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This is a study on the loading spectrum for full-scale fatigue testing of composite aircraft structures. Fatigue tests are performed to confirm the durability and damage tolerance of a composite aircraft structure. In particular, as composite materials have fatigue life variance larger than that of metallic materials, it takes a considerable amount of time to complete the aforementioned tests. Investigation of key factors such as spectrum truncation and load enhancement is required to create a load spectrum that can reasonably shorten the test time. In other words, criteria for removing the loads that have little effect on the fatigue life and applying factors for the severe load spectrum should be studied to produce the optimal load spectrum, which depends on the fatigue characteristics of the composite material. In this study, coupon tests and statistical analyses of carbon fiber/epoxy composites were performed to analyze the key elements and establish the criteria for the reliable truncation level and load factor for an optimal loading spectrum.

Graphical abstract: Fluorine-induced surface modification passivates surface defects on the ZnO surface, which improves the photovoltaic performance and ZnO/perovskite interface stability

Silk contains an adhesive glycoprotein, silk sericin, in which silk fibroins can be enfolded and chemically stabilized. Silk sericin is gaining importance as the material for the creation of functional bioscaffolds. However, the assembly of silk sericin is generally limited to the blend of polymers or proteins due to its inherent poor mechanical strength. Here, we report a simple macroscopic controlled assembly of silk sericin fibers based on their secondary structure via wet-spinning. In addition, plasticization of silk sericin using glycerol immobilized with glutaraldehyde was found to induce dimensional stability, affording stable linear fibers with self-adhesion. Furthermore, cyclo-phenylalanine nanowires were incorporated into the silk sericin dope for a practical demonstration of their potential in artificial silk production with superstructure formation. The physicochemical characteristics of the spun fibers have also been elucidated using Fourier-transform infrared spectroscopy, electron microscopy, tensile test, differential scanning calorimetry, and 2D X-ray diffraction.

The assembly of one-dimensional nanomaterials into macroscopic fibers can improve mechanical as well as multifunctional performance. Double-walled aluminogermanate imogolite nanotubes are geo-inspired analogues of carbon nanotubes, synthesized at low temperature, with complementary properties. Here, continuous imogolite-based fibers are wet-spun within a poly(vinyl alcohol) matrix. The lyotropic liquid crystallinity of the system produces highly aligned fibers with tensile stiffness and strength up to 24.1 GPa (14.1 N tex–1) and 0.8 GPa (0.46 N tex–1), respectively. Significant enhancements over the pure polymer control are quantitatively attributed to both matrix refinement and direct nanoscale reinforcement, by fitting an analytical model. Most intriguingly, imogolite-based fibers show a high degree of healability viaevaporation-induced self-assembly, recovering up to 44% and 19% of the original fiber tensile stiffness and strength, respectively. This recovery at high absolute strength highlights a general strategy for the development of high-performance healable fibers relevant to composite structures and other applications.

The p‐type nanowire field‐effect transistor (FET) with a SiGe shell channel on a Si core is optimally designed and characterized using in‐depth technology computer‐aided design (TCAD) with quantum models for sub‐10‐nm advanced logic technology. SiGe is adopted as the material for the ultrathin shell channel owing to its two primary merits of high hole mobility and strong Si compatibility. The SiGe shell can effectively confine the hole because of the large valence‐band offset (VBO) between the Si core and the SiGe channel arranged in the radial direction. The proposed device is optimized in terms of the Ge shell channel thickness, Ge fraction in the SiGe channel, and the channel length (Lg) by examining a set of primary DC and AC parameters. The cutoff frequency (fT) and maximum oscillation frequency (fmax) of the proposed device were determined to be 440.0 and 753.9 GHz when Lgis 5 nm, respectively, with an intrinsic delay time (τ) of 3.14 ps. The proposed SiGe‐shell channel p‐type nanowire FET has demonstrated a strong potential for low‐power and high‐speed applications in 10‐nm‐and‐beyond complementary metal‐oxide‐semiconductor (CMOS) technology.

