We show here that the carrier mobility in the novel sp-sp(2) hybridization planar 6,6,12-graphyne sheet should be even larger than that in the graphene sheet. Both graphyne and graphene exhibit a Dirac cone structure near the Fermi surface. However, due to the sp-sp(2) hybridization forming the triple bonds in graphyne, the electron-phonon scattering is reduced compared with that of graphene. The carrier mobility is calculated at the first-principles level by using the Boltzmann transport equation coupled with the deformation potential theory. The intrinsic mobility of the 6,6,12-graphyne is 4.29 × 10(5) cm(2) V(-1) s(-1) for holes and 5.41 × 10(5) cm(2) V(-1) s(-1) for electrons at room temperature, which is found to be larger than that of graphene (∼ 3 × 10(5) cm(2) V(-1) s(-1)).

The signaling network of innate immunity in Drosophila is constructed by multiple evolutionarily conserved pathways, including the Toll-or Imd-regulated NF-κB and JNK pathways. The p38 MAPK pathway is evolutionarily conserved in stress responses, but its role in Drosophila host defense is not fully understood. Here we show that the p38 pathway also participates in Drosophila host defense. In comparison with wild-type flies, the sensitivity to microbial infection was slightly higher in the p38a mutant, significantly higher in the p38b mutant, but unchanged in the p38c mutant. The p38b; p38a double-mutant flies were hypersensitive to septic injury. The immunodeficiency of p38b;p38a mutant flies was also demonstrated by hindgut melanization and larvae stage lethality that were induced by microbes naturally presented in fly food. A canonical MAP3K-MKK cascade was found to mediate p38 activation in response to infection in flies. However, neither Toll nor Imd was required for microbe-induced p38 activation. We found that p38-activated heat-shock factor and suppressed JNK collectively contributed to host defense against infection. Together, our data demonstrate that the p38 pathway-mediated stress response contribute to Drosophila host defense against microbial infection.

Control of doping is crucial for enhancing the thermoelectric efficiency of a material. However, doping of organic semiconductors often reduces their mobilities, making it challenging to improve the thermoelectric performance. Targeting on this problem, we propose a simple model to quantitatively obtain the optimal doping level and the peak value of thermoelectric figure of merit (zT) from the intrinsic carrier mobility, the lattice thermal conductivity, and the effective density of states. The model reveals that high intrinsic mobility and low lattice thermal conductivity give rise to a low optimal doping level and a high maximum zT. To demonstrate how the model works, we investigate, from first-principles calculations, the thermoelectric properties of a novel class of excellent hole transport organic materials, 2,7-dialkyl[1]benzothieno[3,2-b][1]benzothiophene derivatives (C n -BTBTs). The first-principles calculations show that BTBTs exhibit high mobilities, extremely low thermal conductivities (∼0.2 W m–1 K–1), and large Seebeck coefficients (∼0.3 mV K–1), making them ideal candidates for thermoelectric applications. Moreover, the maximum zT predicted from the simple model agrees with that observed from the first-principles calculations. This study has provided new insights to guide the search for organic thermoelectric materials and their optimization.

A photoelectronic switch of a multilevel memory device has been achieved using a meta-conjugated donor-bridge-acceptor (DBA) molecule. Such a DBA optoelectronic molecule responds to both the optical and electrical stimuli. The device exhibits good electrical bistable switching behaviors under dark, with a large ON/OFF ratio more than 10(6). In cooperation with the UV light, photoelectronic ternary states are addressable in a bistable switching system. On the basis of the CV measurement, charge carriers transport modeling, quantum chemical calculation, and absorption spectra analysis, the mechanism of the DBA memory is suggested to be attributed to the substep charge transfer transition process. The capability of tailoring photoelectrical properties is a very promising strategy to explore the multilevel storage, and it will give a new opportunity for designing multifunctional devices.

Thermoelectric energy converters can directly convert heat to electricity using semiconducting materials via the Seebeck effect and electricity to heat via the Peltier effect. Their efficiency depends on the dimensionless thermoelectric figure of merit of the material, which is defined as zT = S(2)σT/κ with S, σ, κ, and T being the Seebeck coefficient, electrical conductivity, thermal conductivity, and absolute temperature respectively. Organic materials for thermoelectric applications have attracted great attention. In this review, we present our recent progress made in developing theories and computational schemes to predict the thermoelectric figure of merit at the first-principles level. The methods have been applied to model thermoelectric transport in closely-packed molecular crystals and one-dimensional conducting polymer chains. The physical insight gained in these studies will help in the design of efficient organic thermoelectric materials.

