124 research outputs found
Mixed Langmuir-blodgett Films of Cu-3,5-bistetrabutyl Phenylporphyrin,arachidateacidand Hexatriacontane in Ordinary Environment: Auv Visible Study
Get PDF> Abstrak. Telah dilakukan studi terhadap multilapis film Langmuir-Blodgett pada kondisi eksperimen seharihari menggunakan campuran Cu-3,5-bistetra-butil fenilporpirin, asam arakidat dengan dan atau tanpa inisiator,heksatriakantone. Campuran multilapis film (perbandingan molar porpirin : asam arachidic : heksatriakantone, 1,5 : 10, r, dimana r = 0, 0,5) terdiri dari 4, 20 dan 40 lapis berhasil di transfer ke atas kaca preparat sebagai Langmuir Blodgett film dan dilakukan karakterisasi dengan spektroskopi sinar tampak (UV-visible spectroscopy). Luas daerah per molekul porpirin adalah15-21 Å2. Campuran pertama (porpirin : asam arakidat) memberikan multilapisyang baik, sedangkan campuran dengan adanya inisiator tidak menghasilkan 20 dan 40 lapisan seperti prediksi. Beberapa kemungkinan penyebab hasil tidak optimum seperti tingkat kebersihan (cleanliness), kondisi isotermaldan kecepatan kompresi saat pembentukan multilapis film akan di bahas.Kata-kata kunci: Langmuir-Blodgett Films, multilapis, Cu-3,5-bistetrabutyl-phenylporphyrinAbstract. The study of mixed Langmuir-Blodgett Films multilayer was conducted in ordinary experiment conditions by using metallo-porphyrin derivative (3,5-bistetrabutyl-phenylporphyrin with Cu as central metal) andarachidate acid with and without trigger molecule, hexatriacontane. We demonstrated that the mixed multilayer which consist of 4, 20 and 40 layers for each mixed solution (molar ratio porphyrin : arachidic acid :hexatriancontane, 1,5 : 10 : r, where r is 0, 0.5) successfully transfers into glass plates as Langmuir-Blodgett Films and characterized the transferred films using UV visible spectroscopy. The area per monolayer porphyrin moleculeis approximately 15-21 Å2. The first mixed solution (porhyrin: arachidic acid) produced good multilayer while the second mixed solution (porphyrin : arachidic acid : trigger molecule, hexatriancontane) did not produce 20 and 40layers as it was expected. Some possible problems such as cleanliness, isotherms condition and compression speed of forming multilayer will be discussed
MIXED LANGMUIR-BLODGETT FILMS OF CU-3,5-BISTETRABUTYL PHENYLPORPHYRIN,ARACHIDATEACIDAND HEXATRIACONTANE IN ORDINARY ENVIRONMENT: AUV VISIBLE STUDY
Get PDF> Abstrak. Telah dilakukan studi terhadap multilapis film Langmuir-Blodgett pada kondisi eksperimen seharihari menggunakan campuran Cu-3,5-bistetra-butil fenilporpirin, asam arakidat dengan dan atau tanpa inisiator,heksatriakantone. Campuran multilapis film (perbandingan molar porpirin : asam arachidic : heksatriakantone, 1,5 : 10, r, dimana r = 0, 0,5) terdiri dari 4, 20 dan 40 lapis berhasil di transfer ke atas kaca preparat sebagai Langmuir Blodgett film dan dilakukan karakterisasi dengan spektroskopi sinar tampak (UV-visible spectroscopy). Luas daerah per molekul porpirin adalah15-21 Ãâ¦2. Campuran pertama (porpirin : asam arakidat) memberikan multilapisyang baik, sedangkan campuran dengan adanya inisiator tidak menghasilkan 20 dan 40 lapisan seperti prediksi. Beberapa kemungkinan penyebab hasil tidak optimum seperti tingkat kebersihan (cleanliness), kondisi isotermaldan kecepatan kompresi saat pembentukan multilapis film akan di bahas.Kata-kata kunci: Langmuir-Blodgett Films, multilapis, Cu-3,5-bistetrabutyl-phenylporphyrinAbstract. The study of mixed Langmuir-Blodgett Films multilayer was conducted in ordinary experiment conditions by using metallo-porphyrin derivative (3,5-bistetrabutyl-phenylporphyrin with Cu as central metal) andarachidate acid with and without trigger molecule, hexatriacontane. We demonstrated that the mixed multilayer which consist of 4, 20 and 40 layers for each mixed solution (molar ratio porphyrin : arachidic acid :hexatriancontane, 1,5 : 10 : r, where r is 0, 0.5) successfully transfers into glass plates as Langmuir-Blodgett Films and characterized the transferred films using UV visible spectroscopy. The area per monolayer porphyrin moleculeis approximately 15-21 Ãâ¦2. The first mixed solution (porhyrin: arachidic acid) produced good multilayer while the second mixed solution (porphyrin : arachidic acid : trigger molecule, hexatriancontane) did not produce 20 and 40layers as it was expected. Some possible problems such as cleanliness, isotherms condition and compression speed of forming multilayer will be discussed.Key words:Langmuir-Blodgett Films, multilayer, Cu-3,5-bistetrabutyl phenylporphyrin</jats:p
