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Lithium and exercise ameliorate insulin-deficient hyperglycemia by independently attenuating pancreatic α-cell mass and hepatic gluconeogenesis
Get PDFAs in type 1 diabetes, the loss of pancreatic β-cells leads to insulin deficiency and the subsequent development of hyperglycemia. Exercise has been proposed as a viable remedy for hyperglycemia. Lithium, which has been used as a treatment for bipolar disorder, has also been shown to improve glucose homeostasis under the conditions of obesity and type 2 diabetes by enhancing the effects of exercise on the skeletal muscles. In this study, we demonstrated that unlike in obesity and type 2 diabetic conditions, under the condition of insulin-deficient type 1 diabetes, lithium administration attenuated pancreatic a-cell mass without altering insulin-secreting β-cell mass, implying a selective impact on glucagon production. Additionally, we also documented that lithium downregulated the hepatic gluconeogenic program by decreasing G6Pase protein levels and upregulating AMPK activity. These findings suggest that lithium’s effect on glucose metabolism in type 1 diabetes is mediated through a different mechanism than those associated with exerciseinduced metabolic changes in the muscle. Therefore, our research presents the novel therapeutic potential of lithium in the treatment of type 1 diabetes, which can be utilized along with insulin and independently of exercise. © Korean Journal of Physiology & PharmacologyTRU
Challenges and Advances in High-Energy Magnesium Batteries
No full textDespite the widespread use of Li-ion batteries, their limited energy density poses a significant challenge. Magnesium (Mg) batteries present a promising alternative due to their higher energy density and lower cost. However, existing Mg battery technologies encounter obstacles, particularly regarding electrode-electrolyte compatibility. The initial Mg battery prototype, employing the Mg/Mo6S8 system, exhibited a mere ~60 Wh/kgcell, significantly lower than Li-ion batteries (~300 Wh/kgcell). Despite efforts over the past two decades to develop new cathodes, electrolytes, and Mg anodes, most reported Mg battery systems have struggled with low energy densities and reproducibility issues.
In this presentation, we highlight recent breakthroughs in Mg batteries, achieving energy densities comparable to Li-ion batteries. Our approach incorporates novel cathode materials developed in our research group, surface-modified Mg anodes, and conventional nonaqueous electrolytes. Through our work, we aim to shed light on the development of advanced Mg battery systems capable of surpassing the energy density limitations of Li-ion batteries while maintaining cost-effectiveness
Efficient Forward-Only Training for Brain-Inspired Hyperdimensional Computing
No full textHyperdimensional (HD) computing is an emerging paradigm inspired by human cognition, utilizing high-dimensional vectors to represent and learn information in a lightweight manner based on its simple and efficient operations. In HD-based learning frameworks, the encoding of the high dimensional representations is the most contributing procedure to accuracy and efficiency. However, throughout HD computing's history, the encoder has largely remained static, which leads to sub-optimal hypervector representations and excessive dimensionality requirements. In this paper, we propose novel forward-only training methods for HD encoders, Stochastic Error Projection (SEP) and Input Modulated Projection (IMP), which dynamically adjust the encoding process during training. Our methods achieve accuracies comparable to state-of-the-art HD-based techniques, with SEP and IMP outperforming existing methods by 5.49% on average at a reduced dimensionality of D = 3,000. This reduction in dimensionality results in a 3.32x faster inference. © 2024 IEEE
