Previous detections of individual astrophysical sources of neutrinos are limited to the Sun and the supernova 1987A, whereas the origins of the diffuse flux of high-energy cosmic neutrinos remain unidentified. On 22 September 2017, we detected a high-energy neutrino, IceCube-170922A, with an energy of ~290 tera-electron volts. Its arrival direction was consistent with the location of a known γ-ray blazar, TXS 0506+056, observed to be in a flaring state. An extensive multiwavelength campaign followed, ranging from radio frequencies to γ-rays. These observations characterize the variability and energetics of the blazar and include the detection of TXS 0506+056 in very-high-energy γ-rays. This observation of a neutrino in spatial coincidence with a γ-ray-emitting blazar during an active phase suggests that blazars may be a source of high-energy neutrinos.

The thylakoid ΔpH-dependent pathway transports folded proteins with twin arginine–containing signal peptides. Identified components of the machinery include cpTatC, Hcf106, and Tha4. The reaction occurs in two steps: precursor binding to the machinery, and transport across the membrane. Here, we show that a cpTatC–Hcf106 complex serves as receptor for specific binding of twin arginine–containing precursors. Antibodies to either Hcf106 or cpTatC, but not Tha4, inhibited precursor binding. Blue native gel electrophoresis and coimmunoprecipitation of digitonin-solubilized thylakoids showed that Hcf106 and cpTatC are members of an ∼700-kD complex that lacks Tha4. Thylakoid-bound precursor proteins were also associated with an ∼700-kD complex and were coimmunoprecipitated with antibodies to cpTatC or Hcf106. Chemical cross-linking revealed that precursors make direct contact with cpTatC and Hcf106 and confirmed that Tha4 is not associated with precursor, cpTatC, or Hcf106 in the membrane. Precursor binding to the cpTatC–Hcf106 complex required both the twin arginine and the hydrophobic core of the signal peptide. Precursors remained bound to the complex when Tha4 was sequestered by antibody, even in the presence of ΔpH. These results indicate that precursor binding to the cpTatC–Hcf106 complex constitutes the recognition event for this pathway and that subsequent participation by Tha4 leads to translocation.

Organic thin-fi lm transistors (OTFTs) have attracted great interest for their potential use in several electronic applications, including active-matrix displays, electronic paper, and chemical sensors. [ 1 ] Among the many semiconducting materials evaluated in the TFT confi guration, pentacene is the best as it shows the highest fi eld-effect mobility ( > 3.0 cm 2 V − 1 s − 1 ). [ 2 , 3 ] On the other hand, new organic semiconductors are being actively investigated to further improve the performance of OTFTs. In fact, superior unconventional organic semiconductors used to produce high-performance OTFTs have been recently reported, including picene (3.2 cm 2 V − 1 s − 1 ), [ 4 ] [ 6 ] and hexamethylene-tetrathiafulvalene (HMTTF, 6.9 cm 2 V − 1 s − 1 . [7] We have also developed several new heteroarenebased organic semiconductors that show high mobility in the TFT confi guration: 2,7-diphenyl[1]benzothieno[3,2-b ]benzothiophene (DPh-BTBT, 2.0 cm 2 V − 1 s − 1 ), [ 8 ] dinaphtho[2,3-b :2 ′ ,3 ′ -f ] thieno[3,2-b ]thiophene (DNTT, 2.9 cm 2 V − 1 s − 1 ), [ 9 ] and alkylatedBTBTs (C n -BTBTs, 3.9 cm 2 V − 1 s − 1 ). [ 10 ] Intrinsically, carrier transport in organic molecular solids is governed by the extent of intermolecular orbital coupling (transfer integrals), where larger orbital coupling can afford higher mobility. [ 11 ] One of the promising approaches to enhance orbital coupling is to use highly π -extended molecules: high-performance OTFTs based on picene, DTTE, or DNTT [ 12 ] that have highly π -extended structure are an example. Another effective approach is to use the self-organizing nature of organic molecules: this is exemplifi ed by DTBDT or C n -BTBTbased OTFTs, in which long alkyl groups can act as the driving force for molecular ordering in the solid state owing to the van der Waals intermolecular interaction between the alkyl groups, or the so-called molecular fastener effect, [ 13 ] that renders the semiconducting core to pack tightly, thereby enhancing carrier mobility. With these molecular design strategies for enhancing TFT performance, we focused on alkylated DNTTs (C n -DNTTs, Scheme 1 ) as new promising molecular semiconductors. In this paper, we report their synthesis, characterization, and OTFT devices that show very high fi eld-effect mobility close to 8.0 cm 2 V − 1 s − 1 .The syntheses of C n -DNTT ( n = 6, 8, 10, 12) were carried out with the same strategy as that for the parent DNTT. Starting from 6-alkyl-2-naphthaldehyde, introduction of methylthio moiety at the 3-position via the selective o -lithiation with lithium N,N,N ′ -trimethylethylenediamide and excess n-BuLi gave 3-methylthio-6-alkyl-2-naphthaldehyde in moderate yields. Low-valent titanium-mediated dimerization of the aldehyde functionality readily gave the olefi ne precursor, which was fi nally converted into C n -DNTTs in moderate to good yields via the idodine-promoted ring closing reaction (Scheme 1 ).[ 9 ] C nDNTTs are stable yellow compounds and their characterization was accomplished by spectroscopic and combustion ...

The thylakoid ΔpH-dependent/Tat pathway is a novel system with the remarkable ability to transport tightly folded precursor proteins using a transmembrane ΔpH as the sole energy source. Three known components of the transport machinery exist in two distinct subcomplexes. A cpTatC–Hcf106 complex serves as precursor receptor and a Tha4 complex is required after precursor recognition. Here we report that Tha4 assembles with cpTatC–Hcf106 during the translocation step. Interactions among components were examined by chemical cross-linking of intact thylakoids followed by immunoprecipitation and immunoblotting. cpTatC and Hcf106 were consistently associated under all conditions tested. In contrast, Tha4 was only associated with cpTatC and Hcf106 in the presence of a functional precursor and the ΔpH. Interestingly, a synthetic signal peptide could replace intact precursor in triggering assembly. The association of all three components was transient and dissipated upon the completion of protein translocation. Such an assembly–disassembly cycle could explain how the ΔpH/Tat system can assemble translocases to accommodate folded proteins of varied size. It also explains in part how the system can exist in the membrane without compromising its ion and proton permeability barrier.

We report the synthesis and characterization of a novel donor-acceptor semiconducting polymer bearing naphthobisthiadiazole (NTz), a doubly benzothiadiazole (BTz)-fused ring, and its applications to organic field-effect transistors and bulk heterojunction solar cells. With NTz's highly π-extended structure and strong electron affinity, the NTz-based polymer (PNTz4T) affords a smaller bandgap and a deeper HOMO level than the BTz-based polymer (PBTz4T). PNTz4T exhibits not only high field-effect mobilities of ~0.56 cm(2)/(V s) but also high photovoltaic properties with power conversion efficiencies of ~6.3%, both of which are significantly high compared to those for PBTz4T. This is most likely due to the more suitable electronic properties and, importantly, the more highly ordered structure of PNTz4T in the thin film than that of PBTz4T, which might originate in the different symmetry between the cores. NTz, with centrosymmetry, can lead to a more linear backbone in the present polymer system than BTz with axisymmetry, which might be favorable for better molecular ordering. These results demonstrate great promise for using NTz as a bulding unit for high-performance semiconducting polymers for both transistors and solar cells.