Pharmacological inhibition of PI5P4Kα/ß disrupts cell energy metabolism and selectively kills p53-null tumor cells.

Most human cancer cells harbor loss-of-function mutations in the p53 tumor suppressor gene. Genetic experiments have shown that phosphatidylinositol 5-phosphate 4-kinase α and ß (PI5P4Kα and PI5P4Kß) are essential for the development of late-onset tumors in mice with germline p53 deletion, but the mechanism underlying this acquired dependence remains unclear. PI5P4K has been previously implicated in metabolic regulation. Here, we show that inhibition of PI5P4Kα/ß kinase activity by a potent and selective small-molecule probe disrupts cell energy homeostasis, causing AMPK activation and mTORC1 inhibition in a variety of cell types. Feedback through the S6K/insulin receptor substrate (IRS) loop contributes to insulin hypersensitivity and enhanced PI3K signaling in terminally differentiated myotubes. Most significantly, the energy stress induced by PI5P4Kαß inhibition is selectively toxic toward p53-null tumor cells. The chemical probe, and the structural basis for its exquisite specificity, provide a promising platform for further development, which may lead to a novel class of diabetes and cancer drugs.

Efficient fabrication of infrared antireflective microstructures on a curved Diamond-ZnS composite surface by using femtosecond Bessel-like beams.

Antireflective microstructures fabricated using femtosecond laser possess wide-ranging applicability and high stability across different spectral bands. However, due to the limited aspect ratio of the focused light field, traditional femtosecond laser manufacturing faces challenges in efficiently fabricating antireflective microstructures with high aspect ratio and small period, which are essential for antireflection, on curved surfaces. In this study, we present a robust and efficient method for fabricating high-aspect-ratio and basal surface insensitive antireflective microstructures using a spatially shaped Bessel-like beam. Based on theoretical simulation, a redesigned telescopic system is proposed to flexibly equalize the intensity of the Bessel beam along its propagation direction, facilitating the fabrication of antireflective subwavelength structures on the entire convex lens. The fabricated microstructures, featuring a width of less than 2 µm and a depth of 1 µm, enhance transmittance from 75% to 85% on Diamond-ZnS composite material (D-ZnS) surfaces. Our approach enables the creation of high aspect ratio subwavelength structures with a z-position difference exceeding 600 µm. This practical, efficient, and cost-effective method is facilitated for producing antireflective surfaces on aero-optical components utilized in aviation.

CT, MRI, and 18F-FDG PET/CT imaging features of seven cases of adult pancreatoblastoma.

OBJECTIVE: This study mainly analysed the imaging data for seven cases of adult pancreatoblastoma (PB) and summarized additional imaging features of this disease based on a literature review, aiming to improve the understanding and diagnosis rate of this disease. MATERIALS AND METHODS: The imaging data for seven adult patients pathologically diagnosed with adult PB were retrospectively analysed. Among the seven patients, six underwent computed tomography (CT) scans, two patients underwent abdominal magnetic resonance imaging (MRI), and five patients underwent 18F-FDG PET/CT. RESULTS: The tumours were located in the head of the pancreas in three cases, in the tail of the pancreas in two cases, and in the gastric antrum and neck of the pancreas in one case. Six tumours showed blurred edges, and an incomplete envelope was observed in only two cases when enhanced, which showed extruded growth and cyst-solid masses; one tumour was a solid mass with ossification. Showing mild or significant enhancement in the arterial phase (AP) for six cases. In the MRI sequence, isointensity was found on suppressed T1-weighted imaging, and hyperintensity was noted on suppressed T2-weighted imaging in two cases, with significant enhancement. Pancreatic duct dilatation was found in four cases. Tumour 18F-FDG PET/CT imaging exhibited high uptake in five cases. CONCLUSION: Adult PB involves a single tumour and commonly manifests as cystic-solid masses with blurred edges. Capsules are rare, ossification is an important feature, tumours can also present in ectopic pancreatic tissues, with mild or strengthening in the AP, and 18F-FDG uptake is high. These features are relatively specific characteristics in adult PB.