Modular System Design for Real-time Communication and Data Integration in Microbial Metabolite Detection
No full text본 연구는 실내 공기 중 미생물 대사물질을 실시간으로 검출하고 분석하는 시스템을 개발하는 데 초점을 맞추고 있다. 미생물 대사물질을 감지하는 센서 기술이 아직 연구실 단계에 머물러 있어, 현장 적용을 위한 임시 방편으로 장비 구동 프로그램, 센서 구동 프로그램, 데이터 처리 및 분석 프로그램 간의 통신 구조를 설계하였다. 이 시스템은 MQTT 프로토콜을 사용하여 프로그램 간의 데이터를 실시간으로 주고받으며, 장비 구동 프로그램의 단계에 따라 센서 데이터를 분석하고, 결과를 HTTP API를 통해 서버로 전송하는 구조를 가진다. 연구 결과, 각 프로그램 간의 MQTT 기반 통신은 실시간 데이터 전송의 안정성을 보장하였으며, 센싱 준비 단계에서만 데이터를 분석하는 방식으로 데이터 처리 효율성을 극대화하였다. 본 시스템은 1시간 주기로 공기를 포집하고, 5분마다 센서 데이터를 전송하여 실시간 모니터링과 분석을 성공적으로 수행하였다. 또한, 통신 구조의 유연성은 향후 센서 모듈화 및 상용화가 이루어질 때 손쉽게 확장 가능함을 입증하였다
The Cobalt Thickness Dependent Magnetic Properties of Pt/Co/Pt Thin Films
No full text본 연구에서는 브릴루앙 광 산란(Brillouin light scattering) 실험을 이용하여 Co 박막의 두께변화에 대한 자화 동역학의 특성에 관한 연구를 수행하였다. 다양한 두께의 Co 박막을 DC 마그네트론 스퍼터를 이용하여 제작하였다. 외부 자기장의 변화에 따른 스핀파의 주파수를 측정하여 Co 박막의 포화자화, 수직자기 이방성 에너지 등의 자성특성에 대하여 연구를 수행하였다. 결정된 포화자화와 표면 수직자기 이방성 에너지 밀도는 각각 994 ± 30 kA/m, 0.73 ± 0.01 mJ/m2이다. 또한 Co 박막의 두께변화에따른 스핀파 주파수를 측정하고, 계산 값과 비교하였다. 측정된 스핀파의 주파수와 자성박막의 경계조건에 의하여 계산된 스핀파의 주파수를 비교한 결과, 약 5 nm 정도까지의 스핀파는 수직자기 이방성 에너지만을 고려해도 되지만, 수직자기 이방성 에너지가 포함된 5 mn 이상의 자성박막의 스핀파에 대한 연구는 경계조건에 따라서 조심스러운 접근이 필요하다.
We investigate various magnetic properties of cobalt thin films with varying thicknesses by performing Brillouin light scattering spectroscopy. The thickness of the are deposited by using DC the magnetron sputtering system. By measuring the frequency of the propagating spin waves under different external magnetic fields, we analyze the magnetic characteristics of the Co thin films, such as the saturation magnetization and the perpendicular magnetic anisotropy energy. The determined saturation magnetization and surface perpendicular magnetic anisotropy energy density are approximately 994 ± 30 ㎄/m and 0.73 ± 0.01 mJ/㎡, respectively. Additionally, we measure the spin wave frequencies for various cobalt film thicknesses and it is directly compared with the analytically calculated values. Comparing the measured spin wave frequencies with analytically calculated spinwave frequencies, it is found that for spin waves in magnetic films up to approximately 5 ㎚ thick, considering only the perpendicular magnetic anisotropy energy is sufficient. However, for spin waves in magnetic thin films thicker than 5 ㎚, which include perpendicular magnetic anisotropy energy, a careful approach is required depending on the boundary conditions such as exchange and dipole interactions.FALSEkc
Flexible endoscope manipulating robot using quad-roller friction mechanism
Get PDFA robotic system for manipulating a flexible endoscope in surgery can provide enhanced accuracy and usability compared to manual operation. However, previous studies require large-scale, complex hardware systems to implement the rotational and translational motions of the soft endoscope cable. The conventional control of the endoscope by actuating the endoscope handle also leads to undesired slack between the endoscope tip and the handle, which becomes more problematic with long endoscopes such as a colonoscope. This study proposes a compact quad-roller friction mechanism that enables rotational and translational motions triggered not from the endoscope handle but at the endoscope tip. Controlling two pairs of tilted rollers achieves both types of motion within a small space. The proposed system also introduces an unsynchronized motion strategy between the handle and tip parts to minimize the robot’s motion near the patient by employing the slack positively as a control index. Experiments indicate that the proposed system achieves accurate rotational and translational motions, and the unsynchronized control method reduces the total translational motion by up to 88% compared to the previous method. © 2024 The Author(s). Published by Informa UK Limited, trading as Taylor & Francis Group.TRUEsciescopu
