Search

Although it is well known that photocatalytic titanium dioxide nanoparticles effectively decompose atmospheric nitrogen oxides (NOx), the long-term effects of the photocatalytic oxidation on the cementitious substrate have not been well explored. In this study, cement paste samples containing titanium dioxide nanoparticles were exposed to multiple cycles of nitrogen dioxide gas and ultraviolet radiation, along with wetting and drying, to simulate the effects of field exposure. The photocatalytic efficiency was monitored at each cycle and the surface of the samples was examined visually, chemically and mechanically between the cycles. The results indicate that the nitrogen dioxide oxidation efficiency decreased with cycling, possibly due to carbonation of the paste or loss of titanium dioxide particles. The pits found from the scanning electron microscopy images indicate there has been deterioration on the sample surfaces. Observations of surface deterioration imply possible acid attack, leaching and/or loss of titanium dioxide, suggesting that particularly the surfaces of cement-based materials can be negatively affected by photocatalysis.

A human can intuitively perceive and comprehend complicated tactile information, when interacting with objects, owing to the different cutaneous receptors distributed in the fingertip skin. Many research groups have attempted to mimic the structure and receptors of the skin to develop next-generation tactile sensors that can precisely and seamlessly deliver the overall tactile sensation. In this study, we propose a real-time multimodal tactile system that mimics the sensing qualities of cutaneous receptors entirely by simultaneously acquiring four types of decoupled tactile information in real time using multiple sensors integrated into three dimensions (3D), a signal-processing module, and a transmission module. The interconnections between 3D-integrated sensors and the signal-processing module were manufactured by 3D printing methods to have an adaptable shape. Furthermore, the proposed system can differentiate between various tactile stimuli, texture characteristics, and consecutive complex motions depending on the decoupled tactile sensing signals of pressure, shear force, vibration, and temperature. We believe that the results of this study can provide a novel design for a skin-like, perceivable, tactile sensing system for application in soft robotics, human-machine interfaces, health monitoring systems, and biomedical devices.

Flexible piezoelectric acoustic sensors (f-PAS) have attracted significant attention as a promising component for voice user interfaces (VUI) in the era of artificial intelligence of things (AIoT). The signal distortion issue of highly sensitive biomimetic f-PAS is one of the most challenging obstacle for real-life applications, due to the fundamental difference compared with the conventional microphones. Here, a noise-robust flexible piezoelectric acoustic sensor (NPAS) is demonstrated by designing the multi-resonant bands outside the noise dominant frequency range. Broad voice coverage up to 8 kHz is achieved by adopting an advanced piezoelectric membrane with the optimized polymer ratio. Deep learning-based speech processing of multi-channel NPAS is demonstrated to show the outstanding improvement in speaker recognition and speech enhancement compared to a commercial microphone. Finally, the NPAS independently identified the multi-user voices in a crowd condition, showing simultaneous speaker separation.

On-demand ride (ODR) services are expanding and becoming more influential globally because of the rapid growth in the use of mobile devices. ODR services are creating new business models and opportunities and reshaping transportation markets. This study used KakaoTaxi, a popular ODR service in Korea, to examine how customers evaluate an ODR service and determine whether customers are willing to reuse such a service. In the first-stage qualitative study, we explored decisional factors by conducting interviews with customers of the ODR service. In the second-stage quantitative study, we interpreted these previously explored decisional factors and developed a research model by applying the customer value theory. Going beyond previous research, the meta-inferences from the qualitative and quantitative studies explain how customers decide to reuse an ODR service. This study also informs ODR service providers of marketing strategies to leverage these key decisional factors in the reuse of an ODR service.

