An elastic deformation model of high speed spindles built into ball bearings

Kinematic characteristics and elastic deformation properties of ball bearings such as stiffness, axial, and radial deflections of the rings, speeds of balls, contact angles, and loads, all vary strongly with rotational speed, temperature, and axial preload. This paper presents an elastic deformation model of spindle units built into ball bearings, which are running on high rotational speed and axial preload. For this, software for simulation of the high speed spindle units was developed and introduced into a practical use. A computer aided analysis of the model was carried out and experiments were made, which showed a significant effect of high rotational speed, cutting load, bearing axial preload, and a new effect for which the criteria for a choice of bearing preload are given.     

Wafer size effect on material removal rate in copper CMP process

Journal of Mechanical Science and Technology - The semiconductor industry has employed the Chemical mechanical planarization (CMP) to enable surface topography control. Copper has been used to...     

Artificial Immunogenic Cell Death Lipid Nanoparticle Functions as a Therapeutic Vaccine for Cancer

Anticancer drug-mediated induction of immunogenic cell death (ICD) blocks metastasis or recurrence in cancer cells by promoting specific immune activity against cancer antigens. However, this strategy has failed to afford adequate treatment efficiency. Overcoming the failure of ICD-mediated cancer therapy, lipid nanoparticles (LNPs) containing cancer cell surface proteins are synthesized using sonication and extrusion without microfluidics. In addition, these LNPs are decorated with high-mobility group box 1 protein and calreticulin, indicators of ICD, and named artificial ICD LNPs (AiLNPs). Administration of AiLNPs effectively targets dendritic cells (DCs) and induces DC activation in mice. Moreover, treating CT-26 tumor-bearing mice with AiLNPs inhibits tumor growth by inducing CT-26 antigen-specific T-cell immunity. Furthermore, AiLNPs containing Lewis lung carcinoma (LLC1) membrane proteins can prevent metastatic LLC1 tumor growth in the lung via LLC1 antigen-specific T-cell activation. Finally, AiLNPs synthesized with human breast cancer membrane proteins activate DC-mediated antigen-specific T-cell immunity, effectively killing tumor cells. Therefore, AiLNPs are expected to be developed as a patient-specific cancer treatment to prevent cancer recurrence and metastasis.     

A Robustly Supported Extracellular Matrix Improves the Intravascular Delivery Efficacy of Endothelial Progenitor Cells

A major barrier in the multi-purpose use of implantable materials is an incomplete integration with surrounding tissues, causing foreign body reactions, such as fibrous encapsulation and chronic inflammation. From its viewpoint, a universal method is suggested for cloaking any kind of substrate in specific cell-made extracellular matrices (ECMs) via robust linkages for delivery of therapeutic cells. In addition, the feasibility of ECM-coated substrates as endothelial progenitor cells (EPCs)-laden coronary stent platform for endovascular implantation is investigated. Characteristics and stability of cell-secreted ECMs anchored on a substrate are evaluated, and structural and componential features are revealed similar to those of native ECMs, with enough strength to enable practical uses. The in vitro experiments demonstrated that the ECM coating effectively supports the adhesion, proliferation, and viability of EPCs and has selectively opposite effects on smooth muscle cells. The in vivo experiments using a porcine coronary model supports that ECM-coated stents enable endothelial regeneration and inhibit neointimal growth, and the cell-laden form is more effective than other stents. These results will allow the preparation of tissue-integrating materials containing cellular microenvironments and safely coat surfaces with cells to enable long-term implantation and the continuous managing of chronic diseases.     

Manufacturing feature recognition toward integration with processplanning

Process planning plays a key role by linking CAD and CAM. Its front-end is feature recognition, but feature recognition research has not been in accord with the requirements of process planning. This paper presents an effort for integrating the two activities: feature-based machining sequence generation primarily based on tool capabilities. The system recognizes only manufacturable features by consulting the tool database, and simultaneously constructs dependencies among the features. Then, the A* algorithm is used to search for an optimal machining sequence by the aid of the feature dependencies and a manufacturing cost function.     

