Design and Synthesis of a Chiral Halogen-Bond Donor with a Sp3-Hybridized Carbon–Iodine Moiety in a Chiral Fluorobissulfonyl Scaffold

The first example of a chiral halogen-bond donor with a sp3-hybridized carbon–iodine moiety in a fluorobissulfonyl scaffold is described. The binaphthyl backbone was designed as a chiral source and the chiral halogen-bond donor (R)-1 was synthesized from (R)-1,1′-binaphthol in 11 steps. An NMR titration experiment demonstrated that (R)-1 worked as a halogen-bond donor. The Mukaiyama aldol reaction and quinoline reduction were examined using (R)-1 as a catalyst to evaluate the asymmetric induction.

A case study of direct assessment of students’ manipulative skills in chemistry practical: Perspective of lecturers

Direct assessment has adopted in matriculation college as an innovative change in assessment method for practical in line with the implementation of outcome-based education. The purpose of this study was to obtain the views of matriculation lecturers on the use of direct assessment to assess students’ manipulative skills in titration experiment during Chemistry practical. A qualitative case study approach was adopted, in which four matriculation lecturers were purposely selected. Observation and interview were conducted to obtain their views regarding to the perception, implementation, effectiveness, and critical factors for sustainability of direct assessment. The findings of the study indicated that lecturers positively perceived direct assessment were able to enhance students’ manipulative skills in Chemistry practical, by identifying their weaknesses in skills and to increases their motivation in hands-on practical. Several issues such as lack of skills among lecturers and the requiring of excessive effort needed to overcome in order to sustain the implementation of direct assessment in matriculation college.

Evaluation of mesotrione tolerance levels and [14C]mesotrione absorption and translocation in three fine fescue species

Fine fescues (Festuca spp.) are cool-season grasses used in low-maintenance turf areas. Mesotrione is a PRE and early-POST herbicide used during establishment of most cool-season turfgrasses, excluding fine fescues. Currently, efforts are being made to breed for increased tolerance to mesotrione in fine fescues to enhance weed control during establishment. This study was conducted to evaluate the association of foliar and root uptake of [14C]mesotrione with the tolerance of three lines each of Chewings fescue [Festuca rubra ssp. commutata Gaudin; syn. F. rubra ssp. fallax (Thuill.) Nyman], hard fescue [Festuca trachyphylla (Hack.) Hack.], and strong creeping red fescue (Festuca rubra L. ssp. rubra) lines. From a rate-titration experiment, the hierarchical rank of species for mesotrione tolerance from highest to lowest was: hard > Chewings > strong creeping red fescue. The hierarchical rank of species for foliar uptake from highest to lowest was: Chewings > strong creeping red > hard fescue. Translocation of foliar-absorbed 14C was not associated with differential tolerance levels of the three species. Root absorption was comparable among species, but differences between lines were detected within the species. The most susceptible lines of Chewings and strong creeping red fescue exhibited greater root uptake than lines with greater tolerance. Hard fescue translocated the least amount of root-absorbed radioactivity to shoots, while Chewings and strong creeping red fescues were comparable.

