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BACKGROUND: Bone marrow-derived mesenchymal stem cells (BMSCs) and bone morphogenetic protein-2 (BMP-2) have been studied for bone repair because they have regenerative potential to differentiate into osteoblasts. The development of injectable and in situ three-dimensional (3D) scaffolds to proliferate and differentiate BMSCs and deliver BMP-2 is a crucial technology in BMSC-based tissue engineering. METHODS: The proliferation of mouse BMSCs (mBMSCs) in collagen/poly-γ-glutamic acid (Col/γ-PGA) hydrogel was evaluated using LIVE/DEAD and acridine orange and propidium iodide assays. In vitro osteogenic differentiation and the gene expression level of Col/γ-PGA(mBMSC/BMP-2) were assessed by alizarin red S staining and quantitative reverse-transcription polymerase chain reaction. The bone regeneration effect of Col/γ-PGA(mBMSC/BMP-2) was evaluated in a mouse calvarial bone defect model. The cranial bones of the mice were monitored by micro-computed tomography and histological analysis. RESULTS: The developed Col/γ-PGA hydrogel showed low viscosity below ambient temperature, while it provided a high elastic modulus and viscous modulus at body temperature. After gelation, the Col/γ-PGA hydrogel showed a 3D and interconnected porous structure, which helped the effective proliferation of BMSCs with BMP-2. The Col/γ-PGA (mBMSC/BMP-2) expressed more osteogenic genes and showed effective orthotopic bone formation in a mouse model with a critical-sized bone defect in only 3–4 weeks. CONCLUSION: The Col/γ-PGA(mBMSC/BMP-2) hydrogel was suggested to be a promising platform by combining collagen as a major component of the extracellular matrix and γ-PGA as a viscosity reducer for easy handling at room temperature in BMSC-based bone tissue engineering scaffolds. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s13770-022-00454-4.

A flexible radio-frequency (RF) antenna allows wearable smart devices to have various functionalities. To develop a high-performance RF antenna, an outstanding radiation efficiency should be achieved. Metallic films are commonly utilized in RF antenna electrodes owing to their high electrical conductivity, which is related to the radiation efficiency. However, their high density and low mechanical stability under deformed states, such as the folding of metallic films, hinder their use as flexible RF antenna electrodes. In this study, we fabricated a carbon-nanotube (CNT) film via the direct-spinning method for use in a flexible RF antenna electrode. The network structure of the CNT film endows it with a high electrical conductivity and allows it to be freestanding without a polymeric binder. The freestanding CNT film-based RF antenna attained a high radiation efficiency of 85.6%, commercially useable level, and its performance remained stable even under mechanical deformation, such as bending and folding. This high performance is attributed to the network structure of the CNT film composed of pure CNT bundles.

This paper aims to cost-effectively improve the energy efficiency of large vessels in shipping by the optimum design of propeller boss cap fins (PBCFs). First, a model propeller of the modern four-blade propeller in a Ro-Ro ship, with no boss cap fin in its original design, is experimentally and numerically investigated. The computational fluid dynamics (CFD) model reproduced all the experiments very well. Then, the CFD model is used to conduct a comprehensive optimum design of PBCFs for the down-scaled propeller. Besides the commonly used rectangular PBCFs, nine airfoils are investigated, due to their favorable lift-to-drag ratio and great potential of being effective PBCFs. The best performing profile, among the 10 shapes, is chosen as the PBCF for further optimization. Finally, the optimum design of the PBCFs for the propeller/rudder system is achieved. It was found to yield remarkable efficiency gains for the modern propeller/rudder system under both design and off-design operation conditions, mainly due to the suppressed hub vortex and partly due to the extra thrust. The yield strength analysis confirmed that the optimum design is feasible in practice and can be used in industrial vessels. The generalized criteria for the optimum design of PBCFs also benefit other propeller/rudder systems for cost-effective energy saving.

