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Bi2O2Se has an intrinsically low thermal conductivity and a high Seebeck coefficient, which suggests as potential thermoelectric materials. However, pristine Bi2O2Se polycrystalline exhibits very low electrical conductivity. In this study, we investigated the influence of I doping in enhancing electrical conductivity of Bi2O2Se by synthesizing a series of Bi2O2Se1-xIx polycrystalline samples (x = 0, 0.0025, 0.005, and 0.0075). By I doping, the electrical conductivity was enhanced by significant increase in carrier concentration. The carrier concentration was increased more than 10 times 2.1–4.6 × 1019 cm-3 from 2.1 × 1018 of the undoped sample. As results, the maximum power factor was enhanced to 0.24 mW/mK2 for x = 0.0025 from 0.086 mW/mK2 of undoped Bi2O2Se at 300 K. The maximum power factor of 0.42 mW/mK2 was achieved for x = 0.05 sample at 790 K. These increases are discussed in terms of the increase in effective mass and weighted mobility. Additionally, the moderate reduction of thermal conductivity was observed in the I doped samples due to the point defect scattering. As a result, a maximum zT value was enhanced to 0.32, 0.35, and 0.33 for x = 0.0025, 0.005, and 0.0075) at 790 K, representing an improvement of more than 50% compared to 0.21 of the undoped Bi2O2Se (x = 0).

Recent electric vehicle multilayer ceramic capacitors (MLCCs) adopt submicron-sized solid-state synthesized BaTiO3 for dielectric layers for high reliability. Unlike BaTiO3 nanoparticles synthesized by the hydrothermal method, particle size distribution control becomes demanding with the solid-state synthesis. Here, BaTiO3 with 260 and 390 nm average particle sizes were synthesized using a solid-state method, and the dielectric properties of the samples sintered at 1100, 1150, and 1200°C were studied in terms of particle size distributions. Notably, BaTiO3 samples sintered with 260 nm particles with smaller grain sizes and lower tetragonality exhibited higher dielectric properties than those prepared with 390 nm particles. The reasons behind the high dielectric performance were found in the lower skewness of the 260 nm particles, which produced a higher density of the sintered sample. For electric vehicle MLCC BaTiO3, engineering their skewness is as important as controlling their grain size or tetragonality for high dielectric performance.

Background Owing to antiretroviral therapy (ART), acquired immune deficiency syndrome (AIDS)-related mortality has significantly decreased. Retaining in care is an essential step for human immunodeficiency virus (HIV) care cascade. This study investigated the incidence of and risk factors for loss to follow-up (LTFU) in Korean people living with HIV (PLWH). Materials and Methods Data from the Korea HIV/AIDS cohort study (including prospective interval cohort and retrospective clinical cohort) were analyzed. LTFU was defined as not visiting the clinic for more than 1 year. Risk factors for LTFU were identified using the Cox regression hazard model. Results The study enrolled 3,172 adult HIV patients (median age, 36 years; male 92.97%). The median CD4 T cell count at enrollment was 234 cells/mm³ (interquartile range [IQR]: 85 - 373) and the median viral load at enrollment was 56,100 copies/mL (IQR: 15,000 - 203,992). The total follow-up duration was 16,487 person-years, and the overall incidence rate of LTFU was 85/1,000 person-years. In the multivariable Cox regression model, subjects on ART were less likely to have LTFU than subjects not on ART (hazard ratio [HR] = 0.253, 95% confidence interval [CI]: 0.220 - 0.291, P <0.0001). Among PLWH on ART, female sex (HR = 0.752, 95% CI: 0.582 - 0.971, P = 0.0291) and older age (>50: HR = 0.732, 95% CI: 0.602 - 0.890; 41 - 50: HR = 0.634, 95% CI: 0.530 - 0.750; 31 - 40: HR = 0.724, 95% CI: 0.618 - 0.847; ≤30: reference, P <0.0001) were associated with high rate of retention in care. The viral load at ART initiation ≥1,000,001 (HR = 1.545, 95% CI: 1.126 - 2.121, ≤10,000: reference) was associated with a higher rate of LTFU. Conclusion Young and male PLWH may have a higher rate of LTFU, and an increased rate of LTFU may induce virologic failure. [ABSTRACT FROM AUTHOR]

