The conductance of metallic graphene nanoribbons (GNRs) with single defects and weak disorder at their edges is investigated in a tight-binding model. We find that a single edge defect will induce quasi-localized states and consequently cause zero-conductance dips. The center energies and breadths of such dips are strongly dependent on the geometry of GNRs. Armchair GNRs are much more sensitive to a vacancy than zigzag GNRs, but are less sensitive to a weak scatter. More importantly, we find that with a weak disorder, zigzag GNRs will change from metallic to semiconducting due to Anderson localization. But a weak disorder only slightly affects the conductance of armchair GNRs. The influence of edge defects on the conductance will decrease when the widths of GNRs increase.Comment: 8 pages and 11 figure

Mutations in gene regulatory elements have been associated with a wide range of complex neuropsychiatric disorders. However, due to their cell-type specificity and difficulties in characterizing their regulatory targets, the ability to identify causal genetic variants has remained limited. To address these constraints, we perform integrative analysis of chromatin interactions using promoter capture Hi-C (pcHi-C), open chromatin regions using ATAC-seq, and transcriptomes using RNA-seq in four functionally distinct neural cell types: iPSC-induced excitatory neurons and lower motor neurons, iPSC-derived hippocampal dentate gyrus (DG)-like neurons, and primary astrocytes. We identify hundreds of thousands of long-range cis interactions between promoters and distal promoter-interacting regions (PIRs), enabling us to link regulatory elements to their target genes and reveal putative processes that are dysregulated in disease. Finally, we validate several PIRs using CRISPR techniques in human excitatory neurons, demonstrating that CDK5RAP3 , STRAP , and DRD2 are transcriptionally regulated by physically linked enhancers.

Abstract. We describe here characterization of a new stateof-the-art smog chamber facility for studying atmospheric gas-phase and aerosol chemistry. The chamber consists of a 30 m 3 fluorinated ethylene propylene (FEP) Teflon film reactor housed in a temperature-controlled enclosure equipped with black lamps as the light source. Temperature can be set in the range from −10 to 40 • C at accuracy of ±1 • C as measured by eight temperature sensors inside the enclosure and one just inside the reactor. Matrix air can be purified with non-methane hydrocarbons (NMHCs) < 0.5 ppb, NO x /O 3 /carbonyls < 1 ppb and particles < 1 cm −3 . The photolysis rate of NO 2 is adjustable between 0 and 0.49 min −1 . At 298 K under dry conditions, the average wall loss rates of NO, NO 2 and O 3 were measured to be 1.41 × 10 −4 min −1 , 1.39 × 10 −4 min −1 and 1.31 × 10 −4 min −1 , respectively, and the particle number wall loss rate was measured to be 0.17 h −1 . Auxiliary mechanisms of this chamber are determined and included in the Master Chemical Mechanism to evaluate and model propene-NO x -air irradiation experiments. The results indicate that this new smog chamber can provide high-quality data for mechanism evaluation. Results of α-pinene dark ozonolysis experiments revealed secondary organic aerosol (SOA) yields comparable to those from other chamber studies, and the two-product model gives a good fit for the yield data obtained in this work. Characterization experiments demonstrate that our Guangzhou Institute of Geochemistry, Chinese Academy Sciences (GIG-CAS), smog chamber facility can be used to provide valuable data for gas-phase chemistry and secondary aerosol formation.

CRISPR-Cas9 has been demonstrated to delete genes in postmitotic neurons. Compared to the establishment of proliferative cell lines or animal strains, it is more challenging to acquire a highly homogeneous consequence of gene editing in a stable neural network. Here we show that dCas9-based CRISPR interference (CRISPRi) can efficiently silence genes in neurons. Using a pseudotarget fishing strategy, we demonstrate that CRISPRi shows superior targeting specificity without detectable off-target activity. Furthermore, CRISPRi can achieve multiplex inactivation of genes fundamental for neurotransmitter release with high efficiency. By developing conditional CRISPRi tools targeting synaptotagmin I (Syt1), we modified the excitatory to inhibitory balance in the dentate gyrus of the mouse hippocampus and found that the dentate gyrus has distinct regulatory roles in learning and affective processes in mice. We therefore recommend CRISPRi as a useful tool for more rapid investigation of gene function in the mammalian brain.

