Search

Forecasting solar irradiance is of utmost importance in supplying renewable energy efficiently and timely. This paper aims to experiment five variants of recurrent neural networks (RNN), and develop effective and reliable 5-minute short term solar irradiance prediction models. The 5 RNN classes are long-short term memory (LSTM), gated recurrent unit (GRU), Simple RNN, bidirectional LSTM (Bi-LSTM), and bidirectional GRU (Bi-GRU); the first 3 classes are unidirectional and the last two are bidirectional RNN models. The 26 months data under consideration, exhibits extremely volatile weather conditions in Jinju city, South Korea. Therefore, after different experimental processes, 5 hyper-parameters were selected for each model cautiously. In each model, different levels of depth and width were tested; moreover, a 9-fold cross validation was applied to distinguish them against high variability in the seasonal time-series dataset. Generally the deeper architectures of the aforementioned models had significant outcomes; meanwhile, the Bi-LSTM and Bi-GRU provided more accurate predictions as compared to the unidirectional ones. The Bi-GRU model provided the lowest RMSE and highest R2 values of 46.1 and 0.958; additionally, it required 5.25*10-5 seconds per trainable parameter per epoch, the lowest incurred computational cost among the mentioned models. All 5 models performed differently over the four seasons in the 9-fold cross validation test. On average, the bidirectional RNNs and the simple RNN model showed high robustness with less data and high temporal data variability; although, the stronger architectures of the bidirectional models, deems their results more reliable.

Si-doped Fe-rich compounds, i.e., Sm(Fe0.8Co0.2)11Ti + Six (x = 0, 0.5, and 1.0), with ThMn12-type structure in forms of ribbons and bulks were fabricated using melt-spinning process and high pressure pressing and heat treatment processes. Physical and magnetic properties of the ribbons and bulks were analyzed to investigate Si doping effects on the Sm(Fe0.8Co0.2)11Ti. The Si-free ribbons were found to be amorphous, while the small amount of Si doping resulted in dramatic crystallization of the ThMn12 phase. Coercivity of the ribbons increased with the increasing Si content from 43 to 3140 Oe, while the magnetization decreased from 146 to 78 emu/g. It was observed that the Si-free ribbons consisted of nano-sized grains in the matrix of an amorphous phase. On the other hand, the Si-doped ribbons exhibited submicron-sized grains with high crystallinity. The crystallized phases of the heat-treated bulks varied with the Si concentrations; the main phase was the ThMn12 phase in all samples, but concentrations of soft magnetic α-Fe phase decreased with the increasing Si concentration, and corresponding saturation magnetizations of the bulks also decreased.

Background Despite the lack of official COVID-19 statistics, various workplaces and occupations have been at the center of COVID-19 outbreaks. We aimed to compare legal measures and governance established for managing COVID-19 infection risks at workplaces in nine Asia and Pacific countries and to recommend key administrative measures. Methods We collected information on legal measures and governance from both general citizens and workers regarding infection risks such as COVID-19 from industrial hygiene professionals in nine countries (Indonesia, India, Japan, Malaysia, New Zealand, Republic of the Philippines, Republic of Korea, Taiwan, and Thailand) using a structured questionnaire. Results A governmental body overseeing public health and welfare was in charge of containing the spread and occurrence of infectious diseases under an infectious disease control and prevention act or another special act, although the name of the pertinent organizations and legislation vary among countries. Unlike in the case of other traditional hazards, there have been no specific articles or clauses describing the means of mitigating virus risk in the workplace that are legally required of employers, making it difficult to define the responsibilities of the employer. Each country maintains own legal systems regarding access to the duration, administration, and financing of paid sick leave. Many workers may not have access to paid sick leave even if it is legally guaranteed. Conclusion Specific legal measures to manage infectious disease risks, such as providing proper personal protective equipment, education, engineering control measures, and paid sick leave are recommended to be stipulated in Industrial safety and health-related acts.

High density sintered Sm(Fe0.8Co0.2)11Ti bulk magnets were successfully produced using a newly developed high pressure pressing fabrication method. The purity of the hard magnetic ThMn12 phase in the bulk magnet reached to higher than 97 wt.%. The phase transformation behavior from amorphous to ThMn12 phase during heat treatment was systematically investigated by transmission electron microscopy. The remanent magnetization and maximum energy product of a bulk magnet were 96.0 emu/g and 12.22 MGOe, respectively. To the best of our knowledge, the achieved maximum energy product is the highest among all the SmFe12-based bulk magnets reported.

This study contains the process of developing a Mission Planning System (MPS) of an USV that can be applied in real situations and verifying them through HILS. In this study, we set the scenario of a single USV with limited operating time. Since the USV may not perform some missions due to the limited operating time, an objective function was defined to maximize the Mission Achievement Rate (MAR). We used a genetic algorithm to solve the problem model, and proposed a method using a 3-D population. The simulation showed that the probability of deriving the global optimal solution of the mission planning algorithm was 96.6% and the computation time was 1.6 s. Furthermore, USV showed it performs the mission according to the results of the MPS. We expect that the MPS developed in this study can be applied to the real environment where USV performs missions with limited time conditions.

