Search

This paper proposes a simple design scheme for a modular NPC inverter using thermal RC network analysis. The proposed design process is an efficient and straightforward approach to designing the heatsink for a 300 kW modular neutral-point-clamped inverter. The heatsink design plays a crucial role in achieving high power density of a power converter because the weight and size of the heatsink are primarily influenced by its type. The structure and dimensions of the heatsink are mainly determined based on the generated heat by losses of the power semiconductor switches. In this paper, a thermal RC network model was established using parameters from the power switch module and was applied to the simulation of the power converter. The thermal losses of the power semiconductor switches were calculated via this process, and the heatsink was designed according to the calculated thermal losses. The proposed design scheme was analyzed and compared with the thermal fluid dynamic model. To validate the feasibility of the proposed design process, The simulation results were compared with experimental results.

In this article, we propose a novel real-time threshold voltage ( $V_{th}$ ) compensation method for AM-OLED display. The proposed method predicts $V_{th}$ shift of driving thin-film transistors (TFTs) based on the equation derived from the sensing line charging with TFT’s drain current. The prediction equation requires two consecutive source node voltages to consider the mobility variation, and only takes hundreds of microseconds to predict $V_{th}$ shift. It is short enough to monitor the real-time $V_{th}$ degradation, since the prediction can be carried out during the vertical blank time. Also, very high prediction accuracy was confirmed through Smart SPICE simulation. We simulated severe mobility variation and $V_{th}$ shift circumstances, and the simulation results showed that the prediction error was less than one just noticeable difference (JND) margin though out all gray levels. We expect that the proposed method can achieve more accurate and faster real-time $V_{th}$ degradation compensation for high resolution and large-sized OLED displays than conventional one.

Sargassum horneri (SH) is a seaweed that has several features that benefit health. In this study, we investigated the immune-enhancing effect of SH, focusing on the role of spleen-mediated immune functions. Chromatographic analysis of SH identified six types of monosaccharide contents, including mannose, rhamnose glucose, galactose xylose and fucose. SH increased cell proliferation of primary cultured naïve splenocytes treated with or without cyclophosphamide (CPA), an immunosuppression agent. SH also reversed the CPA-induced decrease in Th1 cytokines. In vivo investigation revealed that SH administration can increase the tissue weight of major immune organs, such as the spleen and thymus. A similar effect was observed in CPA-injected immunosuppressed BALB/c mice. SH treatment increased the weight of the spleen and thymus, blood immune cell count and Th1 cytokine expression. Additionally, the YAC-1-targeting activities of natural killer cells, which are important in innate immunity, were upregulated upon SH treatment. Overall, our study demonstrates the immune-enhancing effect of SH, suggesting its potential as a medicinal or therapeutic agent for pathologic conditions involving immunosuppression.

The primo vascular system (PVS) is being established as a circulatory system that corresponds to acupuncture meridians. There have been two critical questions in making the PVS accepted as a novel liquid flowing system. The first one was directly to show the flow of liquid in PVS and the second one was to explain why it was not observed in the conventional histological study of animal tissues. Flow in the PVS in the abdominal cavity was previously verified by injecting Alcian blue into a primo node. However, the tracing of the dye to other subsystems of the PVS has not been done. In the current work we injected fluorescent nanoparticles (FNPs) into a primo node and traced them along a primo vessel which was inside a fat tissue in the abdominal wall. Linea alba is a white middle line in the abdominal skin of a mammal and a band of fat tissue is located in parallel to the linea alba in the parietal side of the abdominal wall of a rat. In this fat band a primo vessel runs parallel to the prominent blood vessels in the fat band and is located just inside the parietal peritoneum. About the second question on the reason why the PVS was not in conventional histological study the current work provided the answer. Histological analysis with hematoxyline and eosine, Masson's trichrome, and Toluidine blue could not discriminate the primo vessel even when we knew the location of the PVS by the trace of the FNPs. This clearly explains why the PVS is hard to observe in conventional histology: it is not a matter of resolution but the contrast. The PVS has very similar structure to the connective tissues that surround the PVS. In the current work we propose a method to find the PVS: Observation of mast cell distribution with toluidine blue staining and the PN has a high density of mast cells, while the lymph node has low density.

Several studies are conducted to explain the thermal decomposition mechanism associated with the various single-molecule precursors forming the metal sulfide nanoparticles. The amines are shown to play an extremely significant role in the thermolysis process.

