity.

For decades, bacteriophage purification has followed structured protocols focused on generating high concentrations of phage in manageable volumes. As research moves toward understanding complex phage populations, purification needs have shifted to maximize the amount of phage while maintaining diversity and activity. The effects of standard phage purification procedures such as polyethylene glycol (PEG) precipitation and cesium chloride (CsCl) density gradients on both diversity and activity of a phage population are not known. We have examined the effects of PEG precipitation and CsCl density gradients on a number of known phage (M13, T4, and ΦX 174) of varying structure and size, individually and as mixed sample. Measurement of phage numbers and activity throughout the purification process was performed. We demonstrate that these methods, used routinely to generate "pure" phage samples, are in fact detrimental to retention of phage number and activity; even more so in mixed phage samples. As such, minimal amounts of processing are recommended to introduce less bias and maintain more of a phage population.

Lab-Scale Production of Recombinant Adeno-Associated Viruses (AAV) for Expression of Optogenetic Elements.

Optogenetics, that is, the use of photoswitchable/-activatable moieties to precisely control or monitor the activity of cells and genes at unprecedented spatiotemporal resolution, holds tremendous promise for a wide array of applications in fundamental and clinical research. To fully realize and harness this potential, the availability of gene transfer vehicles ("vectors") that are easily produced and that allow to deliver the essential components to desired target cells in an efficient manner is key. For in vivo applications, it is, moreover, important that these vectors exhibit a high degree of cell specificity in order to reduce the risk of adverse side effects in off-targets and to minimize manufacturing costs. Here, we describe a set of basic protocols for the cloning, production, purification, and quality control of a particular vector that can fulfill all these requirements, that is, recombinant adeno-associated viruses (AAV). The latter are very attractive owing to their apathogenicity, their compatibility with the lowest biosafety level 1 conditions, their occurrence in multiple natural variants with distinct properties, and their exceptional amenability to engineering of the viral capsid and genome. The specific procedures reported here complement alternative protocols for AAV production described by others and us before, and, together, should enable any laboratory to generate these vectors on a small-to-medium scale for ex vivo or in vivo expression of optogenetic elements.

An Improved Leaf Protoplast System for Highly Efficient Transient Expression in Switchgrass (Panicum virgatum L.).

As a robust perennial C4-type monocot plant and a native species to North America, switchgrass (Panicum virgatum) has been evaluated and designated as a strong candidate bioenergy crop by the U.S. DOE. Although genetic modifications of switchgrass have been used to successfully reduce the recalcitrance of switchgrass biomass for biofuel production, the generation of transgenic switchgrass is still a slow and laborious process. A transient protoplast system can provide an excellent platform to accelerate the selection of genes-of-interest for tailoring switchgrass biomass. However, partially due to the lack of the complete genomic information, the attempts to optimize the transient protoplast system for switchgrass remain scarce. In this chapter, we provide an improved protocol for switchgrass protoplast isolation, increased transformation efficiency using CsCl gradient ultracentrifugation-derived plasmid DNA and extended application of the transient switchgrass protoplast system to analyze protein expression using western blot.

Utilizing Interactive Surfaces to Enhance Learning, Collaboration and Engagement: Insights from Learners' Gaze and Speech.

Interactive displays are becoming increasingly popular in informal learning environments as an educational technology for improving students' learning and enhancing their engagement. Interactive displays have the potential to reinforce and maintain collaboration and rich-interaction with the content in a natural and engaging manner. Despite the increased prevalence of interactive displays for learning, there is limited knowledge about how students collaborate in informal settings and how their collaboration around the interactive surfaces influences their learning and engagement. We present a dual eye-tracking study, involving 36 participants, a two-staged within-group experiment was conducted following single-group time series design, involving repeated measurement of participants' gaze, voice, game-logs and learning gain tests. Various correlation, regression and covariance analyses employed to investigate students' collaboration, engagement and learning gains during the activity. The results show that collaboratively, pairs who have high gaze similarity have high learning outcomes. Individually, participants spending high proportions of time in acquiring the complementary information from images and textual parts of the learning material attain high learning outcomes. Moreover, the results show that the speech could be an interesting covariate while analyzing the relation between the gaze variables and the learning gains (and task-based performance). We also show that the gaze is an effective proxy to cognitive mechanisms underlying collaboration not only in formal settings but also in informal learning scenarios.

Novel topological nodal lines and exotic drum-head-like surface states in synthesized CsCl-type binary alloy TiOs.

