Agglomeration Characteristics of Aluminum Particles in AP/AN Composite Propellants

Most solid rockets are powered by ammonium perchlorate (AP) composite propellant including aluminum particles. As aluminized composite propellant burns, aluminum particles agglomerate as large as above 100 μm diameter on the burning surface, which in turn affects propellant combustion characteristics. The development of composite propellants has a long history. Many studies of aluminum particle combustion have been conducted. Optical observations indicate that aluminum particles form agglomerates on the burning surface of aluminized composite propellant. They ignite on leaving the burning surface. Because the temperature gradient in the reaction zone near a burning surface influences the burning rate of a composite propellant, details of aluminum particle agglomeration, agglomerate ignition, and their effects on the temperature gradient must be investigated. In our previous studies, we measured the aluminum particle agglomerate diameter by optical observation and collecting particles. We observed particles on the burning surface, the reaction zone, and the luminous flame zone of an ammonium perchlorate (AP)/ammonium nitrate (AN) composite propellant. We confirmed that agglomeration occurred in the reaction zone and that the agglomerate diameter decreased with increasing the burning rate. In this study, observing aluminum particles in the reaction zone near the burning surface, we investigated the relation between the agglomerates and the burning rate. A decreased burning rate and increased added amount of aluminum particles caused a larger agglomerate diameter. Defining the extent of the distributed aluminum particles before they agglomerate as an agglomerate range, we found that the agglomerate range was constant irrespective of the added amount of aluminum particles. Furthermore, the agglomerate diameter was ascertained from the density of the added amount of aluminum particles in the agglomerate range. We concluded from the heat balance around the burning surface that the product of the agglomerate range and the burning rate was nearly constant irrespective of the added amount of aluminum particles. Moreover, the reduced burning rate increased the agglomerate range.     

Diet-induced changes in alginate- and laminaran-fermenting bacterial levels in the caecal contents of rats

Brown algae contain soluble polysaccharides, such as alginic acid, fucoidan and laminaran. To assess the induction of dietary fiber-fermenting bacteria in the intestine, rats were fed diet containing no dietary fiber (control) or 2% w/w of the polysaccharides for 2 weeks. The levels of dietary fiber-fermenting bacteria in caecal contents were determined using decimal dilution culture containing 1% w/v of the fibers. Caecal microbiota in the rats was analyzed using polymerase chain reaction (PCR)-denaturing gradient gel electrophoresis (DGGE). In the culture method, 4–9 log viable cells/g caecal content of alginate-fermenting bacteria was detected in rats fed alginate, while this was not detected in rats fed the control diet. Although laminaran-fermenting bacteria were detected in control rats (4–9 log viable cells/g), the level observed in rats fed laminaran was 8 or 9 log viable cells/g. On the other hand, fucoidan-fermenting bacteria were not detected in rats fed fucoidan. DGGE analysis showed laminaran administration increased the diversity of bacterial bands. Clostridium spp. and Parabacteroides distasonis were detected as typical species in rats fed alginate and laminaran. The results indicate that the intake of soluble fermentable fibers in edible brown algae can alter the intestinal microbiota and its fermentation capacity.     

Angiotensin I-converting enzyme inhibitory activities of Chinese fermented soypaste and estimation of the inhibitory substances

Angiotensin I-converting enzyme (ACE) inhibitory activities of aqueous extracts of Chinese commercial soypaste were investigated in this work. Six samples from northern China showed potent ACE inhibitory activities with IC₅₀ values less than 40.0 μg/mL. ACE inhibitors in the sample with the strongest activity were purified by ultrafiltration, solid-phase extraction and gradient RP-HPLC. According to spectroscopic methods, a compound (M328.1) was separated as C₁₅H₂₁NO₇. It was supposed to be a conjugate of phenylalanine and glucose generated by Maillard reaction during soypaste production, providing support on the contribution of Maillard reaction products to the ACE inhibitory activity of the sample. Results further indicated that the total ACE inhibition by the sample occurred from the combined function of various bioactive substances, suggesting that Chinese soypaste could be a good source of ACE inhibitors for exploring functional foods or ingredients with antihypertensive effect.     

