Mechanical Disturbance Research Articles

Effect of ultrasonic field on the mechanism of electrodeposited Cu nucleation and growth

Electrodeposition technology is widely used in the surface treatment of copper foil. The unique “mechanical disturbance effect” and “cavitation effect” of ultrasonic field can effectively control the electrodeposition process of Cu and improve the quality of electrodeposited layer. In this paper, Linear Sweep Voltammetry (LSV), Cyclic Voltammetry (CV), Chronoamperometry (CA) and Chronocoulometry (CC) were used to study the electrochemical behavior of electrodeposited Cu in ultra-high acidity sulfate systems under different ultrasonic field powers. The nucleation and growth mechanism of Cu were discussed, and the surface morphology of electrodeposited layer was analyzed. The results show that the electrodeposition of Cu under the static condition (0 W) follows the diffusion controlled progressive nucleation and 3D growth mechanism, and the deposits are in the cylindrical shape with spherically agglomerated. The ultrasonic field significantly improves the mass transfer rate in the electrodeposition process, and the fine dispersion effect is obvious. The uniform and dense micro-nano layers are formed, following the 3D growth mechanism. With the increasing of ultrasonic field power, the nucleation mechanism gradually changes from the diffusion controlled progressive nucleation to the electrochemistry controlled instantaneous nucleation. In addition, there appear peeling, grooving and local microcracks on the electrodeposited layer under higher ultrasonic power condition, and it is easier to form a smooth and uniform electrodeposited layer with the ultrasonic power of 60 W compared to that with the ultrasonic power of 100 W.

Impacts of vegetation and topsoil removal on soil erosion, soil moisture, and infiltration

AbstractSoil erosion by water is a critical environmental problem that affects a large land area globally and is expected to increase substantially as a result of climate change‐induced rainfall intensification. This study sought to determine the impacts of soil mechanical disturbance and topsoil removal on soil erosion and deposition, soil moisture, soil water infiltration, and vegetation type in a central Texas subtropical grassland setting. The removal of topsoil increased soil erosion and caused changes in soil texture, soil moisture, infiltration rate, and the vegetation community within the disturbed area. Soil texture shifted from clay to sand dominated as sand particles were eroded from an upland area. This shift in soil texture led to decreased volumetric soil moisture (−14.6%) as compared to an adjacent undisturbed location. The removal of topsoil also led to an invasion of non‐native grasses that now dominate the vegetated portions of the disturbed area. Erosion and deposition measurements indicated an uneven gain and loss of soil across the disturbed area, but on average 0.85 cm of sand was deposited during the 1‐month study period. Our results show that high levels of erosion are occurring and degrading the immediate landscape, which is likely contributing a large amount of sediment to a nearby waterway, posing a potential water quality threat to an important surface water body.

High-frequency line-of-sight jitter rejection via an extended Youla-Kucera parameterization controller in segmented diffractive telescope—Theory and experiment

Line-of-sight jitter caused by mechanical vibrations and disturbances in the transmission medium seriously damages the imaging performance in telescope systems. This paper investigates the problem of high-frequency line-of-sight jitter rejection up to Nyquist frequency in bandwidth-limited control systems due to time delays. Although the piezoelectric ceramic-driven tip-tilt mirror has a wide bandwidth, Large time delays caused by the image sensor for high-quality imaging severely restrict the control system’s closed-loop bandwidth. The disturbance cannot be sufficiently rejected, especially outside the bandwidth. Based on the Small Gain Theorem, the gain factor and time-delay factor as an extra flexible budget in the Youla-Kucera (Y-K) parameterization are derived from decreasing the waterbed effect, improving the closed-loop system stability. Thus, this proposed Y-K method accommodates disturbance rejection frequency inside and outside control bandwidth, which can be extended to the Nyquist frequency. Simulation analyses and Experimental results have been effectively verified in the line-of-sight stabilization control of the segmented lightweight large-scaled diffractive telescope (SLLDT) system.

