Large Modifications Research Articles

Polysialic acid is a cellular receptor for human adenovirus 52

Human adenovirus 52 (HAdV-52) is one of only three known HAdVs equipped with both a long and a short fiber protein. While the long fiber binds to the coxsackie and adenovirus receptor, the function of the short fiber in the virus life cycle is poorly understood. Here, we show, by glycan microarray analysis and cellular studies, that the short fiber knob (SFK) of HAdV-52 recognizes long chains of α-2,8-linked polysialic acid (polySia), a large posttranslational modification of selected carrier proteins, and that HAdV-52 can use polySia as a receptor on target cells. X-ray crystallography, NMR, molecular dynamics simulation, and structure-guided mutagenesis of the SFK reveal that the nonreducing, terminal sialic acid of polySia engages the protein with direct contacts, and that specificity for polySia is achieved through subtle, transient electrostatic interactions with additional sialic acid residues. In this study, we present a previously unrecognized role for polySia as a cellular receptor for a human viral pathogen. Our detailed analysis of the determinants of specificity for this interaction has general implications for protein-carbohydrate interactions, particularly concerning highly charged glycan structures, and provides interesting dimensions on the biology and evolution of members of Human mastadenovirus G.

Modified Ca-Graphite Intercalation Compounds As Anode Material for Li Ion Batteries

Due to the increasing demands for the high capacity lithium ion batteries (LIBs) for use in mobile devices and electric vehicles, a new anode material with a higher capacity than that of graphite (372 mAh/g) is desired. As a candidate of such anode material, alloy-type anode (Si, Ge, Sn, etc.) shows much higher capacity than that of graphite [1]. However, their large volume modification during the charge-discharge process limits their cyclic performances. On the other hand, high capacity carbon based materials, such as graphene sheets, carbon nanotubes and nanofibers have also attracted much attention [1]. For practical use, their high intercalation potential of lithium and the difficulty of mass-production of these materials have to be overcome. In this study, we report a new type of high capacity carbon based material, Ca0.6-xB1.2C4.8. It is a novel material obtained by one-pot heat-treatment of graphite with boron and calcium sources. Its highly ordered graphite-like layer structure distinguishes it from the former reported high capacity carbon based materials, such as graphene sheets, carbon nanotubes and nanofibers. Its specific capacity was 552 mAh/g, which is much higher than that of graphite. This result suggests the possibility of realizing a yet higher capacities for graphite based materials. The detailed preparation method, characterization, and electrochemical measurements will be discussed on the session.

High Performance Triboelectric Nanogenerator by Hot Embossing on Self‐Assembled Micro‐Particles

Triboelectric nanogenerator (TENG) is a novel technology for energy harvesting and active sensing which shows a great potential toward extracting the ambient kinetic energy. The surface morphology of triboelectric layers is one of the most important elements for enhancing the output of TENG devices. Current surface modification methods mostly require complicated, long term, size limited, and costly processes. This paper presents a cost effective, facile, repeatable, and fast method for large scale surface modification of triboelectric layers which significantly enhance the performance of TENG devices. This method simply utilizes the hot‐embossing of polymers on self‐assembled micro‐particles to create semi‐ordered micro‐sized structures on the surfaces. The modified surfaces increase the output performance of the TENG such as open circuit voltage and short circuit current for more than four times. As the presence of water degrades the output of TENG, this technique is very beneficial to remarkably improve the hydrophobicity of the contact layers. The proposed method can be applied to a variety of polymers with an area scalable fabrication toward the use of TENG in real world industrial applications.

Large distance modification of Newtonian potential and structure formation in universe

In this paper, we study the effects of super-light brane world perturbative modes on structure formation in our universe. As these modes modify the large distance behavior of Newtonian potential, they effect the clustering of a system of galaxies. So, we explicitly calculate the clustering of galaxies interacting through such a modified Newtonian potential. We use a suitable approximation for analyzing this system of galaxies, and discuss the validity of such approximations. We observe that such corrections also modify the virial theorem for such a system of galaxies.

Slowly-rotating neutron stars in massive bigravity

We study slowly-rotating neutron stars in ghost-free massive bigravity. This theory modifies general relativity by introducing a second, auxiliary but dynamical tensor field that couples to matter through the physical metric tensor through non-linear interactions. We expand the field equations to linear order in slow rotation and numerically construct solutions in the interior and exterior of the star with a set of realistic equations of state. We calculate the physical mass function with respect to observer radius and find that, unlike in general relativity, this function does not remain constant outside the star; rather, it asymptotes to a constant a distance away from the surface, whose magnitude is controlled by the ratio of gravitational constants. The Vainshtein-like radius at which the physical and auxiliary mass functions asymptote to a constant is controlled by the graviton mass scaling parameter, and outside this radius, bigravity modifications are suppressed. We also calculate the frame-dragging metric function and find that bigravity modifications are typically small in the entire range of coupling parameters explored. We finally calculate both the mass-radius and the moment of inertia-mass relations for a wide range of coupling parameters and find that both the graviton mass scaling parameter and the ratio of the gravitational constants introduce large modifications to both. These results could be used to place future constraints on bigravity with electromagnetic and gravitational-wave observations of isolated and binary neutron stars.

