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Therapeutic proteins are indispensable for treatment of various human diseases. However, intrinsic short serum half-lives of proteins are still big hurdles for developing new therapeutic proteins or expanding applications of existing ones. Urate oxidase (Uox) is a therapeutic protein clinically used for treatment of hyperuricemia. Due to its short half-life, its application for gout treatment requires prolonging the half-life in vivo. Conjugation of a fatty acid (FA), a serum albumin (SA) ligand, to therapeutic proteins/peptides is an emerging strategy to prolong serum half-life presumably via neonatal Fc receptor (FcRn)–mediated recycling. FA conjugation was proven effective for peptides and small proteins (less than 28 kDa), but not for Uox (140 kDa). We hypothesized that the intramolecular distance in the conjugate of FA and Uox is a critical factor for effective FcRn-mediated recycling. In order to control the intramolecular distance in the conjugate, we varied linker lengths between Uox and palmitic acid (PA). There was a linear correlation between the linker length and serum half-life of PA–conjugated Uox (Uox-PA) conjugates. The longer linker led to about 7-fold greater extension of serum half-life of Uox in mice than the unmodified Uox. The trend in serum half-life extension matched well with that in the tertiary structure formation of FcRn/SA/Uox-PA in vitro. These results demonstrate that the intramolecular distance in the conjugate of Uox and FA governs the stable formation of FcRn/SA/FA-conjugated protein and serum half-life extension in vivo. These findings would also contribute to development of effective FAconjugated therapeutic proteins.

In this paper, we first propose power distribution network (PDN) model of the perforated power and ground (P/G) planes including substrate effects and multiarray through-silicon vias (TSVs) for a silicon interposer. Since it is almost impossible to simulate a high metal density perforated PDN structure, we first suggest a modeling methodology for P/G perforated planes to reduce simulation time significantly with a high accuracy. To obtain the PDN impedance of a silicon interposer faster, we convert the perforated planes to solid planes with a dielectric mixture. The capacitance (C) and conductance (G) component of perforated P/G planes are precisely estimated based on the conformal mapping method. From the estimated C and G, the physical dimension and material properties of the dielectric mixture of solid P/G planes are determined, respectively. Because silicon interposer PDN consists of a periodic structure, we design and analyze the unit cell of a PDN thoroughly. From the unit cell analysis, the electrical characteristic of an entire PDN for a silicon interposer is successfully estimated. The PDN impedance of the proposed solid and perforated P/G planes and simulation time to obtain each PDN impedance are compared and evaluated, respectively. The proposed methodology is validated by a full 3-D electromagnetic (EM) simulation in the frequency range from 0.01 to 20 GHz. We also proposed models of multiarray P/G TSVs that can be applied to the various P/G patterns for a silicon interposer. From the inductance matrix considering current directions, the self- and mutual inductances of TSVs are accurately calculated. Because quasi-transverse electromagnetic mode is propagated through TSVs and the substrate dielectric of a silicon interposer can be regarded as a uniform dielectric, the capacitance and conductance of TSVs can be calculated from the inductance matrix. The proposed model of multiarray TSVs is also analyzed and verified by EM simulations in the frequency range from 0.01 to 20 GHz with a high accuracy.

We report on significant performance enhancements of thin-film transistors based on indium oxide thin-film prepared from aqueous precursor solution. To achieve this improvement, the aqueous indium ...

Herein, a photo-crosslinkable coumarin-containing polymer, poly(7-(4-vinyl-benzyloxyl)-4-methylcoumarin) or PVBMC, was prepared, and its physicochemical and electrical properties as a gate dielectric in organic electronic devices, such as organic thin-film transistor (OTFT) and inverter, was evaluated. The crosslinking of PVBMC by exposure to UV light (365 nm) over time was characterized using Fourier-transform IR and UV–visible spectroscopy. The measured capacitance of the cross-linked PVBMC thin film in a metal-insulator-metal-type capacitor was as high as 36.4 pF/mm2. Pentacene-based OTFT and load-type inverter with the cross-linked PVBMC gate dielectric were prepared, and their electrical responses were evaluated under ambient conditions. The OTFT showed dominant hole charge carrier transport behavior with a field-effect mobility of 1.52 × 10−1 cm2/Vs and negligible hysteresis. The load-type inverter based on the OTFT exhibited moderate static and dynamic switching responses to the applied electrical pulse. These results suggest the potential application of photo-crosslinked PVBMC as a gate dielectric in the fabrication of high-performance OTFT-based devices.