Microvibration simulation of reaction wheel ball bearings

Microvibrations on board satellites are a well-known problem affecting their pointing accuracy by inducing oscillations to the line-of-sight. Fast rotating devices, such as reaction wheel assemblies (RWAs) are a major cause of these onboard mechanical disturbances. Imbalances in the flywheel, as well as imperfections in the ball-bearing components yield low-amplitude vibrations that are transmitted to the satellite structure, adversely affecting the performance of sensitive onboard instruments. This research focuses on the RWA’s ball bearing microvibration frequency and amplitude characterization. This is achieved by introducing specific geometry imperfections on the ball bearing rotating elements. In addition, variables such as the ball bearing preload, the number of balls and their dimensions are altered to understand how the bearing microvibration changes in order to minimize it. Finally, available physical microvibration test data is used to compare and cross-correlate the microvibration waterfall plots obtained from the transient FEA of the parametrized bearing models introduced herein. This work provides a better understanding of the relation between the main structural ball bearing parameters and the microvibration disturbances emitted by the RWA to minimize its mechanical noise.

Understanding Hypervolemia in Chronic Kidney Disease

Introduction: Chronic Kidney Disease (CKD) is a progressive and irreversible decline in kidney function and a decreased Glomerular Filtration Rate (GFR). Decreased kidney function contributes to decreased water excretion and fluid overload caused by decreased GFR. A progressive decrease in GFR in renal disease leads to hypertension, sodium retention, and fluid overload. Discussion: CKD is kidney damage or also defined as a decrease in glomerular filtration rate (GFR) of less than 60 ml/minute/1.73m2 that occurs for 3 months or more. CKD is most caused by Diabetes Mellitus 64.1% and Hypertension 80.7%. One clinical manifestation in patients with CKD is an increase in fluid volume (hypervolemia). Hypervolemia is one of the nursing problems in the nursing care process. Based on the Indonesian Nursing Diagnosis Standard Book, hypervolemia is an increase in intravascular, interstitial, and/or intracellular fluid volume. The etiology of hypervolemia in CKD patients is a regulatory mechanism disorder associated with decreased GFR. Signs and symptoms both major and minor in hypervolemia nursing problems show that most patients have peripheral oedema of 53.8%, the prevalence of anemia is 52.3%, the prevalence of Haemoglobin 7-10 mg/dl is 68.3%, and the prevalence of oliguria is 16.3%. One of the actual nursing diagnosis in patients with CKD is hypervolemia related to the disturbance of regulatory mechanisms (a decrease in GFR). A progressive decrease in GFR can lead to sodium and fluid retention which causes fluid balance disturbances.

Soil aggregate stability quantified by different methods is unaffected by rice straw biochar in the long term

AbstractHighly weathered tropical soils are susceptible to disaggregation due to disruptive forces like water and mechanical disturbances. However, a few studies have investigated how biochar and cropping systems together affect the aggregate stability of tropical soils. This study investigated the long‐term (∼7 years) effect of rice straw biochar on the aggregate stability of a tropical Acrisol using the dry aggregate stability (DAS) method and SLAKES (a wet aggregate stability technique), and assessed the extent of agreement or otherwise of the aggregate stability quantified by the two methods for different treatments. Maize (Zea mays L.) and okra (Abelmoschus esculentus L.) were rotated on plots amended with rice straw biochar at rates of 0, 15, and 30 Mg ha−1. Seven years after biochar amendment, bulk soil samples were collected at 0–15 cm depth for laboratory analyses. Aggregate stability was assessed by determining erodible fraction (EF) and DAS, and by quantifying the SLAKES parameters (slaking index [SI] and slaking index at 600 seconds [SI‐600]). Neither biochar nor crop type or their interaction significantly changed the soil aggregate stability assessed by the two methods (p > 0.05). The EF and DAS weakly correlated with SI and SI‐600, which could be attributed to the differences in the mechanisms underlying soil aggregate breakdown assessed by the two methods. The study highlighted that observed challenges of the SLAKES method namely, inability in some cases to detect soil aggregates and the disaggregation process could offset its advantages as a tool for rapid detection of soil structural problem areas within agricultural fields.

