Simulation of Onset of the Capillary Surface Wave in the Ultrasonic Atomizer

The novel drug delivery system refers to the formulations and technologies for transporting a pharmaceutical compound in the body as it is needed to safely achieve its desired therapeutic effects. In this study, the onset vibrational amplitude of capillary surface waves for ultrasonic atomization spray is explained based on Faraday instability. Using ultrasonic frequency, the vibrational amplitude approached a critical point, and the liquid surface broke up into tiny drops. The micro-droplets were are steadily and continuously formed after the liquid feeding rate was optimized. The simulation study reported a minimum vibrational amplitude or onset value of 0.38 μm at 500 kHz frequency. The required minimum energy to atomize the drops was simulated by COMSOL Multiphysics simulation software. The simulation result agreed well with the numerical results of a subharmonic vibrational model that ocurred at 250 kHz frequency on the liquid surface. This newly designed single frequency ultrasonic atomizer showed its true physical characteristic of resonance on the fluid surface plane. Hence, this research will contribute to the future development of a single-frequency ultrasonic nebulizer and mechatronics for the generation of uniform atomized droplets.

Numerical Analysis of Ultrasonic Nebulizer for Onset Amplitude of Vibration with Atomization Experimental Results

In this study, the onset amplitude of the initial capillary surface wave for ultrasonic atomization of fluids has been implemented. The design and characterization of 485 kHz microfabricated silicon-based ultrasonic nozzles are presented for the concept of economic energy development. Each nozzle is composed of a silicon resonator and a piezoelectric drive section consisting of three Fourier horns. The required minimum energy to atomize liquid droplets is verified by COMSOL Multiphysics simulation software to clarify experimental data. The simulation study reports a minimum vibrational amplitude (onset) of 0.365 μm at the device bottom under the designated frequency of 485 kHz. The experimental study agrees well with the suggested frequency and the amplitude concerning the corresponding surface vibrational velocity in simulation. While operating, the deionized water was initially atomized into microdroplets at the given electrode voltage of 5.96 V. Microdroplets are steadily and continuously formed after the liquid feeding rate is optimized. This newly designed ultrasonic atomizer facilitates the development of capillary surface wave resonance at a designated frequency. A required vibrational amplitude and finite electric driving voltage promote not only the modern development in the green energy industry, but also the exploration of noninvasive, microencapsulated drug delivery and local spray needs.

Electron guiding in macroscopic borosilicate capillaries with large bending angles

This work presents experiments about the transmission of electrons with an energy of around 15 keV with beam currents up to 20 µA through macroscopic glass capillaries. A systematic study was conducted to experimentally investigate the transmission of electrons through borosilicate glass capillaries with curve angles of 90°, 180°, 270° and 360° for the first time. The focus of the work was to identify the conditions under which the injected electron current is transmitted through the capillary. It was also shown that the transmission process in the macroscopic capillaries can be optically observed by cathodoluminescence—the interaction of electrons with the capillary surface causes locally a blue glow. Different distinctive “glow states” were observed and are found to correlate with different states of electron transmission.

Spreading and Drying Dynamics of Water Drop on Hot Surface of Superwicking Ti-6Al-4V Alloy Material Fabricated by Femtosecond Laser

A superwicking Ti-6Al-4V alloy material with a hierarchical capillary surface structure was fabricated using femtosecond laser. The basic capillary surface structure is an array of micropillars/microholes. For enhancing its capillary action, the surface of the micropillars/microholes is additionally structured by regular fine microgrooves using a technique of laser-induced periodic surface structures (LIPSS), providing an extremely strong capillary action in a temperature range between 23 °C and 80 °C. Due to strong capillary action, a water drop quickly spreads in the wicking surface structure and forms a thin film over a large surface area, resulting in fast evaporation. The maximum water flow velocity after the acceleration stage is found to be 225–250 mm/s. In contrast to other metallic materials with surface capillarity produced by laser processing, the wicking performance of which quickly degrades with time, the wicking functionality of the material created here is long-lasting. Strong and long-lasting wicking properties make the created material suitable for a large variety of practical applications based on liquid-vapor phase change. Potential significant energy savings in air-conditioning and cooling data centers due to application of the material created here can contribute to mitigation of global warming.

