Search

The emergence of superconductivity in doped insulators such as cuprates and pnictides coincides with their doping-driven insulator-metal transitions. Above the critical doping threshold, a metallic state sets in at high temperatures, while superconductivity sets in at low temperatures. An unanswered question is whether the formation of Cooper pairsin a well-established metal will inevitably transform the host material into a superconductor, as manifested by a resistance drop. Here, this question is addressed by investigating the electrical transport in nanoscale rings (full loops) and half loops manufactured from heavily boron-doped diamond. It is shown that in contrast to the diamond half-loops (DHLs) exhibiting a metal-superconductor transition, the diamond nanorings (DNRs) demonstrate a sharp resistance increase up to 430% and a giant negative "magnetoresistance" below the superconducting transition temperature of the starting material. The finding of the unconventional giant negative "magnetoresistance", as distinct from existing categories of magnetoresistance, that is, the conventional giant magnetoresistance in magnetic multilayers, the colossal magnetoresistance in perovskites, and the geometric magnetoresistance in semiconductor-metal hybrids, reveals the transformation of the DNRs from metals to bosonic semiconductors upon the formation of Cooper pairs. DNRs like these could be used to manipulate Cooper pairs in superconducting quantum devices. ispartof: ADVANCED MATERIALS vol:35 issue:22 ispartof: location:Germany status: Published online

ispartof: POLYMERS FOR ADVANCED TECHNOLOGIES vol:32 issue:4 pages:1507-1517 status: published

Research on optically resonant dielectric nanostructures has accelerated the development of photonic applications, driven by their ability to strongly confine light on the nanoscale. However, since dielectric resonators are typically operated below their bandgap to minimize optical losses, the usage of dielectric nanoantenna concepts for absorption enhancement has largely remained unexplored. In this work, we realize engineered nanoantennas composed of photocatalytic dielectrics and demonstrate their increased light harvesting capabilities in otherwise weakly absorptive spectral regions. In particular, we employ anapole excitations, which are known for their strong light confinement, in nanodisks of oxygen-vacancy-rich TiO2-x, a prominent photocatalyst that provides a powerful platform for exploring concepts in absorption enhancement in tunable nanostructures. We show that by varying the nanodisk geometry, we can shift the anapole wavelength into resonance with optical transitions associated with the sub-bandgap oxygen vacancy (VO) states and thereby increase visible light absorption. The arising photocatalytic effect is monitored on the single particle level using the well-established photocatalytic silver reduction reaction on TiO2. With the freedom of changing the optical properties of TiO2 through tuning the abundance of VO-states we discuss the interplay between cavity damping and the anapole-assisted field confinement for absorption enhancement. This concept is general and can be extended to other catalytic materials with higher refractive indices.

The origin of the eukaryotic cell is a major open question in biology. Asgard archaea are the closest known prokaryotic relatives of eukaryotes, and their genomes encode various eukaryotic signature proteins, indicating some elements of cellular complexity prior to the emergence of the first eukaryotic cell. Yet, microscopic evidence to demonstrate the cellular structure of uncultivated Asgard archaea in the environment is thus far lacking. We used primer-free sequencing to retrieve 715 almost full-length Loki- and Heimdallarchaeota 16S rRNA sequences and designed novel oligonucleotide probes to visualize their cells in marine sediments (Aarhus Bay, Denmark) using catalyzed reporter deposition-fluorescence in situ hybridization (CARD-FISH). Super-resolution microscopy revealed 1–2 µm large, coccoid cells, sometimes occurring as aggregates. Remarkably, the DNA staining was spatially separated from ribosome-originated FISH signals by 50–280 nm. This suggests that the genomic material is condensed and spatially distinct in a particular location and could indicate compartmentalization or membrane invagination in Asgard archaeal cells.

Cdc42 GTPase rules cell polarity and growth in fission yeast. It is negatively and positively regulated by GTPase-activating proteins (GAPs) and guanine nucleotide exchange factors (GEFs), respectively. Active Cdc42-GTP localizes to the poles, where it associates with numerous proteins constituting the polarity module. However, little is known about its downregulation. We describe here that oxidative stress causes Sty1-kinase-dependent Cdc42 inactivation at cell poles. Both the amount of active Cdc42 at tips and cell length inversely correlate with Sty1 activity, explaining the elongated morphology of Δsty1 cells. We have created stress-blinded cell poles either by eliminating two Cdc42 GAPs or through the constitutive tethering of Gef1 to cell tips, and we biochemically demonstrate that the GAPs Rga3/6 and the GEF Gef1 are direct substrates of Sty1. We propose that phosphorylation of Rga3/6 and Gef1 mediates the Sty1-dependent inhibition of Cdc42 at cell tips, halting polarized growth during stress adaptation., This work is supported by the Ministerio de Ciencia, Innovación y Universidades (Spain), PLAN E, and FEDER (grant PGC2018-093920-B-I00 to E.H., PGC2018-097248-B-I00 to J.A., and PGC2018-098924-B-100 to P.P.). The Oxidative Stress and Cell Cycle group is also supported by Generalitat de Catalunya (Spain) (2017-SGR-539) and Unidad de Excelencia María de Maeztu, funded by the AEI (Spain) (grant CEX2018-000792-M). P.P. is also supported by Junta de Castilla y León (Escalera de la Excelencia) (grant CLU-2017-03). C.S.-C. was recipient of a María de Maeztu predoctoral fellowship from the Ministerio de Economía y Competitividad (Spain), With funding from the Spanish government through the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2018-000792-M).