A new flexible design concept of dual-band RASs is presented and discussed. The new design concept can provide a simple and useful fabrication method. A case study demonstrated the ability of the proposed approach to overcome the limits encountered in previous studies related to the finite design of RASs. To obtain various optimal RAS design solutions using lossy materials, Glass/CNT-EP composites whose permittivity was controlled simply by varying the manufacturing pressure were demonstrated. The feasibility of RASs based on these composite materials with adjustable permittivity was studied at both single- and dual-band frequencies. The structures demonstrated enhanced performance compared to conventional materials. Various design solutions using both single- and double-slab absorbers were obtained on the basis of their properties. Thus, the proposed design method based on the controllable characteristics of CNT-added composite materials is used to enhance the absorption performance of RASs through a flexible design at both single- and dual-band frequencies.

ABSTRACTObjectives: A tearable dissolving microneedle system (TD-MN system) was developed for shortening the time required to administer drugs into the skin through the dissolving microneedles.Methods: TD-MN system consisted of an array of tearable dissolving microneedles (TD-MN) and micro-pillars. The microneedle tips had a female part to integrate with the micro-pillars. The micro-pillars exerted a vertical force to cause the separation of the tips from the base. The separation force exerted by six TD-MN arrays with different thicknesses of separation region was measured. The TD-MN system with trypan blue was inserted into porcine skin to observe the separation of the microneedle tips, and then calcein was added separately to observe drug diffusion into the skin.Results: The thickness of the tearable region and the depth of the female part were a function of the concentration and volume of the molding solution. The separation force increased as the thickness of the tearable region increased. Nine tips were successfully separated from the base by applying a force of through the micro-pillars.Conclusions: The TD-MN system could provide immediate administration of a drug, resulting in improved patient convenience as well as delivery of the correct drug dose.

The end-cap removal of carbon nanotubes (CNTs) refers to the structural modification method that makes inner-core spaces and voids between walls accessible. Specifically, the accommodation of alkali metal cations in those hidden surfaces for electrochemical energy storage has been a challenging task. Here we present open-ended vertically aligned CNTs (VA-CNTs) as an ideal structure for Li+accommodation, which were produced by chemical vapor deposition, followed by CF4reactive ion etching. A model study suggests a link between Li+capacity and the surface area, more specifically, allows us to estimate the amount of additional Li+accommodation, which is 2.3 times increased after end-cap removal. The relatively high capacity (889 mAh/g) has confirmed that open-ended VA-CNTs are highly active for Li+ intercalation as well as exposing interior surfaces, which can be compared to the control (338 mAh/g). The microstructural change observation combined with spectroscopic studies reveals that poor Li+reversibility stems from the solid–electrolyte interface (SEI) layer formation on the interior and exterior walls of the CNTs, which results in poor initial Coulombic efficiency (∼23.3%) and cyclic stability (48.6%) after 50 cycles. The significant capacity fades after the first cycle due to the accelerated formation of the SEI layer in the presence of a heteroatom, which degrades Li+and electron mobility. The exposed inner-core space provides significant increased surface area as expected, but confined inner-core space leads to poor reversibility with channel blockage.

Fiber nanomaterials can become fundamental devices that can be woven into smart textiles, for example, miniaturized fiber-based supercapacitors (FSCs). They can be utilized for portable, wearable electronics and energy storage devices, which are highly prospective areas of research in the future. Herein, we developed porous carbon nanotube–graphene hybrid fibers (CNT–GFs) for all-solid-state symmetric FSCs, which were assembled through wet-spinning followed by a hydrothermal activation process using environmentally benign chemicals (i.e., H2O2and NH4OH in deionized water). The barriers that limited effective ion accessibility in GFs were overcome by the intercalation of CNTs in the GFs which enhanced their electrical conductivity and mechanical properties as well. The all-solid-state symmetric FSCs of a precisely controlled activated hybrid fiber (a-CNT–GF) electrode exhibited an enhanced volumetric capacitance of 60.75 F cm–3compared with those of a pristine CNT–GF electrode (19.80 F cm–3). They also showed a volumetric energy density (4.83 mWh cm–3) roughly 3 times higher than that of untreated CNT–GFs (1.50 mWh cm–3). The excellent mechanical flexibility and structural stability of a miniaturized a-CNT–GF are highlighted by the demonstration of negligible differences in capacitance upon bending and twisting. The mechanism of developing porous, large-scale, low-cost electrodes using an environmentally benign activation method presented in this work provides a promising route for designing a new generation of wearable, portable miniaturized energy storage devices.