OBJECTIVES: To assess the risk of lymphadenopathy following severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) vaccination. METHODS: A self-controlled case series design was used to determine whether the risk of lymphadenopathy was higher in the 1-day to 42-day risk interval after coronavirus disease 2019 (COVID-19) vaccination compared to the control period. In addition, subgroup analyses were conducted according to baseline characteristics, time since vaccination, and sensitivity analyses adjusted for the length of the risk interval. RESULTS: The risk of developing lymphadenopathy in the risk interval (1-42 days) after COVID-19 vaccination compared to the control period was significantly increased, with a relative incidence (RI) of 1.17 (95% confidence interval [CI], 1.17 to 1.18) when the first, second, and third doses were combined. The RI was greater on the day of vaccination (1.47; 95% CI, 1.44 to 1.50). In subgroup analyses by baseline characteristics, a significantly increased risk or trend toward increased risk was observed in most subgroups except for those aged 70 years and older, with a significant increase in risk in younger individuals, those with a Charlson's comorbidity index <5, and those who received mRNA vaccines (mRNA-1273>BNT162b2). Within the 1-day to 42-day post-dose risk period, the relative risk was highest during the 1-day to 7-day post-dose period (1.59; 95% CI, 1.57 to 1.60) compared to the control period, and then the risk declined. In the sensitivity analysis, we found that the longer the risk window, the smaller the RI. CONCLUSIONS: SARS-CoV-2 vaccination is associated with a statistically significant increase in the risk of lymphadenopathy, and this risk was observed only with mRNA vaccines. [ABSTRACT FROM AUTHOR]

Proximal junctional problems are among the potential complications of surgery for adult spinal deformity (ASD) and are associated with higher morbidity and increased rates of revision surgery. The diverse manifestations of proximal junctional problems range from proximal junctional kyphosis (PJK) to proximal junctional failure (PJF). Although there is no universally accepted definition for PJK, the most common is a proximal junctional angle greater than 10° that is at least 10° greater than the preoperative measurement. PJF represents a progression from PJK and is characterized by pain, gait disturbances, and neurological deficits. The risk factors for PJK can be classified according to patient-related, radiological, and surgical factors. Based on an understanding of the modifiable factors that contribute to reducing the risk of PJK, prevention strategies are critical for patients with ASD.

Abstract Zintl compounds are promising thermoelectric materials for power generation as their electronic and thermal transport properties can be simultaneously engineered with anion/cation alloying. Recently, a peak thermoelectric figure‐of‐merit, zT, of 1.4 was achieved in a (Yb0.9Mg0.1)Cd1.2Mg0.4Zn0.4Sb2 Zintl phase at 700 K. Although the effects of alloying Zn in lattice thermal conductivity had been studied thoroughly, how the Zn alloying affects its electronic transport properties has not yet been fully investigated. This study evaluates how the Zn alloying at Cd sites alters the band parameters of (Yb0.9Mg0.1)Cd1.6−xMg0.4ZnxSb2 (x=0‐0.6) using the Single Parabolic Band model at 700 K. The Zn alloying increased the density‐of‐states effective mass (md*) from 0.87 to 0.97 m0. Among Zn‐alloyed samples, the md* of the x=0.4 sample was the lowest (0.93 m0). The Zn alloying decreased the non‐degenerate mobility (μ0) from 71 to 57 cm2 s−1 V−1. Regardless of Zn alloying content, the μ0 of the Zn‐alloyed samples were similar (∼57 cm2 s−1 V−1). Consequently, the x=0.4 with the highest zT exhibited the lowest weighted mobility (μW). The lowest μW represents the lowest theoretical electronic transport properties among other x. The highest zT at x=0.4 despite the lowest μW was explained with a significant lattice thermal conductivity reduction achieved with Zn alloying with x=0.4, which outweighed the deteriorated electronic transport properties also due to the alloying.

Herein, we report a simple and scalable synthesis route to prepare Ag-functionalized porous ZnO sheets and their enhanced NO2 gas sensing properties. Porous ZnO sheets functionalized with well-dispersed submicron Ag particles were prepared by using a hydrothermal method-based one-pot synthesis route from Zn and Ag precursors. NO2 gas sensing performance (response, selectivity, response time, and recovery time) was optimized at 200°C in the gas sensor fabricated with 3 at% Ag-functionalized porous ZnO sheets. We demonstrated a response (Rg/Ra) of 17.18 to 10 ppm NO2 gas and also obtained a high response of 14.05 even at 60% relative humidity due to the synergetic effect of improved NO2 gas adsorption in the presence of Ag particles and increased resistance by the formation of Schottky barrier at Ag-ZnO heterojunctions.

Herein, we investigated the influence of sulfur (S) addition on the phase formation behavior and thermoelectric transport properties of n-type Cu0.008Bi2Te3. A complete single phase of rhombohedral Bi2Te3 was formed in Cu0.008Bi2Te2.8S0.2, whereas a mixture of Bi2Te3 and Bi2Te2S1 phases was generated at higher S contents. We elucidated the complex effects of S substitution at Te-site on transport properties of Cu0.008Bi2Te3; (1) increase in density-of-states effective mass, (2) decrease in weighted mobility ratio, (3) reduction in lattice thermal conductivity, and (4) reduction in bipolar thermal conductivity. Despite the slight deterioration in electronic transport properties, a maximum thermoelectric figure of merit (zT) of 0.82 was achieved at 400 K in Cu0.008Bi2Te2.8S0.2 due to the synergetic effect of intensified point defect phonon scattering in a wide temperature range and suppressed bipolar thermal conduction at elevated temperatures.

