Search

Yttria-stabilized zirconia (YSZ) and Al₂O₃ multilayer coatings were fabricated by plasma spraying. Thermal conductivity and thermal shock test were investigated to find out the thermal properties of the coating layer and the surface of the crack. Thermal conductivity was investigated using laser flash method and thermal shock were measured by water quenching method. Furthermore, the factors influencing thermal properties of these coatings were analyzed in detail. Multilayer coatings have imperfect interfaces. At an imperfect interface, the heat transfer coefficient was close to zero, indicating a low thermal conductivity. Multilayer coatings increase thermal shock resistance. This is because ZrO₂ phases transformation from tetragonal to monoclinic occurring to the cooling process, resulting in microcracks due to volume expansion. The crack generated at this time dispersed and absorbed the thermal shock, so that it exhibited excellent thermal shock resistance.

OBJECTIVE: To investigate the duration and peak of severe acute respiratory syndrome coronavirus 2 shedding as infectivity markers for determining the isolation period. METHODS: A total of 2,558 upper respiratory tract (URT) and lower respiratory tract (LRT) specimens from 138 patients with laboratory-confirmed coronavirus disease were analyzed. Measurements of sequential viral loads were aggregated using the cubic spline smoothing function of a generalized additive model. The time to negative conversion was compared between symptom groups using survival analysis. RESULTS: In URT samples, viral RNA levels peaked on day 4 after symptom onset and rapidly decreased until day 10 for both E and RdRp genes, whereas those in LRT samples immediately peaked from symptom onset and decreased until days 15.6 and 15.0 for E and RdRp genes, respectively. Median (interquartile range) time to negative conversion was significantly longer in symptomatic (18.0 [13.0-25.0] days) patients than in asymptomatic (13.0 [9.5-17.5] days) patients. The more types of symptoms a patient had, the longer the time to negative conversion. CONCLUSIONS: The viral load rapidly changes depending on the time after symptom onset; the viral shedding period may be longer with more clinical symptoms. Different isolation policies should be applied depending on disease severity.

Yttria-stabilized zirconia (YSZ) and Al₂O₃ multilayer coatings were fabricated by plasma spraying. Thermal conductivity and thermal shock test were investigated to find out the thermal properties of the coating layer and the surface of the crack. Thermal conductivity was investigated using laser flash method and thermal shock were measured by water quenching method. Furthermore, the factors influencing thermal properties of these coatings were analyzed in detail. Multilayer coatings have imperfect interfaces. At an imperfect interface, the heat transfer coefficient was close to zero, indicating a low thermal conductivity. Multilayer coatings increase thermal shock resistance. This is because ZrO₂ phases transformation from tetragonal to monoclinic occurring to the cooling process, resulting in microcracks due to volume expansion. The crack generated at this time dispersed and absorbed the thermal shock, so that it exhibited excellent thermal shock resistance.

Conjunctival swelling is a common finding in patients positioned prone. The purpose of this study was to evaluate the effect of head position on postoperative chemosis after prone spinal surgery. On the basis of the head position, 108 patients scheduled for prone lumbar surgery were randomly allocated to 1 of 2 groups: head neutral group (n=54) versus head down (HD) group (n=54). Head position was defined as neutral when the imaginary line from the occipital protuberance to the top of C7 spine process is parallel to the operating table. HD position was maintained by adjusting the height of the prone headrest 5 cm lower than neutral position. Chemosis was evaluated after surgery. The severity of chemosis, which was graded as none, mild, moderate, and severe, showed statistically significant difference between the head neutral group [24 (44%), 25 (46%), 3 (6%), 2 (4%), respectively] and HD group [10 (19%), 23 (43%), 17 (31%), 4 (7%), respectively, P

Lycopene, the predominant carotenoid in tomatoes and tomato-based foods, is reported to protect against various cancers, especially prostate cancer. We investigated the effect of lycopene on DNA damage and cell growth inhibition in the Hep3B human hepatoma cell line. Lycopene was analyzed by HPLC, and cell proliferation was determined by 3-(4,5-dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide (MTT) assay. A final lycopene concentration of 0.1-50 microM was added to cells plated in 96-well plates. After a 24-hr incubation, cell viability was measured as absorbance at 570 nm after the MTT assay. The effects of lycopene on cell cycle progression were investigated with flow cytometry. Lycopene induced G0/G1 arrest and S phase block. Oxidative DNA damage was determined by the Comet (single-cell gel electrophoresis) assay. Lycopene inhibited cell growth in a dose-dependent manner. Cell growth was inhibited 20% at 0.2 microM lycopene and 40% at 50 microM lycopene after a 24-hr incubation. In the Comet assay, lycopene-treated cells showed less DNA damage than did placebo-treated cells. The inhibition of Hep3B cell growth in this study demonstrates the antitumor properties of lycopene.