This paper aims to investigate the characteristics of concrete exposed to early frost damage and to examine the relationships between compressive strength and static and dynamic elastic moduli concerning its exposure to various frost environments. Frost initiation occurred at 1, 2, 3, 4, and 7 d, with duration of 12, 24, 36 h at − 10 ℃. Furthermore, electric arc furnace slag coarse aggregate (EFG) was used as coarse aggregate to compare its influence on the properties of natural crushed coarse aggregate (NCA). Compressive strength and static elastic modulus were measured, and a nondestructive evaluation method approach was employed to evaluate the dynamic elastic modulus. The experimental results confirmed that a significant decrease in compressive strength when the concrete is exposed to frost damage in the early stages, particularly for 24 h in low w/b. However, the early age frost damage did not significantly alter the static and dynamic elastic moduli compared to the change observed in the compressive strength. Moreover, considering the impact of early frost damage on both compressive strength and elastic modulus, a new stochastic equation was proposed. This equation can utilize the results of nondestructive evaluation to estimate the compressive strength of early frost damaged concrete.

We designed cyclosilazane-type silicon precursors and proposed a three-step plasma-enhanced atomic layer deposition (PEALD) process to prepare silicon nitride films with high quality and excellent step coverage. The cyclosilazane-type precursor, 1,3-di-isopropylamino-2,4-dimethylcyclosilazane (CSN-2), has a closed ring structure for good thermal stability and high reactivity. CSN-2 showed thermal stability up to 450 °C and a sufficient vapor pressure of 4 Torr at 60 °C. The energy for the chemisorption of CSN-2 on the undercoordinated silicon nitride surface as calculated by density functional theory method was −7.38 eV. The PEALD process window was between 200 and 500 °C, with a growth rate of 0.43 Å/cycle. The best film quality was obtained at 500 °C, with hydrogen impurity of ∼7 atom %, oxygen impurity less than 2 atom %, low wet etching rate, and excellent step coverage of ∼95%. At 300 °C and lower temperatures, the wet etching rate was high especially at the lower sidewall of the trench pattern. We introduced the three-step PEALD process to improve the film quality and the step coverage on the lower sidewall. The sequence of the three-step PEALD process consists of the CSN-2 feeding step, the NH3/N2plasma step, and the N2plasma step. The H radicals in NH3/N2plasma efficiently remove the ligands from the precursor, and the N2plasma after the NH3plasma removes the surface hydrogen atoms to activate the adsorption of the precursor. The films deposited at 300 °C using the novel precursor and the three-step PEALD process showed a significantly improved step coverage of ∼95% and an excellent wet etching resistance at the lower sidewall, which is only twice as high as that of the blanket film prepared by low-pressure chemical vapor deposition.

In this work, a novel structure FinFET having an ultra-thin SiGe shell channel forming a heterojunction with Si core is proposed and characterized, with an emphasis on high-speed operation capability in the tera-hertz (THz) regime, by 3-dimensional (3-D) device simulation. The proposed device is operated in the p-type enhancement mode and the ultra-thin SiGe channel confines the mobile holes very effectively by the help of the valence band offset (VBO) between SiGe channel and Si core. The simulations with multiple drift and diffusion models and quantum mechanical models for higher accuracy allow to predict the minimum channel thickness and Ge content of 2 nm and 40%, respectively, for suppressing the hole leakage outflowing over the VBO. Also, scalability was checked down to 5 nm for achieving the upcoming logic technology nodes. Cut-off frequency (fT) and maximum oscillation frequency (fmax) are obtained to be 240 GHz and 1.04 THz at a low drive voltage as −0.7 V, respectively.

The mechanical properties of rodlike cellulose nanocrystals (CNCs) suggest great potential as bioderived reinforcement in (nano)composites. Poly(vinyl alcohol) (PVOH) is a useful industrial material and very compatible with CNC chemistry. High performance CNC/PVOH composite fibers were produced coaxial coagulation spinning, followed by hot-drawing. We showed that CNCs increase the alignment and crystallinity of PVOH, as well as providing direct reinforcement, leading to enhanced fiber strength and stiffness. At 40 wt % CNC loading, the strength and stiffness reached 880 MPa and 29.9 GPa, exceeding the properties of most other nanocellulose based composite fibers previously reported.