Tailoring optical properties in photocatalysts by nanostructuring them can help increase solar light harvesting efficiencies in a wide range of materials. Whereas plasmon resonances are widely employed in metallic catalysts for this purpose, latest advances of nonradiative, dielectric nanophotonics also enable light confinement and enhanced visible light absorption in semiconductors. Here, a design procedure for large-scale nanofabrication of semiconductor photoelectrodes using imprint lithography is developed. Anapole excitations and metasurface lattice resonances are combined to enhance the absorption of the model material, amorphous gallium phosphide (a-GaP), over the visible spectrum. It is shown that cost-effective, high sample throughput is achieved while retaining the precise signature of the engineered photonic states. Photoelectrochemical measurements under hydrogen evolution reaction conditions and sunlight illumination reveal the contributions of the respective resonances and demonstrate an overall photocurrent enhancement of 5.7, compared to a planar film. These results are supported by optical and numerical analysis of single nanodisks and of the upscaled metasurface.https://onlinelibrary.wiley.com/doi/10.1002/aenm.202102877

Optical resonances arising from quasi-bound states in the continuum (QBICs) have been recently identified in nanostructured dielectrics, showing ultrahigh quality factors accompanied by very large electromagnetic field enhancements. In this work, we design a periodic array of gallium phosphide (GaP) elliptical cylinders supporting, concurrently, three spectrally separated QBIC resonances with in-plane magnetic dipole, out-of-plane magnetic dipole, and electric quadrupole characters. We numerically explore this system for second-harmonic generation and degenerate four-wave mixing, demonstrating giant per unit cell conversion efficiencies of up to ∼ 2 W−1 and ∼ 60 W−2, respectively, when considering realistic introduced asymmetries in the metasurface, compatible with current fabrication limitations. We find that this configuration outperforms by up to more than four orders of magnitude the response of low-Q Mie or anapole resonances in individual GaP nanoantennas with engineered nonlinear mode-matching conditions. Benefiting from the straight-oriented electric field of one of the examined high-Q resonances, we further propose a novel nanocavity design for enhanced spectroscopies by slotting the meta-atoms of the periodic array. We discover that the optical cavity sustains high-intensity fields homogeneously distributed inside the slot, delivering its best performance when the elliptical cylinders are cut from end to end forming a gap, which represents a convenient model for experimental investigations. When placing an electric point dipole inside the added aperture, we find that the metasurface offers ultrahigh radiative enhancements, exceeding the previously reported slotted dielectric nanodisk at the anapole excitation by more than two orders of magnitude.

Tailorable synthesis of III-V semiconductor heterostructures in nanowires (NWs) enables new approaches with respect to designing photonic and electronic devices at the nanoscale. We present a comprehensive study of highly controllable self-catalyzed growth of gallium phosphide (GaP) NWs on template-free silicon (111) substrates by molecular beam epitaxy. We report the approach to form the silicon oxide layer, which reproducibly provides a high yield of vertical GaP NWs and control over the NW surface density without a pre-patterned growth mask. Above that, we present the strategy for controlling both GaP NW length and diameter independently in single- or two-staged self-catalyzed growth. The proposed approach can be extended to other III-V NWs.

Gallium phosphide (GaP) is an indirect bandgap semiconductor used widely in solid-state lighting. Despite numerous intriguing optical properties---including large $��^{(2)}$ and $��^{(3)}$ coefficients, a high refractive index ($>3$), and transparency from visible to long-infrared wavelengths ($0.55-11\,��$m)---its application as an integrated photonics material has been little studied. Here we introduce GaP-on-insulator as a platform for nonlinear photonics, exploiting a direct wafer bonding approach to realize integrated waveguides with 1.2 dB/cm loss in the telecommunications C-band (on par with Si-on-insulator). High quality $(Q> 10^5)$, grating-coupled ring resonators are fabricated and studied. Employing a modulation transfer approach, we obtain a direct experimental estimate of the nonlinear index of GaP at telecommunication wavelengths: $n_2=1.2(5)\times 10^{-17}\,\text{m}^2/\text{W}$. We also observe Kerr frequency comb generation in resonators with engineered dispersion. Parametric threshold powers as low as 3 mW are realized, followed by broadband ($>100$ nm) frequency combs with sub-THz spacing, frequency-doubled combs and, in a separate device, efficient Raman lasing. These results signal the emergence of GaP-on-insulator as a novel platform for integrated nonlinear photonics., 13 pages, 10 figures, 1 table; typos corrected, added/fixed references, modified title