A new DDLC (density dependent local composition) model which possesses sound theoretical background describing both size and energy asymmetries of molecules has been developed. Dividing the radial distribution function into packing and attractive effects new local composition model naturally satisfies high and low density boundary conditions and it shows desirable characteristics to represent computer simulated local composition data correctly. Based on the new local composition model, DDLC mixing rule for the cubic equation of state has been derived and utilized to calculate the solubilities of solids in supercritical fluid mixtures. It has been found that new version of DDLC mixing rule shows excellent capabilities to predict solubilities of solids in various supercritical fluid systems including solid mixtures or entrainers.

The existing encoding scheme for LDPC codes usually incurs too high complexity and should be changed to a low complexity encoding scheme. However, little consideration has been given to the LDPC encoder VLSI implementation. We consider low complexity encoding of regular LDPC codes, and we propose a pivoting and bit-reverse (PABR) algorithm to rapidly construct the parity-check matrix (PCM). And we consider improved regular LDPC codes in BER performance. We propose that the PCM is constructed with sub-matrixes which are made up of Costas arrays. The codes have sparse PCMs. They are designed to perform well when iteratively decoded with the sum-product decoding algorithm and to allow low complexity encoding. We show an approach to implementing the LDPC encoder using the PABR algorithm and improving BER performance using a PCM with Costas arrays. This paper then describes an FPGA implementation of regular LDPC encoder on a hardware platform for 4G mobile communication systems.

We consider in this paper the encoding problem for low-density parity-check (LDPC) code. We investigate an efficient encoding approach for LDPC code. The straightforward the existing encoding scheme for LDPC code usually incurs too high complexity and should be changed to encoding scheme with low complexity. However, little consideration has been given to the LDPC encoder VLSI implementation. We consider low complexity encoding of regular LDPC code, and we propose a pivoting and bit-reverse (PABR) algorithm to rapidly construct parity-check matrix for regular LDPC code. The code have sparse parity-check matrix. They are designed to perform well when iteratively decoded with the sum-product decoding algorithm and to allow low complexity encoding. Performance is superior to that of cyclic regular LDPC code can be achieved. We show approach to implementing LDPC encoder using PABR algorithm. This paper then describes FPGA implementation of regular LDPC encoder on hardware platform for 4th mobile communication system.

The Vital capacity technique is known to have some advantages over the tidal volume technique during inhalation induction of anesthesia.The aim of this study was to compare the incidence of withdrawal movement associated with the intravenous administration of rocuronium 0.3 mg/kg in children during inhalation induction with sevoflurane using the tidal volume and vital capacity techniques. Methods:We randomly assigned 130 patients (aged 5－12 years) to either tidal volume (group T) or vital capacity (group V) groups for inhalation induction with sevoflurane.Rocuronium 0.3 mg/kg was administrated after loss of the eyelash reflex.The time to loss of the eyelash reflex was recorded and adverse events during induction were documented.The patient’s response to rocuronium injection was graded using a four-point scale. Results:No significant differences were observed between the groups with respect to age, weight, and gender.The time to loss of the eyelash reflex was more rapid in group V than in group T (P ＜ 0.05).Excitatory movement developed more frequently in group T, and no significant differences were found in the incidence of other adverse events between the groups.The incidence of withdrawal movement associated with the injection of rocuronium was significantly lower in group V compared to group T (30 vs. 60%; P ＜ 0.05). Conclusions:Inhalation induction with sevoflurane using the vital capacity technique decreased the incidence of withdrawal movement during the injection of rocuronium compared to the tidal volume technique.

Background: Hydromorphone, a derivative of morphine, has the same actions and uses as morphine, has about eight times more potency on a milligram basis. Hydromorphone is used for the relief of moderate to severe pain. There has been no report in Korea on patient controlled analgesia (PCA) using hydromorphone. Here, the efficacy and incidence of side effects of PCA, with hydromorphone, were investigated. Methods: 68 patients scheduled for spinal, urological, gynecological and general surgery were enrolled. Patients received standardized general anesthesia, with the PCA initiated at the end of surgery. Parameters for PCA were a 0.1 mg bolus and 0.05 mg/hr infusion of hydromorphone, with a 10 min lockout interval. A verbal rating scale (1: none, 2: very mild, 3: mild, 4: moderate, 5: severe) of pain, nausea (mild, moderate, severe), vomiting, dizziness and somnolence were assessed at 6, 12, 24 hr postoperatively. The amount of hydromorphone used and the requirements for symptomatic relief were also recorded. Results: The mean pain scores were 3.5 0.8, 2.9 0.8 and 2.5 0.7, and the amounts of hydromorphone delivered were 1.0 0.1, 1.8 1.0 and 2.7 1.3 mg, 6, 12 and 24 hr postoperatively, respectively. The incidence of nausea, vomiting, dizziness and somnolence were 17.6, 4.4, 8.8 and 1.5%, respectively. Conclusions: Intravenous PCA, with hydromorphone, was effective in controlling postoperative pain, with fewer eide effects than morphine, as reported in the literature.