Ketidaklaziman Kolokasi Pembelajar Bipa dan Implikasinya terhadap Pembelajaran Bahasa

Unacceptable Collocations by Learners of Indonesian as a ForeignLanguage and the Implication in Language Learning. Foreign language learners\u27ability to collocate words that are natural and acceptable in the target language isimportant in foreign language learning; however, it is notoriously difficult forforeign language learners and sometimes makes them frustrated. This studyattempts to describe the negative transfer of English collocations into Indonesiancollocations made by learners of Indonesian as a foreign language in their writingassignments. This study employed a qualitative descriptive method. The data werecollected from 36 writing assignments by 12 learners whose mother tongue isEnglish. They were trainee teachers with experience in teaching Indonesian inAustralia. The finding shows that there are 176 unnatural Indonesian collocations,some of which are negative transfers of learners\u27 mother tongue. This suggests thatdirect teaching of collocations should be given special emphasis in teachingIndonesian as a foreign language

Efficiently Stabilized Spherical Vaterite CaCO₃ Crystals by Carbon Nanotubes in Biomimetic Mineralization

Carbon nanotubes were used to induce the formation of spherical vaterite crystals and stabilize the metastable crystals in the biomimetic mineralization of CaCO3 for the first time. It was found that carboxyl-functionalized multiwalled/single-walled carbon nanotubes (MWNT-COOH/SWNT-COOH) can favor the formation of spherical vaterite crystals and stabilize the crystals. In the presence of CNT-COOH, CaCO3 vaterite crystals with diameters of ca. 1−7 μm coated and embedded with the carbon nanotubes (CNTs) were obtained in 30 min by adding Na2CO3 aqueous solution to the aqueous solution of CaCl2. The spherical vaterite crystals covered by the carboxylic CNTs can exist stably in water for a week. Carboxylic-polymer-functionalized CNTs can also facilitate the formation of spherical vaterite crystals, whereas the formed crystals completely transformed into thermodynamically stable calcite crystals in water within 10 h. “Offline” TEM observations of the mineralization process of CaCO3 in the presence of CNT-COOH or pristine CNTs revealed the stability mechanism of vaterite crystals with carboxylic CNTs. The crystals nucleate at the carboxyl groups of CNT-COOH, grow around the CNTs, and finally form spherical vaterite crystals embedded and covered by the CNTs. The strong interaction between CNT-COOH and crystals together with the strong mechanical strength of CNTs stabilizes the formed vaterite crystals and makes them difficult to dissolve in water. These findings announce that nanomaterials could strongly influence the mineralization of biomineralization matters, which may help us prepare novel biomaterials and bionanomaterials

Efficiently Stabilized Spherical Vaterite CaCO₃ Crystals by Carbon Nanotubes in Biomimetic Mineralization

Carbon nanotubes were used to induce the formation of spherical vaterite crystals and stabilize the metastable crystals in the biomimetic mineralization of CaCO3 for the first time. It was found that carboxyl-functionalized multiwalled/single-walled carbon nanotubes (MWNT-COOH/SWNT-COOH) can favor the formation of spherical vaterite crystals and stabilize the crystals. In the presence of CNT-COOH, CaCO3 vaterite crystals with diameters of ca. 1−7 μm coated and embedded with the carbon nanotubes (CNTs) were obtained in 30 min by adding Na2CO3 aqueous solution to the aqueous solution of CaCl2. The spherical vaterite crystals covered by the carboxylic CNTs can exist stably in water for a week. Carboxylic-polymer-functionalized CNTs can also facilitate the formation of spherical vaterite crystals, whereas the formed crystals completely transformed into thermodynamically stable calcite crystals in water within 10 h. “Offline” TEM observations of the mineralization process of CaCO3 in the presence of CNT-COOH or pristine CNTs revealed the stability mechanism of vaterite crystals with carboxylic CNTs. The crystals nucleate at the carboxyl groups of CNT-COOH, grow around the CNTs, and finally form spherical vaterite crystals embedded and covered by the CNTs. The strong interaction between CNT-COOH and crystals together with the strong mechanical strength of CNTs stabilizes the formed vaterite crystals and makes them difficult to dissolve in water. These findings announce that nanomaterials could strongly influence the mineralization of biomineralization matters, which may help us prepare novel biomaterials and bionanomaterials