Ionic liquid gated field-effect transistors (FETs) based on semiconducting transition metal dichalcogenides (TMDs) are used to study a rich variety of extremely interesting physical phenomena, but important aspects of how charge carriers are accumulated in these systems are not understood. We address these issues by means of a systematic experimental study of transport in monolayer MoSe$_2$ and WSe$_2$ as a function of magnetic field and gate voltage, exploring accumulated densities of carriers ranging from approximately 10$^{14}$ cm$^{-2}$ holes in the valence band to 4x10$^{14}$ cm$^{-2}$ electrons in the conduction band. We identify the conditions when the chemical potential enters different valleys in the monolayer band structure (the K and Q valley in the conduction band and the two spin-split K-valleys in the valence band) and find that an independent electron picture describes the occupation of states well. Unexpectedly, however, the experiments show very large changes in the device capacitance when multiple valleys are occupied that are not at all compatible with the commonly expected quantum capacitance contribution of these systems, $\textit{C}$$_Q$=$\textit{e}^2$/(d$\mu$/d$\textit{n}$). This unexpected behavior is attributed to the presence of a cross quantum capacitance, which originates from screening of the electric field generated by charges on one plate from charges sitting on the other plate. Our findings therefore reveal an important contribution to the capacitance of physical systems that had been virtually entirely neglected until now. (short abstract due to size limitations - full abstract in the manuscript), Comment: 5 figures

This report was designed to compare spaceflight-induced cellular and physiological adaptations of Candida albicans cultured in microgravity on the International Space Station across several payloads. C. albicans is a common opportunistic fungal pathogen responsible for a variety of superficial infections as well as systemic and more severe infections in humans. Cumulatively, the propensity of this organism to be widespread through the population, the ability to produce disease in immunocompromised individuals, and the tendency to respond to environmental stress with characteristics associated with increased virulence, require a better understanding of the yeast response to microgravity for spaceflight crew safety. As such, the responses of this yeast cultivated during several missions using two in-flight culture bioreactors were analyzed and compared herein. In general, C. albicans had a slightly shorter generation time and higher growth propensity in microgravity as compared to terrestrial controls. Rates of cell filamentation differed between bioreactors, but were low and not significantly different between flight and terrestrial controls. Viable cells were retrieved and cultured, resulting in a colony morphology that was similar between cells cultivated in flight and in terrestrial control conditions, and in contrast to that previously observed in a ground-based microgravity analog system. Of importance, yeast demonstrated an increased resistance when challenged during spaceflight with the antifungal agent, amphotericin B. Similar levels of resistance were not observed when challenged with the functionally disparate antifungal drug caspofungin. In aggregate, yeast cells cultivated in microgravity demonstrated a subset of characteristics associated with virulence. In addition, and beyond the value of the specific responses of C. albicans to microgravity, this report includes an analysis of biological reproducibility across flight opportunities, compares two spaceflight hardware systems, and includes a summary of general flight and payload timelines.

Growth of high-quality III–V nanowires at a low cost for optoelectronic and electronic applications is a long-term pursuit of research. Still, controlled synthesis of III–V nanowires using chemical vapor deposition method is challenge and lack theory guidance. Here, we show the growth of InP and GaP nanowires in a large area with a high density using a vacuum chemical vapor deposition method. It is revealed that high growth temperature is required to avoid oxide formation and increase the crystal purity of InP nanowires. Introduction of a small amount of Ga into the reactor leads to the formation of GaP nanowires instead of ternary InGaP nanowires. Thermodynamic calculation within the calculation of phase diagrams (CALPHAD) approach is applied to explain this novel growth phenomenon. Composition and driving force calculations of the solidification process demonstrate that only 1 at.% of Ga in the catalyst is enough to tune the nanowire formation from InP to GaP, since GaP nucleation shows a much larger driving force. The combined thermodynamic studies together with III–V nanowire growth studies provide an excellent example to guide the nanowire growth. Supplementary Information The online version contains supplementary material available at 10.1186/s11671-021-03505-2.

Deterministic positioning and assembly of colloidal nanoparticles (NPs) onto substrates is a core requirement and a promising alternative to top down lithography to create functional nanostructures and nanodevices with intriguing optical, electrical, and catalytic features. Capillary-assisted particle assembly (CAPA) has emerged as an attractive technique to this end, as it allows controlled and selective assembly of a wide variety of NPs onto predefined topographical templates using capillary forces. One critical issue with CAPA, however, lies in its final printing step, where high printing yields are possible only with the use of an adhesive polymer film. To address this problem, we have developed a template dissolution interfacial patterning (TDIP) technique to assemble and print single colloidal AuNP arrays onto various dielectric and conductive substrates in the absence of any adhesion layer, with printing yields higher than 98%. The TDIP approach grants direct access to the interface between the AuNP and the target surface, enabling the use of colloidal AuNPs as building blocks for practical applications. The versatile applicability of TDIP is demonstrated by the creation of direct electrical junctions for electro- and photoelectrochemistry and nanoparticle-on-mirror geometries for single particle molecular sensing.

