Fabrication of mixed-scale PMMA (Polymethyl methacrylate) fluidic device via thermal nanoimprint using a convex carbon mold

Department of Mechanical EngineeringRecently micro-/nanofluidic devices are widely used for various research areas including biological, chemical, and biomedical applications. Such mixed-scale micro-/nanofluidic devices are generally fabricated using photolithography and direct writing methods (e. g., e-beam lithography or focused ion beam milling) in series. However, the direct writing methods require high cost and long process time thus resulting in low throughput issue. PDMS (Polydimethylsiloxane) replication can overcome the low throughput issues. The PDMS replication method consists of a PDMS casting process on a pre-patterned mold and a subsequent curing processes. By this method, PDMS mixed-scale channel patterns can be replicated repeatedly, thus, total throughput of fabricated mixed-scale PDMS fluidic device is enhanced. However, the channel size is smaller, the more PDMS channels are collapsed due to the low Young???s modulus and hardness of PDMS. In this study, I developed the fabrication method of mixed-scale PMMA (Poly methyl methacrylate) fluidic device via simple thermal nanoimprint using a monolithic mixed-scale convex carbon mold (microchannel mold: width = ~ 50 ???m, height = ~ 5 ???mnanochannel mold: width = ~ 600 nm, height = ~ 60 nm). The monolithic carbon mold was fabricated using carbon-MEMS consisting of two step photolithography processes and one step pyrolysis. In pyrolysis, polymer structures shrank dramatically and thus microscale photoresist structures were converted into sub-micro- or nanoscale carbon structures. In nanoimprint process, the shape of the monolithic mixed-scale convex carbon mold was transferred into a PMMA sheet while the polymer sheet was heated. After demolding the carbon mold from the patterned PMMA sheet, the patterns were accurately transferred on the PMMA sheet (microchannel: width = ~ 50 ???m, height = ~ 5 ???mnanochannel: width = ~ 600 nm, height = ~ 60 nm). The pyrolyzed carbon mold could be easily demolded because of its curved side walls resulting from anisotropic volume reduction in pyrolysis. This special side wall geometry and good robustness of the carbon mold ensured reproducibility in nanoimprint. The mixed-scale channels were sealed by another thin PMMA sheet with low pressure and heat after oxygen plasma treatment. PMMA has higher Young???s modulus compared to PDMS (polydimethylsiloxane) so that the PMMA channels ensured consistent nanochannel fabrication and operation without channel collapse. The PMMA mixed-scale fluidic device was used to entrap single particles via diffusiophoresis. In the fluidic device, microchannels and nanochannels were smoothly connected via Kingfisher-beak-shaped 3D microfunnels that were converted from polymer triangular prims via pyrolysis. By filling two microchannels that are connected via multiple nanochannels with high concentration solution and low concentration solution respectively and controlling pressure difference between two microchannels, local concentration gradients can occur near the 3D microfunnels at the microchannel with low concentration. The localized concentration gradients generate local electric fields resulting in diffusiophoresisthe motion of charged particles along the localized electric fields. In this experiment, 1 ??m-diameter charged single particles dispersed in the low concentrate solution were dragged from the microchannel into the 3D microfunnels via diffusiophoresis. Consequently, the unique 3D microfunnel worked as a chamber where single particle was entrappedthus, single particles could be entrapped without external electric force in 3D microfunnels. The diffusiophoresis-based single particle entrapment experiment showed the potential of the mixed-scale channel networks as a single cell research tool.ope

Theology of Global Citizenship: Belonging Beyond Boundaries, God Within Boundaries

Though creating identity and belongingness under the sovereign requires an enclosure by boundaries, the very act of drawing boundaries imposes inevitable challenges. The limitations of the Westphalian system based on territorial boundaries are becoming more tangible with transnational flows threatening individual’s sense of belonging and the state’s exercise of sovereignty. Global citizenship is suggested as a possible “solution” transcending these arbitrarily drawn boundaries. Nonetheless, my political theological examination concludes that global citizenship is yet another translation of the human beings’ old wish for belonging to, protection from, and unity under a “god,” albeit with new boundaries that differentiate us from them

