Sema3A alleviates viral myocarditis by modulating SIRT1 to regulate cardiomyocyte mitophagy.

Viral myocarditis (VMC) is a common myocardial inflammatory disease characterized by inflammatory cell infiltration and cardiomyocyte necrosis. Sema3A was reported to reduce cardiac inflammation and improve cardiac function after myocardial infarction, but its role in VMC remains to be explored. Here, a VMC mouse model was established by infection with CVB3, and Sema3A was overexpressed in vivo by intraventricular injection of an adenovirus-mediated Sema3A expression vector (Ad-Sema3A). We found that Sema3A overexpression attenuated CVB3-induced cardiac dysfunction and tissue inflammation. And Sema3A also reduced macrophage accumulation and NLRP3 inflammasome activation in the myocardium of VMC mice. In vitro, LPS was used to stimulate primary splenic macrophages to mimic the macrophage activation state in vivo. Activated macrophages were co-cultured with primary mouse cardiomyocytes to evaluate macrophage infiltration-induced cardiomyocyte damage. Ectopic expression of Sema3A in cardiomyocytes effectively protected cardiomyocytes from activated macrophage-induced inflammation, apoptosis, and ROS accumulation. Mechanistically, cardiomyocyte-expressed Sema3A mitigated macrophage infiltration-caused cardiomyocyte dysfunction by promoting cardiomyocyte mitophagy and hindering NLRP3 inflammasome activation. Furthermore, NAM (a SIRT1 inhibitor) reversed the protective effect of Sema3A against activated macrophage-induced cardiomyocyte dysfunction by suppressing cardiomyocyte mitophagy. In conclusion, Sema3A promoted cardiomyocyte mitophagy and suppressed inflammasome activation by regulating SIRT1, thereby attenuating macrophage infiltration-induced cardiomyocyte injury in VMC.

A Graph-Based Hybrid Reconfiguration Deformation Planning for Modular Robots.

The self-reconfigurable modular robotic system is a class of robots that can alter its configuration by rearranging the connectivity of their component modular units. The reconfiguration deformation planning problem is to find a sequence of reconfiguration actions to transform one reconfiguration into another. In this paper, a hybrid reconfiguration deformation planning algorithm for modular robots is presented to enable reconfiguration between initial and goal configurations. A hybrid algorithm is developed to decompose the configuration into subconfigurations with maximum commonality and implement distributed dynamic mapping of free vertices. The module mapping relationship between the initial and target configurations is then utilized to generate reconfiguration actions. Simulation and experiment results verify the effectiveness of the proposed algorithm.

Design and Control of a Series-Parallel Elastic Actuator for a Weight-Bearing Exoskeleton Robot.

Weight-bearing exoskeletons are robots that need to carry loads and interact with humans frequently. Therefore, the actuators of these exoskeletons are supposed to be capable of outputting sufficient force with high compliance and little weight. A series-parallel elastic actuator (SPEA) is designed, in this work, to meet the demanding requirements of an exoskeleton robot called PALExo. A gas spring is installed in parallel with an electric cylinder to adjust the force output range of the actuator according to the needs of the exoskeleton. A series elastic module (SEM) is installed in series with the electric cylinder and gas spring to improve the compliance of the actuator, the stiffness of which is variable to adapt to the different stiffness requirements of the exoskeleton's legs in the standing phase and swinging phase. A force controller combining dynamic compensation and a cascade control with an inner velocity loop and a disturbance observer is designed for the SPEA. The performance of the force controller is verified by experiments and the results demonstrate that the controller has good adaptability to the stiffness of the SEM.

Modular Robotic Limbs for Astronaut Activities Assistance.

In order to meet the assist requirements of extravehicular activity (EVA) for astronauts, such as moving outside the international space station (ISS) or performing on-orbit tasks by a single astronaut, this paper proposes an astronaut robotic limbs system (AstroLimbs) for extravehicular activities assistance. This system has two robotic limbs that can be fixed on the backpack of the astronaut. Each limb is composed of several basic module units with identical structure and function, which makes it modularized and reconfigurable. The robotic limbs can work as extra arms of the astronaut to assist them outside the space station cabin. In this paper, the robotic limbs are designed and developed. The reinforcement learning method is introduced to achieve autonomous motion planning capacity for the robot, which makes the robot intelligent enough to assist the astronaut in unstructured environment. In the meantime, the movement of the robot is also planned to make it move smoothly. The structure scene of the ISS for extravehicular activities is modeled in a simulation environment, which verified the effectiveness of the proposed method.

