Formation and atomic structure of B12N12 nanocage clusters studied by mass spectrometry and cluster calculation

Boron nitride (BN) nanocage clusters of B₁₂N₁₂ were synthesized, and detected by laser desorption time-of-flight mass spectrometry. The B₁₂N₁₂ clusters consisted of 4- and 6-membered BN rings satisfying the isolated tetragonal rule, which was optimized by molecular orbital calculations. The electronic structure showed a bandgap energy of 5.1 eV, which is a little smaller than that of B₃₆N₃₆ cluster.     

Comparison of Lactic Acid Productivities at High Substrate Conversions in a Continuous Two-stage Fermenter With Cell Recycle Using Different Kinetic Models

The steady-state performance of a two-stage recycle fermenter with two different types (I and II) of configurations for staging was investigated numerically for the continuous production of lactic acid. In Type I the bleed broth withdrawn from the first stage is supplied to the second fermenter, and in Type II both filtrate and bleed broth from the first stage are introduced to the second stage. Using four different kinetic models taken from the literature, the effects of operating parameters on the overall lactic acid productivities and the overall substrate conversions are examined. At moderate conversions, productivities for Type I operation are found to be higher than those for Type II and for the single-stage system. In the case of high conversions close to complete consumption, Type II operation is more efficient than the Type I and single-stage systems. For 99% conversion and 40 kg m^?3 substrate feed concentration, productivities for Type II are predicted to be 14–74% higher compared to those for the single-stage system at the same bleed ratios.     

Topology optimization for thermal conductors considering design-dependent effects,including heat conduction and convection

In structural designs considering thermal loading, in addition to heat conduction within the structure, the heat convection upon the structure’s surface can significantly influence optimal design configurations. In this paper, we focus on the influence of design-dependent effects upon heat convection and internal heat generation for optimal designs developed using a topology optimization scheme. The method for extracting the structural boundaries for heat convection loads is constructed using a Hat function, and heat convection shape dependencies are taken into account in the heat transfer coefficient using a surrogate model. Several numerical examples are presented to confirm the usefulness of the proposed method.     

Age-related changes of element contents in the human meniscus

The relative contents (RCs) of elements in the human menisci from 23 subjects in the age range between 65 and 93 yr were analyzed by inductively coupled plasma atomic emission spectrometry. The RCs of sulfur, calcium, and phosphorus in menisci increased progressively until the 80s, being the highest in the 80s, and thereafter decreased. The RCs of magnesium in menisci increased progressively until the 90s. Regarding the medial and lateral menisci, higher RCs of magnesium and iron, and a lower RC of phosphorus were found in lateral menisci in comparison with those in medial menisci. There were sexual differences in the RCs of calcium and phosphorus of medial and lateral menisci. The RCs of calcium and phosphorus were about 50% higher in women's menisci than in men's. Histological examinations showed that structureless mucoid masses were observed in the menisci, with very high RCs of calcium and phosphorus being detected.     

Effective mechanisms of ATX-S10, a new photosensitizer, on HeLa tumors in nude mice

Photodynamic therapy (PDT) is a treatment modality that utilizes a photosensitizing drug activated by laser generated light. PDT is effective for oncologic applications. Many cancer patients have undergone a hematoporphyrin derivative (HpD)-mediated PDT. The HpD showed a side effect causing prolonged cutaneous photosensitivity. But ATX-S10, a new photosensitizer, provides rapid plasma and tissue clearance, comparable photoactivation efficiency, and superior light absorption of visible red. In this study, the tumor rejection mechanisms of PDT using ATX-S10 on HeLa tumors in nude mice were investigated with morphological and fluorometric methods. The mice were intracutaneously inoculated with HeLa cells, 5 x 10(5) or 1 x 10(7) cells. When tumors grew to about 10-12 mm in diameter, mice were intraperitoneally administered ATX-S10, 30 mg/kg, and 2 hours later the ATX-S10 in tumors was indirectly measured by a fluorometric machine, PMA-10 (Hamamatsu Photonics K. K.) and the tumors were irradiated by Optical Parametric Oscillator (Hamamatsu Photonics K. K.) tuned to a wave length at 670 nm, 5 mJ/pulse, 100 J/tumor. Before and after the irradiation, the effective mechanisms of PDT with ATX-S10 were studied by histological and ultrastructural approaches. The results showed occlusive thrombi in the microvasculature of the tumors and tumor cell death. These occlusive thrombi were observed within one hour after PDT at both light and electron microscopy levels, and were more remarkable as time passed after PDT. Therefore, the morphological studies of PDT with ATX-S10 suggested that the rejection mechanisms occurred mainly as a result of the destructive changes of the microvasculature in the tumors first, and secondly or simultaneously, tumor cells were destroyed through necrosis, and finally the tumors were rejected.     

A new numerical modeling for laminated composites

Recently, with increasing interest in the performance of fiber reinforced laminated composites, various behaviors of these materials have been simulated by the finite element method (FEM). However, conventional models are not good enough to simulate behaviors of laminated composites. The main reason is that the laminated composite is modeled by assuming it to be a homogeneous object though it has a heterogeneous nature. In this paper, the new numerical modeling for laminated composites was proposed. In order to check the validity of the proposed model, elementary simulations were performed and compared with theoretical results. Moreover the application of the proposed model to the laminated composites with interlaminar delamination was discussed.     

Bolted joints of pultruded sandwich composite laminates

This paper describes the tensile behavior of bolted joints of pultruded sandwich composite laminates. The pultruded sandwich laminates have a skin-core-skin structure. Joint strength of longitudinal specimens was independent of specimen width (w), whereas it increased with w in the case of transverse specimens. The joining efficiency of pultruded sandwich laminates was greater in the longitudinal direction than in the transverse direction. The core layer of longitudinal specimens failed by a combination of bearing and shear-out modes, independent of w. The failure mode of skin layers changed from net-tension to bearing mode with increasing w. In transverse specimens, the failure mode of core and skin layers changed from net-tension to bearing with increasing w. Finite element numerical analysis was carried out to predict the failure mode and joint strength. The numerical results were in good correlation with the experimental results.     

A quasi-three-dimensional lateral compressive analysis method for a composite cylinder

This paper presents a lateral compressive analytical method for CFRP cylinders using the quasi-three-elements which represent fiber and resin respectively. Using this model, the behavior of a [θ/θ]_sym (θ = 15, 30, 45, 60) CFRP cylinder subjected to the lateral compressive load were simulated, and compared with experimental results. The quasi-three-dimensional model is found to be effective for the prediction of the load-displacement curve. For the damage propagation, the transverse crack and interlaminar delamination could be simulated independently. Moreover, the critical strength law using this model was proposed.     

A 22-ns 1-Mbit CMOS high-speed DRAM with address multiplexing

Describes a 1-Mbit high-speed DRAM (HSDRAM), which has a nominal random access time of less than 27 ns and a column access time of 12 ns with address multiplexing. A double-polysilicon double-metal CMOS technology having PMOS arrays inside n-wells was developed with an average 1.3- mu m feature size. The chip has also been fabricated in a 0.9*shrunken version with an area of 67 mm/sup 2/, showing a 22-ns access time. The chip power consumption is lower than 500 mW at 60-ns cycle time. This HSDRAM, which provides SRAM-like speed while retaining DRAM-like density, allows DRAMs to be used in a broad new range of applications.<>