Implementasi Pembelajaran Aktif-Kooperatif Pada Topik Fotokimia Untuk Meningkatkan Keterampilan Generik Sains Calon Guru Kimia

Penelitian ini menggunakan metode penelitian pengembangan untuk menghasilkan pembelajaran yang dapat meningkatkan keterampilan generik sains (KGS) calon guru kimia. Pembelajaran yang dikembangkan menggabungkan pembelajaran aktif dan pembelajaran kooperatif. Pembelajaran diimplementasikan pada topik Fotokimia yang diikuti oleh 70 mahasiswa. Pelaksanaan pembelajaran menyimpulkan bahwa ada perbedaan N-gain yang signifikan dalam penguasaan konsep Fotokimia dan KGS karena perbedaan tahun akademik, nilai Kimia Fisika I, dan IPK. Pembelajaran Aktif-kooperatif yang dikembangkan dapat digunakan untuk berbagai latar belakang siswa

Efektivitas Pembelajaran Stereokimia Berbasis Visualisasi 3d Molekul untuk Meningkatkan Kemampuan Spasial

Penelitian ini bertujuan menyelidiki keefektifan program pembelajaran stereokimia berbasis visualisasi 3D molekul menggunakan salah satu chemical drawing software berbasis open source yakni Avogadro, dan animasi kekiralan melalui komputer untuk meningkatkan kemampuan spasial mahasiswa calon guru. Studi menggunakan quasi experimental control group pretest-posttest design. Instrumen penelitian terdiri dari 25 soal pilihan ganda disertai alasan, disusun berdasarkan indikator tiga dimensi utama kemampuan spasial. Penelitian dilaksanakan di satu LPTK di Provinsi Lampung, semester ganjil Th. Akademik 2014/2015. Subjek penelitian terdiri dari kelas kontrol dan kelas eksperimen, masing-masing ada sebanyak 30 mahasiswa. Hasil penelitian menunjukkan bahwa rata-rata skor post test kemampuan spasial kelompok mahasiswa dengan pembelajaran stereokimia berbasis visualisasi 3D molekul secara signifikan lebih tinggi dibandingkan kelompok mahasiswa yang media pembelajarannya menggunakan molymod. Keefektifan program ditunjukkan oleh peningkatan N-gain dalam kategori sedang dan efek size (d) dalam kategori tinggi untuk ketiga dimensi utama kemampuan spasial

Perbandingan Metode Kolaborasi dengan Contoh Tugas dan Belajar Individual dalam Pengembangan Kemampuan Pemecahan Masalah Kimia

: This study was based on the individual and social constuctivist learning theory. This study was aimed to examine the effectiveness of the collaborative learning and traditional individual learning to improve the students\u27 problem solving skills. This study used the quasi-experimental design. The subjects were 60 Chemistry students enrolling the Chemistry Mathematics course. The findings showed that the effectiveness of both methods was influenced by the type of the chemistry materials being studied and relevant mathematical concepts. The problem solving skills of the students learning individually was better than those of the students learning collaboratively in the kinetics concept using the calculus concept. However, both learning settings gave the same influence on the chemistry problem solving skills using the basic mathematics concepts such as logarithma and algebra. In addition to the learning approach, the students\u27 problem solving skills were also influenced by several factors including: cognitive and learning experience factors, These findings can give contribution to the choice of learning strategies by taking into account of the influential factors

High-Pressure Crystal Structure Prediction Using Evolutionary Algorithm Simulation

We implemented a high-pressure crystal structure prediction using evolutionary algo-rithm method, one of successful method to deal with this kind of problems. This method employs three evolution operators to generate a new o spring from its parents; heredity operator, permu-tation operator, and mutation operator. We run two simulation tests to this method and found results having a good agreement with experimental results. We also found some metastable struc-tures produced by this method