The concentration of n-alkanes (C17–C35) and sterols in marine particulate matter were investigated to trace the origin of organic carbon in Kongsfjorden in early spring (April). The spatial distributions of environmental factors (seawater temperature, salinity, density, turbidity, chlorophyll a (chl. a) and particulate organic carbon (POC) concentrations) and the cell density of phytoplankton differed between the inner and outer fjord regions. In addition, brassicasterol, diatom biomarker, showed a high concentration in the outer fjord and positive correlations with the chl. a and POC concentrations in the water column. In contrast, some sterols originating from terrestrial organic matter (OM), such as stigmasterol and campesterol, showed relatively higher concentrations in the inner fjord than in the outer fjord. Based on the distance-based redundancy analysis (db-RDA) result, the distributions of organic compounds are predominantly controlled by the water density and the POC and chl. a concentrations, and these distributions allowed us to divide the inner and outer fjord regions. However, the hierarchical clustering of principal components (HCPC) results obtained based on principal component analysis (PCA) using lipid biomarkers (C17–C35 alkanes and sterols) and environmental factors indicated that the clusters were distinguished by surface (0 m) and subsurface (>4 m) seawater samples rather than by any regional division. Notably, the concentration of relatively short-chain alkanes (average chain length (ACL): 24.6 ± 3.7) without a carbon preference for odd numbers (carbon preference index (CPI): 0.97 ± 0.11) in the sea surface layer was significantly higher than that of subsurface seawater (ACL: 31.1 ± 0.5 and CPI: 1.06 ± 0.03) in the early spring. This suggests the potential of these compounds as indicators for tidewater glacier-derived OM and freshwater input by snow melt into the fjord system. Hence, these results demonstrate that the distributions of lipid biomarkers in the water column possibly provide important information for a comprehensive understanding of the origin and transport of OM in an Arctic fjord.

Biomimetic piezoelectric mobile acoustic sensor is fabricated for exceptional accuracy of AI-based biometric authentication., Flexible resonant acoustic sensors have attracted substantial attention as an essential component for intuitive human-machine interaction (HMI) in the future voice user interface (VUI). Several researches have been reported by mimicking the basilar membrane but still have dimensional drawback due to limitation of controlling a multifrequency band and broadening resonant spectrum for full-cover phonetic frequencies. Here, highly sensitive piezoelectric mobile acoustic sensor (PMAS) is demonstrated by exploiting an ultrathin membrane for biomimetic frequency band control. Simulation results prove that resonant bandwidth of a piezoelectric film can be broadened by adopting a lead-zirconate-titanate (PZT) membrane on the ultrathin polymer to cover the entire voice spectrum. Machine learning–based biometric authentication is demonstrated by the integrated acoustic sensor module with an algorithm processor and customized Android app. Last, exceptional error rate reduction in speaker identification is achieved by a PMAS module with a small amount of training data, compared to a conventional microelectromechanical system microphone.

Background Subarachnoid hemorrhage is a potentially devastating cerebrovascular attack with a high proportion of poor outcomes and mortality. Recent studies have reported decreased mortality with the improvement in devices and techniques for treating ruptured aneurysms and neurocritical care. This study investigated the relationship between hospital volume and short- and long-term mortality in patients treated with subarachnoid hemorrhage. Methods We selected subarachnoid hemorrhage patients treated with clipping and coiling from March–May 2013 to June–August 2014 using data from Acute Stroke Registry, and the selected subarachnoid hemorrhage (SAH) patients were tracked in connection with data of Health Insurance Review and Assessment Service to evaluate the short-term and long-term mortality. Results A total of 625 subarachnoid hemorrhage patients were admitted to high-volume hospitals (n = 355, 57%) and low-volume hospitals (n = 270, 43%) for six months. The mortality of SAH patients treated with clipping and coiling was 12.3%, 20.2%, 21.4%, and 24.3% at 14 days, three months, one year, and five years, respectively. The short-term and long-term mortality in high-volume hospitals was significantly lower than that in low-volume hospitals. On Cox regression analysis of death in patients with severe clinical status, low-volume hospitals had significantly higher mortality than high-volume hospitals during short-term follow-up. On Cox regression analysis in the mild clinical status group, there was no statistical difference between high-volume hospitals and low-volume hospitals. Conclusion In subarachnoid hemorrhage patients treated with clipping and coiling, low-volume hospitals had higher short-term mortality than high-volume hospitals. These results from a nationwide database imply that acute SAH should be treated by a skilled neurosurgeon with adequate facilities in a high-volume hospital., Graphical Abstract

We developed a novel concept of a highly efficient, transparent, and flexible triboelectric nanogenerator (TF-TENG) based on a metallic nanowire-embedded conducting polymer as a contact electrode. In contrast to metals that are highly tribopositive but opaque and less flexible, a conducting polymer, poly(3,4-ethylenedioxythiophene): poly(styrene sulfonate) (PEDOT:PSS), is transparent, flexible, and shows moderately high tribonegativity which is capable of accepting the electrons from the counter surface in the TF-TENG during contact. The silver nanowire layer placed beneath the conducting polymer layer results in the increase of the conductivity and the surface roughness as well. The output voltage was about 160 V. The output current (> 50 µA) was at least five times larger than any of existing TF-TENGs and a substantially high value of the instantaneous power density (> 1.5 mW/cm2) was obtained. Using such TF-TENG, a self-powered system for instantaneous touch visualization was demonstrated using a liquid crystal device. Our TF-TENG, built on a stretchable substrate, exhibits high transparency and excellent output performance on an arbitrary surface like a human skin or a fabric so that it enables to devise a variety of power sources for flexible and transparent electronics.