PENGEMBANGAN LABORATORIUM VIRTUAL BERBASIS MULTIMEDIA INTERAKTIF PADA PRAKTIKUM TITRASI ASAM BASA

ABSTRAKPenelitian ini bertujuan untuk mengembangkan laboratorium virtual dan untuk mengetahui kevalidan, kepraktisan dan keefektifan laboratorium virtual berbasis multimedia interaktif sebagai media pembelajaran pada praktikum titrasi asam basa. Diharapkan produk yang dikembangkan dapat meningkatkan hasil belajar peserta didik. Penelitian ini merupakan penelitian pengembangan dengan menggunakan model pengembangan berbasis produk Hannafin dan Peck yang terdiri dari tiga fase yaitu fase analisis kebutuhan, fase desain, dan fase pengembangan/implementasi. Subjek uji coba produk pengembangan ini adalah siswa kelas XI MIA3 SMA Negeri 6 Takalar dengan jumlah siswa 28 orang. Dalam penelitian ini, teknik pengumpulan data menggunakan kuesioner dengan skala Likert. Teknik analisis data yang digunakan yaitu analisis statistik deskriptif. Hasil penelitian menunjukkan bahwa untuk semua item dan aspek yang diukur, penilaian kevalidan media memperoleh kriteria valid, penilaian kepraktisan media berada pada kategori praktis dan keefektifan dengan N-gain = 0.785 dengan kategori tinggi. Dari hasil tersebut menujukkan media laboratorium virtual berbasis multimedia interaktif yang dikembangkan memiliki kategori valid, praktis dan efektif, sehingga dapat disimpulkan media laboratorium virtual berbasis multimedia interaktif yang dikembangkan layak dijadikan sebagai media pembelajaran. Kata kunci : Laboratorium Virtual, Multimedia Interaktif, Titrasi Asam-basa. ABSTRACTThis research aims to develop virtual laboratory in order to find its validity, practicality, and effectiveness of virtual laboratory interactive multimedia based in acids bases titration experiment. It is expected that the product developed can improve learning outcomes. This developing research uses a developing model based on Hannafin and Peck product. It contains three phases which are need analysis phase, design phase, and developing or implementing phase. The subjects of this developing product are 28 students of SMA Negeri 6 Takalar class XI MIA3. In collecting the data, the researcher applies questionnaire using Likert Scale. Data were analyzed by using descriptive statistics analysis. The findings of this research show valid of all aspects and items that have been measured for its validity and pratical for its media practicality and effective with the pretest-posttest show gain = 0.785 high category. It is concluded that the developing of virtual laboratory interactive multimedia based in acids bases titration experiment proves as valid, practical, and effective which can be properly applied as the learning media. Keywords: Virtual Laboratory, Interactive Multimedia, Acids Bases Tiration

Atividade Online como Dispositivo Formativo em EaD: um Exemplo do Experimento de Titulação

A experimentação é uma etapa fundamental na formação dos futuros profissionais ligados as ciências da natureza, visto que ela permite confrontar conceitos prévios com resultados experimentais. No entanto, no caso dos cursos em EaD essa vivência pode acabar sendo um pouco prejudicada e buscar soluções é fundamental. Nesse sentido, o uso das simulações de experimentos pode ser um grande aliado na no processo de ensino-aprendizagem dos temas presentes nas diversas disciplinas das grades. Dentro dessa perspectiva, nesse trabalho são apresentadas as etapas necessárias para a utilização dessas simulações como elemento de apoio aos alunos dessa modaliade de ensino e as discussões sobre a aplicação destas. Deixando claro, que mesmo um atividade virtual, a necessidade de contrução de roteiros para a realização da atividade e de perguntas norteadoras que motivem aos alunos a fazerem seu uso. Online Activity as a Training Device in EaD: an Example of Titration Experiment Abstract Experimentation is a fundamental step in the training of future professionals related to the natural sciences, since it allows confronting previous concepts with experimental results. However, in the case of the courses in EaD, this experience can end up being a bit impaired and seeking solutions is fundamental. In this sense, the use of simulations of experiments can be a great ally in the teaching-learning process of the themes present in the various disciplines of grids. In this perspective, this work presents the necessary steps for the use of these simulations as an element of support to the students of this modality of teaching and the discussions on the application of these simulations. Making it clear that even a virtual activity, the need to build scripts to carry out the activity and guiding questions that motivate students to make use of it. Keywords: Applets, Chemistry, Distance education

A ‘turn-on’ fluorescent chemosensor for the detection of Zn2+ ion based on 2-(quinolin-2-yl)quinazolin-4(3H)-one

Abstract2-(Quinolin-2-yl)quinazolin-4(3H)-one (Q) was synthesized via the Brønsted acid-promoted tandem cyclization/dehydrogenation reaction with a good yield. Compound Q is a selective ‘turn-on’ fluorescent sensor for Zn2+ ion without interference by Cd2+. The 1:1 binding model of Q to Zn2+ was confirmed by the Benesi-Hildebrand analysis, Job’s plot analysis and a ultraviolet-visible (UV-Vis) titration experiment. Furthermore, the light-on fluorescent response can be observed by the naked eye under UV-lamp irradiation (365 nm).