Freestanding graphene on a trench has been fabricated extensively using a transfer process of chemical vapor deposition grown graphene. Here, we demonstrate that freestanding graphene can be grown directly on a trench without a transfer process. A shallow trench was made on a 6H–SiC(0001) wafer using a focused ion beam lithography. The shallow trench was heated to a high temperature under Ar atmosphere. The heat treatment made the shallow trench become deeper and wider. Subsequently, epitaxial graphene was floating on the trench, resulting in freestanding graphene, where underlying bulk SiC was self-etched after the growth of epitaxial graphene. The freestanding graphene on a trench was characterized using Raman spectroscopy and atomic force microscopy. Such freestanding graphene writing can be applied to semiconductor fabrication process of freestanding graphene devices without a transfer process.

Mathematical models with small numbers of parameters are useful for hydrological analyses and water resources planning as they are easier to prepare, use, and interpret compared to more complex models. Many simple model structures and simulation strategies have been developed, but there is still substantial room for improvement in the efficiency of daily rainfall-runoff modeling. This study proposes daily rainfall-runoff models that require only two to four parameters yet are capable of predicting peak discharge and baseflow. Parsimonious model structures were obtained using the hyperbolic tangent function and combining it with one subsurface layer and two parameters of a Tank model. The daily rainfall-runoff models proposed based on the Two-Parameter Hyperbolic Model (TPHM) and Tank model were applied to 41 watersheds throughout South Korea. Model accuracy was evaluated by comparing observed and simulated watershed streamflow and compared with that of a nine-parameter Tank model. The original TPHM and its variants yielded slightly better efficiency with a smaller number of parameters than the Tank model when reproducing high flows on a daily basis. The accuracy of low flow and flow duration curve predictions provided by the TPHM-based models was higher in watersheds with relatively large baseflow temporal variability. The results suggested that the TPHM-based structures be alternative parsimonious daily rainfall-runoff simulation models. This study demonstrates that daily high streamflow can be efficiently simulated using a two-parameter hydrological model, and daily baseflow simulation can be improved by adding two additional parameters to the model.

The isotropic nanoparticles (NPs) and anisotropic bulk samples of MnBi were prepared from Mn NPs by using zero-field and field-assisted reactive sintering, respectively. The MnBi NPs are irregular in shape with size d

Photodiodes composed of graphene and other two-dimensional materials are potential for high-sensitivity self-powered photodetectors, but the photovoltaic effect of graphene-based two-dimensional heterojunctions is often depressed and is, therefore, weaker than what it is expected. In this work, we have revealed that the loss of zero-bias photocurrent in the molybdenum disulfide (MoS2)/graphene photodiode originates from the interlayer coupling of photocarriers at the interface. By introducing atomically thin hexagonal boron nitride (h-BN) film into the MoS2/graphene interface, the interlayer carrier coupling at the MoS2/graphene interface under zero-bias is substantially blocked by the h-BN layer while the transport of photo-generated holes is realized through quantum tunneling. Therefore, the insertion of h-BN could increase the zero-bias photocurrent of the MoS2/graphene heterojunction for over three orders, and a high-sensitivity self-power vertical MoS2/h-BN/graphene van der Waals (vdW) heterostructure tunneling photodetector can be developed, which exhibits a high photo conversion efficiency (external quantum efficiency over 80%), improved photocurrent to dark current ratio (over 1000) and a corresponding high specific detectivity (5.9 × 1014 Jones for white-noise limited detectivity and 6.7 × 1010 Jones for the measured detectivity). This intriguing photovoltaic effect restoring has significant potential in practical applications of high-sensitivity graphene-based self-powered photodetection.

The low temperature phase Mn55Bi45-xGax (x = 0, 1, 3, 5, and 10) alloys were prepared by induction melting process with subsequent low temperature annealing. The effects of Ga-doping on the crystal structure and magnetic properties of the alloys were systematically studied. The room temperature coercivities of Mn55Bi45-xGax after ball milling increased from 1.43 T for x = 0 to 1.66 T for x = 5, while the saturation magnetization decreased from 60.7 Am2/kg (x = 0) to 45.1 Am2/kg (x = 5). The maximum energy product (BH)max of Mn55Bi44Ga powders reached 7.87 MGOe. The Curie temperature of the Mn55Bi45-xGax alloys increased from 633 K to 658 K with increasing Ga concentration in the range of 0 ≤ x ≤ 5.