Very recently, searching for new topological nodal line semimetals (TNLSs) and drum-head-like (DHL) surface states has become a hot topic in the field of physical chemistry of materials. Via first principles, in this study, a synthesized CsCl type binary alloy, TiOs, was predicted to be a TNLS with three topological nodal lines (TNLs) centered at the X point in the kx/y/z = π plane, and these TNLs, which are protected by mirror, time reversal (T) and spatial inversion (P) symmetries, are perpendicular to one another. The exotic drum-head-like (DHL) surface states can be clearly observed inside and outside the crossing points (CPs) in the bulk system. The CPs, TNLs, and DHL surface states of TiOs are very robust under the influences of uniform strain, electron doping, and hole doping. Spin-orbit coupling (SOC)-induced gaps can be found in this TiOs system when the SOC is taken into consideration. When the SOC is involved, surface Dirac cones can be found in this system, indicating that the topological properties are still maintained. Similar to TiOs, ZrOs and HfOs alloys are TNLSs under the Perdew-Burke-Ernzerhof method. The CPs and the TNLs in both alloys disappear, however, under the Heyd-Scuseria-Ernzerhof method. It is hoped that the DHL surface property in TiOs can be detected by surface sensitive probes in the near future.

Giant Mimiviridae CsCl Purification Protocol.

While different giant viruses' purification protocols are available, they are not fully described and they use sucrose gradient that does not reach an equilibrium. Here, we report a protocol for the purification of members of the Mimiviridae family virions resulting from Acanthamoeaba castellanii infections. Viruses are harvested after cell lysis and purified through a high density CsCl gradient to optimize the isolation of the virus from the cell debris or other potential contaminants. Due to the large size of the virion capsids, reaching half a micrometer diameter, the quality of the process can be monitored by light microscopy. The resulting purified particles can then be used to perform new infections, DNA extraction, structural studies, sugar composition analyses, sub-compartment characterization or proteomic experiments.

Stable Isotope Probing of Microbiota Structure and Function in the Plant Rhizosphere.

Stable isotope probing of microbial nucleic acids applied in the rhizosphere enables (a) the identification of the active microbial community involved in root exudate assimilation and those involved in soil organic matter degradation, and (b) the study of the impact of plants via root exudates on the in situ expression of microbial functions. By incubating plants under 13CO2, fresh carbon exuded by the plant will be labeled and hence the microbial community assimilating 13C-root exudates will incorporate 13C into their cellular macromolecules. Labeled DNA, RNA, and proteins can be used to identify microorganisms that assimilated the root exudates. We provide a step-by-step protocol on how to apply stable isotope probing of DNA and RNA in the plant rhizosphere to identify the active microbial communities and analyze their gene expression.

Screening topological materials with a CsCl-type structure in crystallographic databases.

CsCl-type materials have many outstanding characteristics, i.e. simple in structure, ease of synthesis and good stability at room temperature, thus are an excellent choice for designing functional materials. Using high-throughput first-principles calculations, a large number of topological semimetals/metals (TMs) were designed from CsCl-type materials found in crystallographic databases and their crystal and electronic structures have been studied. The CsCl-type TMs in this work show rich topological character, ranging from triple nodal points, type-I nodal lines and critical-type nodal lines, to hybrid nodal lines. The TMs identified show clean topological band structures near the Fermi level, which are suitable for experimental investigations and future applications. This work provides a rich data set of TMs with a CsCl-type structure.

Affect in Peer Group Learning During Virtual Science Inquiry: Insights From Self-Reports and Video Observations.

The purpose of this study was to explore affect in small groups learning together face-to-face in a virtual learning environment. The specific aims of the study were to establish how affect within groups (valence, intensity) related to the quality of group outcome (high, average, low), and to capture individual differences within the groups by using a multimethod approach. Participants were six groups of three high school students (N = 18) who achieved distinct outcome levels. Students' self-reports of their affect and observed affect (researcher-coded selected segments from videos) were used to examine affect during three phases of interdisciplinary science inquiry, namely, planning the experiment, experimenting in the virtual laboratory, and concluding and preparing a joint group presentation. The overall results showed that positive affect was prevalent in both self-reports and researcher-coded observations across all phases. However, while self-reports displayed a strong dominance of positive affect, there was more variation in observed affect. Furthermore, the intensity of affect was higher in self-reports than in observations, for both positive and negative affect. Nonetheless, no effect of affect on group outcome was found. Finally, while within-group consistency in affect was evident in the extreme groups (high, low performance), it was more ambivalent in the groups that achieved an average performance. The results are discussed in light of the literature, and directions for future research on affect in collaborative learning are proposed.

Antibacterial properties of chitosan chloride-graphene oxide composites modified quartz sand filter media in water treatment.