The Implications of Moral Neuroscience for Brain Disease: Review and Update.

The last 2 decades have seen an explosion of neuroscience research on morality, with significant implications for brain disease. Many studies have proposed a neuromorality based on intuitive sentiments or emotions aimed at maintaining collaborative social groups. These moral emotions are normative, deontological, and action based, with a rapid evaluation of intentionality. The neuromoral circuitry interacts with the basic mechanisms of socioemotional cognition, including social perception, behavioral control, theory of mind, and social emotions such as empathy. Moral transgressions may result from primary disorders of moral intuitions, or they may be secondary moral impairments from disturbances in these other socioemotional cognitive mechanisms. The proposed neuromoral system for moral intuitions has its major hub in the ventromedial prefrontal cortex and engages other frontal regions as well as the anterior insulae, anterior temporal lobe structures, and right temporoparietal junction and adjacent posterior superior temporal sulcus. Brain diseases that affect these regions, such as behavioral variant frontotemporal dementia, may result in primary disturbances of moral behavior, including criminal behavior. Individuals with focal brain tumors and other lesions in the right temporal and medial frontal regions have committed moral violations. These transgressions can have social and legal consequences for the individuals and require increased awareness of neuromoral disturbances among such individuals with brain diseases.

Stress, immune mechanisms, and mental illness: from etiology to treatment

It is now well-established that a strong relationship exists between psychiatric disorders and disturbances of immune mechanisms at different stages of life. Indeed, a derangement in the expression and function of specific immune elements may predispose and contribute to the development of different psychopathologic conditions and could also represent an important component that must be targeted by therapeutic intervention. The proposed symposium will summarize authoritatively the important recent advances on the immune mechanisms contributing to the etiology of psychiatric disorders, with a specific focus on the role of stress, and it will discuss if and how the effectiveness of therapeutic intervention may depend on the ability to regulate immune mechanisms that are altered under pathologic conditions. The symposium will unfold upon the discussion of preclinical and clinical studies addressing different aspects related to psychiatric disorders. Prof. A. Pillai (University of Texas, U.S.A.) will specifically discuss the roles of neuroinflammation and synapse loss in IFN-I signaling-mediated social deficits under chronic stress conditions. He will discuss how peripheral blockade of IFN-I signaling attenuated stress-induced neuroimmune alterations and social behavioral deficits and also the key role of complement component 3a receptor 1 (C3ar1) in these mechanisms. Along this line, Prof. M.A. Riva (University of Milan, Italy) will show how immune mechanisms and dysregulation of microglial function may contribute to the vulnerability to stress at different life stages, from adolescence to adulthood. Moreover, he will discuss how the normalization of some of these mechanisms following pharmacological intervention may contribute to therapeutic effectiveness in the treatment of different psychiatric disorders characterized, particularly in patients characterized by a higher inflammatory status. At the clinical level, Dr. G. Scaini (University of Texas, U.S.A.) will discuss the interplay between inflammation, stress, and mitochondria in bipolar disorder patients. She will highlight the significant correlation between alterations in mitochondrial proteins and inflammatory markers with a decrease in functional status and an increase in the severity of symptoms. Lastly, Prof. J. Felger (Emory Univ.) will discuss how depressed patients with increased inflammation show altered functional connectivity within the ventral striatum to ventromedial prefrontal cortex reward circuitry in relation to symptoms of anhedonia. These changes can be improved by pharmacological intervention aimed to increase dopamine levels suggesting that functional connectivity in reward circuitry may also serve as a modifiable imaging biomarker for the efficacy of pharmacological and/or behavioral interventions to reverse the impact of inflammation on the brain of depressed subjects.