Charge Transport and Recombination in TiO2 Brookite-Based Photoelectrodes

International audienceThe photoactivity of the stable nanosized TiO2 polymorphs is challenging for many advanced applications. In the present work, brookite TiO2 nanoparticles with two different shapes have been used as building blocks for the preparation of pure brookite mesoporous layers. The layers have been characterized before and after sensitization. They have been used as photoanodes in dye-sensitized solar cells (DSSCs). The cell functioning coupled processes have been investigated by the impedance spectroscopy (IS) technique at various applied voltages and compared to a reference anatase TiO2 solar cell. The investigations of the chemical capacitance and of the charge transfer resistance, R-ct, show that, compared to anatase, the brookite surface is less active for the recombination side reaction. The larger R-ct is shown to explain the higher open circuit voltage of the brookite cells. However, the charge transport is much slower in the brookite phase due to a lower electrical conductivity. This parameter has been quantified more than 1 order of magnitude lower in the brookite layers compared to the anatase one. On the whole, the efficiency of brookite DSSCs is mainly limited by two parameters, the dye loading and the charge collection efficiency

Effects of Graphene in Graphene/TiO₂ Composite Films Applied to Solar Cell Photoelectrode

A simple and effective method has been developed to prepare a composite porous film that incorporates graphene sheets and anatase TiO₂ nanoparticles. After sensitization, the films have been investigated as dye-sensitized solar cell photoelectrodes. The cell performances showed that the incorporation of an optimized graphene content of 1.2 wt % increases the power conversion efficiency by 12% due to the enhancement of the short-circuit current density (<i>J</i>_sc). The photoelectrodes have been characterized by various techniques, and the cell functioning has been studied by impedance spectroscopy over a large applied potential range. The electronic structure, charge carrier lifetime (τ_n), transport/collection time (τ_tr), and electron transport parameters of the layers have been determined. We conclude that photoelectrodes with and without graphene show no limitation due to the transport of the I^–/I₃^– redox shuttle. The rate of the charge transfer (recombination) parasitic reaction is unchanged with the presence of graphene. The electron transport in the photoelectrode is significantly faster for the composite film due to a quantified 60% increase in the layer conductivity. However, we have also shown that the charge-carrier collection efficiency is very high even without graphene, and that this parameter is not key to explain the cell-performance enhancement. Graphene also increases the film specific internal surface area. The composite films have a higher dye loading. They exhibit a better solar light absorption and a <i>J</i>_sc enlargement

Pembekalan Kemampuan Generik Bagi Calon Guru Melalui Perkuliahan Kimia Anorganik Berbasis Multimedia

Studi pembekalan kemampuan generik bagi calon guru melalui perkuliahan Kimia Anorganik berbasis multimedia bertujuan mengembangkan sebuah model perkuliahan Kimia Anorganik untuk membekali calon guru guna menumbuhkan kemampuan generik kimia. Permasalah utama penelitian ini adalah bagaimana membekali mahasiswa calon guru dengan kemampuan generik Kimia Anorganik. Model perkuliahan tersebut diimplementasikan pada mata kuliah Kimia Anorganik II di suatu universitas negeri di Bandung dengan metode Research and Development (R&D). Dari data yang dianalisis dengan SPSS for window 11.5, ternyata model perkuliahan berbasis multimedia lebih baik dari model perkuliahan reguler dalam mengembangkan kemampuan generik perkuliahan khususnya aspek pemodelan, abstraksi, dan konsistensi logis. Hasil penelitian juga menunjukkan bahwa model pembelajaran mampu meningkatkan penguasaan konsep kimia koordinasi mahasiswa khususnya konsep ligan, stereokimia dan sifat logam transisi. Uji statistik GLM (General Linear Multivariate) menunjukkan bahwa capaian ternormalisasi kemampuan generik perkuliahan antara kelas eksperimen dan kelas kontrol terdapat perbedaan yang sangat signifikan pada berbagai kategori IP Kumulatif. Model pembelajaran berbasis multimedia komputer ini mendapat respon positif mahasiswa karena dapat memanipulasi lingkungan pembelajaran mahasiswa, sehingga menyenangkan dan membangkitkan motivasi belajarnya. Sumber belajar berbasis Moodle (Modular Oriented Object Dynamic Learning Environtment) ini merupakan program aplikasi efektif yang mampu membantu mahasiswa menjelaskan materi yang dipelajari di kelas, melakukan iterasi dan membangun kemandirian belajar melalui aspek visualisasi dinamis. Dengan dikembangkannya pembelajaran Kimia Anorganik pada situs pendidikan kimia berbasis web melalui http://kimia.upi.edu/moodle/ mahasiswa lebih dapat mengembangkan materi yang sudah diterima di perkuliahan kelas secara on-line dengan lebih nyaman dan kreatif