Comparison of the biometric parameters in patients with high myopia and anisometropia.

BACKGROUND: To compare biometric parameters, especially lens parameters, in patients with high myopia and anisometropia. METHODS: Patients with spherical equivalent greater than -6D and at least one eye with an axial length greater than 26 mm and a difference in binocular axial length greater than 2 mm were included in this study. In each patient, the eye with a relatively shorter axial length was assigned to Group S, and the other eye was assigned to Group L. In patients whose binocular axial length difference was greater than 4 mm, the eye with the shorter axial length was assigned to Group S1 and the other eye was assigned to Group L1. In patients whose shorter eye axial was less than 26 mm, the eye with the shorter axial was assigned to Group S2 and the other eye was assigned to Group L2. Central corneal thickness, corneal curvature radius, axial length, anterior chamber depth, lens thickness, white-to-white corneal diameter and the radius of the anterior and posterior lens capsules were compared between Group S and Group L, Groups S1 and L1, and Groups S2 and L2. RESULTS: Sixty-four people were enrolled in the study. There were 26 people with an axial length difference more than 4 mm (Group S1 and Group L1) and 34 patients with an axial length less than 26 mm (Group S2 and Group L2). No significant differences were found in any parameters except axial length between Group S and Group L, Groups S1 and L1, or Groups S2 and L2 (p > 0.05). CONCLUSIONS: The anterior parameters of patients with high myopia did not change with the axial length.

Gait variability following abrupt removal of external stabilization decreases with practice in incomplete spinal cord injury but increases in non-impaired individuals.

BACKGROUND: Individuals with incomplete spinal cord injury (iSCI) exhibit considerable lateral center of mass (COM) movement variability during gait transitions from a stabilizing to unassisted environment, while non-impaired individuals do not. To understand how iSCI influences gait adaption, we examined persons with and without iSCI performing repeated locomotor transitions. We hypothesized that, with practice, individuals with iSCI would prioritize COM control performance during the transition as exhibited by a reduction in kinematic variability. In, contrast, we hypothesized that non-impaired individuals would prioritize control effort by decreasing muscular activity. METHODS: Thirteen participants with iSCI and 12 non-impaired participants performed five treadmill-walking trials. During some trials, a cable-robot applied stabilizing lateral forces to the pelvis proportional in magnitude and opposite in direction to real-time lateral COM velocity. Each trial consisted of 300 continuous steps with or without a transition. During the first and last trials, no forces were applied and no transitions occurred (Null trials). During trials 2-4 (transition trials), the first 200 steps occurred in the stabilizing force field, forces were then abruptly removed, and 100 more unassisted steps were performed. We analyzed COM and step width variability, and hip abductor muscle activity during transitions (force removal until gait returned to steady state). RESULTS: Participants with iSCI displayed large COM movement variability during the first transition but reduced variability with practice. During the first transition, lateral COM speed, lateral COM excursion, and step width were all more variable than during the first Null trial (p < 0.05). By the third transition, no metric was different from Null trials (p > 0.05). In contrast, non-impaired participants' movement variability during the first transition was not different from Null trials (p > 0.05). With practice, movement variability increased: lateral COM excursion was more variable during Transitions 2 and 3 versus the first Null trial (p < 0.05). Non-impaired participants decreased hip abductor activity from Transition 1 to 3 (p < 0.05). CONCLUSIONS: Individuals with iSCI demonstrated rapid motor savings. By the third transition, individuals with iSCI reduced locomotor variability to baseline levels. In contrast, non-impaired participants prioritized control effort over control performance. With practice transitioning, non-impaired participants increased locomotor variability and decreased muscular effort.

Crocin Improves the Endothelial Function Regulated by Kca3.1 Through ERK and Akt Signaling Pathways.

