Stomatal responses to long-term high vapor pressure deficits mediated most limitation of photosynthesis in tomatoes

Mucilage, a gelatinous substance comprising mostly polysaccharides, is exuded by maize nodal and underground root tips. Although mucilage provides several benefits for rhizosphere functions, studies on the variation in mucilage amounts and its polysaccharide composition between genotypes are still lacking. In this study, eight maize (Zea mays L.) genotypes from different globally distributed agroecological zones were grown under identical abiotic conditions in a randomized field experiment. Mucilage exudation amount, neutral sugars and uronic acids were quantified. Galactose (∼39–42%), fucose (∼22–30%), mannose (∼11–14%), and arabinose (∼8–11%) were the major neutral sugars in nodal root mucilage. Xylose (∼1–4%), and glucose (∼1–4%) occurred only in minor proportions. Glucuronic acid (∼3–5%) was the only uronic acid detected. The polysaccharide composition differed significantly between maize genotypes. Mucilage exudation was 135 and 125% higher in the Indian (900 M Gold) and Kenyan (DH 02) genotypes than in the central European genotypes, respectively. Mucilage exudation was positively associated with the vapor pressure deficit of the genotypes’ agroecological zone. The results indicate that selection for environments with high vapor pressure deficit may favor higher mucilage exudation, possibly because mucilage can delay the onset of hydraulic failure during periods of high vapor pressure deficit. Genotypes from semi-arid climates might offer sources of genetic material for beneficial mucilage traits.

Download Full-text

Study for Nuclide Transfer Ratio of Particles Generated by Thermal Cutting

Volume 5: Safety and Security; Low Level Waste Management, Decontamination and Decommissioning; Nuclear Industry Forum ◽

10.1115/icone14-89139 ◽

2006 ◽

Cited By ~ 1

Author(s):

Yukihiro Iguchi ◽

Tsutomu Baba ◽

Hiroto Kawakami

Keyword(s):

Vapor Pressure ◽

Pressure Tube ◽

Work Place ◽

Nuclear Facilities ◽

Secondary Products ◽

Sampling System ◽

High Vapor Pressure ◽

Transfer Ratio ◽

Thermal Cutting ◽

High Vapor

In dismantling of nuclear facilities, secondary products would disperse into air and water. Thus, it is necessary to assess the effective dose for the public due to the gaseous and liquid radioactive wastes discharged. Especially for the cutting of a highly activated reactor core structures, the material may release special nuclides, some of which can be metal with low melting temperature and relatively high vapor pressure. In this case, the vaporized metal easily transfers to the particles instead of leaving in the dross and would make significant impact to the work place and environment. A pressure-tube type reactor often utilizes zirconium alloy as core structure, which may contains nuclides with high vapor pressure such as radioactive tin or antimony caused by activated tin. In this study, the radioactivity transfer ratio for thermal cutting in air has been investigated by cold tests. The tests have been carried out in an air-tight clean house and used a dust sampling system. The test piece was zirconium and niobium 2.5% alloy with some impurities, which was non-radioactive spare material for the pressure tube of Fugen NPS. Plasma cutting method was carried out with 200 A electric current. The particles were separated by one micrometer size with membrane filters and the material was investigated with an Energy Dispersion X-ray Analyzer (EDX) and the shape of the particle was observed with a Scanning Electron Microscope (SEM). The results showed that there was almost no tin in the dross because most of the tin was evaporated and transferred to aerosol. However, the ratio of zirconium, niobium and iron in the aerosol was not as high as that of tin. The vaporization pressure of antimony is higher than that of tin. The tin can be easily activated by neutron and becomes radioactive antimony. Because Zircalloy-2 or 4 contains ca. 1 percent of tin, irradiated Zircalloy contains significant radioactive antimony (Sb-125). Preparatory analyses showed that the Sb-125 to the environmental impact was comparable with other nuclides. For this reason a test for taking data of the transfer ratio of antimony by using irradiated material has been also carried out.

Download Full-text

Experimental Verification of Water Ingress in a Void by Quick Diffusion at High Reflow Temperature

Volume 5: Electronics and Photonics ◽

10.1115/imece2007-42079 ◽

2007 ◽

Author(s):

Seungbae Park ◽

Haojun Zhang ◽

Changsoo Jang

Keyword(s):

High Temperature ◽

Vapor Pressure ◽

Pressure Sensor ◽

Element Model ◽

High Vapor Pressure ◽

Hygroscopic Properties ◽

Reflow Temperature ◽

Polymer Metal ◽

High Vapor ◽

Underfill Material

The pop-corning failure is known to result from high vapor pressure generation inside cavities at defective interfaces of the electronic package. In order to study the phenomenon, vapor pressure inside a void at high temperature is measured using a specific specimen configuration developed for this purpose. The specimen incorporates a volume-controllable cavity at a polymer-metal interface. A pressure sensor is used to monitor pressure evolution inside the void at high temperature. An underfill material used in the configuration is characterized in terms of hygroscopic properties. The phenomenon is also simulated on a finite element model based on these properties and specimen geometry. The prediction by the numerical model well matches the measurement by pressure sensor. This corroborates the validity of the hypothesis of high vapor pressure employed in numerous existing studies that simulated the pop-corning failure.

Download Full-text