Comparative analysis of phytochemicals and polar metabolites from colored sweet potato (Ipomoea batatas L.) tubers

Food Science and Biotechnology - We determined the phytochemical diversity, including carotenoids, flavonoids, anthocyanins, and phenolic acids, in sweet potatoes (Ipomoea batatas L.) with...     

Factors and Pathways Modulating Endothelial Cell Senescence in Vascular Aging

Aging causes a progressive decline in the structure and function of organs. With advancing age, an accumulation of senescent endothelial cells (ECs) contributes to the risk of developing vascular dysfunction and cardiovascular diseases, including hypertension, diabetes, atherosclerosis, and neurodegeneration. Senescent ECs undergo phenotypic changes that alter the pattern of expressed proteins, as well as their morphologies and functions, and have been linked to vascular impairments, such as aortic stiffness, enhanced inflammation, and dysregulated vascular tone. Numerous molecules and pathways, including sirtuins, Klotho, RAAS, IGFBP, NRF2, and mTOR, have been implicated in promoting EC senescence. This review summarizes the molecular players and signaling pathways driving EC senescence and identifies targets with possible therapeutic value in age-related vascular diseases.     

Design and evaluation of proton accelerator beam window cooling configuration

A 100 MeV, 20 mA proton linear accelerator is being constructed as a part of the Proton Engineering Frontier Project (PEFP) funded by the Korean Ministry of Education, Science and Technology’s (MEST). To irradiate a target with proton beam for multiple applications, a beam window with a sound structure is essential, which successfully divides the accelerator compartment from the target. This paper presents how the cooling method for beam window was designed while considering various factors. Multiple cooling configurations were considered during the beam window design phase and each cooling configuration was tested to determine if the configuration successfully minimizes average temperature of the window during irradiation and also minimizes hot spot area. The heat transfer analysis was followed by a structure analysis to determine if the beam window can satisfy the design requirements. Through this investigation, the requirements for beam window cooling configuration and fabricated material were identified and these newly found requirements will be iterated to improve the final design.     

Numerical study on effects of building groups on dam-break flow in urban areas

In this study, the effects of flood waves on urban areas due to a dam failure are numerically investigated based on two physical experiments and a field study case. The numerical model is a two-dimensional unstructured finite volume model based on the shallow-water equations and well-balanced HLLC scheme. The predicted water depths are consistent with available laboratory measurements. In laboratory experiments, a relatively high water depth and the delay effects of flow at the front of urban areas are observed. The urban areas may become a large obstacle to the propagation of the flood wave. In the case study of the Tous Dam failure in Spain, the calculated water depths agree very well with those from existing numerical model, but some discrepancies still exist. Considering the uncertainty of field survey data, the water depths obtained from this study are quite reasonable.     

Analysis of ring pack lubrication

This paper describes a method developed for the simulation of ring pack lubrication characteristic in an internal combustion engine. In general, the quantity of oil supply for piston ring lubrication may be insufficient in filling the entire volume formed at the interference between the piston ring and the cylinder liner. Thus the oil starvation condition should be considered in analyzing piston ring lubrication. In order to reasonably estimate the amount of oil left over on the cylinder liner, the flow rate at the posterior portion of the interface should be calculated with an adequate boundary condition that confirms flow continuity condition. In this analysis, oil starvation and open-end boundary conditions are considered at the inlet and outlet of the piston rings. The lubrication characteristic of each piston ring is obtained by an iterative method with sequential steps. It is revealed that piston rings are operated under oil starvation in most operating cycles and the result under these conditions are quite different from that with the fully-flooded assumption.     

Analysis of the piston ring lubrication with a new boundary condition

Research on the inlet and outlet lubricational characteristics of the piston ring have been intense and ongoing. Many researchers had considered that the entire surface of the ring was enveloped in an oil film, but much experimental research has discovered that not all the entire surface was soaked. To consider a partially lubricated ring, the following conditions are presupposed; oil starvation is applied to the inlet region and the open-end assumption to the outlet region. This algorithm confirms flow continuity and permits the nadir of the pressure to go down to the saturation pressure. Using these new boundary conditions, the actual effective width participating in ring lubrication is determined and the minimum film thickness and flow rate for the ring pack can be calculated. The effective width is expected to be about 20 to 30 percent of the whole width of the ring, and the minimum film thickness is less than the result obtained by using the Reynolds cavitation boundary condition.     

Identification of two amino acids contributing the high enzyme activity in the alkaline pH range of an alkaline endoglucanase from a Bacillus sP

An alkaline cellulase ß-1,4-endoglucanase; NK1) froman alkalophilk Bacillus sp. shows great similarity in aminoacid sequence to a neutral cellulase (BSC) from Bacillus subtilis,despite a considerable difference in their pH activity profiles.Multiple amino acid exchanges by site-directed mutagenesis,using BSC as the reference, were performed on the residues inregion 5 of NK1, which was previously shown to be responsiblefor the high enzyme activity of this alkaline cellulase in abroad alkaline pH range. Two amino acid residues, Ser287 andAla296, were identified as being responsible for the activityin the alkaline range. The double mutation, Ser287 to Asn andAla296 to Ser, of NK1 made its pH activity profile almost thesame as that of BSC. On the other hand, the pH activity profilein the acidic range was not significantly affected by variousamino acid replacements including these two positions in region5. This observation, together with the information availableon other endoglucanases, suggests that the above two amino acidsubstitutions caused a profound effect through rearrangementof the hydrogen bond network forming the substrate-binding siteor the catalytic site.     

Enhanced oral absorption of salmon calcitonin-encapsulated PLGA nanoparticles by adding organic substances

Two organic compounds with potential absorption enhancing effects, bile acids and transferrin, were examined by the gastro-intestinal (GI) absorption of therapeutic salmon calcitonin (sCT) as encapsulated by poly(lactide-co-glycolide) (PLGA) for the treatment of osteoporosis. The sCT-loaded PLGA nanocapsules were prepared by O/W emulsification approach. Either additive of a designated content was mixed with sCT dissolved in methanol. For bile acids, their content (0–7.5 mg to sCT 6 mg) was observed to have a substantial effect both on the emulsification process and the encapsulation efficiency. When 1.5 mg of bile acids was added, sCT-loaded PLGA nanocapsules of about 700 nm in diameter and with a fairly high encapsulation efficiency greater than 35% were produced. Accordingly, this formulation gave the most significant hypocalcemic effect in an in vivo experiment with SD rats. On the other hand, a too high bile acids loading resulted in a poor encapsulation efficiency of less than 7%. Two principal roles of bile acids were proposed: emulsifying agent and absorption enhancer. Transferrin, a human glycoprotein of 80 kDa molecular weight, turned out to have potential as absorption enhancer as well.