Controlled growth of heterostructured nanowires and mechanisms of their formation have been actively studied during the last decades due to perspectives of their implementation. Here, we report on the self-catalyzed growth of axially heterostructured GaPN/GaP nanowires on Si(111) by plasma-assisted molecular beam epitaxy. Nanowire composition and structural properties were examined by means of Raman microspectroscopy and transmission electron microscopy. To study the optical properties of the synthesized nanoheterostructures, the nanowire array was embedded into the silicone rubber membrane and further released from the growth substrate. The reported approach allows us to study the nanowire optical properties avoiding the response from the parasitically grown island layer. Photoluminescence and Raman studies reveal different nitrogen content in nanowires and parasitic island layer. The effect is discussed in terms of the difference in vapor solid and vapor liquid solid growth mechanisms. Photoluminescence studies at low temperature (5K) demonstrate the transition to the quasi-direct gap in the nanowires typical for diluted nitrides with low N-content. The bright room temperature photoluminescent response demonstrates the potential application of nanowire/polymer matrix in flexible optoelectronic devices.

International audience; GnRH is a neuropeptide known to regulate reproduction in vertebrates. The purpose of this study was to design and produce recombinant gonadotropin-releasing hormone associated peptide (rGnRH/GAP) as an alternative of the previous GnRHs and native extracted hormone from tissue, to induce final maturation in fish. Decapeptide as well as GAP area sequences were compared between GnRH1, GnRH2, and mGnRH from Acipenser sp and Huso huso, respectively. Considering the conserved amino acids and the replacement of un-stable amino acids with those that were more stable against proteolytic digestion as well as had a longer half-life, the sequence was designed. The sequences of decapeptide and GAP region were synthesized and then cloned on pET28a expression vector and transformed into expression host Escherichia coli BL21(DE3). The supernatant of cultured recombinant bacteria was used for purification using TALON Metal affinity resin. The purity of the GnRH/GAP was confirmed by single 8 kDa band on SDS-PAGE and Western blot. Bioinformatics studies were performed for evaluation of homology between GnRH protein sequences and prediction of 3D protein structure using Swiss Model. The result showed that the structure prediction of the recombinant GnRH decapeptide was relatively similar to decapeptide of GnRH2 from Beluga (Huso huso). The GAP structure was similar to GAP1 of Nile tilapia (Oreochromis niloticus) and sturgeon and GnRH2 of Chinese sturgeon (Acipenser sinensis). The mass analysis showed that the sequence was exactly the same as designated sequence. Biology activity of rGnRH/GAP was tested in mature goldfish (Carassius auratus) and results showed that rGnRH/GAP had a positive effect in final maturation. Indeed 17α, 20β-dihydroxy-4-pregnen-3-one (DHP) was increased 17 h and 24 h after injection with rGnRH/GAP and spawning stemmed from that injection. These novel findings introduce the potential of utilizing rGnRH/GAP in aquaculture.

Glycidyl Azide Polymer (glycidyl polyazide) (GAP) is one of the best known energetic binders, applicable as a component increasing a calorific value of rocket propellants. In this article, a synthesis of GAP is described allowing to obtain a polymer of different molecular masses. The change of a molecular mass can influence on properties of the obtained compounds. The synthesis was carried out according to an active monomer mechanism. The obtained products were characterized using such methods as FTIR, GPC, MALDI-ToF, TG, and NMR.

In this work we study the photoinduced signatures of polarons in conjugated polymers and the impact of charge carrier delocalisation on their spectra. The variation of film crystallinity for two prototypical systems - blends of the homopolymer P3HT or the donor-acceptor polymer PCPDTBT with PCBM - allows probing changes of the polaron absorption in the mid infrared spectral region. Increased polaron delocalisation entails a shift of the electronic transition to lower energy in both cases. Also, infrared active vibrations soften due to a higher polymer chain order. Our findings help in providing a more complete understanding of polaron properties in conjugated materials and bring the application of the polaron absorption spectrum as an indicator for the environment on a more thoroughly studied foundation.

A versatile sensing scheme for gas and biomolecule detection has been proposed theoretically using optimized GaP/Au/Graphene/Silicon structures. A Gallium Phosphide (GaP) prism is used as a substrate in the proposed surface plasmon resonance based sensing scheme, which is designed to be in Kretschmann configuration. The thicknesses of different constituent layers have been optimized for the maximum values of the sensitivities of the gas and bio-sensing probes. To delineate the role of the silicon layer, sensing probes without a silicon layer have also been numerically modelled and compared. The present GaP/Au/Graphene/Silicon probes possess higher values of sensitivity for the detection of gas and biomolecules compared to the conventional SPR sensing probes reported in the literature.

Rolling bearings are the most fault-prone parts in rotating machinery. In order to find faults in time and reduce losses, this paper presents an intelligent diagnosis method for rolling bearings. At present, the deep residual network (RESNET) is the most widely used convolutional neural network (CNN) and has become one of the hotspots in fault diagnosis. However, the fully connected layer of the deep residual network has the disadvantage of too many training parameters, which makes the model training and testing time longer. So, we proposed a new network structure which the global average pooling (GAP) technology replaces the fully connected layer part of the traditional RESNET. It effectively solves the problem of too many parameters of the traditional RESNET model, and uses data enhancement, dropout, and other deep learning training techniques to prevent the model from overfitting. Experiments show that the accuracy of fault diagnosis of the improved algorithm reaches 99.83%, training time has been shortened. Also, the whole process of rolling bearing fault detection does not need any manually extract features, and this “end-to-end” algorithm has good versatility and operability.