It is important to make predictions of cavitation-induced erosion risk on ship propellers in the design phase. Since a cavitation tunnel test on a propeller model coated by soft paint, that is, a standard experimental method for evaluating erosion risk, is costly and time-consuming, numerical methods are necessary for erosion risk predictions. DES is made for cavitating flows around the propeller with a numerically modelled hull wake at the inflow. After achieving a converged solution, an erosion risk index is computed in each cell connecting to the blade surface and accumulated over a propeller rotation. Cavitation simulations are made for two propellers designed for a single-screw ship, of which one showed an erosion indication and the other showed no indication after cavitation tunnel tests with soft paint coating. Three index formulations are compared with the experiment result. The high value region of Index 1 based on the potential energy density of collapsing bubbles corresponds better with the eroded spot indicated by partial and complete paint removals in the experiment than those of the other indices. The maximum value of Index 1 for the non-eroded propeller is lower by more than an order of magnitude than that for the eroded one, whereas the maximum values of the other indices are of the same order of magnitude for both propellers. The validation of Index 1 is in agreement with the criterion that the maximum index needs to be below 1,000 J/m3 for erosion-free propeller designs. The design evolution based on the erosion risk index and propulsive efficiency from CFD shows that it can be a practical tool for a quantitative evaluation of blade surface erosion risk in the propeller design phase.

A functionalized phosphorene/polypyrrole (FPPY) hybrid nanomaterial was prepared via a mechanochemical process and chemical oxidative polymerization. The polymerization of polypyrrole (PPY) on the surface of two-dimensional phosphorene was investigated in detail. The amide bond formation of the FPPY hybrid improved the interfacial interaction between the PPY and phosphorene. The specific capacitance of the FPPY was 411.5 F g−1, which was approximately four times that of pristine PPY (106 F g−1). Additionally, hybridization improved the structural stability of PPY, yielding a cycle stability 2 times higher than that of pristine PPY. To the best of our knowledge, this is the first report on the potential of phosphorene hybridized with conducting polymers for practical energy-storage applications.

The effect of phase transition and exfoliation time on electro-responsive behavior of black phosphorus is identified by introducing black phosphorus and phosphorene to electrorheological fluid. Black phosphorus is successfully fabricated by mechanical milling for phase transition from red phosphorus, and phosphorene is fabricated by ultrasonication of the prepared black phosphorus. The morphology, degree of phase transition, and electrical conductivity of black phosphorus and phosphorene are precisely controlled by modifying the duration of both milling and delamination. It can be corroborated from a comprehensive study that the electrical conductivity as well as morphology affect the electro-responsive behaviors of black phosphorus and phosphorene. To the best of our knowledge, this is the first report on the meticulous control of phase transition and the potential of both black phosphorus and phosphorene as candidate materials for lectrorheological fluids. This study may provide understanding of the electro-responsive characteristics of black phosphorus and phosphorene, broadening the perspective of electro-responsive smart fluids.

The non-viral delivery of genes into macrophages, known as hard-to-transfect cells, is a challenge. In this study, the microporation of a CpG-free and small plasmid (pCGfd-GFP) showed high transfection efficiency, sustainable transgene expression, and good cell viability in the transfections of Raw 264.7 and primary bone marrow-derived macrophages. The non-viral method using the pCGfd vector encoding anti-EGFR single-chain Fv fused with Fc (scFv-Fc) generated the macrophages secreting anti-EGFR scFv-Fc. These macrophages effectively phagocytized tumor cells expressing EGFR through the antibody-dependent mechanism, as was proved by experiments using EGFR-knockout tumor cells. Finally, peri-tumoral injections of anti-EGFR scFv-Fc-secreting macrophages were shown to inhibit tumor growth in the xenograft mouse model. [BMB Reports 2020; 53(8): 442-447].

As the feature size of semiconductor devices decreases, the resist layer with high etch resistance is required to achieve fine pattern transfer during lithography. Conventional resists (e.g., amorp...

In this study, we aimed to analyze patient mortality rate after non-operative treatment of hip fractures to determine the distribution of causes of death and to compare factors affecting mortality.Between January 2013 and March 2019, a total of 93 patients (17 males, 76 females; mean age: 86.0±7.4 years; range, 64 to 98 years) who had hip fractures and were treated non-operatively were analyzed retrospectively. Survival, date of death, and cause of death were collected and analyzed. Baseline demographics, pre-trauma ambulation, pre- and post-trauma residence status, American Society of Anesthesiologists Physical Status (ASA PS) classification, and Parker's mobility score were compared with one-year mortality rates.The mean follow-up of survivors was 16.1±11.9 (range, 6.3 to 79.6) months. The mean survival of non-survivors was 4.9±6.1 (range, 0.007 to 27.3) months. The 3-, 6-, 12-, and 24-month mortality rates were 40.9%, 53.3%, 74.4%, and 87.5%, respectively. Respiratory diseases (33.3%) and cardiovascular diseases (13.6%) were the main causes of death among the patients. There was no statistically significant difference between the patients' age, sex, fracture site, pre-trauma ambulation, pre- and post-trauma residence status, ASA PS classification, Parker's mobility score, and one-year mortality.A significant number of patients are still treated non-operatively after hip fractures, and they have a high mortality rate. Efforts and research are needed to reduce mortality and improve the quality of life.

