Lattice Boltzmann Model for The Volume-Averaged Navier-Stokes Equations

A numerical method, based on the discrete lattice Boltzmann equation, is presented for solving the volume-averaged Navier-Stokes equations. With a modified equilibrium distribution and an additional forcing term, the volume-averaged Navier-Stokes equations can be recovered from the lattice Boltzmann equation in the limit of small Mach number by the Chapman-Enskog analysis and Taylor expansion. Due to its advantages such as explicit solver and inherent parallelism, the method appears to be more competitive with traditional numerical techniques. Numerical simulations show that the proposed model can accurately reproduce both the linear and nonlinear drag effects of porosity in the fluid flow through porous media.Comment: 9 pages, 2 figure

EGTSyn: Edge-based Graph Transformer for Anti-Cancer Drug Combination Synergy Prediction

Combination therapy with multiple drugs is a potent therapy strategy for complex diseases such as cancer, due to its therapeutic efficacy and potential for reducing side effects. However, the extensive search space of drug combinations makes it challenging to screen all combinations experimentally. To address this issue, computational methods have been developed to identify prioritized drug combinations. Recently, Convolutional Neural Networks based deep learning methods have shown great potential in this community. Although the significant progress has been achieved by existing computational models, they have overlooked the important high-level semantic information and significant chemical bond features of drugs. It is worth noting that such information is rich and it can be represented by the edges of graphs in drug combination predictions. In this work, we propose a novel Edge-based Graph Transformer, named EGTSyn, for effective anti-cancer drug combination synergy prediction. In EGTSyn, a special Edge-based Graph Neural Network (EGNN) is designed to capture the global structural information of chemicals and the important information of chemical bonds, which have been neglected by most previous studies. Furthermore, we design a Graph Transformer for drugs (GTD) that combines the EGNN module with a Transformer-architecture encoder to extract high-level semantic information of drugs.Comment: 15 pages,4 figures,6 table

Near-Infrared Chiral Plasmonic Metasurface Absorbers

Chirality plays an essential role in the fields of biology, medicine and physics. However, natural materials exhibit very weak chiroptical response. In this paper, near-infrared chiral plasmonic metasurface absorbers are demonstrated to selectively absorb either the left-handed or right-handed circularly polarized light for achieving large circular dichroism (CD) across the wavelength range from 1.3 µm to 1.8 µm. It is shown that the maximum chiral absorption can reach to 0.87 and that the maximum CD in absorption is around 0.70. The current chiral metasurface design is able to achieve strong chiroptical response, which also leads to high thermal CD for the local temperature increase. The high-contrast reflective chiral images are also realized with the designed metasurface absorbers. The demonstrated chiral metasurface absorbers can be applied in many areas, such as optical filters, thermal energy harvesting, optical communication, and chiral imaging

In vitro Antioxidant Activities of Sodium Zinc and Sodium Iron Chlorophyllins from Pine Needles

U ovom je radu iz iglica bora izoliran klorofil, a zatim su saponifikacijom, purifikacijom i supstitucijom sintetizirani natrij-cinkov i natrij-željezov klorofilin, te natrij-bakrov klorofilin, koji je kasnije upotrijebljen kao kontrola. Kristalne su strukture dobivenih spojeva potvrđene atomskom apsorpcijskom spektroskopijom, UV-VIS spektroskopijom i metodom HPLC. Njihova je antioksidativna aktivnost procijenjena pomoću četiri biokemijske metode: uklanjanjem 2,2\u27-difenil-1-pikrilhidrazil (DPPH) radikala, redukcijskom snagom, inhibicijom izbjeljivanja β-karotena i uklanjanjem radikala superoksida, te je uspoređena s aktivnošću askorbinske kiseline. Natrij-cinkov klorofilin je pri manjim dozama imao bolja antioksidativna svojstva od natrij-željezovog i natrij-bakrovog klorofilina, i to u svim testovima. Vrijednosti EC50 klorofilina ispitanih metodom izbjeljivanja β-karotena bile su manje od one askorbinske kiseline (4,0 mg/mL), i to: 0,04 mg/mL za natrij-cinkov klorofilin, 0,38 mg/mL za natrij-željezov klorofilin i 0,90 mg/mL za natrij-bakrov klorofilin. Natrij-cinkov klorofilin učinkovitije je (p<0,05) uklanjao radikale superoksida od askorbinske kiseline. Rezultati mjerenja redukcijske snage također su bili izvrsni: vrijednosti su apsorbancije bile otprilike 1,0 pri koncentraciji od 0,5 mg/mL, što je otprilike pola od one askorbinske kiseline. Pri ispitivanju sposobnosti uklanjanja radikala DPPH svi su klorofilini imali slabiji učinak od askorbinske kiseline. Rezultati potvrđuju bioaktivni potencijal derivata klorofila, te njihovu moguću ulogu u zaštiti ljudskog zdravlja i prevenciji bolesti.Chlorophyll was extracted from pine needles, and then sodium zinc chlorophyllin (SZC) and sodium iron chlorophyllin (SIC) were synthesised by saponification, purification and substitution reaction, using sodium copper chlorophyllin (SCC) as a control. Their crystalline structures were verified by atomic absorbance spectroscopy, UV-VIS spectroscopy and HPLC. Moreover, their antioxidant activities were evaluated and compared with that of ascorbic acid through four biochemical assays: DPPH (2,2-diphenyl-1-picrylhydrazyl) radical scavenging activity, reducing power, inhibition of β-carotene bleaching and O2– scavenging activity. SZC had better antioxidant properties at a lower dosage than SIC and SCC in all assays. In the β-carotene bleaching assay, EC50 of SZC, SIC and SCC was 0.04, 0.38 and 0.90 mg/mL, respectively, much lower than that of ascorbic acid (4.0 mg/mL). SZC showed a better result (p<0.05) than ascorbic acid in the O2 – scavenging activity assay. The results obtained from reducing power determination were also excellent: the absorbance values were all about 1.0 at 0.5 mg/mL, about half of that of ascorbic acid. In the investigation of DPPH radical scavenging activity, all chlorophyllins had lower activities than ascorbic acid. These results demonstrated the potential bioactivities of chlorophyll derivatives and supported their possible role in human health protection and disease prevention