Young's modulus of tapered mixed composition (zinc-blende with a high density of twins and wurtzite with a high density of stacking faults) gallium phosphide (GaP) nanowires (NWs) was investigated by atomic force microscopy. Experimental measurements were performed by obtaining bending profiles of as-grown inclined GaP NWs deformed by applying a constant force to a series of NW surface locations at various distances from the NW/substrate interface. Numerical modeling of experimental data on bending profiles was done by applying Euler-Bernoulli beam theory. Measurements of the nano-local stiffness at different distances from the NW/substrate interface revealed NWs with a non-ideal mechanical fixation at the NW/substrate interface. Analysis of the NWs with ideally fixed base resulted in experimentally measured Young's modulus of 155 +/- 20 GPa for ZB NWs, and 157 +/- 20 GPa for WZ NWs, respectively, which are in consistence with a theoretically predicted bulk value of 167 GPa. Thus, impacts of the crystal structure (WZ/ZB) and crystal defects on Young's modulus of GaP NWs were found to be negligible.

A Sr analogue of Ca0.5Bi0.5FeO3, Sr0.5Bi0.5FeO3, containing unusually high valence Fe3.5+ ions was synthesized by using a high-pressure technique. It relieves the electronic instability due to the unusually high valence of Fe3.5+ by a single charge disproportionation (CD) transition (Fe3.5+ -> 0.75Fe(3+) + 0.25Fe(5+)) rather than the successive CD and intermetallic charge transfer (CT) transitions seen in Ca0.5Bi0.5FeO3. Conduction-band narrowing due to the significant bend in the Fe-O-Fe bond in the rhombohedral R (3) over barc crystal structure stabilized the charge-disproportionated state at low temperatures. Most importantly, Bi3+ ions in Sr0.5Bi0.5FeO3 do not act as countercations accepting oxygen holes as they do in Ca0.5Bi0.5FeO3, resulting in the absence of the intermetallic CT transition. The large cavity of the A-site Sr ions prevents the charge-transferred Bi5+ from being stabilized. In the charge-disproportionated state the nearest-neighbor Fe3+ spins align antiferromagnetically and one-fourth of the Fe3+ spins are randomly replaced by Fe5+ spins coupled ferromagnetically with the neighboring Fe3+ spins.

In preparation of energetic composite formulations, functionally terminated pre-polymers have been used as binder. After physically mixing the pre-polymers with oxidizing components, metallic fuel, burning rate modifier and other minor ingredients, they are cured with a suitable curing agent to provide physical and chemical stability. These pre-polymers could be functionalized with carboxyl, epoxide or hydroxyl groups at varying average chain functionalities. For carboxyl-terminated pre-polymers, an epoxy functional curing agents could be used. If the pre-polymer possesses hydroxyl groups, isocyanate functional curing agents are the most suitable curing agents in terms of easy and efficient processing. Glycidyl azide polymer (GAP) is one of the well-known low-molecular weight energetic liquid pre-polymer, which was developed to use as energetic binder, high performance additive and gas generator for high performance smokeless composite propellant and explosive formulations. Linear or branched GAP can be synthesized by nucleophilic substitution reaction of corresponding poly(epichlorohydrin) (PECH) with sodium azide through replacement of chloromethyl groups of PECH with pendant energetic azido-methyl groups on the polyether main chain. Positive heat of formation (+ 957 kJ/kg) enables exothermic and rapid decomposition of GAP producing fuel rich gases. Its polyether main chain provides GAP with relatively low glass transition temperature (Tg=-48 degrees C) and presence of hydroxyl functional groups allows it to have easy processing in curing with isocyanate curing agents to form covalently crosslinked polyurethane structure. These outstanding properties of GAP enable it to be used as energetic polymeric binder and high performance additive in preparation of energetic materials and low vulnerable explosives.

With chlorinated solvents unlikely to be permitted for use in solution-processed organic solar cells in industry, there must be a focus on developing nonchlorinated solvent systems. Here we report high-efficiency devices utilizing a low-bandgap donor polymer (PffBT4T-2DT) and a nonfullerene acceptor (EH-IDTBR) from hydrocarbon solvents and without using additives. When mesitylene was used as the solvent, rather than chlorobenzene, an improved power conversion efficiency (11.1%) was achieved without the need for pre- or post-treatments. Despite altering the processing conditions to environmentally friendly solvents and room-temperature coating, grazing incident X-ray measurements confirmed that active layers processed from hydrocarbon solvents retained the robust nanomorphology obtained with hot-processed chlorinated solvents. The main advantages of hydrocarbon solvent-processed devices, besides the improved efficiencies, were the reproducibility and storage lifetime of devices. Mesitylene devices showed better reproducibility and shelf life up to 4000 h with PCE dropping by only 8% of its initial value.

