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In nature, when hazardous geophysical granular flows (e.g. a snow avalanche) impact on an obstacle as they stream down a slope, rapid changes in flow depth, direction and velocity will occur. It is important to understand how granular material flows around such obstacles in order to enhance the design of defense structures. In this study, a three dimensional (3-D) Smoothed Particle Hydrodynamics (SPH) model is developed to simulate granular flow past different types of obstacles. The elastic–perfectly plastic model with implementation of the Mohr–Coulomb failure criterion is applied to simulate the material behavior, which describes the stress states of soil in the plastic flow regime. The model was validated by simulating the collapse of a 3-D column of sand with two different aspect ratios; the results showed that the SPH method is capable of simulating granular flow. The model is then applied to simulate the gravity-driven granular flow down an inclined surface obstructed by a group of columns with different spacing, a circular cylinder and a tetrahedral wedge. The numerical results are then compared with experimental results and two different numerical solutions. The good agreements obtained from these comparisons demonstrate that the SPH method may be a powerful method for simulating granular flow and can be extended to design protective structures.
This paper considers the possible commercial viability of applying the moving particle semi-implicit (MPS) method to avalanches. The MPS method is a powerful tool for reproducing the flow phenomenon with large-scale surface deformation. In order to apply this method to snow avalanches, we modified the original model to introduce constitutive equations of Bingham fluid, dilatant fluid and the erosion–deposition process. The modified model was applied to some cases and evaluated through comparison with experimental results and observed data.
During fertilisation of a fully mature oocyte, the sperm intrinsic nuclear envelope (SINE) disappears soon after sperm-oocyte fusion. A new nuclear envelope appears around the decondensed sperm chromatin when the oocyte reaches telophase II. Whether the SINE persists or rapidly disappears after sperm entery into immature oocytes or fertilised eggs has been controversial. Nuclear envelopes have been demonstrated around the sperm chromatin, which cannot be decondensed within the ooplasm of these oocytes or eggs, but whether these envelopes are persisting SINEs or newly formed envelopes has been apoint of dispute. To resolve this issue, the fate of the germinal vesicle stage(GV oocytes) or fertilised eggs at the pronuclear stage(PN eggs). The SINEs disappeared quikly within these oocytes or eggs, like those within maturing or mature oocytes, suggesting that the envelops around the sperm chromatin must be newly formed after SINE breakdown. To obtain further evidence, a detergent-treated, SINE-free sperm nucleus was injected into a PN egg. A new envelope appeared around the still-condensed or partially decondensed sperm chromatin within 3h after injection. Thus, disassembly of the SINE within ooplasm, unlike that of nuclear envelopes of other cells at prophase, is independent of the cell cycle stage of the oocyte or egg, whereas the ability of the ooplasm to assemble the new envelope is restricted to certain periods of the cycle. i.e. early prophase and telophase during meiosis and interphase, periods when active M-phase Promoting factor (MPF) is absent from the ooplasm.
The reasons why the open circuit voltage (Voc) of high-x CuIn1-xGaxSe2 (CIGS)/ZnO solar cells remain low are discussed. Here it is shown that the Voc ceiling can be interpreted simply on the basis of a model that the valence-band energy (Ev) of CIGS is almost immovable irrespective of x. When the conduction-band energy (Ec) of ZnO is lower than that of high-x CIGS (DEc<0), the built-in potential (Vbi) of a CIGS/ZnO junction is equivalent to the flat-band potential (Vbi) that arises from the separation between the Fermi energies of the two materials. If the Ev (and therefore the Fermi energy) of p-type CIGS is constant with increasing x, the Vbi and Voc that follows the Vbi remain unchanged since the Fermi energy of ZnO is constant. This unchangeable Voc reduces the conversion efficiency of high-x CIGS cells in cooperation with reduced photocurrents due to a larger bandgap. A positive offset, ΔEc>o gives rise to a photoelectrons barrier in the conduction-band that partially cancels Voc, thus the Voc of a low-x CIGS cell is governed by the Ec of CIGS. Based upon this concept, a material selection guideline is given for the windows and transparent electrodes appropriate for high-x CIGS absorbers-based solar cells.
Using EBIC and EDX measurements, CIGS solar cells prepared under several different conditions were observed and characterized. The results of EBIC and EDX measurements suggest that Cd plays an important role in the forming of a buried pn-junction in the CIGS layer via diffusion, and de-emphasize the possibility of the formation of the hetero pn-junction at the CdS/CIGS heterointerface. The correlation of the extent of the space charge region and the observed shift in the pn-junction location with the diffusion of the constituent elements in CIGS was investigated.
We have fabricated CIGS:Fe polycrystalline thin films using a standard three-stage method, and investigated the effects of Fe doping on cell performances. The Ga / (In+Ga) ratio was varied between 0.3 ˜ 1.0 (= CGS), and the Fe concentration was varied between 0.0 ˜ 1.2 mol%. The films were characterized by various means, including the cell performance. Increment of the grain size with higher Fe content was observed. Redshift with higher Fe content was observed in the absorbance spectra. The spectral response of the fabricated solar cells deteriorated with higher Fe content, from the long wavelength side.
We report a rare case of relapsing polychondritis with an initial symptom of inner ear involvement. This 53-year-old Japanese man experienced a hearing difficulty, tinnitus in both ears, and dizziness of sudden onset, but lacked auricular chondritis at that time, which is the most frequent finding in relapsing polychondritis. Thus it was difficult to reach a correct diagnosis. Steroid therapy, with oral prednisolone 15 mg daily, was effective. Almost two months after we began the steroid therapy, the patient complained of losing interest in his work and reported a hallucination vision on the TV screen, so the dose of prednisolone was decreased to 10 mg. The hallucinations then disappeared, but the serum level of C-reactive protein increased highly. To reduce the dose of prednisolone, we tried low-dose oral methotrexate. However, we had to discontinue it when the patient experienced severe vomiting and diarrhoea. As adjuvant therapy, we then administered Sho-saiko-to, Chinese herbal medicines with few side effects. Symptoms and laboratory abnormalities then improved markedly.
Pseudoaneurysms of the extracranial carotid arteries are rarely seen following irradiation for cancers of the head and neck. We present a patient with a pseudoaneurysm of the common carotid artery following a radical neck dissection and irradiation for thyroid carcinoma 20 years earlier. Following oesophagoscopical examination, a pseudoaneurysm of the right common carotid artery ruptured into the piriform sinus. The common carotid artery was embolized with multiple coils and the bleeding was halted. The relationship between the carotid artery aneurysm and irradiation, and the treatment of carotid artery aneurysm, is discussed.
Cowden's disease is characterized by multiple hamartomas and neoplasias of ectodermal, mesodermal and endodermal origin. A case of a 22-year-old man suffering from nocturnal dyspnoea is reported. The patient had a large number of hyperkeratotic, lichenoid papules, scattered over the right side of the trunk, back and palm. In his oral cavity, papules were present on the gingiva and hard palate. The patient was operated on for tonsillar hypertrophy and for excluding the possibility of malignant lymphoma. An examination of immunophenotypes of the palatal tonsil lymphocytes revealed B-cell proliferation and poly-clonal immunoglobulin.
Angiosarcoma of the nasal cavity is extremely rare. We present a case of angiosarcoma of the nasal cavity in an eight-yearold boy. He was treated with medial maxiUectomy via lateral rhinotomy. The histological diagnosis was confirmed by immunohistological stain with Factor Vlll-like antigen. Magnetic resonance imaging (MRI) was useful in determining the extent of the tumour.
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