We have previously reported that replacing bone marrow stem cells may improve hyperglycemia and oxidative stress in db/db mice, a type 2 diabetic mouse model. Senescence marker protein 30 (SMP30) is an antioxidant protein that decreases with aging. However, it has not been clear whether SMP30 decreases in the livers of obese mice, and whether stem cell replacement would improve SMP30 expression in the liver. Bone marrow stem cells of db/db mice were replaced with the bone marrow stem cells of C57BL/6 mice. Plasma cytokine and insulin levels were measured, and glycogen content, expression of SMP30, and fibrosis in the liver were assessed. Our results showed that stem cell replacement increased the expression of SMP30 in the liver, resulting from decreased plasma inflammation cytokines and hyperinsulinemia in db/db mice. This is the first report that stem cell replacement increased the expression of SMP30 in the liver, and may help prevent fibrosis in the liver of db/db mice. 相似文献
For more efficient use of membranes, the control of irreversible membrane fouling, which can be defined as fouling requiring chemical reagents to be mitigated, is of importance. In this study, irreversible fouling caused by constituents in surface water was investigated, based on a long-term pilot scale study. The membrane employed was a low-pressure hydrophobic ultrafiltration (UF) membrane made of polysulfone and having a molecular weight cutoff of 750,000 Da. Various chemical reagents were examined to overcome the irreversible fouling that had developed through 5 months of continuous filtration. Among the tested cleaning reagents, alkaline (NaOH) and oxidizing reagent (NaClO) showed good performance in the restoration of membrane permeability, which implied that organic matter played an important role in the development of the irreversible fouling in this study. Chemical analysis, adsorptive fractionation methods, fluorescence excitation-emission matrix (EEM) and Fourie-transformed infra-red (FTIR) spectra analysis were applied to elucidate which fraction of organic matter caused the irreversible fouling. All of the analysis indicated that polysaccharide-like organic matter was responsible for the evolution of the irreversible fouling. In addition to organic matter, presumably iron and manganese also contributed to the irreversible fouling to some extent. 相似文献
The interactions between organic friction modifiers (FMs) and other additives in a continuously variable transmission (CVT) fluid (CVTF) are investigated with the goal of optimizing friction management of metal pushing V-belt CVTs. Three types of FMs (oleic acid, oleyl alcohol, and glycerol mono-oleate [GMO]) were formulated in poly-α-olefin (PAO) and a fully formulated CVTF, and the friction performance was evaluated in a reciprocating test apparatus (TE77). To estimate their effect on the major frictional components in the CVTs, a steel belt–pulley and a torque converter clutch, the tribotests were carried out with both steel–steel and paper–steel sliding configurations. Then, the posttest materials were assessed by surface analysis techniques to observe the chemical nature of any reacted layers at the surface.
The results indicate that the friction on the steel surface was significantly influenced by a combination of the FMs and the CVTF additives as well as the functional group of the FMs. Although oleic acid and GMO typically present greater friction reduction than oleyl alcohol under most conditions, oleic acid did not decrease friction at the steel–steel contact with the presence of the other additives in the CVTF formulation; the friction reduction effect was impaired by the presence of other additives. Surface analysis of the posttest specimens implied that it was interactions with the calcium detergent that inactivated the FM effect of oleic acid. 相似文献
The horizontal orientation of the transition dipole moment of the phosphorescent emitters is understood to be an important factor to enhance the external quantum efficiency (EQE) of organic light-emitting diodes by improving light out-coupling in optical microcavity structures. Here, red-emitting heteroleptic iridium (III) complexes exhibiting an extremely high horizontal ratio of emitting dipole orientation (EDO) and photoluminescence quantum yield (PLQY), as well as longer device operational lifetime, without scarifying any other photophysical properties are reported. The systematic molecular design of main and ancillary ligands in heteroleptic iridium complexes leads to the achievement of both a horizontal EDO of 92% and a PLQY of 98% in the red-emitting phosphorescent devices along with a shorter exciton decay time of 0.71 µs. Accordingly, the red-emitting devices show excellent performances of maximum EQE of 32% and low-efficiency roll-off with the 1931 Commission Internationale de L′Eclariage coordinates of (0.66, 0.34). Therefore, this approach opens the way for further development of new red-emitting iridium complexes pushing the device efficiency toward the theoretical limits. 相似文献
Salinipeptins belong to the type-A linaridin class of ribosomally synthesized and post-translationally modified peptides (RiPPs) comprising 22 amino acid residues with multiple D -amino acids. Although chirality of other type-A linaridins, such as grisemycin and cypemycin, has not been reported, the biosynthetic gene clusters of type-A linaridins have identical gene organization. Here, we report heterologous expression of grisemycin biosynthetic gene cluster (grm) and show that grisemycin contains multiple D -amino acids, similar to salinipeptins. The heterologous expression experiments also confirm the involvement of a novel peptide epimerase in grisemycin biosynthesis. Gene-deletion experiments indicate that grmL, a single gene with unknown function, is indispensable for grisemycin production. We also show that the presence of D -amino acids is likely a common feature of linaridin natural products by analyzing two other type-A linaridin clusters. 相似文献
Information Systems and e-Business Management - Consider a monopolistic vendor who faces a known demand curve. By setting a price that equates marginal revenue with marginal cost, the vendor will... 相似文献