A Procedure for Optimizing Cavitating Propeller Blades in a Given Wake

Impairment of nasal airway under intermittent hypoxia during growth period in rats

Key WordsZZMastoid•

IntroductionPeristalsis is a collective process of intestinal muscle contractions for the passage of food through the gastrointestinal tract. Although, peristalsis has been extensively studied using spatiotemporal mapping and pressure transducers both in vivo and in vitro, the quantitative analysis of peristaltic propulsion is not fully understood. Lack of a definitive tool therefore, limited drug discovery in the field of constipation including IBSC. In this study, we used directional lighting, advanced field‐imaging techniques together with intraluminal pressure recordings to determine intestinal diameter, frequency of longitudinal muscle activity and pressure changes as well as velocity of anterograde and retrograde contractions and volume output measurements to help determine the net peristaltic activity.MethodsThe basal activity of intestinal peristalsis in terms of intraluminal pressure (ILP) changes, real‐time changes in longitudinal muscle activity and intestinal lumen diameter were measured in approximately 5 cm long segments from jejunum of mouse small intestine (male, NIH Swiss) in physiological Ringer solution. Intraluminal pressure was recorded using pressure transducers connected to the oral and aboral end of each segment mounted in Perfusion Bath for Tubular Organs, (Harvard apparatus, USA). Longitudinal muscle activity was studied using CVX400 series vision system, and LumiTrax™multi‐spectrum light (Keyence, USA) using multiple tracking points in each intestinal segment. The number, strength, and amplitude of oscillations in terms of intraluminal pressure changes and longitudinal muscle activity was analyzed using custom written programs. Luminal volume output was measured using a photo‐electric drop counter unit.ResultsThe number, amplitude, duration, and frequency of high and low amplitude changes in ILP and longitudinal muscle activity was determined using a lab‐written program. The frequency of longitudinal muscle activity correlated well with the frequency of low and high amplitude pressure changes. Frequency of both these oscillations were found to be 0.7 Hz. A reduction in the ILP was found to induce high amplitude contractions which subsided as the ILP increased. Changes in intestinal diameter with time correlated to ILP changes. A reduction in luminal diameter caused an increase in ILP and when not fully compensated caused increased fluid output. The mean velocity of the contractions over time in the regions tracked was determined to be 2.5 – 2.7mm/sec with peak anterograde contraction velocity of ‐4.06 mm/sec and retrograde contractions of 12 mm/sec. This mean velocity in presence of physiological Ringer solution was thought to determine the direction of contractions along the length of the GI tract under normal conditions.InferenceFrequency of longitudinal muscle activity and ILP oscillation showed similar frequency suggesting common pacemaker activity. The velocity of the contraction and volume output over time will help determine the overall peristaltic movement and could be used as a helpful index to gauge constipation.

The characteristic depth dose deposition of ion beams, with a maximum at the end of their range (Bragg peak) allows for local treatment delivery, resulting in better sparing of the adjacent healthy tissues compared to other forms of external beam radiotherapy treatments. However, the optimal clinical exploitation of the favorable ion beam ballistic is hampered by uncertainties in the in vivo Bragg peak position. Ionoacoustics is based on the detection of thermoacoustic pressure waves induced by a properly pulsed ion beam (e.g., produced by modern compact accelerators) to image the irradiated volume. Co-registration between ionoacoustics and ultrasound imaging offers a promising opportunity to monitor the ion beam and patient anatomy during the treatment. Nevertheless, the detection of the ionoacoustic waves is challenging due to very low pressure amplitudes and frequencies (mPa/kHz) observed in clinical applications. We investigate contrast agents to enhance the acoustic emission. Ultrasound microbubbles are used to increase the ionoacoustic frequency around the microbubble resonance frequency. Moreover, India ink is investigated as a possible mean to enhance the signal amplitude by taking advantage of additional optical photon absorption along the ion beam and subsequent photoacoustic effect. We report amplitude increase of up to 200% of the ionoacoustic signal emission in the MHz frequency range by combining microbubbles and India ink contrast agents.