Glucagon-like peptide-1 (GLP-1) is a peptide hormone with tremendous therapeutic potential for treating type 2 diabetes mellitus. However, the short half-life of its native form is a significant drawback. We previously prolonged the plasma half-life of GLP-1 via site-specific conjugation of human serum albumin (HSA) at position 16 of recombinant GLP-1 using site-specific incorporation of p-azido-phenylalanine (AzF) and strain-promoted azide-alkyne cycloaddition (SPAAC). However, the resulting conjugate GLP1_8G16AzF-HSA showed only moderate in vivo glucose-lowering activity, probably due to perturbed interactions with GLP-1 receptor (GLP-1R) caused by the albumin-linker. To identify albumin-conjugated GLP-1 variants with enhanced in vivo glucose-lowering activity, we investigated the conjugation of HSA to a C-terminal region of GLP-1 to reduce steric hindrance by the albumin-linker using two different conjugation chemistries. GLP-1 variants GLP1_8G37AzF-HSA and GLP1_8G37C-HSA were prepared using SPAAC and Michael addition, respectively. GLP1_8G37C-HSA exhibited a higher glucose-lowering activity in vivo than GLP1_8G16AzF-HSA, while GLP1_8G37AzF-HSA did not. Another GLP-1 variant, GLP1_8A37C-HSA, had a glycine to alanine mutation at position 8 and albumin at its C-terminus and exhibited in vivo glucose-lowering activity comparable to that of GLP1_8G37C-HSA, despite a moderately shorter plasma half-life. These results showed that site-specific HSA conjugation to the C-terminus of GLP-1 via Michael addition could be used to generate GLP-1 variants with enhanced glucose-lowering activity and prolonged plasma half-life in vivo.

The number of therapeutic peptides for human treatment is growing rapidly. However, their development faces two major issues: the poor yield of large peptides from conventional solid-phase synthesis, and the intrinsically short serum half-life of peptides. To address these issues, we investigated a platform for the production of a recombinant therapeutic peptide with an extended serum half-life involving the site-specific conjugation of human serum albumin (HSA). HSA has an exceptionally long serum half-life and can be used to extend the serum half-lives of therapeutic proteins and peptides. We used glucagon-like-peptide 1 (GLP-1) as a model peptide in the present study. A &ldquo, clickable&rdquo, non-natural amino acid&mdash, p-azido-l-phenylalanine (AzF)&mdash, was incorporated into three specific sites (V16, Y19, and F28) of a GLP-1 variant, followed by conjugation with HSA through strain-promoted azide&ndash, alkyne cycloaddition. All three HSA-conjugated GLP-1 variants (GLP1_16HSA, GLP1_19HSA, and GLP1_28HSA) exhibited comparable serum half-lives in vivo. However, the three GLP1_HSA variants had different in vitro biological activities and in vivo glucose-lowering effects, demonstrating the importance of site-specific HSA conjugation. The platform described herein could be used to develop other therapeutic peptides with extended serum half-lives.

This paper, for the first time, proposes and verifies a new coaxial silicone rubber socket for high-bandwidth and high-density package test using a fabricated sample. In addition, this paper also characterizes and verifies the coaxial silicone rubber socket. Because of the proposed coaxial socket’s novel coaxial structure, the proposed socket successfully achieves the electrical performance improvement. For verification, we compare the proposed socket and the previous noncoaxial socket in time domain. The proposed socket has greater eye height and eye width in the measured eye diagram than those of the noncoaxial socket. Moreover, the slope in the eye diagram is also improved in the case of the proposed socket. Therefore, the measured eye diagram for the coaxial socket shows the improvement in electrical performances. This paper also characterizes the equivalent RLGC model for the coaxial silicone rubber socket. In order to verify the RLGC model, we compare the insertion losses and eye diagrams from measurement, 3-D electromagnetic simulation, and the proposed RLGC model, respectively. Their insertion losses are comparable up to 20 GHz. Furthermore, the obtained eye diagrams are almost identical at the data rate of 9.6 Gb/s. In conclusion, this paper successfully proposes, verifies, and characterizes a new coaxial silicone rubber socket for the first time.

Increasing the specific capacity and cycle life of graphitic carbon anodes is crucial for realizing high-performance lithium ion batteries. Herein, we introduce a new class of graphitic carbon anodes comprising highly ordered three-dimensional nanostructures decorated with SnO2 nanoparticles. The inch-scale, nanostructured graphitic carbon matrices are prepared by supported pyrolysis of epoxy templates patterned by advanced optical lithography. During the subsequent decoration process, the SnO2 nanoparticles are densely formed on the matrix without agglomeration since the periodic nanostructured matrix provides a homogeneous site for nucleation and growth. The surface coverage of the decorated SnO2 nanoparticles and the mass relative to the graphitic carbon are >80% and ∼50 wt%, respectively. The resulting nanostructured C/SnO2 composite monoliths can be assembled solely into LIB coin cells without the aid of binders and conducting agents. The achieved specific capacity and retention are 692 mAh g−1 and 87.31% (at 70th cycle), respectively, which is superior to those of nanostructured carbon anodes prepared in a similar way.

Polymer nanocomposites with inclusion of ceramic nanofillers have relatively high yield strength, elastic moduli, and toughness that therefore are widely used as functional coating and films for optoelectronic applications. Although the mechanical properties are enhanced with increasing the fraction of nanofiller inclusion, there generally is an upper limit on the amount of nanofiller inclusion because the aggregation of the fillers in the polymer matrix, which typically occurs, degrades the mechanical and/or optical performances above 5 vol % of inclusions. Here, we demonstrate an unconventional polymer nanocomposite composed of a uniformly distributed three-dimensional (3D) continuous ceramic nanofillers, which allows for extremely high loading (∼19 vol %) in the polymer matrix without any concern of aggregation and loss in transparency. The fabrication strategy involves conformal deposition of Al2O3 nanolayer with a precise control in thickness that ranges from 12 to 84 nm on a 3D nanostructured porous...