Cytotherapy with mesenchymal stem cells (MSCs) has been studied in many species, and often requires in vitro cell expansion to obtain therapeutic doses of stem cells. Because the characteristics of MSCs, such as self-renewal and multi-lineage differentiation, can be altered by long-term culture, it is important to maintain stemness during cultivation. This study assessed the changes in the characteristics of feline adipose tissue-derived (fAT)-MSCs during in vitro passaging. Stem cells isolated from the adipose tissue of donor cats were cultured for seven sub-passages. Proliferation capacity was analyzed by calculating the cell doubling time and by colorimetric assay. Expression of stem cell-specific markers was evaluated by quantitative reverse transcription (qRT)-PCR and immunophenotyping. Expression of adipogenic and osteogenic differentiation markers was also measured by qRT-PCR. Histochemical staining and measurement of β-galactosidase activity were conducted to detect cellular senescence. The cell proliferation rate decreased significantly at passage 5 (P5). Gene expression levels of pluripotency markers (Sox2, Nanog and Klf4) and stem cell surface markers (CD9, CD44, CD90 and CD105) decreased during continuous culture; in most assays, statistically significant changes were observed at P5. The ability of cells to undergo adipogenic or osteogenic differentiation was inversely proportional to the number of passages. The proportion of senescent cells increased with the number of passages. These results suggest that repeated passages alter the proliferation and multipotency of fAT-MSCs. In clinical trials, early-passage cells should be used to achieve the maximum therapeutic effect.

Mesenchymal stem cells (MSCs) have immunomodulatory functions and differentiation capacity, and their clinical use is increasing in veterinary species. Although MSCs have been applied in the treatment in various inflammatory diseases, mechanistic research on feline MSCs is lacking. Accordingly, in this study, we aimed to investigate the immunomodulatory mechanisms of MSCs isolated from feline adipose tissue (fATMSCs). fATMSCs from healthy cats were cultured in an appropriate manner and cocultured with transwell-separated allogeneic feline peripheral blood mononuclear cells (fPBMCs) and RAW264.7 murine macrophages. After 48h of coculture, RNA was extracted from RAW264.7 cells and fPBMCs. Cytokine expression in these cells was measured using quantitative real-time polymerase chain reaction (qRT-PCR) and compared according to the presence of fATMSCs. The mRNA levels of pro-inflammatory cytokines, e.g., tumor necrosis factor-α (TNF-α), inducible nitric oxide synthase, and interleukin (IL)-1β, were significantly decreased in cocultures of mitogen-stimulated RAW264.7 cells with fATMSCs compared with that in the RAW264.7 cells control group. Additionally, changes in the expression of mRNAs extracted from fPBMCs were as follows: pro-inflammatory TNF-α, interferon-γ, and IL-6 were decreased, and anti-inflammatory IL-10 was increased during coculture of mitogen-stimulated allogeneic fPBMCs with fATMSCs. We also extracted RNA and collected supernatants from fATMSCs during transwell culture for measurement of the expression and secretion of soluble factors by qRT-PCR and enzyme-linked immunosorbent assays, respectively. The mRNA expression of immunomodulatory factors from fATMSCs, including cyclooxygenase-2 (COX-2), transforming growth factor (TGF)-β, indoleamine-2,3-dioxygenase (IDO) and hepatocyte growth factor, increased in the presence of RAW264.7 cells. Similarly, TGF-β, COX-2, and IDO mRNA expression and prostaglandin E2 (PGE2) secretion from fATMSCs increased in the presence of allogeneic fPBMCs. Finally, we measured the viability of fPBMCs under various conditions. Cell viability decreased in fPBMCs suspended in fATMSC-derived conditioned medium, and this reduction was alleviated in the group supplemented with NS-398 a PGE2 inhibitor. Our data suggested that soluble factors, including PGE2, secreted by fATMSCs played an important role in the immunomodulatory effects of these cells. These findings may be helpful in the application of fATMSCs to feline patients with immune-related diseases.