The Explosive Sensitivity on the Complex Formation of 3-Nitro-1,2,4-Triazol-5-One and Metal Ions Based on Density Functional Study
Get PDFThe explosive sensitivity upon the formation of supramolecular interaction between the nitro group of 3-nitro-1,2,4-triazol-5-one (NTO) and metal ions (Mn+ = Li+, Na+, Be2+ and Mg2+) has been investigated using Density Functional Theory at B3LYP/6-311++G** level of theory. The bond dissociation energy (BDE) of the C1–N6 trigger bond has also been discussed for the NTO monomer and the corresponding complexes. The interaction and bond dissociation energy of the C6–N7 trigger bond follow the order of NTO-Be2+ > NTO-Mg2+ > NTO-Li+ > NTO-Na+ > NTO monomer. The enhancement of the trigger bond dissociation energy in comparison with the NTO monomer correlates well with the complex interaction energies, trigger bond length, and charge transfer. The analyses of electron density shifts have shown that the electron density of the nitro group shifts toward the C1–N6 trigger bond upon the formation of the supramolecular interaction. As result, the trigger bond is strengthened and the sensitivity of NTO is reduced. Some of the calculated results agree with the experimental values
Pengembangan LKPD Berbasis Generik Sains Menggunakan Limbah Sekitar Pada Materi Pokok Bahasan Koloid
Get PDFThis research is a research and development (R&D) that aims to find out: (1) the steps in the process of developing a generic science-based worksheet using ambient waste on colloid material (2) the level of validity and practicality of a generic science-based worksheet using ambient waste on colloid material regarding the water purification process that has been developed. The research design used 4D model (define, design, develop, and disseminate). The population in this study were all students of grade XI MIPA at SMA Negeri 1 Keruak, as many as 123 students and consisting of 4 classes. The sample used in this study was class XI MIPA-3 which consisted of 31 students. The results showed that the average validity value of the three validators for all aspects is 0.82 which indicates that the developed worksheet is in the very valid category. Meanwhile, practicality can be seen from student responses which show positive responses. The average percentage for all aspects is 85.2%, which indicates that the worksheets developed are in the very practical category. Based on these data, it can be concluded that the generic science-based worksheet using ambient waste on colloid material is valid and very practical to use in the learning process.Penelitian ini merupakan penelitian pengembangan (R&D) yang bertujuan untuk mengetahui: (1) langkah-langkah proses pengembangan LKPD berbasis generik sains menggunakan limbah sekitar pada materi pokok bahasan koloid, (2) tingkat validitas serta kepraktisan LKPD berbasis generik sains menggunakan limbah sekitar pada materi pokok bahasan koloid mengenai proses penjernihan air yang sudah dikembangkan. Rancangan penelitian menggunakan model 4D (define, design, develop, and dissemination). Populasi dalam penelitian ini adalah seluruh siswa kelas XI MIPA SMA Negeri 1 Keruak yang berjumlah 123 orang siswa kelas dan terdiri 4 kelas. Sampel yang digunakan pada penelitian ini adalah kelas XI MIPA-3 yang terdiri dari 31 siswa. Hasil penelitian menunjukkan nilai validitas dari tiga orang validator diperoleh nilai rata-rata validitas untuk seluruh aspek sebesar 0,82 yang menunjukkan bahwa LKPD yang dikembangkan masuk dalam kategori sangat valid. Sementara itu, kepraktisan dapat dilihat dari respon siswa yang menunjukkan respon positif persentase rata-rata untuk seluruh aspek sebesar 85,2% yang menunjukkan bahwa LKPD yang dikembangkan masuk dalam kategori sangat praktis. Berdasarkan data tersebut dapat disimpulkan bahwa LKPD berbasis generik sains menggunakan limbah sekitar pada materi pokok bahasan koloid yang dikembangkan bersifat valid dan sangat praktis digunakan dalam proses pembelajaran