A highly transparent and high-performance random-network single-walled carbon nanotubes (r-SWCNTs) transistor was successfully fabricated by using chemical vapor deposition-grown graphene source/drain (S/D) electrodes. The bottom-gate, bottom-contact geometry was selected for the graphene S/D contact r-SWCNT (Gr-SWCNT) transistor because of its enhanced gate modulation and good sustainability. A palladium S/D contact r-SWCNT (Pd-SWCNT) transistor with the same device geometry was also fabricated for a comparative study. The transmission line method demonstrated that the resistivity of graphene was small enough (∼0.95 Ω μm) to be used as S/D electrodes in a single transistor device, and the contact resistance of Gr-SWCNTs was much lower than that of Pd-SWCNTs. Particularly, the correlation between the applied gate voltage and the sheet resistance is strongly dependent on the r-SWCNT film density. The resulting Gr-SWCNT transistor exhibits high mobility and good on/off current ratio compared to the Pd-SWCNT transistor. The high charge injection originated from the ohmic contact behavior and dense r-SWCNT channel formation by the enhancement of selective wetting due to the surface energy matching between the r-SWCNT semiconductor and graphene S/D electrodes. Thus, this approach can encourage creating highly transparent and high-performance carbon-based field effect transistor.

In this study, based on three-dimensional (3D) framework architecture built-up with two-dimensional (2D) graphitic carbon such as graphene, we have prepared a mechanically robust polymer composite without exhibiting notable deterioration of electrical conductivity under mechanical deformation. In constructing 3D framework comprising of graphitic carbons, two sophisticated methodologies, direct formation of graphitic layers on metal foam by chemical vapor deposition (CVD), and lay-up of reduced graphene oxide (rGO) nanosheets on metal foam have been performed, respectively, and their sustainability of conductive performance under mechanical deformation has been comparatively examined in terms of electrical conductivity change by cyclic mechanical stress. The CVD-synthesized graphene (CGr) framework-embedded PDMS composite, which means a PDMS composite containing 3D graphene framework grown by CVD process, exhibited electrical conductivity of ∼5 S/m at graphene content of 1.0 wt%, which was ∼5 orders of magnitude higher than that of 3D rGO framework-embedded PDMS composite containing comparable loading of rGO. When subjected to repetitive mechanical stress, it was found that the superior conductivity performance of CGr framework over rGO framework was well retained, presumably due to the higher perfectness of graphitic layers, which would impart much longer electron transfer to the framework architecture of graphitic carbon nanosheets.

Vertically aligned TiO2/ZnO nanotube (NT) arrays were developed for application to photoanodes in mesoscopic solar cells. By a two-step anodic oxidation, vertically aligned TiO2 NT arrays with highly ordered surface structure were prepared, followed by deposition of a ZnO shell with a precisely controlled thickness using atomic layer deposition (ALD). When applied to a photoanode of dye-sensitized solar cells (DSSCs), the photovoltage is gradually enhanced as the ZnO shell thickness of the TiO2/ZnO NT electrodes is increased. Furtheremore, the electron lifetime in photoanodes is significantly enhanced due to the ZnO shell, which is examined by open-circuit voltage decay (OCVD) measurement. Photocurrent density-voltage (J-V) curves under the dark condition and OCVD spectra reveal that a negative shift in TiO2 conduction band potential and an energy barrier effect owing to the ZnO shell concurrently contribute to the enhancement of VOC and electron lifetime.

