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The potential of biochar as sorptive media for removal of hazardous benzene in air
No full textAirborne benzene is hazardous even at sub-ppm levels. Therefore, an effective strategy is required for its removal, such as the use of a sorbent with large adsorption capacity or high breakthrough volume. To meet the goal, the performance for the removal of benzene was assessed by loading benzene at 5 Pa inlet partial pressure against seven types of biowaste-derived biochar: (1) paper mill sludge, (2) conventional biochar with magnetic properties, (3) biochar composites with carbon nanotubes (CNTs), (4) gasification biochar from mixed feedstock, (5) gasification biochar from a single feedstock, (6) modified gasification biochar, and (7) activated carbon (AC) as a reference. The 298 K maximum adsorption capacities (mg g(-1)), when measured at a benzene inlet pressure of 5 Pa (or 50 ppm in ultrapure nitrogen) and flow rate of 50 mL atm min(-1), varied widely for different biochars, from 0.35 (MS: Swine manure + plastic mulch film waste) to 144 mg g(-1) (XC-1: biochar from mixed feedstock); their 10% breakthrough volumes (BTV) were in the range of 0.22-492 L g(-1), respectively. The experimental data (capacity vs. benzene outlet partial pressure) could be fitted to either two or three linearized Langmuir isotherms with distinctive sorption mechanisms ((1) a retrograde region (Type III isotherm: 0 to similar to 0.2 Pa), (2) an intermediate pressure region (0.2 and 2.0 Pa), and (3) a higher pressure region (> 2 Pa)) which was also confirmed similarly by Freundlich, Dubinin-Radushkevich, and Elovich fitting. About 65% of the maximum capacity was achieved in the retrograde region. The strongest biochar sorbent, XC-1, showed similar performance as activated carbon to prove its feasibility toward air quality management (AQM) applications.This study was supported by a grant from the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT, & Future Planning (Grant No: 2016R1E1A1A01940995). This research acknowledges the support made by the R&D Center for Green Patrol Technologies through the R&D for Global Top Environmental Technologies funded by the Ministry of Environment (MOE). This work was also carried out with the support of the "Cooperative Research Program for Agriculture Science and Technology Development (Grant No: PJ012521032017)" from the Rural Development Administration, Republic of Korea. We also thankful to Dr. Kyoung S. Ro (USDA Agricultural Research Service, Washington DC, USA) for their kind support in preparing the biochar production
What makes you select a higher price option? Price-quality heuristics, cultures, and travel group compositions
No full textScenarios were designed to investigate the influence of price–quality heuristics among participants from the United States, Korea, and China for different tourism and hospitality services, in different consuming situations and in different social group contexts. The results revealed that as the scenarios moved from consuming alone and with an acquaintance to with a close family member, participants in each culture had a greater propensity to select the higher price option. These tendencies were the most evident among the Korean sample, whereas the Chinese sample did not differentiate between an acquaintance and a family member, and the U.S. sample indicated mixed results
Factors associated with non-initiation of latent tuberculosis treatment among healthcare workers with a positive interferon-gamma releasing assay
No full textDespite widespread use of the interferon-gamma release assay for the diagnosis of latent tuberculosis infection (LTBI), the initiation rate of and factors associated with LTBI treatment among healthcare workers (HCWs) have not been studied in depth. The aim of this study was to evaluate the initiation rate of LTBI treatment and also to identify any factors associated with non-initiation of LTBI treatment among HCWs. A retrospective cohort study of 293 HCWs with LTBI was performed at a teaching hospital in Korea. LTBI was diagnosed using QuantiFERON-TB Gold In-Tube tests (Cellestis Ltd., Carnegie, VIC, Australia). Of the 293 HCWs with LTBI, 189 HCWs (64.5%) visited an outpatient clinic for a medical consultation regarding LTBI treatment. Of these, 