We report the plasma-enhanced atomic layer deposition (PEALD) of silicon nitride thin film using a silylamine compound as the silicon precursor. A series of silylamine compounds were designed by replacing SiH3groups in trisilylamine by dimethylaminomethylsilyl or trimethylsilyl groups to obtain sufficient thermal stability. The silylamine compounds were synthesized through redistribution, amino-substitution, lithiation, and silylation reactions. Among them, bis(dimethylaminomethylsilyl)trimethylsilyl amine (C9H29N3Si3, DTDN2-H2) was selected as the silicon precursor because of the lowest bond dissociation energy and sufficient vapor pressures. The energies for adsorption and reaction of DTDN2-H2 with the silicon nitride surface were also calculated by density functional theory. PEALD silicon nitride thin films were prepared using DTDN2-H2 and N2plasma. The PEALD process window was between 250 and 400 °C with a growth rate of 0.36 Å/cycle. The best film quality was obtained at 400 °C with a RF power of 100 W. The PEALD film prepared showed good bottom and sidewall coverages of ∼80% and ∼73%, respectively, on a trench-patterned wafer with an aspect ratio of 5.5.

Idiopathic pulmonary fibrosis (IPF) is a progressive, eventually fatal disease characterized by fibrosis of the lung parenchyma and loss of lung function. IPF is believed to be caused by repetitive alveolar epithelial cell injury and dysregulated repair process including uncontrolled proliferation of lung (myo) fibroblasts and excessive deposition of extracellular matrix proteins in the interstitial space; however, the pathogenic pathways involved in IPF have not been fully elucidated. In this study, we attempted to characterize metabolic changes of lung tissues involved in the pathogenesis of IPF using gas chromatography–mass spectrometry-based metabolic profiling. Partial least-squares discriminant analysis (PLS-DA) model generated from metabolite data was able to discriminate between the control subjects and IPF patients (R2X= 0.37, R2Y= 0.613 and Q2(cumulative) = 0.54, receiver operator characteristic AUC > 0.9). We discovered 25 metabolite signatures of IPF using both univariate and multivariate statistical analyses (FDR < 0.05 and VIP score of PLS-DA > 1). These metabolite signatures indicated alteration in metabolic pathways: adenosine triphosphate degradation pathway, glycolysis pathway, glutathione biosynthesis pathway, and ornithine aminotransferase pathway. The results could provide additional insight into understanding the disease and potential for developing biomarkers.

Two-dimensional (2D) Janus transition metal dichalcogenides (TMDCs) are highly attractive as an emerging class of 2D materials, but only a few methods are available for fabricating them. These methods rely on the initial growth of 2D TMDCs in one process, followed by an additional plasma or high-temperature (T) process. To overcome these drawbacks, we employ the new approach of NaCl-assisted single-process chemical vapor deposition, which consists of three steps that proceed only by altering the temperature in situ. In the first step, MoS2is deposited onto a SiO2/Si substrate with the Mo and S atoms activated in different temperature zones. In the second step, S vacancies are formed in the upper layer of the grown MoS2by annealing. In the third step, the vacancies are filled with activated Se atoms. Throughout the steps, NaCl lowers the melting point of the constituent atoms, while the T in each zone is properly controlled. The growth mechanism is clarified by a separate annealing experiment that does not involve a supply of activated atoms. These results highlight a simple and cost-effective approach for growing Janus MoSSe, which is more useful for fundamental studies and device applications.

Three-dimensional (3D) topological semimetals (TSMs) are a new class of Dirac materials that can be viewed as 3D graphene and are referred to as Dirac semimetals (DSMs) or Weyl semimetals (WSMs) depending on whether time reversal symmetry and/or inversion symmetry are protected, respectively. Despite some interesting results on Dirac- to Weyl-semimetal phase transitions under conditions of low temperature or strong magnetic field (B), all of them are reversible phenomena. Here, we report for the first time a possible permanent transition in a single TSM by ion implantation. A Dirac- to Weyl-semimetal phase transition in a Bi0.96Sb0.04DSM results from inversion-symmetry breaking induced by implantation with nonmagnetic Au ions for implant fluences (ϕG) ≥ 3.2 × 1016Au cm−2. This phenomenon is evidenced by the ϕG-dependent behavior of the Raman spectra and quantum-oscillation parameters extracted from magnetoresistance (MR) measurements, which show abrupt changes at ϕG≥ 3.2 × 1016Au cm−2. The verification of the transition is further supported by observations of negative MR in the longitudinal B // electric field orientation, indicating the existence of a chiral anomaly in Weyl fermions induced by implantation with nonmagnetic Au ions. In contrast, implantation with magnetic Mn ions exhibits no such particular behavior. Our findings demonstrate the first realization of a possible permanent DSM-to-WSM phase transition in a single material by the simple approach of implantation using nonmagnetic elements.