Quasi-static method and finite element method for obtaining the modifications of the spontaneous emission rate and energy level shift near a plasmonic nanostructure.

We provide numerical demonstrations of the applicability and accuracy of the quasi-static method and the finite-element method in the investigation of the modifications of the spontaneous emission rate and the energy level shift of an emitter placed near a silver-air interface or a silver nano-sphere. The analytical results are presented as a reference. Our calculations show that the finite element method is an accurate and general method. For frequency away from the radiative mode, the quasi-static method can be applied more effectively for calculating the energy level shift than the spontaneous emission rate. But for frequency around, there is a blue shift for both and this shift increases with the increasing of emitter-silver distance. Applying the theory to the nanosphere dimmer, we see similar phenomenon and find extremely large modifications of the spontaneous emission rate and energy level shift. These findings are instructive in the fields of quantum light-matter interactions.

Pyrenyl-carbon nanostructures for scalable enzyme electrocatalysis and biological fuel cells.

The objective of this article is to demonstrate the electrode geometric area-based scalability of pyrenyl-carbon nanostructure modification for enzyme electrocatalysis and fuel cell power output using hydrogenase anode and bilirubin oxidase cathode as the model system.

Electroweak baryogenesis and the standard model effective field theory

We investigate electroweak baryogenesis within the framework of the Standard Model Effective Field Theory. The Standard Model Lagrangian is supplemented by dimension-six operators that facilitate a strong first-order electroweak phase transition and provide sufficient CP violation. Two explicit scenarios are studied that are related via the classical equations of motion and are therefore identical at leading order in the effective field theory expansion. We demonstrate that formally higher-order dimension-eight corrections lead to large modifications of the matter-antimatter asymmetry. The effective field theory expansion breaks down in the modified Higgs sector due to the requirement of a first-order phase transition. We investigate the source of the breakdown in detail and show how it is transferred to the CP-violating sector. We briefly discuss possible modifications of the effective field theory framework.

Production and Chemoselective Modification of Adeno-Associated Virus Site-Specifically Incorporating an Unnatural Amino Acid Residue into Its Capsid.

The ability to modify the capsid proteins of human viruses is desirable both for installing probes to study their structure and function, and to attach retargeting agents to engineer viral infectivity. However, the installation of such capsid modifications currently faces two major challenges: (1) The complex and delicate capsid proteins often do not tolerate large modifications, and (2) capsid proteins are composed of the 20 canonical amino acids, precluding site-specific chemical modification of the virus. Here, we describe a technology for generating adeno-associated virus (AAV) while incorporating an unnatural amino acid (UAA) into specific sites of the virus capsid. Incorporation of this UAA is generally tolerated well, presumably due to its small structural footprint. The resulting virus can be precisely functionalized at the site of UAA incorporation using chemoselective conjugation strategies targeted toward the azido side chain of this UAA. This technology provides a powerful way to modify AAV with unprecedented precision to both probe and engineer its entry process.

Renormalization of photon dyadic Green function by finite element method and its applications in the study of spontaneous emission rate and energy level shift

The spontaneous emission rate and the energy level shift of a quantum dot in any micro-nanostructures can be expressed by the classical dyadic Green's function. However, the real part of the dyadic Green's function is divergent, when the source point and the field point are at the same position. This leads to an unphysical divergent level shift. Theoretically, the dyadic Green's function can be decomposed into a homogeneous part and a scattering part. Traditionally, the homogeneous field contribution is introduced into the definition of the transition frequency and the only need is to consider the effect of the scattering part which is non-divergent. Another renormalization method is to average the Green tensor over the volume of the quantum dot. In this work, a finite element method is proposed to address this problem. The renormalized dyadic Green function is expressed by the averaged radiation field of a point dipole source over the quantum dot volume. For the vacuum case, numerical results of the renormalized Green tensor agree well with the analytical ones. For the nanosphere model, the renormalized scattering Green tensor, which is the difference between the renormalized Green tensor and the analytical renormalized one in homogeneous space, agrees well with the analytical scattering Green tensor in the center of the quantum dot. Both of the above models clearly demonstrate the validity and accuracy of our method. Compared with the previous scattering Green function method where two different finite element runs are needed for one frequency point, our renormalization method just needs one single run. This greatly reduces the computation burden. Applying the theory to a gap plasmonic nano-cavity, we find extremely large modifications for the spontaneous emission rate and the energy level shift which are independent of the size of the quantum dot. For frequency around the higher order mode of the nano-cavity, spontaneous emission enhancement is about Г/Г0 2.02106 and the energy level shift is about △ 1000 meV for a dipole moment 24D. These findings are instructive in the fields of quantum light-matter interactions.

