Evaluation of the Electronic Structure Resulting from ab-initio Calculations on Simple Molecules Using the Molecular Orbital Theory

Hartree Fock (HF) and Density Functional Theory (DFT) have been commonly used to model chemical problems. This study uses the Molecular Orbital Theory (MOT) to evaluate the electronic structure of five diatomic molecules generated by HF and DFT calculations. The evaluation provides an explanation of how the orbitals of a molecule come to be and how this affects the calculation of the physical quantities of the molecule. The evaluation is obtained after comparing the orbital wave functions calculated by MOT, HF, and DFT. This study found that the nature of the Highest Occupied Molecular Orbital (HOMO) of a molecule is determined by the valence orbital properties of the constituent atoms. This HOMO property greatly influences the precision of calculating the molecular electric dipole moment. This shows the importance of understanding the orbital properties of a molecule formed from the HF and DFT calculation

Komposit Kolagen Fibril-Alginat sebagai Kandidat Membran Hidrogel Skin Substitute

Telah dilakukan sintesis membran hidrogel komposit berbahan kolagen, alginat sebagai kandidat skin substitute. Tujuan dari penelitian ini adalah untuk mengetahui sifat fisikokimia dari membran hidrogel komposit kolagen-alginat. Metode yang dilakukan yaitu dengan teknik kering udarakan yang dicetak pada mika tipis selama tujuh hari pada suhu ruang. Hasil sintesis dikarakterisasi dengan PSA untuk mengetahui distribus ukuran nanopartikel perak, FTIR, penentuan morfologi dengan SEM, uji absorbsi dengan larutan PBS (Phospate Buffer Saline) uji kuat tarik, uji elongasi, uji sitotoksisitas dan uji antibakteri. Hasil analisis FT-IR pada membran memperlihatkan serapan kolagen dan alginat yang ditunjukkan dengan munculnya pergeseran pita serapan pada membrane komposit yaitu adanya Amida I dari kolagen, gugus karbonil (C=O) dari alginat. Hasil pengujian SEM membran komposit tanpa nanopartikel perak menunjukkan penebalan dinding dan pori yang lebar, sedangkan membran dengan penambahan nanopartikel perak ukuran pori lebih kecil. Berdasarkan hasil pengujian absorbsi menunjukkan semakin banyak komposisi kolagen pada membran maka semakin menurun lama membran hidrogel komposit menyerap larutan. Hasil pengujian kuat tarik menunjukkan nahwa semakin banyak komposisi kolagen pada membran hidrogel komposit maka semakin tinggi nilai kuat tariknya. Hasil uji elongasi menunjukkan semakin banyak komposisi kolagen maka semakin menurun nilai elongasinya

Study of bundled fiber based displacement sensors using theoretical model and fitting function approaches

The performance of optical fiber displacement sensors with a pair of probe is theoretically and experimentally demonstrated using a developed theoretical model and fitting function approaches. The displacement measurement is carry out by using the modulated 633nm light source in conjunction with lock-in amplifier to reduce the dc drift and interference of ambient stray light. Based on this measurement, a fitting curve is obtained, which is then compared with the theoretical results. The sensor has two slopes with a linearity of more than 99% for both theoretical and fitting approaches. With the fitting approach, linearity ranges of 500μm and 1450μm are obtained for the front and back slopes respectively. On the other hand, linearity ranges are obtained at 600μm and 1550μm for front and back slopes, respectively using the theoretical approach. The sensitivity (in arb. Units × 103) for the theoretical and fitting approaches are obtained at 1.70 and 1.92, respectively for the front slope and 0.36 and 0.40 respectively for the back slope

Design and Operation of a Concentric-Fiber Displacement Sensor

A concentric-fiber displacement sensor is demonstrated using a developed theory to support the experimental findings. The theoretical analysis uses an electromagnetic Gaussian beam approach to determine the transfer function of the sensor. The sensor has two operating ranges with a good linearity; namely, the front slope and back slope. On the front slope, the sensitivities are obtained at 3.6 and 2.1 mW/m for the theoretical and experimental approaches, respectively; while on the back slope the sensitivities are 1.6 and 0.52 mW/m for theoretical and experimental approaches, respectively. This sensor has many potential applications such as automated monitoring control, position control, and micro-displacement sensing in the hazardous regions

The antifungal agent of silver nanoparticles activated by diode laser as light source to reduce C. albicans biofilms: an in vitro study

Candida albicans is a normal flora caused fungal infections and has the ability to form biofilms. The aim of this study was to improve the antifungal effect of silver nanoparticles (AgNPs) and the light source for reducing the biofilm survival of C. albicans. AgNPs were prepared by silver nitrate (AgNO3) and trisodium citrate (Na3C6H5O7). To determine the antifungal effect of treatments on C. albicans biofilm, samples were distributed into four groups; L + P+ was treatment with laser irradiation and AgNPs; L + P- was treatment with laser irradiation only; L - P+ was treatment with AgNPs only (control positive); L - P- was no treatment with laser irradiation or AgNPs (control negative). The growth of fungi had been monitored by measuring the optical density at 405 nm with ELISA reader. The particle size of AgNPs was measured by using (particle size analyzer) and the zeta potential of AgNPs was measured by using Malvern zetasizer. The PSA test showed that the particle size of AgNPs was distributed between 7.531-5559.644 nm. The zeta potentials were found lower than - 30 mV with pH of 7, 9 or 11. The reduction percentage was analyzed by ANOVA test. The highest reduction difference was given at a lower level irradiation because irradiation with a density energy of 6.13 ± 0.002 J/cm2 resulted in the biofilm reduction of 7.07 ± 0.23% for the sample without AgNPs compared to the sample with AgNPs that increased the biofilm reduction of 64.48 ± 0.07%. The irradiation with a 450-nm light source had a significant fungicidal effect on C. albicans biofilm. The combination of light source and AgNPs provides an increase of biofilm reduction compared to the light source itself