Light scattering by an elongated particle: spheroid versus infinite cylinder

Using the method of separation of variables and a new approach to calculations of the prolate spheroidal wave functions, we study the optical properties of very elongated (cigar-like) spheroidal particles. A comparison of extinction efficiency factors of prolate spheroids and infinitely long circular cylinders is made. For the normal and oblique incidence of radiation, the efficiency factors for spheroids converge to some limiting values with an increasing aspect ratio a/b provided particles of the same thickness are considered. These values are close to, but do not coincide with the factors for infinite cylinders. The relative difference between factors for infinite cylinders and elongated spheroids (a/b \ga 5) usually does not exceed 20 % if the following approximate relation between the angle of incidence $\alpha (in degrees)$ and the particle refractive index m=n+ki takes the place: \alpha \ga 50 |m-1| + 5 where 1.2 \la n \la 2.0 and k \la 0.1. We show that the quasistatic approximation can be well used for very elongated optically soft spheroids of large sizes.Comment: 12 pages, 7 figures, Accepted by Measurement Science and Technology (special OPC issue

Using of parallel computing for the quasi-static analysis of microstrip filters topology

An algorithm for calculation of multiconductor microstrip devices implemented on a substrate with slots in the ground plane using a quasistatic methods has been developed. Analysis of techniques for constructing a parallel algorithm for finding the inverse matrices for quasi-static calculation of microstrip filters was carried ou

Utilization of the wastes of vital activity

The recycling of wastes from the biological complex for use in life-support systems is discussed. Topics include laboratory equipment, heat treatment of waste materials, mineralization of waste products, methods for production of ammonium hydroxide and nitric acid, the extraction of sodium chloride from mineralized products, and the recovery of nutrient substances for plants from urine

Near-field scattering by dielectric spheroidal particles with sizes on the order of the illuminating wavelength

We present a theoretical study of electric field scattering by wavelength-sized spheroids. The incident, internal, and scattered fields are computed analytically by a spheroidal coordinate separation-of-variables solution, assuming axially incident monochromatic illumination. The main sources of possible numerical errors are identified and an additional point-matching procedure is implemented to provide a built-in test of the validity of the results. Numerical results were obtained for prolate and oblate particles with particular aspect ratios and sizes, and a refractive index of 1.33 relative to the surrounding medium. Special attention is paid to the characteristics of the near-field in close proximity to the spheroids. It is shown that particles with sizes close to the incident wavelength can produce high field enhancements whose spatial location and extension can be controlled by the particle geometry

Light scattering by a multilayered spheroidal particle

The light scattering problem for a confocal multilayered spheroid has been solved by the extended boundary condition method (EBCM) with a corresponding spheroidal basis. The solution preserves the advantages of the approach applied previously to homogeneous and core-mantle spheroids, i.e. the separation of the radiation fields into two parts and a special choice of scalar potentials for each of the parts. The method is known to be useful in a wide range of the particle parameters. It is particularly efficient for strongly prolate and oblate spheroids. Numerical tests are described. Illustrative calculations have shown that the extinction factors to converge to average values with a growing number of layers and how the extinction vary with a growth of particle porosity.Comment: 27 pages, 6 figures, accepted for publication in Applied Optic

Feedback as a key factor in business development

This article explores how to effectively foster a feedback culture within an organization. It outlines key principles for providing constructive, motivating, and impactful feedback, including timeliness, an unbiased approach, the use of «I–messages», a positive orientation, openness, and dialogue. Additionally, the article delves into methods of integrating feedback into the organization’s culture, such as one–on–one meetings, feedback cycles, performance evaluations, and cultivating a growth mindset. Furthermore, ethical principles such as confidentiality, objectivity, honesty, and an individualized approach are discussed. By adhering to these approaches and principles and implementing a feedback system within the organization’s culture, companies can create an atmosphere of continuous improvement, trust, and collaboration. A feedback culture rooted in these principles contributes to both the personal growth of employees and motivates them to align their actions with the organization’s goals, ultimately enhancing overall business effectiveness

Details of charge distribution in stable viral capsid

We present the results of Molecular Dynamics simulations of a viral capsid with the aim to analyse ion distribution on the capsid's surface that defines its stability. Two systems were modelled, a stable capsid with neutralising number of ions and an unstable capsid with low number of ions. For the ion distribution analysis the capsid's structure was identical and fixed in both simulations. It was then released for the stability analysis. The ion distribution demonstrated two types of the local regions on the inner surface of the capsid's wall: highly occupied with chloride ions in both systems despite a largely uniform electrostatic potential everywhere on the surface, and the regions that loose almost all chloride ions in the unstable capsid. The latter regions are located close to the cracks that are formed when the capsid is destabilised and thus could initiate the collapse of the capsid

Study of the effectiveness of various cannabinoid receptor 1 (CB1) agonists using molecular docking and molecular dynamics modeling

The binding of a series of small organic molecules, acting as agonists of the cannabinoid receptor CB1, was investigated by means of three methods of computational chemistry. Binding modes were predicted by means of molecular docking, and binding free energy was estimated via docking, molecular-mechanics Poisson-Boltzmann surface area method, and multistate Bennett acceptance ratio. No evident correlation was observed for the molecules between the experimental characteristics of affinity and three computed binding free energy estimates. The reasons for the discrepancy were discussed

Оцінка вільної енергії зв’язування двозарядних катіонів із функціональними групами амінокислот за допомогою сучасних силових полів.

Очистка води від іонів важких металів являє собою нагальну екологічну проблему. Активно досліджуваним способом для цього є зв'язування іонів металів за допомогою білків, які можливо виділити з легкодоступної рослинної сировини. Карбоксильні, тіолатні групи амінокислотних залишків здатні до комплексоутворення з катіонами металів, що призводить до видалення забруднювачів із води. Для досліджень активно використовуються методи обчислювальної хімії, зокрема класичне молекулярно-динамічне моделювання. У роботі проведена оцінка правильності відтворення вільних енергій зв’язування ряду двозарядних катіонів металів із функціональними групами амінокислот. Використаний сучасний набір потенціальних моделей катіонів, який коректно відтворює характеристики катіонів у водному розчині. Порівняння проведено з експериментально виміряними константами стійкості модельованих комплексів або їх структурних аналогів. Обчислення вільних енергій виконано методом алхімічного перетворення. Показано, що незважаючи на валідованість вжитих потенціальних моделей, вільні енергії зв’язування з функціональними групами амінокислот загалом відтворюються погано: помірно недооцінені для тіолатної групи та аміногрупи, надзвичайно переоцінені для карбоксилатної групи, некоректні для імідазолу. Таким чином, показано, що метод класичного молекулярно-динамічного моделювання слід з обережністю використовувати для розрахунку енергетичних характеристик зв'язування металів амінокислотами і білками