Environmental heterogeneity at small spatial scales affects population and community dynamics on intertidal rocky shores of a threatened bay system

Coastal areas are critical transition zones between marine and terrestrial domains that support a large diversity of species but are exposed to significant anthropogenic impacts. While most conservation and management strategies rely on understanding the drivers of diversity over large scales, the importance of small-scale variation in environmental conditions can be overlooked. Here we combined a descriptive and experimental approach to describe the spatio-temporal dynamics of sessile communities and of the population of the barnacle Chthamalus bisinuatus within Araçá Bay, a transition zone in southeastern Brazil threatened by the expansion of the São Sebastião Port. We compared the relative coverage of sessile organisms from rocky shores for 20 months and several population parameters of barnacles in three distinct regions of Araçá Bay, a few hundred meters apart: the inner portion, close to the Mãe Isabel River and the Port, the middle of the Bay, and the outer region, close to the bay entrance. Community structure varied significantly over these small spatial scales; the macroalga Ulva lactuca and the oyster Crassostrea sp. were more abundant in the inner portion of the Bay, where the influence of freshwater and organic pollution from Mãe Isabel River is more intense. Recruitment and density of C. bisinuatus was higher on the shores close to the mouth of the Bay, but individual size increased as one moves into the bay. Experimental manipulation of barnacles originally recruiting at the outer part of the bay and translocated to both outer and inner positions showed that while recruitment is restricted at the inner region, barnacle growth and survival are higher than at the outer shore. Our results suggest that the gradient of physical conditions created along the Araçá Bay can result in distinct dynamics of communities and populations and that the region close to the mouth of the bay is more dynamic, with a larger turnover of space. In the opposite direction, the inner part of the bay, which is closer to the São Sebastião Port, is more prone to be disturbed by any large human modification on the coast as populations are less dynamic and communities tend to be monopolized by species associated with organic pollution. Besides providing useful data for the management of Araçá Bay, our results also show that small-scale variation of environmental conditions can contribute to create distinct dynamics of populations and communities and should be addressed in assessments of environmental impacts on the coast.

Polyatomic ions from a high current ion implanter driven by a liquid metal ion source.

High current liquid metal ion sources are well known and found their first application as field emission electric propulsion thrusters in space technology. The aim of this work is the adaption of such kind of sources in broad ion beam technology. Surface patterning based on self-organized nano-structures on, e.g., semiconductor materials formed by heavy mono- or polyatomic ion irradiation from liquid metal (alloy) ion sources (LMAISs) is a very promising technique. LMAISs are nearly the only type of sources delivering polyatomic ions from about half of the periodic table elements. To overcome the lack of only very small treated areas by applying a focused ion beam equipped with such sources, the technology taken from space propulsion systems was transferred into a large single-end ion implanter. The main component is an ion beam injector based on high current LMAISs combined with suited ion optics allocating ion currents in the μA range in a nearly parallel beam of a few mm in diameter. Different types of LMAIS (needle, porous emitter, and capillary) are presented and characterized. The ion beam injector design is specified as well as the implementation of this module into a 200 kV high current ion implanter operating at the HZDR Ion Beam Center. Finally, the obtained results of large area surface modification of Ge using polyatomic Bi2+ ions at room temperature from a GaBi capillary LMAIS will be presented and discussed.

Effects of the Protonation State of Titratable Residues and the Presence of Water Molecules on Nocodazole Binding to β-Tubulin.

Regulation of microtubule assembly by antimitotic agents is a potential therapeutic strategy for the treatment of cancer, parasite infections, and neurodegenerative diseases. One of these agents is nocodazole (NZ), which inhibits microtubule polymerization by binding to β-tubulin. NZ was recently co-crystallized in Gallus gallus tubulin, providing new information about the features of interaction for ligand recognition and stability. In this work, we used state-of-the-art computational approaches to evaluate the protonation effects of titratable residues and the presence of water molecules in the binding of NZ. Analysis of protonation states showed that residue E198 has the largest modification in its pKa value. The resulting E198 pKa value, calculated with pH-REMD methodology (pKa =6.21), was higher than the isolated E amino acid (pKa =4.25), thus being more likely to be found in its protonated state at the binding site. Moreover, we identified an interaction between a water molecule and C239 and G235 as essential for NZ binding. Our results suggest that the protonation state of E198 and the structural water molecules play key roles in the binding of NZ to β-tubulin.