Abstract During lateral lumbar interbody fusion (LLIF), unintended intraoperative endplate injury (IEPI) can occur and thereafter lead cage subsidence. The aim of this study was to investigate the incidence of IEPI during LLIF, and its predisposing factors. A retrospective review was conducted on consecutive patients (n = 186; mean age, 70.0 ± 7.6 years) who underwent LLIF at 372 levels. Patient’s demographic and surgical data were compared between patients with and without IEPI. Also, the radiographic data of each level were compared between intact and IEPI segments. IEPI was identified at 76 levels (20.4%) in 65 patients. The incidences of IEPI at every 100 consecutive segments were not different. When 372 segments were analyzed independently, sagittal disc angle (DA) in the extended position (4.3° ± 3.6° at IEPI segments vs. 6.4° ± 4.0° at intact segments), the difference between sagittal DA in the extended position and cage angle (− 2.2° ± 4.0° vs. 0.0° ± 3.9°), and the difference between preoperative disc height and cage height (− 5.4 mm ± 2.4 mm vs. − 4.7 mm ± 2.0 mm) were different significantly. Also, endplate sclerosis was more common at intact segments than IEPI segments (33.2% vs. 17.3%). Multivariate analysis showed that male sex (odds ratio [OR] 0.160; 95% confidence interval [CI] 0.036–0.704), endplate sclerosis (OR 3.307; 95% CI 1.450–8.480), and sagittal DA in the extended position (OR 0.674; 95% CI 0.541–0.840) were significant associated factors for IEPI. IEPI was correlated not with surgeon’s experience, but with patient factors, such as sex, preoperative disc angle, and endplate sclerosis. Careful surgical procedures should be employed for patients with these predisposing factors.

(1) Background: Recently, Escherichia coli-derived recombinant human bone morphogenetic protein-2 (E. coli-derived rhBMP-2) has been increasingly applied to different types of spinal surgeries and reported to achieve successful fusion. This pilot study aimed to evaluate the clinical efficacy and safety of rhBMP-2 in patients undergoing posterior instrumented fusions for unstable spinal fractures. (2) Methods: This study included ten consecutive patients undergoing spinal surgery using E. coli-derived rhBMP-2 with more than one year of follow-up. Radiologic outcomes were compared, including the average fracture healing period, local kyphosis correction, and clinical outcomes between preoperative and the last follow-up. (3) Results: The average time of radiographic union was 99.9 ± 45.4 (62–192) days, with an average use of 5.2 ± 3.9 months of anabolic agents. Radiologic parameters such as anterior vertebral height and vertebral wedge angle were significantly corrected postoperatively and at the last follow-up. Clinical outcomes other than leg pain were significantly improved after the surgery. In addition, four patients with preoperative neurologic deficits showed improved neurologic status. (4) Conclusions: Combined with the anabolic agents, applying E. coli-derived rhBMP-2 to the fractured vertebral body could be an effective surgical treatment for unstable spinal fractures. Further trials are needed to validate this result.

Bi2Te3 is a good candidate to be used in thermoelectric generators. For a higher efficiency of the generators, shifting the temperature at which Bi2Te3 performs best to higher temperatures is required. Bipolar thermal conductivity suppression is the most effective approach to improve high-temperature thermoelectric performance. However, characterization of the bipolar thermal conductivity is challenging because it is related to individual contribution to Seebeck coefficient and electrical conductivity from the majority and minority carriers. Two-band model calculations are performed using reported band parameters of n-type Bi2Te3 to estimate the effects of band gap and minority to majority carrier concentration ratio in the bipolar thermal conductivity suppression. Individual Seebeck coefficient, electrical conductivity, and carrier concentrations from the majority and minority carriers are evaluated while varying chemical potential with a different band gap. It was demonstrated that increasing the band gap and chemical potential increased the individual Seebeck coefficient from minority carriers while decreasing the individual electrical conductivity and concentration from minority carriers. As a result, it was shown that the band gap increase and especially the magnitude of the minority to majority carrier concentration ratio decrease was effective in the bipolar thermal conductivity suppression.