The exchange of reduced carbon across the inner chloroplast envelope has a large impact on photosynthesis and growth. Under steady-state conditions it is thought that glucose 6-phosphate (G6P) does not cross the chloroplast membrane. However, growth at high CO2, or disruption of starch metabolism can result in the GPT2 gene for a G6P/Pi translocator to be expressed presumably allowing G6P exchange across the chloroplast envelope. We found that after an increase in light, the transcript for GPT2 transiently increases several 100-fold within 2 h in both the Col-0 and WS ecotypes of Arabidopsis thaliana. The increase in transcript for GPT2 is preceded by an increase in transcript for many transcription factors including Redox Responsive Transcription Factor 1 (RRTF1). The increase in GPT2 transcript after exposure to high light is suppressed in a mutant lacking the RRTF1 transcription factor. The GPT2 response was also suppressed in a mutant with a T-DNA insert in the gene for the triose-phosphate/Pi translocator (TPT). However, plants lacking TPT still had a robust rise in RRTF1 transcript in response to high light. From this, we conclude that both RRTF1 (and possibly other transcription factors) and high amounts of cytosolic triose phosphate are required for induction of the expression of GPT2. We hypothesize that transient GPT2 expression and subsequent translation is adaptive, allowing G6P to move into the chloroplast from the cytosol. The imported G6P can be used for starch synthesis or may flow directly into the Calvin-Benson cycle via an alternative pathway (the G6P shunt), which could be important for regulating and stabilizing photosynthetic electron transport and carbon metabolism.

Ternary blends with broad spectral absorption have the potential to increase charge generation in organic solar cells but feature additional complexity due to limited intermixing and electronic mismatch. Here, a model system comprising the polymers poly[5,5-bis(2-butyloctyl)-(2,2-bithiophene)-4,4-dicarboxylate-alt-5,5-2,2-bithiophene] (PDCBT) and PTB7-Th and PC70BM as an electron accepting unit is presented. The power conversion efficiency (PCE) of the ternary system clearly surpasses the performance of either of the binary systems. The photophysics is governed by a fast energy transfer process from PDCBT to PTB7-Th, followed by electron transfer at the PTB7-Th:fullerene interface. The morphological motif in the ternary blend is characterized by polymer fibers. Based on a combination of photophysical analysis, GIWAXS measurements and calculation of the intermolecular parameter, the latter indicating a very favorable molecular affinity between PDCBT and PTB7-Th, it is proposed that an efficient charge generation mechanism is possible because PTB7-Th predominantly orients around PDCBT filaments, allowing energy to be effectively relayed from PDCBT to PTB7-Th. Fullerene can be replaced by a nonfullerene acceptor without sacrifices in charge generation, achieving a PCE above 11%. These results support the idea that thermodynamic mixing and energetics of the polymer-polymer interface are critical design parameter for realizing highly efficient ternary solar cells with variable electron acceptors.

Combined experimental and theoretical approach to investigate the structural and electronic properties to Sr-doping lead titanate (PT:Sr) was carry out. It is well-known at room temperature PT crystallizes in tetragonal distorted perovskite structure with space group symmetry P4mm. At higher temperature (T > 490 °C), this compound presents a tetragonal-cubic phase transition and, due to its high tetragonality (c/a), the PT ceramics can develop cracks during the cooling process. The Sr-doping reduce this lattice anisotropy, and the doped ceramics become denser than the pure ones.The ceramic materials lead titanate (PT), lead strontium titanate (PST) and strontium titanate (ST) were synthetized by Polymeric Precursor Method. The crystal structure systems are taken from Rietveld refinement. These materials were characterized by theoretical X-ray diffraction data, total state densities (DOS), Gap values and charge maps. The gap values obtained were 3.60 eV, 3.20 eV and 3.70 eV for PT, PST and ST, respectively. The c/a ratio was investigated with different strontium concentration in the PT structure, showing that the tetragonality decreased from tetragonal to pseudo-cubic. Therefore, decreases tetragonality (c/a) and improves the physicochemical properties of the material. The presence of the atom in the PT matrix promotes an electronic stability in the strucutre of the PST inducing an improvement in the proportions of the material. In addition, ferroelectric properties can be adjusted by altering the Pb/Sr molar ratio. This behavior was associated to a lattice contraction effect caused by the diferent ionic radii between Pb and Sr. In this context, the present study characterizes the effects of Sr-doping upon structural and electronic properties of lead titanate matrix (PT). A periodic quantum-mechanical method based on DFT theory at B3LYP level has been used. These theoretical results are in agreement with the experimental. DOI: http://dx.doi.org/10.17807/orbital.v11i2.1342

