1pPA1 – Ammonia chemistry: Sounds better with ultrasound

Dr. Prince Nana AMANIAMPONG, prince.nana.amaniampong@univ-poitiers.fr
CNRS Chargé de Recherche (CRCN)
Bâtiment B1, Rue Marcel Doré, TSA41105
86073 – Poitiers Cedex 9 (France)

Popular version of 1pPA1 – Ammonia chemistry: Sounds better with ultrasound
Presented Monday morning, May 23, 2022
182nd ASA Meeting
Click here to read the abstract

Hydrazine (N2H4) is a chemical of outmost importance in the chemical industry. The global hydrazine market was valued at 510.95 million USD in 2020, and is projected to reach 806.09 million by 2030, mostly boosted by the growing need of our society for the manufacture of polymer foams and agrochemicals. Moreover, hydrazine is used in space vehicles in the form of propellant to reduce the overall concentration of dissolved oxygen. The direct production of hydrazine from ammonia (NH3) is economically and environmentally highly attractive, but it remains a very difficult task. One of the reason stems from the high bond dissociation energy of N-H bond in NH3 (435 kJ/mol), requiring harsh conditions of temperature and pressure, which are not compatible with the stability of hydrazine. Indeed the composition of hydrazine is thermodynamically more favorable than the conversion of ammonia to hydrazine, making the accumulation of hydrazine scientifically challenging.

In this work, we show that cavitation bubbles created by ultrasonic irradiation of aqueous NH3 at a high frequency, act as micro-reactors to activate and convert NH3 to amino species, without assistance of any catalyst, yielding hydrazine at the bubble-liquid interface (Figure 1). The compartmentation of the in-situ produced hydrazine in the bulk solution, which is maintained close to 30 °C, advantageously prevents its thermal degradation, a recurrent problem faced by previous technologies.

ammonia

Figure 1. Cavitation bubbles act as micro-reactors to activate ammonia towards hydrazine formation.

With this technology, a maximum hydrazine production rate of 0.17 mmol.L-1.h-2 in 7 wt. % ammonia solution was achieved (Figure 2). This work opens up new avenues toward the production of hydrazine for industrial and commercial applications using high frequency ultrasound activation technologies.

ammonia

Figure 2. Effect of NH3 concentration on the formation of hydrazine (525 kHz, 0.17 W/mL, 30 °C)

This is has been recently published in Angewandte Chemie International Edition, Anaelle Humblot et al., 60, 48, 25230-25234 (doi.org/10.1002/anie.202109516) and was also highlighted as the front cover image of the issue.

5pBA4 – A noninvasive ultrasound device to treat urinary stones in pet cats

Adam Maxwell – amax38@uw.edu
Ga Won Kim – gawonkim@uw.edu
Elizabeth Lynch – elynch@apl.washington.edu
Brian MacConaghy – bmacconaghy@gmail.com
Eva Furrow – furro004@umn.edu
Jody Lulich – lulic001@umn.edu
Michael Borofsky – mborofsk@umn.edu
Michael R. Bailey – mbailey@uw.edu

Corresponding Author Address:
University of Washington
1013 NE 40th Street
Seattle, WA 98105

Popular version of 5pBA4 – A burst wave lithotripsy system for urinary stones in pet cats
Presented Friday, December 03, 2021
181st ASA Meeting, Seattle, WA
Click here to read the abstract

Like humans, cats grow stones in their kidneys. As these stones pass through the urinary tract, they can become stuck and block the outflow of urine. This obstruction can cause pressure in the kidney and may lead to kidney failure, pain, and other complications. Unfortunately, the minimally invasive technologies used in humans to break apart or remove stones can’t be used on a cat. A veterinarian’s only option for definitive treatment is a complex and costly surgery.

Our team has developed a new, noninvasive method to fragment kidney stones using a handheld ultrasound transducer placed against the skin of a patient. The ultrasound travels through the body and is focused onto a stone, were the high-amplitude pressure waves cause stresses that fracture the stone to pieces that are small enough to pass naturally through the urinary tract. This technology, called burst wave lithotripsy (BWL), has been demonstrated to be effective and safe in preclinical studies, and is now being tested in clinical trials in humans. The goal of this project was to adapt the technology to cats, so that we can provide a noninvasive option for treatment of their stones.

Because of the smaller anatomy of a cat vs. a human, the ultrasound transducer was scaled to a smaller size, and focused at a shorter depth from the skin where we anticipate the stones will be located. We also changed the ultrasound frequency emitted by the transducer. This characteristic controls the size of fragments remaining after the stone is broken apart. By using a higher frequency (650 kHz in cats vs. 350 kHz in humans), the stones are broken mostly into fragments less than 1 mm. Such fragments are usually small enough to pass through the ureter (the narrow tract between the kidney and bladder) and not obstruct urine flow.