The use of modulated pressure in ceramic injection moulding

Focused shock waves: Concrement disintegration and stimulation of Pseudarthroses gaps request the shock wave energy at limited spatial areas. High pressure amplitudes and energies need to exceed certain thresholds of stone material for mechanical disintegration work. Accordingly the generation of fractures within the medullar bone explained the stimulation of healing proportional to the acoustic energy. Recent clinical findings reveal identical or even better outcomes at low number of shocks. Biological model: Accepting the biological model as promoted by W. Schaden, the peak pressure and the energy density of the shock waves might be lowered dramatically. Activation of the body’s healing mechanisms will be seen by ingrowth of new blood vessels and the release of growth factors. Unfocused shock wave sources: The biological model motivated the design of sources with low pressure amplitudes and energy densities. First: spherical waves generated between two tips of an electrode; and second: nearly even waves generated by generalized parabolic reflectors. Third: divergent shock front characteristics are generated by an ellipsoid behind F2. Unfocused sources are preferably designed for extended two dimensional areas/volumes like skin. Detailed acoustical parameters might be presented.

The aim of this study was to investigate whether subcutaneous melanoma impairs intrinsic cardiac function and hypoxia tolerance in mice. In addition, it was investigated whether these changes could be prevented by voluntary wheel-running exercise. The roles of different molecular pathways were also analyzed. Male mice (C57Bl/6NCrl) were divided into unexercised tumor-free group, unexercised melanoma group, and exercised melanoma group. The experiment lasted 2.7 ± 0.1 wk (determined by the tumor size) after which the heart function was measured in different oxygen levels ex vivo using Langendorff method. All the melanoma mice had lower pressure amplitude (50.3%), rate of pressure production (54.1%), and decline (52.5%) in hearts ex vivo when compared with tumor-free group. There were no functional differences between the two melanoma groups. All the groups had similar weight changes, heart weights, cardiomyocyte sizes, levels of Ca2+ channels, energy metabolism enzyme activities, lipid peroxidation, and reactive oxygen species in their cardiac tissue homogenates. However, all the melanoma mice had 7.4% lower superoxidase dismutase activity compared with the control animals, which might reduce the ability of the heart to react to changes in oxidative stress. The exercising melanoma group had a 28.6% higher average heart capillary density compared with the unexercised melanoma group. Short-term wheel running did not affect the tumor growth. In conclusion, subcutaneous melanoma seems to impair intrinsic heart function even before cachexia, and these functional alterations were not caused by any of the measured molecular markers. Short-term voluntary wheel-running exercise was insufficient to alleviate the intrinsic cardiac impairments caused by melanoma.NEW & NOTEWORTHY Melanoma has been shown to induce cardiac atrophy and impair cardiac function in vivo, however, it has not been investigated how melanoma affects the intrinsic heart function. Here, we showed that subcutaneous melanoma can impair intrinsic heart function in noncachectic mice, decreasing the heart's pressure production and relaxation. In addition, we investigated whether short-term voluntary wheel-running exercise could attenuate the impairment of intrinsic cardiac function. However, our results do not seem to support this hypothesis.

The fed human stomach displays regular peristaltic contraction waves that originate in the proximal antrum and propagate to the pylorus. High-resolution concurrent manometry and magnetic resonance imaging (MRI) studies of the stomach suggest a primary function of antral contraction wave (ACW) activity unrelated to gastric emptying. Detailed evaluation is difficult, however, in vivo. Here we analyse the role of ACW activity on intragastric fluid motions, pressure, and mixing with computer simulation. A two-dimensional computer model of the stomach was developed with the 'lattice-Boltzmann' numerical method from the laws of physics, and stomach geometry modelled from MRI. Time changes in gastric volume were specified to match global physiological rates of nutrient liquid emptying. The simulations predicted two basic fluid motions: retrograde 'jets' through ACWs, and circulatory flow between ACWs, both of which contribute to mixing. A well-defined 'zone of mixing', confined to the antrum, was created by the ACWs, with mixing motions enhanced by multiple and narrower ACWs. The simulations also predicted contraction-induced peristaltic pressure waves in the distal antrum consistent with manometric measurements, but with a much lower pressure amplitude than manometric data, indicating that manometric pressure amplitudes reflect direct contact of the catheter with the gastric wall. We conclude that the ACWs are central to gastric mixing, and may also play an indirect role in gastric emptying through local alterations in common cavity pressure.