Systematic graphite plate laser desorption/ionization time-of-flight mass spectrometry (GPLDI-TOF-MS) experiments along with gel permeation chromatography (GPC) measurements of polarization kinetics are employed. It is shown that the microstructure and polymerization of polyalkysilsesquioxanes depend strongly on the alkyl substituents, with the tendency to favor closed cage-type structures increasing with the size of the alkyl group.

The clinical and radiological outcomes of proximal tibia fractures involving the meta-diaphyseal junction treated with unilateral 3.5-mm locking precontoured anatomical plates are reported. Thirty-nine patients (41 proximal tibia fractures) who had proximal tibia fractures with complete meta-diaphyseal dissociation were enrolled in the study. For all patients, immediate postoperative and final follow-up simple radiographs were evaluated to determine the quality of the reduction by assessing coronal and sagittal alignment. In cases of intra-articular involvement, articular reduction quality and condylar width were additionally assessed. Clinical outcomes were assessed by knee range of motion and Lysholm knee score at final follow-up. Immediate postoperative radiographs showed satisfactory results: medial proximal tibial angle within 87°±5° in 87.8% (36 of 41), posterior tibia slope within 9°±5° in 85.4% (35 of 41), less than 2-mm articular step or gap in 79.3% (23 of 29), and a condylar width difference within 5 mm compared with the femoral condyles in 93.1% (27 of 29). All reductions but 1 were found to have satisfactory maintenance of the initial reduction. At final follow-up, the mean knee range of motion and Lysholm knee score were 122.5° (range, 100°-135°) and 75.8 (range, 50-100), respectively. A single lateral 3.5-mm plate fixation for proximal tibia fractures involving the meta-diaphyseal junction offers mechanically stable fixation with satisfactory clinical and radiological outcomes. [Orthopedics. 2018; 41(6):e777-e782.]. [ABSTRACT FROM AUTHOR]

The crystallization behavior has been studied in Zr62Al8Ni13Cu17 metallic glass alloy. The Zr62Al8Ni13Cu17 metallic glass crystallized through two steps. The fcc Zr2Ni phase transformed from the amorphous matrix during first crystallization and then the Zr2Ni and residual amorphous matrix transformed into a mixture of tetragonal Zr2Cu and hexagonal Zr6Al2Ni phases. Johnson-Mehl-Avrami analysis of isothermal transformation data suggested that the formation of crystalline phase is primary crystallization by diffusion-controlled growth. [ABSTRACT FROM AUTHOR]

Study Design: Retrospective case-control study.Objective: A cost-effectiveness analysis was performed by comparing patients who received extension revision operations for adjacent segment disease (ASD) reusing the pedicle screws extracted from fused segments with patients who received conventional surgery.Summary Of Background Data: ASD often required extension revision surgery, and during extension surgery, pedicle screws may be reused by extracting from the fused segments of primary surgery.Methods: Study examined 37 patients who received extension revision surgery for ASD from January 2003 to December 2013. For the fixation of extended segments during revision operation, in 16 cases the pedicle screws extracted from fused segments were reused (group R), and in 21 cases new pedicle screws were used (group C) as a conventional method. Clinical outcomes were evaluated by means of visual analog scale scores for lumbago and leg pain, and the Korean Oswestry Disability Index. Radiologic outcomes were evaluated from the extent of bone union. The total operating costs in the two groups were compared.Results: Visual analog scale scores for lumbago and leg pain, and the Korean Oswestry Disability Index measured at final follow-up averaged 3.6 and 3.8, and 19.9 in group R, and 3.8 and 3.1, and 21.1 in group C, respectively (P = 0.280, P = 0.387, P = 0.751). For radiologic outcomes, there was one case of nonunion in each group. The cost of surgery was 5332 US dollars in group R, and 6109 US dollars in group C, respectively (P = 0.036).Conclusion: Reusing pedicle screws extracted from the fused segments during extension revision operation for ASD can reduce the cost of surgery, and achieves clinical and radiological results similar to those of the conventional operation.Level Of Evidence: 4. [ABSTRACT FROM AUTHOR]