3D Capture and 3D Contents Generation for Holographic Imaging

The intrinsic properties of holograms make 3D holographic imaging the best candidate for a 3D display. The holographic display is an autostereoscopic display which provides highly realistic images with unique perspective for an arbitrary number of viewers, motion parallax both vertically and horizontally, and focusing at different depths. The 3D content generation for this display is carried out by means of digital holography. Digital holography implements the classic holographic principle as a two‐step process of wavefront capture in the form of a 2D interference pattern and wavefront reconstruction by applying numerically or optically a reference wave. The chapter follows the two main tendencies in forming the 3D holographic content—direct feeding of optically recorded digital holograms to a holographic display and computer generation of interference fringes from directional, depth and colour information about the 3D objects. The focus is set on important issues that comprise encoding of 3D information for holographic imaging starting from conversion of optically captured holographic data to the display data format, going through different approaches for forming the content for computer generation of holograms from coherently or incoherently captured 3D data and finishing with methods for the accelerated computing of these holograms

MAMo: Leveraging Memory and Attention for Monocular Video Depth Estimation

We propose MAMo, a novel memory and attention frame-work for monocular video depth estimation. MAMo can augment and improve any single-image depth estimation networks into video depth estimation models, enabling them to take advantage of the temporal information to predict more accurate depth. In MAMo, we augment model with memory which aids the depth prediction as the model streams through the video. Specifically, the memory stores learned visual and displacement tokens of the previous time instances. This allows the depth network to cross-reference relevant features from the past when predicting depth on the current frame. We introduce a novel scheme to continuously update the memory, optimizing it to keep tokens that correspond with both the past and the present visual information. We adopt attention-based approach to process memory features where we first learn the spatio-temporal relation among the resultant visual and displacement memory tokens using self-attention module. Further, the output features of self-attention are aggregated with the current visual features through cross-attention. The cross-attended features are finally given to a decoder to predict depth on the current frame. Through extensive experiments on several benchmarks, including KITTI, NYU-Depth V2, and DDAD, we show that MAMo consistently improves monocular depth estimation networks and sets new state-of-the-art (SOTA) accuracy. Notably, our MAMo video depth estimation provides higher accuracy with lower latency, when omparing to SOTA cost-volume-based video depth models.Comment: Accepted at ICCV 202

Four dimensional motility tracking of biological cells by digital holographic microscopy

Abstract: We utilize digital holography microscopy to track cellular motility in four dimensions. The three-dimensional trajectories have been measured as a function of time at sub-second and micro level. Digital holography microscopy (DHM) has been widely utilized in the biomedical field DHM setup used in this work is illustrated in Three-dimensional profiles of microspheres We present three-dimensional profiles of microspheres in Three-dimensional profiles of microfibers Three-dimensional profiles of microfibers are shown in FTu5A.3.pdf Frontiers in Optic

Coprinus comatus Cap Inhibits Adipocyte Differentiation via Regulation of PPARγ and Akt Signaling Pathway

This study assessed the effects of Coprinus comatus cap (CCC) on adipogenesis in 3T3-L1 adipocytes and the effects of CCC on the development of diet-induced obesity in rats. Here, we showed that the CCC has an inhibitory effect on the adipocyte differentiation of 3T3-L1 cells, resulting in a significant decrease in lipid accumulation through the downregulation of several adipocyte specific-transcription factors, including CCAAT/enhancer binding protein β, C/EBPδ, and peroxisome proliferator-activated receptor gamma (PPARγ). Moreover, treatment with CCC during adipocyte differentiation induced a significant down-regulation of PPARγ and adipogenic target genes, including adipocyte protein 2, lipoprotein lipase, and adiponectin. Interestingly, the CCC treatment of the 3T3-L1 adipocytes suppressed the insulin-stimulated Akt and GSK3β phosphorylation, and these effects were stronger in the presence of an inhibitor of Akt phosphorylation, LY294002, suggesting that CCC inhibited adipocyte differentiation through the down-regulation of Akt signaling. In the animal study, CCC administration significantly reduced the body weight and adipose tissue weight of rats fed a high fat diet (HFD) and attenuated lipid accumulation in the adipose tissues of the HFD-induced obese rats. The size of the adipocyte in the epididymal fat of the CCC fed rats was significantly smaller than in the HFD rats. CCC treatment significantly reduced the total cholesterol and triglyceride levels in the serum of HFD rats. These results strongly indicated that the CCC-mediated decrease in body weight was due to a reduction in adipose tissue mass. The expression level of PPARγ and phospho-Akt was significantly lower in the CCC-treated HFD rats than that in the HFD obesity rats. These results suggested that CCC inhibited adipocyte differentiation by the down-regulation of major transcription factor involved in the adipogenesis pathway including PPARγ through the regulation of the Akt pathway in 3T3-L1 cells and HFD adipose tissue