BACKGROUND/AIMS: Based on the protective effect of crocin against cardiovascular diseases, we hypothesize that crocin could improve endothelial function through activating the eNOS(endothelial nitric oxide synthase) /NO pathway and/or the intermediate-conductance Ca2+-activated K+ channels (KCa3.1). METHODS: In this study, rat aortic rings were used to assess the regulatory effect of crocin on vascular tone and nitric oxide, prostacyclin, and KCa3.1, all endothelial vasodilators, were analyzed for effects by crocin. The expression profiles of p-eNOS, total-eNOS, p-ERK, total-ERK, p-Akt, total-Akt, KCa3.1, CD31, thrombomodulin, ICAM-1 and VCAM-1 were tested by western blotting. KCa3.1 was also analyzed by qPCR and immunofluorescence staining. Fluorescence and confocal microscopy were used to determine NO generation and intracellular Ca2+. Both EdU and MTT assays were used to evaluate cell viability. Cellular migration was assessed using transwell assay. RESULTS: Crocin relaxed pre-contracted artery rings through either NO or KCa3.1, but not PGI, in an endothelium-dependent manner. Furthermore, crocin increased p-eNOS, total-eNOS expression and NO production as well as intracellular Ca2+ in both HUVECs and HUAECs (Human Umbilical Artery Endothelial cells). Crocin also stimulated the expression of CD31, thrombomodulin and vascular cell adhesion molecule 1 (VCAM-1), as well as increased cellular proliferation and migration in vitro. Interestingly, we determined for the first time that by blocking or silencing KCa3.1 there was inhibition of crocin induced upregulation of p-eNOS and total-eNOS. Correspondingly, the KCa3.1 inhibitor TRAM-34 also reduced the expression of CD31, thrombomodulin and VCAM-1, as well as diminished intracellular Ca2+, cellular proliferation and migration. Finally, crocin stimulated the expression of p-ERK, total-ERK, p-Akt and total-Akt, however suppression of MEK and Akt inhibited this expression profile in endothelial cells. CONCLUSION: In the present study, these data strongly support the hypothesis that crocin could improve endothelial function through stimulation of the eNOS/NO pathway and other endothelial markers. This functional improvement is regulated by KCa3.1 via the MEK/ERK and PI3K/Akt signaling pathway.

Effects of nitrogen sources and metal ions on ethanol fermentation with cadmium-containing medium.

This study evaluated ethanol fermentation and its correlation with glutathione (GSH) synthesis under various cadmium-conditions with different metal ions and nitrogen sources. We found that corn steep liquor (CSL) and yeast extract have differential roles to play in GSH accumulation in cell even though both of them could alleviate the inhibition by cadmium. The different GSH accumulation in cell resulted from the different contents of metal ions in CSL and yeast extract. Intracellular GSH decreased with increasing calcium concentrations, and high calcium concentrations rendered the yeast more tolerant to cadmium stress than the nitrogen sources did. When the mole ratio of calcium to cadmium was 100:1, yeast tolerated 1000 µmol/L cadmium with no decrease in efficiency in ethanol production. As a result, the use of calcium allowed a significant saving of high-cost nutrient yeast extract with an efficient ethanol production, making the bioconversion of cadmium-containing biomass into ethanol possible.

Low-force human-human hand interactions induce gait changes through sensorimotor engagement instead of direct mechanical effects.