Background: We sought to evaluate the long-term outcomes of long-level instrumented posterolateral fusion (PLF) directly compared to those with short level instrumented PLF for degenerative spinal stenosis. Methods: From 1987-2002, patients who underwent instrumented PLF with wide decompression for degenerative spinal stenosis were reviewed. A total of 295 patients were available for follow-up over 10 years (mean, 14 years). These patients were divided into Group 1 (fusion of 1 or 2 levels) and Group 2 (fusion of three or more levels). Clinical and radiological outcomes were evaluated. Results: On clinical outcomes, Group 1 showed better results than Group 2 based on the Katz's Activities Daily Living index (p = 0.024), Kirkaldy-Willis criteria (p = 0.001) and the Korean version of the Oswestry disability index (p = 0.01). However, excellent and good outcome was noted in more than 64.5 % in Group 2. For radiological outcomes, overall fusion rate was higher in Group 1 compared with Group 2, but not significantly different (p = 0.35). However, the metal problems and surgical complications were more developed in Group 2 (p < 0.001). Although the radiologic changes on adjacent segments increased in accordance with the follow-up period, particularly in Group 2 (p < 0.001), no correlation with clinical symptoms was found. Conclusions: The long-level fusion group maintained acceptable clinical and radiological outcomes compared to the short-level fusion group at minimum of 10 years of follow-up. [ABSTRACT FROM AUTHOR]

Background: There is controversy about whether to retain or excise the posterior cruciate ligament in rheumatoid knees because attenuation of the ligament is often present in this subgroup of patients. We reviewed more than 15 years of results of cruciate- retaining total knee replacements (TKRs) in patients with rheumatoid arthritis. Methods: We reviewed patients' charts and radiographs to evaluate knee range of motion and flexion contractures, component loosening and osteolysis at the bone- cement interface. Our primary outcome was revision of a femoral or tibial component for any reason, and the secondary outcome was revision for any reason and periprosthetic fracture during the follow-up period. Results: Our study included 112 patients (7 men, 105 women, 176 knees). Their mean age was 49.3 (range 33-64) years. Twenty-one patients died and 16 were lost to followup, leaving 75 patients (119 knees) with a minimum follow-up of 15 (mean 16.1) years for our analysis. Of these, 61 patients (101 knees) were available for clinical and radiological evaluation at the final follow-up assessment. At a mean of 12.2 (range 6-16) years, revision was necessary in 14 patients (19 knees), including 1 patient with an infection. Eleven patients (11 knees) had periprosthetic fractures at a mean of 11.4 (range 5-14) years after the index operation. The survival rate, with the end point being revision of the femoral or tibial component for any reason, was 98.7% at 10 years and 83.6% at 17 years. The survival rate of revision and periprosthetic fracture was 97.6% at 10 years and 76.9% at 17 years. Conclusion: Special attention should be paid to component loosening or periprosthetic fracture after more than 10 years of follow-up in this subgroup of patients. [ABSTRACT FROM AUTHOR]

Purpose: The Korean Knee score (KKS) was designed to reflect the floor-sitting lifestyle that necessitates high knee flexion. The purpose of this study is to assess whether the KKS reflects the floor-sitting lifestyle more accurately than the previously developed Knee Society clinical rating system. In addition, the presence of ceiling effects was compared between the two rating systems. Materials and Methods: Eighty-one consecutive patients (120 knees) who were assessed regularly after total knee arthroplasty (TKA) on an outpatient basis between January 2012 and December 2012 were enrolled. All patients were asked to complete a questionnaire to assess the Knee Society Knee score (KSKS), Knee Society Function score (KSFS), and KKS. Results: At the final follow-up, the mean KSKS, KSFS, and KKS were 91.2, 86.0, and 70.1, respectively, and the scores were similar between the ≥125o maximum flexion group and <125o maximum flexion group. However, the ‘floor life’ subdomain score of the KKS was significantly higher in the >125o maximum flexion group (15.13 vs. 11.24, p=0.001). The number of cases with the highest possible score was 24 (20%) for the KSKS and 47 (39%) for the KSFS, whereas none of the cases obtained the highest possible KKS. According to the standard deviation method, more substantial ceiling effects were present in the KSKS (83 cases, 69.1%) and KSFS (67 cases, 55.8%) than in the KKS (23 cases, 19.2%). Conclusions: Although, the KKS was effective in reducing the ceiling effect, it demonstrated limited improvement in assessing the ability to perform high knee flexion after TKA. However, the ‘floor life’ subdomain of KSS appeared to be valid for evaluating high flexion of the knee. [ABSTRACT FROM AUTHOR]

