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In this work, body diode stress has been carried out for 1700 V 25 mΩ planar SiC MOSFETs. The epitaxial wafers were mapped with Infra-Red photoluminescence (IR-PL) to determine and localize the exact number of basal plane dislocations present in the drift layers of each die. The SiC MOSFETs were then packaged in groups with individual BPD counts in different bins ranging from 0 up to more than 30 per device. Pulsed body diode measurements with high currents of 250-400 A (about 1000-1600 A/cm2) were then performed with electrical characterization before and after to check for drift in key electrical parameters. Significantly increased RDSon was found after high current stress from about 300 A for devices with BPDs. A physical analysis of the degraded devices by backside electroluminescence show the presence of several trapezoid-shaped patterns indicating the occurrence of bipolar degradation.

The effect of alloying elements and microstructure on the dynamic strain aging (DSA) behavior of 1.25Cr-0.5Mo (P11, ASTM 335Gr.P11) and 2.25Cr-1Mo (P22, ASTM 335Gr.P22) steels was investigated. For both steels, different cooling conditions such as air-cooling (AC) and oil-quenching (OQ) were applied. Tensile tests were conducted in the temperature range of 20-450 ℃ and a strain rate in the range of 6 × 10-5- 6 × 10-3 s-1 for the steels with different cooling conditions. The P11AC steel showed serration behavior over a wider temperature range and exhibited higher ultimate tensile strength (UTS) than for the P22AC steel. This is attributed to the effects of alloying elements (Cr, Mo and Si) due to dissolved C, and the ferrite fraction on mechanical behavior. Meanwhile, the P11AC and P11OQ steels also showed different behaviors for DSA starting temperature, DSA temperature range, and serration type. The AC condition showed higher UTS from the interaction solid solution hardening (ISSH) effect due to substitutional Cr, Mo, and interstitial C elements. The calculated activation energy value (Q) for the P11 steel was around 94-103 kJ/mol-1, similar to that of ferritic steels, and it was higher for the P22 steel, with a Q value of 233 kJ/mol-1 from the ISSH effect.

Purpose: This study examined the effectiveness of action observation training (AOT) and mirror therapy in improving the electroencepha lograms (EEG) of stroke patients. Methods: Patients were allocated randomly to three groups: an action observation training with activity (AOTA) group (n=12), a mirror therapy with activity (MTA) group (n=11), and an AOT-only group (n=12). All groups received conventional physiotherapy in five 60-minute sessions over six weeks. The AOTA, MTA, and AOT groups practiced AOTA, MTA, and AOT, respectively, in three 30-minute ses sions over six weeks. The differences between the pre- and post-treatment EEGs were assessed using a paired t-test. Comparisons be tween the groups were performed using one-way ANOVA. Results: The participants in the AOTA and MTA groups showed significant improvement in the EEG. AOTA improved the alpha waves of the prefrontal, temporal, and parietal lobes significantly (p

Nanopillar compression tests were applied on δ-ferrites in austenitic stainless steel welds to measure the thermal ageing activation energy caused by spinodal decomposition. Welds of an austenitic stainless steel were thermally aged at 343, 375, and 400 oC for up to 20,000 h. To avoid the interference of surrounding austenite matrix on embrittlement measurement, austenite matrix was selectively dissolved before the nanopillar fabrication. Using the yield stress changes measured by nanopillar compression tests, the thermal ageing activation energy of δ-ferrite was estimated as 154 KJ/mol, which was compared with literature results and the reasons of discrepancy were discussed.

