The discovery of fullerine-related carbon nanotube structures in 1991 [1] has renewed hopes of approaching the theoretical limit of tensile strength. Such structures grow as concentric cylinders and are nearly defect-free. Indirect measurements of the mechanical properties of these nanotubes have yielded very high moduli (Table 1). Direct tensile testing of individual tubes, however, has proved challenging, however, due to their extremely small size. We have developed a tensile testing stage for this purpose, using microfabrication techniques. This device enables the direct application of a tensile strain to individual nanotubes while they are viewed in a transmission electron microscope.Carbon nanotubes were synthesized by arc discharge using a B-doped carbon anode[2]. The tensile testing device was fabricated from silicon utilizing microfabrication techniques. Tension was applied utilizing a piezoelectric manipulation holder, fabricated in-house, the details of which have been provided earlier [3][4][5]. Figures 1a and 1bshow the nanotube under test before and after tensile testing. Examination of individual video frames reveals a strain of just over 5%, prior to failure. It should also be noted that no narrowing down of the nanotube was observed immediately before fracture, which is consistent with the lower temperature deformation mechanism predicted from dislocation theory [6]. Figure 1b also reveals that the tube has apparently "healed" itself by forming a closed endcap. Based on our observed tensile force at failure (18 microNewtons) and the measured cross sectional area of the nanotube (123 nm 2 , based on a tube diameter of 12.5 nm), our computed tensile stress to breakage is 0.15 TPa. This value generally is in general agreement with exceeds that predicted by the Orowan-Polyanyi relation, utilizing E=1.026 TPa [7] for the graphene sheet. Although we were unable to obtain direct resolution of individual walls in the nanotube under test, both the "core" and "wall" regions are clearly visible. Based on measurements taken from these images, we calculate the number of walls as ~ 13. Our higher value of tensile stress to failure, coupled with the observation of the fracture surfaces suggests that the outermost walls break nearly at once. Examination of still micrographs before and after the event reveals much higher elongation, suggesting that the inner tubes may undergo a "sword in sheath" [8], (telescoping) phenomenon prior to failure.The large elastic modulus and breaking strength determined for these multiwalled carbon nanotubes in addition to the elastic buckling observed during testing should render carbon nanotube reinforced composites particularly applicable where energy-absorbing properties are desired.

Human metabolism of D-fructose, D-sorbitol, D-mannitol, and xylitol has been documented. In humans, sorbitol and xylitol at a single oral dose of 20 g or less and fructose at 70 g or less most likely can be fully absorbed. These there sugars can maintain, either independently or nearly independently, the integrity or the carbohydrate requirement for the growth of cells and animals. The absorption of D-mannitol is no more than 80% and is more laxative. In general, there is no adverse effect other than osmotic diarrhea after oral administration of these sugars. Transient hyperuricemia was seen in some humans. The chronic toxicity of life-long usage of these sugars in humans or other primates is not known. However, a 2-year Turku sugar studies suggested the safety of fructose and xylitol. Two-year feeding experiments in mice and rats indicated possible carcinogenicity of a high-percentage xylitol diet. Abnormalities of cellular growth were also documented in animals fed high percentages of sorbitol and sucrose. Long-term mannitol feeding experiments also revealed an increased incidence of benign thymic tumors in rats. Intravenous feeding of fructose, xylitol, and sorbitol causes major concern. The toxicity is total-dose and infusion-rate dependent. The physical toxicity induced by hyperosmolar effect of the concentrated infusion solutions can be lethal. The primary metabolic toxicities, mainly lactic acidosis and hypruricemia, are reversible. The suggested safe infusion rate of these sugars is 0.25 g/kg/h; sporadic toxic observations have been reported at this or lower doses (0.125 g/kg/h). The combination of glucose, fructose, xylitol, and sorbitol mixture intravenously is in use in Europe due to the critical threshold of each element. There are positive findings from the use of the combination in human illness (114). The beneficial effect of xylitol, mannitol, sorbitol, and fructose in decreasing order has been well documented in the prevention of dental caries in animals and in humans. Oral organisms do not appear to metabolically adapt to xylitol even after 4 years of in vivo exposure. This was based on the quantitation of xylitol dehydrogenase activity in saliva and oral organisms. In addition, a therapeutic and preventive effect for xylitol in human and animal dental caries has been demonstrated. There appears to be at least a theoretical edge in the dietary use of fructose, xylitol, and sorbitol in diabetics.(ABSTRACT TRUNCATED AT 400 WORDS)

Summary B7-H1 [programmed death-ligand-1 (PD-L1

Mutations in the mitochondrial (mt) genome that result in mt dysfunction, have long been proposed to play important roles in the pathogenesis of hepatocellular carcinoma (HCC). Among these, the common mtDNA 4977 bp deletion is one of the most frequent mutations observed in various cancers. To understand the relationship between the mtDNA 4977 bp deletion and HCC, we performed mutational screening for the presence of this deletion in 105 HCC patients and 69 unrelated healthy subjects. After nested-polymerase chain reaction (nested-PCR) amplification, we found that there were 10 patients carrying the mtDNA 4977 bp deletion, and this deletion was absent in control subjects. Moreover, HCC patients carrying this deletion showed a marked increase in reactive oxygen species (ROS) level and mtDNA copy number when compared with the healthy controls. Taken together, our data indicated that the mtDNA 4977 bp deletion may play important role in the carcinogenesis of HCC, possibly via the alternation of mtDNA copy number and oxidative stress.