We report a facile approach for producing highly omnidirectional and frequency tunable antennas based on multilayer graphene/multi-walled carbon nanotube (MG/MWNTs) electrodes. The MG sheets are obtained by ball milling graphite, followed by sonication. Monopole patch antennas are prepared by screen printing the MG/MWNTs paste onto a polymer substrate. The resulting antennas show excellent performance due to the bridge effect of the MWNTs between well-dispersed adjacent MG layers, which increases the contact area between MG sheets along the horizontal and vertical axes. The antennas formed from the MG/MWNTs exhibit smaller return losses than the antennas formed from pristine graphite, as well as high radiation efficiency (∼44.9%). Moreover, the MG/MWNTs antennas require a relatively small quantity, which leads to low production costs. In addition, the dimensions of the antennas can be simply adjusted by controlling the screen printing mask or cutting with scissors to achieve frequency tunability. These results demonstrate the potential of these MG/MWNTs antennas for applications in wireless communications for ubiquitous sensor networks.

Metal-semiconductor junctions are indispensable in semiconductor devices, but they have recently become a major limiting factor precluding device performance improvement. Here, we report the modification of a metal/n-type Si Schottky contact barrier by the introduction of two-dimensional (2D) materials of either graphene or hexagonal boron nitride (h-BN) at the interface. We realized the lowest specific contact resistivities (ρc) of 3.30 nΩ cm2 (lightly doped n-type Si, ∼ 1015/cm3) and 1.47 nΩ cm2 (heavily doped n-type Si, ∼ 1021/cm3) via 2D material insertion are approaching the theoretical limit of 1.3 nΩ cm2. We demonstrated the role of the 2D materials at the interface in achieving a low ρc value by the following mechanisms: (a) 2D materials effectively form dipoles at the metal-2D material (M/2D) interface, thereby reducing the metal work function and changing the pinning point, and (b) the fully metalized M/2D system shifts the pinning point toward the Si conduction band, thus decreasing the Schottky barrier. As a result, the fully metalized M/2D system using atomically thin and well-defined 2D materials shows a significantly reduced ρc. The proposed 2D material insertion technique can be used to obtain extremely low contact resistivities in metal/n-type Si systems and will help to achieve major performance improvements in semiconductor technologies.

To the best of our knowledge, the study described herein is the first to demonstrate the use of amorphous Sn–Ni islets as an anode material for lithium-ion storage. The islets are prepared by co-electrodeposition (2 s). In general, amorphous Sn–metal alloys exhibit significantly improved cycling performances over those of crystalline alloys with similar compositions and morphologies. However, to date, no thermodynamically metastable amorphous phase has been found in Sn–Ni alloys of any composition. Here, we show that the amorphization of such alloys is possible by ensuring rapid co-electrodeposition, so as to prevent Sn and Ni from crystallizing. The resulting amorphous Sn–Ni alloy affords suppressed capacity degradation due to the preservation of its initial microislet-shaped particles and its structural integrity after cycling. This is primarily due to the volume changes in the amorphous phase being small. These findings indicate the potential of this newly developed amorphous Sn–Ni alloy to be used as an anode material for lithium-ion rechargeable batteries.

Multilevel data storage using resistive random access memory (RRAM) has attracted significant attention for addressing the challenges associated with the rapid advances in information technologies. However, it is still difficult to secure reliable multilevel resistive switching of RRAM due to the stochastic and multiple formation of conductive filaments (CFs). Herein, we demonstrate that a single CF, derived from selective oxidation by a structured Cu active electrode, can solve the reliability issue. High-quality pyramidal Cu electrodes with a sharp tip are prepared via the template-stripping method. Morphology-dependent surface energy facilitates the oxidation of Cu atoms at the tip rather than in other regions, and the tip-enhanced electric fields can accelerate the transport of the generated Cu ions. As a result, CF growth occurs mainly at the tip of the pyramidal electrode, which is confirmed by high-resolution electron microscopy and elemental analysis. The RRAM exhibits highly uniform and low forming voltages (the average forming voltage and its standard deviation for 20 pyramid-based RRAMs are 0.645 and 0.072 V, respectively). Moreover, all multilevel resistance states for the RRAMs are clearly distinguished and show narrow distributions within 1 order of magnitude, leading to reliable cell-to-cell performance for MLC operation.