In this study, the influence of pore structure on the extent of calcium nitrate salt crystallization damage on mortar samples was examined. The pore volume and structure was altered by varying water-to-binder ratio and by adding nanoparticles. The results show that calcium nitrate salt exposure induces cracking in mortar samples and that more damage was observed at higher water-to-binder ratio and higher rate of nanoparticle use. It is proposed that the refined pore structure induced by nanoparticle use can result higher salt crystallizing pressure. Thus, cementitious structures that are expected to be exposed to salt crystallization should be designed to meet strength needs by lowering water-to-binder ratio

A microarray of conducting polymer electrodes with high resolution and high pattern-fidelity is developed on a stretchable substrate through the directed wetting localization (DWL) by the differential hydrophobicity. The large difference in the surface energy between the wetting and dewetting regions serves as the major determinant of the pattern resolution and the pattern-fidelity, yielding the full surface coverage in the stretchable electrode array (SEA) with 30 μm in width. The electrical characteristics of the SEA are well preserved under different types of elastic deformations. All-solution-processed polymer light-emitting diodes (except for the cathode) based on our patterned stretchable electrodes show no appreciable degradation of the performance under stretching. The DWL provides a simple and effective way of building up diverse stretchable electrical and optoelectronic devices in advanced wearable and bio-integrated electronics.

Mechanical energy harvesting technology converting mechanical energy wasted in our surroundings to electrical energy has been regarded as one of the critical technologies for self-powered sensor network and Internet of Things (IoT). Although triboelectric energy harvesters based on contact electrification have attracted considerable attention due to their various advantages compared to other technologies, a further improvement of the output performance is still required for practical applications in next-generation IoT devices. In recent years, numerous studies have been carried out to enhance the output power of triboelectric energy harvesters. The previous research approaches for enhancing the triboelectric charges can be classified into three categories: i) materials type, ii) device structure, and iii) surface modification. In this review article, we focus on various mechanisms and methods through the surface modification beyond the limitations of structural parameters and materials, such as surficial texturing/patterning, functionalization, dielectric engineering, surface charge doping and 2D material processing. This perspective study is a cornerstone for establishing next-generation energy applications consisting of triboelectric energy harvesters from portable devices to power industries., Graphical abstract

We developed a low-cost flexible pressure sensor based on an elastomer film with uniformly distributed micro-pores as a dielectric layer. The dispersion of the micro-pores in the elastomer film results from the phase separation between a prepolymer material and deionized water to the elastomer, followed by the subsequent evaporation of the solvent within the polymer matrix after polymerization. Owing to the enhanced deformability by the pore structures, the relatively high sensitivity of 1.18 kPa−1 in the low pressure (

After a piezoelectric inkjet printhead jets the first droplet, the actuating membrane still vibrates, creating residual vibrations in the ink channel, which can degrade the inkjet printhead performance. For suppressing these vibrations, an optimized actuating voltage waveform with two pulses must be obtained, of which the first pulse is used for jetting and the second pulse is used to suppress the residual vibrations. In this study, the pressure history within the ink channel of a recirculating piezoelectric inkjet printhead was first acquired using lumped element modeling. Then, for suppressing residual vibrations, a bipolar voltage waveform was optimized via analysis of the tuning time (tt ), dwell time (td2), rising time (tr2), falling time (tf2), and voltage amplitude of the second pulse. Two voltage waveforms, Waveform 01 and Waveform 02, were optimized thereafter. In Waveform 01, tt=2 μs, td2=2 μs, and tr2 and tf2=1 μs were finalized as the optimal parameters, in the case of another waveform, the optimal parameters of td2, tr2, and tf2 were found to be 4, 1, and 1 μs, respectively. The optimal voltage amplitude of the second pulse was found to be 1/3 the amplitude of the first pulse. On the basis of our analysis, the tuning time in Waveform 01 is the most sensitive parameter, and the performance yielded is even poorer than that yielded by standard waveform, if not optimized. Therefore, the other waveform is recommended for the suppression of residual vibrations.