Tripping Avoidance Lower Extremity Exoskeleton Based on Virtual Potential Field for Elderly People.

Tripping is a common problem that everyone faces when walking. This paper mainly focuses on a lower limb exoskeleton that can help those weak in joints to avoid tripping when negotiating stairs or stepping over obstacles. This method does not need a camera or map reconstruction to recognize the obstacles and plan paths. The exoskeleton applies an impedance controller to follow and control the pilot's movements. A virtual potential field is proposed to help the robot regulate the pilot's motion and avoid kicking the obstacles appearing in front of the pilot's foot during walking. Simulation and experiments show that this method works effectively and could help the elderly and those affected by joint weakness avoid tripping when walking.

Monocular Vision-Based Pose Determination in Close Proximity for Low Impact Docking.

Pose determination in close proximity is critical for space missions in which monocular vision is one of the most promising solutions. Although numerous approaches such as using artificial beacons or specific shapes on spacecrafts have proved to be effective, the high individuation and the large time delay limit their use in low impact docking. This paper proposes a unified framework to determinate the relative pose between two docking mechanisms by treating their guide petals as measurement objects. Fusing the pose information of one docking mechanism to simplify image processing and creating an intermediate coordinate system to solve the perspective-n-point problem greatly improve the real-time performance and the robustness of the method. Experimental results show that the position measurement error is within 3.7 mm, while the rotation error around docking direction is less than 0.16°, corresponding to a measurement time reduction of 85%.

Towards the Exploitation of Physical Compliance in Segmented and Electrically Actuated Robotic Legs: A Review Focused on Elastic Mechanisms.

Physical compliance has been increasingly used in robotic legs, due to its advantages in terms of the mechanical regulation of leg mechanics and energetics and the passive response to abrupt external disturbances during locomotion. This article presents a review of the exploitation of physical compliance in robotic legs. Particular attention has been paid to the segmented, electrically actuated robotic legs, such that a comparable analysis can be provided. The utilization of physical compliance is divided into three main categories, depending on the setting locations and configurations, namely, (1) joint series compliance, (2) joint parallel compliance, and (3) leg distal compliance. With an overview of the representative work related to each category, the corresponding working principles and implementation processes of various physical compliances are explained. After that, we analyze in detail some of the structural characteristics and performance influences of the existing designs, including the realization method, compliance profile, damping design, and quantitative changes in terms of mechanics and energetics. In parallel, the design challenges and possible future works associated with physical compliance in robotic legs are also identified and proposed. This article is expected to provide useful paradigmatic implementations and design guidance for physical compliance for researchers in the construction of novel physically compliant robotic legs.

Rosmarinic Acid suppressed high glucose-induced apoptosis in H9c2 cells by ameliorating the mitochondrial function and activating STAT3.

Mitochondrial injury characterized by intracellular reactive oxygen species (ROS) accumulation plays a critical role in hyperglycemia-induced myocardium dysfunction. Previous studies have demonstrated that Rosmarinic Acid (RA) treatment and activating Signal transducer and activator of transcription 3 (STAT3) signaling pathway have protective effects on mitochondrial dysfunction in cardiomyocyte, but there is little data regarding cardiomyocyte under condition of high-glucose. The present study was undertaken to determine the relationship between RA and STAT3 activation, as well as their effects on high glucose-induced mitochondrial injury and apoptosis in H9c2 cardiomyocyte. Our results revealed that RA pretreatment suppressed high glucose-induced apoptosis in H9c2 cells. Moreover, the effect of RA on apoptosis was related with improved mitochondrial function, which was demonstrated by that RA attenuated high glucose-induced ROS generation, inhibited mitochondrial permeability transition pore (MPTP) activation, suppressed cytochrome c release and caspase-3 activation. In addition, the phosphorylation of STAT3 in H9c2 cells was inhibited under condition of high-glucose, but RA improved STAT3 phosphorylation. Importantly, inhibition of STAT3 expression by using STAT3-siRNA partly suppressed the effect of RA on high glucose-induced apoptosis. Taken together, pretreatment with RA suppressed high glucose-induced apoptosis in cardiomyocyte by ameliorating mitochondrial function and activating STAT3.