The temperature for phase transformation of e → τ in Mn 54 Al 46 C x (hereafter denoted by MnAlC x , x = 0–5) alloys was systematically studied by using the traditional thermal analysis method and a more precise magnetic measurement method developed in this work. The effect of carbon content and cold-rolling on the magnetic properties of the MnAlC x alloys was studied. The onset temperature of massive growth of τ- from e-phase increases with increasing carbon content in MnAlC x . The carbon content has little effect on the onset temperature of displacive growth of e → τ but has substantial effect on the displacive growth rate at certain temperature. Pure τ-MnAlC x with varied x was obtained by annealing the e-phase at optimum temperatures determined by our method. The Curie temperature of the MnAlC x decreases significantly first and then increases slightly with increasing carbon content. The coercivity and the remanent magnetization of the as-prepared τ-MnAlC x increase with increasing x first and become stable at x > 3 and x > 4, respectively. A cold-rolling method was introduced in this work to enhance the magnetic properties of τ-MnAlC x . The coercivity and remanent magnetization of the τ-MnAl after cold-rolling were enhanced up to 4.3 times and 3.3 times, respectively. The coercivity of the cold-rolled τ-MnAlC x decreases with increasing x and becomes stable when x > 2. The remanent magnetization and saturation magnetization of the cold-rolled τ-MnAlC x vary little with x .

The Sn addition MnBi bulk magnets with high density and superior coercivity (Hc) were prepared by hot compaction. It was found that the added Sn was dispersed between the MnBi particles as an intergranular phase. The appropriate intergranular phase content could be beneficial in improving the Hc due to the strong magnetic isolation effects. The Hc of the MnBi/Sn bulk magnet was increased from 8.6 kOe to 11.5 kOe as the Sn addition contents were increased in the range of 0 wt.% to 5 wt.%. A relatively high squareness (Mr/Ms) of 0.91 was obtained for the 1 wt.% Sn addition Mn56Bi44 bulk magnet exhibiting the maximum energy product (BH)max of 7.8 MGOe with high Hc of 10 kOe at room temperature.

We have calculated electronic structures of Mn4C using first-principles calculations based on density functional theory (DFT) within the Perdew Burke Ernzerhof-generalized gradient approximation (PBE-GGA). The calculated band structures and density of states (DOS) indicate that stability of cubic perovskite-type crystal structured Mn4C is originated from p-d hybridization between Mnb and C and d-d hybridization between Mna and Mnb sublattices. The mean field approximation (MFA) resulted in the Neel temperature (TN) of 879 K which is in close agreement with experimental TN. The temperature dependence of magnetic moments of Mna and Mnb sublattices were also calculated using the Brillouin function to investigate the origin of unusual linearly increasing magnetization below 400 K. It was found that the increasing magnetization is originated from strong mutual interdependence of more or less linearly decreasing magnetic moment of Mna and stationary magnetic moment of Mnb below 400 K.

Two dimensional (2D) p-MoTe2 channel-based nonvolatile memory transistors with ferroelectric P(VDF-TrFE) polymer has been studied using a bottom-gate device architecture, which is introduced to dramatically reduce both of the switching and drain voltages to minimum 8 V and 10 mV, respectively. In fact, most of 2D-channel ferroelectric FETs with the same P(VDF-TrFE) polymer have used top-gate architectures, utilizing high switching pulse voltages over 20–25 V due to the existence of dead layer, which is unavoidably formed at the interface between P(VDF-TrFE) and thermal-deposited Al top gate. Key effects to realize such a low 8–13 V switching thus originate from the bottom-gate architecture. On the one hand, keys to obtain the low operation/drain voltage come from anneal-free Ohmic contact which is obtained using H2O2 solution. Thanks to the low operation voltages of 10 mV, consuming power in the nonvolatile FETs can be minimized to ~a few pW for OFF/Erase state and ~a few hundred pW for ON/Program although it eventually becomes ~nW and ~30 nW for OFF and ON states in a practical circuit operation to switch organic light emitting diodes. Our approaches of bottom-gate architecture and H2O2 contact nicely work even for transparent nonvolatile memory FET.

Sensitivity analysis plays an important role in geoscientific computer experiments, whether for forecasting, data assimilation or model calibration. In this paper we focus on an extension of a method of regionalized sensitivity analysis (RSA) to applications typical in the Earth Sciences. Such applications involve the building of large complex spatial models, the application of computationally extensive forward modeling codes and the integration of heterogeneous sources of model uncertainty. The aim of this paper is to be practical: 1) provide a Matlab code, 2) provide novel visualization methods to aid users in getting a better understanding in the sensitivity 3) provide a method based on kernel principal component analysis (KPCA) and self-organizing maps (SOM) to account for spatial uncertainty typical in Earth Science applications and 4) provide an illustration on a real field case where the above mentioned complexities present themselves. We present methods that extend the original RSA method in several ways. First we present the calculation of conditional effects, defined as the sensitivity of a parameter given a level of another parameters. Second, we show how this conditional effect can be used to choose nominal values or ranges to fix insensitive parameters aiming to minimally affect uncertainty in the response. Third, we develop a method based on KPCA and SOM to assign a rank to spatial models in order to calculate the sensitivity on spatial variability in the models. A large oil/gas reservoir case is used as illustration of these ideas.