Electrochemical oxygen redox reactions are the crucial elements for energy conversion and storage including fuel cells and metal air batteries. Despite tremendous research efforts, developing high-efficient, low-cost, and durable bifunctional oxygen catalysts remains a major challenge. We report a new class of hybrid material consisting of subnanometer thick amorphous cobalt hydroxide anchored on NCNT as a durable ORR/OER bifunctional catalyst. Although amorphous cobalt species-based catalysts are known as good OER catalysts, hybridizing with NCNT successfully enhanced ORR activity by promoting a 4e reduction pathway. Abundant charge carriers in amorphous cobalt hydroxide are found to trigger the superior OER activity with high current density and low Tafel slope as low as 36 mV/decade. A remarkably high OER turnover frequency (TOF) of 2.3 s–1at an overpotential of 300 mV was obtained, one of the highest values reported so far. Moreover, the catalytic activity was maintained over 120 h of cycling. The unique subnanometer scale morphology of amorphous hydroxide cobalt species along with intimate cobalt species–NCNT interaction minimizes the deactivation of catalyst during prolonged repeated cycles.

To better understand the respiratory lipid phenotypes of asthma, we developed a novel method for lipid profiling of bronchoalveolar lavage fluid (BALF) using HPLC-QTOF-MS with an internal spectral library and high-throughput lipid-identifying software. The method was applied to BALF from 38 asthmatic patients (18 patients with nonsteroid treated bronchial asthma [NSBA] and 20 patients with steroid treated bronchial asthma [SBA]) and 13 healthy subjects (NC). We identified 69 lipids, which were categorized into one of six lipid classes: lysophosphatidylcholine (LPC), phosphatidylcholine (PC), phosphatidylglycerol (PG), phosphatidylserine (PS), sphingomyelin (SM) and triglyceride (TG). Compared with the NC group, the individual quantity levels of the six classes of lipids were significantly higher in the NSBA subjects. In the SBA subjects, the PC, PG, PS, SM, and TG levels were similar to the levels observed in the NC group. Using differentially expressed lipid species (pvalue < 0.05, FDR < 0.1 and VIP score of PLS-DA > 1), 34 lipid biomarker candidates with high prediction performance between asthmatics and controls were identified (AUROC > 0.9). These novel findings revealed specific characteristics of lipid phenotypes in asthmatic patients and suggested the importance of future research on the relationship between lipid levels and asthma.

We investigated the effects of hydrogen gas flow rate in the cooling step of CVD on graphene film. We discovered that hydrogen gas in the cooling step influences the quality of graphene. The D peak (defects of graphene) intensity of the Raman spectrum tends to increase with an increasing hydrogen flow rate. Whether methane gas as a hydrocarbon source is maintained during the cooling step or not, the hydrogen flow rate during the cooling step strongly affects the quality of CVD-grown graphene.

This paper addresses a low damage-transfer method using epoxy bonding. In this method, first, graphene/metal film and a target substrate are bonded using epoxy; etching of the metal substrate follows. This method is free of organic particles caused by PMMA, and no cracks are spotted, which cracks are a major concern in the PMMA-transfer method. Raman data show that the epoxy-transferred graphene films have a higher 2D/G intensity ratio and a narrower 2D FWHM than those of films transferred by PMMA, if the epoxy is cured optimally. The Raman spectrum of the epoxy-transferred graphene showed G band splitting, probably due to the strain effect. This method is useful for the transfer of large area-graphene films.

Introduction Numerous studies on cam femoroacetabular impingement (FAI) causing osteoarthritis have been conducted in Western populations, but not in Asian populations. The alpha angle in cam type FAI can be measured by routine hip AP and axial radiographs. The purpose of this study was to determine the range of alpha angles in an asymptomatic Asian cohort.Materials and Methods We performed a retrospective examination on 500 asymptomatic Asian adults (1000 hips) who underwent simultaneous spine MRI and hip coronal survey MRI for evaluation of back pain from December 2009 to March 2010. The alpha angle was measured on anteroposterior (AP) pelvic survey images. According to inclusion criteria, 372 hips of 186 men and 622 hips of 311 women were analysed.Results The mean alpha angles for men and women were 50.61° ± 7.61° and 49.82° ± 4.14°, respectively with no statistically significant differences (p = 0.063). Alpha angles of the two age groups (≥50 years old and <50 years old) were similar in both genders: 49.90° ± 6.88° versus 51.40° ± 8.30° in men (p = 0.060), and 50.61° ± 7.61° versus 49.82° ± 4.14° in women (p = 0.71). The frequency of pathologic alpha angle of men and women was 0.5% and 3.1%, respectively.Conclusions After review of 994 asymptomatic adult hips, we found neither gender-specific nor age-specific differences in the alpha angle. The frequency of the pathological range of the alpha angle was notably rare, as compared to those of Western countries. We assume that these findings could be related to a low prevalence of FAI and idiopathic osteoarthritis of the hip in the Asian population.