In order to control bacterial pollution in water treatment, it is necessary to prepare efficient antibacterial materials. Novel chitosan chloride-graphene oxide (CSCl@GO) composites were prepared via a one-step solution blending method. The composites were characterized by FT-IR, XRD and TEM techniques. The antibacterial mechanism of CSCl@GO composites was investigated using gram-negative bacteria E. coli and gram-positive bacteria S. aureus as two model microorganisms. The antibacterial properties of CSCl@GO composites for complex bacteria in the cooling water system were researched. In addition, the CSCl@GO composites modified quartz sand filter media (CSCl@GO/QS) were synthesized. The antibacterial performance of CSCl@GO/QS filter media in secondary effluent of domestic sewage was also investigated. The results showed that E. coli and S. aureus were completely inactivated after treatment with 100 mg·L-1 of CSCl@GO composites for 15 min. When adding CSCl@GO composites to E. coli or S. aureus suspension, the protein leakage was 12.7 or 9.9 times higher than that in the blank experiment after 12 h. The antibacterial rate of CSCl@GO composites in circulating cooling water reached 95.74% when the mass fraction of GO was 0.6%. After the CSCl@GO/QS filter media were backwashed for 3 times, the antibacterial rate could still be above 90%.

Comparison of 0.1 M Stable CsCl and 1 M NH4NO3 as an Extraction Reagent to Evaluate Cs-137 Mobility in Soils.

To evaluate the mobility and bioavailability of 137Cs in soils, we compared the extraction of 137Cs with stable Cs and ammonium solutions from 137Cs-contaminated minerals and soils. The extraction yields of 137Cs with stable Cs were significantly lower than those with ammonium for minerals with frayed edge sites, but such differences were not observed for minerals without frayed edge sites. The amount of 137Cs extracted with stable Cs from soils was lower than, or equal to, that extracted with ammonium. The above results suggest that stable Cs extracted the 137Cs from easily accessible sites. Plant available 137Cs was assessed using Kochia (Bassia scoparia) cultivated in pots of contaminated soils, and compared with soil parameters including extractable 137Cs and K, and radiocesium intercept potential. The 137Cs/K ratio extracted with stable Cs solution was found to be a potential index for evaluation of the easily mobile and bioavailable fraction of 137Cs in soil.

Efficient Perovskite Solar Cells Fabricated Through CsCl-Enhanced PbI2 Precursor via Sequential Deposition.

The fabrication of high-quality perovskite film highly relies on chemical composition and the synthesis method of perovskite. So far, sequentially deposited MA0.03 FA0.97 Pb(I0.97 Br0.03 )3 polycrystalline film is adopted to produce high-performance perovskite solar cells with record power conversion efficiency (PCE). Fewer grain boundaries and incorporation of inorganic cation (e.g., cesium) would further increase device performance via sequential deposition. Here, cesium chloride (CsCl) is introduced into lead iodide (PbI2 ) precursor solution that beneficially modulates the property of PbI2 film, leading to larger grains with cesium incorporation in the resulting perovskite film. The enlarged crystal grains originate from a slower nucleation process for CsCl-containing PbI2 film when reacting with formamidine iodide, confirmed by in situ confocal photoluminescence imaging. Photovoltaic devices based on CsCl-containing PbI2 film demonstrate a higher averaging efficiency of 21.3% than 20.3% of the devices without CsCl additives for reverse scan. More importantly, the device stability is improved by CsCl additives that retain over 90% of their initial PCE value after 4000 min tracking at maximum power point under 1-sun illumination. This work paves a way to further improve the photovoltaic performance of mixed-cation-halide perovskite solar cells via a sequential deposition method.

Detection of Topoisomerase Covalent Complexes in Eukaryotic Cells.

DNA topoisomerases carry out topological transformations of DNA by introducing transient DNA breaks. The covalent intermediate of topoisomerase reactions include the topoisomerase protein covalently bound to DNA by a phosphotyrosine intermediate. Anti-cancer drugs that target topoisomerases typically trap the covalent intermediate, and generate cytotoxic enzyme dependent DNA damage. More recently, structural alterations in DNA such as DNA damage have also been shown to trap covalent intermediates of topoisomerase reactions. Understanding the action of drugs that target topoisomerases as well as determining the importance of trapped topoisomerases on genome stability requires assays that can accurately and sensitively measure levels of topoisomerase/DNA complexes. This chapter describes two approaches that have been developed to quantitate topoisomerase DNA complexes. These assays termed ICE (in vivo complex of enzymes) and RADAR (rapid approach to DNA adduct recovery) rely on isolation of genomic DNA under conditions that preserve proteins covalently bound to DNA. Covalently bound proteins are then quantitated using antibodies directed against specific topoisomerases. We describe assays in both mammalian cells and the yeast Saccharomyces cerevisiae that can measure topoisomerase/DNA covalent complexes, and give examples that can be used to enhance the quantitative reliability of these assays.