Graphene and hexagonal boron nitride (hBN) heterostructures have attracted considerable attention in recent years to keep graphene's unique properties with ideal two-dimensional protective layers of h-BN for use in a wide range of potential applications. Depending on the application goals and the fabrication process, several structural configurations of graphene and hBN have been suggested; (1) lateral heterostructure incorporated in the in-plane direction on the same layer like graphene-hBN and (2) vertical heterostructures stacking a layer over different layers like graphene/hBN(GB), hBN/graphene(BG) or hBN/graphene/hBN(BGB). These artificial heterostructures can induce new properties or preserve the ideal unique properties beyond the inevitable limit of pristine graphene caused during the conventional fabrication. In this perspective, recent advances in selective synthesis or controllable fabrication of graphene and hBN heterostructures are summarized. In particular, with practical scalability, high uniformity and quality, in situ chemical vapor deposition growth of in-plane and vertical graphene and hBN heterostructures are highlighted.

Two-dimensional (2D) hexagonal boron nitride (h-BN) is a thin insulating material that can be used to enhance the electrical and optical properties of other 2D materials when used as a substrate or a capping layer, owing to its absence of dangling bonds on the surface. The use of multilayer h-BN films is often required in such applications to realize high material performance. However, previous works have focused mostly on the synthesis of monolayer or few-layer h-BN films. Herein we report a method to control the thickness of h-BN film up to the centimeter scale by means of plasma-enhanced chemical vapor deposition (PECVD). The thickness of the h-BN film is controlled by varying the deposition time of borazine precursor onto a monolayer h-BN film on a Pt foil substrate at room temperature. The resultant film is then annealed at high temperature (1050 °C) to increase the crystallinity of the h-BN. Monolayer h-BN film grown on Pt foil used as a buffer layer is of importance to improve uniformity and smooth surface of the multilayer h-BN film over the whole area. We further demonstrate that our multilayer h-BN film is very useful in graphene/h-BN/SiO2 heterostructures as a charge-blocking layer between graphene and SiO2.

We report a low magnetic loss Ba3Co2Fe24O41 (Co2Z) hexaferrite for use in gigahertz (GHz) antennas. Acid-etching was very effective in removal of unwanted Y-type hexaferrite (Ba2Co2Fe12O22) from calcined Co2Z powder. It is found that the calcined and acid etched (AE) Co2Z hexaferrite shows a low magnetic loss tangent (tan δμ) of 0.012 and 0.037 at 1 and 2 GHz, respectively. These low tan δμ are attributed to removal of Y-type hexaferrite, which possesses a lower anisotropy field (Hk) than W-type hexaferrite (BaCo2Fe16O27). The figure of merit (FOM) of the AE Co2Z hexaferrite is 141.7 and 48.7 at 1 and 2 GHz, respectively. These FOM are much higher than the FOM of previously reported low-loss magnetic materials. Therefore, the AE Co2Z hexaferrite can be a good candidate for GHz antenna application in the ultra-high frequency (UHF) band.

Structure and magnetic properties of Fe-doped MnBi alloy with a range of Fe concentrations were systematically investigated. The coercive field and saturation magnetization (Ms) were drastically changed according to the fabrication methods and Fe contents. The addition of Fe element could enhance the coercivity (Hc) of the MnBi-based alloy, and the increased Hc of 1.76 T was reached in the Mn55Bi45-Fe (15 wt%) ball-milled ribbon. Moreover, a high remanence ratio (Mr/Ms) of 97.0% was achieved in the Mn55Bi45-Fe (7.5 wt%) ball-milled ingot. In addition, as the concentration of Fe increases from 0 to 15 wt%, the Curie temperature (Tc) was increased from 635 to 652 K. This demonstrates that Fe-doped MnBi rare-earth permanent magnets could be a promising candidate for high-temperature applications. The relationship between magnetic properties and intermetallic lattice variations were discussed with precise Rietveld refinement analysis.

High purity MnBi magnetic low temperature phase (LTP) were prepared via induction melting, annealing and low energy ball milling. The effects of synthetic parameters and chemical compositions on phase purity and magnetic properties were systematically investigated. A homogenization heat treatment process was employed to increase the fraction of LTP MnBi, which showed notably high saturation magnetization (Ms) of up to 74.8 Am2/kg with the purity of 97 wt% LTP MnBi. The purity of MnBi is strongly related to the amount of Mn and residual Bi in the annealed ingot. By controlling the residue, the highest phase fraction was obtained with the atomic ratio of Mn56Bi44. The maximum energy product (BH)max was recorded 11.7 MGOe under an applied magnetic field of 1.5 T at room temperature, making MnBi a promising rare-earth-free permanent magnet.

