Utilizing passive elements to break time reversibility at low Reynolds number: a swimmer with one activated element.

In the realm of low Reynolds number, the shape-changing biological and artificial matters need to break time reversibility in the course of their strokes to achieve motility. This necessity is well described in the so-called scallop theorem. In this work, considering low Reynolds number, a novel and versatile swimmer is proposed as an example of a new scheme to break time reversibility kinematically and, in turn, produce net motion. The swimmer consists of one sphere as a cargo or carried body, joined by one activated link with time-varying length, to another perpendicular rigid link, as the support of two passively flapping disks, at its end. The disks are free to rotate between their fixed minimum and maximum angles. The system's motion in two dimensions is simulated, and the maneuverability of the swimmer is discussed. The minimal operating parameters for steering of the swimmer are studied, and the limits of the swimmer are identified. The introduced swimming mechanism can be employed as a simple model system for biological living matters as well as artificial microswimmers.

Preliminary report of Iranian Registry of Alzheimer's disease in Tehran province: A cross-sectional study in Iran.

Background and Aims: Alzheimer's disease (AD) is the main cause of dementia and over the 55 million people live with dementia worldwide. We aimed to establish the first database called the Iranian Alzheimer's Disease Registry to create a powerful source for future research in the country. In this report, the design and early results of the Iranian Alzheimer's Disease Registry will be described. Methods: We performed this multicenter investigation and patients' data including age, sex, educational level, disease status, Mini-Mental State Examination (MMSE), and Geriatric Depression Scale (GDS) from 2018 to 2021 were collected, registered, and analyzed by GraphPad Prism software. Results: Totally 200 AD patients were registered in our database. 107 (54%) were women and age of 147 (74%) were over 65. The mean age for men and women was 76.20 ± 8.29 and 76.40 ± 8.83 years, respectively. 132 (66%) were married and 64 (32%) were illiterate. Also, 94 (47%) were in the moderate stage of disease, and 150 (75%) lived at home together with their families. The most frequent neurological comorbidity was psychosis (n = 72, 36%), while hypertension was the most common non-neurological comorbidity (n = 104, 52%). The GDS score of women in the mild stage (5.23 ± 2.9 vs. 6.9 ± 2.6, p = 0.005) and moderate stage (5.36 ± 2.4 vs. 8.21 ± 2.06, p = <0.001) of the disease was significantly greater than men. In univariate analysis, MMSC score was remarkably associated with stroke (ß = -2.25, p = 0.03), psychosis (ß = -2.18, p = 0.009), diabetes (ß = 3.6, p = <0.001), and hypercholesteremia (ß = 1.67, p = 0.05). Also, the MMSE score showed a notable relationship with stroke (ß = -2.13, p = 0.05) and diabetes (ß = 3.26, p = <0.001) in multivariate analysis. Conclusion: Iranian Alzheimer's Disease Registry can provide epidemiological and clinical data to use for purposes such as enhancing the current AD management in clinical centers, filling the gaps in preventative care, and establishing effective monitoring and cure for the disease.

Acoustic steering of active spherical carriers.

Following the novel introduced concept of the active carriers, this paper brings forward a technique toward the manipulability of an internally piezo-equipped active spherical carrier subjected to the progressive acoustic plane waves as the handling contactless asset. It is assumed that the piezoelectric part of the active carrier may be actuated as a bi-sectional body (i.e., two continuous hemispherical parts), with prescribed phase difference, and the polar position of the imaginary separating plane may be altered. This issue brings about an asymmetry in the dynamics of the problem which leads to emergence of position/frequency dependent acoustic radiation torque. It is obtained that as the carrier is excited by imposing harmonic voltage with the same amplitude and a π-radians phase difference, the zero-radiation force situation is obtained for a specific amplitude and phase of voltage as a function of frequency. This situation is treated as a criterion to determine the optimal amplitude of operation voltage. It is shown that the net force's direction exerted on the activated carrier may be steered along any desired orientation, assuming the fixed direction of incident wave field. The explained method of excitation and controllability of the spatial position of the divisor plane can possibly be a breakthrough in acoustic handling of active carriers. Noticeably, by this new technique, the single beam acoustic based contact-free methods and their applications in association with the concept of active carriers are now one step forward.

