On atmospheric loss of oxygen ions from earth through magnetospheric processes   总被引：1，自引：0，他引：1  

Seki K  Elphic RC  Hirahara M  Terasawa T  Mukai T 《Science (New York, N.Y.)》2001,291(5510):1939-1941

In Earth's environment, the observed polar outflow rate for O(+) ions, the main source of oxygen above gravitational escape energy, corresponds to the loss of approximately 18% of the present-day atmospheric oxygen over 3 billion years. However, part of this apparent loss can actually be returned to the atmosphere. Examining loss rates of four escape routes with high-altitude spacecraft observations, we show that the total oxygen loss rate inferred from current knowledge is about one order of magnitude smaller than the polar O(+) outflow rate. This disagreement suggests that there may be a substantial return flux from the magnetosphere to the low-latitude ionosphere. Then the net oxygen loss over 3 billion years drops to approximately 2% of the current atmospheric oxygen content.  相似文献   

Asynchronous climate changes in the North Atlantic and Japan during the last termination     

Nakagawa T  Kitagawa H  Yasuda Y  Tarasov PE  Nishida K  Gotanda K  Sawai Y;Yangtze River Civilization Program Members 《Science (New York, N.Y.)》2003,299(5607):688-691

Pollen records from the annually laminated sediment sequence in Lake Suigetsu, Japan, suggest a sequence of climate changes during the Last Termination that resembles that of the North Atlantic region but with noticeable differences in timing. An interstadial interval commenced a few centuries earlier [approximately 15,000 years before the present (yr B.P.)] than the North Atlantic GI-1 (B?lling) event. Conversely, the onset of a Younger Dryas (YD)-like cold reversal (12,300 to 11,250 yr B.P.) postdated the North Atlantic GS-1 (YD) event by a few centuries. Climate in the Far East during the Last Termination reflected solar insolation changes as much as Atlantic influences.  相似文献   

Impact of nutrient enrichment in a waterchestnut ecosystem at Takahama-iri Bay of Lake Kasumigaura,Japan     

Hidekazu Yamamoto  Humitake Seki 《Water, air, and soil pollution》1979,12(4):503-510

Waterchestnut was shown to be one of the most efficient agents to yield photosynthetic products among aquatic plants in littoral vegetation. Though the plant can be an agent to remove nutrient in agricultural and domestic wastes directly through its waterroots to some extent, waterchestnut plays a great role in removing nutrients through its roots from lake sediments to watercolumn of the lake. Waterchestnut can be choked to death when its leaves are covered completely by the heavy blue-green algal bloom typical in hypereutophic lakes.  相似文献   

Effect of rapid oligotrophication by an aquatic treatment pilot plant on the microbial community of a mesotrophic Bog     

Takeshi Naganuma  Humitake Seki 《Water, air, and soil pollution》1988,42(3-4):387-396

Rapid oligotrophication by the operation of the ‘Bio-filter system’ has changed Doh-Hoh-Numa Bog from a moderate mesotrophic system to the oligotrophic end of such a system. However, the population growth rate of the bacterioplankton community was little affected, and continued to be controlled primarily by the DOC concentration even after the system operation. This DOC concentration was higher during the operation period, although environmental factors relevant to primary production were shifted to the direction of oligotrophication. The natural bacterioplankton community in the bog was shown to modify its physiological kinetics to maintain the growth rate at the optimal level, even when it was exposed to oligotrophication processes with the operation of the ‘Bio-filter system’.  相似文献   

Paraticulate metals in waters of a typical irrigation river: The River Sakuragawa,Japan     

Humitake Seki  Masayuki Takahashi  Katsumi Kobayashi  Shozo Ishizaka 《Water, air, and soil pollution》1979,12(2):265-271

The particulate metallic elements in waters of a water system of the River Sakuragawa and Lake Kasumigaura were measured by the multielement analyses using particle-induced X-ray emission. The heavy metal particulates for environmental standards were less than 0.0001 ppm for Cd, 0.00037 ppm for Cr, and 0.00078 ppm both for Hg and Pb in the river waters. The predominant metal particles in the waters were Fe, Mn, and Zn.  相似文献   

Quercetin-4'-glucoside is more potent than quercetin-3-glucoside in protection of rat intestinal mucosa homogenates against iron ion-induced lipid peroxidation     

Murota K  Mitsukuni Y  Ichikawa M  Tsushida T  Miyamoto S  Terao J 《Journal of agricultural and food chemistry》2004,52(7):1907-1912

