A Study on Statistical Reliability Analyses in Silicon Oxide and Magnesium Oxide Films due to Localized Defects

要約のみTohoku University須川成利課

Recent advances in label-free imaging and quantification techniques for the study of lipid droplets in cells

Lipid droplets (LDs), once considered mere storage depots for lipids, have gained recognition for their intricate roles in cellular processes, including metabolism, membrane trafficking, and disease states like obesity and cancer. This review explores label-free imaging techniques' applications in LD research. We discuss holotomography and vibrational spectroscopic microscopy, emphasizing their potential for studying LDs without molecular labels, and we highlight the growing integration of artificial intelligence. Clinical applications in disease diagnosis and therapy are also considered

Optical manipulation of a dielectric particle along polygonal closed-loop geometries within a single water droplet

This work was supported by the National Research Foundation of Korea (NRF) Grant funded by the Korea government (MSIT) (No. 2019R1A2C2011293) and the UK Engineering and Physical Sciences Research Council (Grant EP/P030017/1).We report a new method to optically manipulate a single dielectric particle along closed-loop polygonal trajectories by crossing a suite of all-fiber Bessel-like beams within a single water droplet. Exploiting optical radiation pressure, this method demonstrates the circulation of a single polystyrene bead in both a triangular and a rectangle geometry enabling the trapped particle to undergo multiple circulations successfully. The crossing of the Bessel-like beams creates polygonal corners where the trapped particles successfully make abrupt turns with acute angles, which is a novel capability in microfluidics. This offers an optofluidic paradigm for particle transport overcoming turbulences in conventional microfluidic chips.Publisher PDFPeer reviewe

INO80 function is required for mouse mammary gland development, but mutation alone may be insufficient for breast cancer

The aberrant function of ATP-dependent chromatin remodeler INO80 has been implicated in multiple types of cancers by altering chromatin architecture and gene expression; however, the underlying mechanism of the functional involvement of INO80 mutation in cancer etiology, especially in breast cancer, remains unclear. In the present study, we have performed a weighted gene co-expression network analysis (WCGNA) to investigate links between INO80 expression and breast cancer sub-classification and progression. Our analysis revealed that INO80 repression is associated with differential responsiveness of estrogen receptors (ERs) depending upon breast cancer subtype, ER networks, and increased risk of breast carcinogenesis. To determine whether INO80 loss induces breast tumors, a conditional INO80-knockout (INO80 cKO) mouse model was generated using the Cre-loxP system. Phenotypic characterization revealed that INO80 cKO led to reduced branching and length of the mammary ducts at all stages. However, the INO80 cKO mouse model had unaltered lumen morphology and failed to spontaneously induce tumorigenesis in mammary gland tissue. Therefore, our study suggests that the aberrant function of INO80 is potentially associated with breast cancer by modulating gene expression. INO80 mutation alone is insufficient for breast tumorigenesis

Magnetically steerable manipulator with variable stiffness using graphene polylactic acid for minimally invasive surgery

For manipulators used in minimally invasive surgery (MIS), variable stiffness and miniaturization are very important characteristics. However, previously proposed mechanisms are difficult to miniaturize due to large and complex structures; thus, they do not achieve variable stiffness characteristics, consequently being difficult to be applied to manipulators used in MIS. In this study, we proposed a manipulator that can be magnetically steered by a permanent magnet at the end and can have variable stiffness characteristics by a phase transition of graphene polylactic acid (GPLA). Thus, the proposed manipulator is easy to fabricate and miniaturize as a magnetic steering MIS manipulator. To verify the magnetic steering and variable stiffness performances of the proposed manipulator, various basic experiments and analysis simulations were executed. In addition, by applying the discriminating properties of the proposed manipulator (magnetic steering, variable stiffness), we can construct a double-segment manipulator with variable stiffness and verify its implementation in postures which are difficult to achieve in other MIS manipulators. © 2020 Elsevier B.V.1