[Progressive Risks of Latent Keshan Disease: a Long Term Follow-up Study].

OBJECTIVE: To observe ten-year prognosis of patients with latent Keshan disease (KD) and to determine its associated risk factors. METHODS: A total of 448 patients with newly diagnosed latent KD were monitored and followed up for 10 years. Their ECG abnormalities were classified as major or minor using the Minnesota Code. COX proportional hazards regression models were established to identify risk factors associated with the development of chronic KD. RESULTS: A final sample of 414 cases was included in analyses, with an average of (112.9 ± 17.5) months of follow-up. At the end of follow-up, 92 (22. 2%) patients developed chronic KD. Older age (> 15 years), male, family history of KD, smoking, lower level of blood selenium (< 60 µg/L), major ECG abnormalities, and 18.5 kg/m² ≤ body mass index (BMI) 23.9 kg/m² were associated with higher cumulative incidence of chronic KD. The COX regression models showed that major ECG abnormalities, BMI, selenium deficiency, hypertension, and ventricular premature complex (VPC) abnormalities contributed to increased risk of chronic KD. A positive linear correlation (r = 0.719, P < 0.01) between GPx activity and blood selenium concentration was found. CONCLUSION: Major ECG abnormalities, BMI, selenium deficiency, hypertension and VPC abnormalities are associated with the development of chronic KD.

[The establishment and identification of GPx-1(P198L) gene systemic expression transgenic mice].

OBJECTIVE: To generate systemic expression human cellular glutathione peroxidase-1 (GPx-1) (198Leu) transgenic mice model in order to investigate the functional variants in GPx-1 gene in oxidative stress-related diseases. METHODS: After linearization with BamnH I and Acc I, the transgenic construct GPx-1 (198Leu) was microinjected into the zygotes of C57BL/6J mice to generate transgenic mice, whose genotype was detected by PCR with specific primers. The GPx-1 gene expression profile was determined by Western blotting. RESULTS: 13 transgenic founder mice were successfully generated. Western blotting result showed that the protein expression level of 4 transgenic mice in hearts were higher than that of wild type mice. CONCLUSION: Human GPx-1PSL transgenic mice was successfully established. This kind of animal model is of significance for making further researches on oxidative stress-related diseases.

Calreticulin is localized at mitochondria of rat cardiomyocytes and affected by furazolidone.

Calreticulin (CRT) is a calcium-buffering protein which is predominantly located in endoplasmic reticulum. In the previous mitochondria proteome analysis, we accidentally found that CRT may be also localized at myocardial mitochondria and was upregulated in a rat model of furazolidone-induced dilated cardiomyopathy. To our knowledge, there has not yet been any report of its presence in mitochondria of any cell types. The present study aimed to determine whether CRT was located at the mitochondria of rat cardiomyocytes and whether the mitochondrial CRT was affected by furazolidone. Mitochondrial preparations were isolated from primary cultured neonatal rat cardiomyocytes and purified by differential centrifugation. The purity of mitochondria was assessed by the reduction or elimination of the immunoreactivities of markers for cytosol, nucleus, sarcolemma, and endoplasmic reticulum. Western blot analysis demonstrated the presence of CRT in purified mitochondria of rat cardiomyocytes. The distribution of CRT to mitochondria was further confirmed by immuno-electron microscopy, flow cytometry, and laser scanning confocal microscopy (double staining with MitoTracker Red and CRT-Alexa Fluor 488). Western blot analysis also demonstrated that the mitochondrial content of CRT was significantly enhanced by furazolidone treatment by 2.73 ± 0.13 fold (P < 0.05) in rat cardiomyocytes, which was verified by immuno-electron microscopy. In summary, the present results suggest that CRT is localized at mitochondria of rat cardiomyocytes and such localization is affected by furazolidone.

Mitochondrial-related gene expression profiles suggest an important role of PGC-1alpha in the compensatory mechanism of endemic dilated cardiomyopathy.

