Uncommon Properties Research Articles

Evaluation of Shear Strength of RC Beams Without Shear Reinforcement Using Modified Compression Field Theory

For reinforced concrete design and evaluation, the designer needs to compute the shear capacities for members based on their damage state. However, the most popular code-based shear capacity formula for RC frame members (ACI318-14) is not capable of providing such a required demand. Furthermore, for RC members with specific uncommon material properties or loading or very special detailing, code-based formula might not be applicable. The main objective of this paper is to highlight some of the shortcomings of current procedures for shear design of RC members and provide alternatives using finite element modeling. Hence, 120 shear critical rectangular beams without shear reinforcements are modeled through VecTor2 finite element program developed at the University of Toronto based on the modified compression field theory and the disturbed stress field model. The computed results are compared with published laboratory tests and ACI318-14 shear capacity estimations. The VecTor2 finite element simulations can predict the shear strength of reinforced concrete beams with an acceptable accuracy, while the ACI318-14 provisions provide imprecise estimate of shear capacity for some cases.

Технология получения жирного масла из семян томата и изучение его биохимичесих характеристик

The aim of the research is to develop the technology of obtaining tomato oil from tomato seeds and the study of the oil obtained biochemical composition. Methods . Laboratory study was carried out with the devices of the Center for Collective Use (Dagestan Scientific Center of the Russian Academy of Sciences), in the laboratories of the Mountain Botanical Garden. Specialists of Mountain Botanical Garden offered an original method for assessing the antioxidant activity of plants. Results. The physicochemical and biochemical properties of the tomato seed oil have a rich variety of composition. It is determined not only the oil fatty acid composition, but also a number of its uncommon properties. Conclusion. The research gives an idea of the rational ways of tomato seeds processing, obtained by processing the tomato mass into juices, drinks, tomato paste. Analysis of the physicochemical and biochemical parameters of tomato oil revealed its high functional properties. It is prepared the recommendations for enterprises engaged in tomato processing.

A multi-state synthetic ferrimagnet with controllable switching near room temperature

Ferrite composites with temperature-induced magnetization reversal, and synthetic ferrimagnets and antiferromagnets have been of great interest to the scientific community due to their uncommon thermal properties and potential applications in magnetic storage, spintronic devices, and several other fields. One of the advantages of these structures is the strong antiferromagnetic coupling, which stabilizes the magnetization state and gives access to interesting static and dynamical magnetic behaviors. Some of their drawbacks lie in that it is difficult to induce temperature-induced magnetization reversal at room temperature in composites, and that the strong interaction makes it difficult to induce a parallel magnetization state (and thus a high magnetic moment). In this work, we study numerically the magnetization behaviour of a Cu(1 0 0)/Ni/Pt/[Co/Pt]4 synthetic ferrimagnet and show that is possible to revert the sign of its magnetization by varying the temperature in ranges around room temperature. We also show that the four parallel and antiparallel magnetization states are stable at temperatures up to 360 K, and demonstrate that it is possible to change deterministically between these states by increasing the temperature of the device and/or applying a magnetic field, showcasing simultaneous non-hysteretic and hysteretic switching processes induced by temperature. Thus, this structure opens the possibility to have reconfigurable magnetic devices with multiple purposes based on the nature of the different switching events and the interplay between them.

A dextran with unique rheological properties produced by the dextransucrase from Oenococcus kitaharae DSM 17330

A gene encoding a novel dextransucrase was identified in the genome of Oenococcus kitaharae DSM17330 and cloned into E. coli. With a kcat of 691s−1 and a half-life time of 111h at 30°C, the resulting recombinant enzyme -named DSR-OK- stands as one of the most efficient and stable dextransucrase characterized to date. From sucrose, this enzyme catalyzes the synthesis of a quasi linear dextran with a molar mass higher than 1×109g·mol−1 that presents uncommon rheological properties such as a higher viscosity than that of the most industrially used dextran from L. mesenteroides NRRL-B-512F, a yield stress that was never described before for any type of dextran, as well as a gel-like structure. All these properties open the way to a vast array of new applications in health, food/feed, bulk or fine chemicals fields.

