The Experts below are selected from a list of 117 Experts worldwide ranked by ideXlab platform

Ho Jang - One of the best experts on this subject based on the ideXlab platform.

  • effects of Antimony Trisulfide sb2s3 on sliding friction of automotive brake friction materials
    Metals and Materials International, 2013
    Co-Authors: Wan Kyu Lee, Tae Hee Rhee, Hyun Seong Kim, Ho Jang
    Abstract:

    The effect of Antimony Trisulfide (Sb2S3) on the tribological properties of automotive brake friction materials was investigated using a Krauss type tribometer and a 1/5 scale dynamometer with a rigid caliper. Results showed that Sb2S3 improved fade resistance by developing transfer films on the disc surface at elevated temperatures. On the other hand, the rubbing surfaces of the friction material exhibited contact plateaus with a broader height distribution when it contained Sb2S3, indicating fewer contact junctions compared to the friction material with graphite. The friction material with Sb2S3 also exhibited a lower stick-slip propensity than the friction material with graphite. The improved fade resistance with Sb2S3 is attributed to its lubricating capability sustained at high temperatures, while the lower stick-slip propensity of the friction material with Sb2S3 is associated with the slight difference between its static and kinetic coefficients of friction and high normal stiffness.

  • compositional effects of the brake friction material on creep groan phenomena
    Wear, 2001
    Co-Authors: Ho Jang, J. S. Lee, J W Fash
    Abstract:

    Abstract Creep groan (low frequency frictional vibration in the range of 200–500 Hz during braking at a very low vehicle speed) was studied by changing the relative amounts of ingredients in a brake friction material containing 12 ingredients. Twenty-nine friction material specimens with different relative amounts of the ingredients were manufactured according to a constrained mixture design. The difference (Δ μ ) between kinetic ( μ k ) and static ( μ s ) coefficients of friction for each formulation was measured to investigate creep groan propensity of each friction material since the creep groan is caused by stick–slip phenomena. Results showed that zircon (zirconium silicate), steel wool, and phenolic resin showed a tendency to increase Δ μ . On the other hand, Antimony Trisulfide, cashew particles, and rockwool tended to reduce Δ μ . Based on the results of this work, the initial formulation was modified to reduce Δ μ . The modified friction material showed a smaller Δ μ value than the initial friction material implying low propensity of creep groan phenomena during braking. The velocity dependence of the friction coefficient was also examined using the initial and the modified friction materials. The modified formulation exhibited a less negative μ – V relation than the initial formulation.

  • the effects of Antimony Trisulfide sb2s3 and zirconium silicate zrsio4 in the automotive brake friction material on friction characteristics
    Wear, 2000
    Co-Authors: Ho Jang, Seong Ji Kim
    Abstract:

    Abstract Friction characteristics of nine automotive brake friction materials containing different amounts of Antimony Trisulfide (Sb2S3) and zirconium silicate (ZrSiO4) were investigated by using a brake dynamometer. Two different modes of brake applications (drag mode and stop mode) were employed to study the change of friction coefficient and torque variation (friction force oscillation). Results showed that the relative amount of Sb2S3 and ZrSiO4 played important roles in determining the friction characteristics. Sb2S3 in the friction material improved the friction stability and ZrSiO4 aggravated the torque variation during brake applications.

Seong Ji Kim - One of the best experts on this subject based on the ideXlab platform.

Chris Tsopelas - One of the best experts on this subject based on the ideXlab platform.

  • lymphoscintigraphy is more effective using higher specific activity 99m tc Antimony Trisulfide colloid in the rat
    Hellenic Journal of Nuclear Medicine, 2014
    Co-Authors: Chris Tsopelas
    Abstract:

    Technetium-99m-Antimony Trisulfide colloid ((99m)Tc-ATC) was investigated with varying specific activity in the rat lymphatic system, as well as its binding to rat blood cells in vitro. Low, moderate and high doses of (99m)Tc-ATC were subdermally injected into tails of rats (n=3) and 30min later whole body lymphoscintigraphic images were acquired. (99m)Tc-ATC was incubated for 30min at 37°C with whole blood (n=4) as for control, at 4°C as for hypothermia, as opsonized at 37°C and lipopolysaccharide (LPS) at 37°C. Cell types were separated by gradient centrifugation to assay for cell bound-radioactivity. These experiments were repeated using mixed leukocytes that were erythrocytes-free. Images showed direct drainage of (99m)Tc-ATC from the tail to the popliteal nodes, sacral node and beyond, along the para-aortic chain, and to a left inguinal lymph node that drained into the axillia. The higher specific activity dose resulted in more visible lymph nodes after 30min. (99m)Tc-ATC was predominantly not cell-bound. In rat whole blood (99m)Tc-ATC-neutrophils were only present to the extent of 3% for the control, 3% for the hypothermia test, 4% for the opsonized and 7% for the LPS test. In the erythrocytes-free samples, (99m)Tc-ATC-leukocytes were present to the extent of 5% (control), 4% (hypothermia), 6% (opsonized) and 11% (LPS). In conclusion, a higher specific activity radiocolloid may identify the sentinel lymph node sooner during lymphoscintigraphy, and there may be an advantage in detecting more counts with the γ-probe. Retention of (99m)Tc-ATC in lymph nodes in vivo is likely because of binding on macrophage surfaces, rather than from internalization by phagocytosis within a time frame of 30min after injection.

  • particle size analysis of 99mtc labeled and unlabeled Antimony Trisulfide and rhenium sulfide colloids intended for lymphoscintigraphic application
    The Journal of Nuclear Medicine, 2001
    Co-Authors: Chris Tsopelas
    Abstract:

    Colloidal particle size is an important characteristic to consider when choosing a radiopharmaceutical for mapping sentinel nodes in lymphoscintigraphy. Methods: Photon correlation spectroscopy (PCS) and transmission electron microscopy (TEM) were used to determine the particle size of Antimony Trisulfide and rhenium sulfide colloids, and membrane filtration (MF) was used to determine the radioactive particle size distribution of the corresponding 99mTc-labeled colloids. Results: Antimony Trisulfide was found to have a diameter of 9.3 ± 3.6 nm by TEM and 18.7 ± 0.2 nm by PCS. Rhenium sulfide colloid was found to exist as an essentially trimodal sample with a dv(max1) of 40.3 nm, a dv(max2) of 438.6 nm, and a dv of 650–2200 nm, where dv is volume diameter. 99mTc-Antimony Trisulfide by MF showed that more than 96% of radioactive particles were smaller than 100 nm; however, 99mTc-rhenium sulfide showed that more than 21% were smaller than 100 nm. These radioactive colloids were used with seven different membrane compositions and found not to adsorb significantly to any of them. Conclusion: MF was validated as a simple and reliable technique to estimate the percentage radioactive particle size distribution.

Keon Wook Kang - One of the best experts on this subject based on the ideXlab platform.

  • comparison of the results for sentinel lymph node mapping in the breast cancer patients using 99m tc Antimony Trisulfide colloid 99m tc tin colloid and 99m tc human serum albumin
    Nuclear Medicine and Molecular Imaging, 2007
    Co-Authors: S J Jang, Seung Hwan Moon, Seoil Kim, Bom Sahn Kim, Seongjang Kim, K W Chung, E S Lee, Keon Wook Kang
    Abstract:

    Purpose: In the breast cancer patient, lymphatic mapping and sentinel lymph node biopsy are the most important procedure for axillary lymph node staging. We aimed to compare the three radiocolloids [-Antimony Trisulfide colloid (ASC), -tin colloid (TC), and -human serum albumin (HSA)] for sentinel lymph node mapping. Subjects and Methods: Totally, 397 patients with clinically N0 stage were enrolled. -ASC was injected in 202 out of 397 patients, -TC was injected in 120 patients, and -HSA was injected in the remaining 75 patients. The sentinel lymph nodes were localized by lymphoscintigraphy and selected using intraoperative gamma probe. All sentinel lymph nodes were investigated by intraoperative pathologic consultation. The axillary lymph nodes which were harvested by the lymph node dissection were also investigated. Results: The patients of each group showed similar clinical characteristics. There were no significant differences (p>0.05) in the identification rate of sentinel lymph nodes (IR), false negative rate (FNR), and negative predictive value (NPV). The axillary lymphadenectomy revealed axillary lymph node metastases in those three groups (ASC-33.2%, TC-31.7%, HSA-22.7%). The IR, FNR, and NPV were not significantly different among those groups. Conclusion: Those three -labeled radiocolloids showed equivalent results in sentinel lymph node mapping of breast cancer.

Hong Yin - One of the best experts on this subject based on the ideXlab platform.