Keshan disease (KD) is an endemic dilated cardiomyopathy with unclear etiology. In this study, we compared mitochondrial-related gene expression profiles of peripheral blood mononuclear cells (PBMCs) derived from 16 KD patients and 16 normal controls in KD areas. Total RNA was isolated, amplified, labeled and hybridized to Agilent human 4 × 44k whole genome microarrays. Mitochondrial-related genes were screened out by the Third-Generation Human Mitochondria-Focused cDNA Microarray (hMitChip3). Quantitative real-time PCR, immunohistochemical and biochemical parameters related mitochondrial metabolism were conducted to validate our microarray results. In KD samples, 34 up-regulated genes (ratios ≥ 2.0) were detected by significance analysis of microarrays and ingenuity systems pathway analysis (IPA). The highest ranked molecular and cellular functions of the differentially regulated genes were closely related to amino acid metabolism, free radical scavenging, carbohydrate metabolism, and energy production. Using IPA, 40 significant pathways and four significant networks, involved mainly in apoptosis, mitochondrion dysfunction, and nuclear receptor signaling were identified. Based on our results, we suggest that PGC-1alpha regulated energy metabolism and anti-apoptosis might play an important role in the compensatory mechanism of KD. Our results may lead to the identification of potential diagnostic biomarkers for KD in PBMCs, and may help to understand the pathogenesis of KD.

Long-term prognostic value of major and minor ECG abnormalities in latent Keshan disease with suspect chronic Keshan disease.

OBJECTIVE: This study aims to determine whether baseline electrocardiography (ECG) abnormalities, the appearance of new ECG abnormalities, or other clinical characteristics are associated with increased rates of progression to chronic Keshan disease (KD) among patients with latent KD. METHODS: Four hundred and fourteen new latent KD patients from a monitored population in China were diagnosed and then followed for 10 years. Baseline and 10-year ECG abnormalities were classified according to the Minnesota Code as major and minor. Using Cox proportional hazards regression models, the addition of ECG abnormalities to traditional risk factors were examined to predict chronic KD events. RESULTS: In 414 latent KD patients with ECG abnormalities, 220 (53.1%) had minor and 194 (46.9%) had major ECG abnormalities. During the follow-up, 92 (22.2%) patients experienced chronic KD events; 32 (14.5%) and 60 (30.9%) of these chronic KD events occurred in the minor and major ECG abnormalities groups, respectively. After adjustment for baseline potential confounders, the hazard ratios and 95% confidence intervals (CIs) for progression to chronic KD in latent KD patients with major ECG abnormalities versus those with minor ECG abnormalities was 2.43 (95% CI 1.58-3.93). CONCLUSIONS: Major ECG abnormalities and new ventricular premature complex abnormalities that occurred during the follow-up were both associated with an increased risk of progression to chronic KD. Atrial fibrillation and right bundle branch block with left anterior hemiblock are the most strongly predictive components of major ECG abnormalities. Depending on the model, adding ECG abnormalities to traditional risk factors was associated with improved risk prediction in latent KD.

[Effects of p66shc adapter protein and estrogen on cardiomyocyte apoptosis induced by angiotensin II].

OBJECTIVE: To explore the role of p66shc in cardiomyocyte apoptosis induced by angiotensin (Ang) II and the effect of estrogen pretreatment. METHODS: Neonatal rat cardiomyocytes were randomly divided into five groups: normal control, 10(-11) mol/L Ang II, 10(-9) mol/L Ang II, 10(-7) mol/L Ang II, and 10(-7) mol/L Ang II + estrogen treated groups. The cell viability was measured by MTT. The level of reactive oxygen species (ROS) and cell apoptosis rate were measured by flow cytometry. Mitochondrial membrane potential (MMP) was detected using a fluorescence microplate reader, and the protein expression of phosphorylated and total p66shc were detected using Western blot. RESULTS: With the increase of Ang II concentrations, cell viabilities and MMP levels decreased, whereas, the levels of ROS and cell apoptosis rates increased (P < 0.05). Pretreatment with estrogen significantly attenuated the cardiomyocyte injury induced by Ang II (P < 0.05). The protein expression of phosphorylated p66shc in the whole cell lysates and total p66shc in the mitochondria increased in a dose-dependent manner when cardiomyocytes were exposed to Ang II (P < 0.05). Pretreatment with estrogen significantly down-regulated the protein expression of phosphorylated p66shc in the whole cell lysates and total p66shc in the mitochondria (P < 0.05). CONCLUSION: p66shc is involved in cardiomyocyte apoptosis induced by Ang II, and estrogen could attenuate Ang II induced cardiomyocyte injury through down-regulating the protein expression of p66shc.