Influence of antistatic agent encapsulated into functionalized mesoporous silica on antistatic properties of polystyrene

ABSTRACTSmall molecular surfactant (SMS) such as HDC-193 was encapsulated into mesoporous silica SBA-15 and 3-aminopropyltriethoxysilane-modified SBA-15 (mSBA-5) to develop new controlled release SMS system. The diffusion process of HDC-193 from mesoporous silica with different structures and diameters was investigated. Both situations of large pore and organic modification promoted the adsorption and thus a larger load of SMS in mesoporous silica. The results of molecular dynamics simulations and washing durability experiments showed that the lifetime of HDC-193 encapsulated into mSBA-15 in polystyrene blends is five times longer than that of HDC-193/polystyrene. This suggests an efficient strategy for designing permanent antistatic agents.

High field induced magnetic transitions in the Y0.7Er0.3Fe2D4.2 deuteride

The influence of the partial Er for Y substitution on the crystal structure and magnetic properties of $\mathrm{YF}{\mathrm{e}}_{2}{\mathrm{D}}_{4.2}$ has been investigated by high field magnetization and neutron diffraction experiments. ${\mathrm{Y}}_{0.7}\mathrm{E}{\mathrm{r}}_{0.3}\mathrm{F}{\mathrm{e}}_{2}{\mathrm{D}}_{4.2}$ compound crystallizes in the same monoclinic structure as $\mathrm{YF}{\mathrm{e}}_{2}{\mathrm{D}}_{4.2}$ described in $Pc\phantom{\rule{0.28em}{0ex}}({P}_{1}{c}_{1})$ space group with D atoms located in 18 different tetrahedral interstitial sites. A cell volume contraction of 0.6% is observed upon Er substitution, inducing large modification of the magnetic properties. Electronic effect of D insertion as well as lowering of crystal symmetry are important factors determining the magnetic properties of Fe sublattice, which evolves towards more delocalized behavior and modifying the Er-Fe exchange interactions. In the ground state, the Er and Fe moments are arranged ferrimagnetically within the plane perpendicular to the monoclinic $b$ axis and with average moments ${m}_{\mathrm{Er}}=6.4(3){\ensuremath{\mu}}_{B}{\mathrm{Er}}^{\ensuremath{-}1}$ and ${\mathrm{m}}_{\mathrm{Fe}}=2.0(1){\ensuremath{\mu}}_{B}{\mathrm{Fe}}^{\ensuremath{-}1}$ at 10 K. Upon heating, ${m}_{\mathrm{Er}}$ decreases progressively until ${T}_{\mathrm{Er}}=55\phantom{\rule{0.16em}{0ex}}\mathrm{K}$. Between 55 K and 75 K, the Fe sublattice undergoes a first-order ferromagnetic-antiferromagnetic (FM-AFM) transition with a cell volume contraction due to the itinerant metamagnetic behavior of one Fe site. In the AFM structure, ${m}_{\mathrm{Fe}}$ decreases until the N\'eel temperature ${T}_{\mathrm{N}}=125\phantom{\rule{0.16em}{0ex}}\mathrm{K}$. At high field, two different types of field induced transitions are observed. The Er moments become parallel to the Fe one and saturates to the $\mathrm{E}{\mathrm{r}}^{3+}$ free ion value, leading to an unusual field induced FM arrangement at a transition field ${B}_{\mathrm{Trans}}$ of only 78 kG below 30 K. Then above ${{T}_{\mathrm{M}}}_{0}=66\phantom{\rule{0.16em}{0ex}}\mathrm{K}$, an AFM-FM transition of the Fe sublattice, accompanied by a cell volume increase is observed. ${B}_{\mathrm{Trans}}$ increases linearly versus temperature and with a larger $d{B}_{\mathrm{Trans}}/dT$ slope than for $\mathrm{YF}{\mathrm{e}}_{2}{\mathrm{D}}_{4.2}$. This has been explained by the additional contribution of Er induced moments above ${B}_{\mathrm{Trans}}$.