Abstract. In China, a rapid increase in passenger vehicles has led to the growing concern of vehicle exhaust as an important source of anthropogenic secondary organic aerosol (SOA) in megacities hard hit by haze. In this study, the SOA formation of emissions from two idling light-duty gasoline vehicles (LDGVs) (Euro 1 and Euro 4) operated in China was investigated in a 30 m3 smog chamber. Five photo-oxidation experiments were carried out at 25 °C with relative humidity at around 50 %. After aging at an OH exposure of 5 × 106 molecules cm−3 h, the formed SOA was 12–259 times as high as primary organic aerosol (POA). The SOA production factors (PF) were 0.001–0.044 g kg−1 fuel, comparable with those from the previous studies at comparable OH exposure. This quite lower OH exposure than that in typical atmospheric conditions might however lead to the underestimation of the SOA formation potential from LDGVs. Effective SOA yields in this study were well fit by a one-product gas-particle partitioning model but quite lower than those of a previous study investigating SOA formation from three idling passenger vehicles (Euro 2–4). Traditional single-ring aromatic precursors and naphthalene could explain 51–90 % of the formed SOA. Unspeciated species such as branched and cyclic alkanes might be the possible precursors for the unexplained SOA. A high-resolution time-of-flight aerosol mass spectrometer was used to characterize the chemical composition of SOA. The relationship between f43 (ratio of m/z 43, mostly C2H3O+, to the total signal in mass spectrum) and f44 (mostly CO2+) of the gasoline vehicle exhaust SOA is similar to the ambient semi-volatile oxygenated organic aerosol (SV-OOA). We plot the O : C and H : C molar ratios of SOA in a Van Krevelen diagram. The slopes of ΔH : C / ΔO : C ranged from −0.59 to −0.36, suggesting that the oxidation chemistry in these experiments was a combination of carboxylic acid and alcohol/peroxide formation.

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Developing functional hybrids of globular proteins and synthetic polymers into multipurpose tough hydrogels remains challenging. Here, we propose a new strategy combining double-network and protein misfolding concepts to create diverse protein–polymer double-network (DN) hydrogels with both high bulk and interfacial toughness. The method integrates an intrinsic heat-induced protein denaturation/aggregation feature and a double-network concept, which produces different bovine serum albumin (BSA)-based DN hydrogels with hybrid physical–chemical cross-linking or fully physical cross-linking to achieve a high modulus of 252–1199 kPa, high strength of 0.24–0.48 MPa, high fracture energy of 3.56–16.88 MJ/m3, high extensibility of 7.7–79.9 mm/mm, fast self-recovery (stiffness/toughness recovery of 94/80% after heat treatment at 80 °C for 30 min), and strong surface adhesion to various nonporous solid surfaces (interfacial toughness of 1176–2827 J/m2). Such tough and adhesive protein–polymer hydrogels have great potential for different applications, such as artificial soft tissues, flexible electronics, and wearable devices.

Pt/poly(3-hexylthiophene-2,5-diyl)/polyethylene oxide + Li+/Pt hetero junctions were fabricated, and their pulse responses were studied. The direct current characteristics were not symmetric in the sweeping range of ±2 V. Negative differential resistance appeared in the input range of 0 to 2 V because of de-doping (or reduction) in the side with the semiconductor layer. The device responded stably to a train of pulses with a fixed frequency. The inverse current after a pulse was related to the back-migrated ions. Importantly, the weight calculated based on the inverse current strength, was depressed during low-frequency stimulations but was potentiated during high-frequency stimulations when pulses were positive. Therefore, frequency selectivity was first observed in a semiconducting polymer/electrolyte hetero junction. Detailed analysis of the pulse response showed that the input frequency could modulate the timing of ion doping, de-doping, and re-doping at the semiconducting polymer/electrolyte interface, which then resulted in the frequency selectivity. Our study suggests that the simple redox process in semiconducting polymers can be modulated and used in signal handling or the simulation of bio-learning.