Analisis Penguasaan Konsep Siswa yang Belajar Kimia Menggunakan Multimedia Interaktif Berbasis Green Chemistry
Get PDFPenelitian ini bertujuan untuk mengetahui pengaruh aplikasi multimedia berbasis green chemistry terhadap penguasaan konsep kimia siswa. Jenis penelitian ini adalah kuasi-eksperimen dilaksanakan dengan desain nonequivalent control group design. Penelitian ini dilakukan di salah satu satu sekolah menengah atas di Lombok Indonesia dengan melibatkan kelompok kontrol dan eksperimen. Pretest dan posttest diberikan oleh peneliti untuk menguji penguasaan konsep siswa pada materi kimia. Validitas, reliabilitas, dan tingkat kesukaran soal diuji menggunakan Rasch Model. Analisis statistik yang digunakan adalah uji prasyarat analisis data, dan uji hipotesis dengan uj t (Independent samples t-test) dengan bantuan SPSS 20 for windows. Hasil penelitian menunjukkan bahwa hasil belajar di kelas eksperimen lebih tinggi daripada di kelas kontrol. Secara statistik dapat dilihat bahwa pengujian hasil belajar menggunakan independent sample t-test menunjukkan t = 0,002 <ñ = 0,05. Kesimpulan dari penelitian ini menunjukkan bahwa multimedia interaktif berbasis green chemistry berpengaruh terhadap penguasaan konsep siswa
EXTRACTION OF STRONTIUM(II) BY CROWN ETHER: INSIGHTS FROM DENSITY FUNCTIONAL CALCULATION
No full textThe structures, energetic and thermodynamic parameters of crown ethers with different cavity size, electron donating/withdrawing substituent groups and donor atoms have been determined with density functional method at B3LYP level of theory in gas and solvent phase. Small core quasi-relativistic effective core potentials was used together with the accompanying SDD basis set for Sr2+ and DZP basis set was used for crown ether atoms. Natural bond orbital (NBO) analysis was evaluated to characterize the distribution of electrons on the complexes. The interaction energy is well correlated with the values of Strontium charge after complexation, the second order interaction energies (E2) and HOMO-LUMO energy gab (∆Egab). The interaction energy and thermodynamics parameters in gas phase are reduced in solvent phase as the solvent molecules weaken the metal-crown ether interaction. The thermodynamic parameters indicated that less feasibility to extract Sr2+ ion directly from pure water without presence of organic solvent. The theoretical values of extraction energy for Sr(NO3)2 salt from aqueous solution in different organic solvent is validated by the experimental trend. This study would have strong contribution in planning the experiments to the design of specific host ligand and screening of solvent for extraction of metal ion.</jats:p
Pengembangan Modul Praktikum Kimia Berbasis Green Chemistry Pada Materi Kesetimbangan Kimia Untuk Meningkatkan Minat Belajar Siswa Kelas XI
Get PDFThis study aims to determine the feasibility, practicality, and effectiveness of the green chemistry-based chemistry practicum module on chemical equilibrium material to increase student interest in learning. The research uses the R&D (Research and Development) 4-D model modified into three steps (3-D), namely Define, Design, Develop. This design was modified into three steps due to the limitations of the researcher to carry out the fourth stage of Disseminate. The results of the validity assessment by a validator consisting of two chemistry education lecturers based on the Aiken'V index of 0.77 (valid or feasible). The practical assessment of the chemistry practicum module by the class XI chemistry teacher was tested practically with a percentage of 92.67% (very practical) and received a good response from students in class XI MIPA 2 with an average percentage of 88.15% (very practical). The results of the effectiveness of the practicum