Pandemi Covid-19 menyebabkan kegiatan eksperimen kinematika gerak dilakukan secara non-laboratorium di rumah dengan menggunakan alat dan bahan yang murah dan mudah ditemui serta berbantuan aplikasi Tracker Video Analysis (TVA). Penelitian ini bertujuan untuk menganalisis efektivitas dan respon mahasiswa pada kegiatan eksperimen non-laboratorium pada materi kinematika gerak menggunakan aplikasi TVA. Percobaan dilakukan secara eksperimental dengan pendekatan kuantitatif untuk mendapatkan hubungan antarvariabel pada gerak translasi, rotasi, dan vibrasi. Selain itu juga digunakan metode survey untuk mengetahui respon mahasiswa terhadap kegiatan eksperimen ini. Hasil percobaan menunjukkan bahwa sebanyak 5 dari 6 hubungan antarvariabel maupun konstanta teoritis dapat dibuktikan melalui kegiatan eksperimen ini. Respon mahasiswa terhadap kegiatan ini adalah memuaskan dengan nilai rata-rata 8,16. Jadi dapat disimpulkan bahwa, kegiatan percobaan non-laboratorium pada materi kinematika gerak menggunakan aplikasi TVA efektif untuk membuktikan dasar teori, hubungan antarvariabel dan beberapa konstanta teoritis, serta mendapatkan respon memuaskan dari mahasiswa.

This article reports the results synthesis of crystalline (Fe3O4@c-SiO2) and amorphous (Fe3O4@a-SiO2) nanoparticles from natural resources (iron sand and silica sand). The synthesis of Fe3O4 and SiO2 nanoparticles used co-precipitation and hydrothermalcoprecipitation methods with polyethylene glycol (PEG) 4000 as a template. The XRD data analysis presented that the amorphous SiO2 particles were successfully produced using hydrothermal and co-precipitation methods. The XRD data analysis also presented that the crystalline phases were formed in quartz and tridymite phases after calcination process of the amorphous phase. SEM images exhibited that the amorphous phase had different particle size and morphology from the crystalline phase. FTIR spectra presented some absorption peaks of new functional groups indicating the existence of Si-O-Si (silanol), Fe-O, C-N, and Fe-O-Si as new functional groups.

As one of the most studied conductive polymers, polyaniline (PANi) has a variety of applications, one of which is an active gas sensor, due to the presence of amine and imine groups in PANi that can easily react with gas. Quartz crystal microbalance (QCM) is a piezoelectric sensor with the working principle of frequency changes as a result of changes in mass on its surface. As an active gas sensor material on the QCM substrate, PANi must be deposited in the form of a thin layer. A good quality of thin film is if the film does not give loading the effect on QCM and has a homogeneous morphology. This research has succeeded in depositing PANi thin films by surface polymerization method by varying the parameters of PANi solution concentration and deposition time. Deposition parameters that are varied can be seen its effect on the viscoelasticity and morphology of PANi thin film formed. The viscoelasticity of the thin film was interpreted from the measurement of the thin layer impedance using an impedance analyser, while the morphology of the thin film was characterized using SEM. From the results of this study it was found that with the surface polymerization method, the PANi thin layer impedance value changes with the deposition time which is getting longer, but the change in impedance value is not significant and does not give a loading effect on QCM. At the same deposition time with different solution concentrations, the impedance value of the formed layer also does not give a loading effect on QCM. Although it has successfully deposited PANi with a surface polymerization method, the morphology of the PANi film formed is not yet homogeneous, as seen from the formation of PANi agglomeration on the QCM surface.

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The effect of different solvents and solution concentration on viscoelastic behaviour and morphology of polyaniline (PANi) coating was investigated in this study. The PANi coating on a QCM sensor was created by spin coating with various solvents, such as NMP, m-cresol, and DMF with varying concentrations of 1-4% by weight of PANi. The viscoelastic behaviour was observed by impedance analyser and morphology of the PANi coating was observed via optical microscope and SEM/EDX. The viscoelasticity was measured to determine whether the coating produces an acoustic load (loading effect). The observations showed that the different solvents give a different effect on the impedance value of the PANi coating. With m-cresol solvent, the impedance value in the series resonant frequency was so large, indicating the PANi coating was not rigid and produce a loading effect on QCM sensor. From morphology observation showed that homogeneity of the polyaniline coating is still poor. There is an agglomeration of polyaniline powder which is insoluble in the solvent used. From the viscoelastic properties of the coating, the optimum value was obtained in PANi coating with NMP solvent.