Bi–Te-based alloys are potential candidates for use in thermoelectric (TE) modules for low-mid-temperature energy harvesting. However, n-type Bi–Te–Se alloys are inferior to their p-type counterparts in terms of TE performance. It has been found that doping Cu atoms into n-type Bi–Te–Se alloys is effective in improving the TE properties; however, different studies have reported contrasting roles of Cu dopants in the transport properties of Bi–Te–Se alloys. This is attributed to the complex doping behaviors of Cu atoms. In this study, it is demonstrated that employing an appropriate fabrication technique can enable more Cu dopants to be directed to specific atomic sites than others. As part of the study, two n-type polycrystalline Cu0.01Bi1.99Te2.7Se0.3 bulk samples are respectively fabricated via melt-spinning followed by spark plasma sintering, and via ball-milling followed by spark plasma sintering. The majority of Cu dopants in the melt-spun sample are suspected to exist in between Te1–Te1 atomic layers (van der Waals gap), given the elongated c-axis, increased Hall carrier concentration, and improved non-degenerate mobility (intercalated Cu generates one electron and acts as an electric connector). Resultantly, a ~30% enhancement in the TE figure-of-merit (~0.92 at 360–400 K) is achieved in the melt-spun sample, relative to the ball-milled sample, wherein Cu atoms substitute Bi atoms.

Abstract Background Gas forming infection of the spine is a consequence of vertebral osteomyelitis, necrotizing fasciitis, or a gas-forming epidural abscess, which is very rare and fatal conditions. This is the rare case of necrotizing fasciitis that rapidly progressed from the lumbar area to upper thoracic area. Case presentation A 58-year-old male complained of lower back pain with fever and chills. The patient had a history of uncontrolled diabetes mellitus without diabetic medication over the previous 3 months, and he had received several local injections around the lumbar area. Laboratory data revealed white blood cell count of 19,710 /mm3, erythrocyte sedimentation of 40 mm/h, and C-reactive protein of 30.7 mg/L. Radiological findings revealed a small amount of air bubbles in the paraspinal area and lumbar epidural spaces. The patient refused emergency surgery and was discharged from the hospital. The patient re-visited the emergency department two days after discharge complaining of more severe back pain with persistent fever, and his vital signs had deteriorated, with low blood pressure and tachycardia. K. pneumoniae was isolated in cultures from ultrasound-guided aspirates and peripheral blood. The follow-up radiographs revealed aggressive dissemination of innumerable air bubbles from the lumbar area to the T5 level. The patient underwent emergent decompressive laminectomy and debridement of infected paravertebral fascia and musculature. Despite intensive care for deteriorated vital signs and his back wound, the patient died on postoperative day 3 due to multi-organ failure. Conclusions Necrotizing fasciitis involving the spine is a very rare disease with life-threatening conditions, rapid progression, and a high mortality rate. Therefore, prompt surgical treatment with a high index of suspicion is imperative to prevent potentially fatal conditions in similar extremely rare cases.

Abstract Coagulopathy is frequent in septic shock and plays a key role in multiple organ dysfunction. The aim of this study is to investigate application values of thromboelastography (TEG) for outcome in septic shock patients with a normal value of prothrombin time (PT) and active partial thromboplastin time (aPTT). Prospective observational study using 1298 consecutive septic shock patients with TEG at admission was conducted at the emergency department (ED) of a tertiary care hospital in South Korea between 2016 and 2019. After excluding overt-disseminated intravascular coagulation (DIC) defined by scoring system, we included patients with a normal value of international normalized ratio ≤ 1.3 and aPTT ≤ 34 s. The primary outcome was 28-day mortality. 893 patients were included and 129 patients with overt DIC were excluded. Of the 764 remaining patients, 414 (54.2%) patients showed normal PT and aPTT (28-day mortality rate, 11.4%). TEG values such as reaction time, kinetic time (K), alpha angle (α), maximum amplitude (MA) and lysis index (LY 30) showed no significant mean difference between the survivor and non-survivor groups. However, hypocoagulable TEG values such as α 3 and α

We herein report the electronic and thermal transport properties of p-type Bi0.5Sb1.5Te3 polycrystalline bulks with dense pore structure. Dense pore structure was fabricated by vaporization of residual Te during the pressureless annealing of spark plasma sintered bulks of Te coated Bi0.5Sb1.5Te3 powders. The lattice thermal conductivity was effectively reduced to the value of 0.35Wm-1 K-1 at 300K mainly due to the phonon scattering by pores, while the power factor was not significantly affected. An enhanced ZT of 1.24 at 300K was obtained in spark plasma sintered and annealed bulks of 3wt.% Te coated Bi0.5Sb1.5Te3 by these synergetic effects. [ABSTRACT FROM AUTHOR]

Objective Rapid determination of acute coronary syndrome (ACS) in the emergency department (ED) is very important for patients presenting with ischemic symptoms. The aim of this study was to determine the predictive value of HEART score for ACS and significant coronary artery stenosis (SCS). Methods We retrospectively analyzed data of patients who visited the ED with chest discomfort and were admitted to the cardiology department. Enrolled patients were classified into ACS and non-ACS groups according to their discharge diagnosis. Patients who underwent imaging were further divided into SCS and non-SCS groups according to study results. We compared age, sex, vital signs, risk factors, electrocardiogram, troponin, and HEART score for each group. For ACS and SCS predictive performance, the test characteristics of HEART score was calculated using sensitivity, specificity, predictive value, likelihood ratio, and receiver operating characteristic (ROC) curve analysis. Results Of 207 patients, 112 had ACS. Among enrolled patients, 155 underwent imaging workup, of whom 67 had SCS. HEART score ≤3 had 93% sensitivity for ACS and 97% for SCS. HEART score ≥7 had 82% specificity for ACS and 83% for SCS. HEART score area under ROC curve for ACS was 0.706 (95% confidence interval, 0.627–0.776) and 0.737 (95% confidence interval, 0.660–0.804) for SCS. Conclusion HEART score was a fair predictor of ACS and SCS in ED patients who presented with chest symptoms and were admitted to the cardiology department. The predictive power of HEART score was better for SCS than for ACS.