Electron Guiding in Macroscopic Borosilicate Capillaries With Large Bending Angles

This work presents experiments about the transmission of electrons with an energy of around 15 keV with beam currents up to 20 µA through macroscopic glass capillaries. A systematic study was conducted to experimentally investigate the transmission of electrons through borosilicate glass capillaries with curve angles of 90°, 180°, 270° and 360° for the first time. The focus of the work was to identify the conditions under which the injected electron current is transmitted through the capillary. It was also shown that the transmission process in the macroscopic capillaries can be optically observed by cathodoluminescence – the interaction of electrons with the capillary surface causes locally a blue glow. Different distinctive “glow states” were observed and are found to correlate with different states of electron transmission.

Metrology of a Focusing Capillary Using Optical Ptychography

The focusing property of an ellipsoidal monocapillary has been characterized using the ptychography method with a 405 nm laser beam. The recovered wavefront gives a 12.5×10.4μm2 focus. The reconstructed phase profile of the focused beam can be used to estimate the height error of the capillary surface. The obtained height error shows a Gaussian distribution with a standard deviation of 1.3 μm. This approach can be used as a quantitative tool for evaluating the inner functional surfaces of reflective optics, complementary to conventional metrology methods.

STRUCTURAL CHANGES IN MICROCIRCULATORY VESSELS AND THEIR SURROUNDINGS IN THE PRIMARY VISUAL CORTEX OF 3- AND 18-MONTH-OLD RATS WITH RETINAL PHOTODAMAGE AND STRUCTURAL CHANGE CORRECTION

Morphofunctional changes in microvasculature play an important role in the nerve cell plasticity, the ability to change their functional state under the influence of various factors. The aim of the research was to study the morphology of the microvasculature vessels, surrounding neurons and glia cells in the primary visual cortex of 3- and 18-month-old rats in norm and under stress caused by high-intensity twenty-four-hour light exposure, as well as under correction. Materials and Methods. The experiments were carried out on 60 Wistar male rats, aged 3- and 18-months. The authors used light and electron microscopy, and morphometry to evaluate: capillary surface area and density, surface area of altered vessels (due to stasis, sludge of formed elements and thrombosis) and unchanged ones, as well as the morphology of the surrounding cells. The Kruskal-Wallis test was used for multiple comparisons within age groups, while Mann-Whitney test was used for pair comparison. Results. The authors observed different capillary reactions to light exposure in 3- and 18-month-old rats. It resulted in an increase of capillary density in 3-month-old rats and in a decrease of capillary density in 18-month-old rats (p≤0.05). Destructive changes in neurons and glia cells were more evident in 18-month-old rats. P-tyrosol administration in 3- and 18-month-old rats with light exposure led to an increase in capillary density (p≤0.05). Under correction, young rats also demonstrated an increase in the capillary surface area, and the number of glia cells and capillaries by 1 neuron (p≤0.05). Conclusion Thus, p-tyrosol improved microvascularization in the primary visual cortex under high-intensity long-term light exposure. Keywords: microcirculation, p-tyrosol, stress, primary visual cortex. Морфофункциональные изменения микроциркуляторного русла играют важную роль в пластичности нервных клеток, их способности менять свое функциональное состояние при воздействии различных факторов. Целью исследования являлось изучение морфологии сосудов микроциркуляторного русла и окружающих их нейронов и глиоцитов в первичной зрительной коре 3- и 18-месячных крыс в норме и при стрессе, вызванном высокоинтенсивным круглосуточным световым воздействием, а также в условиях коррекции. Материалы и методы. Эксперименты выполнены на 60 крысах-самцах линии «Вистар». Возраст – 3 и 18 мес. Методами световой и электронной микроскопии, морфометрии оценивали удельную площадь и численную плотность капилляров, удельную площадь измененных (со стазом, сладжем форменных элементов и тромбозом) и неизмененных сосудов, а также морфологию клеток, их окружающих. Для множественных сравнений внутри возрастных групп использовали критерий Крускала–Уоллиса, для парных – Манна–Уитни. Результаты. У 3- и 18-месячных крыс обнаружена различная реакция капилляров на световое воздействие, что выражалось в увеличении численной плотности капилляров у 3-месячных крыс и снижении – у 18-месячных (р≤0,05). Деструктивные изменения нейронов и глиоцитов более выражены у 18-месячных крыс. Коррекция п-тирозолом у 3- и 18-месячных крыс со световым воздействием приводила к увеличению численной плотности капилляров (р≤0,05). У молодых крыс при коррекции также отмечалось увеличение удельной площади капилляров, количества глиоцитов и капилляров на 1 нейрон (р≤0,05). Заключение. Применение п-тирозола улучшало состояние микроваскуляризации в первичной зрительной коре в условиях высокоинтенсивного длительного светового воздействия. Ключевые слова: микроциркуляция, п-тирозол, стресс, первичная зрительная кора.