BWL system designed for cats
Figure 1. The left image shows a BWL system designed for cats. The right image shows the small, handheld head of the therapy transducer, which is placed against the cat’s skin during a procedure.

We designed and built prototypes of the transducer and the electronics that power it. An ultrasound imaging probe was incorporated so a veterinarian or radiologist operating the system can use this imaging to target the stone before breaking it apart. The system was tested on natural feline stones in a benchtop experiment. Between 73-96% of the stone mass was reduced to fragments smaller than 1 mm, indicating a high probability of success in treatments.cat kidney stone

Figure 2. An ultrasound image of a cat’s kidney with a stone (yellow arrow). Ultrasound imaging is used to detect and target a stone.

cat calcium stone
Figure 3. (Left) A 3-mm natural feline calcium stone that was exposed to BWL and broke into several small fragments after treatment.

We are now preparing to perform veterinary clinical testing. Once its benefit is demonstrated, this technology could be made available as a safer and less invasive alternative to treat obstructing stones in cats. This work supported by NIDDK P01DK043881 and the EveryCat Health Foundation.

1aBAb1 – Acoustic intra-body communication using semi-guided waves through human body tissues

John O. Gerguis – jgerguis@purdue.edu
Mayukh Nath – nathm@purdue.edu
Shreyas Sen – shreyas@purdue.edu
Purdue University
516 Northwestern Ave
West Lafayette, IN, USA 47906

Popular version of 1aBAb1 – Ultrasonic intra-body communication using semi-guided waves through human body tissues
Presented Monday morning, November 29, 2021
181st  ASA Meeting in Seattle, Washington
Read the article in Proceedings of Meetings on Acoustics

The considerable attention that the Internet of Things (IOT) received in the recent years, has led to the development of low-cost and miniaturized devices. One of the fields that had a chance to benefit from this development is the Body Area Network (BAN), which is a network across the human body used to connect wearable and implantable devices.

Traditionally, Radio Frequency signals are used for the communication between devices across the BAN, which suffer from high losses and lack of security. Recently, electro-quasistatic human body communication, that uses the body as a wire, has emerged as an alternative – enabling low-power communication, and ultra-low leakage from human body (Das et al., 2019).

Acoustic waves have a better ability than Radio Frequency waves to propagate through water-dominant media, like the human body, besides being safe and physically secured in the body. Hence, ultrasounds present a promising alternative for the communication between wearable and/or implantable devices across the BAN.

In this work, a theoretical study was presented to explore the possibility of using ultrasounds for the communication between devices attached on the body. The ultrasound waves are confined inside the human tissues (muscle, fat and skin), thus a secure communication can be achieved, making it difficult for eavesdroppers to snoop the transmitted signal. (see Figure 1).

communication

Figure 1 “Intrabody communication between wearable devices through ultrasonic waves”

The confinement is achieved by avoiding the bone, a highly-attenuative tissue (has an attenuation of almost an order of magnitude higher than the other main tissues of the body), by having a total internal reflection on the bone/muscle interface through oblique incidence of ultrasounds on that interface. From the other side, the high acoustic impedance mismatch between the air and the skin, the outer layer of the human body, allows high reflection of the signal at the skin/air interface (~99.9%), thus confining most of the signal inside the body. By using directional acoustic wave propagation through the body and using total internal reflection, besides avoiding the bone, non-line-of-sight communication can be achieved as well between wearable devices with longer separations. This communication mechanism might be suitable in regions with thick bone (e.g. the leg).

Simulations are performed at an acoustic frequency of 100 kHz on a simplified cylindrical-shaped human body model, consisting of concentric layers of the four main tissues that form the human body: bone, muscle, fat and skin.

Figure 2. Total internal reflection of the acoustic waves on the bone.

Total internal reflection on the bone is shown in Figure 2 , where a transmitter is placed in location A and the receiver should be placed in location B. Figure 3(a) shows a ray tracing for the transmitted acoustic wave from the transmitter to the receiver, while Figure 3(b) shows the power density distribution at the receiver site. A communication between wearable devices across a distance of around 1m is shown to be possible with losses < 50 dB and with leakage signal which is >20 dB below the received signal, hence making the communication secure.

Figure 3(a). Ray tracing for the transmitted acoustic waves from the transmitter to the receiver.

 Figure 3(b). Power density distribution at the receiver site.

