Flexible and wearable pressure sensors are of paramount importance for the development of personalized medicine and electronic skin. However, the preparation of easily disposable pressure sensors is still facing pressing challenges. Herein, we have developed an all paper-based piezoresistive (APBP) pressure sensor through a facile, costeffective, and environmentally friendly method. This pressure sensor was based on a tissue paper coated with silver nanowires (AgNWs) as a sensing material, a nanocellulose paper (NCP) as a bottom substrate for printing electrodes, and NCP as a top encapsulating layer. The APBP pressure sensor showed a high sensitivity of 1.5 kPa −1 in the range of 0.03−30.2 kPa and retained excellent performance in the bending state. Furthermore, the APBP sensor has been mounted on the human skin to monitor physiological signals (such as arterial heart pulse and pronunciation from throat) and successfully applied as a soft electronic skin to respond to the external pressure. Due to the use of the common tissue paper, NCP, AgNWs, and conductive nanosilver ink only, the pressure sensor has advantages of low cost, facile craft, and fast preparation and can be disposed off easily by incineration. We believe that the developed sensor will propel the advancement of easily disposable pressure sensors and green paper-based flexible electronic devices.

2D transition metal chalcogenides have attracted tremendous attention due to their novel properties and potential applications. Although 2D transition metal dichalcogenides are easily fabricated due to their layer-stacked bulk phase, 2D transition metal monochalcogenides are difficult to obtain. Recently, a single atomic layer transition metal monochalcogenide (CuSe) with an intrinsic pattern of nanoscale triangular holes is fabricated on Cu(111). The first-principles calculations show that free-standing monolayer CuSe with holes is not stable, while hole-free CuSe is endowed with the Dirac nodal line fermion (DNLF), protected by mirror reflection symmetry. This very rare DNLF state is evidenced by topologically nontrivial edge states situated inside the spin-orbit coupling gaps. Motivated by the promising properties of hole-free honeycomb CuSe, monolayer CuSe is fabricated on Cu(111) surfaces by molecular beam epitaxy and confirmed success with high resolution scanning tunneling microscopy. The good agreement of angle resolved photoemission spectra with the calculated band structures of CuSe/Cu(111) demonstrates that the sample is monolayer CuSe with a honeycomb lattice. These results suggest that the honeycomb monolayer transition metal monochalcogenide can be a new platform to study 2D DNLFs.

Recently perovskite solar cells (PSCs), as photoelectric conversion devices, exhibit excellent power conversion efficiency (PCE) and low-processing cost, and have become one of the most promising devices to replace conventional silicon-based solar cells and address current pressing energy issues. Among them, the flexible PSCs are especially more widely applicable and may propel the rapid advancements of wearable electronics, causing a significant paradigm shift in consumer electronics. Current flexible PSCs use non-biodegradable petroleum-based polymer substrates, discarding of which will aggravate “white pollution”. Therefore, development of green, biodegradable and low-cost flexible substrates will provide a great alternative to flexible PSCs. Here we have developed transparent nanocellulose paper (NCP) with coating of acrylic resin as substrates to fabricate flexible PSCs, which are biodegradable and easily disposable. The PCE of these NCP-based PSCs reached 4.25%, while the power per weight (the ratio of power to device weight) was as high as 0.56 W g–1. The flexible PSCs also showed good stability, retaining >80% of original efficiency after 50 times of bending. The NCP-based substrates can also be applied to other electronic systems, which may prosper next-generation green flexible electronics.

BackgroundConverging evidence revealed that facial expressions are processed automatically. Recently, there is evidence that facial expressions might elicit the visual mismatch negativity (MMN), expression MMN (EMMN), reflecting that facial expression could be processed under non-attentional condition. In the present study, using a cross modality task we attempted to investigate whether there is a memory-comparison-based EMMN.Methods12 normal adults were instructed to simultaneously listen to a story and pay attention to a non-patterned white circle as a visual target interspersed among face stimuli. In the oddball block, the sad face was the deviant with a probability of 20% and the neutral face was the standard with a probability of 80%; in the control block, the identical sad face was presented with other four kinds of face stimuli with equal probability (20% for each). Electroencephalogram (EEG) was continuously recorded and ERPs (event-related potentials) in response to each kind of face stimuli were obtained. Oddball-EMMN in the oddball block was obtained by subtracting the ERPs elicited by the neutral faces (standard) from those by the sad faces (deviant), while controlled-EMMN was obtained by subtracting the ERPs elicited by the sad faces in the control block from those by the sad faces in the oddball block. Both EMMNs were measured and analyzed by ANOVAs (Analysis of Variance) with repeated measurements. sLORETA (standardized low-resolution brain electromagnetic tomography) was used to investigate the cortical generators of controlled-EMMN.ResultsBoth the oddball-EMMN in deviant-standard comparison and the controlled-EMMN in deviant-control comparison were observed at occipital-temporal regions with right hemisphere predominance. The oddball-EMMN was bigger and earlier than the controlled-EMMN because, besides the memory-based comparison, the former included a difference of refractoriness due to the distinction of presented probability between the deviant and standard face stimuli. The source analysis of controlled-EMMN indicated a current source primarily involved in posterior areas including superior temporal gyrus, postcentral gyrus, inferior parietal lobule as well as the insula.ConclusionsThe valid EMMN properly reflecting the memory-based comparison of facial expressions could be obtained, i.e., the controlled-EMMN.