We report an efficient and environmentally benign biomimetic mineralization of TiO2at the graphitic carbon surface, which successfully created an ideal TiO2/carbon hybrid structure without any harsh surface treatment or interfacial adhesive layer. The N-doped sites at carbon nanotubes (CNTs) successfully nucleated the high-yield biomimetic deposition of a uniformly thick TiO2nanoshell in neutral pH aqueous media at ambient pressure and temperature and generated N-doped CNT (NCNT)/TiO2core/shell nanowires. Unlike previously known organic biomineralization templates, such as proteins or peptides, the electroconductive and high-temperature-stable NCNT backbone enabled high-temperature thermal treatment and corresponding crystal structure transformation of TiO2nanoshells into the anatase or rutile phase for optimized material properties. The direct contact of the NCNT surface and TiO2nanoshell without any adhesive interlayer introduced a new carbon energy level in the TiO2band gap and thereby effectively lowered the band gap energy. Consequently, the created core/shell nanowires showed a greatly enhanced visible light photocatalysis. Other interesting synergistic properties such as stimuli-responsive wettabilites were also demonstrated.

DNA‐Origamistrukturen: Graphenoxidfilme können leicht in Lösung verarbeitet, unter Einwirkung von Licht mit Strukturen versehen und chemisch modifiziert werden. Das Beschichten derart strukturierter Oberflächen mit DNA‐Origamistrukturen erforderte eine hochselektive Adsorption auf dem Graphenoxid (siehe Bild).

Nanoscale folding of DNA: Taking advantage of facile solution processing, pattern formation under light irradiation, and ready chemical modification of graphene oxide, various patterned films of chemically modified graphene were prepared and employed for spatial patterning of DNA origami structures (see picture). The patterning of DNA origami structures required highly selective adsorption on graphene oxide surfaces.

This Feature Article reviews recent progress in the tailored assembly of carbon nanotubes and graphene into three‐dimensional architectures with particular emphasis on our own research employing self‐assembly principles. Carbon nanotubes and graphene can be assembled into macroporous films, hollow spherical capsules, or hollow nanotubes, via directed assembly from solvent dispersion. This approach is cost‐effective and beneficial for large‐scale assembly, but pre‐requests stable dispersion in a solvent medium. Directed growth from a nanopatterned catalyst array is another promising approach, which enables the control of morphology and properties of graphitic materials as well as their assembly. In addition, the aforementioned two approaches can be synergistically integrated to generate a carbon hybrid assembly consisting of vertical carbon nanotubes grown on flexible graphene films. Tailored assembly relying on scalable self‐assembly principles offer viable routes that are scalable for mass production towards the ultimate utilization of graphitic carbon materials in nanoelectronics, displays, sensors, energy storage/conversion devices, and so on, including future flexible devices.

Hey ho, let's GO: Graphene oxide platelets can be self‐assembled into highly ordered, mechanically flexible carbon films with tunable porous morphologies. Further nitrogen doping enhanced the electrical properties and supercapacitor performances of the carbon‐based assemblies, and provided chemical functionalization.

Graphenoxid‐Plättchenkönnen sich zu hoch geordneten und flexiblen Kohlenstoff‐Filmen mit einstellbaren Porenmorphologien organisieren. Durch Dotieren mit Stickstoff werden die elektrischen Eigenschaften und Superkondensator‐Charakteristika der kohlenstoffbasierten Strukturen verbessert, und eine chemische Funktionalisierung wird ermöglicht.