Hydrogel microrobots for biomedical applications.

Recent years have witnessed a surge in the application of microrobots within the medical sector, with hydrogel microrobots standing out due to their distinctive advantages. These microrobots, characterized by their exceptional biocompatibility, adjustable physico-mechanical attributes, and acute sensitivity to biological environments, have emerged as pivotal tools in advancing medical applications such as targeted drug delivery, wound healing enhancement, bio-imaging, and precise surgical interventions. The capability of hydrogel microrobots to navigate and perform tasks within complex biological systems significantly enhances the precision, efficiency, and safety of therapeutic procedures. Firstly, this paper delves into the material classification and properties of hydrogel microrobots and compares the advantages of different hydrogel materials. Furthermore, it offers a comprehensive review of the principal categories and recent innovations in the synthesis, actuation mechanisms, and biomedical application of hydrogel-based microrobots. Finally, the manuscript identifies prevailing obstacles and future directions in hydrogel microrobot research, aiming to furnish insights that could propel advancements in this field.

Reservoir Characteristics and Formation Model of the Bauxite Gas Reservoir: The Benxi Formation in the LX Block, Northeast of Ordos Basin, China.

Recently, horizontal well L47-1CH in the Longdong area of the southwestern Ordos Basin made a significant breakthrough in bauxite natural gas exploration, changing the traditional geological understanding that bauxite could not form effective reservoirs. To further explore the exploration and development potential of bauxite natural gas reservoirs in the northeast of the Ordos Basin, it is urgent to carry out basic geological studies. This paper discusses the sedimentary environment, reservoir characteristics, and formation patterns of the bauxite gas reservoirs in the LX Block using trace elements, thin sections, X-ray diffraction, scanning electron microscopy, conventional physical properties, constant pressure mercury, etc. Then, the distribution pattern of bauxite was studied according to the restoration of the karst paleogeomorphology, and the formation model of bauxite was ultimately established. The results show that bauxite developed a clear triple-segment structure vertically, characterized by rich iron at the bottom, high aluminum at the middle, and low iron at the top. The mineral composition of the bauxite section mainly includes diaspore, iron minerals, titanium minerals, and birnessite. The types of pores mainly include intra- and intergranular dissolved pores, matrix-dissolved pores, intercrystalline pores, and microfractures. The porosity ranges from 1.51 to 9.90%, with a relatively good sorting and connectivity of the pore and throat. The bauxite was formed in a hot and humid climate, deposited in a shallow-water tidal flat and lagoon sedimentary environment with oxygen depleted, and experienced oscillatory regression during the deposition process. The thickness of bauxite is significantly controlled by karst paleogeomorphology, and it is mainly distributed at the negative terrain positions of karat pits and karst terraces. The above results can provide a geological basis for the exploration and development of bauxite in the Ordos Basin and similar basins worldwide.

A Mouth and Tongue Interactive Device to Control Wearable Robotic Limbs in Tasks where Human Limbs Are Occupied.

The Wearable Robotic Limb (WRL) is a type of robotic arm worn on the human body, aiming to enhance the wearer's operational capabilities. However, proposing additional methods to control and perceive the WRL when human limbs are heavily occupied with primary tasks presents a challenge. Existing interactive methods, such as voice, gaze, and electromyography (EMG), have limitations in control precision and convenience. To address this, we have developed an interactive device that utilizes the mouth and tongue. This device is lightweight and compact, allowing wearers to achieve continuous motion and contact force control of the WRL. By using a tongue controller and mouth gas pressure sensor, wearers can control the WRL while also receiving sensitive contact feedback through changes in mouth pressure. To facilitate bidirectional interaction between the wearer and the WRL, we have devised an algorithm that divides WRL control into motion and force-position hybrid modes. In order to evaluate the performance of the device, we conducted an experiment with ten participants tasked with completing a pin-hole assembly task with the assistance of the WRL system. The results show that the device enables continuous control of the position and contact force of the WRL, with users perceiving feedback through mouth airflow resistance. However, the experiment also revealed some shortcomings of the device, including user fatigue and its impact on breathing. After experimental investigation, it was observed that fatigue levels can decrease with training. Experimental studies have revealed that fatigue levels can decrease with training. Furthermore, the limitations of the device have shown potential for improvement through structural enhancements. Overall, our mouth and tongue interactive device shows promising potential in controlling the WRL during tasks where human limbs are occupied.