module are taken from student interest in learning data, based on the learning interest category index, the average value is 4.22 (effective). The results of the study indicate that the green chemistry-based chemistry practicum module on the chemical equilibrium material developed is feasible, practical and effective to increase student interest in learningPenelitian ini bertujuan untuk mengetahui kelayakan, kepraktisan, dan keefektifan modul praktikum kimia berbasis green chemistry pada materi kesetimbangan kimia untuk meningkatkan minat belajar siswa. Penelitian menggunakan metode R&D (Research and Development) model 4-D dimodifikasi menjadi tiga langkah (3-D) yaitu Define, Design, Develop. Desain ini dimodifikasi menjadi tiga langkah dikarenakan keterbatasan peneliti untuk melakukan tahap ke empat Disseminate. Hasil penilaian kevalidan oleh validator yang terdiri dari dua dosen pendidikan kimia dan satu orang guru kimia berdasarkan indeks Aiken’V sebesar 0,77 (valid atau layak). Penilaian kepraktisan modul praktikum kimia oleh guru kimia kelas XI teruji praktis dengan persentase 92,67% (sangat praktis) serta mendapat respon baik dari peserta didik kelas XI MIPA 2 dengan persentase rata-rata 88,15% (sangat praktis). Hasil keefektifan modul praktikum diambil dari data minat belajar siswa, berdasarkan indeks kategori minat belajar diperoleh nilai rata-rata sebesar 4,22 (efektif). Hasil penelitian tersebut menunjukkan bahwa modul praktikum kimia berbasis green chemistry pada materi kesetimbangan kimia yang dikembangkan layak, praktis dan efektif untuk meningkatkan minat belajar siswa
Analysis Magnetic Mineral Content of Natural Iron Sand in Beach Island Lombok as Basic Materials of Micro Wave Absorbers
Get PDFThis study aims to analyze the content of the magnetic mineral compound of natural iron sand on the beach of Lombok Island. This study uses the experimental method by taking primary data which is carried out in three locations, namely at Ijobalit Beach (East Lombok), Cemara Beach (West Lombok), and Telindung Beach (East Lombok). The study stage begins with a separation of natural iron sand, then a magnetic mineral separation is carried out to obtain Fe3O4 powder. The last stage is testing the Fe content using AAS (atomic absorption spectrophotometry). The research results were obtained by the percentage of magnetic mineral content from Ijobalit beach sand, Cemara Beach, and Telindung Beach respectively 93.56, 72.99, and 87.00%. The results showed that natural iron sand from Ijobalit beach had great potential to be used as a basic material for making microwave absorbers
EXTRACTION OF STRONTIUM(II) BY CROWN ETHER: INSIGHTS FROM DENSITY FUNCTIONAL CALCULATION
Get PDFThe structures, energetic and thermodynamic parameters of crown ethers with different cavity size, electron donating/withdrawing substituent groups and donor atoms have been determined with density functional method at B3LYP level of theory in gas and solvent phase. Small core quasi-relativistic effective core potentials was used together with the accompanying SDD basis set for Sr2+ and DZP basis set was used for crown ether atoms. Natural bond orbital (NBO) analysis was evaluated to characterize the distribution of electrons on the complexes. The interaction energy is well correlated with the values of Strontium charge after complexation, the second order interaction energies (E2) and HOMO-LUMO energy gab (∆Egab). The interaction energy and thermodynamics parameters in gas phase are reduced in solvent phase as the solvent molecules weaken the metal-crown ether interaction. The thermodynamic parameters indicated that less feasibility to extract Sr2+ ion directly from pure water without presence of organic solvent. The theoretical values of extraction energy for Sr(NO3)2 salt from aqueous solution in different organic solvent is validated by the experimental trend. This study would have strong contribution in planning the experiments to the design of specific host ligand and screening of solvent for extraction of metal ion
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