A new concept of intensity-tunable structural coloration is proposed on the basis of a helical photonic crystal (HPC). The HPCs are constructed from a mixture of chiral reactive mesogens by spin-coating, followed by the photo-polymerization. A liquid crystal (LC) layer, being homogeneously aligned, is prepared on the HPCs to serve as a tunable waveplate. The electrical modulation of the phase retardation through the LC layer directly leads to the intensity-tunable Bragg reflection from the HPCs upon the incidence of the polarized light. The bandwidths of the structural colors are found to be well preserved regardless of the applied voltage. A prototype of a full color reflective-type display, incorporated with three primary color units, is demonstrated. Our concept of decoupling two mutually independent functions, the intensity modulation by the tunable waveplate and the color reflection by the HPCs provides a simple and powerful way of producing a full color reflective-type display which possesses high color purity, high optical efficiency, the cycling durability, and the design flexibility.

Cytotherapy with mesenchymal stem cells (MSCs) has been studied in many species, and often requires in vitro cell expansion to obtain therapeutic doses of stem cells. Because the characteristics of MSCs, such as self-renewal and multi-lineage differentiation, can be altered by long-term culture, it is important to maintain stemness during cultivation. This study assessed the changes in the characteristics of feline adipose tissue-derived (fAT)-MSCs during in vitro passaging. Stem cells isolated from the adipose tissue of donor cats were cultured for seven sub-passages. Proliferation capacity was analyzed by calculating the cell doubling time and by colorimetric assay. Expression of stem cell-specific markers was evaluated by quantitative reverse transcription (qRT)-PCR and immunophenotyping. Expression of adipogenic and osteogenic differentiation markers was also measured by qRT-PCR. Histochemical staining and measurement of β-galactosidase activity were conducted to detect cellular senescence. The cell proliferation rate decreased significantly at passage 5 (P5). Gene expression levels of pluripotency markers (Sox2, Nanog and Klf4) and stem cell surface markers (CD9, CD44, CD90 and CD105) decreased during continuous culture; in most assays, statistically significant changes were observed at P5. The ability of cells to undergo adipogenic or osteogenic differentiation was inversely proportional to the number of passages. The proportion of senescent cells increased with the number of passages. These results suggest that repeated passages alter the proliferation and multipotency of fAT-MSCs. In clinical trials, early-passage cells should be used to achieve the maximum therapeutic effect.

Colloidal microwires are constructed using anisotropic assembling templates with periodically wrinkled patterns of a liquid crystalline polymer (LCP). The wrinkled LCP patterns with the period of a...

Demonstrated herein is a liquid-crystal-(LC)-based lenticular lens array with a polarization-dependent focusing effect, fabricated through a simple imprinting process. The input polarization dependence of the proposed LC lenticular lens array arises mainly from the index matching scheme between the polymer lenticular lens and the LC on it. For the input polarization perpendicular to the LC director, the focal length of the lenticular lens is about 3.1 mm. The focusing and non-focusing properties depending on the input polarization are useful for realizing autostereoscopic 2D/3D convertible displays combined with polarization selection elements.

The present study was designed to evaluate the effect of SB injection, which is composed of extracts from the roots of Pulsatilla koreana, Panax ginseng, and Glycyrrhiza glabra, on the viability of canine osteosarcoma and melanoma cells and nonneoplastic canine cells. Cells were treated with SB injection, conventional chemotherapeutic drugs, or a combination of both at various concentrations. Cellular viability was evaluated using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Flow cytometry was used to evaluate the cell cycle and apoptosis. SB injection inhibited the growth of osteosarcoma and melanoma cells in a dose-dependent manner. The cell cycle of the affected cells was arrested in the G2/M phase, indicating an anti-proliferative effect. SB injection dose-dependently increased the rate of apoptosis. Furthermore, we found that combining SB injection with chemotherapeutic drugs resulted in a greater reduction in canine malignant cell proliferation than either treatment alone. SB injection did not affect the viability of peripheral blood mononuclear cells regardless of concentration, which suggested that SB injection did not suppress the activity of normal cells. This study suggested that SB injection can be considered an effective alternative medication for animal cancers in veterinary medicine.

Photocatalytic cement has been receiving attention due to its high oxidation power that reduces nitrogen oxide, thus contributing to a clean atmospheric environment. However, there has not yet been a thorough investigation on the effect of photocatalytic reactions on the durability of cementitious material, the parent material. In this study, photocatalytic cement samples were exposed to nitric oxide gas and UV along with cycles of wetting and drying to simulate environmental conditions. The surface of samples was characterized mechanically, chemically, and visually during the cycling. The results indicate that that the photocatalytic efficiency decreased with continued NO oxidation. The pits found from SEM indicated that chemical deterioration, such as acid attack or leaching, did occur. However, this was not confirmed by X-ray diffraction. The hardness was not affected, probably due to the formation of CSH as evidenced by the XRD pattern. In conclusion, it was found that photocatalysis could alter cementitious materials both chemically and mechanically, which could further affect long-term durability.