Design of a Multiband Antenna for LTE/GSM/UMTS Band Operation

This paper proposes a multiband antenna for LTE/GSM/UMTS band operation. The proposed antenna consists of a meandered planar inverted-F antenna with an additional branch line for wide bandwidth and a folded-loop antenna. The antenna provides a wide bandwidth to cover the hepta-band LTE/GSM/UMTS operation. The measured 6 dB return loss bandwidth is 169 MHz (793–962 MHz) at the low-frequency band and 1030 MHz (1700–2730 MHz) at the high-frequency band. The overall dimension of the proposed antenna is 55 mm × 110 mm × 5 mm

Feeding state-dependent regulation of developmental plasticity via CaMKI and neuroendocrine signaling

Information about nutrient availability is assessed via largely unknown mechanisms to drive developmental decisions, including the choice of Caenorhabditis elegans larvae to enter into the reproductive cycle or the dauer stage. In this study, we show that CMK-1 CaMKI regulates the dauer decision as a function of feeding state. CMK-1 acts cell-autonomously in the ASI, and non cell-autonomously in the AWC, sensory neurons to regulate expression of the growth promoting daf-7 TGF-β and daf-28 insulin-like peptide (ILP) genes, respectively. Feeding state regulates dynamic subcellular localization of CMK-1, and CMK-1-dependent expression of anti-dauer ILP genes, in AWC. A food-regulated balance between anti-dauer ILP signals from AWC and pro-dauer signals regulates neuroendocrine signaling and dauer entry; disruption of this balance in cmk-1 mutants drives inappropriate dauer formation under well-fed conditions. These results identify mechanisms by which nutrient information is integrated in a small neuronal network to modulate neuroendocrine signaling and developmental plasticity. © Neal et al.1

Recognition of Transmembrane Protein 39A as a Tumor-Specific Marker in Brain Tumor

Transmembrane protein 39A (TMEM39A) belongs to the TMEM39 family. TMEM39A gene is a susceptibility locus for multiple sclerosis. In addition, TMEM39A seems to be implicated in systemic lupus erythematosus. However, any possible involvement of TMEM39A in cancer remains largely unknown. In the present report, we provide evidence that TMEM39A may play a role in brain tumors. Western blotting using an anti-TMEM39A antibody indicated that TMEM39A was overexpressed in glioblastoma cell lines, including U87-MG and U251-MG. Deep-sequencing transcriptomic profiling of U87-MG and U251-MG cells revealed that TMEM39A transcripts were upregulated in such cells compared with those of the cerebral cortex. Confocal microscopic analysis of U251-MG cells stained with anti-TMEM39A antibody showed that TMEM39A was located in dot-like structures lying close to the nucleus. TMEM39A probably located to mitochondria or to endosomes. Immunohistochemical analysis of glioma tissue specimens indicated that TMEM39A was markedly upregulated in such samples. Bioinformatic analysis of the Rembrandt knowledge base also supported upregulation of TMEM39A mRNA levels in glioma patients. Together, the results afford strong evidence that TMEM39A is upregulated in glioma cell lines and glioma tissue specimens. Therefore, TMEM39A may serve as a novel diagnostic marker of, and a therapeutic target for, gliomas and other cancers