128 (67.7%) consented to LTBI treatment for a 43.7% LTBI treatment initiation rate. Upon multivariable analysis, having a liver disease or currently taking hepatotoxic drugs (adjusted odds ratio [OR] = 12.03, 95% confidence interval [CI] = 3.12-46.35), being a physician (adjusted OR = 14.01, 95%Cl = 2.82-69.74) and other patient-related HCWs (adjusted OR = 3.58, 95%Cl = 1.46-8.78), and years of employment ˃= 20 years (adjusted OR = 4.77, 95% CI = 1.74-13.12) were independent factors associated with the non-initiation of LTBI treatment. Upon bivariate multivariable analysis, while having a liver disease or currently taking hepatotoxic drugs (adjusted OR = 12.85, 95% CI = 3.06-55.92), being a physician (adjusted OR = 28.43, 95% CI = 4.78-169.28) and other patient-related HCWs (adjusted OR = 4.80, 95%Cl = 1.56-14.74), and years of employment ˃= 20 years (adjusted OR = 4.55, 95%Cl = 1.37-15.15) were factors associated with no outpatient clinic visit for a consultation of LTBI treatment, having a liver disease or currently taking hepatotoxic drugs (adjusted OR = 11.76, 95% CI = 2.68-51.73) and years of employment ˃= 20 years (adjusted OR = 5.29, 95%Cl = 1.38-20.19) were factors associated with refusal of LTBI treatment after a consultation. The overall initiation rate of LTBI treatment was suboptimal in HCWs with LTBI diagnosed using an interferon-gamma releasing assay. Having a liver disease or currently taking hepatotoxic drugs, being a physician and other patient-related HCWs, and years of employment ˃= 20 years were associated with non-initiation of LTBI treatment.This research was supported by a grant of the Korea Health Technology R&D Project through the Korea Health Industry Development Institute (KHIDI), funded by the Ministry of Health & Welfare, Republic of Korea (grant number: HI15C1234)
Adaptive Cooperation of Prefetching and Warp Scheduling on GPUs
No full textThis paper proposes a new architecture, called Adaptive PREfetching and Scheduling (APRES), which improves cache efficiency of GPUs. APRES relies on the observation that GPU loads tend to have either high locality or strided access patterns across warps. APRES schedules warps so that as many cache hits are generated as possible before the generation of any cache miss. Without directly predicting future cache hits/misses for each warp, APRES creates a warp group that will execute the same static load shortly and prioritizes the grouped warps. If the first executed warp in the group hits the cache, grouped warps are likely to access the same cache lines. Unless, APRES considers the load as a strided type and generates prefetch requests for the grouped warps. In addition, APRES includes a new dynamic L1 prefetch and data cache partitioning to reduce contentions between demand-fetched and prefetched lines. In our evaluation, APRES achieves 27.8 percent performance improvement.This paper is an extension of our previous study, "APRES: Improving Cache Efficiency by Exploiting Load Characteristics on GPUs," which appeared in the 43rd International Symposium on Computer Architecture (ISCA 2016). This work was partially supported by the National Research Foundation of Korea (NRF) grant funded by the Korea government (MSIP)(No. NRF-2018R1A2A2A05018941), the Technology Innovation Program (No. 10080590, Technology Development of Unified Memory System for Heterogeneous System Architecture) funded by the Ministry of Trade, Industry & Energy (MOTIE, Korea) and Korea Semiconductor Research Consortium (KSRC) support program for the development of the future semiconductor device, and the Graduate School of YONSEI University Research Scholarship Grants in 2017
A New P2-Type Layered Oxide Cathode with Extremely High Energy Density for Sodium-Ion Batteries
