Realization of Curved Circular Nanotubes Using In Situ Monitored Self-Assembly.

Curved fluidic channels with a circular cross-section play an important role in biology, chemistry, and medicine. However, in nanofluidics, a problem that is largely unsolved is the lack of an effective fabrication method for curved circular nanotubes (10-1000 nm). In this work, an electron-beam-induced self-assembly process was applied to achieve fine curved nanostructures for the realization of nanofluidic devices. The diameter of the tube could be precisely controlled by an atomic layer deposition process. Fluid transported through the nanochannels was verified and characterized using a dark-field microscope under an optical diffraction limit size. The fluid flow demonstrates that the liquid's evaporation (vapor diffusion) in the nanochannel generates compressed vapor, which pumps the liquid and pushes it forward, resulting in a directional flow behavior in the ∼100 nm radius of tubes. This phenomenon could provide a useful platform for the development of diverse nanofluidic devices.

Electron Beam Maneuvering of a Single Polymer Layer for Reversible 3D Self-Assembly.

Reversible self-assembly that allows materials to switch between structural configurations has triggered innovation in various applications, especially for reconfigurable devices and robotics. However, reversible motion with nanoscale controllability remains challenging. This paper introduces a reversible self-assembly using stress generated by electron irradiation triggered degradation (shrinkage) of a single polymer layer. The peak position of the absorbed energy along the depth of a polymer layer can be modified by tuning the electron energy; the peak absorption location controls the position of the shrinkage generating stress along the depth of the polymer layer. The stress gradient can shift between the top and bottom surface of the polymer by repeatedly tuning the irradiation location at the nanoscale and the electron beam voltage, resulting in reversible motion. This reversible self-assembly process paves the path for the innovation of small-scale machines and reconfigurable functional devices.

Radiation-induced IL-1ß expression and secretion promote cancer cell migration/invasion via activation of the NF-κB-RIP1 pathway.

Here, we demonstrate that interleukin-1ß (IL-1ß) contributes to the γ-ionizing radiation (IR)-induced increase of migration/invasion in A549 lung cancer cells, and that this occurs via RIP1 upregulation. We initially observed that the protein expression and secreted concentration of IL-1ß were increased upon exposure of A549 cells to IR. We then demonstrated that IR-induced IL-1ß is located downstream of the NF-κB-RIP1 signaling pathway. Treatments with siRNA and specific pharmaceutical inhibitors of RIP1 and NF-κB suppressed the IR-induced increases in the protein expression and secreted concentration of IL-1ß. IL-1Ra, an antagonist of IL-1ß, treatment suppressed the IR-induced epithelial-mesenchymal transition (EMT) and IR-induced invasion/migration in vitro. These results suggest that IL-1ß could regulate IR-induced EMT. We also found that IR could induce the expression of IL-1ß expression in vivo and that of IL-1 receptor (R) I/II in vitro and in vivo. The IR-induced increases in the protein levels of IL-1 RI/II and IL-1ß suggest that an autocrine loop between IL-1ß and IL-1 RI/II might play important roles in IR-induced EMT and migration/invasion. Based on these collective results, we propose that IR concomitantly activates NF-κB and RIP1 to trigger the NF-κB-RIP1-IL-1ß-IL-1RI/II-EMT pathway, ultimately promoting metastasis.

Hybridized Radial and Edge Coupled 3D Plasmon Modes in Self-Assembled Graphene Nanocylinders.

Current graphene-based plasmonic devices are restricted to 2D patterns defined on planar substrates; thus, they suffer from spatially limited 2D plasmon fields. Here, 3D graphene forming freestanding nanocylinders realized by a plasma-triggered self-assembly process are introduced. The graphene-based nanocylinders induce hybridized edge (in-plane) and radial (out-of-plane) coupled 3D plasmon modes stemming from their curvature, resulting in a four orders of magnitude stronger field at the openings of the cylinders than in rectangular 2D graphene ribbons. For the characterization of the 3D plasmon modes, synchrotron nanospectroscopy measurements are performed, which provides the evidence of preservation of the hybridized 3D graphene plasmons in the high precision curved nanocylinders. The distinct 3D modes introduced in this paper, provide an insight into geometry-dependent 3D coupled plasmon modes and their ability to achieve non-surface-limited (volumetric) field enhancements.

