Structural and electronic properties of extremely long perylene bisimide nanofibers formed through a stoichiometrically mismatched, hydrogen-bonded complexation

Extremely long nanofibers, whose lengths reach the millimeter regime, are generated via co-aggregation of a melamine-appended perylene bisimide semiconductor and a substituted cyanurate, both of which are ditopic triple-hydrogen-bonding building blocks; they co-aggregate in an unexpected stoichiometrically mismatched 1:2 ratio. Various microscopic and X-ray diffraction studies suggest that hydrogen-bonded polymeric chains are formed along the long axis of the nanofibers by the 1:2 complexation of the two components, which further stack along the short axis of the nanofibers. The photocarrier generation mechanism in the nanofibers is investigated by time-of-flight (TOF) experiments under electric and magnetic fields, revealing the birth and efficient recombination of singlet geminate electron-hole pairs. Flash-photolysis time-resolved microwave conductivity (FP-TRMC) measurements revealed intrinsic 1D electron mobilities up to 0.6 cm(2) V(-1) s(-1) within nanofibers.     

Rattle‐Type Fe3O4@SiO2 Hollow Mesoporous Spheres as Carriers for Drug Delivery

Rattle‐type Fe₃O₄@SiO₂ hollow mesoporous spheres with different particle sizes, different mesoporous shell thicknesses, and different levels of Fe₃O₄ content are prepared by using carbon spheres as templates. The effects of particle size and concentration of Fe₃O₄@SiO₂ hollow mesoporous spheres on cell uptake and their in vitro cytotoxicity to HeLa cells are evaluated. The spheres exhibit relatively fast cell uptake. Concentrations of up to 150 µg mL^?1 show no cytotoxicity, whereas a concentration of 200 µg mL^?1 shows a small amount of cytotoxicity after 48 h of incubation. Doxorubicin hydrochloride (DOX), an anticancer drug, is loaded into the Fe₃O₄@SiO₂ hollow mesoporous spheres, and the DOX‐loaded spheres exhibit a somewhat higher cytotoxicity than free DOX. These results indicate the potential of Fe₃O₄@SiO₂ hollow mesoporous spheres for drug loading and delivery into cancer cells to induce cell death.     

Boiling heat transfer from a horizontal flat plate in a pool of liquid hydrogen

Heat transfer from a flat plate facing upward immersed in a liquid hydrogen pool was measured for the pressures from atmospheric to 1.1 MPa. The flat plate heater used was 10 mm in width, 100 mm in length and 0.1 mm in thickness. Critical heat fluxes (CHFs) in saturated boiling increased with the increase in pressure up to around 0.3 MPa and then decreased with further pressure increase. The CHFs under subcooled condition at each pressure increased with the increase in sub-cooling. Discussions were made on the experimental results by comparing with those of the other cryogenic liquids and also the Kutateladze’s equations under saturated and subcooled conditions. The experimental CHFs were much smaller than the Kutateladze’s equation for higher pressure up to critical. The heater surface temperature was found to reach the critical temperature before the occurrence of hydrodynamic instability and jump to the film boiling regime at the lower heat flux in the higher pressure range. It was suggested that the CHFs are determined not by the heat flux but by the temperature in the higher pressure range.     

Prenatal Exposure to Polycyclic Aromatic Hydrocarbons and Birth Outcomes

The effect of prenatal exposure to polycyclic aromatic hydrocarbons (PAHs) at the environmental level on birth size was examined. The concentration of 1-hydroxypyrene (1-OHP) in spot urine samples collected from 50 pregnant women in Tokyo was measured and was related to birth weight, length, and head circumference of the newborns the subjects delivered. Analysis of inter- and intra-individual variation in 1-OHP concentration in spot urine samples from non-smoking subjects revealed that single spot urine can represent the subject's exposure to PAHs over several weeks and utility of spot urine for assessing PAHs exposure level of non-smokers was indicated. Geometric mean urinary concentration of 1-OHP of the subjects was 0.056 μmol/mol creatinine, and smoking mothers (n = 7) excreted more 1-OHP (0.200 μmol/mol-cre) than non-smoking mothers (0.046 μmol/mol-cre). Multiple regression analysis using birth outcomes as the dependent variable and urinary 1-OHP and other covariates as independent variables revealed that urinary 1-OHP was not a significant variable to explain birth outcomes among non-smoking mothers.     