We modeled flexible microelectronic systems and analyzed the stress and strain distribution assuming an international standard bending test evaluating flexible electronics. The flexible microelectronic system consisted of a flexible substrate, a thin silicon die bonded to the substrate using bumps, along with an underfill and molding layer. The highest stress values were found at the square silicon die corners under bending deformation. After rounding the die corners, the copper bumps were the weakest component in the system. When polymer bumps replaced copper bumps to improve the mechanical stability, the critical bending radius reduced from 13.5 mm to 8.0 mm, and the silicon die was again the most vulnerable component. When the die thickness decreased from 50 to 30 μm, the critical bending radius of the flexible system even decreased to 6.9 mm. Therefore, it is advantageous for mechanically reliable flexible microelectronic systems to bond thin silicon dies with rounded corners to a flexible substrate using polymer bumps.

To combine the bioinert titanium with the biological active coating of hydroxyapatite [HA, Ca10(PO4)6(OH)2] a new pulsed laser deposition(PLD) method was applied. The initial osteoblast-like MC3T3-E1 cell response to this thin HA coated(<1μm) surface was compared with non-coated surfaces. Cell responses on four different pure titanium surfaces, such as smooth titanium, HA coated smooth titanium, rough titanium and HA coated rough titanium, were compared. Cell morphology and attachment were examined by scanning electron microscopy after 6, 24 and 72 hrs of culture, cell proliferation by MTS assay after 3, 7 and 14 days. The differentiation of the cells was analyzed by real time PCR up to 21 days. The cells were well spread and attached on all surfaces and showed more irregular shapes on the HA coated specimens. They proliferated continuously on all specimens up to 14 days. Smooth surface specimens showed better cell proliferation than rough ones after 7 days, and the HA coated specimens demonstrated slightly greater MTS activity than the non-coated groups after 14 days. The surface topography affected cell proliferation initially however; there was no significant difference afterwards. Thin HA coating influenced the expression of some genes related with cell differentiation.

Nanosized hydroxyapatite(HAp) was synthesized hydrothermally and influence of processing parameters, such as reaction temperature and time, pH, and Ca/P ratio, on the phase stability of HAp was evaluated after pressureless sintering at 1250°C in air. The highest stability was achieved from the powder obtained at a processing condition for the lowest solubility of Ca2+, which corresponds to temperature close to 200°C, time <4h, pH>9.0, and Ca/P = 1.67. The stability of nanosized HAp in HAp/3Y-TZP composites was slightly inferior to commercial one, but the involvement of hydrothermally synthesized HAp improved sintered density of the composites and stability of t-ZrO2 phase in the composites.

A hydrothermal method has been used to produce nanoparticles of 3 mol% yttria-stabilized tetragonal zirconia (3Y-TZP) with high fracture toughness. The effects of reaction temperature and pH on crystallite size and sintered density, and the influence of Nb2O5 addition into 3Y-TZP on toughness have been investigated. The particle size increased with increasing the processing parameters and the influence of temperature was more significant than pH. The density of nanosized 3Y-TZP increased with increasing pH up to 9 and then decreased abruptly with further increase. The density increased slightly with the reaction temperature up to 140°C and then changed little with increasing temperature. The toughness increased in proportional to the Nb2O5 content. After sintering for 1 h at 1270°C, the highest relative density of 98% was obtained from nanoparticles of about 17 nm, prepared at 200°C and pH 9, and the toughness of 3Y-TZP was increased from 2.5 to 8.3 MPam1/2 by addition of 1.2 mol% Nb2O5.

SiO2 films were prepared by atomic layer deposition (ALD) technique, and their physical and electrical properties were characterized for being applied as a gate insulator of low-temperature polysilicon thin-film transistors. ALD SiO2 films were deposited at 350–400 oC using alternating exposures of SiH2Cl2 and O3/O2, and the characteristics of the deposited films were improved with increasing deposition temperature. The ALD films deposited at 400 oC exhibited integrity, surface roughness and leakage current better than those of the conventional plasma-enhanced chemical vapor deposition (PECVD) films.

The osseointegration rate of a new zirconia/alumina composite ceramic implant material, (Y,Nb)-TZP/ alumina, was compared with conventional titanium implant in the rabbit model. Four different groups of threaded implant were compared after 4 and 6weeks healing period. The bone implant contact ratio and bone volume was evaluated by undecalcified histologic sections. The surface of each implant group was observed under SEM. Within the limitations of this study, Zr/Al composite ceramic implants demonstrated favorable bone response compared to titanium implant. This material demonstrated a possibility of an alternative to titanium dental implant. Further studies are needed to confirm this result.