The state-of-the-art of the Internet of things (IoT) and smart electronics demands advances in thin and flexible radio frequency (RF) antennas for wireless communication systems. So far, nanostructured materials such as metals, carbon nanotubes, graphene, MXene, and conducting polymers have been investigated due to their noteworthy electrical conductivity. However, most antennas based on metallic materials are thick, which limits their application in miniaturized and portable electronic devices. Herein, we report two-dimensional (2D) metallic niobium diselenide (NbSe

Molybdenum disulfide (MoS2) incorporated with a conducting polymer can be a promising nanomaterial for use as low-cost electrodes in supercapacitors. MoS2 nanosheets are generally prepared by the high-pressure hydrothermal method, which has a few drawbacks such as low exfoliation yield, safety issues, and long-time processing. Herein, we report a simple and effective method for the high-yield (~72.5%) preparation of a MoS2/polypyrrole (MPY) hybrid nanomaterial via sonochemical exfoliation of ground bulk MoS2 in a polar aprotic solvent and subsequent chemical oxidative polymerization of pyrrole (PY) onto the MoS2 nanosheets. The strong non-covalent Mo–N bonding lowers the interfacial resistance, and the morphology of polypyrrole (PPY) can be easily controlled by varying the PY content. The MPY hybrid nanomaterial exhibited a maximum surface conductivity of 991 S sq., which is very high compared to that of pristine MoS2 nanosheet (~3.6 × 10–7 S sq.). When used in supercapacitors, the specific capacitance of the hybrid nanomaterial is 312 F g–1. Thus, improved capacitance retention with increase in the scan rate and enhanced diffusion process during electrochemical reactions result in good supercapacitor performance, which is important for the mass production of energy-storage devices.

Developing high-performance carbon-based flexible supercapacitors is crucial for energy-storage systems with high stability and safety. Here we report a succinct method of fabricating polypyrrole (PPY) by chemical vapour deposition polymerization on flexible graphene substrate. The dependency of initiators such as FeCl3 and CuCl2 for the polymerization of pyrrole is elucidated as well. The morphological changes as well as doping concentrations of PPY affect the capacitive behaviours of the nanocomposites. In addition, an assistance of dopamine between PPY and graphene not only improves the uniformity of PPY layers, but also enhances the supercapacitor performance. These results demonstrate the potential for the wearable energy-storage devices application.

Mannosylphosphorylated glycans are found only in fungi, including yeast, and the elimination of mannosylphosphates from glycans is a prerequisite for yeast glyco-engineering to produce human-compatible glycoproteins. In Saccharomyces cerevisiae, MNN4 and MNN6 genes are known to play roles in mannosylphosphorylation, but disruption of these genes does not completely remove the mannosylphosphates in N-glycans. This study was performed to find unknown key gene(s) involved in N-glycan mannosylphosphorylation in S. cerevisiae. For this purpose, each of one MNN4 and five MNN6 homologous genes were deleted from the och1Δmnn1Δmnn4Δmnn6Δ strain, which lacks yeast-specific hyper-mannosylation and the immunogenic α(1,3)-mannose structure. N-glycan profile analysis of cell wall mannoproteins and a secretory recombinant protein produced in mutants showed that the MNN14 gene, an MNN4 paralog with unknown function, is essential for N-glycan mannosylphosphorylation. Double disruption of MNN4 and MNN14 genes was enough to eliminate N-glycan mannosylphosphorylation. Our results suggest that the S. cerevisiae och1Δmnn1Δmnn4Δmnn14Δ strain, in which all yeast-specific N-glycan structures including mannosylphosphorylation are abolished, may have promise as a useful platform for glyco-engineering to produce therapeutic glycoproteins with human-compatible N-glycans.

