Compounds consisting only of the element nitrogen (polynitrogens or nitrogen allotropes) are considered promising clean energy-storage materials owing to their immense energy content that is much higher than hydrogen, ammonia or hydrazine, which are in common use, and because they release only harmless nitrogen on decomposition1. However, their extreme instability poses a substantial synthetic challenge and no neutral molecular nitrogen allotrope beyond N2 has been isolated2,3. Here we present the room-temperature preparation of molecular N6 (hexanitrogen) through the gas-phase reaction of chlorine or bromine with silver azide, followed by trapping in argon matrices at 10 K. We also prepared neat N6 as a film at liquid nitrogen temperature (77 K), further indicating its stability. Infrared and ultraviolet-visible (UV-Vis) spectroscopy, 15N-isotope labelling and ab initio computations firmly support our findings. The preparation of a metastable molecular nitrogen allotrope beyond N2 contributes to our fundamental scientific knowledge and possibly opens new opportunities for future energy-storage concepts.

Conservation of damaged oil paintings requires manual inpainting of losses1,2, leading to months-long treatments of considerable expense; 70% of paintings in institutional collections are locked away from public view, in part because of treatment cost3,4. Recent advancements in digital image reconstruction have helped to envision treatment results, although without any direct means of achieving them5-8. Here I describe the physically applied digital restoration of a painting, a highly damaged oil-on-panel attributed to the Master of the Prado Adoration from the late fifteenth century. In parallel, 5,612 losses spanning 66,205 mm2 and 57,314 colours were infilled with a reversible laminate mask comprising a colour-accurate bilayer of printed pigments on polymeric films. To ensure the effectiveness of the restoration, ethical principles in painting conservation were implemented quantitatively for digital mask construction, a critically important foundation lacking in the current digital restoration literature. The infill process took 3.5 h, an estimated 66 times faster than conventional inpainting, and the result closely matched the simulation. This approach grants greatly increased foresight and flexibility to conservators, enabling the restoration of countless damaged paintings deemed unworthy of high conservation budgets.

Silicon has enabled advancements in semiconductor technology through miniaturization, but scaling challenges necessitate the exploration of new materials1. Two-dimensional (2D) materials, with their atomic thickness and high carrier mobility, offer a promising alternative2-5. Although significant progress has been made in wafer-scale growth6-8, high-performance field-effect transistors9-20 and circuits based on 2D materials21-23, achieving complementary metal-oxide-semiconductor (CMOS) integration remains a challenge. Here, we present a 2D one instruction set computer based on CMOS technology, leveraging the heterogeneous integration of large-area n-type MoS2 and p-type WSe2 field-effect transistors. By scaling the channel length, incorporating a high-κ gate dielectric and optimizing material growth and device postprocessing, we tailored the threshold voltages for both n- and p-type 2D field-effect transistors, achieving high drive currents and reduced subthreshold leakage. This enabled circuit operation below 3 V with an operating frequency of up to 25 kHz, which was constrained by parasitic capacitances, along with ultra-low power consumption in the picowatt range and a switching energy as low as approximately 100 pJ. Finally, we projected the performance of the one instruction set computer and benchmarked it against state-of-the-art silicon technology using an industry-standard SPICE-compatible BSIM-BULK model. This model was calibrated with experimental data that incorporate device-to-device variations. Although further advances are needed, this work marks a significant milestone in the application of 2D materials to microelectronics.