In this study, a new molecular design of thermally activated delayed fluorescence (TADF) emitters having a pyridine derived secondary acceptor was developed. Four TADF emitters were designed and synthesized to study the effect of the pyridine derived secondary acceptor on their TADF properties and device performances were investigated. The four TADF emitters, HPy, CNPy, CF3Py and CH3Py, with a pyridine secondary acceptor decorated by functional groups were developed as an approach to manage the emission wavelength and to improve efficiency roll-off characteristics of green TADF organic light-emitting diodes by decreasing the delayed fluorescence lifetime. The pyridine secondary acceptor based TADF emitters showed short delayed fluorescence lifetimes, and the TADF emitter with the methyl group functionalized pyridine secondary acceptor achieved a high external quantum efficiency (EQE) of over 20% and little efficiency roll-off up to 1000 cd m−2. Therefore, the pyridine secondary acceptor based molecular design was effective to manage the delayed fluorescence lifetime of the TADF emitters, and external quantum efficiency and efficiency roll-off of the TADF devices.

With the growing interest in human–electronics interaction, the development of ion gels that operate in response to variable human movement is widely spreading. However, conventional ion gels, based on hydrogel and non-hydrogel materials, have the fatal disadvantages of vulnerability to humidity and lack of transparency. Therefore, the need for an ion gel to satisfy all the requirements of elasticity, toughness, transparency, conductivity, and strong resistivity under humidity is emerging. Here, we demonstrate a polyvinylchloride (PVC)-based conductive ion gel with humidity-insensitive properties. To impart conductivity to the PVC gel, we use an ionic liquid. The prepared ion gel retains its elasticity with repeated tensile cycles of (200% strain) up to thirty times, and it exhibits ∼93% transparency and ∼40 kJ m−3 of toughness. In addition, excellent performance of this ion gel as a strain sensor was obtained, giving a conductivity increase with the factor of 100 compared with raw PVC gel. We show its application in human motion using a glove attached to the ion gel to monitor sign language and control a mouse pointer on the screen.

A novel design for thermally activated delayed fluorescence (TADF) emitters was developed by decorating dibenzofuran with four carbazole type electron donors and two CN electron withdrawing units. The four carbazole type donors were attached to one side of the dibenzofuran, and two CN units were introduced on the other side of the dibenzofuran for highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) separation. The HOMO and LUMO were largely separated, and they were overlapped in the dibenzofuran due to aromatic nature of dibenzofuran. Two TADF emitters, DBFCzCN and DBFtCzCN, were built on the design platform decorating the dibenzofuran, and they showed high EQEs of 25.2% and 17.4% in the vacuum deposited TADF devices. Additionally, the DBFtCzCN emitter showed a high EQE of 13.9% in the solution processed TADF devices.

Background: Face-lifting procedures are often performed to hide the effects of aging. Thread-lifting, a minimally invasive technique for the correction of facial aging, has become increasingly popular, and various materials for the procedure have been developed. Objective: This study compared tissue responses to two types of threading sutures placed under rat skin: polypropylene (PP) monofilament mesh suspension thread (a novel face-lifting material) and polydioxanone (PDO) barbed thread. Methods: Eight rats each were assigned to the PP monofilament mesh suspension, PDO barbed thread, and control groups. Tissue reactions were evaluated 28 days after subcutaneous loading of the materials. Results: Significant increases in tensile strength and the mean area occupied by collagen fibers were evident in skin loaded with PDO barbed thread and PP monofilament mesh suspension thread compared to control skin (p＜0.05). Compared to sites loaded with PDO barbed thread, those loaded with PP monofilament mesh suspension thread showed a significant increase in the number of collagen fibers and a lower grade of inflammation (p＜0.05). Conclusion: PP monofilament mesh suspension thread has skin-rejuvenating effects comparable to those of PDO barbed thread, but induces a less severe inflammatory response. This indicates that it is a safe and effective material for use in thread-lifting procedures on aging skin. (Ann Dermatol 31(6) 645∼653, 2019)