Development of a Human-Display Interface with Vibrotactile Feedback for Real-World Assistive Applications.

It is important to operate devices with control panels and touch screens assisted by haptic feedback in mobile environments such as driving automobiles and electric power wheelchairs. A lot of consideration is needed to give accurate haptic feedback, especially, presenting clear touch feedback to the elderly and people with reduced sensation is a very critical issue from healthcare and safety perspectives. In this study, we aimed to identify the perceptual characteristics for the frequency and direction of haptic vibration on the touch screen with vehicle-driving vibration and to propose an efficient haptic system based on these characteristics. As a result, we demonstrated that the detection threshold shift decreased at frequencies above 210 Hz due to the contact pressure during active touch, but the detection threshold shift increased at below 210 Hz. We found that the detection thresholds were 0.30-0.45 gpeak with similar sensitivity in the 80-270 Hz range. The haptic system implemented by reflecting the experimental results achieved characteristics suitable for use scenarios in automobiles. Ultimately, it could provide practical guidelines for the development of touch screens to give accurate touch feedback in the real-world environment.

Electron Irradiation Driven Nanohands for Sequential Origami.

Sequence plays an important role in self-assembly of 3D complex structures, particularly for those with overlap, intersection, and asymmetry. However, it remains challenging to program the sequence of self-assembly, resulting in geometric and topological constrains. In this work, a nanoscale, programmable, self-assembly technique is reported, which uses electron irradiation as "hands" to manipulate the motion of nanostructures with the desired order. By assigning each single assembly step in a particular order, localized motion can be selectively triggered with perfect timing, making a component accurately integrate into the complex 3D structure without disturbing other parts of the assembly process. The features of localized motion, real-time monitoring, and surface patterning open the possibility for the further innovation of nanomachines, nanoscale test platforms, and advanced optical devices.

Self-Assembled 3D Nanosplit Rings for Plasmon-Enhanced Optofluidic Sensing.

Plasmonic sensors are commonly defined on two-dimensional (2D) surfaces with an enhanced electromagnetic field only near the surface, which requires precise positioning of the targeted molecules within hotspots. To address this challenge, we realize segmented nanocylinders that incorporate plasmonic (1-50 nm) gaps within three-dimensional (3D) nanostructures (nanocylinders) using electron irradiation triggered self-assembly. The 3D structures allow desired plasmonic patterns on their inner cylindrical walls forming the nanofluidic channels. The nanocylinders bridge nanoplasmonics and nanofluidics by achieving electromagnetic field enhancement and fluid confinement simultaneously. This hybrid system enables rapid diffusion of targeted species to the larger spatial hotspots in the 3D plasmonic structures, leading to enhanced interactions that contribute to a higher sensitivity. This concept has been demonstrated by characterizing an optical response of the 3D plasmonic nanostructures using surface-enhanced Raman spectroscopy (SERS), which shows enhancement over a 22 times higher intensity for hemoglobin fingerprints with nanocylinders compared to 2D nanostructures.

RIP1 Is a Novel Component of γ-ionizing Radiation-Induced Invasion of Non-Small Cell Lung Cancer Cells.

Abstract: Previously, we demonstrated that γ-ionizing radiation (IR) triggers the invasion/migration of A549 cells via activation of an EGFR-p38/ERK-STAT3/CREB-1-EMT pathway. Here, we have demonstrated the involvement of a novel intracellular signaling mechanism in γ-ionizing radiation (IR)-induced migration/invasion. Expression of receptor-interacting protein (RIP) 1 was initially increased upon exposure of A549, a non-small cell lung cancer (NSCLC) cell line, to IR. IR-induced RIP1 is located downstream of EGFR and involved in the expression/activity of matrix metalloproteases (MMP-2 and MMP-9) and vimentin, suggesting a role in epithelial-mesenchymal transition (EMT). Our experiments showed that IR-induced RIP1 sequentially induces Src-STAT3-EMT to promote invasion/migration. Inhibition of RIP1 kinase activity and expression blocked induction of EMT by IR and suppressed the levels and activities of MMP-2, MMP-9 and vimentin. IR-induced RIP1 activation was additionally associated with stimulation of the transcriptional factor NF-κB. Specifically, exposure to IR triggered NF-κB activation and inhibition of NF-κB suppressed IR-induced RIP1 expression, followed by a decrease in invasion/migration as well as EMT. Based on the collective results, we propose that IR concomitantly activates EGFR and NF-κB and subsequently triggers the RIP1-Src/STAT3-EMT pathway, ultimately promoting metastasis.