Supraparamagnetic, Conductive, and Processable Multifunctional Graphene Nanosheets Coated with High-Density Fe₃O₄ Nanoparticles

The amazing properties of graphene are triggering extensive interests of both scientists and engineers, whereas how to fully utilize the unique attributes of graphene to construct novel graphene-based composites with tailor-made, integrated functions remains to be a challenge. Here, we report a facile approach to multifunctional iron oxide nanoparticle-attached graphene nanosheets (graphene@Fe3O4) which show the integrated properties of strong supraparamagnetism, electrical conductivity, highly chemical reactivity, good solubility, and excellent processability. The synthesis method is efficient, scalable, green, and controllable and has the feature of reduction of graphene oxide and formation of Fe3O4 nanoparticles in one step. When the feed ratios are adjusted, the average diameter of Fe3O4 nanoparticles (1.2−6.3 nm), the coverage density of Fe3O4 nanoparticles on graphene nanosheets (5.3−57.9%), and the saturated magnetization of graphene@Fe3O4 (0.5−44.1 emu/g) can be controlled readily. Because of the good solubility of the as-prepared graphene@Fe3O4, highly flexible and multifunctional films composed of polyurethane and a high content of graphene@Fe3O4 (up to 60 wt %) were fabricated by the solution-processing technique. The graphene@Fe3O4 hybrid sheets showed electrical conductivity of 0.7 S/m and can be aligned into a layered-stacking pattern in an external magnetic field. The versatile graphene@Fe3O4 nanosheets hold great promise in a wide range of fields, including magnetic resonance imaging, electromagnetic interference shielding, microwave absorbing, and so forth

Facile Synthesis of Multiamino Vinyl Poly(amino acid)s for Promising Bioapplications

We presented a general and facile strategy to prepare biocompatible multiamino polymers. Series of new monomers were synthesized by esterification of 2-hydroxyethyl methacrylate (HEMA) and Boc-amino acids, such as Boc-l-phenylalanine, Boc-glycine, Boc-l-alanine, Boc-l-valine, and Boc-l-lysine. Subsequent vinyl polymerization of monomers gave rise to vinyl poly(amino acid)s with a side primary amino group at each unit if deprotected. Both atom transfer radical polymerization (ATRP) and conventional free radical polymerization (FRP) were employed to prepare the multiamino polymers. A well controlled effect upon molecular weight with the standard first-order kinetics was achieved in cases of ATRP, and high molecular weight polymers were obtained via FRP. MTT assay showed that cell survival rates for the multiamino polymers were almost maintained above 90% and that their cytotoxicities were much lower than that of linear PEI (PEI 25000). Zeta potential measurements demonstrated that the vinyl poly(amino acid)s are electropositive, and AFM measurements showed that the vinyl poly(amino acid)s could tightly condense DNA into granular structures at a suitable concentration. The combination of facile availability, controlled productivity, low cytotoxicity and strong binding ability with DNA promises the great potential of the novel multiamino polymers in bioapplications

Heterogenous regional responses measured by the sensitive people.

<p>(a) The positive relationship between the percentage of sensitive people and the total amount of active people who has posted a tweet about a certain event at least once. (b) The nonlinear relationship between the percentage of sensitive people and the number of different <math><msubsup><mi>C</mi><mi>i</mi><mi>p</mi></msubsup></math> in all regions. The more people take part in the discussions about an event, the more heterogeneity of people will appear that cause the diversity of human responses as shown in Fig H in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0138673#pone.0138673.s001" target="_blank">S1 Appendix</a>.</p

Silyl Radical Cascade Cyclization of 2‑Isocyanothioanisole toward 2‑Silylbenzothiazoles through Radical Initiator–Inhibitor Symbiosis