BACKGROUND Cervical epidural injection (CEI) is widely performed on patients with pain originating from the cervical spine. Studies have shown a good relationship between the optic nerve sheath diameter (ONSD) and the intracranial pressure (ICP). OBJECTIVE The aim of this study was to evaluate the changes in the ONSD as a non-invasive surrogate marker of ICP after CEI. STUDY DESIGN Prospective observational study. SETTING Hospital and ambulatory pain clinic. METHODS Twenty patients undergoing CEI at the C5-6 level were enrolled in this observational study. The CEIs were performed using a total of 14 mL of mixture volume via the interlaminar approach in the right lateral decubitus position. The ONSD through ultrasonography was measured in the initial supine position (T0, baseline), 30 seconds after the completion of CEI (T0.5), at 30-second intervals for 5 minutes (T0.5~T5), and at one-minute intervals for 5 minutes (T6~T10). RESULTS The values of the baseline ONSD (T0) in both eyes were 4.1 ± 0.4 mm. The ONSD significantly increased from T1 to T10 (P < 0.05) compared with T0. The maximum value of the ONSD was measured as 5.1 ± 0.4 mm at T4, and the mean difference between the baseline ONSD and its maximum value was 1.0 mm, which represented about 27%. There was no increase in ICP-related complications such as dizziness, headache, visual acuity, or retinal hemorrhage. LIMITATIONS This was an observational study without a control group. All patients were presumed to have no intracranial pathology. CONCLUSION The 14 mL CEI resulted in an increase in the ONSD by ultrasonography over time. The most critical increase in ONSD was observed 4 minutes after CEI, but this increase was not sustained. Further work is needed to confirm the effects of the speed and volume of the injection and of the position. REGISTRATION Registered in the Clinical Research Information Service of the Korea National Institute of Health, registration number: KCT0001487. Key words: Analgesic techniques, epidural block, intracranial pressure, optic nerve sheath diameter, ultrasonography Analgesic techniques, epidural block, intracranial pressure, optic nerve sheath diameter, ultrasonography.

Highly crumpled graphene-based three dimensional (3D) interconnected and hierarchically porous conducting networks were prepared for application as electrocatalytic counter electrode (CE) in dye-sensitized solar cells (DSSCs). Finely and hierarchically crumpled graphene was synthesized from Fe 2 O 3 /graphene oxide (GO) hybrids via a one-step chemical etching–reduction process with HI solution. The synthesized crumpled graphene exhibited not only 24 times higher specific surface area, but also superior dispersibility in aqueous solution compared to conventional reduced graphene oxide (rGO). Owing to its superior solution processability and comparable electrical conductivity, the crumpled graphene could be assembled into 3D interconnected films on the substrates simply by drop casting, without any binders. In addition, although the crumpled graphene was not modified by dopants or high-temperature annealing, it showed much higher electrocatalytic activity for the I − /I 3 − redox couple compared to that of rGO, which is mainly attributed to its significantly larger accessible surface area for electrochemical reduction. As a result, the DSSC containing the crumpled graphene CE exhibited 2.8 times enhanced conversion efficiency (η = 5.15%) compared to that containing a rGO electrode (η = 1.86%).

Background: Although herniated disc fragments may resolve spontaneously, the optimal treatment option for massive lumbar disc herniation (LDH) has not been determined. Objective: To evaluate the extent of reduction in the size of massive LDH on magnetic resonance imaging (MRI) and the pain relief effect of transforaminal epidural steroid injection (TFESI) during the study period. Study Design: Retrospective evaluation. Setting: Hospital and ambulatory pain clinic, Korea. Methods: After Institutional Review Board approval, we conducted a retrospective review of 28 patients who underwent at least 2 MRIs during the period from January 2012 to December 2014. The size of the herniated mass was determined from the ratio of the anterior-posterior diameter of the spinal canal (C-value) to the maximum anterior-posterior diameter of the herniated disc (H-value) on axial MRI (C-H ratio). We also analyzed visual analogue scale (VAS) scores at baseline (T0), 2 weeks after the first and second TFESI (T1, T2), and at the second follow-up MRI (T3). Results: The mean C-value was 18.3 ± 2.9 mm. The mean H-value changed from 10.4 ± 1.9 mm to 4.5 ± 2.7 mm, and the mean C-H ratio changed from 58 ± 1.0% to 24 ± 1.4% (P < 0.001). Twenty-four of 28 patients demonstrated a reduction in the size of the herniation, and the mean reduction rate of the C-H ratio was 59%. In 4 patients, the LDH had not resolved on MRI, but the symptoms had diminished to such an extent that surgery was not required. The mean VAS score had significantly decreased at T1 and showed a continued decrease at the time of the last follow-up (P < 0.001). Limitations: This is a retrospective study and only offers data for patients who chose not to undergo surgery. In addition, the timing of repeat MRI was not standardized. Conclusion: The majority of cases of massive LDH demonstrated resolution at variable points between 3 and 21 months. TFESI could provide effective pain relief for patients with massive LDH in the interval without severe neurologic deterioration. IRB approval: Kangdong Sacred Heart Hospital: IRB Number # 14-1-10 Key words: Lumbar disc herniation, magnetic resonance imaging, migration, regression, resorption, sequestration, transforaminal epidural steroid injection