Cerium-activated yttrium aluminate (Y3Al5O12:Ce3+) exhibiting a garnet structure has been widely utilized in the production of light emitting diodes (LEDs) as a yellow emitting phosphor. The commercialized yttrium aluminum garnet (YAG) phosphor is typically synthesized by a solid-state reaction, which produces irregular shape particles with a size of several tens of micrometers by using the top-down method. To control the shape and size of particles, which had been the primary disadvantage of top-down synthetic methods, we synthesized YAG:Ce nanoparticles with a diameter of 500 nm using a coprecipitation method under the atmospheric pressure without the use of template or special equipment. The precursor particles were formed by refluxing an aqueous solution of the nitrate salts of Y, Al, and Ce, urea, and polyvinylpyrrolidone (55 K) at 100 °C for 12 h. YAG:Ce nanoparticles were formed by the calcination of precursor particles at 1100 °C for 10 h under atmospheric conditions. The phase identification, microstructure, and photoluminescent properties of the products were evaluated by X-ray powder diffraction, scanning electron microscopy, absorption spectrum and photoluminescence analyses. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the influence of thigh weight in different hip flexion positions on the knee flexion gap in total knee arthroplasty (TKA). Materials and Methods: We evaluated 20 patients (25 knees) with osteoarthritis of the knee that underwent TKA using a navigation system from May 2010 to April 2011. After posterior cruciate ligament sacrificing, complete soft tissue balancing, and fixation of all components with cement, the flexion gaps were measured with the patello-femoral joint reduced. Medial and lateral flexion gaps were measured separately in both the 90o−90o and 45o−90o flexion positions of the hip-knee joints. Results: The medial and lateral flexion gaps in the 45o−90o flexion position of the hip-knee joints were 13.02±2.17 mm and 13.12±2.21 mm, respectively. The medial and lateral flexion gaps in the 90o−90o flexion position were 12.92±2.03 mm and 13.08±2.29 mm, respectively. The flexion gaps showed no significant (p>0.05) differences between the two different hip flexion positions. Conclusions: Flexion gaps in TKA were not influenced by hip flexion positions (45o or 90o of flexion). Therefore, soft tissue balancing and polyethylene thickness should not be affected by hip flexion positions during TKA. [ABSTRACT FROM AUTHOR]

The color tuning behavior and switching stability of an electrically tunable colloidal photonic crystal system were studied with particular focus on the electrochemical aspects. Photonic color tuning of the colloidal arrays composed of monodisperse particles dispersed in water was achieved using external electric field through lattice constant manipulation. However, the number of effective color tuning cycle was limited due to generation of unwanted ions by electrolysis of the water medium during electrical switching. By introducing larger electrochemical potential window electrodes, such as conductive diamond-like carbon or boron-doped diamond, the switching stability was appreciably enhanced through reducing the number of ions generated. [ABSTRACT FROM AUTHOR]

Fluorescent nanoparticles (FNPs) which were injected into a tumor tissue flowed out through the blood and lymph vessels. The FNPs in blood vessels remained only in the order for few minutes while those in lymph vessels remained for a long time disappearing completely in 25 hours. We found a primo vessel inside a lymph vessel near a blood vessel, and FNPs remained in the primo vessel for longer than 25 hours. In addition, we examined in detail the residual time characteristics of lymph vessels because it could be useful in a future study of fluid dynamical comparison of the three conduits. These residual time characteristics of FNPs in the three kinds of vessels may have implications for the dynamics of nanoparticle drugs for cancer chemotherapy [ABSTRACT FROM AUTHOR]

In this study, we developed a novel tool for purifying two mycotoxins, aflatoxin B1 (AFB1) and zearalenone (ZEN), in feed. This system utilized monoclonal antibodies (mAbs) against AFB1 and ZEN, and magnetic nanoparticles (MNPs). Among ten MNPs with different diameters and functional groups, a 100-nm diameter MNP (fMA) conjugated to an amine group (-NH2) was found to be optimum for coupling with mAbs. The optimal mAb concentrations for coupling to the fMA along with mycotoxin purification capacities of the fMA-mAb conjugates (fMA-AFB1 and fMA-ZEN) were determined. A comparison of mean recovery rates (from corn and product X feed) between the fMA-mAb conjugates and immunoaffinity columns (IAC-AFB1 and IAC-ZEN) showed that the rate for fMA-AFB1 (90~92% and 81~88%) was higher (p > 0.05) than that of IAC-AFB1 (81~84% and 72~78%) for AFB1 (5, 10, 15 ng/mL), and the rate for fMA-ZEN (99~100 % and 92~94%) was significantly higher (p < 0.01) than that of IAC-ZEN (86~88% and 81~88%) for ZEN (10, 25, 50 ng/mL) except at a concentration of 10 ng/mL, demonstrating the remarkable purification efficiency of the novel fMA-mAb method. Additionally, mycotoxin purification was much faster using our novel method (approx. 5 min) than the IAC-based technique ( > 30 min). This study suggests that the novel purification system we developed would be a useful tool for monitoring and regulating mycotoxin contamination in feed, and replace IAC methods. [ABSTRACT FROM AUTHOR]