Physical human-robot interactions (pHRI) often provide mechanical force and power to aid walking without requiring voluntary effort from the human. Alternatively, principles of physical human-human interactions (pHHI) can inspire pHRI that aids walking by engaging human sensorimotor processes. We hypothesize that low-force pHHI can intuitively induce a person to alter their walking through haptic communication. In our experiment, an expert partner dancer influenced novice participants to alter step frequency solely through hand interactions. Without prior instruction, training, or knowledge of the expert's goal, novices decreased step frequency 29% and increased step frequency 18% based on low forces (< 20 N) at the hand. Power transfer at the hands was 3-700 × smaller than what is necessary to propel locomotion, suggesting that hand interactions did not mechanically constrain the novice's gait. Instead, the sign/direction of hand forces and power may communicate information about how to alter walking. Finally, the expert modulated her arm effective dynamics to match that of each novice, suggesting a bidirectional haptic communication strategy for pHRI that adapts to the human. Our results provide a framework for developing pHRI at the hand that may be applicable to assistive technology and physical rehabilitation, human-robot manufacturing, physical education, and recreation.

Self-Metallized Whole Cell Vaccines Prepared by Microfluidics for Bioorthogonally Catalyzed Antitumor Immunotherapy.

Tumor whole cell, carrying a complete set of tumor-associated antigens and tumor-specific antigens, has shown great potential in the construction of tumor vaccines but is hindered by the complex engineering means and limited efficacy to cause immunity. Herein, we provided a strategy for the self-mineralization of autologous tumor cells with palladium ions in microfluidic droplets, which endowed the engineered cells with both immune and catalytic functions, to establish a bioorthogonally catalytic tumor whole-cell vaccine. This vaccine showed strong inhibition both in the occurrence and recurrence of tumor by invoking the immediate antitumor immunity and building a long-term immunity.

Copper(II)-infused porphyrin MOF: maximum scavenging GSH for enhanced photodynamic disruption of bacterial biofilm.

Bacterial biofilm infection is a serious obstacle to clinical therapeutics. Photodynamic therapy (PDT) plays a dynamic role in combating biofilm infection by utilizing reactive oxygen species (ROS)-induced bacterial oxidation injury, showing advantages of mild side effects, spatiotemporal controllability and little drug resistance. However, superfluous glutathione (GSH) present in biofilm and bacteria corporately reduces ROS levels and seriously affects PDT efficiency. Herein, we have constructed a Cu2+-infused porphyrin metal-organic framework (MOF@Cu2+) for the enhanced photodynamic combating of biofilm infection by the maximum depletion of GSH. Our results show that the released Cu2+ from porphyrin MOF@Cu2+ could not only oxidize GSH in biofilm but also consume GSH leaked from ROS-destroyed bacteria, thus greatly weakening the antioxidant system in biofilm and bacteria and dramatically improving the ROS levels. As expected, our dual-enhanced PDT nanoplatform exhibits a strong biofilm eradication ability both in vitro and in an in vivo biofilm-infected mouse model. In addition, Cu2+ can promote biofilm-infected wound closing by provoking cell immigration, collagen sediment and angiogenesis. Besides, no apparent toxicity was detected after treatment with MOF@Cu2+. Overall, our design offers a new paradigm for photodynamic combating biofilm infection.

Microheater-Integrated Microlens Array for Robust Rapid Fog Removal.

In extreme environments, fog formation on a microlens array (MLA) surface results in a device failure. One reliable solution for fog removal is to heat the surface using a microheater. However, due to the surface interference, the combination of these two microdevices remains elusive. In this study, we introduce lift-off and electroless plating into femtosecond laser processing to fabricate a microheater integrated MLA (µH-MLA) on the same substrate with high light transmittance, durability, and fog removal efficiency. Laser-induced micro-nano grooves enable the microheater to be tightly coupled with the MLA and have high heating performance, thus maintaining a stable performance for over 24 h during continuous operation as well as under long time ultrasonic vibration and mechanical friction. With a rapid response time (τ0.5) of 17 s and a high working temperature of 188 °C, the µH-MLA removed fog that covers the entire face within 14 s. Finally, we prove the use of this fabrication method in large areas and curved surface environments. This study provides a flexible, stable, and economical method to integrate micro-optical and microelectrical devices.

Dual-Responsive Turn-On T1 Imaging-Guided Mild Photothermia for Precise Apoptotic Cancer Therapy.