Simulation of African dust properties and radiative effects during the 2015 SHADOW campaign in Senegal

The aim of this work is to estimate optical and radiative properties of dust aerosols and their potential feedbacks on atmospheric properties over Western Africa for the period 20 March–28 April 2015, by using numerical simulations and different sets of remote-sensing and in-situ measurements. Comparisons of simulations made by the on-line coupled meteorological-chemistry model WRF-CHEM with MODIS, AERONET and in-situ observations result in a general agreement for the spatio-temporal variations of aerosol extinction at both local and regional scales. Simulated SSA reached elevated values between 0.88 and 0.96 along the visible/near-infrared in close agreement with AERONET inversions, suggesting the predominance of dust over Western Africa during this specific period. This predominance of dust is confirmed by in-situ measurements of the aerosol size distribution, fitting well with the aerosols size distribution simulated by WRF-CHEM. The impact of this large dust load on the radiative fluxes leads to large modifications of the shortwave and longwave radiative budget both at the ground and at the top of the atmosphere. In return, the response of the atmosphere to these dust-induced radiative changes is the alteration of the surface air temperature and wind fields, with non-negligible impact on the dust emission and transport.

Level of Theory and Solvent Effects on DASA Absorption Properties Prediction: Comparing TD-DFT, CASPT2 and NEVPT2.

Donor–acceptor Stenhouse adducts (DASAs) are a very recent class of organic photoswitches that combine excellent properties, such as color and polarity change, a large structural modification, and excellent fatigue resistance. Despite their potential applications in different fields, very few studies have focused on rationalizing their electronic structure properties. Here, by means of different state-of-the-art theoretical methods, including solvent and vibrational effects, we show that while time dependent-density functional theory (TD-DFT) can qualitatively describe DASAs’ excited states, multiconfigurational quantum chemistry methods along with dynamic electron correlation (CASPT2, NEVPT2) are required for a quantitative agreement with the experiment. This finding is reasoned based on the different charge transfer characteristics observed. Moreover, the TD-DFT computed two-photon absorption properties are reported and suggested to red-shift the absorption band, as required for biological applications.

Structural dynamic reanalysis method for transonic aeroelastic analysis with global structural modifications

Transonic aeroelastic analysis is an important aspect of modern aircraft design. When the modeshapes changed for the structural stiffness or/and mass matrix variation, the structural model and aerodynamic model could be reconstructed to maintain accuracy. However, these reconstruction procedures have to be repeated every time when there is a change in the aircraft structure design, where each of these reconstructions takes a considerable time. In this paper, an automated procedure for transonic aeroelastic analysis method was proposed when the structural model parameters changed at global level. To manage thousands of calculations and makes more efficient and reliable calculations, the structural dynamic reanalysis method was employed to set up an automated procedure to link the aeroelastic solvers and structural design parameters without changing structural modal coordinates. The proposed automated procedure was illustrated and verified by the AGARD 445.6 wing aeroelastic model with different global level structural parameter variations. The results show that the automated procedure can accurately produce pulse responses corresponding to the mode excitations and the flutter characteristics of AGARD 445.6 wing in a very large modification range. The whole automated procedure is efficient and reliable in managing transonic aeroelastic analysis when structural parameters changed at global level.

Effects of different irrigation strategies on the evolution of peat hydraulic properties during cultivation

The combined effects of root development and irrigation strategies on the physical and hydraulic properties of peat substrates were studied within a culture of Rosa × hybrida ‘Radrazz’ during five months when watering was managed in three different ways: (1) water potential always maintained at container capacity, (2) irrigation triggered when water potential reached -10 kPa or (3) -30 kPa. Root volume, total volume, air and water retention properties, saturated hydraulic conductivity, relative gas diffusivity, and wettability were measured at the beginning and then at the end of the experiment. The study showed important changes over time, mainly due to the hydric history, and the irrigation strategies leading to large modifications of pore size distribution and connectivity. Furthermore, the intensity of drying amplified the degradation of peat wettability, and altered the physical qualities of peat. However, positive effects of the root system were shown by limiting the decrease in wettability.

Adsorbed Dyes onto Nanoparticles: Large Wavelength Dependence in Second Harmonic Scattering

Spectrally and polarization resolved second harmonic scattering (SHS) has been used to probe the adsorption of an hemicyanine dye onto polystyrene nanoparticles. The polarization resolved SHS measurements in both the vertically and horizontally output polarization configuration demonstrate the ability of this technique to monitor simultaneously the amount of free dye in solution and the amount of dye species adsorbed onto nanoparticles. Indeed, those two contributions can be discriminated when changing the laser incident polarization angle. Moreover, a large modification appears for the horizontally polarization resolved pattern when the laser excitation wavelength is tuned from 790 to 810 nm. This result is discussed within the framework of nonlinear Mie theory.