The photocatalytic oxidation and binding capacity of cement containing titanium dioxide nanoparticles under nitric oxide and nitrogen dioxide gas exposures were examined experimentally both in the presence and absence of ultraviolet (UV) light, to examine independently the contributions of photocatalysis and potential additional mechanisms for binding of nitrogen oxides (NOx) inherent in cement-based materials. The overall, photocatalytic efficiency was similar for both gas exposures, with faster initial rates of initial NO binding for higher water-to-cement ratio pastes, due to higher surface area. In the absence of UV light, greater binding of NO2 gas was found compared to NO gas, perhaps due to the greater polarity of the NO2 molecule, although further examination of this phenomenon is warranted. Overall, these experiments show not only the fact that cementitious materials can be tailored to decrease NOx levels through photocatalysis but also the fact that Portland cements possess the inherent ability to bind NOx, and in particular NO2.

We present the photonic printing that can display different color images depending on the optical polarization of incident light. The dynamic selection among different images becomes possible by using anisotropic Fabry-Perot resonators that incorporate a layer of liquid crystal molecules aligned by directional molecular registration (DMR) as polarization-dependent color pixels. Using the new device platform, we demonstrate a prototype of an anticounterfeiting label with inherent anti-replicability that results from the molecular-level origin of security images. In addition, this concept is extended to polarization-selective holography. Our molecular-level approach enables to develop a new class of security labels and holographic storage media.

Water supply facilities such as waterworks systems are facilities that supply residential and industrial water essential for humans to live and it is essential for these facilities to be prepared for earthquake hazards. In the present study, new hydraulic analysis procedures that can complement problems in existing model were proposed for performance quantification under seismic hazards. Detailed procedures for estimating the serviceability of water supply networks using pressure dependent demand (PDD) and pressure dependent leakage (PDL) techniques were proposed. The developed methodologies can simulate many pipe leakage and breakage situations more realistically. The methodologies were applied to representative pipe networks to investigate the models and new performance quantification indicators were additionally presented. The developed models are judged to be usable as a basic tool finding for guidelines because they can simultaneously quantify the amount of leakage calculated from the viewpoint of suppliers as well as the water availability of consumers when an earthquake hazard has occurred.

The effect of titanium dioxide (TiO2) nanoparticles on early age and long-term properties of cement-based materials is examined experimentally through isothermal calorimetry, chemical shrinkage, setting time, compressive strength and surface microhardness, where part of the cement is replaced with TiO2. Early age hydration is accelerated by TiO2 nanoparticles which also increase degrees of hydration of Portland cement, as evidenced by isothermal calorimetry and chemical shrinkage results. With increasing amounts of TiO2, setting time is reduced, despite decreasing cement content, due to TiO2 replacement, again showing accelerated hydration. Comparing TiO2–cement composites from two different TiO2 manufacturers, results suggest that size of nanoparticles and dispersability are critical in the rate of hydration, with smaller size agglomerates, but not necessarily smaller size particles, producing a greater effect. Compressive strength increases with higher TiO2 nanoparticle replacement at lower water-to-solids ratio (w/s = 0·40) and strength is not compromised by up to 10% TiO2 replacement at higher w/s = 0·60. However, microhardness of the composite decreases with higher TiO2 amount. Broadly, these results indicate that mineral addition as cement replacement can be optimised in terms of dosage and dispersability to achieve lower cement fractions without compromising strength, but that the potential for reductions in hardness should be considered.

The use of nano-sized particles in cementitious materials introduces a myriad of potential innovations from new functionality to enhanced mechanical performance, but such materials can be energy-intensive to manufacture. With increasing emphasis on sustainable development, it is important to investigate and understand benefits and costs of using nanomaterials compared to relatively less energy-intensive microparticles. The current research investigates the effect of chemically inert nano and microparticles (i.e., titanium dioxide (TiO 2 ) and calcium carbonate (limestone)) on early age properties and behavior of cement-based materials. Results indicate that the early age hydration rates, shrinkage, and pore structure of cement-based materials can be modified and optimized by tailoring the size of fillers. Life cycle analysis indicates that photocatalytic reactivity of TiO 2 could offset initial higher environmental impacts. Thus, optimally sized nanoparticles could revolutionize the construction industry by allowing tailoring of structure and properties of cement-based composites, with environmental sustainability preserved through the selection of lower embodied-energy particles.