Apoptosis has gained increasing attention in cancer therapy as an intrinsic signaling pathway, which leads to minimal leakage of waste products from a dying cell to neighboring normal cells. Among various stimuli to trigger apoptosis, mild hyperthermia is attractive but confronts limitations of non-specific heating and acquired resistance from elevated expression of heat shock proteins. Here, a dual-stimulation activated turn-on T1 imaging-based nanoparticulate system (DAS) is developed for mild photothermia (≈43 °C)-mediated precise apoptotic cancer therapy. In the DAS, a superparamagnetic quencher (ferroferric oxide nanoparticles, Fe3 O4 NPs) and a paramagnetic enhancer (Gd-DOTA complexes) are connected via the N6-methyladenine (m6 A)-caged, Zn2+ -dependent DNAzyme molecular device. The substrate strand of the DNAzyme contains one segment of Gd-DOTA complex-labeled sequence and another one of HSP70 antisense oligonucleotide. When the DAS is taken up by cancer cells, overexpressed fat mass and obesity-associated protein (FTO) specifically demethylates the m6 A group, thereby activating DNAzymes to cleave the substrate strand and simultaneously releasing Gd-DOTA complex-labeled oligonucleotides. The restored T1 signal from the liberated Gd-DOTA complexes lights up the tumor to guide the location and time of deploying 808 nm laser irradiation. Afterward, locally generated mild photothermia works in concert with HSP70 antisense oligonucleotides to promote apoptosis of tumor cells. This highly integrated design provides an alternative strategy for mild hyperthermia-mediated precise apoptotic cancer therapy.

Human-Human Hand Interactions Aid Balance During Walking by Haptic Communication.

Principles from human-human physical interaction may be necessary to design more intuitive and seamless robotic devices to aid human movement. Previous studies have shown that light touch can aid balance and that haptic communication can improve performance of physical tasks, but the effects of touch between two humans on walking balance has not been previously characterized. This study examines physical interaction between two persons when one person aids another in performing a beam-walking task. 12 pairs of healthy young adults held a force sensor with one hand while one person walked on a narrow balance beam (2 cm wide x 3.7 m long) and the other person walked overground by their side. We compare balance performance during partnered vs. solo beam-walking to examine the effects of haptic interaction, and we compare hand interaction mechanics during partnered beam-walking vs. overground walking to examine how the interaction aided balance. While holding the hand of a partner, participants were able to walk further on the beam without falling, reduce lateral sway, and decrease angular momentum in the frontal plane. We measured small hand force magnitudes (mean of 2.2 N laterally and 3.4 N vertically) that created opposing torque components about the beam axis and calculated the interaction torque, the overlapping opposing torque that does not contribute to motion of the beam-walker's body. We found higher interaction torque magnitudes during partnered beam-walking vs. partnered overground walking, and correlation between interaction torque magnitude and reductions in lateral sway. To gain insight into feasible controller designs to emulate human-human physical interactions for aiding walking balance, we modeled the relationship between each torque component and motion of the beam-walker's body as a mass-spring-damper system. Our model results show opposite types of mechanical elements (active vs. passive) for the two torque components. Our results demonstrate that hand interactions aid balance during partnered beam-walking by creating opposing torques that primarily serve haptic communication, and our model of the torques suggest control parameters for implementing human-human balance aid in human-robot interactions.

neurotic: Neuroscience Tool for Interactive Characterization.

A software tool for synchronization of video with signals would be of broad general use to behavioral neuroscientists. A new program, called neurotic (NEUROscience Tool for Interactive Characterization), allows users to review and annotate signal data synchronized with video, performs simple initial analyses including signal filtering and spike detection, is easy to use, and supports a variety of file formats. The program also facilitates collaborations by using a portable specification for loading and processing data and retrieving data files from online sources. Two examples are shown in which the software is used to explore experimental datasets with extracellular nerve or muscle recordings and simultaneous video of behavior. The configuration specification for controlling how data are located, loaded, processed, and plotted is also summarized. Algorithms for spike detection and burst detection are demonstrated. This new program could be used in many applications in which behavior and signals need to be analyzed together.