Recently, wearable triboelectric sensors capable of self-powering, which can be widely used in artificial skin and robotics, have received much attention. Herein, we develop a stretchable triboelectric pressure sensor with a new pattern by superimposing two patterns using both polystyrene beads and UV-ozone treatment. This patterned structure works more sensitively to pressure than a general planar and one-kind patterned structure. The sensor is constructed by sandwiching styrene butadiene rubber (SBR) and poly(dimethylsiloxane) (PDMS). It demonstrates a high sensitivity of 0.078 kPa-1 (0-20 kPa), a low detection limit (1.2 kPa), and pressure sensitivity maintained under 40% strain. The detection behavior of the strain-insensitive triboelectric sensor against pressure is very consistent with the simulation based on the theory. In applications, we successfully detect various human motions, not only small motions such as bending fingers but also large motions such as standing up and raising arms.

This study proposes an approach for process-focused assessment (PFA) utilizing the concept of deep neural networks with a sequence of facial images. Recently, process-based assessment has received significant attention compared to result-based assessment in the field of education. Continuously evaluating and quantifying student engagement, as well as understanding and interacting with teachers in study activities are considered important factors. However, to achieve PFA, from the technical and systematic perspectives, the real-time monitoring of the learning process of students is desired, which requires time consumption and extremely high attention to each student. This study proposes an approach to develop an efficient method for evaluating the process of learning and studying students in real time using facial images. We developed a method for PFA by learning facial expressions using a deep neural network model. The model learns and classifies facial expressions into three categories: easy, neutral, and difficult. Because the demand for online learning is increasing, PFA is required to achieve efficient, convenient, and confident assessment. This study chiefly considers a sequence of 2D image data of students solving some exam problems. The experimental results demonstrate that the proposed approach is feasible and can be applied to PFA in classrooms.

A lifetime extending molecular design approach by increasing the bond dissociation energy of the thermally activated delayed fluorescent (TADF) emitters was investigated. A TADF emitter with a molecular design having the donors in a planar manner, 4-(9H-carbazol-9-yl)-6-(9,9″-diphenyl-9H,9′H,9″H-[3,3′:6′,3″-tercarbazol]-9′-yl)isophthalonitrile (TCzIPN), was compared with state of the art green TADF emitter. The two emitters were green TADF emitters with similar peak wavelengths, but the TCzIPN exhibited three times longer lifetime than the current TADF emitter. Analysis of bond dissociation energy of the TADF emitters revealed that the weak C N bond of the TCzIPN was stabilized by small dihedral angle between donor and an aromatic linker. This was confirmed by exciton stability test of the emitters, and the C N bond stabilization effect in triplet excited state was well correlated with the lifetime improvement of the TCzIPN devices.

Nucleobindin 2 (NUCB2) has been reported to play an important role in both tumorigenesis and cancer progression. This study aimed to examine the clinical significance of NUCB2 expression urothelial carcinoma of the bladder (UCB). The expression level of NUCB2 and its correlation with clinicopathological parameters was analyzed in 225 UCB tissues by immunohistochemistry. Kaplan–Meier analysis and Cox proportional hazards regression models were used to investigate the correlation between NUCB2 expression and the prognosis of UCB patients. High NUCB2 expression of UCB patients significantly correlated with aggressive clinicopathological features. Patients with high NUCB2 had shorter overall survival and recurrence-free survival in Kaplan–Meier survival curve (P = .018 and P = .001, respectively). Our results show that high expression of NUCB2 associated with aggressive clinicopathological feature and predicted unfavorable prognosis in patients with UCB might serve as feasible biomarker for clinical outcome of UCB patients after surgery and potential therapeutic target in the future.

