點(diǎn)擊科學(xué)

2012-03-09

封面上是2010年8月日本福島第一核電廠冷卻池中的一根钚鈾混氧燃料棒。2011年3月的一場大海嘯破壞了核電廠的3個(gè)反應(yīng)器，這促使人們不得不重新審視日本在核能方面的安全性及其防災(zāi)準(zhǔn)備手段。

Cooling pool containing a plutonium-uranium mixedoxide fuel rod at Fukushima Dai-ichi nuclear power station， Japan， in August 2010. A tsunami on 11 March 2011 damaged three of the station’s reactors， prompting reassessment of Japan’s reliance on nuclear power and its approach to disaster preparedness.

2012-03-16

封面上是高約8微米的鍺質(zhì)結(jié)晶體偽色掃描電子顯微圖像，立于硅柱體上并由有限的縫隙間隔。在這種結(jié)構(gòu)中，不存在晶片彎折和層面破裂的情況，可以使單晶體與不同的材料整合到同一個(gè)硅襯底上，這種結(jié)構(gòu)可以被用作許多應(yīng)用產(chǎn)品的平臺(tái)，例如多接合點(diǎn)太陽能電池、x線和粒子探測器，或者電力電子設(shè)備等。

False-colored scanning electron micrograph of~8-micrometer-tall germanium crystals， separated by finite gaps， grown onto silicon pillars. In structures like this one， wafer bowing and layer cracking are absent， allowing single-crystal integration of different materials onto a silicon substrate， which serves as a platform for many applications， such as multiplejunction solar cells， x-ray and particle detectors， or power electronic devices.

2012-03-23

春日的陽光為我們指明了光線的傳遞路徑。植物中的UVR8蛋白質(zhì)可以感受到陽光光波中的紫外線-B（UV-B），它可以使植物在生長發(fā)育過程中發(fā)生改變，包括產(chǎn)生一種保護(hù)性的化學(xué)防曬劑。UVR8內(nèi)在的色氨酸環(huán)錐體會(huì)制造出一種內(nèi)置照明開關(guān)，而不需要單獨(dú)的色基。了解植物在不同的光照條件下會(huì)產(chǎn)生何種變化，對于我們?nèi)绾胃玫剡m應(yīng)氣候變化非常重要。

Spring sun lights up signaling pathways. In plants， the UVR8 protein senses ultraviolet-B(UV-B) wavelengths in sunlight， triggering changes in growth and development， including the production of a protective chemical sunscreen. Pyramids of tryptophan rings intrinsic to UVR8 create a built-in light switch; no separate chromophore is required. Understanding how plant growth varies with changes in sunlight becomes more important as we adapt to climate change.

2012-03-30

封面上是2只體長約2毫米的水蚤。左下方的水蚤被一種劇毒的酵母寄生蟲所感染，造成了它亮白色的外觀。宿主與寄生蟲之間內(nèi)在的食物鏈交互作用決定了傳染病的流行程度，同時(shí)也將決定水蚤族群在傳染病流行期間是否變得更具有抗性或是更容易受感染。

Two Daphnia dentifera， each ~2 millimeters long. The organism at bottom left is infected with a virulent yeast parasite， causing her bright white appearance. The food web in which the host-parasite interaction is embedded determines the size of the epidemic， which， in turn， determines whether the Daphnia population becomes more resistant or more susceptible during the epidemic.

（陶 陶 編譯）