Quercetin is a typical antioxidative flavonoid found in vegetables, which is more commonly present as its glucosides, quercetin-3-glucoside (Q3G) and quercetin-4'-glucoside (Q4'G). The main aim of this study was to estimate the antioxidant activity of Q3G and Q4'G on iron ion-driven lipid peroxidation of the gastrointestinal mucosa. Q4'G markedly suppressed the lipid peroxidation when rat gastrointestinal mucosa homogenates were incubated with Fe(NO3)3 and ascorbic acid. Its effectiveness was greater as compared to that of Q3G and comparable to that of quercetin aglycone. Furthermore, Q4'G yielded higher amounts of quercetin aglycone than Q3G on incubation with the homogenates. However, Q4'G showed a lower chelating activity in comparison to Q3G. These results indicate that Q4'G, even though it has a low chelating activity, because of its efficient conversion to antioxidative aglycone on exposure to the mucosa, can act as a powerful antioxidant on iron ion driven lipid peroxidation in the intestinal mucosa. Thus, vegetables rich in Q4'G, such as onion, are likely to serve as favorable antioxidant sources for suppressing iron-induced oxidative stress in the intestinal tract.  相似文献   

Improvement of the emulsifying properties of porcine sarcoplasmic proteins with a low-molecular weight surfactant by the two-step emulsification method     

Yuji MIYAGUCHI  Yuki HAYASHI  Kiyomi NAGAYAMA 《Animal Science Journal》2003,74(2):145-151

The emulsifying properties of porcine sarcoplasmic protein (SP) with or without low-molecular weight surfactants were examined. The emulsifying activity (EA) of SP was weaker than that of sodium caseinate (CA), blood plasma (BP) and whey protein isolates at a protein concentration of 0.5–3%. Sodium chloride decreased the EA of SP. The EA of SP was about one quarter that of CA in the presence of 3% sodium chloride. As homogenization time increased, the EAs of SP and BP decreased. The EA of SP was not influenced by sucrose stearate ester (SE) with a hydrophilic-lipophilic balance (HLB) value of 16 (SE-16) but was decreased by those with HLB values of 5 and 1. Low-molecular weight surfactants such as SE-16, Tween 80 and sodium cholate improved the EA of SP with the two-step emulsification method: corn oil was previously emulsified with the surfactant before addition of SP and homogenization. In the case of the addition of SE-16 as primary emulsifier, the EA was about twice as high as that of SP alone. The same effect was shown in the emulsions formed by CA and soy protein isolate. These results indicate that the emulsifying properties of meat protein would be improved by the addition of a low-molecular weight surfactant in a two-step emulsification.  相似文献   

Precise, simple screening for resistance in potato varieties to common scab using paper pots     

Akira Kobayashi  Shigeo Naito  Yuki O. Kobayashi  Shogo Tsuda  Akiko Ohara-Takada  Motoyuki Mori 《Journal of General Plant Pathology》2005,71(2):139-143

Resistance to common scab pathogen Streptomyces turgidiscabies of seven potato varieties was compared in the field with a newly developed paper pot method. Seedlings raised in soil in paper pots containing inocula at 1 × 10³ to 10⁷cfu/g soil were transplanted into a scab-free field and grown for 3 months. The disease severity of the seven varieties in the field trials differed in iteration and from year to year, even though their resistance levels were approximately similar at the expected levels. With the paper pot method, the seven varieties had different resistance levels, which were almost completely consistent with the results of the field trials, at more than 1 × 10⁵cfu/g soil. Significant differences in disease severity between resistant and susceptible varieties were observed (P = 0.05) for 2 years, and the resistance level of the varieties was elucidated.  相似文献   

Fine surface structure of bovine acrosome-intact and reacted spermatozoa observed by atomic force microscopy     

Saeki K  Sumitomo N  Nagata Y  Kato N  Hosoi Y  Matsumoto K  Iritani A 《The Journal of reproduction and development》2005,51(2):293-298

The atomic force microscope (AFM) provides nanometer resolution, topographic data of the natural surface structure of materials. We studied the topology of the surface structure of bovine sperm heads during the acrosome reaction by AFM. In addition, we numerically analyzed the areas of the median sagittal plane of the sperm heads. Bovine frozen-thawed spermatozoa were washed, capacitated by heparin, and incubated with lysophosphatidylcholine (LPC) to induce the acrosome reaction, smeared on a cover glass, air-dried, and observed with AFM using the dynamic force (tapping) mode. AFM analysis of spermatozoa showed the clear surface structure of acrosomes, equatorial segments, postacrosomal regions and necks. Although AFM images of spermatozoa capacitated by heparin had complete acrosomes, most spermatozoa treated with LPC had no acrosomal caps as shown by AFM. These observations coincided with those obtained by light microscopy after staining with naphthol yellow S and erythrosin B. Furthermore, numerical analysis of AFM images indicated that areas of the median sagittal plane of the anterior portions of acrosome-reacted sperm heads (2679 +/- 616 pixels) were approximately 40% less than those of intact heads (4535 +/- 174 pixels, P<0.05). These results indicate that AFM can usefully observe and numerically analyze the fine surface structures of bovine spermatozoa.  相似文献   

The presence of a short form of p53 in chicken lymphoblastoid cell lines during apoptosis     

Takagi M  Takeda T  Asada Y  Sugimoto C  Onuma M  Ohashi K 《The Journal of veterinary medical science / the Japanese Society of Veterinary Science》2006,68(6):561-566

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