Esophageal cancer (EC) is one of the most common gastrointestinal cancers, which leads to the sixth ranking of cancer-related death. Long non-coding RNAs (lncRNAs) play pivotal roles in many biological processes. lncRNA human urothelial carcinoma associated 1 (UCA1) is significantly upregulated and functions as an important oncogene in many types of human cancers. However, the role of UCA1 in EC and its underlying mechanism remains unclear. In the present study, we demonstrated that UCA1 was significantly upregulated in EC tissues and associated with poor prognosis. Overexpression of UCA1 promoted the proliferation of EC cells, while silence of UCA1 inhibited EC cells growth. Furthermore, we found that Sox4 was a direct target gene of UCA1. UCA1 regulated Sox4 expression through functioning as a competing endogenous RNA (ceRNA). UCA1 directly interacted with miR-204 and decreased the binding of miR-204 to Sox4 3'UTR, which suppressed the degradation of Sox4 mRNA by miR-204. This study provides the first evidence that UCA1 promotes cell proliferation through Sox4 in EC, suggesting that UCA1 and Sox4 may be potential therapeutic targets for EC.

We propose a combined computational scheme to predict the thermoelectric properties of organic semiconductors, taking α-form phthalocyanine crystals H2Pc, CuPc, NiPc, and TiOPc as examples. This completely parameter-free approach combines first-principles band structure calculations, Boltzmann transport theory, deformation potential theory for electron-phonon coupling, and nonequilibrium molecular dynamics for heat transport. We abandon the constant relaxation time approximation commonly practiced in the literature. Instead, we calculate it from first principles with the deformation potential approximation. The obtained Seebeck coefficients are in good agreement with experimental results, validating our treatment for relaxation time. From the calculated thermoelectric figure of merit (ZT) value, we show that phthalocyanine crystals could be excellent thermoelectric materials when n-doped, with the highest ZT value of 2.5 in NiPc at a doping level of -1.5 × 10(20) cm(-3).

Recently, polymer solar cells (PSCs) exhibit promising potential in the world's renewable energy strategy due to their unique advantages such as low cost, light weight, and large-area fabrication on flexible substrates and have attracted much attention. 1À7 Through the creation of novel donor and acceptor materials and innovation of device fabrication technology, PSCs based on regioregular poly(3-hexylthiophene) (P3HT) have reached power conversion efficiencies (PCEs) over 6%, 8À10 and PCEs of PSCs based on alternating copolymers have been over 7%. 11À16 To further improve the PCE of PSCs, on one hand, electron donors and electron acceptors should have broad absorption, high mobility, and suitable energy levels; on the other hand, a better nanostructural ordering of donor and acceptor blends also facilitates charge generation and transport.Thiazole is a widely used electron-accepting heterocycle due to electron-withdrawing nitrogen of imine (CdN). Small molecules and polymers based on bithiazole were used as semiconductors in organic field-effect transistors (OFETs) and exhibited high electron or hole mobility. 17À20 Recently, conjugated copolymer-based bithiazoles have been used in PSCs as donors, and PCEs up to 3.82% were achieved in combination with PC 71 BM acceptor. 21À31 Most research work focused on main chain engineering of the bithiazole polymers, while there have been no reports on side chain engineering of the bithiazole polymers.Long conjugation length, planar molecular geometry, and rigid structure in π-conjugated polymers often leads to poor solubility or even insoluble in common solvents. For solution processing, the use of long alkyl or alkoxy side chains has been a common approach to improve the solubility of conjugated polymers. However, the side chain nature and position not only affect the molecular weight, solubility, and geometry of the polymers but also affect the absorption, energy levels, and charge transport properties. 32À42 Furthermore, the side chain affects morphology of resulting blends of polymer donors and fullerene acceptors, which has been regarded as a critical factor in determining the PCEs of the photovoltaic devices, and finally affects the photovoltaic performance of devices. 12,43À51Here we demonstrate synthesis and characterization of four structural related copolymers of bithiazole and benzodithiophene with the same backbone but different side chain pattern (P1ÀP4, Figure 1). In particular, we probe into impact of the shape and position of side chains on solubility, absorption, energy levels, and charge transport properties of the polymers as well as on morphology and photovoltaic properties of the donor/acceptor blends. Tiny difference in the side chains of ABSTRACT: Four new copolymers P1ÀP4 containing the same backbone of bithiazole acceptor unit and benzodithiophene donor unit but different side chain pattern were synthesized by Pd-catalyzed Stille coupling. The effect of the side chains on backbone conformation, solubility, absorption spectra, energy levels, charg...