Ultrasound focuser: A multi-cylindrical source configuration and entrapped particles dynamics.

We aim to introduce the proof of concept of a 3D ultrasound Focuser with possible advanced applications in living-matter/cell entrapment, particle focusing, transportation through virtual channel and drug, agent or material delivery systems. The proposed mechanism is assumed to be fully submerged in a fluidic environment and composed of three parallel acoustic line sources which are located in such a way that form a triangular right prism. By approximating the wave field of each cylindrical source as a progressive plane wave field whose amplitude decreases with respect to the travelling distance from the source, the acoustic radiation force exerted on a single particle is analytically derived. It is shown that when each source has a π/3 phase different from other sources, an attracting zone around the axis of the triangular prism is formed for wavelengths in the order of the size scale, λ/l∼O(1), where l denotes the distance between each two sources. The optimal operating situation (the largest attracting zone) is found for the case where λ≈l. The theoretical study is supported by stability analysis of dynamics of the entrapped particle which located on the axis of the prism; and validated by computing the trajectories of migration of the test particle. The stability analysis is performed by considering the unsteady solution of Stokes equations and the possible flow of environmental fluid medium. In addition, the required settling time and required length scales to focus the particle to the center line of the prism for different size scale ratios are estimated and discussed. Compared to other 3D focusing techniques, this method is non-invasive, robust, easy to implement, applicable to nearly all types of micro-particles and does not need any specific pre-designed channel for focusing process.

Self-motile swimmers: Ultrasound driven spherical model.

The concept of ultrasound acoustic driven self-motile swimmers which is the source of autonomous propulsion is the acoustic field generated by the swimmer due to the partial oscillation of its surface is investigated. Limiting the subject to a body with simple spherical geometry, it is analytically shown that the generated acoustic radiation force due to induction by asymmetric acoustic field in host medium is non-zero, which propels the device. Assuming low Reynolds number condition, the frequency-dependent swimming velocity is calculated as a function of design parameters and optimum operating condition is obtained. The proposed methodology will open a new path towards the micro- or molecular-sized self propulsive machines or mechanism with great applications in engineering, medicine and biology.

Acoustic radiation force control: Pulsating spherical carriers.

The interaction between harmonic plane progressive acoustic beams and a pulsating spherical radiator is studied. The acoustic radiation force function exerted on the spherical body is derived as a function of the incident wave pressure and the monopole vibration characteristics (i.e., amplitude and phase) of the body. Two distinct strategies are presented in order to alter the radiation force effects (i.e., pushing and pulling states) by changing its magnitude and direction. In the first strategy, an incident wave field with known amplitude and phase is considered. It is analytically shown that the zero- radiation force state (i.e., radiation force function cancellation) is achievable for specific pulsation characteristics belong to a frequency-dependent straight line equation in the plane of real-imaginary components (i.e., Nyquist Plane) of prescribed surface displacement. It is illustrated that these characteristic lines divide the mentioned displacement plane into two regions of positive (i.e., pushing) and negative (i.e., pulling) radiation forces. In the second strategy, the zero, negative and positive states of radiation force are obtained through adjusting the incident wave field characteristics (i.e., amplitude and phase) which insonifies the radiator with prescribed pulsation characteristics. It is proved that zero radiation force state occurs for incident wave pressure characteristics belong to specific frequency-dependent circles in Nyquist plane of incident wave pressure. These characteristic circles divide the Nyquist plane into two distinct regions corresponding to positive (out of circles) and negative (in the circles) values of radiation force function. It is analytically shown that the maximum amplitude of negative radiation force is exactly equal to the amplitude of the (positive) radiation force exerted upon the sphere in the passive state, by the same incident field. The developed concepts are much more deepened by considering the required power supply for distinct cases of zero, negative and positive radiation force states along with the frequency dependent asymmetry index. In addition, considering the effect of phase difference between the incident wave field and the pulsating object, and its possible variation with respect to spatial position of object, some practical points about the spatial average of generated radiation force, the optimal state of operation, the stability of zero radiation force states and the possibly of precise motion control are discussed. This work would extend the novel concept of smart carriers to and may be helpful for robust single-beam acoustic handling techniques. Furthermore, the shown capability of precise motion control may be considered as a new way toward smart acoustic driven micro-mechanisms and micro-machines.