Characterization of YjjJ toxin of Escherichia coli.

Reminiscent of eukaryotic apoptotic programmed cell death, bacteria also contain a large number of suicide genes, which are in general co-expressed with their cognate antitoxin genes. These systems called the toxin-antitoxin (TA) systems are associated with cellular dormancy, and play major roles in biofilm formation and persistent multidrug resistance of many human pathogens. In recent years, the study on TA system toxins has become a hot topic due to the health implications of these toxins by virtue of their role in bacterial pathogenicity. Here we report functional characterization of a hitherto uncharacterized Escherichia coli TA toxin, YjjJ. YjjJ exhibits several uncommon properties: (i) unlike the genes encoding most type II TA system toxins, the gene encoding YjjJ is present as a single gene and not in an operon, (ii) despite being a homolog of the well-characterized toxin HipA, YjjJ seems to have different cellular target(s), and (iii) HipB, the cognate antitoxin of HipA, also acts as an antitoxin for YjjJ. This forms a basis for an interesting next step in the study of TA systems with respect to cross-regulation between various TA systems and the evolutionary as well as clinical significance of these observations.

Podcast: Mapping sound in the brain, dwindling groundwater, and giving iron uncommon properties

Podcast: Mapping sound in the brain, dwindling groundwater, and giving iron uncommon properties

Reducibility of ZrO2/Pt3Zr and ZrO2/Pt 2D films compared to bulk zirconia: a DFT+U study of oxygen removal and H2 adsorption.

Oxide reducibility is an important property that determines the chemical and physical behavior of the materials under working conditions. Zirconia is a non-reducible oxide that exhibits high resistance to the loss of oxygen and low reactivity towards hydrogen, two typical processes involved in oxide reduction. Oxide reducibility can change substantially by nanostructuring (e.g. formation of nanoparticles). In this study, we investigate theoretically by means of DFT+U calculations including dispersion interactions the properties of 2D zirconia films supported on a Pt3Zr alloy and Pt metal surfaces, two systems recently prepared experimentally. The results show that the supported ZrO2 ultrathin films behave very differently from the corresponding bulk oxide, with a low formation energy of oxygen vacancies, and a clear tendency to split the H2 molecule homolytically with direct reduction of the oxide. The comparison of free-standing and supported ZrO2 films shows that these peculiar properties are not due to the formation of a 2D nanostructure, but rather to the presence of the metal support and of a metal/oxide interface. The results provide evidence for the uncommon properties of supported 2D oxides.

Passive and active mechanical properties of biotemplated ceramics revisited

Living nature and human technology apply different principles to create hard, strong and tough materials. In this review, we compare and discuss prominent aspects of these alternative strategies, and demonstrate for selected examples that nanoscale-precision biotemplating is able to produce uncommon mechanical properties as well as actuating behavior, resembling to some extent the properties of the original natural templates. We present and discuss mechanical testing data showing for the first time that nanometer-precision biotemplating can lead to porous ceramic materials with deformation characteristics commonly associated with either biological or highly advanced technical materials. We also review recent findings on the relation between hierarchical structuring and humidity-induced directional motion. Finally, we discuss to which extent the observed behavior is in agreement with previous results and theories on the mechanical properties of multiscale hierarchical materials, as well as studies of highly disperse technical materials, together with an outlook for further lines of investigation.

Pole structure of theΛ(1405)in a recent QCD simulation

The $\Lambda(1405)$ baryon is difficult to detect in experiment, absent in many quark model calculations, and supposedly manifested through a two-pole structure. Its uncommon properties made it subject to numerous experimental and theoretical studies in recent years. Lattice-QCD eigenvalues for different quark masses were recently reported by the Adelaide group. We compare these eigenvalues to predictions of a model based on Unitary Chiral Perturbation Theory. The UCHPT calculation predicts the quark mass dependence remarkably well. It also explains the overlap pattern with different meson-baryon components, mainly $\pi\Sigma$ and $\bar KN$, at different quark masses. More accurate lattice QCD data are required to draw definite conclusions on the nature of the $\Lambda(1405)$.