Two-dimensional (2D) transitional metal oxides (TMOs) are an attractive class of materials due to the combined advantages of high active surface area, enhanced electrochemical properties, and stability. Among the 2D TMOs, 2D tungsten oxide (WO3) nanosheets possess great potential in electrochemical applications, particularly in electrochromic (EC) devices. However, feasible production of 2D WO3 nanosheets is challenging due to the innate 3D crystallographic structure of WO3. Here we report a novel solution-phase synthesis of 2D WO3 nanosheets through simple oxidation from 2D tungsten disulfide (WS2) nanosheets exfoliated from bulk WS2 powder. The complete conversion from WS2 into WO3 was confirmed through crystallographic and elemental analyses, followed by validation of the 2D WO3 nanosheets applied in the EC device. The EC device showed color modulation of 62.57% at 700 nm wavelength, which is 3.43 times higher than the value of the conventional device using bulk WO3 powder, while also showing enhanceme...

High-quality rubrene crystals were directly grown on a polymeric gate dielectric-coated ITO/glass substrate by a simple solution process. Organic field-effect transistors were fabricated based on these rubrene crystals, and their electrical performance was investigated. Atomic force micrographs of the rubrene crystal reveal that its surface has a conventional terrace structure, confirming the well-ordered rubrene molecules. The organic transistor with the rubrene crystal shows the highest charge carrier hole mobility of 3.74 cm2/V·s that can be attributed to the strong π-π overlap between the adjacent rubrene molecules. The device shows a stable static and dynamic electrical stress response under ambient conditions. For evaluating the applicability of the transistor in a logic circuit, a simple load-type inverter is fabricated by combining the rubrene transistor and a 10 MΩ load-resistor, to achieve a clear dynamic switching response up to 100 Hz.

Considering the environmental issues, it is essential to develop highly efficient and recyclable photocatalysts in purification systems. Conventional TiO2 nanoparticles have strong intrinsic oxidizing power and high surface area, but are difficult to collect after use and rarely absorb visible light, resulting in low photocatalytic efficiency under sunlight. Here we develop a new type of highly efficient and recyclable photocatalyst made of a three-dimensional (3D) nanostructured N-doped TiO2 monolith with enhanced visible light absorption. To prepare the sample, an ultrathin TiN layer (∼10 nm) was conformally coated using atomic layer deposition (ALD) on 3D nanostructured TiO2. Subsequent thermal annealing at low temperature (550 °C) converted TiN to anatase phase N-doped TiO2. The resulting 3D N-doped TiO2 showed ∼33% enhanced photocatalytic performance compared to pure 3D TiO2 of equivalent thickness under sunlight due to the reduced bandgap, from 3.2 eV to 2.75 eV through N-doping. The 3D N-doped TiO2 monolith could be easily collected and reused at least 5 times without any degradation in photocatalytic performance.

As a demand for electrical systems with a wide data bandwidth has increased, high-performance packages ensuring high data rates, such as low power double data rate series, have become common. The need for high-performance test sockets has also emerged to test these packages. However, a conventional pogo pin socket has a limited test bandwidth due to the parasitic components arising from its spring. On the other hand, a silicone rubber socket satisfies the wide bandwidth requirement because it has low parasitic components due to high-density conductive metal powders in an elastic silicone rubber. In this paper, we propose an RLGC equivalent circuit model of a silicone rubber socket and first experimentally verify it. The proposed model is experimentally verified in the frequency domain by comparing the insertion loss obtained from the proposed model to the measurement up to 20 GHz. The proposed model is experimentally verified in the time domain by comparing the eye diagrams obtained from the proposed model to the measurement at a data rate of 12.5 Gb/s. Also, the insertion loss of the sockets with varied height, diameter, and pitch is analyzed using the proposed model. The proposed model provides physical insight of a silicone rubber socket, and it allows to determine whether a socket is reliable for testing high performance packages in a short time. It also gives us the idea how to design a high-performance test socket. Furthermore, we discuss the current capacity and life cycle of the silicone rubber socket in terms of signal integrity as well.

This paper compared a coaxial silicone rubber socket and non-coaxial socket for high-performance package test. The silicone rubber socket is a kind of the elastomer test sockets consisting of metal powders in the elastomer material. The noncoaxial silicone rubber socket may have the limited electrical performances due to its pitch. Because the pitch is determined by the package's footprint. For this, the coaxial silicone rubber socket was proposed to provide the improved insertion loss and crosstalk noise. The coaxial silicone rubber socket has extra ground powders around the signal powders to configure the coaxial structure. This coaxial structure has advantages in characteristic impedance matching and crosstalk noise reduction. Therefore, this paper compared the insertion loss and crosstalk for the non-coaxial and coaxial silicone rubber socket.