We proposed a new scheme, controlling the crack formation by notch patterns, to fabricate self-isolated high-efficiency gallium arsenide (GaAs)-based solar cells on a silicon (Si) substrate. The notch patterns introduced into the Si substrate were found to successfully generate the crack-free areas of 2 mm × 2 mm size separated by the cracks for the 5.8-μm-thick GaAs layers on it. The individual solar cells on the crack-free areas were confirmed to be electrically isolated from one another by the well-defined crack array. The open-circuit voltage and the efficiency of the crack-free cell were improved to 0.87 V and 18.0%, respectively, from 0.78 V and 14.7% for the cell with 33.2 cm−1 of linear crack density.

Vitamin D has received considerable attention in recent years owing to the increasing evidence of its importance in muscle function and physical performance. The present study attempted to determine whether patients with low serum vitamin D levels had impairment in early functional outcomes following total knee arthroplasty (TKA). This was a prospective cohort study that included 92 patients. Patients were divided into two groups according to their vitamin D levels as assessed at the preoperative visit: (1) vitamin D-deficient group, serum 25-hydroxyvitamin D3 (25(OH)D) levels

Highly sensitive, wearable and wireless pressure sensor was successfully fabricated based on the zinc oxide (ZnO) nanoneedle/poly(vinylidene difluoride) (PVDF) hybrid film. The nanoneedle structure of ZnO with large aspect ratio and hexagonal vertical grown pyramid form could lower the elastic modulus of the hybrid film compared to the ZnO nanorod. Due to its high permittivity, low polarization response time and outstanding durability, the hybrid film can be applied for a real-time pressure sensor to monitor the heart rate. Notably, the lowest detectable pressure of the hybrid film was as small as 4 Pa. Furthermore, the reduced graphene oxide (rGO) electrode-based Bluetooth antenna attained high peak gain (2.70 dBi) and radiation efficiency (78.38%), which was applicable to be used as an omnidirectional antenna to transmit wireless signal to the smart phone. Interestingly, the received wireless heart beat signal within a distance of 8 m was more sensitively measured on the radial artery than carotid artery without distortion and time delay, and it had a similar oscillation in comparison with the wire pressure sensor. This approach offers a valuable and promising tool for producing the commercial and continuous wireless pressure sensor for use in routine biomedical research and critical healthcare.

Roughness-induced resistivity variation of thin metal films is conveniently described by the Fuchs–Sondheimer model, where the phenomenological parameter p is used to quantify the extent of specular scattering at surfaces. However, p is a lumped parameter and does not include microscopic information that characterizes roughness, viz., auto-correlation function, root-mean-square height, and correlation length. In this work, we extract these roughness parameters for Cu films of thickness ranging from 31 nm to 95 nm. We find that the roughness–roughness correlation function is an exponential with a characteristic correlation length that increases monotonically with the film thickness. Using this, we predict the roughness parameter-dependent specularity coefficient, which has an implicit thickness dependency. This alters the resistivity scaling compared to the prevailing model of resistivity scaling, where p is assumed to be a constant.

Composite-based resistance switching random access memory (ReRAM) has great potential for application in flexible and wearable electronics. However, its large operating parameters and low reliability still have some limitations in realizing practical applications, which is derived from its high dependence on the orientation and dispersion of the filler in the composite layer. Here, we proposed a novel composite system that does not depend heavily on the orientation or dispersion of the fillers within the composite film of the ReRAM device. The AgNW/TiO2 core-shell nanowires inducing superb resistance switching behavior were fabricated. The composite resistance switching (RS) film was prepared by mixing the one-dimensional core-shell particles and poly (vinyl alcohol) (PVA) dielectric matrix. The composite RS film exhibited remarkable resistance switching behavior with extremely low/uniform operating voltage (Vset ~ 0.13 ± 0.013 V, and Vreset ~ −0.10 ± 0.012 V), and the reliable switching behavior was maintained for up to ~200,000 mechanical deformation cycles under 3 mm of bending radius. To evaluate the resistance switching mechanism of the composite-type ReRAM, the structural analysis and device modeling were performed.