Pseudogap formation and vacancy ordering in the new perovskite boride Zr2Ir6B

Non-oxide perovskites exhibit unusual properties such as negative thermal expansion, negative thermal coefficient of resistance, positive and negative giant magnetoresistance as well as superconductivity. These uncommon properties appear to originate from the basic structure only, in strong contrast to the oxides. Ordering in nonstoichiometric compounds may not only lead to different chemical compositions but also to the promotion of these physical properties. We present a combined NMR and first-principles study of the cubic Zr2Ir6B perovskite to investigate the boron ordering with boron deficiency leading to the formation of superstructure. Competing ionic and metallic interactions reflect the semimetallic character of this boride and result in the formation of a pseudogap, as predicted by our first principles calculations and verified experimentally by 11B solid state NMR. Several avoided crossing scenarios were also found for the bands from the conducting states at +1 eV to the Fermi level along specific directions. This observation is of paramount importance for understanding the structure-property relationships in metal boride perovskites and the search for new cubic perovskites.

The benefits of graphene for hybrid perovskite solar cells

Due to their uncommon electronic properties, carbon-based nanomaterials have led to extensive research efforts in the field of photovoltaic energy conversion in the last two decades. Initially exploiting carbon nanotubes, carbon-based solar cells have now largely taken benefit from graphene and its various forms to demonstrate significant improvements in almost all device functions including charge generation, charge collection, and charge transport. More recently, hybrid metalorganic halide perovskites became one of the most promising materials for third generation solar cells, with efficiencies now competing with thin film technologies. While several issues remain to be addressed regarding device operation and stability, the incorporation of carbon-based nanostructures was rapidly proposed, and significant advances have been achieved so far. In this work, we review the recent progresses made in the specific field of graphene-based perovskite solar cells. We especially emphasize the relevance of the approach applied to hole and electron transport media (HTM and ETM), electrodes, as well as approaches aiming at improving the stability of the device. Tandem architectures based on graphene interlayers will also be discussed, illustrating the broad potentialities of graphene materials in the development of the perovskite-based photovoltaic technology.

Type-II quantum wells with tensile-strained GaAsSb layers for interband cascade lasers with tailored valence band mixing

Optical properties of modified type II W-shaped quantum wells have been investigated with the aim to be utilized in interband cascade lasers. The results show that introducing a tensely strained GaAsSb layer, instead of a commonly used compressively strained GaInSb, allows employing the active transition involving valence band states with a significant admixture of the light holes. Theoretical predictions of multiband k·p theory have been experimentally verified by using photoluminescence and polarization dependent photoreflectance measurements. These results open a pathway for practical realization of mid-infrared lasing devices with uncommon polarization properties including, for instance, polarization-independent midinfrared light emitters.

Ultra-weak interlayer coupling in two-dimensional gallium selenide.

Beyond-graphene two-dimensional (2D) materials are envisioned as the future technology for optoelectronics, and the study of group IIIA metal monochalcogenides (GIIIAMMs) in 2D form is an emerging research field. Bulk gallium selenide (GaSe) is a layered material of this family which is widely used in nonlinear optics and is promising as a lubricant. The interlayer coupling in few-layer GaSe is currently unknown, and the stability of different polytypes is unclear. Here we use symmetry arguments and first-principles calculations to investigate the phase stability, interlayer coupling, and the Raman and infrared activity of the low-frequency shear and breathing modes expected in few-layer GaSe. Strategies to distinguish the number of layers and the β and ε polytypes are discussed. These symmetry results are valid for other isostructural few-layer GIIIAMM materials. Most importantly, by using a linear chain model, we show that the shear and breathing force constants reveal an ultra-weak interlayer coupling at the nanoscale in GaSe. These results suggest that β and ε few-layer GaSe show similar lubricant properties to those observed for few-layer graphite. Our analysis opens new perspectives about the study of interlayer interactions and their role in the mechanical and electrical properties of these new 2D materials.

