Compression of Ice to 210 Gigapascals: Infrared Evidence for a Symmetric Hydrogen-Bonded Phase

Protonated and deuterated ices (H2O and D2O) compressed to a maximum pressure of 210 gigapascals at 85 to 300 kelvin exhibit a phase transition at 60 gigapascals in H2O ice (70 gigapascals in D2O ice) on the basis of their infrared reflectance spectra determined with synchrotron radiation. The transition is characterized by soft-mode behavior of the nu3 O-H or O-D stretch below the transition, followed by a hardening (positive pressure shift) above it. This behavior is interpreted as the transformation of ice phase VII to a structure with symmetric hydrogen bonds. The spectroscopic features of the phase persisted to the maximum pressures (210 gigapascals) of the measurements, although changes in vibrational mode coupling were observed at 150 to 160 gigapascals.     

不同转基因番茄GalUR的表达与Vc含量

为了得到高维生素C（Vc）含量新品种,克隆和构建了GalUR半乳糖醛酸还原酶基因,并转入了番茄.通过不同转基因突变体GalUR基因表达和Vc含量分析发现：GalUR基因在转GalUR基因番茄中得到了过量表达;在转FRO2-铁还原酶基因的番茄突变体中表达量增加了60%;在耐贮藏转基因番茄F3、F2、F1中也均高于对照,其中F3的表达量最高,是对照的2～3倍;在非转基因中蔬4号和6号的表达量高于丽春番茄1倍;所有供试GalUR基因表达量均为红果最多、粉红果次之,青果最少.转基因番茄果实Vc含量变化与上述GalUR基因的表达有相同规律.转GalUR3基因番茄果实和叶片Vc含量高于对照2倍以上.GalUR基因的表达还与乙烯合成酶基因ACS、CTR1和铁还原酶FRO2基因的表达有关.     

Laser 40Ar/39Ar Evaluation of Slow Cooling and Episodic Loss of 40Ar from a Sample of Polymetamorphic Muscovite

Volume diffusion models predict that crystals with large diffusion dimensions can record a wide range of thermal conditions in the Earth's crust. Direct measurements of the zoning of radiogenic argon-40 in single muscovite porphyroblasts, from a complex terrain in the Vermont Appalachians, record multiple crustal events that span 150 million years. The crystal radius was the effective dimension for argon diffusion (approximately 1000 micrometers). Late deformation features inside the crystals locally decreased the diffusion dimension and promoted loss of argon-40. Zoning patterns of radiogenic isotopes, as observed in this study, are an increasingly important diagnostic tool for studying the thermal record of tectonic processes.     

Scanning Single-Electron Transistor Microscopy: Imaging Individual Charges

A single-electron transistor scanning electrometer (SETSE)-a scanned probe microscope capable of mapping static electric fields and charges with 100-nanometer spatial resolution and a charge sensitivity of a small fraction of an electron-has been developed. The active sensing element of the SETSE, a single-electron transistor fabricated at the end of a sharp glass tip, is scanned in close proximity across the sample surface. Images of the surface electric fields of a GaAs/AlxGa1-xAs heterostructure sample show individual photo-ionized charge sites and fluctuations in the dopant and surface-charge distribution on a length scale of 100 nanometers. The SETSE has been used to image and measure depleted regions, local capacitance, band bending, and contact potentials at submicrometer length scales on the surface of this semiconductor sample.     

The Interdependence of Deformational and Thermal Processes in Mountain Belts

Crustal temperatures within collisional orogens are anomalously high compared with temperatures at comparable depths in stable continents, which is evidence of thermal processes that are fundamental to orogenesis. These temperatures can be explained by the redistribution of crust enriched in heat-producing elements through the accretion of crust from the down-going plate to the upper plate and surface erosion. With the use of geologically reasonable rates, the model results predict high temperatures (over 600°C) and inverted upper-plate geotherms (about 100°C over 20 kilometers) at shallow depths (20 to 40 kilometers) by 25 to 35 million years after collision. This study emphasizes the interdependence of deformational, surficial, and thermal processes.     

Gene expression levels of growth hormone receptor and insulin-like growth factor-I in gonads of maturing coho salmon (Oncorhynchus kisutch)

The expression levels of growth hormone receptor (GHR) and insulin-like growth factor (IGF-I) in gonads of maturing coho salmon were measured by real-time PCR. The GHR and IGF-I mRNAs showed different gene expression pattern between male and female. These results suggest that a sexual dimorphism may exist in the GHR and IGF-I mRNA expressions of coho salmon during gonadal maturation