Speed impacts frontal-plane maneuver stability of individuals with incomplete spinal cord injury.

BACKGROUND: Following incomplete spinal cord injury, people often move slowly in an effort to maintain stability during walking maneuvers. Here we examine how maneuver speed impacts frontal-plane stability in people with incomplete spinal cord injury. We hypothesized that the challenge to control frontal-plane stability would increase with maneuver speed; specifically, the minimum lateral margin of stability would be smaller and the required coefficient of friction to avoid a slip would be greater during fast vs. preferred speed maneuvers. METHODS: We measured kinematics and ground reaction forces as 12 individuals with incomplete spinal cord injury performed side-step, lateral maneuvers at preferred and fast speeds. We examined four sequential steps: the Setup and Pushoff steps initiated the maneuver, and the Landing and Recovery steps arrested the maneuver. FINDINGS: Our hypotheses were partially supported. Maneuver time was shorter during fast vs. preferred speed maneuvers (p = 0.003). Minimum lateral margin of stability was smaller during the Setup step of fast vs. preferred speed maneuvers (p = 0.026). We found no differences in minimum lateral margin of stability between speeds for the Landing and Recovery steps (p > 0.05). The required coefficient of friction was not different between fast and preferred speed maneuvers (p = 0.087). INTERPRETATION: The greatest effect of increasing maneuver speed occurred during the Setup step; as speed increased, participants reduced their minimum lateral margin of stability ipsilateral to the maneuver direction. This action allowed maneuvers to be performed more quickly without requiring a greater lateral impulse during the Pushoff step. However, this strategy reduced passive stability.

Walking With Ears: Altered Auditory Feedback Impacts Gait Step Length in Older Adults.

Auditory feedback may provide the nervous system with valuable temporal (e. g., footstep sounds) and spatial (e.g., external reference sounds) information that can assist in the control of upright walking. As such, hearing loss may directly contribute to declines in mobility among older adults. Our purpose was to examine the impact of auditory feedback on the control of walking in older adults. Twenty older adults (65-86 years) with no diagnosed hearing loss walked on a treadmill for three sound conditions: Baseline, Ear Plugs, and White Noise. We hypothesized that in response to reduced temporal auditory feedback during the Ear Plugs and White Noise conditions, participants would adapt shorter and faster steps that are traditionally believed to increase mechanical stability. This hypothesis was not supported. Interestingly, we observed increases in step length (p = 0.047) and step time (p = 0.026) during the Ear Plugs condition vs. Baseline. Taking longer steps during the Ear Plugs condition may have increased ground reaction forces, thus allowing participants to sense footsteps via an occlusion effect. As a follow-up, we performed a Pearson's correlation relating the step length increase during the Ear Plugs condition to participants' scores on a clinical walking balance test, the Functional Gait Assessment. We found a moderate negative relationship (rho = -0.44, p = 0.055), indicating that participants with worse balance made the greatest increases in step length during the Ear Plugs condition. This trend suggests that participants may have actively sought auditory feedback with longer steps, sacrificing a more mechanically stable stepping pattern. We also hypothesized that reduced spatial localization feedback during the Ear Plugs and White Noise conditions would decrease control of center of mass (COM) dynamics, resulting in an increase in lateral COM excursion, lateral margin of stability, and maximum Lyapunov exponent. However, we found no main effects of auditory feedback on these metrics (p = 0.580, p = 0.896, and p = 0.056, respectively). Overall, these results suggest that during a steady-state walking task, healthy older adults can maintain walking control without auditory feedback. However, increases in step length observed during the Ear Plugs condition suggest that temporal auditory cues provide locomotor feedback that becomes increasingly valuable as balance deteriorates with age.