INTRODUÇÃO: A hipertrofia adenoideana é vista com freqüência na prática otorrinolaringológica e é importante avaliar a patência nasal antes do início do tratamento. Neste trabalho, os autores buscam avaliar as mudanças na geometria nasal e nasofaringe antes e após adenoidectomia através de um método objetivo de mensuração da patência nasal, a rinometria acústica. FORMA DE ESTUDO: Clínico prospectivo. OBJETIVO: Os autores avaliam a área de secção transversal mínima (ASTM) e o volume das cavidades nasais e nasofaringe através da rinometria acústica (RA) antes e após a cirurgia de adenoidectomia. MATERIAL E MÉTODO: Vinte e três crianças que tinham indicação cirúrgica para adenoidectomia com ou sem tonsilectomia foram submetidas ao exame de RA antes e 15 dias após a cirurgia. RESULTADOS: A ASTM das fossas nasais variou, antes do uso de vasoconstritor (VC), de 0,73 cm² antes da cirurgia para 0,79 cm² após a cirurgia; após o uso de VC variou de 0,87 cm² para 0,93 cm². O volume das fossas nasais variou, antes do uso de VC, de 6,18 cm³ antes da cirurgia para 6,47 cm³ após a cirurgia; após o uso de VC variou de 8,31 cm³ para 8,65 cm³. Na nasofaringe a ASTM variou, antes do uso de VC, de 2,43 cm² antes da cirurgia para 2,69 cm² após a cirurgia; após o uso de VC variou de 2,76 cm² para 3,79 cm². Na nasofaringe o volume variou, antes do uso de VC, de 5,57 cm³ antes da cirurgia para 6,14 cm³ após a cirurgia; após o uso de VC variou de 6,51 cm³ para 8,78 cm³. CCINCLUSÃO: O aumento de ASTM e volume da nasofaringe, indicando melhora da permeabilidade nasal, concorda com a melhora dos sintomas obstrutivos referidos pelo paciente e familiares após a cirurgia de adenoidectomia.

Objective:To study whether and how bariatric surgery changes the structure of the pharyngeal cavity in obese patients with obstructive sleep apnea（OSA）. Methods:Forty-two patients who underwent laparoscopic sleeve gastrectomy were recruited. Morphological indicators（BMI, neck and waist circumference）, PSG and acoustic pharyngometry indicators were evaluated pre-operatively and 3, 6, and 12 months post-operatively. Results:All indicators including morphology, pharyngeal cavity structure and OSA severity changed significantly after surgery. Among them, BMI, neck circumference, waist circumference and AHI value were significantly reduced（P<0.001）, while pharyngeal cavity volume, pharynx volume, oropharyngeal junction area, glottis area and LSaO2 increased significantly（P<0.001）. The results of multiple comparisons showed that BMI, neck and waist circumference decreased significantly in the first 6 months, and no further decline occurred during 6 to 12 months postoperatively. The decrease in AHI and LSaO2 mainly occurred within the first 3 months postoperatively, while there was no statistically significant difference in these two indicatiors between 3 months vs. 6 months, 6 months vs. 12 months postoperatively. The area of the oropharyngeal junction increased significantly within 0 to 3 months after surgery, while the volume of the pharyngeal cavity and the area of the glottis increased at 6 months and 12 months after surgery. Conclusion:Bariatric surgery can significantly reduce body weight and reduce fat accumulation in the neck. It can also enlarge the volume and cross-sectional area of the pharyngeal cavity, and improve upper airway obstruction, therefore reduce the symptoms of sleep apnea in obese patients with OSA to a certain extent.

A detailed computational study was carried out to explore how the presence of a cavity and cavity angles influence the performance and combustion mechanisms within a scramjet combustor. This research utilized ANSYS Fluent 2021 to create hexahedral meshes and simulate the complex fluid dynamics in scramjet engines equipped with dual strut injectors. The simulations addressed various critical aspects of fluid mechanics, including the continuity, momentum (via the Navier-Stokes equations), and energy equations. These equations were used to model non-reacting flows, while the species transport equations were applied to analyse reacting flows. The turbulence within the combustor was modelled using the standard K-ε model, a common choice for such high-speed aerodynamic evaluations. The study's primary goal was to assess the effects of different geometrical configurations of cavity flame holders on the performance characteristics of an H2-based scramjet combustor overall efficiency, focusing on mixing efficiency, combustion performance, and total pressure loss. Both configurations with and without a cavity were examined. Key findings indicate that incorporating a cavity into the combustor design leads to developing a robust recirculation zone within the cavity area. This recirculation zone is pivotal in enhancing fuel-air mixing and combustion efficiency, with cavity-based combustors showing an earlier onset of combustion and achieving peak combustion efficiencies around 90–95%. The extent of the recirculation region is notably influenced by the proximity of the strut injector to the cavity's length. Additionally, the presence of a shear layer within the cavity generates a weak shock at the cavity's trailing edge. This shock interaction can adversely affect scramjet combustor performance, especially at higher cavity angles (α) and specific geometric configurations, such as an L/D ratio of 4 and α=30°. The L/D ratio of 4 and α=30° combustor model results in a 13.8% increase in turbulence intensity, which raises air-fuel mixing and there by improves mixing and combustion efficiency by 14.23% and 13.34%, compared to the other depth of the cavities. This advantage is critical, especially considering the compact length of the combustor, which is a desirable attribute in scramjet design.

