Leakage analysis of helical grooved pump seal using CFD

Journal of Mechanical Science and Technology - The helical grooved seal, which is a non-contact sealing device using the viscosity of the fluid, prevents leakage by reducing fluid pressure...     

Designing Animated Transitions to Convey Aggregate Operations

Data can be aggregated in many ways before being visualized in charts, profoundly affecting what a chart conveys. Despite this importance, the type of aggregation is often communicated only via axis titles. In this paper, we investigate the use of animation to disambiguate different types of aggregation and communicate the meaning of aggregate operations. We present design rationales for animated transitions depicting aggregate operations and present the results of an experiment assessing the impact of these different transitions on identification tasks. We find that judiciously staged animated transitions can improve subjects' accuracy at identifying the aggregation performed, though sometimes with longer response times than with static transitions. Through an analysis of participants' rankings and qualitative responses, we find a consistent preference for animation over static transitions and highlight visual features subjects report relying on to make their judgments. We conclude by extending our animation designs to more complex charts of aggregated data such as box plots and bootstrapped confidence intervals.     

Characterisation and partial purification of an antimutagenic peptide produced by Lactobacillus plantarum JNU 2116

The antimutagenic activities of sixteen strains of Lactobacillus were evaluated using three mutagens (4‐nitroquinoline‐N'‐oxide, 4‐NQO; N‐methyl‐N'nitro‐N‐nitrosoguanidine, MNNG; and 2‐amino‐3‐methylimidazole quinoline, IQ). Among the tested Lactobacillus strains, Lactobacillus plantarum strain JNU 2116 had the highest antimutagenic activity in the presence of 4‐NQO, MNNG and IQ (21.5, 25.8 and 34.54% inhibition, respectively). The molecular weight of the antimutagenic peptide was estimated at approximately 762 Da, and the N‐terminal amino acid residue sequence of the purified peptide was identified as NH₂‐ XLEXKKAEXITTXX. This peptide may be able to counteract the activity of carcinogens and other toxins if it is added to functional dairy products.     

The involvement of ATPase activity in the acid tolerance of Lactobacillus rhamnosus strain GG

This study examined the survival and acid stress response of nine lactic acid bacteria (LAB) including Lactobacillus rhamnosus strain GG in commercially available yoghurt products (low pH environment) during the long‐term storage. Under the storage conditions investigated (52 weeks period at 5 °C), there was a loss of the viability of Lactobacillus acidophilus, Lactobacillus casei and Bifidobacterium sp. within 35 weeks. However, L. rhamnosus strain GG, one of starter strains in a commercially available yoghurt product, exhibited excellent survival throughout the whole storage period. Our results indicate that the viability of L. rhamnosus strain GG was increased by modulating the stress‐related factors as well as the activity of ATPase with exposure to the low pH conditions.     

Layer‐by‐Layer Controlled Perovskite Nanocomposite Thin Films for Piezoelectric Nanogenerators

Perovskite nanoparticle‐based nanocomposite thin films strictly tailored using unconventional layer‐by‐layer (LbL) assembly in organic media for piezoelectric nanogenerators (NGs) are demonstrated. By employing sub‐20‐nm BaTiO₃ nanoparticles stabilized by oleic acid ligands (i.e., OA‐BTO_NPs) and carboxylic acid (COOH)‐functionalized polymers, such as poly(acrylic acid) (PAA), the resulting OA‐BTO_NP/PAA nanocomposite multilayers are prepared by exploiting the high affinity between the COOH groups of PAA and the BTO_NPs. The ferroelectric and piezoelectric performance of the (PAA/OA‐BTO_NP)_n thin films can be precisely controlled by altering the bilayer number, inserted polymer type, and OA‐BTO_NP size. It is found that the LbL assembly in nonpolar solvent media can effectively increase the quantity of adsorbed OA‐BTO_NPs, resulting in the dramatic enhancement of electric power output from the piezoelectric NGs. Furthermore, very low leakage currents are detected from the (PAA/OA‐BTO_NP)_n thin films for obtaining highly reliable power‐generating performance of piezoelectric NGs.     

A three-dimensional passage flow analysis method aimed at centrifugal impellers

A partially parabolic procedure is developed to analyze three-dimensional viscous flows through curved ducts of arbitrary cross-section. The procedure, eventually aimed at centrifugal impeller analysis, incorporates a finite-volume method using a strong conservation form of the parabolized Navier-Stokes equations written in arbitrary curvilinear coordinates. Cartesian velocity components and pressure are used as dependent variables. A solution is achieved through pressure corrections which influence velocity semi-implicity. The basic physical elements associated with centrifugal impellers are considered. Laminar flow through 90° bent square duct, turbulent flow in low-aspect-ratio diffusers and subsonic compressible flow through an accelerating rectangular elbow are calculated. Turbulence is accounted for using the k − ε turbulence model. Good correlation between the predictions and experimental data was achieved.     

Polymeric worm micelles as nano-carriers for drug delivery

Nanoscale carriers of active compounds, especially drugs, need not be spherical in shape. Worm micelles as blends of degradable polylactic acid (PLA) and inert block copolymer amphiphiles were prepared for controlled release and initial study of carrier transport through nano-porous media. The loading capacity of a typical hydrophobic drug, Triamterene, and the release of hydrophobic dyes were evaluated together with morphological changes of the micelles. Degradation of PLA by hydrolysis led to the self-shortening of worms and a clear transition towards spherical micelles, correlating with the release of hydrophobic dyes. Perhaps equally important for application is the flexibility of worm micelles, which we show allows them to penetrate nanoporous gels where 100?nm sized vesicles cannot enter. Such gels have served as tissue models, and so the results here collectively suggest a new class of hydrophobic drug nano-carriers that are capable of tissue permeation as well as controlled release.