Therapeutic proteins are indispensable in the treatment of various human diseases. Despite the many benefits of therapeutic proteins, they also exhibit diverse side effects. Therefore, reducing unwanted side effects of therapeutic proteins as well as enhancing their therapeutic efficacy are very important in developing therapeutic proteins. Urate oxidase (UOX) is a therapeutic enzyme that catalyzes the conversion of uric acid (UA) into a soluble metabolite, and it is used clinically for the treatment of hyperuricemia. Since UA degradation by UOX generates H2O2 (a cytotoxic side product), UOX was co-delivered with catalase-mimic nanoparticles (AuNPs) using biocompatible pluronic-based nanocarriers (NCs) to effectively reduce H2O2-associated toxicity in cultured cells and to enhance UA degradation efficiency in vivo. Simple temperature-dependent size changes of NCs allowed co-encapsulation of both UOX and AuNPs at a high loading efficiency without compromising critical properties, resulting in efficient modulation of a mixing ratio of UOX and AuNPs encapsulated in NCs. Co-localizing UOX and AuNPs in the NCs led to enhanced UA degradation and H2O2 removal in vitro, leading to a great reduction in H2O2-associated cytotoxicity compared with UOX alone or a free mixture of UOX and AuNPs. Furthermore, we demonstrated that co-delivery of UOX and AuNPs using NCs significantly improves in vivo UA degradation compared to simple co-injection of free UOX and AuNPs. More broadly, we showed that biocompatible pluronic-based nanocarriers can be used to deliver a target therapeutic protein along with its toxicity-eliminating agent in order to reduce side effects and enhance efficacy.

N-doped TiO 2 was further doped with SiO 2 to prepare SiO 2 /N-doped TiO 2 photoelectrodes with high activity in the visible region. A sol-gel process was employed to produce nanoparticles of SiO 2 /N-doped TiO 2 . The addition of SiO 2 to the metal oxide enhanced charge transfer and reduced charge recombination. With the addition of sufficient amounts of SiO 2 and N, the photoelectrodes exhibited a high surface area and strong absorption of light because of their altered absorptivity in the visible wavelength region. These characteristics enabled the production of photoelectrodes with increased charge transfer and reduced charge recombination, resulting in dye-sensitized solar cells (DSSCs) with enhanced J sc values. The SiO 2 /N-doped TiO 2 photoelectrodes were characterized using a range of analysis techniques. After the J-V curve measurements, the DSSCs fabricated with the 0.1 mM SiO 2 /N-doped TiO 2 photoelectrodes exhibited the highest energy conversion efficiency of 8.68%, which was approximately 3% higher than that of the N-doped TiO 2 control groups. This high energy efficiency with the addition of SiO 2 might be due to the enhanced surface area of the photoelectrodes, allowing more dye absorption, and a decrease in electron recombination.

Development of fast and intuitive detection techniques for explosive vapors is highly desired for security applications. Among those techniques, fluorescence quenching has advantages in terms of portability and maintenance cost compared to electrically driven platforms. One of the challenging issues is the restricted sensitivity (i.e., low initial quenching and quenching saturation) caused by hindered diffusion of gaseous analytes inside a dense, solid film, and resulting limited surface area, where the target molecules are reacting. Here, multilevel 3D porous nanostructures are introduced, which possess strong fluorescence and enhanced sensing abilities, produced by a rapid and scalable lithographic technique. The cyanostilbene fluorophore with low-absorption around patterning wavelengths (≈355 nm) is newly designed to be incorporated into transparent photopolymer. The emission color and intensity of the composite films under excitation can be precisely controlled by adjusting the concentration of fluorophore based on intermolecular effects. The patterned, monolithic film with low-volume fraction (

Dynamic partitioning of de novo purine biosynthetic enzymes into multienzyme compartments, purinosomes, has been associated with increased flux of de novo purine biosynthesis in human cells. However, we do not know of a mechanism by which de novo purine biosynthesis would be downregulated in cells. We have investigated the functional role of AMP-activated protein kinase (AMPK) in the regulation of de novo purine biosynthesis because of its regulatory action on lipid and carbohydrate biosynthetic pathways. Using pharmacological AMPK activators, we have monitored subcellular localizations of six pathway enzymes tagged with green fluorescent proteins under time-lapse fluorescence single-cell microscopy. We revealed that only one out of six pathway enzymes, formylglycinamidine ribonucleotide synthase (FGAMS), formed spatially distinct cytoplasmic granules after treatment with AMPK activators, indicating the formation of single-enzyme self-assemblies. In addition, subsequent biophysical studies using fluorescence recovery after photobleaching showed that the diffusion kinetics of FGAMS were slower when it localized inside the self-assemblies than within the purinosomes. Importantly, high-performance liquid chromatographic studies revealed that the formation of AMPK-promoted FGAMS self-assembly caused the reduction of purine metabolites in HeLa cells, indicating the downregulation of de novo purine biosynthesis. Collectively, we demonstrate here that the spatial sequestration of FGAMS by AMPK is a mechanism by which de novo purine biosynthesis is downregulated in human cells.