In the human skin, it has been well known that several mechanoreceptors uniquely sense external stimuli with specific frequencies and magnitudes. With regard to sensitivity, the output response shows nonlinearity depending on the frequency magnitude of the stimulus. We demonstrate a self-powered proton-driven solid-state somatosensor, which mimics a unique nonlinear response and intensity behavior of human mechanoreceptors. For this, a solid-state sensor is fabricated by combining a piezoelectric film and a proton generation device. The proton injection electrode and the Nafion layer conjugated with sulfonated graphene oxide are used for proton generation and transport. Two types of nonlinear signals from the sensor are similar to the Merkel/Ruffini (low deviation of threshold intensity), and in contrast, the behavior of Pacinian/Meissner (high deviation of threshold intensity) is simultaneously shown. The region of the most responsive frequency is also discriminated according to proton conduction. Moreover, it is asserted that unique signal patterns are obtained from the stimuli of various frequencies, such as respiration, radial artery pulse, and neck vibration, which naturally occur in the human body.

The effects of thermal aging on microstructure and mechanical property change of δ-ferrite in an austenitic stainless steel weld were investigated. After thermal aging at 400 °C for 20,000 h, spinodal decomposition and G phase precipitation were observed, along with ~80% increase in yield strength measured by nanopillar compression test. Subsequent reversion heat treatment removed spinodal decomposition while leaving G phase, resulting in partial recovery of hardening in δ-ferrite. It was estimated that ~60% of the hardening in the δ-ferrite of the aged specimen was attributed to spinodal decomposition and ~40% to G phase, respectively.

Cr-segregation by spinodal decomposition and G-phase precipitation were observed in δ-ferrite of austenitic stainless steel welds thermally aged at 400 °C for up to 20,000 h. A reversion heat treatment (R-HT) at 550 °C for 1 h dissolved the Cr-segregation in the aged welds while some intermetallic precipitates were present. The double-loop electrochemical potentiokinetic reactivation (DL-EPR) analysis showed no significant differences among them. However, after selective etching of the austenite phase, the DL-EPR values of δ-ferrite phase steadily increased with aging time due to the growth of Cr-depleted regions by spinodal decomposition. The electrochemical behavior of δ-ferrite after R-HT condition was similar to that of unaged welds, indicating the intermetallic precipitates did not affect the corrosion resistance in this case. Overall, DL-EPR analysis of δ-ferrite phase provided better correlation with spinodal decomposition.

Two types of Alloy 600 joints, such as diffusion-bonded joint and Alloy 182 fusion-weld, were exposed to supercritical-CO2 environment at 550 and 650 °C (20 MPa) for 1000 h. The diffusion-bond region showed similar oxidation characteristics as parent Alloy 600, but the migration of diffusion bond line below oxide layer was observed due to the Cr-depletion induced recrystallization. For Alloy 182 fusion-weld, outer Mn-rich oxides (Mn3O4 and MnCr2O4) and a small amount of inner SiO2 mixed with chromia were formed due to high Mn and Si contents. The presence of SiO2 in chromia suppressed carburization at the oxide/matrix interface, which resulted in the formation of an amorphous C layer between the outer Mn-rich oxide and inner Cr-rich oxide. For Alloy 182 fusion-weld, tensile property changes after exposure to supercritical-CO2 environment were negligible.

The device lifetime of the thermally activated delayed fluorescent (TADF) organic light-emitting diodes (OLEDs) was dramatically improved using a novel secondary acceptor based molecular design, while achieving high quantum efficiency of 18.5%. A series of TADF materials derived from a diphenyltriazine acceptor and a benzonitrile secondary acceptor were developed to study the effect of the secondary acceptor on the TADF parameters and device performances. The secondary acceptor simultaneously increased the bond dissociation energy in triplet excited state and the reverse intersystem crossing rate, which resulted in high external quantum efficiency, reduced efficiency roll-off, and lifetime extension. In particular, the lifetime was extended by more than 20 times, compared to that of the TADF emitter without the secondary acceptor. The correlation of the materials parameters with the lifetime of the green TADF OLEDs revealed that the bond dissociation energy and reverse intersystem crossing rate are well correlated with the device operational lifetime of the TADF OLEDs. Additionally, the secondary acceptor based TADF emitter outperformed the state-of-the-art green TADF emitter in terms of efficiency and lifetime. Optimization of the process condition of the device fabrication provided an extremely long lifetime of 532 h at 1000 cd/m2 up to 90% of initial luminance, which has not been previously achieved in the TADF devices.