Biomimetic Color Changing Anisotropic Soft Actuators with Integrated Metal Nanowire Percolation Network Transparent Heaters for Soft Robotics

To add more functionalities and overcome the limitation in conventional soft robots, highly anisotropic soft actuators with color shifting function during actuation is demonstrated for the first time. The electrothermally operating soft actuators with installed transparent metal nanowire percolation network heater allow easy programming of their actuation direction and instantaneous visualization of temperature changes through color change. Due to the unique direction dependent coefficient of thermal expansion mismatch, the suggested actuator demonstrates a highly anisotropic and reversible behavior with very large bending curvature (2.5 cm^?1) at considerably low temperature (≈40 °C) compared to the previously reported electrothermal soft actuators. The mild operating heat condition required for the maximum curvature enables the superior long‐term stability during more than 10 000 operating cycles. Also, the optical transparency of the polymer bilayer and metal nanowire percolation network heater allow the incorporation of the thermochromic pigments to fabricate color‐shifting actuators. As a proof‐of‐concept, various color‐shifting biomimetic soft robots such as color‐shifting blooming flower, fluttering butterfly, and color‐shifting twining tendril are demonstrated. The developed color‐shifting anisotropic soft actuator is expected to open new application fields and functionalities overcoming the limitation of current soft robots.     

Density-Dependent Differentiation of Tonsil-Derived Mesenchymal Stem Cells into Parathyroid-Hormone-Releasing Cells

Mesenchymal stem cells (MSCs) can differentiate into endoderm lineages, especially parathyroid-hormone (PTH)-releasing cells. We have previously reported that tonsil-derived MSC (T-MSC) can differentiate into PTH-releasing cells (T-MSC-PTHCs), which restored the parathyroid functions in parathyroidectomy (PTX) rats. In this study, we demonstrate quality optimization by standardizing the differentiation rate for a better clinical application of T-MSC-PTHCs to overcome donor-dependent variation of T-MSCs. Quantitation results of PTH mRNA copy number in the differentiated cells and the PTH concentration in the conditioned medium confirmed that the differentiation efficiency largely varied depending on the cells from each donor. In addition, the differentiation rate of the cells from all the donors greatly improved when differentiation was started at a high cell density (100% confluence). The large-scale expression profiling of T-MSC-PTHCs by RNA sequencing indicated that those genes involved in exiting the differentiation and the cell cycle were the major pathways for the differentiation of T-MSC-PTHCs. Furthermore, the implantation of the T-MSC-PTHCs, which were differentiated at a high cell density embedded in hyaluronic acid, resulted in a higher serum PTH in the PTX model. This standardized efficiency of differentiation into PTHC was achieved by initiating differentiation at a high cell density. Our findings provide a potential solution to overcome the limitations due to donor-dependent variation by establishing a standardized differentiation protocol for the clinical application of T-MSC therapy in treating hypoparathyroidism.     

Stretchable Skin‐Like Cooling/Heating Device for Reconstruction of Artificial Thermal Sensation in Virtual Reality

Along with visual and tactile sensations, thermal sensation by temperature feeling on the skin can provide rich physical information on the environment and objects. With a simple touch of objects, relative temperature can be sensed and even objects can be differentiated with different thermal properties without any visual cue. Thus, artificially reproducing accurate/controllable thermal sensation haptic signals on human epidermis will certainly be a major research area to reconstruct a more realistic virtual reality (VR) environment. In this study, for the first time, a skin‐like, highly soft and stretchable and bi‐functional (both cold and hot sensation) thermo‐haptic device is reported for wearable VR applications with a single device structure (not separate heater and cooler). The skin‐like thermo‐haptic (STH) device can actively cool down and heat up deformable skin surfaces with instantaneous and accurate adjustment of temperature based upon a feedback control algorithm to mimic desirable thermal sensation with 230% stretchability. As a proof‐of‐concept, the STH device is integrated with a finger‐motion tracking glove to provide artificial thermal sensation information to the skin in various situations such as touching cold beer bottles and hot coffee cups in virtual space. This new type of STH device can offer potential implications for next‐generation haptic devices to provide unique thermal information for a more realistic virtual‐world field and medical thermal treatment.