"A novel square shaped air hole based photonic crystal fiber (PCF) is proposed with three symmetrical rectangular slots in the core region. A highly nonlinear material Gallium phosphide (GaP) is doped in the middle rectangular slot to achieve high nonlinearity and birefringence as well. Finite element method (FEM) is used for numerical investigation of the structure. Different optical parameters of the proposed PCF are calculated by varying its geometrical parameters. The optical parameters are optimized for the core pitch (ΛC) value between the rectangular slots as 0.18 μm. From simulation results, it can be concluded that an ultra-high nonlinear coefficient and birefringence values of 0.645 × 105 W− 1 km− 1 and 0.385 are achieved along with very low confinement loss and effective area of 2.10 × 10-08 dB/m and 4.18 × 10− 13 m2 , respectively at the centre of communication wave- length 1.55 μm. The core power fraction (CPF) is also found high as 98.056195% with extremely low effective material loss (EML) of 0.018 cm-1. Moreover, scattering loss, beat length, numerical aperture (NA), V-parameter and spot size have also been calculated. Therefore, the proposed PCF can be effectively used in single mode polarization splitter, polarization maintaining fiber, solitons generator, four wave mixer, optical signal processing, bio-medical imaging and also in sensing applications." "A novel square shaped air hole based photonic crystal fiber (PCF) is proposed with three symmetrical rectangular slots in the core region. A highly nonlinear material Gallium phosphide (GaP) is doped in the middle rectangular slot to achieve high nonlinearity and birefringence as well. Finite element method (FEM) is used for numerical investigation of the structure. Different optical parameters of the proposed PCF are calculated by varying its geometrical parameters. The optical parameters are optimized for the core pitch (ΛC) value between the rectangular slots as 0.18 μm. From simulation results, it can be concluded that an ultra-high nonlinear coefficient and birefringence values of 0.645 × 105 W− 1 km− 1 and 0.385 are achieved along with very low confinement loss and effective area of 2.10 × 10-08 dB/m and 4.18 × 10− 13 m2 , respectively at the centre of communication wave- length 1.55 μm. The core power fraction (CPF) is also found high as 98.056195% with extremely low effective material loss (EML) of 0.018 cm-1. Moreover, scattering loss, beat length, numerical aperture (NA), V-parameter and spot size have also been calculated. Therefore, the proposed PCF can be effectively used in single mode polarization splitter, polarization maintaining fiber, solitons generator, four wave mixer, optical signal processing, bio-medical imaging and also in sensing applications."

Vertical compensation friction stir welding (VCFSW) was proposed in order to solve the adverse effect caused by a big gap at the interface between two welded workpieces. VCFSW was successfully applied to weld 6061-T6 aluminum alloy with the thickness of 4 mm, while 2024-T4 aluminum alloy was selected as a rational compensation material. The results show that VCFSW is difficult to get a sound joint when the width of strip is no less than 1.5 mm. Decreasing the welding speed is beneficial to break compensation strip into pieces and then get higher quality joint. When the width of strip is 1 mm, the tensile strength and elongation of joint at the welding speed of 50 mm/min and rotational velocity of 1,800 rpm reach the maximum values of 203 MPa and 5.2%, respectively. Moreover, the addition of 2024-T4 alloy plays a strengthening effect on weld zone (WZ) of VCFSW joint. The fracture surface morphology of joint consisting of amounts of dimples exhibits ductile fracture.

Rab7 – or in yeast, Ypt7p – governs membrane trafficking in the late endocytic and autophagic pathways. Rab7 also regulates mitochondrion-lysosome contacts, the sites of mitochondrial fission. Like all Rab GTPases, Rab7 cycles between an “active” GTP-bound form that binds downstream effectors – e.g., the HOPS and retromer complexes and the dynactin-binding Rab-interacting lysosomal protein (RILP) – and an “inactive” GDP-bound form that cannot bind effectors. Accessory proteins regulate the nucleotide binding state of Rab7: guanine nucleotide exchange factors (GEFs) stimulate exchange of bound GDP for GTP, resulting in Rab7 activation, whereas GTPase activating proteins (GAPs) boost Rab7’s GTP hydrolysis activity, thereby inactivating Rab7. This review will discuss the GEF and GAPs that control Rab7 nucleotide binding, and thus regulate Rab7’s activity in endolysosomal trafficking and autophagy. It will also consider how bacterial pathogens manipulate Rab7 nucleotide binding to support intracellular invasion and immune evasion.

Aims: Bacillithiol (BSH) is the major low-molecular-weight thiol of the human pathogen Staphylococcus aureus. In this study, we used OxICAT and Voronoi redox treemaps to quantify hypochlorite-sensitive protein thiols in S. aureus USA300 and analyzed the role of BSH in protein S-bacillithiolation. Results: The OxICAT analyses enabled the quantification of 228 Cys residues in the redox proteome of S. aureus USA300. Hypochlorite stress resulted in >10% increased oxidation of 58 Cys residues (25.4%) in the thiol redox proteome. Among the highly oxidized sodium hypochlorite (NaOCl)-sensitive proteins are five S-bacillithiolated proteins (Gap, AldA, GuaB, RpmJ, and PpaC). The glyceraldehyde-3-phosphate (G3P) dehydrogenase Gap represents the most abundant S-bacillithiolated protein contributing 4% to the total Cys proteome. The active site Cys151 of Gap was very sensitive to overoxidation and irreversible inactivation by hydrogen peroxide (H2O2) or NaOCl in vitro. Treatment with H2O2 or NaOCl in the presence of BSH resulted in reversible Gap inactivation due to S-bacillithiolation, which could be regenerated by the bacilliredoxin Brx (SAUSA300_1321) in vitro. Molecular docking was used to model the S-bacillithiolated Gap active site, suggesting that formation of the BSH mixed disulfide does not require major structural changes. Conclusion and Innovation: Using OxICAT analyses, we identified 58 novel NaOCl-sensitive proteins in the pathogen S. aureus that could play protective roles against the host immune defense and include the glycolytic Gap as major target for S-bacillithiolation. S-bacillithiolation of Gap did not require structural changes, but efficiently functions in redox regulation and protection of the active site against irreversible overoxidation in S. aureus. Antioxid. Redox Signal. 28, 410–430.