The effect of dissolved hydrogen (DH) content and zinc addition on the corrosion behavior of type 316 stainless steel was investigated in the primary water environment of pressurized water reactors. The coupled effect, as well as the individual effect of increasing DH concentration and zinc addition, was investigated. Increasing DH from 25 (normal) to 50 (high) cc/kg-H2O resulted in 3 times thicker oxide layer. With the addition of 30 ppb zinc, the oxide layer became substantially thinner in both normal and high DH conditions. The measured electrochemical properties of oxide layers were in agreement with the observed corrosion behavior such that the zinc incorporated oxide film showed significant increase in reaction resistance and bode impedance value. Meanwhile, both reaction resistance and bode impedance slightly decreased with increasing DH concentration. Overall, the best corrosion resistance was observed in the simulated PWR environment with normal DH concentration and zinc addition.

Pure Ni and Ni-xCr (x = 7, 14, 22 and 27 wt%) binary alloys were exposed to supercritical-carbon dioxide environment at 600 °C and 20 MPa for 200 h. For pure Ni, a thick NiO layer was formed on the surface. Meanwhile, for Ni-7Cr alloy, an inner oxide layer consisted of rather irregular chromia and NiO was formed below the outer NiO layer. When Cr content was greater than 14%, a continuous chromia layer was formed, resulting in much lower weight gain and oxide thickness. However, amorphous carbon layers had developed along the oxide–matrix interface when chromia was formed. The presence of the carbon layer was explained in view of the high C activity corresponding to the low equilibrium oxygen potential of chromia.

Multi-layered SiC composites consisting of monolithic SiC and a SiC f /SiC composite are one of the accident tolerant fuel cladding concepts in pressurized light water reactors. To evaluate the integrity of the SiC fuel cladding under normal operating conditions of a pressurized light water reactor, the hydrothermal corrosion behavior of multi-layered SiC composite tubes was investigated in the simulated primary water environment of a pressurized water reactor without neutron fluence. The results showed that SiC phases with good crystallinity such as Tyranno SA3 SiC fiber and monolithic SiC deposited at 1200 °C had good corrosion resistance. However, the SiC phase deposited at 1000 °C had less crystallinity and severely dissolved in water, particularly the amorphous SiC phase formed along grain boundaries. Dissolved hydrogen did not play a significant role in improving the hydrothermal corrosion resistance of the CVI-processed SiC phases containing amorphous SiC, resulting in a significant weight loss and reduction of hoop strength of the multi-layered SiC composite tubes after corrosion.

Autophagy, one mechanism of programmed cell death, is fundamental to cellular homeostasis. Previous studies have identified autophagy as a novel mechanism by which cytokines control the immune response. However, its precise role in immune-related inflammatory skin diseases such as psoriasis remains unclear. Thus, this study explored the functional role of autophagy in psoriatic inflammation of epidermal keratinocytes. Strong light chain 3 immunoreactivity was observed in epidermal keratinocytes of both human psoriatic lesions and imiquimod-induced mice psoriatic model, and it was readily induced by polycytidylic acid (poly (I:C)), which stimulates Toll-like receptor 3 (TLR3), in human epidermal keratinocytes in vitro. Rapamycin-induced activation of autophagy significantly reduced poly (I:C)-induced inflammatory reaction, whereas, inhibition of autophagy by 3-methyladeine increased that. Our results indicate that the induction of autophagy may attenuate TLR3-mediated immune responses in human epidermal keratinocytes, thus providing novel insights into the mechanisms underlying the development of inflammatory skin diseases including psoriasis.