Are transient changes in capillary surface area required to explain peritoneal transport in renal failure patients?

Background: Waniewski postulated a transient increase in peritoneal capillary surface area to fit their model predictions to experimental data of Heimburger measured in renal failure (RF) patients undergoing peritoneal dialysis (PD) but with only a 3.86% glucose dialysis fluid. The present aim is to propose a new mathematical model of the patient PD procedure that could closely fit the complete Heimburger measurement set without this postulate. Methods: The three-pore model of Rippe was used to describe transient changes in peritoneal volume and solute concentrations during a PD dwell. The predialysis, RF patient, plasma solute concentrations were assumed to remain constant during the dwell. The model was validated using the 3.86% glucose Heimburger measurements. Permeability surface area product parameters were chosen to match only the end-dwell peritoneal fluid glucose concentration and the end-dwell amounts of urea, creatinine, and Na+ removed from this simulated patient group. Then, this model was used to predict additional measurements by Heimburger on two other patient groups dialyzed with glucose concentrations of 2.27% and 1.36%, respectively. Parameters were unchanged when simulating these other patient groups. Results: To match the shape of the transient changes in drained volume and dialysis fluid glucose concentration for the 3.86% glucose group, it was necessary for only one parameter, the effective radius of glucose, to vary linearly in proportion to the dialysis fluid glucose concentration. This description was unchanged in the other two groups. Conclusion: Postulated transient increases in peritoneal capillary surface area were unnecessary to predict the entire Heimburger measurements.

Pulmonary capillary surface area in supine exercising humans: demonstration of vascular recruitment

In exercising humans, cardiac output (CO) increases, with minor increases in pulmonary artery pressure (PAP). It is unknown if the CO is accommodated via distention of already perfused capillaries or via recruitment of nonconcomitantly perfused pulmonary capillaries. Ten subjects (9 female) performed symptom-limited exercise. Six had resting mean PAP (PAPm) <20 mmHg, and four had PAPm between 21 and 24 mmHg. The first-pass pulmonary circulatory metabolism of [3H]benzoyl-Phe-Ala-Pro (BPAP) was measured at rest and at peak exercise, and functional capillary surface area (FCSA) was calculated. Data are means ± SD. Mean pulmonary arterial pressure rose from 18.8 ± 3.3 SD mmHg to 28.5 ± 4.6 SD mmHg, CO from 6.4 ± 1.6 to 13.4 ± 2.9 L/min, and pulmonary artery wedge pressure from 14 ± 3.3 to 19.5 ± 5 mmHg (all P ≤ 0.001). Percent BPAP metabolism fell from 74.7 ± 0.1% to 67.1 ± 0.1%, and FCSA/body surface area (BSA) rose from 2,939 ± 640 to 5,018 ± 1,032 mL·min−1·m−2 (all P < 0.001). In nine subjects, the FCSA/BSA-to-CO relationship suggested principally capillary recruitment and not distention. In subject 10, a marathon runner, resting CO and FCSA/BSA were high, and increases with exercise suggested distention. Exercising humans demonstrate pulmonary capillary recruitment and distention. At moderate resting CO, increasing blood flow causes principally recruitment while, based on one subject, when exercise begins at high CO, further increases appear to cause distention. Our findings clarify an important physiologic question. The technique may provide a means for further understanding exercise physiology, its limitation in pulmonary hypertension, and responses to therapy.