A simply modified biosensor based on protein A-modified distributed Bragg reflectors (DBR) porous silicon (PSi) chip for the detection of human immunoglobin G (IgG) are developed. The fabrication, optical characterization, and surface derivatization of DBR PSi are investigated. The sensor system studied consist of multi-layer of porous silicon modified with protein-A. The sensor is operated by the measurement of the reflection peak in the white light reflection spectrum. Molecular binding is detected as a shift in wavelength of reflection peaks.

Photoluminescence properties and surface morphologies of porous silicon were investigated by controlling of etching times and applied current densities. FE-SEM image of porous silicon surface indicated that the porous silicon prepared at currents below 200mA/cm^2 exhibited very stable and even surface. However the porous silicon prepared at currents above 300mA/cm^2 displayed the cracked surface of porous silicon. This cracked surface was collapsed to give cracked domains at currents over 500mA/cm^2. Photoluminescence of porous silicon was investigated by controlling of etching times and applied current densities in the range from 50 to 900s and from 50 to 800mA/cm^2, respectively. Photoluminescence intensity of porous silicon increased gradually during etching process, reached maximum, and then decreased as the etching time increased. Porous silicon showed the best photoluminescence efficiency was prepared at currents of 200mA/cm^2 and etching time of 300s.

The effect of chemically inert nanoparticles of anatase titanium dioxide (TiO2) on hydration rate of belite (β-C2S) was studied using isothermal calorimetry. The TiO2 was added to β-C2S paste at 0%, 5%, and 10% by mass. The results indicate that the addition of TiO2 nanoparticles shorten the induction period and accelerate hydration beyond 3 days, showing rate peaks at 40 days of age. The cumulative heat data suggests that TiO2-containing C2S pastes increase in degree of hydration at 90 days by 47% compared to neat C2S pastes. These results suggest that addition of inert nanoparticles could potentially promote earlier strength gain of C2S in cement, ameliorating a perceived deficiency in cement compositions which could contribute to sustainability in terms of lower CO2 emissions and lower energy use compared to traditional chemistries.

Single-port laparoscopic-assisted vaginal hysterectomy (S-LAVH) uses only one transumbilical incision site and has better cosmetic result than conventional multiport LAVH. This study aimed to evaluate our initial experience with S-LAVH compared with the more conventional three-port LAVH in women with benign uterine diseases.Between April 2009 and April 2010, S-LAVH was attempted on 183 patients with benign uterine diseases through a transumbilical incision for a 12-mm trocar, and conventional LAVH was performed on 275 patients by the same surgeon. The medical records of patients were reviewed. The age, body mass index, operative time, blood loss, and uterine weight on pathologic report were compared.Two of 183 patients in the S-LAVH group were converted to two- or three-port surgery, compared with none in the conventional group. Data analysis was done for 181 patients in the S-LAVH group and 275 patients in the conventional LAVH group. No major complications, including ureteral or bladder injuries, occurred in any of the patients. No statistically significant differences were found in mean age, mean body mass index, mean operative time, mean anesthesia time, mean estimated blood loss, or mean postoperative days to passage of flatus, but the mean uterine weights on the pathologic reports were significantly reduced in the S-LAVH group.S-LAVH could be a feasible alternative method for removal of the uterus with a better cosmetic outcome resulting from single wound in selected patients. For patients with large-sized uterus, more surgical experience and improvement in instruments suitable for S-LAVH are needed.

Background As intravenous thrombolysis (IVT) has very restricted inclusion criteria, eligible patients of IVT constitute a very small proportion and studies about their mortality are rare. The long-term mortality in a patients with contraindication of ineligible patients of IVT still under the debate. So, we investigated the proportion of patients with contraindication of IVT and the short and long-term mortality of them in AIS on emergency department comparing with the long-term effect of IVT in patients with moderate-to-severe stroke. Methods Using acute stroke assessment indication registry & Health Insurance Review and Assessment Service database, a total of 5,407 patients with NIHSS≥5 were selected from a total of 169 acute stroke care hospital nationwide during October-December 2011 and March-June 2013. We divided AIS patients into two groups: 1) IVT group who received IVT within 4.5 hours, and 2) non-IVT group who did not receive the IVT because of contraindications. And we divided the subgroups according to the reason of contraindication of IVT. The 5-year survival rate of each group was assessed using Kaplan-Meyer survival analysis. Results Of the 5,407 patients, a total of 1,027 (19%) patients who received IVT using r-tPA within 4.5 h after onset. Compared with the IVT group, hazard ratios of non-IVT group were 1.33 at 3 months, 1.53 at 1 year and 1.47 at 5 years (p