Small-Scale Biological and Artificial Multidimensional Sensors for 3D Sensing.

A vast majority of existing sub-millimeter-scale sensors have a planar, 2D geometry as a result of conventional top-down lithographic procedures. However, 2D sensors often suffer from restricted sensing capability, allowing only partial measurements of 3D quantities. Here, nano/microscale sensors with different geometric (1D, 2D, and 3D) configurations are reviewed to introduce their advantages and limitations when sensing changes in quantities in 3D space. This Review categorizes sensors based on their geometric configuration and sensing capabilities. Among the sensors reviewed here, the 3D configuration sensors defined on polyhedral structures are especially advantageous when sensing spatially distributed 3D quantities. The nano- and microscale vertex configuration forming polyhedral structures enable full 3D spatial sensing due to orthogonally aligned sensing elements. Particularly, the cubic configuration leveraged in 3D sensors offers an array of diverse applications in the field of biosensing for micro-organisms and proteins, optical metamaterials for invisibility cloaking, 3D imaging, and low-power remote sensing of position and angular momentum for use in microbots. Here, various 3D sensors are compared to assess the advantages of their geometry and its impact on sensing mechanisms. 3D biosensors in nature are also explored to provide vital clues for the development of novel 3D sensors.

A novel anti-cancer role of ß-apopicropodophyllin against non-small cell lung cancer cells.

We previously reported that podophyllotoxin acetate (PA) inhibits the growth and proliferation of non-small cell lung cancer (NSCLC) cells and also makes them more sensitive to radiation and chemotherapeutic agents. In an attempt to enhance PA activity, we synthesized 34 derivatives based on podophyllotoxin (PPT). Screening of the derivative compounds for anti-cancer activity against NSCLC led to the identification of ß-apopicropodophyllin (APP) as a strong anti-cancer agent. In addition to its role as an immunosuppressive regulator of the T-cell mediated immune response, the compound additionally showed anti-cancer activity against A549, NCI-H1299 and NCI-460 cell lines with IC50 values of 16.9, 13.1 and 17.1 nM, respectively. The intracellular mechanisms underlying the effects of APP were additionally examined. APP treatment caused disruption of microtubule polymerization and DNA damage, which led to cell cycle arrest, as evident from accumulation of phospho-CHK2, p21, and phospho-Cdc2. Moreover, APP stimulated the pro-apoptotic ER stress signaling pathway, indicated by elevated levels of BiP, phospho-PERK, phospho-eIF2α, CHOP and ATF4. We further observed activation of caspase-3, -8 and -9, providing evidence that both intrinsic and extrinsic apoptotic pathways were triggered. In vivo, APP inhibited tumor growth of NSCLC xenografts in nude mice by promoting apoptosis. Our results collectively support a novel role of APP as an anticancer agent that evokes apoptosis by inducing microtubule disruption, DNA damage, cell cycle arrest and ER stress.

Self-Assembled Three-Dimensional Graphene-Based Polyhedrons Inducing Volumetric Light Confinement.

