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The relativistic charge carriers in monolayer graphene can be manipulated in manners akin to conventional optics. Klein tunneling and Veselago lensing have been previously demonstrated in ballistic graphene pn-junction devices, but collimation and focusing efficiency remains relatively low, preventing realization of advanced quantum devices and controlled quantum interference. Here, we present a graphene microcavity defined by carefully-engineered local strain and electrostatic fields. Electrons are manipulated to form an interference path inside the cavity at zero magnetic field via consecutive Veselago refractions. The observation of unique Veselago interference peaks via transport measurement and their magnetic field dependence agrees with the theoretical expectation. We further utilize Veselago interference to demonstrate localization of uncollimated electrons and thus improvement in collimation efficiency. Our work sheds new light on relativistic single-particle physics and provide a new device concept toward next-generation quantum devices based on manipulation of ballistic electron trajectory., (© 2022. The Author(s).)

The original version of this Article contained errors in Figs. 4 and 6. In Fig. 4, panel a, text labels UAS-FLP and LexAop2>stop>myr::smGdP-HA were shifted upwards during typesetting of the figure, and in Fig. 6, panel h, the number 15 was incorrectly placed on the heat map scale. These have now been corrected in both the PDF and HTML versions of the Article.

Drosophila olfactory local interneurons (LNs) in the antennal lobe are highly diverse and variable. How and when distinct types of LNs emerge, differentiate, and integrate into the olfactory circuit is unknown. Through systematic developmental analyses, we found that LNs are recruited to the adult olfactory circuit in three groups. Group 1 LNs are residual larval LNs. Group 2 are adult-specific LNs that emerge before cognate sensory and projection neurons establish synaptic specificity, and Group 3 LNs emerge after synaptic specificity is established. Group 1 larval LNs are selectively reintegrated into the adult circuit through pruning and re-extension of processes to distinct regions of the antennal lobe, while others die during metamorphosis. Precise temporal control of this pruning and cell death shapes the global organization of the adult antennal lobe. Our findings provide a road map to understand how LNs develop and contribute to constructing the olfactory circuit.

Detecting bacteria in clinical samples without using time-consuming culture processes would allow rapid diagnoses. Such a culture-free detection method requires the capture and analysis of bacteria from a body fluid, which are usually of complicated composition. Here we show that coating Ag-nanoparticle arrays with vancomycin (Van) can provide label-free analysis of bacteria via surface-enhanced Raman spectroscopy (SERS), leading to a ~1,000-fold increase in bacteria capture, without introducing significant spectral interference. Bacteria from human blood can be concentrated onto a microscopic Van-coated area while blood cells are excluded. Furthermore, a Van-coated substrate provides distinctly different SERS spectra of Van-susceptible and Van-resistant Enterococcus, indicating its potential use for drug-resistance tests. Our results represent a critical step towards the creation of SERS-based multifunctional biochips for rapid culture- and label-free detection and drug-resistant testing of microorganisms in clinical samples.