The influence of Cu doping on the function of dye-sensitized solar cells (DSSCs) dependent on Cu/N-doped TiO 2 photoelectrodes was examined. Cu/N-doped TiO 2 photoelectrodes with diverse Cu concentration were synthesized using the sol–gel process. Upon adequate addition of Cu, the nanoparticles exhibited small particle sizes, high surface area, and a significant red alteration of their absorption to the visible region in relation to Degussa P25 nanomaterials. Furthermore, the traces of Cu/N-doped TiO 2 nanoparticles enhanced the charge transfer and reduced the charge recombination. The addition of sufficient Cu and N increased the surface area, elevating the dye adsorption degree, and decreasing the level of electron recombination. A DSSC fabricated with a 1 mM Cu/N-doped TiO 2 nanoparticles accomplished 11.35% of the highest power conversion efficiency, with a short-circuit current of 22.5 mA/cm 2 . The energy conversion efficiency of this photoelectrode was approximately 37% greater than that of the control, Degussa P25. The increased energy efficiency can be resulted from the extension in surface area, which enabled larger dye charging amount, and the deduction in charge recombination, which accelerated the charge transfer.

Conjugation of serum albumin or one of its ligands (such as fatty acid) has been an effective strategy to prolong the serum half-lives of drugs via neonatal Fc receptor (FcRn)&ndash, mediated recycling of albumin. So far, fatty acid (FA) has been effective in prolonging the serum half-lives for therapeutic peptides and small proteins, but not for large therapeutic proteins. Very recently, it was reported a large protein conjugated to FA competes with the binding of FcRn with serum albumin, leading to limited serum half-life extension, because primary FA binding sites in serum albumin partially overlap with FcRn binding sites. In order to prevent such competition, longer linkers between FA and the large proteins were required. Herein, we hypothesized that small proteins do not cause substantial competition for FcRn binding to albumin, resulting in the extended serum half-life. Using a small protein (28 kDa), we investigated whether the intramolecular distance in FA-protein conjugate affects the FcRn binding with albumin and serum half-life using linkers with varying lengths. Unlike with the FA-conjugated large protein, all FA-conjugated small proteins with different linkers exhibited comparable the FcRn binding to albumin and extended serum half-life.

Alzheimer&rsquo, s disease (AD) is a progressive neurodegenerative disorder characterized by cognitive deficits, neuroinflammation, and neuronal death. The primary pathogenic cause is believed to be the accumulation of pathogenic amyloid beta (A&beta, ) assemblies in the brain. Ghrelin, which is a peptide hormone predominantly secreted from the stomach, is an endogenous ligand for the growth hormone secretagogue-receptor type 1a (GHS-R1a). MK-0677 is a ghrelin agonist that potently stimulates the GHS-R1a ghrelin receptor. Interestingly, previous studies have shown that ghrelin improves cognitive impairments and attenuates neuronal death and neuroinflammation in several neurological disorders. However, it is unknown whether MK-0677 can affect A&beta, accumulation or A&beta, mediated pathology in the brains of patients with AD. Therefore, we examined the effects of MK-0677 administration on AD-related pathology in 5XFAD mice, an A&beta, overexpressing transgenic mouse model of AD. MK-0677 was intraperitoneally administered to three-month-old 5XFAD mice. To visualize A&beta, accumulation, neuroinflammation, and neurodegeneration, thioflavin-S staining and immunostaining with antibodies against A&beta, (4G8), ionized calcium-binding adaptor molecule 1 (Iba-1), glial fibrillary acidic protein (GFAP), neuronal nuclear antigen (NeuN), and synaptophysin were conducted in the neocortex of 5XFAD and wild-type mice, and to evaluate changes of phosphorylated cyclic adenosine monophosphate (cAMP) response element binding protein (pCREB) levels, immunostaining with antibody against pCREB was performed in dentate gyrus of the hippocampus of 5XFAD and wild-type mice. The histological analyses indicated that MK-0677-treated 5XFAD mice showed reduced A&beta, deposition, gliosis, and neuronal and synaptic loss in the deep cortical layers, and inhibited the decrement of pCREB levels in dentate gyrus of the hippocampus compared to vehicle-treated 5XFAD mice. Our results showed that activation of the ghrelin receptor with MK-0677 inhibited the A&beta, burden, neuroinflammation, and neurodegeneration, which suggested that MK-0677 might have potential as a treatment of the early phase of AD.

Zirconium was newly utilized as a post-treatment material for photoelectrodes in dye-sensitized solar cells (DSSCs), and DSSCs with a high energy conversion efficiency were developed. The Zr oxide-post-treated TiO2 photoelectrodes were prepared by dipping Degussa P25 in a Zr butoxide solution, followed by calcination for 30 min at 475 °C. In the prepared sample, the particle size decreased, and the specific surface area increased, leading to improved dye adsorption. Zr oxide-post-treatment formed ZrO2 on TiO2 surfaces and the electron transport increased by the formation. This post-treatment decreased the recombinant ratio of electrons by reducing resistance in the interparticle electrode/dye/electrolyte. The energy conversion efficiency of Zr oxide-post-treated TiO2 photoelectrodes was 7.03%, which is a 61% improvement over P25 photoelectrodes and is similar to that of TiCl4-post-treated TiO2 photoelectrodes (7.28%). This enhanced energy conversion efficiency could be attributed to the increased surface area, which enabled higher dye loading, and to the improved interparticle connections, which enhanced charge transport and reduced charge recombination.