The ability to transform two-dimensional (2D) materials into a three-dimensional (3D) structure while preserving their unique inherent properties might offer great enticing opportunities in the development of diverse applications for next generation micro/nanodevices. Here, a self-assembly process is introduced for building free-standing 3D, micro/nanoscale, hollow, polyhedral structures configured with a few layers of graphene-based materials: graphene and graphene oxide. The 3D structures have been further modified with surface patterning, realized through the inclusion of metal patterns on their 3D surfaces. The 3D geometry leads to a nontrivial spatial distribution of strong electric fields (volumetric light confinement) induced by 3D plasmon hybridization on the surface of the graphene forming the 3D structures. Due to coupling in all directions, resulting in 3D plasmon hybridization, the 3D closed box graphene generates a highly confined electric field within as well as outside of the cubes. Moreover, since the uniform coupling reduces the decay of the field enhancement away from the surface, the confined electric field inside of the 3D structure shows two orders of magnitude higher than that of 2D graphene before transformation into the 3D structure. Therefore, these structures might be used for detection of target substances (not limited to only the graphene surfaces, but using the entire volume formed by the 3D graphene-based structure) in sensor applications.

In Situ Monitored Self-Assembly of Three-Dimensional Polyhedral Nanostructures.

The self-assembly of 3D nanostructures is a promising technology for the fabrication of next generation nanodevices and the exploration of novel phenomena. However, the present techniques for assembly of 3D nanostructures are invisible and have to be done without physical contact, which bring great challenges in controlling the shapes with nanoscale precision. This situation leads to an extremely low yield of self-assembly, especially in 3D nanostructures built with metal and semiconductor materials. Here, an in situ self-assembly process using a focused ion beam (FIB) microscopy system has been demonstrated to realize 3D polyhedral nanostructures from 2D multiple pieces. An excited ion beam in the FIB microscopy system offers not only a visualization of the nanoscale self-assembly process but also the necessary energy for inducing the process. Because the beam energy that induces the self-assembly can be precisely adjusted while monitoring the status of the self-assembly, it is possible to control the self-assembly process with sub-10 nm scale precision, resulting in the realization of diverse 3D nanoarchitectures with a high yield. This approach will lead to state-of-the-art applications utilizing properties of 3D nanostructures in diverse fields.

Γ-Ionizing radiation-induced activation of the EGFR-p38/ERK-STAT3/CREB-1-EMT pathway promotes the migration/invasion of non-small cell lung cancer cells and is inhibited by podophyllotoxin acetate.

Here, we report a new intracellular signaling pathway involved in γ-ionizing radiation (IR)-induced migration/invasion and show that podophyllotoxin acetate (PA) inhibits the IR-induced invasion and migration of A549 cells (a non-small cell lung cancer (NSCLC) cell line). Our results revealed that IR increased the invasion/migration of A549 cells, and this effect was decreased by 10 nM PA treatment. PA also inhibited the expressions/activities of matrix metalloprotase (MMP) -2, MMP-9, and vimentin, suggesting that PA could block the IR-induced epithelial-mesenchymal transition (EMT). The IR-induced increases in invasion/migration were associated with the activation of EGFR-AKT, and PA inhibited this effect. P38 and p44/42 ERK were also involved in IR-induced invasion/migration, and combined treatments with PA plus inhibitors of each MAPK synergistically blocked this invasion/migration. In terms of transcription factors (TFs), IR-induced increases in cyclic AMP response element-binding protein-1 (CREB-1) and signal transducer and activator of transcription 3 (STAT3) increased invasion/migration and EMT. PA also inhibited these transcription factors and then blocked IR-induced invasion/migration. Collectively, these results indicate that IR induces cancer cell invasion/migration by activating the EGFR-p38/ERK-CREB-1/STAT3-EMT pathway and that PA blocks this pathway to inhibit IR-induced invasion/migration.

Self-folding nanostructures with imprint patterned surfaces (SNIPS).

A significant need in nanotechnology is the development of methods to mass-produce three-dimensional (3D) nanostructures and their ordered assemblies with patterns of functional materials such as metals, ceramics, device grade semiconductors, and polymers. While top-down lithography approaches can enable heterogeneous integration, tunability, and significant material versatility, these methods enable inherently two-dimensional (2D) patterning. Bottom-up approaches enable mass-production of 3D nanostructures and their assemblies but with limited precision, and tunability in surface patterning. Here, we demonstrate a methodology to create Self-folding Nanostructures with Imprint Patterned Surfaces (SNIPS). By a variety of examples, we illustrate that SNIPS, either individually or in ordered arrays, are mass-producible and have significant tunability, material heterogeneity, and patterning precision.