Direct forecasting has recently been proposed as a method for uncertainty quantification in non-linear inverse problems. The method directly forecasts a desired future response without the need for full model inversion. The method has been successfully applied to a range of subsurface field cases, such as groundwater, shallow and deep geothermal and oil/gas predictions. In this paper, we extend the framework of direct forecasting to do what it was avoided to do in the first place: model inversion. The idea is simple: replace the prediction variables with the model variables. Two challenges now occur: the model dimensions, in subsurface realm at least, are much higher than data variables. This is the case in the paper where we consider dynamic data and high-dimensional spatial models for geological structure and properties. Secondly, the regression applied in the original method, being a linear regression of prediction variables on transformed data, is unlikely to lead to models that match field observations. We address these challenges first by adding a variable selection method (through global sensitivity analysis) for the model space. More specifically, we select those model components that are most sensitive to data variables only. The linear assumption is mitigated by a sequential updating of sensitive model variables. We illustrate our method on a Libyan oil reservoir with complex geological uncertainty involving structural, petrophysical and fluid model parameters.

Exchange coupled hard/soft MnBi/Fe–Co core/shell structured composites were synthesized using a magnetic self-assembly process. MnBi particles were prepared by arc-melting, and Fe–Co nanoparticles were synthesized by an oleic acid assisted chemical reduction method. Grinding a mixture of micron-sized MnBi and Fe–Co nanoparticles in hexane resulted in MnBi/Fe–Co core/shell structured composites. The MnBi/Fe–Co (95/5 wt%) composites showed smooth magnetic hysteresis loops, enhanced remanent magnetization, and positive values in the ΔM curve, indicating exchange coupling between MnBi and Fe–Co particles.

We report a facile method for fabricating a flexible plane heater on a plastic substrate using a graphite and carbon nanotube hybrid nanocomposite. To scale up to an industrial level, all the processes are applied in a conventional manner including three-roll calendar and screen printing. Bare graphite flakes are used as a main filler to increase the electrical conductivity of the nanocomposite. To preserve the high crystallinity of graphite, chemical treatments are excluded during the process. A small amount of amino-functionalized multi-walled carbon nanotubes (a-MWCNTs) (10 wt%) are added not only to increase the mechanical strength of the plane heater, but also to improve the heat conduction in the nanocomposite. Therefore, while graphite nanocomposite film mostly peeled off after an adhesion test, a-MWCNT-graphite nanocomposite film adhered on the PET substrate without noticeable change. Furthermore, the fabricated plane heater shows the high performance, compared to that of a graphite nanocomposite, a carbon black/graphite nanocomposite, and Cu wire heaters. We demonstrate that our plane heater is applicable for heating seats of commercial vehicles as well as a flexible plane heater. It will be applied to numerous areas such as heating systems in electrical vehicle and household items for heating.

Hollow spherical BaFe12O19 particles were synthesized by spray pyrolysis from a solution containing ethylene glycol (EG) and precursors at 1000 degrees C. The effects of EG concentration on particle morphology, crystallinity and magnetic properties were investigated. The hollow spherical particles were found to consist of primary particles, and higher EG concentration led to a bigger primary particle size. EG concentration did not show much effect on the hollow particle size. Better crystallinity and higher magnetic coercivity were obtained with higher EG concentration, which is attributed to further crystallization with the heat produced from EG combustion. Saturation magnetization (emu/g) decreased with increasing EG concentration due to residual carbon from EG incomplete combustion, contributing as a non-magnetic phase to the particles. Published by Elsevier B.V.

Epitaxial growth to synthesize core/shell-structured materials is limited because large lattice mismatches are common between materials. Magnetically hard/soft, core/shell-structured materials can be potentially used for rare-earth free permanent magnets, but their synthesis presents a challenge. We report a wet chemistry method to synthesize core/shell structured particles consisting of a magnetically hard SrFe12O19 core and a soft Fe–Co shell, with a lattice mismatch of ∼100%, which cannot be achieved by conventional epitaxial growth or other alternative methods. When decreasing the size of the magnetically soft Fe–Co nanoclusters to below 5 nm, we show that they can be magnetically attracted by the hard SrFe12O19 to form core/shell structured particles. An AC demagnetization experiment demonstrates the formation mechanism of the core/shell particles, and their magnetic hysteresis loop shows potential for use as rare-earth free permanent magnets.