In this paper, silicon/glass/organic interposers for 2.5D/3D interconnects are investigated for signal integrity analysis. As total system bandwidth increases, memory industry has been developed to satisfy its requirements. Therefore, High Bandwidth Memory (HBM) is introduced to the market. HBM enables TeraByte/s bandwidth with extremely fine pitch, short interconnects using Through Silicon Via (TSV) within the limited area. In HBM based graphics module needs silicon interposer to route between processor and memory due to its capability to process narrow signal width and space. However, silicon interposer has its limits in cost issue. Thus, various interposer substrates are introduced and compared as a substitution for the silicon interposer. Glass interposer has relatively closely-matched Coefficient of Thermal Expansion (CTE). Organic interposer can be fabricated with lower cost than the others. To compare these various substrates, signal integrity analyses must be performed. Especially, HBM has wide number of I/Os for achieving TB/s bandwidth. In this case, metal space should be narrower and it increases the crosstalk effects. Time-domain simulations are performed and analyzed based on the eyediagrams. Eye-diagram opening voltage and timing jitter are important signal integrity indexes. To obtain the channels' characteristics, all proposed structures are simulated by 3D Full Electromagnetic (EM) simulator, ANSYS HFSS, and circuit simulator, Agilent Advanced Design System, up to 10Gbps.

A variety of biophysical and biochemical factors control stem cell differentiation. In this study, we developed a nanopatterned substrate platform to surface immobilize osteoinductive bone morphogenetic protein-2 (BMP-2) peptides. Specifically, polyurethane acrylate (PUA) substrates with nanometer-scale groove- and dot-shaped topography were fabricated. The nanopatterned PUA surface was uniformly coated with poly(glycidyl methacrylate) (pGMA) by initiated chemical vapor deposition (iCVD) followed by covalent immobilization of BMP-2 peptides. This approach resulted in much more efficient BMP-2 peptide immobilization than physical adsorption. The combined effects of biochemical signals from BMP-2 peptides and nanotopographical stimulation on osteogenic differentiation of hMSCs were examined in culture with and without soluble osteogenic factors. Results of Alizarin Red S staining, immunostaining, and quantitative real-time polymerase chain reaction revealed that hMSCs cultured on nanopatterned surfaces with immobilized BMP-2 peptides exhibited greater potential for osteogenic differentiation than hMSCs on a flat surface. Furthermore, the nanopatterned substrates with BMP-2 peptides directed osteogenic differentiation of hMSCs even without osteogenesis soluble inducing factors. Substrates with nanotopography and bioactive signals that induce differentiation of stem cells towards specific lineages could be used to develop functional stem cell culture substrates and tissue engineered scaffolds for therapeutic applications.

We propose, for the first time, an explicit semiconductor physics-based through-silicon via (TSV) capacitance–voltage (CV) model. The effect of TSV CV hysteresis is demonstrated in the model, and the TSV capacitance is modeled with respect to dc bias voltage and the dimension of the TSV. The proposed model is verified by comparison to the measurement results. The effect of hysteresis in the model correlates well with the measurement results. This model can be utilized in a circuit level simulation to expand the possible application of the model to, but not limited to, hierarchical power distribution network impedance analysis, RC delay analysis, input–output power consumption analysis, and crosstalk and eye diagram simulation in any 3-D-IC systems using TSVs.

Motivated by the increasing market demand for the high performance mobile devices, both the data rate and the number of pin of mixed-signal systems keep on increasing to realize multifunctional yet compact system designs. With this ascending technical trend, many signal integrity (SI) and power integrity (PI) problems such as ISI, jitter, crosstalk, simultaneous switching noise (SSN) have arisen that need to be thoroughly analyzed and tested. In order to accurately monitor the data signals of LPDDR4, a carefully designed test interposer considering such factors as impedance matching, minimization of skew and crosstalk needs to be proposed. In this paper, a novel test interposer scheme composed of a test interposer and silicone rubber sheets is proposed for LPDDR4 memory test. Through a series of simulations and measurements, we experimentally verify the proposed structures in time and frequency domains, and prove their accuracy and practicality.

In this paper, an eye diagram of the 8B/10B encoded signal is estimated by using the single bit response (SBR) of a silicone rubber socket. The 8B/10B encoding scheme has been used in the HDMI. Because the eye diagram heavily depends on the bit patterns, the encoded PRBS patterns should be considered when the resultant eye diagram is obtained. Likewise, the 8B/10B encoding scheme must also considered when the eye diagram is estimated. An eye diagram estimation method finds the worst contour of the eye diagram using partial information. This can be done in significantly reduced testing time by using a SBR, as opposed to all of PRBS patterns. In high-speed IC tests, the ICs are interconnected with an automated test environment (ATE) by test sockets. Since the resultant eye diagram consists of 8B/10B encoded signal, the eye diagram should be estimated considering the encoding scheme. This paper considers the mapping scheme of Lattice RD 1012. In conclusion, the eye diagram of the 8B/10B encoded signal by Lattice RD 1012 is estimated using the SBR of the silicone rubber socket under the various compression effect. The estimated eye diagram and simulated eye diagram of the encoded PBRS patterns are nearly identical. Therefore, the proposed eye diagram estimation including the conventional 8B/10B encoding scheme is verified by comparing with that of PRBS patterns.