Friction and wear of carbon steel near T1-transition under dry sliding

The wear phenomenon of metals under dry sliding is, generally, divided into two modes of severe and mild wear. A discontinuous transition between the wear modes often takes place in a certain load range. The T₁-transition is usually observed at lower levels of load or sliding velocity. There is a great difference in wear rate between severe and mild wear. This indicates that the occurrence of severe wear should be avoided, especially in the field of machine design to prevent energy loss, occurrence of noise and vibration, and life reduction of machines and their components. Therefore, it is important for machine designers to know the relationship between friction and wear and the difference in properties of the wear surfaces in the two wear modes. In this study, wear tests of 0.35% C steel in contact with itself under constant load were conducted in moist air at various contact loads under dry sliding. The friction and wear were measured continuously throughout each test. After the tests, the relationship between friction and wear and the difference in properties of the wear surfaces were investigated in each wear mode. From the results, the upper and lower critical loads (P_acr and P_Acr) appeared between severe and mild wear. The phenomenon of zero wear has been newly found in the early period at very low loads. The zero wear continued for a long sliding distance and then changes to mild wear. The critical load between zero wear and mild wear is defined as P_zerowear. The load was changed once in a step-wise manner from low to high levels in process of test. Since the rubbing history under mild wear condition at the low load in the first stage affected the properties of wear surface, the wear mode at the high load in the second stage changed from ‘mild wear’ to ‘quasi-mild wear’ having a low rate. From the relationship between sliding distance necessary for the appearance of quasi-mild wear and contact load in the first stage, the boundary curve between severe wear and quasi-mild wear in the second stage is hyperbolic. This curve gradually approaches P_zerowear with decreasing contact load. Thus, P_zerowear is one of the important critical loads for elucidating the test results under varying load.     

Comparative analysis of the determinants of fees charged by fee-based homes for the elderly in urban and suburban areas

This study contributes to establishing the payment function of fee-based homes for the elderly. Disclosure statements from such homes for the elderly in selected urban and suburban cities in Fukuoka Prefecture, Japan—considered a typical prefecture with adjoining urban and suburban areas—were examined. The study compared the determinants of the amounts charged by the homes based on the distinct geographic features of urban and suburban areas. The hedonic price model was combined with a two-stage least squares regression to determine the determinants of lump-sum and monthly payments. We found that the factors that influence monthly payments in urban areas include distance to a park, distance to the coast, meals offered, number of care staff, and initial lump-sum payment. In contrast, factors such as room size, distance to a bus stop, distance to a park, and the number of night staff influence monthly payments in suburban areas. We conclude that the surrounding landscape has a greater influence on monthly payments in urban areas than in suburban areas. Moreover, in suburban areas, the number of night staff has a substantial impact on monthly payments. The results can help provide investment suggestions in certain cases depending on the amount of investment capital.

     

Fabrication of ferromagnetic nanoconstriction using atomic force microscopy nanoscratching

Nanolithography used in conjunction with atomic force microscopy (AFM) has attracted considerable attention as a technique for fabricating nanoscale structures. To obtain nanostructures and devices, AFM nanoscratching was performed on a photoresist and on NiFe at various values of the applied force, scan speed, and number of scan cycles. The scratching process was carried out using a diamond-coated tip on NiFe and a Si tip on the photoresist. By conducting scratching processes on NiFe and on the photoresist, we investigated the dependence of the size of the scratched part on the scratching parameters. These results show that the width and depth of the scratched part increase as the applied force and number of scan cycles increase, but not as the scan speed increases. This means that it is possible to control the size of the scratched parts by adjusting the applied force and number of scan cycles. AFM nanoscratching was then used to directly fabricate a nanoconstricted area with a width of 139 nm and a cross-sectional area of less than 300 nm2 was fabricated.     

Fast calculation using parallel processing and pipeline processing in power system analysis

This paper presents an application of parallel processing and pipeline processing to power system analysis. The system matrix is transformed to a bordered block diagonal form (BBDF) matrix for effective utilization of the processors. After LU factorization, subnetworks organize sparse matrices and the boundary network organizes a full matrix. First, a parallel processing technique is used to calculate subnetworks. Then, as pipeline processing is applied, inverse matrix of the boundary network is multiplied. The proposed method is made operational on a parallel computing system including a pipeline processor. A consideration on the transient stability analysis using the proposed method also is presented at the end of this paper.