Silicon nanowire degradation and stabilization during lithium cycling by SEI layer formation.

Silicon anodes are of great interest for advanced lithium-ion battery applications due to their order of magnitude higher energy capacity than graphite. Below a critical diameter, silicon nanowires enable the ∼300% volume expansion during lithiation without pulverization. However, their high surface-to-volume ratio is believed to contribute to fading of their capacity retention during cycling due to solid-electrolyte-interphase (SEI) growth on surfaces. To better understand this issue, previous studies have examined the composition and morphology of the SEI layers. Here we report direct measurements of the reduction in silicon nanowire diameter with number of cycles due to SEI formation. The results reveal significantly greater Si loss near the nanowire base. From the change in silicon volume we can accurately predict the measured specific capacity reduction for silicon nanowire half cells. The enhanced Si loss near the nanowire/metal current collector interface suggests new strategies for stabilizing nanowires for long cycle life performance.

Effects of weight management by exercise modes on markers of subclinical atherosclerosis and cardiometabolic profile among women with abdominal obesity: a randomized controlled trial.

BACKGROUND: Few studies have examined the differential effects of weight management by exercise mode on subclinical atherosclerosis. We hypothesized that 3 modes of aerobic, resistance, and combination exercises have differential effects on the flow-mediated dilation (FMD), carotid-femoral pulse wave velocity (PWV), and carotid intima-media thickness (IMT) as well as cardiometabolic profile in weight management. METHODS: A randomized, single-blind trial (ISRCTN46069848) was conducted in Seoul, South Korea between November 2011 and December 2012. Randomized participants were 110 women with abdominal obesity (aerobic group n = 50; resistance group n = 30; combination exercise group n = 30). The treatment period was 12 months with 3-month follow up: A diet-alone intervention for the first 3 months and a diet-plus-exercise intervention for the next 9 months according to exercise modes. The exercise training was designed with an intensity of 50-70% heart rate reserve for 3 days a week in 60-minute-long sessions for 9 months, consisting of 30-minute treadmill and 30-minute bike exercises for aerobic group; upper and lower body exercises with an intensity target of 2 sets and 8-12 repetitions for resistance group; 30-minute resistance and consecutive 30-minute aerobic exercises for combination group. RESULTS: Ninety-two and 49 participants were analyzed for modified intention-to-treat analysis and per-protocol (PP) analysis, respectively. The 3 exercise modes had no significant differential effects on FMD, PWV, and IMT over time; however, the combination group was found to have significantly lower levels of fasting glucose than the aerobic group (p = .034) in the PP analysis. Nevertheless, we observed significant time effects such as reductions in PWV (p = .048) and IMT (p = .018) in cubic and quadratic trends, respectively, and improvements in body weight, waist circumference, low-density and high-density lipoprotein cholesterol levels, fasting glucose levels, and cardiorespiratory fitness in linear, quadratic, or cubic trends. CONCLUSIONS: For women with abdominal obesity, a combination of aerobic and resistance exercises may be preferable to a single exercise mode for effective glucose control. Regardless of exercise mode, exercise interventions combined with dietary interventions in weight management may be beneficial in reducing the risk of subclinical atherosclerosis and cardiometabolic risk.

Health-promoting behaviour among women with abdominal obesity: a conceptual link to social support and perceived stress.

AIM: To identify a conceptual link among health-promoting behaviour, interpersonal support and perceived stress and to examine whether the link between interpersonal support and health-promoting behaviour would be mediated by perceived stress among women with abdominal obesity. BACKGROUND: Abdominal obesity is a strong risk factor for cardiovascular disease in women and its reduction can be achieved by weight loss. Adopting health-promoting behaviour may be critical for successful weight loss. DESIGN: A cross-sectional, correlational study design. METHOD: Study participants were 126 women with abdominal obesity, who comprised a baseline sample in the Community-based, Heart and Weight Management Trial. The Data were collected between September 2010-November 2011. A multiple regression analysis and Sobel's test were performed. FINDINGS: Higher levels of interpersonal support and lower levels of perceived stress were significantly associated with higher levels of health-promoting behaviour, after controlling for age, obesity-related comorbidity, postmenopausal status and current smoking in the regression models. The association between interpersonal support and health-promoting behaviour was significantly mediated by perceived stress in the Sobel's test; the magnitude of the association between interpersonal support and health-promoting behaviour decreased when adding perceived stress to the predictor variables in the regression model. CONCLUSION: Our findings indicate the practical significance of identifying the levels of interpersonal support and perceived stress among women seeking weight management interventions. Nurses need to develop effective strategies for enhancing social support and stress management skills in weight management interventions for facilitating health-promoting behaviour.

