Use of Polymeric Compatibilizers in Polypropylene/Calcium Carbonate Composites

Tucker, J . David,Lear, Patricia L .,Atkinson, Gregory S .,Lee, Sung Gyu,Lee, Seung Jong 한국화학공학회 2000 Korean Journal of Chemical Engineering Vol.17 No.5

The effects of compatibilizing agents on the mechanical properties, viscoelastic properties, and morphology of polypropylene filled with calcium carbonate composites are investigated. It is found that the use of PP-g-MA and PP-g-AA significantly increases the tensile strength and improves particle dispersion and interfacial adhesion. The higher effect of compatibilization is obtained by using PP-g-MA as a compatibilizer. The results on the dynamic thermomechanical properties, viscoelastic properties, and SEM pictures also support the improved interfacial characteristics. It is also found that there exists a limiting amount of PP-g-MA at about 5% beyond which a further increase in the tensile strength is not obtained. The use of untreated calcium carbonate or SEBS-g-MA does not allow films to be drawn for the purpose of testing.

Deuterium-incorporated Gate Oxide of MOS Devices Fabricated by Using Deuterium Ion Implantation

이재성,Kevin L. Lear 한국물리학회 2012 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.60 No.7

In the aspect of metal-oxide-semiconductor (MOS) device reliability, deuterium-incorporated gate oxide could be utilized to suppress the wear-out that is combined with oxide trap generation. An alternative deuterium process for the passivation of oxide traps or defects in the gate oxide of MOS devices has been suggested in this study. The deuterium ion is delivered to the location where the gate oxide resides by using an implantation process and subsequent N2 annealing process at the back-end of metallization process. A conventional MOS field-effect transistor (MOSFET) with a 3-nm-thick gate oxide and poly-to-ploy capacitor sandwiched with 20-nm-thick SiO2 were fabricated in order to demonstrate the deuterium effect in our process. An optimum condition of ion implantation was necessary to account for the topography of the overlaying layers in the device structure and to minimize the physical damage due to the energy of the implanted ion. Device parameter variations, the gate leakage current, and the dielectric breakdown phenomenon were investigated in the deuterium-ion-implanted devices. We found the isotope effect between hydrogen- and deuterium-implanted devices and an improved electrical reliability in the deuterated gate oxide. This implies that deuterium bonds are generated effectively at the Si/SiO2 interface and in the SiO2 bulk.

Physical characteristics of frost formation in semi-closed cycle turbine engines

홍성주,William E. Lear,김민수 대한기계학회 2014 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.28 No.4

The power, water extraction, and refrigeration (PoWER) system generates electric power, potable water and refrigeration effects simultaneously,and is composed of a micro-turbine and vapor absorption refrigeration system, which typically uses ammonia, heat exchangers,and a turbocharger. In order to improve the efficiency and the electric output power of the micro-turbine portion of the PoWERsystem, attempts have previously been made to reduce the inlet temperature of the compressor. However, it was problematic to drive itbelow the freezing point since frost or ice forms from the humidity in re-circulated air. As a result, the ice accretion that attaches on thebell mouth or guide vane might increase the pressure drop, leading to performance loss. Furthermore, large sections that break from theice accretion may cause damage to the compressor blades. In this paper experiments have been conducted under the same environmentalconditions as the PoWER system in order to observe the physical characteristic of the frost formation on cylindrical tubes. The resultsshow the thickness of the frost formation for different air velocities (3, 5, 7 m/s) and surface temperatures (-9.8, -16.6, -24.4°C) withrespect to time.

Hypothalamic-Pituitary Axis Regulates Hydrogen Sulfide Production

Hine, Christopher,Kim, Hyo-Jeong,Zhu, Yan,Harputlugil, Eylul,Longchamp, Alban,Matos, Marina Souza,Ramadoss, Preeti,Bauerle, Kevin,Brace, Lear,Asara, John M.,Ozaki, C. Keith,Cheng, Sheue-yann,Singha, S Cell Press 2017 Cell metabolism Vol.25 No.6

<▼1><P><B>Summary</B></P><P>Decreased growth hormone (GH) and thyroid hormone (TH) signaling are associated with longevity and metabolic fitness. The mechanisms underlying these benefits are poorly understood, but may overlap with those of dietary restriction (DR), which imparts similar benefits. Recently we discovered that hydrogen sulfide (H<SUB>2</SUB>S) is increased upon DR and plays an essential role in mediating DR benefits across evolutionary boundaries. Here we found increased hepatic H<SUB>2</SUB>S production in long-lived mouse strains of reduced GH and/or TH action, and in a cell-autonomous manner upon serum withdrawal in vitro. Negative regulation of hepatic H<SUB>2</SUB>S production by GH and TH was additive and occurred via distinct mechanisms, namely direct transcriptional repression of the H<SUB>2</SUB>S-producing enzyme cystathionine γ-lyase (CGL) by TH, and substrate-level control of H<SUB>2</SUB>S production by GH. Mice lacking CGL failed to downregulate systemic T<SUB>4</SUB> metabolism and circulating IGF-1, revealing an essential role for H<SUB>2</SUB>S in the regulation of key longevity-associated hormones.</P></▼1><▼2><P><B>Highlights</B></P><P>•<P>Hepatic H<SUB>2</SUB>S production capacity is elevated in long-lived hypopituitary mouse models</P>•<P>Growth hormone (GH) represses hepatic H<SUB>2</SUB>S production post-transcriptionally</P>•<P>Thyroid hormone (TH) acts via TRβ to repress cystathionine γ-lyase and H<SUB>2</SUB>S levels</P>•<P>H<SUB>2</SUB>S negatively regulates circulating TH and IGF-1 levels</P></P></▼2><▼3><P>Reduced thyroid hormone (TH) and growth hormone (GH) activity are hallmarks of genetic models of longevity in mice. Here, Hine et al. find that TH and GH negatively regulate hepatic production of the longevity-associated gas hydrogen sulfide, which feeds back to negatively regulate circulating TH and IGF-1 levels.</P></▼3>