No full textHerein, a new P2-type layered oxide is proposed as an outstanding intercalation cathode material for high energy density sodium-ion batteries (SIBs). On the basis of the stoichiometry of sodium and transition metals, the P2-type Na-0.55[Ni0.1Fe0.1Mn0.8]O-2 cathode is synthesized without impurities phase by partially substituting Ni and Fe into the Mn sites. The partial substitution results in a smoothing of the electrochemical charge/discharge profiles and thus greatly improves the battery performance. The P2-type Na-0.55[Ni0.1Fe0.1Mn0.8]O-2 cathode delivers an extremely high discharge capacity of 221.5 mAh g(-1) with a high average potential of approximate to 2.9 V (vs Na/Na+) for SIBs. In addition, the fast Na-ion transport in the P2-type Na-0.55[Ni0.1Fe0.1Mn0.8]O-2 cathode structure enables good power capability with an extremely high current density of 2400 mA g(-1) (full charge/discharge in 12 min) and long-term cycling stability with approximate to 80% capacity retention after 500 cycles at 600 mA g(-1). A combination of electrochemical profiles, in operando synchrotron X-ray diffraction analysis, and first-principles calculations are used to understand the overall Na storage mechanism of P2-type Na-0.55[Ni0.1Fe0.1Mn0.8]O-2.J.-Y.H. and J.K. contributed equally to this work. This work was supported by the Global Frontier R&D Program (No. 2013M3A6B1078875) of the Center for Hybrid Interface Materials (HIM), funded by the Ministry of Science, ICT, and Future Planning; further support was provided by the Human Resources Development program (No. 20184010201720) of the Korea Institute of Energy Technology Evaluation and Planning (KETEP), funded by the Ministry of Trade, Industry, and Energy of the Korean government
Quantified Activity Measurement for Medical Use in Movement Disorders through IR-UWB Radar Sensor
No full textMovement disorders, such as Parkinson's disease, dystonia, tic disorder, and attention-deficit/hyperactivity disorder (ADHD) are clinical syndromes with either an excess of movement or a paucity of voluntary and involuntary movements. As the assessment of most movement disorders depends on subjective rating scales and clinical observations, the objective quantification of activity remains a challenging area. The purpose of our study was to verify whether an impulse radio ultra-wideband (IR-UWB) radar sensor technique is useful for an objective measurement of activity. Thus, we proposed an activity measurement algorithm and quantitative activity indicators for clinical assistance, based on IR-UWB radar sensors. The received signals of the sensor are sufficiently sensitive to measure heart rate, and multiple sensors can be used together to track the positions of people. To measure activity using these two features, we divided movement into two categories. For verification, we divided these into several scenarios, depending on the amount of activity, and compared with an actigraphy sensor to confirm the clinical feasibility of the proposed indicators. The experimental environment is similar to the environment of the comprehensive attention test (CAT), but with the inclusion of the IR-UWB radar. The experiment was carried out, according to a predefined scenario. Experiments demonstrate that the proposed indicators can measure movement quantitatively, and can be used as a quantified index to clinically record and compare patient activity. Therefore, this study suggests the possibility of clinical application of radar sensors for standardized diagnosis.This research was supported by Bio & Medical Technology Development Program (Next Generation Biotechnology) through the National Research Foundation of Korea (NRF) funded by the Ministry of Science, ICT, & Future Planning (2017M3A9E2064735
SELF-ASSEMBLED NANOCHAMBER ARRAYS FOR in-situ TEM OBSERVATION OF LIQUID-PHASE SAMPLES
No full textThis work presents a highly-ordered array of nanoscale chambers, capable of encapsulating liquid samples for TEM (transmission electron microscopy) imaging. The present nanochambers are formed with two layers of free-standing graphene and self-assembled nanopores in an AAO (anodic aluminum oxide) membrane, which improve a transparency for electron beam and uniformities in chamber sizes/distributions, respectively. We envision that the present work will enable us to efficiently observe nanoscale processes in liquid with high-resolution TEM.This work was supported by the Basic Science Research Program and the Convergence Technology Development Program for Bionic Arm through the National Research Foundation of Korea (NRF) funded by the Ministry of Education (2018R1D1A1B07050575) and the Ministry of Science and ICT (2015M3C1B2052811)
Effective Fabrication and Electrochemical Oxygen Evolution Reaction Activity of Gold Multipod Nanoparticle Core–Cobalt Sulfide Shell Nanohybrids