An austenitic stainless steel weld was thermally aged at 400 °C for 20,000 h, and subsequently proton irradiated up to 10 displacement per atom (dpa) at 360 °C. After thermal ageing, only spinodal decomposition was observed without G-phase precipitates in δ-ferrite. However, ~ 1023 m−3 of fine (~ 3 nm in diameter) G-phase precipitates were observed after proton irradiation. Also, wavelength of spinodal decomposition was increased with proton irradiation. The additional hardening in δ-ferrite after proton irradiation was attributed to enhanced spinodal decomposition and G-phase precipitation. After irradiation, the contribution to addition hardening was greater for G-phase than enhanced spinodal decomposition.

In order to improve the corrosion and carburization resistance in a high-temperature supercritical-carbon dioxide (S-CO2) environment, an Al-rich surface layer was developed on Alloy 600 by Al deposition and a subsequent high energy electron beam (EB) remelting. As a result of the EB surface treatment, an Al enriched (5–7 wt.%) micro-alloying zone (40 μm) was produced. When the EB surface-treated Alloy 600 was corroded in S-CO2 at 600 °C (20 MPa) for 500 h, the surface oxide layer mostly consisted of chromia (Cr2O3) with small amount of transition alumina (Al2O3). In addition, a carburized region of an amorphous C layer inter-mixed with the alumina was observed at the oxide/matrix interface. Meanwhile, when the EB surface-treated specimen was pre-oxidized in helium at 900 °C, α-alumina layer was formed on the surface, which showed superior corrosion and carburization resistance in S-CO2 environment. Therefore, it could be said that the presence of Al-rich surface layer alone is not enough to provide sufficient corrosion and carburization resistance in S-CO2 environment at 600 °C, unless pre-oxidation at higher temperature is applied to form a more protective α-alumina on the surface.

A dual-process coating structure was developed on a graphite substrate to improve the performance of the coating structure under anticipated operating condition of fusion devices. A thin multilayer W/Mo coating (6 μm) was deposited by physical vapor deposition (PVD) method with a variation of Mo interlayer thickness on plasma spray (PS) W coating (160 μm) of a graphite substrate panel. The dual-process PVD/PS W coatings then were exposed to 3.08 × 1024 D m−2 of 100 eV D ions with a flux of 1.71 × 1021 D m−2 s−1 in an electron cyclotron resonance (ECR) chamber. After irradiation, surface morphology and D depth profiles of the dual-process coating were analyzed and compared to those of the simple PS W coating. Both changes in surface morphology and D retention were strongly dependent on the microstructure of surface coating. Meanwhile, the existence of Mo interlayer seemed to have no significant effect on the retention of deuterium.

Various tungsten (W) coating techniques have been used for the application of plasma facing material in nuclear fusion devices, which resulted in limited success. In this study, a dual-process W coating structure was developed on a graphite substrate to improve the thermal performance of the coating structure. The dual-process coating structure consisted of a thin (∼7 μm) multilayer W/Mo physical vapor deposition (PVD) coating layer deposited on top of the relatively thick (∼160 μm) plasma spray (PS) W coating on a graphite substrate panel. Then the coated sample was exposed to plasma heat flux of 1–3 MW/m2 for 300 s. With addition of a thin surface PVD coating layer, the microstructure change in underlying PS W coating was substantially reduced compared to the simple PS W coating structure. The thickness of overall coating structure was maintained for the dual-process PVD/PS coated samples after the thermal loading tests, while a significant reduction in thickness due to surface erosion was observed for the simple PS W coated samples. The improvement in surface erosion resistance in the dual-process coating structure was discussed in view of the characteristics of PVD and PS coating layers.

Chromia-forming heat-resistant alloys were corroded in atmospheric CO2 (0.1 MPa) and supercritical-CO2 (S-CO2, 10 and 20 MPa) at 550–650 °C for 1000 h. The weight gain and the extent of an amorphous C layer at the oxide/matrix interface increased with increasing CO2 pressure from 0.1 MPa to 20 MPa, but the increase was mostly less than a factor of 2. Despite the huge difference in the test pressure, the depth of the carburized region with Cr-rich carbides was rarely affected for Alloy 800HT, resulting in similar tensile properties after corrosion in CO2 and S-CO2.

