Crystal structure analyses for biological macromolecules without known structural relatives entail solving the crystallographic phase problem. Typical de novo phase evaluations depend on incorporating heavier atoms than those found natively; most commonly, multi- or single-wavelength anomalous diffraction (MAD or SAD) experiments exploit selenomethionyl proteins. Here we realize routine structure determination using intrinsic anomalous scattering from native macromolecules. We devised robust procedures for enhancing signal-to-noise in the slight anomalous scattering from generic native structures by combining data measured from multiple crystals at lower-than-usual x-ray energy. Using this multi-crystal SAD method (5–13 equivalent crystals), we determined structures at modest resolution (2.8Å-2.3Å) for native proteins varying in size (127–1148 unique residues) and number of sulfur sites (3–28). With no requirement for heavy-atom incorporation, such experiments provide an attractive alternative to selenomethionyl SAD experiments.

The role of band bending on the efficiency of charge transfer across the TiO 2 (110) single crystal surface has been measured in ultrahigh vacuum, in the absence of a wide range of surface site inhomogeneities, surface impurities and solvent effects, and particle size effects. The adsorption of the Cl 2 (electron acceptor) molecule and the O 2 (electron acceptor) molecule have been found to enhance hole transport from TiO 2 to 18 O 2 molecules adsorbed on oxygen vacancy sites, increasing the rate of electron stimulated desorption (ESD) of 18 O 2 . This confirms that O 2 -ESD is hole mediated. Conversely, adsorption of CH 3 OH, a donor molecule, reduces the transfer rate for holes to the adsorbed O 2 , reducing its rate of ESD to near zero. The maximum effect of donor and acceptor molecules occurs near 1 monolayer coverage.

Elastic, piezoelectric, and dielectric properties of Ba(Zr0.2Ti0.8)O3-50(Ba0.7Ca0.3)TiO3 Pb-free ceramic at the morphotropic phase boundary

Self-powered wearable electronics require thermoelectric materials simultaneously with a high dimensionless figure of merit (zT) and good flexibility to convert the heat discharged by the human body into electricity. Ag2(S,Se)-based semiconducting materials can well satisfy these requirements, and thus, they are attracting great attention in thermoelectric society recently. Ag2(S,Se) crystalizes in an orthorhombic structure or monoclinic structure, depending on the detailed S/Se atomic ratio, but the relationship between its crystalline structure and mechanical/thermoelectric performance is still unclear to date. In this study, a series of Ag2Se1‐xSx (x=0, 0.1, 0.2, 0.3, 0.4, and 0.45) samples were prepared and their mechanical and thermoelectric performance dependence on the crystalline structure was systematically investigated. x=0.3 in the Ag2Se1‐xSx system was found to be the transition boundary between orthorhombic and monoclinic structures. Mechanical property measurement shows that the orthorhombic Ag2Se1‐xSx samples are brittle while the monoclinic Ag2Se1‐xSx samples are ductile and flexible. In addition, the orthorhombic Ag2Se1‐xSx samples show better electrical transport performance and higher zT than the monoclinic samples under a comparable carrier concentration, most likely due to their weaker electron-phonon interactions. This study sheds light on the further development of flexible inorganic TE materials.

Thermally-activated delayed fluorescence (TADF) emitters-just like phosphorescent ones-can in principle allow for 100% internal quantum efficiency of organic light-emitting diodes (OLEDs), because the initially formed electron-hole pairs in the non-emissive triplet state can be efficiently converted into emissive singlets by reverse intersystem crossing. However, as compared to phosphorescent emitter complexes with their bulky-often close to spherical-molecular structures, TADF emitters offer the advantage to align them such that their optical transition dipole moments (TDMs) lie preferentially in the film plane. In this report, we address the question which factors control the orientation of TADF emitters. Specifically, we discuss how guest-host interactions may be used to influence this parameter and propose an interplay of different factors being responsible. We infer that emitter orientation is mainly governed by the molecular shape of the TADF molecule itself and by the physical properties of the host-foremost, its glass transition temperature T g and its tendency for alignment being expressed, e.g., as birefringence or the formation of a giant surface potential of the host. Electrostatic dipole-dipole interactions between host and emitter are not found to play an important role.

Multiwavelength anomalous diffraction (MAD) and singlewavelength anomalous diffraction (SAD) are the two most commonly used methods for de novo determination of macromolecular structures. Both methods rely on the accurate extraction of anomalous signals; however, because of factors such as poor intrinsic order, radiation damage, inadequate anomalous scatterers, poor diffraction quality and other noisecausing factors, the anomalous signal from a single crystal is not always good enough for structure solution. In this study, procedures for extracting more accurate anomalous signals by merging data from multiple crystals are devised and tested. SAD phasing tests were made with a relatively large (1456 ordered residues) poorly diffracting (d min = 3.5 Å ) selenomethionyl protein (20 Se). It is quantified that the anomalous signal, success in substructure determination and accuracy of phases and electron-density maps all improve with an increase in the number of crystals used in merging. Structure solutions are possible when no single crystal can support structural analysis. It is proposed that such multi-crystal strategies may be broadly useful when only weak anomalous signals are available.

employing a purely organic TADF emitter, 4CzIPN. [3] TADF molecules have an energy gap between the S 1 and T 1 states, ΔE ST , sufficiently small to allow the triplet excitons to convert into singlet excitons through reverse intersystem crossing (RISC), making possible their radiative decay from the singlet excited state, evidenced by a delayed fluorescence. To minimize ΔE ST and enhance k RISC , the overlap between the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) of the molecule must likewise be small, which is achievable in compounds containing electron-donating and electron-accepting moieties that are poorly electronically coupled giving the excited state an intra-molecular charge-transfer (CT) character. [4] The most common emitter designs rely on a large twist angle between the donor and acceptor coupled with the incorporation of aromatic spacer bridging moieties. [5] The external quantum efficiency (EQE) of the OLED is a function not only of the IQE but also of the light out-coupling efficiency. As the stack of an OLED device is composed of several different layers of materials included between two electrodes, total internal reflection at the interface between two media, and coupling to surface plasmon polaritons (SPP) at the interface with Organic thermally activated delayed fluorescent (TADF) materials can harvest 100% of the electrically generated excitons as a result of their small singlet-triplet energy difference. However, maximizing the external quantum efficiency (EQE) of a device also requires enhancing the light out-coupling efficiency. This work presents a new acceptor-donor-acceptor (ADA) emitter employing an indolocarbazole donor and diphenyltriazine acceptors that show nearly-completely horizontal orientation regardless of the host matrix, leading to a sky-blue organic light-emitting diode (λ EL = 483 nm, CIE coordinates of 0.17, 0.32) with EQE MAX of 22.1%, a maximum luminance of 7800 cd m −2 , and blue emission.

We developed a new and highly sensitive method for miRNA detection and intracellular imaging based on novel nucleic acid molecular aggregates self-assembled on graphene oxide nanoplates.