美国东部时间9月15日20时，SpaceX公司用猎鹰9号火箭发射载人龙飞船，将4名平民乘客送往太空，开展为期三天的绕地球之旅。这是SpaceX首次全民用、纯商业太空飞行，龙飞船上没有任何专业宇航员。
The Inspiration 4 civilian crew launches from Kennedy Space Center, aboard a SpaceX Falcon 9 rocket. Photograph: Thom Baur/Reuters
这家太空旅馆将在2025年前建成，并在2027年前全面投入运营。
Represented aircraft: Yutu rover
▲ Abstract
▲ 摘要
Theyby: a baby who has been brought up in a gender-neutral way and not outwardly identified by its parents as either a boy or a girl.
“The astronaut will then cast their vote, and the secure, completed ballot is downlinked and delivered back to the County Clerk’s Office by e-mail to be officially recorded,” NASA adds. “The clerk has their own password to ensure they are the only one who can open the ballot. It’s a quick process, and the astronaut must be sure to submit it by 7 pm local time on Election Day if voting as a Texas resident.”
Techlash: a strong and widespread negative reaction to the growing power and influence of large technology companies,particularly those based in Silicon Valley.
Although machine learning bears enormous potential to accelerate developments in homogeneous catalysis, the frequent need for extensive experimental data can be a bottleneck for implementation. Here, we report an unsupervised machine learning workflow that uses only five experimental data points. It makes use of generalized parameter databases that are complemented with problem-specific in silico data acquisition and clustering. We showcase the power of this strategy for the challenging problem of speciation of palladium (Pd) catalysts, for which a mechanistic rationale is currently lacking. From a total space of 348 ligands, the algorithm predicted, and we experimentally verified, a number of phosphine ligands (including previously never synthesized ones) that give dinuclear Pd(I) complexes over the more common Pd(0) and Pd(II) species.
国家航天局同时公布了首次火星探测任务标识“揽星九天”。
作者在超冷的原子气体中用里德堡态代表的自旋系统来演示弗洛奎特工程。通过应用一系列自旋操作，他们改变了有效海森堡XYZ哈密顿量的对称性。因此，总自旋的松弛行为被极大地改变了。
Science, 26 NOVEMBER 2021, VOL 374, ISSUE 6571
https://www.science.org/doi/10.1126/science.abj7478
https://www.science.org/doi/10.1126/science.abd9547
https://www.science.org/doi/10.1126/science.abj0999
https://www.science.org/doi/10.1126/science.abk0634
The roaming chemical reaction mechanism involves near-dissociation of an energized molecule to radicals that leads instead to intramolecular reaction after reorientation at long range. Surprisingly, no clear quantum signatures of roaming have been observed to date, despite the quantum nature of the roaming event. We found evidence of quantum dynamics in the photodissociation of formaldehyde near the roaming threshold. This is ascribed to resonances associated to H+HCO(Ka = 1) that have a profound impact on the CO rotational and translational energy distributions and cause the roaming fraction to vary by a factor of 2 over an energy range of 10 cm–1. The roaming pathway serves both to modulate and report on the complex vibrational dynamics and coupling among the three dissociation pathways in the excited molecule as it decays to products.
野火对晚第四纪食草动物灭绝的全球响应
https://www.science.org/doi/10.1126/science.abj7478
众所周知，草原食草动物通过消耗可能易燃的物质，在限制野火方面发挥着作用。作者提出的证据表明，食草动物-火的相互作用在过去影响了全球范围内的火。他们将晚第四纪大陆层面巨型草食动物灭绝的严重程度与草食生物群落沉积木炭数据计算出的古火活动变化进行了比较。
不同大陆的物种灭绝程度不同，这种模式反映在火灾活动的变化上。在大型食草动物灭绝最严重的地方（南美洲）和灭绝发生最少的地方（非洲），火灾频率增加最多。大型食草动物在第四纪的消失极大地改变了全球的野火状况。
https://www.science.org/doi/10.1126/science.abh2620