Development and application of a novel approach to scoring ear tag wounds in dairy calves

Application of ear tags in cattle is a common husbandry practice for identification purposes. Although it is known that ear tag application causes damage, little is known about the duration and process of wound healing associated with this procedure. Our objective was to develop a detailed scoring system and use it to quantify wound healing in dairy calves with plastic identification tags. Calves (n = 33) were ear tagged at 2 d of age, and wound photos were taken weekly until 9 to 22 wk of age. This approach generated 10 to 22 observations per calf that were analyzed using a novel wound scoring system. We developed this system to score the presence or absence of external tissue types related to piercing trauma or mechanical irritation along the top of the tag (impressions, crust, and desquamation) and around the piercing (exudate, crust, tissue growth, and desquamation). Ears were scored as "piercing only" when tissue around the ear tag was intact. We found that impressions, crust, tissue growth, and desquamation were still seen in many calves by 12 wk of age. This suggests that extrinsic factors, such as mechanical disturbance and irritation, may have contributed to prolonged wound healing. Indeed, impressions along the top of tag, likely caused by rubbing against the ear, were observed for nearly the full duration of the study. Further research is warranted to understand ways to improve the ear-tagging process.

Morphological and Physiological Adaptations of Microbes in Root Canal Biofilms - A Literature Review

Microbial flora in the oral cavity gain entry into root canals after pulpal exposure, either due to trauma or dental caries. Once inside the root canal, bacteria of different species organize into a network and communicate with each other to withstand the chemical and physical disturbances during the treatment. They cause extraradicular infections that do not respond to conventional endodontic therapies. Bacteria present on the surface of root canals organize into a framework consisting of the matrix, bacteria, and water. The matrix consists of extracellular polysaccharide, which varies with the species that secrete them. It also contains proteins, fatty acids, and extracellular DNA, which help in the growth of the matrix, survival, and pathogenesis of organisms. Microorganisms entering the root canals should survive the nitric oxide rich, oxygen stressed, and nutrient-deprived environment. They should also resist the chemical and mechanical disturbances created during endodontic treatment to enable their persistence in the root canals. This review aims to discuss biofilm formation and the mechanisms by which it helps in bacterial survival in root canals.

The modeling of interaction between fuel element cladding and steam

This work simulates a close to emergency case in the reactor core - the material of fuel element cladding is subjected to steam flow. The presented model takes into account several processes occurring together - the admittance of oxygen and hydrogen, the propagation of heat, diffusion and mechanical disturbances, chemical reaction. The transfer mechanism of oxygen and hydrogen under the action of the stress gradient is taken into account. The model is suitable to describe the processes at very small times, corresponding to short thermal impulses and initial stages of surface interrelation with steam flow. The all short-time accompanying processes (10-9 −10-12 s) affect the changes in the material exposed to steam contact, but they are not easily accessible for direct observation. The problem was solved numerically. The temperature in our numerical experiment is not too high, but it is already sufficient for introduction of hydrogen and oxygen into the Zr-1%Nb surface, as well as for oxidation of zirconium. Examples of calculations are presented. It shows how different-scale processes interact with each other and to what distortions in the distributions of all interacting quantities this leads. Examples of calculations for different durations of vapor interaction with cladding surface are presented. It is shown that the concentration of oxygen and hydrogen in Zr alloy increases when the vapor action is too long-term.

High-Precision Small-Angle Measurement of Laser-Fiber Autocollimation Using Common-Path Polarized Light Difference

