Lead isotopic ages of chondrules and calcium-aluminum-rich inclusions

The lead-lead isochron age of chondrules in the CR chondrite Acfer 059 is 4564.7 +/- 0.6 million years ago (Ma), whereas the lead isotopic age of calcium-aluminum-rich inclusions (CAIs) in the CV chondrite Efremovka is 4567.2 +/- 0.6 Ma. This gives an interval of 2.5 +/- 1.2 million years (My) between formation of the CV CAIs and the CR chondrules and indicates that CAI- and chondrule-forming events lasted for at least 1.3 My. This time interval is consistent with a 2- to 3-My age difference between CR CAIs and chondrules inferred from the differences in their initial 26Al/27Al ratios and supports the chronological significance of the 26Al-26Mg systematics.     

Meteorite phosphates show constant 176Lu decay rate since 4557 million years ago

The use of radioactive decay of 176Lu to 176Hf to study the evolution of the Earth requires a precise and accurate value for the 176Lu decay constant. Recent determinations of this decay constant by age comparison to the more precisely calibrated U-Pb isotopic system produced internally consistent but discrepant values between terrestrial minerals and meteorites. New highly radiogenic Lu-Hf data for phosphate minerals from Richardton (ordinary chondrite) and Acapulco (primitive achondrite) yield decay constant values of 1.864 x 10(-11) +/- 0.016 x 10(-11) and 1.832 x 10(-11) +/- 0.029 x 10(-11) year(-1), respectively, identical to the value determined from terrestrial minerals.     

Neural mechanisms of visual attention: how top-down feedback highlights relevant locations

Attention helps us process potentially important objects by selectively increasing the activity of sensory neurons that represent the relevant locations and features of our environment. This selection process requires top-down feedback about what is important in our environment. We investigated how parietal cortical output influences neural activity in early sensory areas. Neural recordings were made simultaneously from the posterior parietal cortex and an earlier area in the visual pathway, the medial temporal area, of macaques performing a visual matching task. When the monkey selectively attended to a location, the timing of activities in the two regions became synchronized, with the parietal cortex leading the medial temporal area. Parietal neurons may thus selectively increase activity in earlier sensory areas to enable focused spatial attention.     

Self-assembly of large and small molecules into hierarchically ordered sacs and membranes

We report here the self-assembly of macroscopic sacs and membranes at the interface between two aqueous solutions, one containing a megadalton polymer and the other, small self-assembling molecules bearing opposite charge. The resulting structures have a highly ordered architecture in which nanofiber bundles align and reorient by nearly 90 degrees as the membrane grows. The formation of a diffusion barrier upon contact between the two liquids prevents their chaotic mixing. We hypothesize that growth of the membrane is then driven by a dynamic synergy between osmotic pressure of ions and static self-assembly. These robust, self-sealing macroscopic structures offer opportunities in many areas, including the formation of privileged environments for cells, immune barriers, new biological assays, and self-assembly of ordered thick membranes for diverse applications.     

Larval performances and life cycle completion of the Siberian moth, <Emphasis Type="Italic">Dendrolimus sibiricus</Emphasis> (Lepidoptera: Lasiocampidae), on potential host plants in Europe: a laboratory study on potted trees

The Siberian moth, Dendrolimus sibiricus, Tschtv. is the most harmful defoliator of coniferous forests in North Asia. The pest has already spread over the Urals and continues moving westwards. Recently, it has been recommended for quarantine in member countries by European and Mediterranean Plant Protection Organization (EPPO). The performances of the pest on coniferous species planted in Europe were assessed on a range of potted trees corresponding to the spectrum of economically important conifers in the EU: European larch Larix decidua, Norway spruce Picea abies, Scots pine Pinus sylvestris, European black pine Pinus nigra, and the North American species: Douglas fir Pseudotsuga menziesii and grand fir Abies grandis. Larvae showed a potential to survive and complete the development on all these host tree species. Favorable hosts were grand fir, European larch, and Douglas fir that allowed higher survival, better larval development, and as a result, yielded heavier pupae and adult moths with higher longevity. Black pine was a poor host but, however, could still support larval and pupal development. Norway spruce and Scots pine had an intermediate behavior. If accidentally introduced to Europe, the Siberian moth may become especially damaging in forest stands predominated by European larch and by the North American firs. Norway spruce and especially the two-needle pines will be less prone to intensive defoliation by this species. The fact that the pest may damage the range of economically important coniferous species should be taken into account in the pest risk assessment for Europe and also for North America where the Siberian moth occurrence is considered likely.     

Antioxidative activity in the pericarp and seed of Japanese pepper (Xanthoxylum piperitum DC)

The antioxidative activity of the dried pericarp and seed of Japanese pepper was studied. The ethyl acetate extract from the pericarp and the methanol extract from the seed showed strong antioxidative activity against linoleic acid by the ferric thiocyanate and thiobarbituric acid (TBA) methods. Japanese pepper contained 3.9 and 2.9 mg/100 g of dry weight (dw) of tocopherols in the pericarp and seed, respectively, alpha-Toc in the former constituting 82% of total tocopherol and gamma-Toc in the latter constituting 96%. Arbutin and magnoflorine were isolated as antioxidants and their chemical structures determined by instrumental analyses. The contents of arbutin evaluated as the trifluoroacetate derivative by GC-MS were 35 and 3.0 mg/100 g of dw in the pericarp and seed, respectively. Magnoflorine was present only in the seed, and not in the pericarp. Both arbutin and magnoflorine exhibited antioxidative activity against linoleic acid and radical-scavenging activity against the DPPH radical.     

‘巨峰’葡萄主梢和副梢花器官与种子发育的研究

 ‘巨峰’葡萄主梢花粉粒大于副梢, 花粉染色率与副梢差异不显著, 发芽率低于副梢, 但花粉发芽率不影响种子的形成。主梢小花雌蕊在减数分裂后形成的功能大孢子小于副梢。同时开花前主梢胚囊的发育状况优于副梢, 开花期正常胚囊率主梢也明显低于副梢。因此, 开花前后主梢异常胚囊的出现是导致受精发生障碍并使结籽率低下的原因。