Characteristics of pebble shape and the amount of pebble abrasion measured with a replica reproduced on a curling rink.

The shape of pebbles on a curling rink was measured using a replica of the ice surface of the rink to understand the characteristics of pebbles after being in contact with stones. We focused on pebbles with flat tops for which the average shape was 3.81 mm in diameter at the lower base, 1.16 mm in diameter at the upper surface, 0.12 mm in maximum height, and 5.4° in contact angle. A scratch of about 1 µm in depth and 40 µm in width (traces of pebbles cut by a running band at the bottom of the stone) was observed on the upper surface. The pebbles were also found to have a moderate lower base diameter that preferentially contacted the nipper or stone due to its large maximum height value immediately after formation. Experiments to determine the amount of pebble abrasion associated with the passing of stones revealed that the average height of their upper surface decreased by 1 µm and the area of the upper surface increased by 0.21 mm2 for each stone passing as the stone cut the pebbles.

The importance of the surface roughness and running band area on the bottom of a stone for the curling phenomenon.

Curling is a sport in which players deliver a cylindrical granite stone on an ice sheet in a curling hall toward a circular target located 28.35 m away. The stone gradually moves laterally, or curls, as it slides on ice. Although several papers have been published to propose a mechanism of the curling phenomenon for the last 100 years, no established theory exists on the subject, because detailed measurements on a pebbled ice surface and a curling stone sliding on ice and detailed theoretical model calculations have yet to be available. Here we show using our precise experimental data that the curl distance is primarily determined by the surface roughness and the surface area of the running band on the bottom of a stone and that the ice surface condition has smaller effects on the curl distance. We also propose a possible mechanism affecting the curling phenomena of a curing stone based on our results. We expect that our findings will form the basis of future curling theories and model calculations regarding the curling phenomenon of curling stones. Using the relation between the curl distance and the surface roughness of the running band in this study, the curl distance of a stone sliding on ice in every curling hall can be adjusted to an appropriate value by changing the surface roughness of the running band on the bottom of a stone.

Human induced hepatic lineage-oriented stem cells: autonomous specification of human iPS cells toward hepatocyte-like cells without any exogenous differentiation factors.

Preparing targeted cells for medical applications from human induced pluripotent stem cells (hiPSCs) using growth factors, compounds, or gene transfer has been challenging. Here, we report that human induced hepatic lineage-oriented stem cells (hiHSCs) were generated and expanded as a new type of hiPSC under non-typical coculture with feeder cells in a chemically defined hiPSC medium at a very high density. Self-renewing hiHSCs expressed markers of both human embryonic stem cells (hESCs) and hepatocytes. Those cells were highly expandable, markedly enhancing gene expression of serum hepatic proteins and cytochrome P450 enzymes with the omission of FGF-2 from an undefined hiPSC medium. The hepatic specification of hiHSCs was not attributable to the genetic and epigenetic backgrounds of the starting cells, as they were established from distinct donors and different types of cells. Approximately 90% of hiHSCs autonomously differentiated to hepatocyte-like cells, even in a defined minimum medium without any of the exogenous growth factors necessary for hepatic specification. After 12 days of this culture, the differentiated cells significantly enhanced gene expression of serum hepatic proteins (ALB, SERPINA1, TTR, TF, FABP1, FGG, AGT, RBP4, and AHSG), conjugating enzymes (UGT2B4, UGT2B7, UGT2B10, GSTA2, and GSTA5), transporters (SULT2A1, SLC13A5, and SLCO2B1), and urea cycle-related enzymes (ARG1 and CPS1). In addition, the hepatocyte-like cells performed key functions of urea synthesis, albumin secretion, glycogen storage, indocyanine green uptake, and low-density lipoprotein uptake. The autonomous hepatic specification of hiHSCs was due to their culture conditions (coculture with feeder cells in a defined hiPSC medium at a very high density) in self-renewal rather than in differentiation. These results suggest the feasibility of preparing large quantities of hepatocytes as a convenient and inexpensive hiPSC differentiation. Our study also suggests the necessity of optimizing culture conditions to generate other specific lineage-oriented hiPSCs, allowing for a very simple differentiation.

Assembly of zinc finger motif-fused enzymes on a dsDNA scaffold for catalyzing consecutive reactions with a proximity effect.

The feasibility of assembling enzymes, catalyzing consecutive reactions, on to a double-stranded DNA (dsDNA) scaffold utilizing zinc finger motifs is described. The catalytic activities of two zinc finger motif-fused enzymes catalyzing a bioluminescence reaction with energy recycling, namely pyruvate phosphate dikinase and firefly luciferase, have been evaluated. Bioluminescence measurements with dsDNA scaffolds coding a different distance between the binding sites for each zinc finger motif-fused enzyme confirmed the effect of the distance, proving the proximity effect of ATP recycling presumed to be the result of efficient intermediate diffusion. Thus, fusion to zinc finger motifs offers a promising option for the assembly of bi-enzymes, catalyzing a consecutive reaction, onto a dsDNA scaffold with a proximity effect.