不同波长UV对副溶血性弧菌光修复反应的影响

低压水银管是常见的灭菌工具,其一般采用的是波长为254 nm的UVC作为灭菌光源。而UVA（365 nm波长）配合发光二极管（light-emitting diodes,LED）也有明显的杀菌效果。本研究从灭菌能力,照射后细菌的光修复能力和再生长能力以及能耗等方面入手,比较短波长的UVC和长波长的UVA/LED对副溶血性弧菌的灭菌效果。结果显示,UVA/LED比UVC有更强的杀菌能力,且在受到UVA/LED照射后,副溶血性弧菌的再生长明显慢于单纯UVC处理后的细菌;对副溶血性弧菌的光修复酶基因表达水平进行检测发现,UVA/LED照射后副溶血性弧菌三种光修复酶基因的表达水平都无激活现象,而UVC处理后的细菌三种基因表达水平明显升高。我们认为UVA/LED可能抑制副溶血性弧菌的光修复现象。但在具备以上优势的同时,UVA/LED的能耗大大高于UVC,因此该技术还有待进一步改进。     

Localized amyloidosis in squamous cell carcinoma of uterine cervix: electron microscopic features of nodular and star-like amyloid deposits

An ultrastructural study of amyloid deposits in four cases of squamous cell carcinoma of uterine cervix was performed. The amyloid deposits reacted with anti-keratin antiserum on frozen sections. Amyloid deposits showed nodular (4 cases) and star-like forms (3 cases). Nodular amyloid deposits were composed of slightly whorled fibrils, measuring 7-10 nm in width. Some of them contained cellular debris and thicker, more electron-dense filaments than amyloid fibrils. In three cases, filamentous tumour cells and filamentous masses were observed together with amyloid. Star-like amyloid deposits were composed of bundles of straight amyloid fibrils. Some of the tumour cells in contact with star-like amyloid deposits had deep cytoplasmic invaginations, where closely packed amyloid fibrils were arrayed in parallel fashion. In addition, a few tumour cells had membrane-bound amyloid fibrils in the cytoplasm. It is suggested that nodular amyloid deposits are derived from the tumour cells through filamentous degeneration. Amyloid fibrils in star-like amyloid deposits are thought to be formed within the cytoplasm or in the vicinity of invaginated cytoplasmic membranes of the tumour cells.     

Adhesion between side surface of an elastic beam and flat surface of a rigid body

A theory of adhesion between an elastic beam and a rigid body is proposed using linear beam theory. Normalized force between the elastic beam and the rigid body considering adhesion of the side surface of the elastic beam is investigated theoretically. Adhesion of an elastic beam is important to analyze gecko adhesion, and peeling mechanism of an adhered film. This adhesion is also important in design of grip-and-release devices. The force between an elastic beam and a rigid body is investigated by considering shear force and total energy, and is obtained as a function of the displacement of the elastic beam. The proposed theory is different from Kendall’s thin-film peeling theory in terms of the elastic energy. The proposed theory considers bending elastic energy, whereas Kendall’s theory considers extension elastic energy. Two different contacts, line contact and area contact, are taken into account to discuss the loading and unloading processes in terms of the relation between the force and the displacement. Non-dimensional parameter, which relates to the work of adhesion and the specifications of the elastic beam, is introduced to explain the normalized maximum tensile force.     

Effect of leakage current through ferroelectric and insulator on retention characteristics of metal-ferroelectric-insulator-semiconductor structure

Abstract

Retention characteristics of MFIS (metal-ferroelectric-insulator-semiconductor) structures have been investigated theoretically and experimentally. The simulated retention characteristics have indicated that reducing current through the ferroelectric layer is very effective to make the retention time long. In order to reduce the current through the ferroelectric layer, an MFIS with an improved ferroelectric layer and an M-I-FIS (metal-insulator-ferroelectric-insulator-semiconductor) have been investigated theoretically. Both of them have given good retention characteristics. Experimentally, retention characteristics of MFIS have been much improved by annealing, which is considered to suppress the current density in the ferroelectric layer, although those of M-I-FIS have been improved a little.     

Application of energy capacitor system to wind power generation

In this paper, it is reported that energy capacitor system (ECS), which combines power electronic devices and electric double‐layer capacitor, can significantly decrease voltage and power fluctuations of grid‐connected fixed‐speed wind generator. The proper selection of wind farm output power reference is still a problem for smoothing the wind farm output power. This paper proposes exponential moving average to generate the reference output power of a grid‐connected wind farm. The objective of the control system is to follow the line power reference by absorbing or providing real power to or from the ECS. Moreover, the necessary reactive power can also be supplied to keep the wind farm terminal voltage at the desired reference level. Real wind speed data were used in the simulation analyses, which validate the effectiveness of the proposed control strategy. Simulation results clearly show that our proposed ECS can be suitable for wind power application. Copyright © 2007 John Wiley & Sons, Ltd.