Results of reverse electrophysical characteristics study of red and green LEDs, initial and irradiated with 2 MeV electrons were given. It was found that reverse current was predominantly caused by carriers tunneling at Urev ≤ 9 V, and by the avalanche multiplication at Urev ≥ 13 V, in the range U = 9 ÷ 13 V both mechanisms are available. Current increase at high voltage areas (Urev > 19 V) is limited by the base resistance of diode. In the case of significant reverse currents (I > 1 mA) irradiation of diodes leads to the shift of reverse current-voltage characteristics into the high voltages direction.

Chimaerins are a family of diacylglycerol- and phorbol ester-regulated GTPase activating proteins (GAPs) for the small G-protein Rac. Extensive evidence indicates that these proteins play important roles in development, axon guidance, metabolism, cell motility, and T cell activation. Four isoforms have been reported to-date, which are products of CHN1 (α1- and α2-chimaerins) and CHN2 (β1- and β2-chimaerins) genes. Although these gene products are assumed to be generated by alternative splicing, bioinformatics analysis of the CHN2 gene revealed that β1- and β2-chimaerins are the products of alternative transcription start sites (TSSs) in different promoter regions. Furthermore, we found an additional TSS in CHN2 gene that leads to a novel product, which we named β3-chimaerin. Expression profile analysis revealed predominantly low levels for the β3-chimaerin transcript, with higher expression levels in epididymis, plasma blood leucocytes, spleen, thymus, as well as various areas of the brain. In addition to the prototypical SH2, C1, and Rac-GAP domains, β3-chimaerin has a unique N-terminal domain. Studies in cells established that β3-chimaerin has Rac-GAP activity and is responsive to phorbol esters. The enhanced responsiveness of β3-chimaerin for phorbol ester-induced translocation relative to β2-chimaerin suggests differential ligand accessibility to the C1 domain. Fil: Zubeldia Brenner, Lautaro. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química Biológica de la Facultad de Ciencias Exactas y Naturales. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química Biológica de la Facultad de Ciencias Exactas y Naturales; Argentina Fil: Gutierrez Uzquiza, Alvaro. University of Pennsylvania; Estados Unidos Fil: Barrio Real, Laura. University of Pennsylvania; Estados Unidos Fil: Wang, Hongbin. University of Pennsylvania; Estados Unidos Fil: Kazanietz, Marcelo Gabriel. University of Pennsylvania; Estados Unidos Fil: Coluccio Leskow, Federico. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Química Biológica de la Facultad de Ciencias Exactas y Naturales. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Química Biológica de la Facultad de Ciencias Exactas y Naturales; Argentina. Universidad Nacional de Luján. Departamento de Ciencias Básicas; Argentina

International audience; in In this work, we study the effect or the different copper precursors on the structural optical and electrical properties of CuO thin films deposited on glass substrates using spray pyrolysis technique, the phase of tenorite (CuO) are identified using X-Ray diffraction. A single phase without impurities is observed for the three precursors. The band gap energy and others optical parameters are calculated using absorbance/transmittance data giving by spectrophotometry. The semiconductor aspect of our films are showed by four probes method. © 2016 IEEE.

We carried out a theoretical study on the structural stability, elastic, electronic and thermodynamic properties of the Sc x Ga 1− x P compound ( x = 0, 0.25, 0.50, 0.75 and 1) in the ZnS and NaCl crystallographic phases. For this purpose, we performed ab initio calculations using the DFT within LDA and GGA approximations. To solve the Kohn-Sham equations, we implemented the accurate full-potential linearized augmented plane wave method. From the results obtained, it can be noted that for the 0≤ x ≤0.30 range, the most stable structure of Sc x Ga 1− x P is the ZnS phase, and for the 0.30 x ≤1 interval, the most stable structure is the NaCl phase. The structural results also show a phase transition from the ZnS to NaCl at a pressure of ∼ 2.84 GPa for a Sc concentration value of 25%. Electronic band structure analysis shows that in the ZnS phase, for a 25% of Sc concentration, Sc x Ga 1− x P is a direct semiconductor, and from 50% to 100% concentrations in the NaCl phase, the compound exhibits a metallic behavior. Calculated phase diagrams predict Sc x Ga 1− x P to be stable as homogeneous alloy phases at high temperature for both ZnS and NaCl phases.

Gallium phosphide heavily doped with substitutional titanium is a prospective material for intermediate band solar cells. To manufacture such a material, single crystals of GaP were implanted with 120 keV Ti ions to doses between 5 × 1014 cm−2 and 5 × 1015 cm−2. They were next pulse annealed with 2 μs electron-beam pulses of electron energy of about 13 keV and pulse energy density between 1 and 2 Jcm−2. The samples were studied by channeled Rutherford Backscattering, particle induced X-ray emission, and SIMS. The results show full recovery of crystal structure damaged by implantation and good retention of the implanted titanium without, however, its significant substitution at crystal sites.