In this paper, electrical performances of a silicone rubber socket are experimentally verified using several measurement set-ups. Silicone rubber socket is a promising test socket that can be adopted in high-speed testing environments in place of pogo type sockets, due to it relatively shorter length and lower inductance. However, the electrical performance of silicone rubber socket is dependent on an external force because its substrate is an elastic polymer. Accordingly, the compression effect causes reliability problems of testing environments, which needs to be thoroughly evaluated to ensure reliability. In this paper, two measurement set-ups for evaluating the performance of silicone rubber sockets are introduced and compared. Firstly, double-sided measurement set-up is introduced. However, it is unsuitable for high-speed testing environments due to the coupling effects between the closely placed microwave probes. For this reason, this paper introduces another measurement set-up which uses an additional printed circuit board (PCB). The second measurement set-up evaluates the electrical performance of the silicone rubber socket by comparing the performances of the PCB only and the PCB with the silicone rubber socket. While the measured electrical performance of the second set-up is much worse because of the parasitic elements of the PCB, use of an additional PCB is more reliable than the double-sided measurement result. Using this configuration, the electrical performance of the silicone rubber socket is evaluated up to 110GHz.

The methodology suggested in this research provides the great possibility of creating nanostructures composed of various materials, such as soft polymer, hard polymer, and metal, as well as Si. Such nanostructures are required for a vast range of optical and display devices, photonic components, physical devices, energy devices including electrodes of secondary batteries, fuel cells, solar cells, and energy harvesters, biological devices including biochips, biomimetic or biosimilar structured devices, and mechanical devices including micro- or nano-scale sensors and actuators.

Here we propose a concept of conductive dry adhesives (CDA) combining a gecko-inspired hierarchical structure and an elastomeric carbon nanocomposite. To complement the poor electrical percolation of 1D carbon nanotube (CNT) networks in an elastomeric matrix at a low filler content (∼1 wt %), a higher dimensional carbon material (i.e., carbon black, nanographite, and graphene nanopowder) is added into the mixture as an aid filler. The co-doped graphene and CNT in the composite show the lowest volume resistance (∼100 ohm·cm) at an optimized filler ratio (1:9, total filler content: 1 wt %) through a synergetic effect in electrical percolation. With an optimized conductive elastomer, gecko-inspired high-aspect-ratio (3) microstructures over a large area (∼4 in.(2)) are successfully replicated from intaglio-patterned molds without collapse. The resultant CDA pad shows a high normal adhesion force (∼1.3 N/cm(2)) even on rough human skin and an excellent cycling property for repeatable use over 30 times without degradation of adhesion force, which cannot be achieved by commercial wet adhesives. The body-attachable CDA can be used as a metal-free, all-in-one component for measuring biosignals under daily activity conditions (i.e., underwater, movements) because of its superior conformality and water-repellent characteristic.

In this study, accurate nanostructures with various aspect ratios are created on several types of material. This work is highly applicable to the energy, optical, and nano-bio fields, for example. A silicon (Si) nano-mold is preserved using the method described, and target nanostructures are replicated reversibly and unlimitedly to or from various hard and soft materials. It is also verified that various materials can be applied to the substrates. The results confirm that the target nanostructures are successfully created in precise straight line structures and circle structures with various aspect ratios, including extremely high aspect ratios of 1:18. It is suggested that the optimal replicating and demolding process of nanostructures with high aspect ratios, which are the most problematic, could be controlled by means of the surface energy between the functional materials. Relevant numerical and analytical studies are also performed. It is possible to expand the applicability of the nanostructured mold by adopting various backing materials, including rounded substrates. The scope of the applications is extended further by transferring the nanostructures between different species of materials including metallic materials as well as identical species.

In this paper, we propose and analyze an equivalent RLGC model of silicone rubber socket with single-ended signaling. A silicone rubber socket consists of highly dense metal powders in elastic silicone rubber. When the silicone rubber is compressed, metal powders form a column which corresponds to a pad of package. Thus, it can be modeled as a pair of cylinders. We have successfully verified the proposed model using a 3D electromagnetic (EM) solver in frequency domain and the eye diagram measurement in time domain. As a result, the verified model can be used to determine whether socket is applicable to the test system in the simulation level concurrently with offering physical insight and reducing time spent 3D EM simulating socket.

In this paper, structural and electrical characteristic deviations of silicone rubber sockets are analyzed depending on external force based on its lumped RLGC model. Electrical performances heavily depend on compression rate of the silicone rubber socket. Thus, study on the structural and electrical characteristic deviations of the silicone rubber socket depending on external force is needed for reliable tests. The deviations are analyzed based on an assumption based simplified equivalent model of the silicone rubber socket. For verification, a 3D electromagnetic (EM) simulation program is used and its results are compared with that of proposed RLGC models in the frequency domain. The electrical performance of the RLGC model is nearly identical to that of 3D EM simulation result. In addition, the electrical performance of the compressed silicone rubber socket is also nearly identical to that of a solder ball when it is compressed at different compression ratio.

In this paper, an RLGC model of a silicone rubber socket is proposed and compared with simulation results. Due to the reusability of the silicone rubber socket, it is suitable for a reliable test. In addition, its electrical performance is compared with that of conventional solder balls. The performance of the two are compared using measurements in both frequency and time domains. Their eye diagrams are nearly identical at the data rate of 28Gbps, which is the data rate of a single channel in a 100Gbps transceiver IC that consists of 4 parallel channels.