Amino Acid Restriction Triggers Angiogenesis via GCN2/ATF4 Regulation of VEGF and H₂S Production

Longchamp, Alban,Mirabella, Teodelinda,Arduini, Alessandro,MacArthur, Michael R.,Das, Abhirup,Treviñ,o-Villarreal, J. Humberto,Hine, Christopher,Ben-Sahra, Issam,Knudsen, Nelson H.,Brace, Lear E Elsevier 2018 Cell Vol.173 No.1

<P><B>Summary</B></P> <P>Angiogenesis, the formation of new blood vessels by endothelial cells (ECs), is an adaptive response to oxygen/nutrient deprivation orchestrated by vascular endothelial growth factor (VEGF) upon ischemia or exercise. Hypoxia is the best-understood trigger of VEGF expression via the transcription factor HIF1α. Nutrient deprivation is inseparable from hypoxia during ischemia, yet its role in angiogenesis is poorly characterized. Here, we identified sulfur amino acid restriction as a proangiogenic trigger, promoting increased VEGF expression, migration and sprouting in ECs <I>in vitro</I>, and increased capillary density in mouse skeletal muscle <I>in vivo</I> via the GCN2/ATF4 amino acid starvation response pathway independent of hypoxia or HIF1α. We also identified a requirement for cystathionine-γ-lyase in VEGF-dependent angiogenesis via increased hydrogen sulfide (H<SUB>2</SUB>S) production. H<SUB>2</SUB>S mediated its proangiogenic effects in part by inhibiting mitochondrial electron transport and oxidative phosphorylation, resulting in increased glucose uptake and glycolytic ATP production.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Sulfur amino acid (SAA) restriction triggers angiogenesis independent of hypoxia or HIF1α </LI> <LI> GCN2/ATF4 pathway regulates VEGF and CGL expression upon SAA restriction in ECs </LI> <LI> CGL is required for skeletal muscle angiogenesis activated by diet or exercise </LI> <LI> H<SUB>2</SUB>S triggers glucose uptake, glycolysis, and PPP concomitant with OXPHOS inhibition in ECs </LI> </UL> </P> <P><B>Graphical Abstract</B></P> <P>[DISPLAY OMISSION]</P>

이상지혈증 환자군의 심혈관 질환 위험 등급의 분류에서 LDL콜레스테롤 측정치 혹은 계산치보다 Non-HDL 콜레스테롤이 더 정확하다

Hendrick E. van Deventer,W. Greg Miller,Gary L. Myers,Ikunosuke Sakurabayashi,Lorin M. Bachmann,Samuel P. Caudill,Andrzej Dziekonski,Selvin Edwards,Mary M. Kimberly,William J. Korzun,Elizabeth T. Lear 대한진단검사의학회 2011 Laboratory Medicine Online Vol.1 No.3

Background: Our objective was to evaluate the accuracy of cardiovascular disease (CVD) risk score classification by direct LDL cholesterol (dLDL-C), calculated LDL cholesterol (cLDL-C), and non–HDL cholesterol (non–HDL-C) compared to classification by reference measurement procedures (RMPs) performed at the CDC. Methods: Weexamined 175 individuals, including 138 with CVD or conditions that may affect LDL-C measurement. dLDL-C measurements were performed using Denka, Kyowa, Sekisui, Serotec, Sysmex, UMA, and Wako reagents. cLDL-C was calculated by the Friedewald equation, using each manufacturer’s direct HDL-C assay measurements, and total cholesterol and triglyceride measurements by Roche and Siemens (Advia) assays,respectively. Results: For participants with triglycerides <2.26 mmol/L (<200 mg/dL), the overall misclassification rate for the CVD risk score ranged from 5% to 17% for cLDL-C methods and 8% to 26% for dLDL-C methods when compared to the RMP. Only Wako dLDL-C had fewer misclassifications than its corresponding cLDL-C method (8% vs 17%; P <0.05). Non–HDL-C assays misclassified fewer patients than dLDL-C for 4 of 8 methods (P <0.05). For participants with triglycerides ≥2.26 mmol/L (≥200 mg/dL) and <4.52 mmol/L (<400 mg/dL), dLDL-C methods, in general, performed better than cLDL-C methods, and non–HDL-C methods showed better correspondence to the RMP for CVD risk score than either dLDL-C or cLDL-C methods. Conclusions: Except for hypertriglyceridemic individuals, 7 of 8 dLDL-C methods failed to show improved CVD risk score classification over the corresponding cLDL-C methods. Non–HDL-C showed overall the best concordance with the RMP for CVD risk score classification of both normal and hypertriglyceridemic individuals.