Optimized Halbach array for focused magnetic drug targeting

Magnetic drug targeting (MDT) is a therapeutic method that delivers drug carriers containing magnetic nanoparticles to a target lesion by directing them using an external magnetic field. To minimize the possible side effects on the surrounding normal cells, focused magnetic drug targeting (FMDT) has been introduced, which allows drug carriers to be delivered only to the target lesions. FMDT, with its capability for local focusing and wide attraction, aims for highly efficient and concentrated drug delivery. In this study, a modified quasi-axisymmetric Halbach array design was introduced as an external magnetic source to perform FMDT. The proposed Halbach array design has a simple structure that is easy to assemble, unlike earlier Halbach array designs. The optimized Halbach array is fabricated as a result of the optimization of the magnetic force magnitude and local focusing with wide attraction using finite element method (FEM) analysis. Through simulations and experiments, the optimized Halbach array design is validated and a comparative analysis with other magnet types is performed. As a result, the optimization of the Halbach array using FEM is experimentally validated, and it is confirmed that the optimized Halbach array is more effective for FMDT than the permanent magnet used in MDT. © 2020 Elsevier B.V.1

Analysis of drivable area and magnetic force in quadrupole electromagnetic actuation system with movable cores

Recently, significant attention has been paid to the development of electromagnetically actuated microrobots. Various types of electromagnetic actuation (EMA) systems have been proposed and put into practice. Owing to their limited workspace and driving force, the previous EMA systems were used restrictively in microrobots of specific sizes. Arguably, more research should be conducted on driving microrobots of various sizes using a single EMA system. In this study, a novel quadrupole EMA system with movable magnetic cores is proposed for driving microrobots of various sizes. Sharp magnetic cores and a closed magnetic circuit method are introduced to generate a magnetic field of high intensity and gradient with a small current. In addition, an analytical definition of the drivable area (DA) is presented in which a microrobot can move to the desired direction. The DA is estimated using a finite element method (FEM) and is verified via experimental results. The effectiveness of the proposed EMA system is verified by analyzing the changes in DA and magnetic force according to variations in the positions of the magnetic core. The results imply that driving microrobots of various sizes is possible. Moreover, it is shown that an EMA system with movable cores could be manipulated more efficiently than those with fixed cores. © 2020 Elsevier Ltd1

Reprogrammable Magnetically Actuated Self‐Assembled Cilia Array

Motile cilia move in an asymmetric pattern and implement a metachronal wave (MCW) to facilitate fluid movement in a viscous environment. Studies have been conducted to mimic MCW movement of motile cilia, but the fabrication process is too complicating or there are difficulties in accurately mimicking the shape of the cilia. To overcome these limitations, a self‐assembly method is introduced to fabricate a reprogrammable magnetically actuated self‐assembled (RMS) cilia array that can be reprogrammed by changing the magnetization direction through additional magnetization. Using the RMS cilia array, a unilateral cilia array (UCA) channel and a bilateral cilia array (BCA) channel are constructed, and the motion and fluid flow of the RMS cilia array are analyzed by applying different magnetic fields (strike magnetic field and rotating magnetic field). When a rotating magnetic field is applied to the UCA channel, a distinct MCW appears. In the BCA channel test, fluid pumping is observed when a strike magnetic field is applied, whereas fluid mixing is observed when a rotating magnetic field is applied. Based on these results, it is expected that the proposed RMS cilia array and magnetic field actuation can be applied to lab‐on‐a‐chip or microfluidic channels for fluid mixing and pumping

pH Sensor-Embedded Magnetically Driven Capsule for H. pylori Infection Diagnosis

The Campylobacter-like organism (CLO) test is the most commonly employed test for diagnosing Helicobacter pylori (H. pylori) infection in the stomach. Since the CLO test is an invasive method, non-invasive methods have been proposed. However, the proposed methods exhibit relatively low specificity and sensitivity. In this letter, a novel H. pylori infection diagnosis method that uses a pH sensor-embedded magnetically driven capsule is proposed. The proposed method adopts the principle of the CLO test to diagnose H. pylori infection non-invasively. The capsule comprises two chambers to sample gastric juice, and a pH sensor is embedded inside each chamber. Therefore, H. pylori infection can be diagnosed using the urea hydrolysis property of H. pylori and a pH sensor embedded in the chambers of the capsule. In addition, the capsule can be magnetically actuated using an external magnetic field owing to its neodymium-magnet. The performance of the proposed capsule was evaluated in several aspects. First, the sensing ability of the fabricated pH sensor was verified using a pH buffer solution. Second, the magnetic actuation capacity of the capsule was evaluated using a 6-coil electromagnetic actuation (EMA) system. Third, the gastric juice sampling and pH-sensing capabilities of the assembled capsule were evaluated using a phantom test. Finally, the ability to diagnose H. pylori infection was validated using an ex vivo test. Consequently, this letter highlights the potential feasibility of establishing an H. pylori infection diagnosis method using a pH sensor-embedded magnetically driven capsule