The methodology suggested in this research provides the great possibility of creating nanostructures composed of various materials, such as soft polymer, hard polymer, and metal, as well as Si. Such nanostructures are required for a vast range of optical and display devices, photonic components, physical devices, energy devices including electrodes of secondary batteries, fuel cells, solar cells, and energy harvesters, biological devices including biochips, biomimetic or biosimilar structured devices, and mechanical devices including micro- or nano-scale sensors and actuators.

The methodology suggested in this research provides the great possibility of creating nanostructures composed of various materials, such as soft polymer, hard polymer, and metal, as well as Si. Such nanostructures are required for a vast range of optical and display devices, photonic components, physical devices, energy devices including electrodes of secondary batteries, fuel cells, solar cells, and energy harvesters, biological devices including biochips, biomimetic or biosimilar structured devices, and mechanical devices including micro- or nano-scale sensors and actuators.

We developed a 4.5” 192x64 active matrix organic light‐emitting diode display on a glass using organic thin‐film transistor (OTFT) switching‐arrays with two transistors and a capacitor in each sub‐pixel. The OTFTs has bottom contact structure with a unique gate insulator and pentacene for the active layer. The width and length of the switching OTFT is 800 ? and 10? respectively and the driving OTFT has 1200? channel width with the same channel length. On/off ratio, mobility, on‐current of switching OTFT and on‐current of driving OTFT were 106,0.3∼0.5 cm2/V•sec, order of 10 μA and over 100 μA, respectively. AMOLEDs composed of the OTFT switching arrays and OLEDs made using vacuum deposition method were fabricated and driven to make moving images, successfully.

Copper (Cu) wire has been highlighted as a low cost material for use in thermosonic ball bonding for various package (PKG) groups. This wire has already been applied in high-end PKGs such as BGA, QFP and QFN in mass production, and the volume is feasible. Not only the advantage of a low cost material, but Cu wire has other merits which include higher electrical conductivity and a much slower inter-metallic compound (IMC) growth rate than Gold (Au) wire.

A method for inscribing surface relief gratings in azopolymer thin films via proximity field nanopatterning is reported. Azopolymers prepared by ring opening metathesis polymerization were cast as thin films and brought into conformal contact with transparent polydimethylsiloxane phase masks. Irradiation of the film surface through the phase masks induces mass transport of azopolymer that generates surface relief structures on the basis of the intensity modulation of the light by structures on the phase mask. The experimental images obtained matched well with those produced by optical simulation. A wide variety of structures could be inscribed in the film surface which depended on the molecular weight of the azopolymer and irradiation time. Control experiments conducted suggest that the process is entirely photonic and that the presence of the phase mask on the film surface did not affect the inscription process.

Nowadays, due to the increment in Gold prices, Copper wire is considered as a low cost material for use in various package groups. Some packages, with a low-pin count of thick size wire, have already succeeded in mass production using Copper wire. In addition, Copper wire has been applied in high-end packages such as BGA, QFP and QFN in small masses, and that production volume is feasible. However, the applications for Copper wire require different conditions from those of Gold wire, due to differences in basic characteristics, such as hardness or the tail breaking force of each metal. These characteristics are a barrier delaying the universal application of Copper wire to the same degree as Gold wire. The main barrier to Copper wire application is 1st bonding problem, for example metal off or pad cratering, and low 2nd workability resulting from frequent bonding errors such as short tail or NSOL(Non Stick on Lead). Therefore, the purpose of this study is to identify methods for hardness reduction and improvements in 2nd workability to solve the application limitations of Copper wire through wire improvement. Our results identified, firstly for FAB(Free Air Ball) or bonded ball hardness for Copper wire, the optimum composition and content to reduce hardness. In addition, regarding the low 2nd workability, the Copper wire tail bond has a lower value and bigger deviation than Gold wire in bondability between the Copper wire and the 2nd lead. To improve this, a study has been conducted on controlling wire manufacturing processes and alloy composition to dramatically increase uniformity of microstructure. Fine and uniform grains of Copper wire were achieved by microstructure control to minimize the quality gap in the product. Furthermore, it is helpful to reduce bonding errors during the 2nd bond, resulting from wire grain uniformity. We have revealed that improvements in Copper wire show increased workability and stable bonding performance, when tested on QFN, QFP and BGA.

The pattern resolution of soft lithographic techniques is critically determined by the elastic modulus of the soft mold that can support fine and high-aspect-ratio features with conformal adhesion to target substrates. We present a strategy to fine-tune the elastic modulus of conformal molds made of polyurethane acrylate by optimizing the chemical structures and the composition of prepolymer and modulator. Trimethylolpropane ethoxylated (15) triacrylate plays a key role as a delicate modulator for increasing the elastic modulus of soft aliphatic urethane diacrylate oligomer with its low cross-linking density. The optimized molds have sufficiently high elastic modulus (>23 MPa) for defect-free replication of dense, high-aspect-ratio (>2) nanopillars and nanotrench structures while still preserving their conformality. The conformal mold with good mechanical and optical properties can serve as a semi-permanently usable optical phase mask with a wide range of phase modulations for generating three-dimensional (3D) nanostructures with high precision.