On the relationship between spectroscopic constants of diatomic molecules: a machine learning approach

Through a machine learning approach, we show that the equilibrium distance, harmonic vibrational frequency and the binding energy of diatomic molecules are universally related, independently of the nature of the bond of a molecule.

Particle pairs and trains in inertial microfluidics

Staggered and linear multi-particle trains constitute characteristic structures in inertial microfluidics. Using lattice-Boltzmann simulations, we investigate their properties and stability, when flowing through microfluidic channels. We confirm the stability of cross-streamline pairs by showing how they contract or expand to their equilibrium axial distance. In contrast, same-streamline pairs quickly expand to a characteristic separation but even at long times slowly drift apart. We reproduce the distribution of particle distances with its characteristic peak as measured in experiments. Staggered multi-particle trains initialized with an axial particle spacing larger than the equilibrium distance contract non-uniformly due to collective drag reduction. Linear particle trains, similar to pairs, rapidly expand toward a value about twice the equilibrium distance of staggered trains and then very slowly drift apart non-uniformly. Again, we reproduce the statistics of particle distances and the characteristic peak observed in experiments. Finally, we thoroughly analyze the damped displacement pulse traveling as a microfluidic phonon through a staggered train and show how a defect strongly damps its propagation. Graphical abstract

Optical Resonators based on Casimir Forces -INVITED

The work here presented demonstrates theoretically that it is possible to create optical resonators based on levitation properties of thin films subjected to repulsive Casimir-Lifshitz forces. Our optical cavity design is made up of commonly found materials, such as silicon oxide, polystyrene or gold, with glycerol as a mediating medium, which supports high Q-factor optical modes at visible frequencies. The balance between flotation and repulsive Casimir-Lifshitz forces in the system allows the fine-tuning of the optical cavity thickness and hence its modes. Finally, we show that well-defined spectral features in the reflectivity allows by indirect means, an accurate prediction of the estimated equilibrium distance at which some part of the optical cavity arrangement levitates.

Anisotropy of Graphene Nanoflake Diamond Interface Frictional Properties

Using molecular dynamics (MD) simulations, the frictional properties of the interface between graphene nanoflake and single crystalline diamond substrate have been investigated. The equilibrium distance between the graphene nanoflake and the diamond substrate has been evaluated at different temperatures. This study considered the effects of temperature and relative sliding angle between graphene and diamond. The equilibrium distance between graphene and the diamond substrate was between 3.34 Å at 0 K and 3.42 Å at 600 K, and it was close to the interlayer distance of graphite which was 3.35 Å. The friction force between graphene nanoflakes and the diamond substrate exhibited periodic stick-slip motion which is similar to the friction force within a graphene–Au interface. The friction coefficient of the graphene–single crystalline diamond interface was between 0.0042 and 0.0244, depending on the sliding direction and the temperature. Generally, the friction coefficient was lowest when a graphene flake was sliding along its armchair direction and the highest when it was sliding along its zigzag direction. The friction coefficient increased by up to 20% when the temperature rose from 300 K to 600 K, hence a contribution from temperature cannot be neglected. The findings in this study validate the super-lubricity between graphene and diamond and will shed light on understanding the mechanical behavior of graphene nanodevices when using single crystalline diamond as the substrate.

Temperature Dependence of the Bulk Elasticity Modulus of Aliphatic Alcohols and Their Fluorinated Analogs

The density of some fluorinated and non-fluorinated normal monoatomic alcohols and the sound propagation velocity in them have been studied experimentally in a temperature interval of 293–363 K. The bulk modulus of elasticity is calculated, and its relation with the intermolecular interaction energy is analyzed. The energy of intermolecular interaction in fluorinated alcohols is shown to be lower than in their non-fluorinated analogs. The substitution of hydrogen atoms by fluorine ones in the molecules of aliphatic alcohols increases the equilibrium distance between the molecules.

IMPLEMENTASI TITIK KOORDINAT TENGAH KABUPATEN ATAU KOTA DALAM PERHITUNGAN JADWAL WAKTU SALAT

<p class="IABSSS">Study literature of Islamic Astronomy in case prayer times, is less from getting specific attention. Furthermore, the schedule of prayer times is very complex. Such as its still being distributed in form converting one to another area. It should be computed based on each district or city. Appearing new case that is coordinates point data (latitude and longitude) where used as center point computations. This thesis is researched the effect and importance implementation of center coordinate point from district or city in the determining of prayer times schedule. The research used mathemathic analytic descriptive and comparative analysis methods. With purpose to know in detail the comparation result from prayer times computations using center coordinate point and otherwise. The result of research shows the effect prayer times schedule can be applied for one district or city area. Meanwhile, computed prayer times schedule that use another center point coordinate not exactly can be applied in one district or city area. Though coordinate different value more than 0,5° and its position located in the south and east center coordinate point. Center coordinate point must be applied because at the base this coordinate point have been considered geographical aspect. Where in width side for the north, south, east and west have been considered and have the equilibrium distance.</p><p class="IABSSS">[]</p><p class="IABSSS">Kajian studi Astronomi Islam dalam persoalan waktu salat kurang mendapat perhatian khusus. Padahal persoalan jadwal waktu salat sangat komplek, seperti masih beredarnya jadwal waktu salat yang dikonversi dari satu daerah ke daerah lain. Sudah seharusnya jadwal waktu salat disusun berdasarkan kabupaten atau kota masing-masing. Persoalan baru yang muncul adalah data titik koordinat (lintang dan bujur) mana yang akan digunakan sebagai acuan perhitungannya. Dalam tulisan ini meneliti dampak dan perlunya implementasi titik koordinat tengah kabupaten atau kota dalam perhitungan jadwal waktu salat. Penelitian ini menggunakan metode deskriptif analitis matematis dan analisis komparatif, yang bertujuan untuk mengetahui secara detail hasil perbandingan perhitungan jadwal waktu salat dengan menggunakan titik koordinat tengah dan selain titik koordinat tengah. Penelitian ini menemukan bahwa, dampaknya jadwal waktu salat dapat diberlakukan untuk satu wilayah kabupaten atau kota. Sedangkan jadwal waktu salat yang diperhitungkan menggunakan selain titik koordinat tengah belum tentu dapat diberlakukan untuk satu wilayah kabupaten atau kota, apalagi selisih koordinatnya diatas 0,5° dan posisinya berada di sebelah selatan dan timur dari titik koordinat tengah. Titik koordinat tengah perlu diimplementasikan, karena pada dasarnya titik koordinat ini telah mempertimbangkan aspek geografis. Dimana dalam segi luas untuk bagian utara, selatan dan timur, barat nya telah dipertimbangkan dan jaraknya pun seimbang.</p>

Interplay of point multipole moments and charge penetration for intermolecular electrostatic interaction energies from the University at Buffalo pseudoatom databank model of electron density

The strength of the University at Buffalo DataBank (UBDB) inEesestimation is mainly due to charge overlap effects because the UBDB offers continuous representation of charge density which allows for a direct account of charge penetration in the derivation of electrostatic energies. In the UBDB model, these effects begin to play an important role at distances below twice the equilibrium distance and significantly increase as distances decrease. At equilibrium distances they are responsible for 30–50% ofEesfor polar molecules and around 90% ofEesfor nonpolar molecules. When the energy estimation from the UBDB is reduced to point multipoles, the results are comparable to point charges fitted to electrostatic potentials. On the other hand, particular components of energy from point multipole moments from the UBDB model are sensitive to the type of interaction and might be helpful in the characterization of interactions.