The laser autocollimation measurement method is an important technique for the precise measurement of small angles. However, the beam drift significantly affects the accuracy and stability of laser autocollimation. This paper is the first to present a laser-fiber autocollimation method for measuring small angles with the difference of common-path polarized light. In principle, this method greatly reduces the laser beam drift caused by various factors and significantly improves the measurement accuracy and stability. The effects of the factors affecting beam drift on small-angle measurement were analyzed and simulated. A corresponding measurement system was developed with the capability to measure not only small angular changes in a single object, but also relatively small angular changes between two objects, and a series of experiments were conducted. The results indicated that the angle measurement stability was improved by 90%–98% using the difference of common-path polarized light to compensate the beam drift caused by mechanical structure drift, vibration, and environmental disturbance. Extremely high measurement stability of 0.07" in 10 h and 0.04" in 2 h was obtained at 500 mm. Furthermore, the measurement system was effectively utilized to measure the thermal stability of a star sensor bracket of a satellite, yielding a thermal stability of 0.15"/°C to meet the on-orbit operational stability requirement of 0.25"/°C. Thus, this new method compensates for beam drift in the autocollimation measurement of small angle changes in a single object and relatively small angular changes between two objects.

The nervous system tunes sensorimotor gains when reaching in variable mechanical environments

Humans often move in the presence of mechanical disturbances that can vary in direction and amplitude throughout movement. These disturbances can jeopardize the outcomes of our actions, such as when drinking from a glass of water on a turbulent flight or carrying a cup of coffee while walking on a busy sidewalk. Here, we examine control strategies that allow the nervous system to maintain performance when reaching in the presence of mechanical disturbances that vary randomly throughout movement. Healthy participants altered their control strategies to make movements more robust against disturbances. The change in control was associated with faster reaching movements and increased responses to proprioceptive and visual feedback that were tuned to the variability of the disturbances. Our findings highlight that the nervous system exploits a continuum of control strategies to increase its responsiveness to sensory feedback when reaching in the presence of increasingly variable physical disturbances.

Native Function of the Bacterial Ion Channel SthK in a Sparsely Tethered Lipid Bilayer Membrane Architecture.

The plasma membrane protects the interiors of cells from their surroundings and also plays a critical role in communication, sensing, and nutrient import. As a result, the cell membrane and its constituents are among the most important drug targets. Studying the cell membrane and the processes it facilitates is therefore crucial, but it is a highly complex environment that is difficult to access experimentally. Various model membrane systems have been developed to provide an environment in which membrane proteins can be studied in isolation. Among them, tethered bilayer lipid membranes (tBLMs) are a promising model system providing a solvent-free membrane environment which can be prepared by self-assembly, is resistant to mechanical disturbances and has a high electrical resistance. tBLMs are therefore uniquely suitable to study ion channels and charge transport processes. However, ion channels are often large, complex, multimeric structures and their function requires a particular lipid environment. In this paper, we show that SthK, a bacterial cyclic nucleotide gated (CNG) ion channel that is strongly dependent on the surrounding lipid composition, functions normally when embedded into a sparsely tethered lipid bilayer. As SthK has been very well characterized in terms of structure and function, it is well-suited to demonstrate the utility of tethered membrane systems. A model membrane system suitable for studying CNG ion channels would be useful, as this type of ion channel performs a wide range of physiological functions in bacteria, plants, and mammals and is therefore of fundamental scientific interest as well as being highly relevant to medicine.

Activities of daily life of people of the third age

Introduction: Aging is a natural physiological process based on disturbances of homeostatic mechanisms and loss of adaptability that significantly affects life activities over time. The activities of daily living (ADL) in old age represent the relationship between the subjective characteristics of each individual, supplemented by previous life experiences, and objective socioeconomic factors that create a desirable living framework for people in the third age. The objectives of this research are to analyze the sociodemographic characteristics of third-age people, to study the daily activities of third-age people, and to compare the daily life activities of third-age people living in a rural setting with those of third-age people living in an urban setting. Methods: The research was conducted in the area of urban and rural environment of Travnik municipality. One hundred elderly people (50 from urban and 50 from rural areas) were included in the research using the snowball method. The instrument used in our research is a standardized questionnaire on instrumental ADL (IADL) according to Lawton-Brody. The study was conducted during the period from the end of March to the end of May 2022. Results: There is a statistically significant difference in ADL in all eight domains. The mean IADL score in the total sample (n = 100) was 6.36 ± 1.78 and ranged from 1 to 8. The largest number of respondents had the highest IADL score of 8 in 41% of cases, while only one respondent had an IADL score of 1. Conclusion: The obtained results prove that the score of ADL is lower in people of third-age living in rural areas.