CONTINUOUS TIME DELTA-SIGMA ADC AND OPERATING METHOD THEREOF
No full text본 발명은 연속시간 델타 시그마 아날로그-디지털 변환 장치 및 그 동작 방법에 관한 것으로, 일실시예에 따른 연속시간 델타 시그마 아날로그-디지털 변환 장치는 기 설정된 입력 전압을 수신하는 선형 트랜스컨덕턴스 회로(linear Gm circuit)의 동작에 기초하여 입력 전압에 대응되는 제1 출력 신호를 생성하는 선형 적분기 및 제1 출력 신호를 수신하는 바디 구동 오실레이터(body-driven VCO)의 동작에 기초하여 제1 출력 신호에 대응되는 제2 출력 신호를 생성하고, 제2 출력 신호를 수신하는 FDC(frequency to digital converter)의 동작에 기초하여 제2 출력 신호에 대응되는 디지털 출력 코드를 생성하는 양자화기를 포함한다
Preliminary Modeling of Energy-Aware Integrated Allocations in Robotic Mobile Fulfillment Systems
No full textThe Robotic Mobile Fulfillment System (RMFS) is an automated technology to fulfill various types of orders (e.g., vehicle assembly) in modern warehouses or factories. In particular, battery-equipped mobile robots move racks that contain various components (Stock Keeping Unit) by visiting replenishment or picking stations to complete orders. We formulate the preliminary system model to optimize the order throughput and energy consumption of mobile robots, which consists of (i) rack allocation, (ii) task allocation, and (iii) route routing. © 2024 IEEE
PDMS-based Magnetic Mechanical Sensors for Healthcare Devices - Design, Modeling & Integration
No full textMechanical sensor, pressure sensor, magnetic sensor, 3D printing, polydimethylsiloxaneWithin the realm of flexible and wearable electronics, mechanical sensors such as pressure sensors are among the most highly researched devices for both industrial and academia purposes, primarily due to their ease of operation and their broad range of usage. In the healthcare sector for instance, various wearable and portable mechanical sensors have found their way into diagnostic and monitoring devices, allowing patients to integrate these devices into their everyday lives with ease. In an effort to improve wearable devices for this particular application, this thesis introduces two versions of pressure sensor for various biomedical applications, including respiration measurement and pulse monitoring. To differentiate it from conventional, established sensor systems, the devices in this work utilize a magnetic sensor and simple 3D printing methodology. The elastomer polydimethylsiloxane (PDMS) was chosen to be one of the most essential elements and was thus studied in advance for finite element method (FEM) modeling. Detailed investigation on PDMS using FEM as well as creative structural design of the sensor played major parts in optimizing the sensors performance which were then demonstrated in actual healthcare monitoring processes. Keywords: Mechanical sensor, pressure sensor, magnetic sensor, 3D printing, polydimethylsiloxane|압력 센서와 같은 기계적 센서는 조작이 용이하고 광범위한 사용 범위를 가져, 유연하고 착용할 수 있는 디바이스로 산업 및 학계에서 많이 연구되고 있는 디바이스 중 하나이다. 예를 들어 의료 분야에서는 다양한 휴대용 웨어러블 기계식 센서가 진단 및 모니터링 장치로서 환자가 일상생활에 쉽게 사용할 수 있게 되었다. 본 논문에서는 이와 같은 웨어러블 디바이스에 적용하기 위한 방법으로, 호흡 측정과 맥박 모니터링과 같은 생체 신호의 측정이 가능한 바이오 메디컬 압력센서를 두 가지 형태로 시연하였다. 기존의 센서 시스템과 차별화하기 위해 자기 센서와 간단한 3D 프린팅 방법을 사용하였다. 탄성 폴리 디메틸실록산(polydimethylsiloxane; PDMS)는 디바이스의 핵심 재료 중 하나로 선택되었으며 유한 요소 방법 모델(FEM)을 통해 디바이스의 최적화된 형태가 모델링 되었다. FEM을 이용한 PDMS에 대한 심층 분석과 센서의 독창적인 구조 설계는 센서 성능의 최적화에 중요한 역할을 하였으며, 이는 실제 의료 모니터링 과정에서 입증되었다.