Recently, the number of Corona Virus Disease 2019 (COVID-19) cases has increased remarkably in South Korea, so the triage clinics and emergency departments (ED) are expected to be overcrowded with patients with presumed infection. As of March 21st, there was a total of 8,799 confirmed cases of COVID-19 and 102 related deaths in South Korea that was one of the top countries with high incidence rates [1]. This sharp increase in infection is associated with 1) outbreaks in individual provinces, 2) deployment of rapid and aggressive screening tests, 3) dedicated healthcare staffs for virus screening tests, 4) quarantine inspection data transparency and accurate data reporting, and 5) public health lessons from previous Severe Acute Respiratory Syndrome (SARS) and Middle East Respiratory Syndrome (MERS) outbreaks. This commentary introduces innovative screening tests that are currently used in South Korea for COVID-19, e.g., Drive-Through and Walk-Through tests, and compare the advantages and disadvantages of both methods.

Controlling the electronic transport behavior in thermoelectric composites is one of the most promising approaches to enhance their power factor because this enables decoupling of the correlation between the electrical conductivity and Seebeck coefficient. Herein, we show that the unexpected high power factor of the Se nanowire array embedded in poly(3,4-ethylenedioxythiophene)-poly(styrenesulfonate) (PEDOT:PSS) can be achieved by controlling the interfacial band structure engineering. The electrical conductivity and Seebeck coefficient simultaneously increased, confirming that the synthesis of organic/inorganic hybrid thermoelectric materials with improved performance was possible. Our exploration can be helpful for the rational design of high-performance thermoelectric composites through interface engineering.

Some transition-metal dichalcogenides have been actively studied recently owing to their potential for use as thermoelectric materials due to their superior electronic transport properties. Iron-based chalcogenides, FeTe2, FeSe2 and FeS2, are narrow bandgap (~1 eV) semiconductors that could be considered as cost-effective thermoelectric materials. Herein, the thermoelectric and electrical transport properties FeSe2–FeS2 system are investigated. A series of polycrystalline samples of the nominal composition of FeSe2−xSx (x = 0, 0.2, 0.4, 0.6, and 0.8) samples are synthesized by a conventional solid-state reaction. A single orthorhombic phase of FeSe2 is successfully synthesized for x = 0, 0.2, and 0.4, while secondary phases (Fe7S8 or FeS2) are identified as well for x = 0.6 and 0.8. The lattice parameters gradually decrease gradually with S content increase to x = 0.6, suggesting that S atoms are successfully substituted at the Se sites in the FeSe2 orthorhombic crystal structure. The electrical conductivity increases gradually with the S content, whereas the positive Seebeck coefficient decreases gradually with the S content at 300 K. The maximum power factor of 0.55 mW/mK2 at 600 K was seen for x = 0.2, which is a 10% increase compared to the pristine FeSe2 sample. Interestingly, the total thermal conductivity at 300 K of 7.96 W/mK (x = 0) decreases gradually and significantly to 2.58 W/mK for x = 0.6 owing to the point-defect phonon scattering by the partial substitution of S atoms at the Se site. As a result, a maximum thermoelectric figure of merit of 0.079 is obtained for the FeSe1.8S0.2 (x = 0.2) sample at 600 K, which is 18% higher than that of the pristine FeSe2 sample.

Objective The quick sequential organ failure assessment (qSOFA) score, which includes mentation, systolic blood pressure, and respiratory rate, was developed to identify serious sepsis in out-of-hospital or emergency department (ED) settings. We evaluated the ability of the qSOFA score to predict poor outcome in South Korean ED patients with suspected infection. Methods The qSOFA score was calculated for adult ED patients with suspected infection. Patients who received intravenous or oral antibiotics in the ED were considered to have infection. In-hospital mortality rate, admission rate, intensive care unit (ICU) admission rate, length of hospital stay (LOS), and lactate levels were compared between the qSOFA score groups. Receiver operating characteristic curves and area under the receiver operating characteristic curve values for in-hospital mortality were calculated according to qSOFA cut-off points and lactate levels. Results Of 2,698 patients, in-hospital mortality occurred in 134 (5.0%). The mortality rate increased with increasing qSOFA score (2.2%, 6.4%, 17.5%, and 42.4% for qSOFA scores 0, 1, 2, and 3, respectively, P