In vivo endoscopic ultrasound imaging with a rotational-scanning, all-optical ultrasound probe.

All-optical ultrasound manipulates ultrasound waves based on laser and photonics technologies, providing an alternative approach for pulse-echo ultrasound imaging. However, its endoscopic imaging capability is limited ex vivo by the multifiber connection between the endoscopic probe and the console. Here, we report on all-optical ultrasound for in vivo endoscopic imaging using a rotational-scanning probe that relies on a small laser sensor to detect echo ultrasound waves. The acoustically induced lasing frequency change is measured via heterodyne detection by beating the two orthogonally polarized laser modes, enabling a stable output of ultrasonic responses and immunity to low-frequency thermal and mechanical disturbances. We miniaturize its optical driving and signal interrogation unit and synchronously rotate it with the imaging probe. This specialized design leaves a single-fiber connection to the proximal end and allows fast rotational scanning of the probe. As a result, we used a flexible, miniature all-optical ultrasound probe for in vivo rectal imaging with a B-scan rate of 1 Hz and a pullback range of ∼7 cm. This can visualize the gastrointestinal and extraluminal structures of a small animal. This imaging modality offers an imaging depth of 2 cm at a central frequency of ∼20 MHz, showing promise for high-frequency ultrasound imaging applications in gastroenterology and cardiology.

Disturbance induces similar shifts in arbuscular mycorrhizal fungal communities from grassland and arable field soils.

Anthropogenic disturbances play an increasingly important role in structuring the diversity and functioning of soil organisms such as arbuscular mycorrhizal (AM) fungi. Frequently, multiple land-use practices, which may represent disturbances for AM fungal communities, operate simultaneously in different habitats. It is not known, however, how previous land-use history and specific habitat type influence AM fungal community response to disturbances. We applied mechanical (cutting to stimulate tillage) and chemical (herbicide addition) disturbances to AM fungal communities from meadow and arable field soils. Our results indicated that AM fungal communities from meadows, which previously had experienced mowing, were more species rich than communities from fields that had experienced intensive land-use practices. There were no significant differences, however, in the responses to disturbance of the AM fungal communities from field and meadow soils. We expected mechanical disturbance to promote taxa from the family Glomeraceae which are expected to exhibit a ruderal life-history strategy; instead, the abundance of this family increased in response to chemical disturbance. Simultaneous application of mechanical disturbance and herbicide decreased only the abundance of Diversisporaceae. No AM fungal families increased in abundance when both mechanical and chemical disturbances were applied simultaneously, but all disturbances increased the abundance of culturable AM fungi. Our study demonstrates that although chemical and mechanical forms of disturbance favor different AM fungal families, existing information about family-level characteristics may not adequately characterize the life history strategies of AM fungus species.

Mechanical disturbances applied by motorized ankle foot orthosis to adapt ankle muscles activation-A validation study.

