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For carbon dots, careful purification and electronic structure calculations facilitate learning about the origin of optical properties. 

A major challenge in the “bottom-up” solvothermal synthesis of carbon dots (CDs) is the removal of small-molecule byproducts, noncarbonized polyamides, or other impurities that confound the optical properties. In previously reported benzene diamine-based CDs, the observed fluorescence signal already has been shown to arise from free small molecules, not from nanosized carbonized dots. Here we have unambiguously identified the small-molecule species in the synthesis of CDs starting with several isomers of benzene diamine by directly matching their NMR, mass spectrometry, and optical data with commercially available small organic molecules. By combining dialysis and chromatography, we have sufficiently purified the CD reaction mixtures to measure the CD size by TEM and STM, elemental composition, optical absorption and emission, and single-particle blinking dynamics. The results can be rationalized by electronic structure calculations on small model CDs. Our results conclusively show that the purified benzene diamine-based CDs do not emit red fluorescence, so the quest for full-spectrum fluorescence from isomers of a single precursor molecule remains open. 

Previous research often suggests that people who endorse more essentialist beliefs about social groups are also likely to show increased prejudice towards members of these social groups, and there is even some evidence to suggest that essentialism may lead to prejudice and stereotyping. However, there are several notable exceptions to this pattern in that, for certain social groups (e.g., gay men and lesbians), higher essentialism is actually related to lower prejudice. The current studies further explored the relationship between essentialism and prejudice by examining a novel type of essentialism—transgender essentialism (i.e., essentializing transgender identity), and its relationship to prejudice towards transgender people. Study 1 (N = 248) tested the viability of transgender essentialism as a construct and examined the association between transgender essentialism and transprejudice, while Studies 2a (N = 315), 2b (N = 343), 3a (N = 310), and 3b (N = 204) tested two casual pathways to explain this relationship. The results consistently showed that the more that people endorse transgender essentialist beliefs, the warmer their feelings towards trans people (relative to cis people) were, echoing past research showing a similar relationship between essentialism and prejudice towards sexual minorities. However, the manipulations of both essentialism (Studies 2a and 2b) and prejudice (Studies 3a and 3b) were largely unsuccessful at changing the desired construct, meaning we were unable to provide direct causal tests. The one exception was a successful manipulation of the universality of trans experiences, but even here this resulted in no change in prejudice. The primary contribution of this work is in robustly demonstrating that greater transgender essentialism is associated with transprejudice.