2pCA8 – Sonic boom propagation using an improved ray tracing technique

Kimberly Riegel – kriegel@qcc.cuny.edu
William Costa
George Seaton
Christian Gomez
Queensborough Community College
222-05 56th Avenue
Bayside, NY 11364

Popular version of 2pCA8 – Sonic boom propagation in a non-homogeneous atmosphere using a stratified ray tracing technique’
Presented Tuesday afternoon, November 30, 2019
181st ASA Meeting
Click here to read the abstract

Supersonic air travel could reduce flight times by half, vastly improving long range air travel. To make this type of travel commercially viable, however, the current ban on overland flight would need to be lifted while ensuring residents below are still protected from the high noise levels in the flight paths of these new aircraft. There has been a recent increase in supersonic aircraft investment. United Airlines just invested in 15 supersonic jets provided by BOOM supersonic. These aircraft are expected to fly in 2029 but will remain restricted to over water flight. Lockheed Martin in partnership with NASA is building a low boom demonstrator aircraft. This aircraft is expected to perform some community-based test flights next year. Therefore, a computationally efficient prediction tool that can predict the impact of sonic booms in urban areas would be a useful tool for researchers and legislators.

Previously a ray tracing simulation tool to predict the sound behavior in urban environments was developed. The simulation included the ability to read in 3D renderings of the environments. This made it possible to simulate any complicated shape including detailed buildings and multiple buildings. All surfaces are represented by a mesh of triangular faces. The more complicated the building, the more triangles were required to accurately represent it. The biggest limitation of the code was that it could take several days to complete one simulation of a complicated building. The purpose of this work is to reduce the computational time to make the numerical simulation more accessible while not sacrificing the accuracy of the results.

In order to reduce the computation time for complex geometries the entire environment was cut into horizontal slices. Only the slice where the origin of the ray is considered at a time. This allows for a significant reduction in the number of building facets that needs to be assessed for each step. Figure 1 shows the total building in grey and the slice under consideration in green.

 

[IMAGE MISSING]
Figure 1. Representation of a simple building/ray interaction and the vertical slices where the building is segmented.

To determine how the modifications to the code improved the result, several environments were run and compared to those environments for previous version of the code. Table 1 shows the improvements. From the timing of the different versions of the code it is clear that updates to the code have drastically reduced the computation times for complex environments. The resulting pressures at the receivers have no noticeable difference in the pressure results. This will improve the useability of the simulation and make it more convenient to predict sonic booms in urban areas.

1aBAb – Detecting liver cracks using ultrasonic shear wave imaging

Jingfei Liu – jingfei.liu@ttu.edu
Texas Tech University
2500 Broadway
Lubbock, TX 79409

Popular version of 1aBAb – An ex vivo investigation of ultrasonic shear wave imaging for detecting liver cracks
Presented Monday morning, November 29, 2021
181st ASA Meeting
Click here to read the abstract

Liver crack is a type of liver trauma, in which a capsular tear of different geometries occurs due to external impacts, and it is a common physical damage in traffic accidents, combating sports, and other accidents. Since liver crack is an important source of morbidity and mortality in emergency medicine, a timely and accurate detection of the crack location and geometry is highly demanded. In current emergency care, ultrasonography, although has a low accuracy, is mostly used for initial examination of liver trauma due to its immediate availability, high mobility, and nonionizing nature. After the initial screening using ultrasonography, a more accurate diagnosis is normally achieved by X-ray computer tomography (CT). Although CT can provide more details of the liver damage, it is not easy to access because patients must be transport to CT facilities, and it is even risky for the patients like newborns whose condition is unstable. To develop a diagnostic technique which both has easy access and can provide accurate diagnosis, ultrasonic shear wave imaging was proposed in this study as a better option.

In this technique, shear wave, a different type of ultrasonic wave from the ultrasonic wave (longitudinal wave) used in typical ultrasonography, is first generated at the patients’ liver, and then tracked during its propagation. Because shear wave cannot propagate in blood, there will be strong reflection or diffraction at the crack locations, which ultrasonography cannot identify (because longitudinal wave can go through blood and no strong reflection is available). Thus, the location and severeness of targeted liver crack can possibly be detected.

In this study, the feasibility and effectiveness of this method was investigated in an ex vivo scenario. A porcine liver with cracks of different geometries was tested. Shear waves were generated using acoustic radiation force impulse and recorded using ultrafast ultrasound imaging. To find the best way to display the cracks, different methods of signal processing based on time-of-flight, shear wave modulus, and accumulated shear wave path were applied to the shear wave displacement extracted. The results show that shear wave imaging is a more sensitive method than the conventional ultrasonography in detecting liver cracks.