A facile method is reported to synthesize hollow mesoporous BaFe{sub 12}O{sub 19} spheres using a template-free chemical etching process. Hollow BaFe{sub 12}O{sub 19} spheres were synthesized by conventional spray pyrolysis. The mesoporous structure is achieved by alkaline ethylene glycol etching at 185 °C, with the porosity controlled by the heating time. The hollow porous structure is confirmed by SEM, TEM, and FIB-FESEM characterization. The crystal structure and magnetic properties are not significantly affected after the chemical etching process. The formation mechanism of the porous structure is explained by grain boundary etching. - Graphical abstract: Hollow spherical BaFe{sub 12}O{sub 19} particles are polycrystalline with both grains and grain boundaries. Grain boundaries have less ordered structure and lower stability. When the particles are exposed to high temperature alkaline ethylene glycol, the grain boundaries are etched, leaving small grooves between grains. These grooves allow ethylene glycol to diffuse inside to further etch the grains. As the grain size decreases, gaps appear on the particle surfaces, and a porous structure is finally formed. - Highlights: • Two-step synthesis method for hollow mesoporous BaFe{sub 12}O{sub 19} spheres is proposed. • Porosity of the product can be regulated by controlling the second step of chemical etching.more » • The crystal structure and magnetic properties are examined to be little affected during the chemical etching. • The mesoporous structure formation mechanism is explained by grain boundary etching.« less

The site occupancy and magnetic properties of aluminum-substituted barium hexaferrite BaAlxFe12−xO19, with the fraction of Al between x = 0.5 and x = 4, has been investigated using density-functional theory within the spin-polarized generalized-gradient approximation. Our results show that Al3+ ions preferentially occupy the 2a and 12k sites, and exclude the occupancy of 4f1 and 4f2 sites (which were not ruled out in previous experimental studies due to the lack of conclusive data). Our results also show that the saturation magnetization decreases monotonically with the increase of Al concentration in agreement with the available experimental data.

Anisotropic transmission through a plasmonic bull's eye with an elliptical central aperture in a thin Au film is analyzed experimentally by changing the polarization. The light polarized along the minor axis of the elliptical aperture had a significantly larger enhanced optical transmission than the other orthogonal polarization, which agreed well with theoretical predictions. Spectral width of the output was narrowed, which indicates temporal elongation of pulse trains.

The electronic structure of hexagonal strontium ferrite (SrFe12O19) was calculated based on the density functional theory (DFT) and generalized gradient approximation (GGA). The GGA+U method was used to improve the description of localized Fe 3d electrons. Three different effective U (Ueff) values of 3.7, 7.0, and 10.3 eV were used to calculate three sets of exchange integrals for 21 excited states. We then calculated the temperature dependence of magnetic moments m(T) for the five sublattices (2a, 2b, 12k, 4f1, and 4f2) using the exchange integrals. The m(T) of the five sublattices are inter-related to the nearest neighbors, where the spins are mostly anti-ferromagnetically coupled. The five sublattice m(T) were used to obtain the saturation magnetization Ms(T) of SrFe12O19, which is in good agreement with the experimental values. The temperature dependence of maximum energy product ((BH)max(T)) was calculated using the calculated Ms(T).

Volatile organic compounds (VOCs) are potentially harmful air pollutants that are commonly encountered in urban environments. Various chemicals known to produce VOCs are used in laboratory fume hoods; however little research has been done to show the effect of such chemicals and associated VOCs on the local air quality. This study aims to assess the concentration of various VOCs emitted from the exhaust stacks of rooftop fume hoods mounted on laboratory buildings, as well as to determine factors that contribute to different concentrations of commonly encountered VOCs. A total of six university campus buildings, comprising four laboratory buildings and two non-laboratory buildings as controls, were selected as case studies. VOCs were sampled using activated charcoal tubes in front of fume hood exhausts located on the rooftops of buildings and were analyzed GC/FID. Factors such as meteorological conditions and the amount of chemicals utilized in the building of interest were investigated. A total of 11 individual compounds were quantified in the samples collected. The concentrations of 11 VOCs at laboratory buildings were significantly higher (GM; 184.74 μg/m3, GSD; 3.38) than those of non-laboratory buildings (GM; 12.1 μg/m3, GSD; 1.64, p

Perovskite photovoltaic (PV) cell researches have been extensively conducted due to its unprecedentedly excellent power conversion efficiencies (PCEs), which are reported to be over 23.7% in maximum. Despite the high PCEs, there are several unresolved issues on optimal interface states in the cell and device stabilities. Moreover, beyond the simple PV device issues, extended device or circuit applications have rarely been reported although it seems equally important to fully reveal the self-power energy harvesting functions of the perovskite cells to modern ubiquitous environment. Here, we integrate a realistic self-power circuit utilizing a few nm-thin molybdenum ditelluride (MoTe2) field effect transistors (FETs) as well as perovskite PV cells. The PV cells intrinsically show more than 0.9 V of open circuit voltage (VOC) under artificial sun (AM 1.5) or visible photon illumination, so we thus used a red-light emitting diode (LED) to simply generate ~1 V of photovoltage. Two modes for practical operation were consequently observed from the circuit, depending on the light intensity: self-power current/voltage source mode (high intensity) and photosensor mode (low intensity). We now conclude that our self-power circuit approaches integrating perovskite cells and 2D MoTe2 FET could attract much attention for future ubiquitous electronics and energy harvest applications.