Enhanced lithium ion battery cycling of silicon nanowire anodes by template growth to eliminate silicon underlayer islands.

It is well-known that one-dimensional nanostructures reduce pulverization of silicon (Si)-based anode materials during Li ion cycling because they allow lateral relaxation. However, even with improved designs, Si nanowire-based structures still exhibit limited cycling stability for extended numbers of cycles, with the specific capacity retention with cycling not showing significant improvements over commercial carbon-based anode materials. We have found that one important reason for the lack of long cycling stability can be the presence of milli- and microscale Si islands which typically form under nanowire arrays during their growth. Stress buildup in these Si island underlayers with cycling results in cracking, and the loss of specific capacity for Si nanowire anodes, due to progressive loss of contact with current collectors. We show that the formation of these parasitic Si islands for Si nanowires grown directly on metal current collectors can be avoided by growth through anodized aluminum oxide templates containing a high density of sub-100 nm nanopores. Using this template approach we demonstrate significantly enhanced cycling stability for Si nanowire-based lithium-ion battery anodes, with retentions of more than ~1000 mA·h/g discharge capacity over 1100 cycles.

Self-Assembly for Creating Vertically-Aligned Graphene Micro Helices with Monolayer Graphene as Chiral Metamaterials.

Graphene's emergence enables creating chiral metamaterials in helical shapes for terahertz (THz) applications, overcoming material limitations. However, practical implementation remains theoretical due to fabrication challenges. This paper introduces a dual-component self-assembly technique that enables creating vertically-aligned continuous monolayer graphene helices at microscale with great flexibility and high controllability. This assembly process not only facilitates the creation of 3D microstructures, but also positions the 3D structures from a horizontal to a vertical orientation, achieving an aspect ratio (height/width) of ≈2700. As a result, an array of vertically-aligned graphene helices is formed, reaching up to 4 mm in height, which is equivalent to 4 million times the height of monolayer graphene. The benefit of these 3D chiral structures made from graphene is their capability to infinitely extend in height, interacting with light in ways that are not possible with traditional 2D layering methods. Such an impressive height elevates a level of interaction with light that far surpasses what is achievable with traditional 2D layering methods, resulting in a notable enhancement of optical chirality properties. This approach is applicable to various 2D materials, promising advancements in innovative research and diverse applications across fields.

Iteratively Calibratable Network for Reliable EEG-Based Robotic Arm Control.

Robotic arms are increasingly being utilized in shared workspaces, which necessitates the accurate interpretation of human intentions for both efficiency and safety. Electroencephalogram (EEG) signals, commonly employed to measure brain activity, offer a direct communication channel between humans and robotic arms. However, the ambiguous and unstable characteristics of EEG signals, coupled with their widespread distribution, make it challenging to collect sufficient data and hinder the calibration performance for new signals, thereby reducing the reliability of EEG-based applications. To address these issues, this study proposes an iteratively calibratable network aimed at enhancing the reliability and efficiency of EEG-based robotic arm control systems. The proposed method integrates feature inputs with network expansion techniques. This integration allows a network trained on an extensive initial dataset to adapt effectively to new users during calibration. Additionally, our approach combines motor imagery and speech imagery datasets to increase not only its intuitiveness but also the number of command classes. The evaluation is conducted in a pseudo-online manner, with a robotic arm operating in real-time to collect data, which is then analyzed offline. The evaluation results demonstrated that the proposed method outperformed the comparison group in 10 sessions and demonstrated competitive results when the two paradigms were combined. Therefore, it was confirmed that the network can be calibrated and personalized using only the new data from new users.