A demethylative silyl radical cascade cyclization of 2-isocyanothioanisoles toward 2-silylated benzothiazole building blocks has been developed. The development of a “radical initiator–inhibitor symbiosis” system solves the challenge of otherwise dominant methyl radical-triggered side reactions brought about by kinetically unfavored generation of reactive silyl radical species. The products accessed in this protocol are amendable to various downstream functionalization reactions, including the quick construction of a topoisomerase II inhibitor via a Hiyama cross-coupling reaction and of an antiviral agent via a fluoride-/hydroxide-free nucleophilic substitution to acyl chloride

Sliding Supramolecular Polymer Brushes with Tunable Amphiphilicity: One-Step Parallel Click Synthesis and Self-Assembly

A one-step parallel grafting strategy is presented to readily prepare multifunctional complex macromolecules and miktoarm polymer brushes. Typically, a series of amphiphilic “sliding supramolecular polymer brushes” (SSPBs) were synthesized with cyclodextrin-based polyrotaxanes (PRs) as backbones. The amphiphilicity of SSPBs could be facilely tuned by the feed ratio of hydrophilic poly(ethylene glycol) (PEG) and hydrophobic palmitoyl (C16) side chains. Click chemistry of Cu(I)-catalyzed azide−alkyne cycloaddition was employed as the parallel coupling reaction, and high grafting density (ca. 18 side chains immobilized on each α-cyclodextrin ring) and click conversion (∼100%) was achieved in a short reaction time (several minutes to 3 h). The SSPB with close proportion of PEG to C16 miktoarms showed balanced amphiphilicity and could aggregate into a Janus film at the interface of hexane and water, which was confirmed with a dye-labeling method and fluorescence measurements. The amphiphilic SSPBs could also assemble into microporous films on mica surfaces via spin-coating. The formation of the superstructured films was proved to be affected by the relative humidity, rotational speed of spin-coating, and composition of SSPBs

<i>In situ</i> Polymerization Approach to Graphene-Reinforced Nylon-6 Composites

We reported an efficient method to prepare nylon-6− (PA6−) graphene (NG) composites by in situ polymerization of caprolactam in the presence of graphene oxide (GO). During the polycondensation, GO was thermally reduced to graphene simultaneously. By adjusting the feed ratio of caprolactam to GO, various composites with 0.01−10 wt % content of graphene were obtained. The highly grafting nylon-6 arms on graphene sheets was confirmed by XPS, FTIR, TGA and AFM measurements, showing the grafting content up to 78 wt % and homogeneous 2D brush-like morphology from AFM observations. The efficient polymer-chain grafting makes the graphene homogeneously dispersed in PA6 matrix and depresses the crystallization of PA6 chains. Furthermore, we prepared NG fibers by melt spinning process, and found that the tensile strength increased by 2.1 folds and Young’s modulus increased by 2.4 folds with the graphene loading of 0.1 wt % only, revealing an excellent reinforcement to composites by graphene. The in situ condensation polymerization approach paves the way to prepare graphene-based nanocomposites of condensation polymers with high performances and novel functionalities

General Approach to Individually Dispersed, Highly Soluble, and Conductive Graphene Nanosheets Functionalized by Nitrene Chemistry

A unified approach to covalently functionalize graphene nanosheets based on nitrene chemistry is reported. This strategy is simple and efficient, allowing various functional moieties (e.g., hydroxyl, carboxyl, amino, bromine, long alkyl chain, etc.) and polymers (e.g., poly(ethylene glycol), polystryene) to covalently and stably anchor on graphene to produce single-layer functionalized graphene from graphene oxide in a one-step reaction. The structure and morphology of nanosheets are characterized using microscopy (AFM, SEM, TEM), spectroscopy (FTIR, XPS, Raman), thermal gravimetric analysis (TGA), and X-ray diffraction (XRD) measurements. The resulting functionalized graphene nanosheets are electrically conductive, readily dispersible in solvents and easily processable, making them promising candidates for further modification and applications such as nanohybrids, and polymer composites, etc. The presented work provides a general methodology to prepare individually dispersed graphene nanosheets with various functionalizations and properties, paving the way for the synthesis and applications of functionalized graphene materials