The purpose of this study is to investigate the relationship between the growth and contraction processes of each blade cavity and cavitation instability, and to conduct multi-point pressure measurement tests. The experiments will be conducted using cavitation water flow tunnels installed at the Kakuda Space Center of the Japan Aerospace Exploration Agency (JAXA). In the multi-point pressure measurement experiment, a number of pressure sensors are installed in the inducer casing, and the cavity area can be estimated and the cavity length can be obtained by creating a pressure distribution between the blades during the depressurization experiments. This method makes it possible to continuously determine cavity length variation during inducer experiments and to investigate the cavity growth process. In addition, cavity length variation can be obtained with higher time resolution than in visualization experiment, allowing more detailed investigation of the unsteady cavity behaviour during cavitation instability. And two types of superposition cavitation instability were found in this study: one is Super-S R.C. and C.S., the other is Sync R.C. and C.S..

The problem of the generation of cavitation self-oscillations in a liquid flow in a pipe with two resistances is considered. The first resistance is a cavitator, behind which there is an artificial ventilated cavity, where the mean pressure is greater than the atmospheric pressure, while the liquid and gas outflow into the atmosphere takes place through the second resistance. Investigations show that the self-oscillation frequencies are chiefly determined by the cavity properties and the conditions of the outflow into the atmosphere. The generation of different self-oscillation modes is directly associated with the number of waves formed along the cavity length. It is shown that the pressure pipeline properties and the cavity volume have an effect on the cavitation self-oscillation mode (up to four frequency modes can be observable at the same geometry and hydraulic flow parameters). The question arises of whether the self-oscillations can be used for generating pulsed jets at the outlet. It seems that it is the first mode regime that is most suitable for producing the pulsed jets, since in this case the pressure fluctuations in the cavity are maximum. Using the exponential Voitsekhovskii nozzle the regimes, in which an intermittent jet flow of the liquid is realized at the outlet, are experimentally obtained.

Introduction: Impression fractures of the proximal end of the tibia occupy the main place in the appearance of defor-mation of the articular surfaces. The goal is to improve the results of treatment of impression fractures of the proximal end of the shin bones, based on clarifying the volume of impression defects and filling the residual cavities. Materials and methods: The study analyzed the data of 32 patients with impression fractures of the proximal end of the tibia. The volume of the formed cavities was determined according to the program for the MSCT study (per cubic centimeter measurements). V = length *thickness *width *0.52 = cubic cm, the method by which radiation diagnostics doctors work and display the volume of the cavity in cubic centimeters. V cavity volume = cavity length *cavity thickness *cavity width *0.52 = cc / cm (0.52 is the accepted average value, standard). Results: The results were also studied according to the accepted methodology compiled by the crite-ria for evaluating the results, and they turned out to be the following in terms of the totality of the treatment performed: in 25 patients it was from 62 to 76 points, i.e. good, in 7 patients they were satis-factory, i.e. averaged 58 points, there were no unsatisfactory result. Discussion: The combined use of PRP-therapy, bone grafting or bone impregnated with platelet mass proved to be compatible in osteosynthesis of bone fragments using the Ilizarov apparatus. Conclusion: The use of modern visualization diagnostic tools determines the volume and calculations for filling bone defects.

We design extremely flexible, ultrahigh-Q, diamond-based double-heterostructure photonic crystal slab cavities by modifying the refractive index of the diamond. The refractive index changes needed for ultrahigh-Q cavities With Q similar to 10(7), are well within what can be achieved (Delta n similar to 0.02). The Q is around 30 times larger than previously reported designs in diamond. At the same time, the cavity volumes are still relatively small, at less than two cubic wavelengths. The range of parameters, cavity length and the index changes that enables an ultrahigh-Q is quite broad improving prospects for defect-tolerant quantum architectures