Background: Reduced function of ankle muscles usually leads to impaired gait. Motorized ankle foot orthoses (MAFOs) have shown potential to improve neuromuscular control and increase volitional engagement of ankle muscles. In this study, we hypothesize that specific disturbances (adaptive resistance-based perturbations to the planned trajectory) applied by a MAFO can be used to adapt the activity of ankle muscles. The first goal of this exploratory study was to test and validate two different ankle disturbances based on plantarflexion and dorsiflexion resistance while training in standing still position. The second goal was to assess neuromuscular adaptation to these approaches, namely, in terms of individual muscle activation and co-activation of antagonists. Methods: Two ankle disturbances were tested in ten healthy subjects. For each subject, the dominant ankle followed a target trajectory while the contralateral leg was standing still: a) dorsiflexion torque during the first part of the trajectory (Stance Correlate disturbance-StC), and b) plantarflexion torque during the second part of the trajectory (Swing Correlate disturbance-SwC). Electromyography was recorded from the tibialis anterior (TAnt) and gastrocnemius medialis (GMed) during MAFO and treadmill (baseline) trials. Results: GMed (plantarflexor muscle) activation decreased in all subjects during the application of StC, indicating that dorsiflexion torque did not enhance GMed activity. On the other hand, TAnt (dorsiflexor muscle) activation increased when SwC was applied, indicating that plantarflexion torque succeeded in enhancing TAnt activation. For each disturbance paradigm, there was no antagonist muscle co-activation accompanying agonist muscle activity changes. Conclusion: We successfully tested novel ankle disturbance approaches that can be explored as potential resistance strategies in MAFO training. Results from SwC training warrant further investigation to promote specific motor recovery and learning of dorsiflexion in neural-impaired patients. This training can potentially be beneficial during intermediate phases of rehabilitation prior to overground exoskeleton-assisted walking. Decreased activation of GMed during StC might be attributed to the unloaded body weight in the ipsilateral side, which typically decreases activation of anti-gravity muscles. Neural adaptation to StC needs to be studied thoroughly in different postures in futures studies.

Robust backstepping control for maneuver aircraft based on event-triggered mechanism and nonlinear disturbance observer

PurposeThis study aims to achieve the post-stall pitching maneuver (PSPM) and decrease the deflection frequency of aircraft actuators controlled by the robust backstepping method based on event-triggered mechanism (ETM), nonlinear disturbance observer (NDO) and dynamic surface control (DSC) techniques.Design/methodology/approachTo estimate unsteady aerodynamic disturbances (UADs) to suppress their adverse effects, the NDO is designed. To avoid taking the derivative of the virtual control law directly and eliminate the coupling term of the system states and dynamic surface errors in the stability analysis, an improved DSC is developed. Combined with the NDO and DSC techniques, a robust backstepping method is proposed to achieve the PSPM. Furthermore, to decrease the deflection frequency of the aircraft actuators, a state-dependent ETM is introduced.FindingsAn ETM-and-NDO-based backstepping method with an improved DSC technique is developed to achieve the PSPM and decrease the deflection frequency of aircraft actuators. And simulation results are presented to verify the effectiveness of the proposed paper.Originality/valueFew studies have been conducted on the control of the PSPM in which the lateral and longitudinal attitude dynamics are coupled with each other considering the UADs. Moreover, the mechanism that can decrease the deflection frequency of aircraft actuators is rarely developed in existing research. This study proposes an ETM-and-NDO-based backstepping scheme to address these problems with satisfactory performance of the PSPM.

Remote-refocusing light-sheet fluorescence microscopy enables 3D imaging of electromechanical coupling of hiPSC-derived and adult cardiomyocytes in co-culture

Improving cardiac function through stem-cell regenerative therapy requires functional and structural integration of the transplanted cells with the host tissue. Visualizing the electromechanical interaction between native and graft cells necessitates 3D imaging with high spatio-temporal resolution and low photo-toxicity. A custom light-sheet fluorescence microscope was used for volumetric imaging of calcium dynamics in co-cultures of adult rat left ventricle cardiomyocytes and human induced pluripotent stem cell-derived cardiomyocytes. Aberration-free remote refocus of the detection plane synchronously to the scanning of the light sheet along the detection axis enabled fast dual-channel 3D imaging at subcellular resolution without mechanical sample disturbance at up to 8 Hz over a ∼300 µm × 40 µm × 50 µm volume. The two cell types were found to undergo electrically stimulated and spontaneous synchronized calcium transients and contraction. Electromechanical coupling improved with co-culture duration, with 50% of adult-CM coupled after 24 h of co-culture, compared to 19% after 4 h (p = 0.0305). Immobilization with para-nitroblebbistatin did not prevent calcium transient synchronization, with 35% and 36% adult-CM coupled in control and treated samples respectively (p = 0.91), indicating that electrical coupling can be maintained independently of mechanotransduction.