Magnetic-acoustic actuated spinous microrobot for enhanced degradation of organic pollutants.

A growing interest in the development of efficient strategies for the removal of organic pollutants from polluted water is emerging. As such, artificial micro/nano machines performing excellent water purification tasks have recently attracted more research attention of scientists. Hereby a spinous Fe3O4@PPy microrobot is presented that towards an efficient organic pollutant removal by enhancing Fenton-like reaction. The microrobot is fabricated by wrapping polypyrrole (PPy) on a spiny magnetic template prepared from sunflowers pollen. Modulating the sound pressure and frequency of the ultrasonic field enables the Fe3O4@PPy microrobot to present multimode motion, such as violent eruption-like motion caused by local cavitation (ELM), march-like unific motion (MLM), and typhoon-like rotation toward the center gathered motion (TLM). This multimode motion achieves the sufficient locomotion of microrobots in three-dimensional space and effective contact with organic pollutants in polluted water. Furthermore, a 5.2-fold increase in the degradation rate of methylene blue has been realized using Fe3O4@PPy microrobots under low-concentration hydrogen peroxide conditions. Also, the magnetically controlled recovery of microrobots from water after the completion of the degradation task has been demonstrated. The magnetic-acoustic actuated spinous microrobot can be extrapolated to other catalytic microrobot, developing a new strategy for an easier implementation and recovery of microrobot in real applications of water purification.

[Two-dimensional gel electrophoresis map of serum proteins in patients with chronic Keshan disease].

OBJECTIVE: To identify the different serum proteins expressed in patients with Keshan disease (KD). METHODS: Two-dimensional gel electrophoresis (2-DE) was performed with serum samples from the patients with chronic KD and healthy controls to separate serum proteins. The gels were stained by sliver and scanned by Umax scanner. The data were analyzed by ImageMaster 2D software. KD related proteins were identified through searching the ExPASy SWISS-2DPAGE database. RESULTS: Stable two-dimensional gel electrophoresis maps were established for serum samples of KD patients and healthy controls. A total of 808 and 814 protein spots were observed in KD patients and healthy controls, respectively. The two maps had 96.5475% identical protein spots and 44 differentially expressed protein spots. Eleven protein spots were expressed exclusively in KD patients and 12 protein spots only appeared in healthy controls. About 21 proteins were expressed in both groups but varied in quantities (14 proteins were over-expressed by more than 3 times and 7 proteins were under-expressed by more than 3 times in KD patients, P < 0.01). Among the 353 protein spots matched with the ExPASy-SWISS-2DPAGE databank, No. 1177 protein appeared in the KD patient was found to have the closest match with P02774 2-D0004T6 known as vitamin D binding protein (VDBP). CONCLUSION: There is a significant difference in serum protein expression between KD patients and normal people. VDBP might play a role in cardiac muscle damage via inflammatory immune reactions.

Symmetrical Efficient Gait Planning Based on Constrained Direct Collocation.

Biped locomotion provides more mobility and effectiveness compared with other methods. Animals have evolved efficient walking patterns that are pursued by biped robot researchers. Current researchers have observed that symmetry is a critical criterion to achieve efficient natural walking and usually realize symmetrical gait patterns through morphological characteristics using simplified dynamic models or artificial priors of the center of mass (CoM). However, few considerations of symmetry and energy consumption are introduced at the joint level, resulting in inefficient leg motion. In this paper, we propose a full-order biped gait planner in which the symmetry requirement, energy efficiency, and trajectory smoothness can all be involved at the joint level, and CoM motion is automatically determined without any morphological prior. In order to achieve a symmetrical and efficient walking pattern, we first investigated the characteristic of a completely symmetrical gait, and a group of nearly linear slacked constraints was designed for three phases of planning. Then a Constrained Direct Collocation (DIRCON)-based full-order biped gait planner with a weighted cost function for energy consumption and trajectory smoothness is proposed. A dynamic simulation with our newly designed robot model was performed in CoppliaSim to test the planner. Physical comparison experiments on a real robot device finally validated the symmetry characteristic and energy efficiency of the generated gait. In addition, a detailed presentation of the real biped robot is also provided.