Supplemental Digital Content is available in the text, This study aimed to investigate the association between volume of surgery and mortality in relation to interventions for acute hemorrhagic stroke, namely craniotomy and trephination. We obtained data on acute hemorrhagic stroke patients for a 5-year period (2009–2013) from the Health Insurance Review and Assessment Service. Hospitals were classified into 3 categories according to volume of surgery (low, medium, high). To avoid intentionally setting a cutoff, we placed the hospitals in order from those with high volume of surgery to those with low volume of surgery and divided them into 3 groups (tertile) according to the number of patients. The covariates were age, sex, hemorrhagic stroke site, type of health insurance, intensive care unit admission, history of hypertension, and Charlson comorbidity index. Multiple logistic regression analysis was performed with statistical significance set at 5%. A total of 41,917 patients who underwent craniotomy (n = 20,982) or trephination (n = 20,935) for acute hemorrhagic stroke were analyzed according to hemorrhage site (subarachnoid and others). The results showed that mortality from acute hemorrhagic stroke decreased with increasing volume of surgery. For subarachnoid hemorrhage, the odds ratios of the medium- and high-volume surgery groups were significantly lower (0.74 and 0.59, respectively) for mortality within 7 days of admission, and were also significantly lower (0.78 and 0.68) for mortality within 30 days of admission than that of the low-volume surgery group. The results for other hemorrhage sites were similar. The association between mortality and volume of surgery was more evident in the craniotomy group. Although this study was limited to a single country (South Korea), it partially addressed the shortcomings of previous studies by analyzing a nationwide database and examining all types of hemorrhagic strokes.

The effect of nanoanatase titanium dioxide (TiO2) powder on early-age hydration kinetics of tricalcium silicate (C3S) was investigated. Isothermal calorimetry was performed on C3S pastes with 0%, 5%, 10%, and 15% of TiO2 addition by weight, and two mathematical models—the Avrami (or JMAK) model and the boundary nucleation model (BN model)—were fitted to the data. For all of the mixes, the addition of TiO2 increased the peak reaction rate, and increased the degree of hydration at 12 and 24 h. The rate of hydration of 10% and 15% TiO2 pastes were accelerated, while the 5% TiO2 paste was delayed, lengthening the induction period as compared with the control paste. The model fits demonstrate that the BN model captures the kinetics of the reaction better, particularly in the deceleration period, than the Avrami model. This is related to the ratio of rate parameters (kB/kG) of the BN model, that the increasing ratio gives a more unsymmetrical shape of a rate curve. The increase in kB/kG with TiO2 addition at 5%, 10%, and 15% suggests that hydration product is formed on or near the surfaces of TiO2 particles, as well as on the C3S surface. These results demonstrate that the addition of TiO2 nanoparticles accelerates the early hydration by providing additional nucleation sites, forming the foundation for future optimization of photocatalytic and other nanoparticle-containing cements.

The performance and properties of cement-based materials can potentially be altered by the addition of nano-sized inclusions. In this study, the effect of chemically nonreactive anatase TiO2 nanoparticles on early-age hydration of cement was investigated. First, the effects of different percentage addition rates of TiO2 to portland cement on early-age behavior were examined through isothermal calorimetry and measurements of chemical shrinkage. On the basis of accelerations in hydration observed in TiO2 portland cements, additional experiments were performed with tricalcium silicate (C3S), the main strength-giving mineral component of portland cement, to determine whether the influence of TiO2 could be adequately described by a kinetic model that relies on boundary nucleation theory. Comparison of the experimental results and the modeling showed that (a) an increase in addition rates of TiO2 accelerates the rate of cement hydration and (b) the heterogeneous nucleation effect rather than the dilution effect was dominant. The result of the boundary nucleation model reinforces the concept of the heterogeneous nucleation effect and demonstrates that the surface area provided by nano-TiO2 particles increases the rate of hydration reaction. This research forms the foundation for future studies aimed at optimizing photocatalytic and other nanoparticle-containing cements.