We report on the anisotropic properties of solution-processed thin-film transistors (TFTs) fabricated by the vertical flowing of the viscous 6,13-bis(triisopropylsilylethynyl) pentacene (TIPS-pentacene) and isotactic (i-) poly-(methyl methacrylate) (PMMA) blend. During film formation processes, lateral crystalline growth of TIPS-pentacene and TIPS-pentacene/i-PMMA phase-separation were observed. Such anisotropic crystallization of TIPS-pentacene channel caused anisotropic mobility with respect to the channel orientation, so that it could be used for composing of a logic inverter where two TFTs with different channel orientations were serially connected.

Magnetic domain patterns in bulk barium ferrite (BaFe12O19; BaM) single crystals on the basal plane and the prism plane were measured and studied by magnetic force microscopy (MFM). The surface domain pattern is in the form of flowers or star on the basal plane and long elongated spikes or stripe domains on the prism plane. The change in domain structure with applied field (Happ) and the thickness (T) dependence on domain width (δ) was observed. The domain width decreased from 32 to 9 μm for the crystals of 800–100 μm thicknesses, respectively.

Electrical properties of three kinds of poly(methyl methacrylate) (PMMA) with different tacticity, i.e. isotactic(i), syndiotactic(s), and atatic(a), were investigated for the application in field effect transistor. Metal-insulator-silicon structures were fabricated via spin coating PMMA on heavily doped p-type silicon (p+-Si) followed by evaporating gold electrode. The electrical characteristics were remarkably improved by heat-treatment at temperatures 40 K above glass transition temperatures of PMMAs. Among the three PMMA isomers, i-PMMA was observed to possess the highest dielectric strength (1.1 MV/cm) with the lowest leakage current density, but also the lowest dielectric constant (k = 2.5). Top-contact thin film transistors fabricated with the configuration of NiOx/pentacene/i-PMMA/p+-Si, where the NiOx being used as a source/drain electrode, displayed relatively a decent field effect mobility of 0.042 cm2/V-s which is not that low with such a low dielectric capacitor as thick i-PMMA film.

Although a shade tab in a shade guide is matched to a natural tooth in the order of value, hue, and chroma, there are limited data on the color distribution of currently available shade guides sorted by these 3 parameters. Furthermore, spectrophotometric color measurements of shade tabs differ depending on the standard illuminant employed.The purpose of this study was to determine the color distributions of 2 shade guides in value (CIE L( *)), chroma (C( *)(ab)) and hue angle (h(o)) scale relative to the standard illuminants D(65), A, and F2.Color of shade tabs (n=36) from 2 shade guides (Vita Lumin and Chromascop) were measured, and the distributions for CIE L( *), C( *)(ab) and h(o) values were compared. Color differences of shade tabs depending on the illuminant were calculated. The distributions of the ratios of CIE L( *) and C( *)(ab) values of each shade tab compared with the lowest value tab or the lowest chroma tab were determined. The data for the value, chroma, and hue angle within each shade guide were analyzed with a 2-way ANOVA with the factors of shade designation and type of illuminant (alpha=.05). Color difference caused by change of illuminant was analyzed with a 2-way ANOVA with the factors of shade designation and pair of illuminants compared (alpha=.05). The Scheffe multiple comparison test was performed as a post hoc test.CIE L( *), C( *)(ab) and h(o) values were influenced by shade designation and type of illuminant in both shade guides. Color difference caused by change of the illuminant was influenced by the shade designation and pair of illuminants compared. The order of mean color differences of 16 Vita Lumin shade tabs by pairs of illuminants compared was as follows: DeltaE( *)(ab) (D(65)/F2) = 1.63DeltaE( *)(ab) (D(65)/A) = 2.22DeltaE( *)(ab) (A/F2) = 2.46 (P.05). The order of mean color differences of 20 Chromascop shade tabs was as follows: DeltaE( *)(ab) (D(65)/F2) = 2.45DeltaE( *)(ab) (D(65)/A) = 2.71DeltaE( *)(ab) (A/F2) = 3.14 (P.05). The distributions of value and chroma in both shade guides were arbitrary.Color distribution of 2 shade guides varied by the illuminant, and the range of color difference for shade tabs by the illuminant was 0.80 to 4.82, which may be clinically unacceptable (DeltaE( *)(ab)3.7). Color distribution of 2 shade guides by the value and chroma was not logical.

Poly(vinyl acetate) (PVAc) is currently being investigated as a potential polymeric gate insulator for organic thin film transistors (OTFTs), because it can be easily converted from poly(vinyl alcohol) through hydrolysis and can form a composite material with inorganic particles. In addition, the PVAc with a dielectric constant of 3.2–9.3 can be adopted as a good gate insulator for the OTFTs. We report characteristics of the electric transport of pentacene based OTFT using PVAc material with and without organic montmorillonite (OMMT) layer as a polymeric gate insulator. Spin coating condition of the gate insulator with PVAc was measured considering both viscositiy of PVAc dissolved in chloroform as a function of PVAc concentration and surface morphology after the spin coating process.