In the wake of the pandemic of coronavirus disease 2019 (COVID-19), contact tracing has become a key element of strategies to control the spread of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). Given the rapid and intense spread of SARS-CoV-2, digital contact tracing has emerged as a potential complementary tool to support containment and mitigation efforts. Early modelling studies highlighted the potential of digital contact tracing to break transmission chains, and Google and Apple subsequently developed the Exposure Notification (EN) framework, making it available to the vast majority of smartphones. A growing number of governments have launched or announced EN-based contact tracing apps, but their effectiveness remains unknown. Here, we report early findings of the digital contact tracing app deployment in Switzerland. We demonstrate proof-of-principle that digital contact tracing reaches exposed contacts, who then test positive for SARS-CoV-2. This indicates that digital contact tracing is an effective complementary tool for controlling the spread of SARS-CoV-2. Continued technical improvement and international compatibility can further increase the efficacy, particularly also across country borders.

In this paper, the recursive form of an optimal finite impulse response filter is proposed for discrete time-varying state-space models. The recursive form of the finite impulse response filter is derived by employing finite horizon Kalman filtering with optimally estimated initial conditions. The horizon initial state and its error covariance on the horizon are optimally estimated by using recent finite measurements, in the sense of maximum likelihood estimation, then initiating the finite horizon Kalman filter. The optimality and unbiasedness of the proposed filter are proved by comparison with the conventional optimal finite impulse response filter in batch form. Moreover, an adaptive FIR filter is also proposed by applying the adaptive estimation scheme to the proposed recursive optimal FIR filter as its application. To evaluate the performance of the proposed algorithms, a computer simulation is performed to compare the conventional Kalman filter and adaptive Kalman filters for the gas turbine aircraft engine model.

The formation of secondary phases of NiTe2 and NbTe2 in p-type Bi0.5Sb1.5Te3 thermoelectric alloys was investigated through in situ phase separation by using the melt spinning process. Adding stoichiometric Ni, Nb, and Te in a solid-state synthesis process of Bi0.5Sb1.5Te3, followed by rapid solidification by melt spinning, successfully segregated NiTe2 and NbTe2 in the Bi0.5Sb1.5Te3 matrix. Since heterointerfaces of Bi0.5Sb1.5Te3 with NiTe2 and NbTe2 form potential barriers of 0.26 and 0.08 eV, respectively, a low energy carrier filtering effect can be expected; higher Seebeck coefficients and power factors were achieved for Bi0.5Sb1.5Te3(NiTe2)0.01 (250 μV/K and 3.15 mW/mK2), compared to those of Bi0.5Sb1.5Te3 (240 μV/K and 2.69 mW/mK2). However, there was no power factor increase for NbTe2 segregated samples. The decrease in thermal conductivity was seen due to the possible additional phonon scattering by the phase segregations. Consequently, zT at room temperature was enhanced to 0.98 and 0.94 for Bi0.5Sb1.5Te3(NiTe2)0.01 and Bi0.5Sb1.5Te3(NbTe2)0.01, respectively, compared to 0.79 for Bi0.5Sb1.5Te3. The carrier filtering effect induced by NiTe2 segregations with an interface potential barrier of 0.26 eV effectively increased the Seebeck coefficient and power factor, thus improving the zT of p-type Bi0.5Sb1.5Te3, while the interface potential barrier of 0.08 eV of NbTe2 segregation appeared to be too small to induce an effective carrier filtering effect.

Nanostructuring is considered one of the key approaches to achieve highly efficient thermoelectric alloys by reducing thermal conductivity. In this study, we investigated the effect of oxide (ZnO and SnO2) nanolayers at the grain boundaries of polycrystalline In0.2Yb0.1Co4Sb12 skutterudites on their electrical and thermal transport properties. Skutterudite powders with oxide nanolayers were prepared by atomic layer deposition method, and the number of deposition cycles was varied to control the coating thickness. The coated powders were consolidated by spark plasma sintering. With increasing number of deposition cycle, the electrical conductivity gradually decreased, while the Seebeck coefficient changed insignificantly; this indicates that the carrier mobility decreased due to the oxide nanolayers. In contrast, the lattice thermal conductivity increased with an increase in the number of deposition cycles, demonstrating the reduction in phonon scattering by grain boundaries owing to the oxide nanolayers. Thus, we could easily control the thermoelectric properties of skutterudite materials through adjusting the oxide nanolayer by atomic layer deposition method.