Acoustic manipulation: Bessel beams and active carriers.

In this paper, we address the interaction of zero-order acoustic Bessel beams as an acoustic manipulation tool, with an active spherical shell, as a carrier in drug, agent, or material delivery systems, in order to investigate the controllability of exerted acoustic radiation force as the driver. The active body is comprised of a spherical elastic shell stimulated in its monopole mode of vibrations with the same frequency as the incident wave field via an internally bonded and spatially uniformly excited piezoelectric actuator. The main aim of this work is to examine the performance of a nondiffracting and self-reconstructing zero-order Bessel beam to obtain the full manipulability condition of active carriers in comparison with the case of a plane wave field. The results unveil some unique potentials of the Bessel beams in the company of active carriers, with emphasis on the consumed power of the actuation system. This paper will widen the path toward the single-beam robust acoustic manipulation techniques and may lead to the prospect of combined tweezers and fields, with applications in delivery systems, microswimmers, and trapper designs.

Protective effects of Ephedra pachyclada extract on mouse models of carbon tetrachloride- induced chronic and acute liver failure.

Inflammation and oxidation are two important factors in the pathogenesis of liver. Ephedra pachyclada (EP) is a traditional medical herb that has anti-inflammatory and anti-oxidant activities. During this study, anti-oxidant activities of the EP extract was measured in vitro by 2,2'- diphenyl-1-picrylhydrazyl (DPPH) and ß-Carotene bleaching assays. Then, we examined possible in vivo hepatoprotective effects of EP extract on mouse models of carbon tetrachloride (CCl4)-induced chronic and acute liver failure. To produce mouse models of chronic and acute liver injuries, male SW1 mice were interaperitoneally injected with 1ml/kg body weight (bw) CCl4 biweekly for 42 days and a single dose of 2ml/kg bw, respectively. In the experimental groups, mouse models were treated with low (140mg/kg bw) and high (1400mg/kg bw) doses of the EP extract. Olive oil and water treated mice were considered as controls during model derivation and EP extract treatment respectively. The results showed the antioxidant activity of EP extract and a significant reduction of all parameters of CCl4-induced liver injury such as relative liver weight, necrosis, fibrosis, inflammation, and serum aspartate transaminase (AST) and alanine aminotransferase (ALT) in mouse models of acute and chronic liver injury treated with EP extract. Therefore, EP induces its hepatoprotective effects probably by suppressing oxidative stress and inhibit inflammation in the liver and is able to protect the liver against CCl4-induced acute and chronic injuries.

An exploration in acoustic radiation force experienced by cylindrical shells via resonance scattering theory.

In nonlinear acoustic regime, a body insonified by a sound field is known to experience a steady force that is called the acoustic radiation force (RF). This force is a second-order quantity of the velocity potential function of the ambient medium. Exploiting the sufficiency of linear solution representation of potential function in RF formulation, and following the classical resonance scattering theorem (RST) which suggests the scattered field as a superposition of the resonant field and a background (non-resonant) component, we will show that the radiation force is a composition of three components: background part, resonant part and their interaction. Due to the nonlinearity effects, each part contains the contribution of pure partial waves in addition to their mutual interaction. The numerical results propose the residue component (i.e., subtraction of the background component from the RF) as a good indicator of the contribution of circumferential surface waves in RF. Defining the modal series of radiation force function and its components, it will be shown that within each partial wave, the resonance contribution can be synthesized as the Breit-Wigner form for adequately none-close resonant frequencies. The proposed formulation may be helpful essentially due to its inherent value as a canonical subject in physical acoustics. Furthermore, it may make a tunnel through the circumferential resonance reducing effects on radiation forces.

Treatment of Lymphedema Praecox through Low Level Laser Therapy (LLLT).

A 15-year-old girl with right lower extremity lymphedema praecox was treated through Low Level Laser Therapy (LLLT), by means of a GaAs and GaAlAs diodes laser-therapy device. Treatment sessions were totally 24, each cycle containing 12 every other day 15-minute sessions, and one month free between the cycles. The treatment was achieved to decrease the edema and no significant increase in circumference of involved leg was found following three months after the course of treatment. Although LLLT can be considered a beneficial treatment for Lymphedema Praecox, any definite statement around its effectiveness needs more studies on more cases.