핵심어: 기계식 센서, 압력 센서, 자기 센서, 3D 프린팅, 폴리디메틸실록산Abstract i
List of contents iii
List of tables vi
List of figures vii
Ⅰ. Introduction
1.1 Wearable devices in the biomedical field 1
1.2 Mechanical sensors 1
1.2.1 Pressure sensors 2
1.3 Magnetic sensors 3
1.4 Sensor materials 5
1.4.1 Polylactic acid (PLA) 5
1.4.2 Polydimethylsiloxane (PDMS) 8
1.5 Sensor design 10
1.5.1 Implementation of microstructured surfaces 10
1.5.2 Multifunctionality from design detachability 12
1.6 Finite element method (FEM) 14
1.6.1 Structural analysis through simulation 14
1.6.2 Material modeling 15
IⅠ. Theoretical & Mathematical Development
2.1 Modeling of hyperelastic materials 17
2.1.1 Neo-Hookean model 19
2.1.2 Mooney-Rivlin 2 parameter model 19
2.1.3 Mooney-Rivlin 5 parameter model 19
2.1.4 Ogden model 20
2.1.5 Yeoh model 20
ⅠII. Experimental Methods & Materials
3.1 Magnetic sensor 21
3.1.1 Fabrication 21
3.1.2 Characterization 23
3.2 Polylactic acid (PLA) 26
3.2.1 Fabrication 26
3.3 Polydimethylsiloxane (PDMS) 27
3.3.1 Fabrication 28
3.3.1.1 For FEM 28
3.3.1.2 For the pressure sensor 31
3.3.1.3 For the respiration sensor 32
3.3.2 Characterization 33
3.3.2.1 For FEM 33
3.3.2.2 For the pressure sensor 35
3.3.2.3 For the respiration sensor 37
3.4 Finite element method (FEM) 38
3.4.1 COMSOL optimization module 38
3.4.2 COMSOL structural mechanics module 39
IV. Results & Discussion
4.1 Modeling of PDMS 41
4.1.1 Selection of material models 41
4.1.2 FEM simulations 48
4.1.3 Effects of combining different mechanical experiments 51
4.1.4 Varying the base to curing agent blend of PDMS samples 55
4.1.4 Experimental validation 57
4.2 Pressure Sensor 59
4.2.1 Conceptual design 59
4.2.2 Performance of the generic pressure sensor (mechanical loading) 62
4.2.3 Performance of the respiration sensor (air pressure loading) 68
4.2.4 FEA of microstructured PDMS layers 72
4.2.5 Health monitoring applications 78
V. Conclusion 91
Appendix 94
References 95DoctordCollectio
The ICL1 and MLS1 Genes, Integral to the Glyoxylate Cycle, are Essential and Specific for Caloric Restriction-Mediated Extension of Lifespan in Budding Yeast
Get PDFThe regulation of complex energy metabolism is intricately linked to cellular energy demands. Caloric restriction (CR) plays a pivotal role in modulating the expression of genes associated with key metabolic pathways, including glycolysis, the tricarboxylic acid (TCA) cycle, and the glyoxylate cycle. In this study, the chronological lifespan (CLS) of 35 viable single-gene deletion mutants under both non-restricted and CR conditions, focusing on genes related to these metabolic pathways is evaluated. CR is found to increase CLS predominantly in mutants associated with the glycolysis and TCA cycle. However, this beneficial effect of CR is not observed in mutants of the glyoxylate cycle, particularly those lacking genes for critical enzymes like isocitrate lyase 1 (icl1Δ) and malate synthase 1 (mls1Δ). This analysis revealed an increase in isocitrate lyase activity, a key enzyme of the glyoxylate cycle, under CR, unlike the activity of isocitrate dehydrogenase, which remains unchanged and is specific to the TCA cycle. Interestingly, rapamycin, a compound known for extending lifespan, does not increase the activity of the glyoxylate cycle enzyme. This suggests that CR affects lifespan through a distinct metabolic mechanism. © 2024 The Authors. Advanced Biology published by Wiley-VCH GmbH.TRUEsciescopu