Phosphine)-and (N-heterocyclic carbene)gold(I) derivatives of naphthalene and pyrene are reported, containing one or two gold atoms per hydrocarbon. The new complexes are prepared by arylation of gold(I) substrates by arylboronic acids or aryl pinacolboronate esters in the presence of cesium carbonate. Isolated yields range from 52% to 98%. The boron precursors themselves derive from the parent hydrocarbon, where boron is installed in an iridium-catalyzed reaction, or from the aromatic bromides, which are borylated with palladium catalysis. Most of the new gold(I) complexes are air-and moisture-stable colorless solids; they are characterized by multinuclear NMR and optical spectroscopy, combustion analysis, and high-resolution mass spectrometry. X-ray diffraction crystal structures are reported for seven. Gold binding red-shifts optical absorption profiles, which are characteristic of the aromatic skeleton. All compounds show triplet-state luminescence, and dual singlet and triplet emission occurs in some instances. Phosphorescence persists for milliseconds at 77 K and for hundreds of microseconds at room temperature. The compounds' photophysical characteristics, along with time-dependent density-functional theory calculations, suggest emission from ππ* states of the aromatic core. Triplet-state geometry optimization finds minimal geometric rearrangement upon one-electron promotion from the (singlet) ground state.

The copper(I)-catalyzed Huisgen [3 þ 2] cycloaddition is a general reaction encompassing wide ranges of organoazide and primarily terminal alkyne reacting partners. Strained internal alkynes can also undergo cycloaddition with azides. We report here that tetrakis(acetonitrile)copper(I) hexafluorophosphate catalyzes the [3 þ 2] cycloaddition of (phosphine)-and (N-heterocyclic carbene)gold(I) alkynyls with benzyl azide. Isolated yields of up to 96% result. The reaction protocol broadly tolerates functionalities on the alkynyl reagent. Gold(I) triazolate products form with complete 1,4-regioselectivity. Some 15 new gold(I) triazolates are reported along with crystal structures of nine. Triazolate complexes bearing polycyclic aromatic substituents show dual singlet-and triplet-state luminescence from excited states localized on the aromatic fragment. Time-resolved emission experiments find long lifetimes consistent with triplet emission parentage. Absorption and emission transitions are analyzed with time-dependent density-functional theory calculations.

We compared early stages of face processing in young and older participants as indexed by ERPs elicited by faces and non-face stimuli presented in upright and inverted orientations. The P1 and N170 components were larger in older than in young participants. However, the early distinction between stimulus categories as reflected by N170 face was similar across groups. Face inversion increased and delayed the N170 peak in the younger group while in older participants inversion delayed the N170 peak but had no effect on amplitude. The N170 amplitude was right-lateralized in the young, but not in the older group. Yet, the difference between the N170 elicited by faces and non-face stimuli was similarly right-lateralized in both groups. These data suggest that detection of faces and their streaming to face-characteristic structural encoding is not altered by age. In contrast, the absence of face-inversion effects on N170 amplitudes in the elderly suggest that face individuation, which is probably the default strategy in younger people, might not be attempted by default in older people, at least when they look at young faces.

A series of phosphane‐ and (N‐heterocyclic carbene)gold(I) complexes were prepared by deprotonation of terminal alkyne precursors and reaction with the corresponding gold(I) chlorides. Some ten new compounds are reported; these are characterized by multinuclear NMR, optical spectroscopy, and elemental analysis. Crystallographic characterization is reported for five complexes. Organogold species bearing conjugated aryl substituents on the alkynyl ligand are luminescent. Density‐functional theory calculations on a model complex suggest that emission and the first several absorption transitions result from excited states dominated by the arylacetylide ligand. Excited‐state geometry optimization finds that the lowest‐energy triplet state bears linear, two‐coordinate gold(I) with a miniscule lengthening of the alkynyl carbon–carbon bond. An unusual triplet excited state having a bent geometry at gold lies at higher energy in arylacetylide complexes. For the model terminal acetylideMe3PAuC≡CH, the calculations find this bent state to be the lowest‐energy triplet.(© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009)