C compilers for 8-bit MCUs used in washing machines and refrigerators often do not follow the C standard to improve runtime performance. Developers who are unaware of the difference between C compilers following the C standard and the C compilers for 8-bit MCU can cause bugs that do not appear in the standard C environment but appear in the embedded systems using 8-bit MCUs. It is difficult for bug detectors that assume the standard C environment to detect such bugs. In this paper, we introduce integer promotion bugs caused by the different integer promotion rules of the C compilers for 8-bit MCU from the C standard and propose 5 bug patterns where the integer promotion bugs occur. We have developed an integer promotion bug detection tool and applied it to the washing machine control software developed by the LG electronics. The integer promotion bug detection tool successfully detected 27 integer promotion bugs in the washing machine control software.

Primary squamous cell carcinoma (SCC) of the stomach is a very rare disease. However, the pathogenesis, clinical characteristics, and prognosis of gastric SCC are controversial and remain to be elucidated. Herein, we report a case of primary gastric SCC of the remnant stomach after subtotal gastrectomy. A 65-year-old man was admitted to our hospital due to epigastric discomfort and dizziness. He had undergone subtotal gastrectomy 40 years previously for gastric ulcer perforation. Endoscopy revealed a normal esophagus and a large mass in the remnant stomach. Abdominal computed tomography revealed enhanced wall thickening of the anastomotic site and suspected metachronous gastric cancer. Endoscopic biopsy revealed SCC. Total gastrectomy was performed with Roux-en-Y esophagojejunostomy. A 10-cm tumor was located at the remnant stomach just proximal to the previous area of anastomosis. Pathologic examination showed well-differentiated SCC extended into the subserosa without lymph node involvement (T3N0M0). The patient received adjuvant systemic chemotherapy with 6 cycles of 5-FU and cisplatin regimen, and he is still alive at the 54-month follow-up. According to the treatment principles of gastric cancer, early detection and radical surgical resection can improve the prognosis.

Model alloys and thermomechanical processing (TMP) were developed to form a high density of uniformly distributed nanosized (

Background: Psoriasis is a multifactorial disease associated with an increased risk for metabolic syndrome and cardiovascular diseases. Elevated levels of homocysteine (Hcy) are a marker of cardiovascular risk. Several studies have evaluated the associations between psoriasis and Hcy levels; however, the results remain inconclusive. Objective: We performed a systematic review of the literature and a meta-analysis to better understand the relationship between psoriasis and Hcy. Methods: Five scientific databases (MEDLINE, Embase, Cochrane Library, Scopus, and Web of Science) were searched to identify relevant studies. A review of 307 publications identified 16 studies that directly assessed plasma levels of Hcy in psoriasis patients. Results: A total of 16 studies including 2,091 subjects were included in the meta-analysis. Hcy levels were significantly higher in psoriasis patients relative to healthy controls (weighted mean difference [WMD], 3.30; 95% confidence interval [CI], 1.58∼ 5.02; I2=82.1%). Subgroup analyses revealed that patients with higher mean psoriasis area severity index (PASI) scores (PASI＞10) had significantly higher Hcy levels compared to healthy controls (WMD, 4.17; 95% CI, 1.18∼7.16; I2=88.3%), whereas patients with lower mean PASI scores (PASI ≤10) had not (WMD, 0.76; 95% CI, -1.84∼3.35; I2=72.2%). Conclusion: This meta-analysis found that psoriasis patients, in particular those with PASI ＞10, had significantly higher Hcy levels compared to healthy controls. Further research is needed to determine the association between Hcy levels and psoriasis severity. (Ann Dermatol 31(4) 378∼386, 2019)