Polycrystalline bulks of Hf-doped Cu0.01Bi2Te2.7Se0.3 are prepared via a conventional melt-solidification process and subsequent spark plasma sintering technology, and their thermoelectric performances are evaluated. To elucidate the effect of Hf-doping on the thermoelectric properties of n-type Cu0.01Bi2Te2.7Se0.3, electronic and thermal transport parameters are estimated from the measured data. An enlarged density-of-states effective mass (from ~0.92 m0 to ~1.24 m0) is obtained due to the band modification, and the power factor is improved by Hf-doping benefitting from the increase in carrier concentration while retaining carrier mobility. Additionally, lattice thermal conductivity is reduced due to the intensified point defect phonon scattering that originated from the mass difference between Bi and Hf. Resultantly, a peak thermoelectric figure of merit zT of 0.83 is obtained at 320 K for Cu0.01Bi1.925Hf0.075Te2.7Se0.3, which is a ~12% enhancement compared to that of the pristine Cu0.01Bi2Te2.7Se0.3.

Herein we report a significantly reduced lattice thermal conductivity of Sb-doped Hf0.35Zr0.35Ti0.3NiSn half-Heusler alloys with sub-micron grains (grain size of ~300 nm). Polycrystalline bulks of Hf0.35Zr0.35Ti0.3NiSn1−xSbx (x = 0.01, 0.02, 0.03) with a complete single half-Heusler phase are prepared using temperature-regulated melt spinning and subsequent spark plasma sintering without a long annealing process. In these submicron-grained bulks, a very low lattice thermal conductivity value of ~2.4 W m−1 K−1 is obtained at 300 K due to the intensified phonon scatterings by highly dense grain boundaries and point-defects (Zr and Ti substituted at Hf-sites). A maximum thermoelectric figure of merit, zT, of 0.5 at 800 K is obtained in Hf0.35Zr0.35Ti0.3NiSn0.99Sb0.01.

The enhancement of electrical and optical properties in transparent conducting electrodes has attracted significant interest for their application in flexible electronic devices. Herein, a method for the fabrication of transparent conducting films is proposed. In this approach, RuO2 nanosheets are synthesized by a simple chemical exfoliation method and deposited as conducting films by repeated Langmuir–Blodgett coating. For enhancing the electrical and optical properties of the films, ultraviolet-ozone irradiation is applied between the repeated coatings for the removal of residual organic materials from the chemically exfoliated nanosheets. We observe that by applying ultraviolet-ozone irradiation for 30 min, the sheet resistance of the films decreases by 10% and the optical transmittance is simultaneously enhanced. Facile ultraviolet-ozone irradiation is shown to be an effective and industrially friendly method for enhancing the electrical and optical properties of oxide nanosheets for their application as transparent conduction electrodes.

Significant bipolar conduction of the carriers in Bi2Te3-based alloys occurs at high temperatures due to their narrow bandgaps. Therefore, at high temperatures, their Seebeck coefficients decrease, the bipolar thermal conductivities rapidly increase, and the thermoelectric figure of merit, zT, rapidly decreases. In this study, band modification of n-type Cu0.008Bi2(Te,Se)3 alloys by sulfur (S) doping, which could widen the bandgap, is investigated regarding carrier transport properties and bipolar thermal conductivity. The increase in bandgap by S doping is demonstrated by the Goldsmid−Sharp estimation. The bipolar conduction reduction is shown in the carrier transport characteristics and thermal conductivity. In addition, S doping induces an additional point-defect scattering of phonons, which decreases the lattice thermal conductivity. Thus, the total thermal conductivity of the S-doped sample is reduced. Despite the reduced power factor due to the unfavorable change in the conduction band, zT at high temperatures is increased by S doping with simultaneous reductions in bipolar and lattice thermal conductivity.

With the increasing penetration of renewable energy sources into modern power systems, parallel inverters with LCL filters are commonly employed in the grid interface, giving rise to potential resonance problems. Among the different resonances, interactive resonance is triggered by interaction among inverters when different current references are applied to parallel inverters. It may also feature a mutual current that circulates among inverters instead of flowing into the grid and introduces harmonics or instability in the control system. In this paper, active disturbance rejection control based on a reduced-order extended state observer (RESO) was proposed for parallel inverters. With the proposed scheme, the interaction between inverters is considered as an exogenous disturbance caused by other parallel inverters, estimated by the RESO, and rejected by the controller. In the results, the mutual current and interactive harmonics, calculated via fast Fourier transform, were reduced with the proposed control scheme. Thus, the lower total harmonic distortion of each current was achieved. Additionally, the robust stability and less model-dependent control design are the other additive advantages over the derivative filtered capacitor voltage feedforward-based active damping using PI control. The simulation and real-time experimental results of the conventional and proposed scheme, obtained using the hardware-in-loop, were presented to verify the theoretical analysis under the similar and different current reference cases.