We report the physical characteristics of poly(vinyl acetate) (PVAc) as a polymeric gate insulator in the organic thin film transistors (OTFTs), in which the OTFTs require not only a simple packing process with a relatively low cost compared to conventional inorganic electronics but also their compatibility with flexible substrates. The PVAc gives dielectric constant values in the range of 3.2–8.3, which can be adopted as a good gate insulator for OTFTs. The fabricating condition of OTFTs using the PVAc was improved by both adjusting its viscosity with that of a medium, and controlling the surface morphology and spin coating conditions. All these meet the requirement for a new organic gate-insulator, which can improve the performance of the present OTFTs.

The motion of nanoscale structures made of pure crystalline silicon with different lattice conditions is simulated in vacuum by applying the molecular dynamics technique with the use of the Tersoff potential. Elastic moduli for various sized specimens are obtained by simulating flexural and longitudinal vibrations as well as simple tension tests. Compared with the bulk silicon, the elastic modulus decreases monotonically by as much as 40% as the thickness of the specimen decreases, and the presence of voids in the specimen further decreases the modulus by a significant amount. Estimation of thermal fluctuations and feasibility study of nanoscale cantilevers as molecular mass sensors demonstrate that the continuum-theory-based analysis can still be used on nanoscale structures provided the dependence of the elastic constants on dimensional scaling is accounted for.

Pulse electric field induced electron emission from the Pb(Zr0.65Ti0.35)O3 ferroelectric films has been investigated as a function of the film thickness from 0.2 to 4.0 μm and the upper electrode diameter from 200 to 1100 μm. The electron emission charge from the 3.0 μm film was several nC per pulse, which was comparable to that of the bulk ferroelectrics. However, the local dielectric breakdown occurred in the films below 1.0 μm without the electron emission, which was confirmed by the optical microscopy observation after the emission tests. As the upper electrode size decreased and the film thickness increased, electrons were more easily emitted without breakdown.

We demonstrate the fabrication of semi-transparent pentacene-based thin-film transistors (TFTs) with thin poly-4-vinylphenol (PVP)/high- k yttrium oxide (YO x ) double gate dielectric layers and also with thermally-evaporated NiO x source/drain (S/D) electrodes which show a transmittance of ∼ 30–40% and sheet resistance range of 100–200 Ω/□ (controlled by deposition rate). Our pentacene TFTs with PVP (45 nm)/YO x (100 nm) layers operated at less than − 5 V, exhibiting a decent saturation mobility (maximum 0.83 cm 2 /Vs) and on/off current ratios of 10 4 . When the sheet resistance of our semi-transparent NiO x electrode increased from 100 Ω/□ to 200 Ω/□, the field mobility of our TFT decreased but was found to be still effective as 0.32 cm 2 /Vs.

YBa2Cu3O7−δ (YBCO) films were grown on Si using a buffer layer of yttria-stabilized zirconia (YSZ) by pulsed laser deposition. Interconnections between the YBCO film and the Si substrate using Au have been fabricated by lithography. The YBCO films showed zero-resistance critical temperatures in the range of 80–85 K and were found to be grown in the c–axis orientation. The structural properties of the films of various thicknesses were analyzed by XRD, SEM and Raman spectroscopy. Because of very different thermal expansion coefficients of Si and YBCO, there is a tendency to crack formation for films. The crack formation interrupts the current flow and increases the normal state resistance of the films. The effect of cracks on the contact resistances between YBCO films of various thicknesses and Si substrates through Au interconnections is reported.

Pb(Zr x Ti 1− x )O 3 (0.3≤ x ≤0.6) thin films modified by 10 mol% Pb(Mg 1/3 Nb 2/3 )O 3 (PMN) have been prepared by chemical solution deposition with corresponding metal alkoxides. The films were nearly pure perovskite phase with preferentially (1 1 1)-orientation. The microstructure was dense and uniform while grain size became smaller from ∼250 to ∼100 nm with increasing Zr concentration ( x ). Dielectric constant and remnant polarization ( P r ) showed maximum values at the composition of x =0.5 and were ∼1500 and ∼18 μC cm −2 , respectively. Also, it was found that the degrading tendency of remnant polarization of lead zirconate–titanate (PZT) film with test cycling was apparently suppressed due to the presence of PMN.

148 RESULTS OF LAPAROSCOPIC DAVYDOV TECHNIQUE IN 47 PATIENTS WITH CONGENITAL ABSENCE OF THE VAGINA: LAPAROSCOPIC PERITONEAL VAGINOPLASTY Ki-Hyun Park, MD, Joo-Hyun Park, MD, Hyo-In Yang, MD, Bo Ram Choi, MD, Jeong Hye Baek, MD, Yeon Hong, MD, SiHyun Cho, MD, Seok Kyo Seo, MD, Young Sik Choi, MD, Byung Seok Lee, MD Department of Obstetrics and Gynecology, Yonsei University College of Medicine, Seoul; SAM Ahnayang Hospital, Ahnayang, Korea