Aminofunctional trialkoxysilanes such as aminopropyltrimethoxysilane (APTMS) and (3-trimethoxysilylpropyl)diethylenetriamine (DETAS) were employed as a surface modification molecule for generating monolayer modification on the surface of silica (SiO2) nanoparticles. We were able to quantitatively analyze the number of amine functional groups on the modified SiO2 nanoparticles by acid-base back titrationmethod and determine the effective number of amine functional groups for the successive chemical reaction by absorption measurements after treating with fluorescent rhodamine B isothiocyanate (RITC) molecules. The numbers of amine sites measured by back titration were 2.7 and 7.7 ea/nm2 for SiO2-APTMS and SiO2-DETAS, respectively, while the numbers of effective amine sites measured by absorption calibration were about one fifth of the total amine sites, namely, 0.44 and 1.3 ea/nm2 for SiO2-APTMS(RITC) and SiO2-DETAS(RITC), respectively. Furthermore, it was confirmed that the reactivity of amino groups on the surface-modified silica nanoparticles could be maintained in ethanol for more than 1.5 months without showing any significant differences in the reactivity. [ABSTRACT FROM AUTHOR]

The article provides information on a study that examines the incidence, pre- and postoperative risk factors and clinical results of postoperative delirium after spine surgery. The study found that there were significant relationships between postoperative delirium and comorbidity. It was also concluded that careful observation is necessary for the management of patients with risk factors of delirium.

The well-investigated method to prepare various nanoparticles is a thermolysis method in hot organic solutions. These nanoparticles are usually dispersible in nonpolar organic solvents, which sometimes causes problem to overcoat them with silica due to the polar alcoholic solvent in the silica forming process. We have developed a general procedure to incorporate high quality nanoparticles into silica beads. Organic-dispersible nanoparticles do not form precipitates in alcoholic solution in the presence of hydrophilic polyvinylpyrrolidone (PVP), and successive addition of TEOS with a basic catalyst can generate silica coating on nanocrystals. The PVP stabilized nanoparticles can also be easily adsorbed on the amino-functionalized silica bead surface to form interesting core-shell type structures. Many different nanoparticles from the thermolysis can be used in our preparation method, and these multifunctional silica nanocomposites are expected to be utilized in many applied fields where wettability, biocompatibility and ease of surface modification are very critical. [ABSTRACT FROM AUTHOR]

We report TiO2branched nanostructure photoelectrodes for dye-sensitized solar cells (DSSCs). The TiO2branch-type nanoparticle is synthesized by means of a seeding method with TiO2nanowire as a seed. During the seeding process, the TiO2nanostructure is evolved from a nanowire (NW) to nanobranch (NB) shape. It is also found that rutile TiO2-NB shows such a three-dimensional structure with branches grown along backbones of rutile TiO2-NW as confirmed by high-resolution transmission electron microscopy (HR-TEM) and X-ray diffraction (XRD) analysis. In photocurrent−voltage measurements, short-circuit current density, and cell efficiency of TiO2-NW and TiO2-NB increase from 6.25 to 12.18 mA/cm2and increase from 2.6 to 4.3%, respectively, due to both increased specific surface area and roughness factor. [ABSTRACT FROM AUTHOR]

Thermally stable vinyl polymerized polynorbornene (PNB) is one of the challenging materials in porous low dielectric films for packaging applications. Nanoporous PNB thin films were obtained with poly(d,l-lactide) (PLA)-grafted norbornene copolymers. Thermally labile PLA chains act as pore generators in PNB films. Thermally stable PNB main chains were synthesized by Pd-catalyzed vinyl polymerization and PLA side chains were grafted onto the PNB main chains by ring opening polymerization. The brittle and poor processible properties of PNB could easily be controlled by the copolymerization with norbornene derivatives. In thin films, the PLA chains were found to thermally decompose at about 250 °C while the PNB matrix was stable during this pore generating process. The porosity of the porous PNB thin films could be controlled up to 18% with pore sizes below 5 nm range by varying the chain length of grafted PLA. Introduction of cross-linking epoxy groups onto the PNB main chains resulted in the formation of well-defined nanopores without any extensive pore collapse during the vitrification of the PNB matrix. Additionally, it is demonstrated that the photopatterning of the thin films could be achieved using photoinitiator. [ABSTRACT FROM AUTHOR]