Cation substitutional doping is an effective approach to modifying the electronic and thermal transports in Bi2Te3-based thermoelectric alloys. Here we present a comprehensive analysis of the electrical and thermal conductivities of polycrystalline Pb-doped p-type bulk Bi0.48Sb1.52Te3. Pb doping significantly increased the electrical conductivity up to ~2700 S/cm at x = 0.02 in Bi0.48-xPbxSb1.52Te3 due to the increase in hole carrier concentration. Even though the total thermal conductivity increased as Pb was added, due to the increased hole carrier concentration, the thermal conductivity was reduced by 14-22% if the contribution of the increased hole carrier concentration was excluded. To further understand the origin of reduction in the thermal conductivity, we first estimated the contribution of bipolar conduction to thermal conductivity from a two-parabolic band model, which is an extension of the single parabolic band model. Thereafter, the contribution of additional point defect scattering caused by Pb substitution (Pb in the cation site) was analyzed using the Debye-Callaway model. We found that Pb doping significantly suppressed both the bipolar thermal conduction and lattice thermal conductivity simultaneously, while the bipolar contribution to the total thermal conductivity reduction increased at high temperatures. At Pb doping of x = 0.02, the bipolar thermal conductivity decreased by ~30% from 0.47 W/mK to 0.33 W/mK at 480 K, which accounts for 70% of the total reduction. [ABSTRACT FROM AUTHOR]

Detecting high-risk (HR) HPV is important for clinical management of women with persistent HPV-positive and Pap-negative results. The Cobas 4800 HPV test is the first FDA-approved HPV DNA test that can be used alone as a first-line screening tool. The HPV 9G DNA chip test is a PCR-based DNA microarray assay. We evaluated the patients of consecutive HPV-positivity on HPV 9G DNA chip test without cytologic abnormalities. We then compared the performances of HPV 9G DNA chip and the Cobas 4800 HPV tests for detecting HR HPV with each other and confirmed HPV genotyping using direct sequencing. All 214 liquid-based cytology specimens were collected from 100 women with consecutive HPV-positive and Pap-negative results on the HPV 9G DNA chip test between May 2012 and Dec 2013, but only 180 specimens were available for comparing HPV test results. The HPV 9G DNA chip and the Cobas 4800 HPV tests agreed with each other in 81.7% of the samples, and the concordance rate was greater than 97.2% for detecting HPV-16 or -18. For HR genotypes other than HPV types 16 and 18, the two tests agreed for 81.1% of the samples. The sensitivity of both assays for detecting HR HPV was 100%, regardless of HR genotypes. The HPV 9G DNA chip test may be as effective as the Cobas 4800 HPV test in detecting HR HPV, and has a similar ability to identify HPV-16 and -18.

The prevalence of aac(6′)-Ib-crand its associated genes and mobile elements was investigated in Serratia marcescenscollected from 12 hospitals in Korea in 2005 and 2006. A total of 215 isolates (from 166 and 149 isolates collected in 2005 and 2006, respectively) were included in the study. Aac(6′)-Ib-crwas detected in only two isolates collected in 2005 and in 12 isolates collected from three hospitals in 2006. All 12 isolates carried class 1 integron and coharbored blaCTX-Mand armA. BlaOXA-1and ISCR1were detected in 10 and 8 isolates, respectively. All 12 isolates carried IncL/M type plasmid and 6 of them also carried IncA/C type plasmid. Conjugal transfer was successful for 9 of 12 aac(6′)-Ib-cr, all 12 blaCTX-M, 8 of 12 armA, and 6 of 10 blaOXA-1. Of the 12 transconjugants, IncL/M type plasmid, IntI1,ISEcp1, and ISCR1were detected in 12, 9, 12, and 8, respectively. The transferability of aac(6′)-Ib-cr, armA,and blaOXA-1was 100% for isolates harboring ISCR1, against 25%, 0%, and 0%, respectively, for isolates not harboring ISCR1. Both clonal and horizontal transfer were demonstrated by pulsed-field gel electrophoresis and plasmid profile analysis, respectively. Stringent infection control practices and further investigation of association between mobile elements and resistance genes are warranted. [ABSTRACT FROM AUTHOR]

Infectious complications are major causes of morbidity and mortality after liver transplantation, despite recent advances in the transplant field. Bacteria, fungi, viruses and parasites can cause infection before and after transplantation. Among them, bacterial infections are predominant during the first two months post-transplantation and affect patient and graft survival. They might cause surgical site infections, including deep intra-abdominal infections, bacteremia, pneumonia, catheter-related infections and urinary tract infections. The risk factors for bacterial infections differ between the periods after transplant, and between centers. Recently, the emergence of multi-drug resistant bacteria is great concern in liver transplant (LT) patients. The instructive data about effects of infections with extended-spectrum beta lactamase producing bacteria, carbapenem-resistant gram-negative bacteria, and glycopeptide-resistant gram-positive bacteria were reported on a center-by-center basis. To prevent post-transplant bacterial infections, proper strategies need to be established based upon center-specific data and evidence from well-controlled studies. This article reviewed the recent epidemiological data, risk factors for each type of infections and important clinical issues in bacterial infection after LT.