A novel Movement Amplification environment reveals effects of controlling lateral centre of mass motion on gait stability and metabolic cost.

During human walking, the centre of mass (COM) laterally oscillates, regularly transitioning its position above the two alternating support limbs. To maintain upright forward-directed walking, lateral COM excursion should remain within the base of support, on average. As necessary, humans can modify COM motion through various methods, including foot placement. How the nervous system controls these oscillations and the costs associated with control are not fully understood. To examine how lateral COM motions are controlled, healthy participants walked in a 'Movement Amplification' force field that increased lateral COM momentum in a manner dependent on the participant's own motion (forces were applied to the pelvis proportional to and in the same direction as lateral COM velocity). We hypothesized that metabolic cost to control lateral COM motion would increase with the gain of the field. In the Movement Amplification field, participants were significantly less stable than during baseline walking. Stability significantly decreased as the field gain increased. Participants also modified gait patterns, including increasing step width, which increased the metabolic cost of transport as the field gain increased. These results support previous research suggesting that humans modulate foot placement to control lateral COM motion, incurring a metabolic cost.

American Society of Biomechanics Journal of Biomechanics Award 2018: Adaptive motor planning of center-of-mass trajectory during goal-directed walking in novel environments.

To aid in the successful execution of goal-directed walking (discrete movement from a start location to an end target) the central nervous system forms a predictive motor plan. For the motor plan to be effective, it must be adapted in response to environmental changes. Despite motor planning being inherent to goal-directed walking, it is not understood how the nervous system adapts these plans to interact with changing environments. Our objective was to understand how people adapt motor plans of center of mass (COM) trajectory during goal-directed walking in response to a consistent change in environmental dynamics. Participants preformed a series of goal-directed walking trials in a novel environment created by a cable robot that applied a lateral force field to their COM. We hypothesized that participants would adapt to the environment by forming an internal model of their COM trajectory within the force field. Our findings support this hypothesis. Initially, we found COM trajectory significantly deviated in the same direction as the applied field, relative to baseline (no field) (p = 0.002). However, with practice in the field, COM trajectory adapted back to the baseline (p = 0.6). When we unexpectedly removed the field, participants demonstrated after-effects, COM trajectory deviated in the direction opposite of the field relative to baseline (p < 0.001). Our findings suggest that when performing a goal-directed walking task, people adapt a motor plan that predicts the COM trajectory that will emerge from the interaction between a specific set of motor commands and the external environment.

Simultaneous Enhancement of the Thermoelectric and Mechanical Performance in One-Step Sintered n-Type Bi2Te3-Based Alloys via a Facile MgB2 Doping Strategy.

The Bi2Te3-based alloys have been commercialized for the applications of energy harvesting and refrigeration for decades. However, the commercial Bi2Te3-based alloys produced by the zone-melting (ZM) method usually show poor mechanical strength and crack problems as well as the sluggish figure of merit ZT, especially for the less-progressed n-type samples. In this work, we have simultaneously enhanced the thermoelectric and mechanical performance of the one-step spark plasma sintering (SPS)-derived n-type Bi2Te2.7Se0.3 alloys just by doping a small amount of superconducting material MgB2 where Mg and B atoms can play significant roles in carrier density optimization and hardness enhancement. Besides the optimization of carrier density, the MgB2 doping can also increase the carrier mobility but decrease the lattice and bipolar thermal conductivity, leading to a peak ZT of 0.96 at 325 K and an average ZT of 0.88 within 300-500 K in the 0.5% MgB2-doped Bi2Te2.7Se0.3 (BTSMB) alloys. The peak ZT and average ZT of our optimized BTSMB samples are comparable and higher than those of the state-of-the-art commercial ZM ingot. Moreover, the optimized BTSMB sample also exhibits almost 70% enhancement in hardness compared with the ZM ingot. Our results demonstrate the great potential of the MgB2 doping strategy for mass production of SPS-derived Bi2Te3-based alloys in one-step sintering.