The Climate Absolute Radiance and Refractivity Observatory (CLARREO) mission will provide a calibration laboratory in orbit for the purpose of accurately measuring and attributing climate change. CLARREO measurements establish new climate change benchmarks with high absolute radiometric accuracy and high statistical confidence across a wide range of essential climate variables. CLARREO's inherently high absolute accuracy will be verified and traceable on orbit to Système Internationale (SI) units. The benchmarks established by CLARREO will be critical for assessing changes in the Earth system and climate model predictive capabilities for decades into the future as society works to meet the challenge of optimizing strategies for mitigating and adapting to climate change. The CLARREO benchmarks are derived from measurements of the Earth's thermal infrared spectrum (5–50 μm), the spectrum of solar radiation reflected by the Earth and its atmosphere (320–2300 nm), and radio occultation refractivity from which accurate temperature profiles are derived. The mission has the ability to provide new spectral fingerprints of climate change, as well as to provide the first orbiting radiometer with accuracy sufficient to serve as the reference transfer standard for other space sensors, in essence serving as a “NIST [National Institute of Standards and Technology] in orbit.” CLARREO will greatly improve the accuracy and relevance of a wide range of space-borne instruments for decadal climate change. Finally, CLARREO has developed new metrics and methods for determining the accuracy requirements of climate observations for a wide range of climate variables and uncertainty sources. These methods should be useful for improving our understanding of observing requirements for most climate change observations

Dangerous organophosphorus (OP) compounds have been used as insecticides in agriculture and in chemical warfare. Because exposure to OP could create a danger for humans in the future, butyrylcholinesterase (BChE) has been developed for prophylaxis to these chemicals. Because it is impractical to obtain sufficient quantities of plasma BChE to treat humans exposed to OP agents, the production of recombinant BChE (rBChE) in milk of transgenic animals was investigated. Transgenic mice and goats were generated with human BChE cDNA under control of the goat ␤-casein promoter. Milk from transgenic animals contained 0.1-5 g/liter of active rBChE. The plasma half-life of PEGylated, goat-derived, purified rBChE in guinea pigs was 7-fold longer than non-PEGylated dimers. The rBChE from transgenic mice was inhibited by nerve agents at a 1:1 molar ratio. Transgenic goats produced active rBChE in milk sufficient for prophylaxis of humans at risk for exposure to OP agents.organophosphorus nerve agent ͉ recombinant protein expression ͉ transgenic production H uman plasma butyrylcholinesterase (huBChE) (EC 3.1.1.8) is a globular, tetrameric serine esterase with a molecular mass of Ϸ340 kDa that is stable in plasma with a half-life of Ϸ12 days (1, 2). Although the physiological function of huBChE is unclear, the enzyme prevents intoxication of animals exposed to organophosphorus (OP) compounds (3, 4). The huBChE enzyme also hydrolyzes many ester-containing drugs, such as cocaine and succinylcholine (5). The toxicity of OP agents is due to irreversible inhibition of acetylcholinesterase and the subsequent continuous stimulation of neurons by acetylcholine (6). Administration of exogenous huBChE, which irreversibly binds OP agents to prevent inactivation of acetylcholinesterase and continuous cholinergic stimulation, is a potential strategy for preventing toxicity from OP agents (4). Although huBChE has been obtained from human plasma by a large scale purification technique, this procedure is severely limited by the volume of human plasma needed (7). It is unlikely that a sufficient amount of enzyme could be purified commercially by this technique. Because of the 1:1 stoichiometry required for protection against exposure to OP agents (8), large quantities of huBChE are needed for effective prophylaxis and treatment of exposure. Compared with other potential enzymatic bioscavengers of OP agents, huBChE has a broad spectrum of activity, a relatively long half-life, and limited, if any, physiological side effects (9). Producing recombinant BChE (rBChE) is an alternative to purification of the enzyme from human plasma. Recombinant huBChE has been expressed in Escherichia coli (10), albeit in a nonfunctional form; mammalian 293T (11); and CHO (12) cells. However, these expression systems cannot economically produce sufficient quantities of rBChE with a residence time similar to native huBChE that would allow development of the enzyme as an agent for prophylaxis against OP poisoning.The production of recombinant proteins by the mammary g...

As a single-element nanomaterial, sulfur nanodots are emerging as a kind of heavy-metal-free nanomaterials which are believed to excel over traditional undesirable compound semiconductor nanocrystals in practical applications. Attaining their potential shall rest on the facile fabrication of high quality samples. Yet, so far the reported fabrication techniques for fluorescent sulfur nanodots have been time-consuming and cost-ineffective. Instead, we employed a strategy of hydrothermal reaction to synthesize sulfur nanodots, which reduces the synthesis time remarkably from generally required 125 h to 4 h. As-synthesized sulfur nanodots (without any post-treatment) manifest good monodispersity and a reasonable photoluminescence quantum yield up to 4.02%. The fission-aggregation mechanism has been proposed to account for the reaction dynamics in the formation of sulfur nanodots. Optical spectroscopic analysis indicates the existence of tail states in the electronic structures of sulfur nanodots, and the photoluminescence properties are governed by both the core and surface states of the sulfur nanodots, which may provide usable hints for manipulating and harnessing the luminescence properties. Besides the insight into both the synthesis and emission mechanism of luminescent sulfur nanodots, our findings pave the way to the bio-related expedite exploitation of these materials.

Carbon dots have attracted tremendous attention because of their intrinsic advantages that open up opportunities to replace traditional fluorescent materials in various application fields. However, until now, the emission mechanism from carbon dots has been controversial, substantially hindering the extensive exploitation of these materials. Here, we explore systematically the essential emission behavior of carbon dots by using polarization anisotropy spectroscopy, electric-field modulation spectroscopy, and time-resolved photoluminescence measurements. We probe the momentum evolution dynamics and evaluate the decay process of the photoexcited hot carriers, which manifest characteristics that are distinct from band edge emission. We provide clear evidence that carbon dot emission originates from radiative recombination of self-trapped excitons, where the mobilization of the carriers is largely impeded due to the existence of a strong local potential field and thus the relaxation of the hot carriers is strongly suppressed. Based on the self-trapped exciton model, all the optical properties of carbon dots inferred from both steady-state and time-resolved optical spectroscopy can be interpreted consistently. Our investigation provides an alternative insight into the emission mechanisms of carbon dots, which may improve our understanding of these novel materials.