No full textInorganic hybrid materials with anisotropic noble-metal nanoparticle cores and cagelike transition-metal chalcogenide shells are promising candidates for a wide variety of applications. Herein, we report an effective fabrication method for gold multipod nanoparticle (GMN) core–cobalt sulfide shell (GMN@CoxSy) nanostructures. The unique cagelike morphology is successfully acquired within nanohybrids (GMN@CoxSy nanocages). The cobalt-based metal–organic frameworks can act as versatile sacrificial templates to the desired hybrid nanomaterials through solution-based etching approaches without any undesirable reshaping of GMNs, which are embedded within. Examination of the electrocatalytic oxygen evolution reaction (OER) of the prepared nanohybrids reveals that a type of GMN@CoxSy nanohybrid shows a substantially lower overpotential (η) value (345 mV) compared with those of GMNs (617 mV) and CoxSy nanomaterials (418 mV) at a current density of 10 mA cm–2. The enhanced OER performance is mainly attributed to the highly effective core–shell interfaces stemming from the unique multibranch topologies of the GMN cores as well as the optimized cobalt sulfide shells of the nanohybrids.This research was supported by National Research Foundation of Korea (NRF) grants funded by the Korean government (MSIP; Grants NRF-2015R1A4A1041631 and NRF-2016R1A2B4009281). This work was supported by the Hallym University Postdoctoral Fellowship Program of 2017 (HLM-PF-2017-0003 to H.D.M.)
Enhanced dissolution of valsartan-vanillin binary co-amorphous system loaded in mesoporous silica particles
No full textThe study was aimed to prepare a co-amorphous system of valsartan (VAL) with vanillin (VAN) for improving its solubility and dissolution followed by its confinement in mesoporous silica particles (MSPs) to stabilise the co-amorphous system and prevent its recrystallization. Amorphous VAL and VAN were obtained through quench-cooling and VAL/VAN binary co-amorphous system (VAL/VAN-CAS) was prepared through solvent evaporation technique. The particle size and morphology of VAL/VAN-CAS-MSPs were studied using scanning electron microscopy (SEM) and solid-state characterisation was performed by differential scanning calorimetry (DSC) and X-ray powder diffraction (XRPD). The in vitro dissolution was investigated by dialysis bag diffusion method. SEM analysis revealed irregular shaped VAL/VAN-CAS-MSPs with a size range of 5-25 mu m, while outcomes of DSC and XRPD confirmed the formation of VAL/VAN-CAS. The in vitro dissolution profiles demonstrated a significantly increased dissolution in first 60 minutes from VAL/VAN-CAS (similar to 68%) and VAL/VAN-CAS-MSPs (similar to 76%) compared to powder VAL (similar to 25%).This work was partially supported by Riphah Academy of Research and Education through the seed money grant programme of Riphah International University
Moment of Inertia and Friction Torque Coefficient Identification in a Servo Drive System
No full textThis paper proposes a new method to identify the mechanical parameters of a servo drive system, such as the moment of inertia and friction torque coefficients. Identification of the moment of inertia is essential for the design of a high-performance speed and position controller. Furthermore, the mechanical friction torque coefficients, such as the viscous and Coulomb friction torque coefficients, can be used to reduce the speed and position error without resorting to the use of a high gain for the speed controller. To simultaneously identify the moment of inertia and the friction torque coefficients, the proposed method uses the fact that the sinusoidal speed is in phase with the friction torque and out of phase with the torque for the moment of inertia. The proposed method is based on the speed control loop and the moment of inertia, and friction torque coefficients can be exactly obtained from a half-period integration of the torque reference of the low frequency sinusoidal speed control. Using computer simulations and experiments employing 600-W servo drive systems, the feasibility of the proposed method was verified.This work was supported by the New & Renewable Energy Core Technology Program of the Korea Institute of Energy Technology Evaluation and Planning (KETEP) granted financial resource from the Ministry of Trade, Industry & Energy, Republic of Korea under Grant 20163030031830