Synthesis of pH-responsive amphiphilic branched macro-RAFT agent and the application in surfactant-free emulsion polymerization

Branched polymers have obviously different physical properties from their linear analogues such as low viscosity, high solubility, uncommon rheological properties and large amounts of functional groups. A series of branched poly(methyl acrylate)-block-poly(acrylic acid)s (PMA-b-HBPAAs) and branched poly(acrylic acid)-block-poly(methyl acrylate)s (PAA-b-HBPMAs) were successfully synthesized via RAFT polymerization using polyethylene glycol dimethacrylate (PEGDMA) as a branching agent, followed by a hydrolysis reaction. The structure of the branched copolymer was confirmed by Gel Permeation Chromatography (GPC), proton nuclear magnetic resonance (1H NMR) and Fourier transform infrared spectrometry (FT-IR). Then the emulsifying performance and pH responsive behavior of these amphiphilic branched macromolecules were investigated. Furthermore, these amphiphilic branched macromolecules were used as surfactants and polymerization mediators for emulsion polymerization of styrene (St) at two pH (5.5 and 12.6), respectively. Due to the balanced hydrophilicity and hydrophobicity, PMA80-b-HBPAA120 proved to be an efficient surfactant both at pH = 12.6 and pH = 5.5. The influence of the pH, the length of the hydrophilic block of the PAA segments and hydrophobic PMA segments of the amphiphilic branched macromolecule have been studied.

Zigzag-base folded sheet cellular mechanical metamaterials

The Japanese art of turning flat sheets into three dimensional intricate structures, origami, has inspired design of mechanical metamaterials. Mechanical metamaterials are artificially engineered materials with uncommon properties. Miura-ori is a remarkable origami folding pattern with metamaterial properties and a wide range of applications. In this study, by dislocating the zigzag strips of a Miura-ori pattern along the joining ridges, we create a class of one-degree of freedom (DOF) cellular mechanical metamaterials. The unit cell of the patterns comprises two zigzag strips surrounding a hole with a parallelogram shape. We show that dislocating zigzag strips of the Miura-ori along the joining ridges preserves and/or tunes the outstanding properties of the Miura-ori. The introduced materials are lighter than their corresponding Miura-ori sheets due to the presence of holes in the patterns. Moreover, they are amenable to similar modifications available for Miura-ori which make them appropriate for a wide range of applications across the length scales.

ANCF Analysis of Textile Systems

This paper presents a new flexible multibody system (MBS) approach for modeling textile systems including roll-drafting sets used in chemical textile machinery. The proposed approach can be used in the analysis of textile materials such as lubricated polyester filament bundles (PFBs), which have uncommon material properties best described by specialized continuum mechanics constitutive models. In this investigation, the absolute nodal coordinate formulation (ANCF) is used to model PFB as a hyperelastic transversely isotropic material. The PFB strain energy density function is decomposed into a fully isotropic component and an orthotropic, transversely isotropic component expressed in terms of five invariants of the right Cauchy–Green deformation tensor. Using this energy decomposition, the second Piola–Kirchhoff stress and the elasticity tensors can also be split into isotropic and transversely isotropic parts. The constitutive equations are used to define the generalized material forces associated with the coordinates of three-dimensional fully parameterized ANCF finite elements (FEs). The proposed approach allows for modeling the dynamic interaction between the rollers and PFB and allows for using spline functions to describe the PFB forward velocity. The paper demonstrates that the textile material constitutive equations and the MBS algorithms can be used effectively to obtain numerical solutions that define the state of strain of the textile material and the relative slip between the rollers and PFB.

Highly efficient organic solar cells based on a robust room-temperature solution-processed copper iodide hole transporter

Achieving high performance and reliable organic solar cells hinges on the development of stable and energetically suitable hole transporting buffer layers in tune with the electrode and photoactive materials of the solar cell stack. Here we have identified solution-processed copper(I) iodide (CuI) thin films with low-temperature processing conditions as an effective hole-transporting layer (HTL) for a wide range of polymer:fullerene bulk heterojunction (BHJ) systems. The solar cells using CuI HTL show higher power conversion efficiency (PCE) in standard device structure for polymer blends, up to PCE of 8.8%, as compared with poly(3,4-ethylenedioxy-thiophene):poly(styrenesulfonate) (PEDOT:PSS) HTL, for a broad range of polymer:fullerene systems. The CuI layer properties and solar cell device behavior are shown to be remarkably robust and insensitive to a wide range of processing conditions of the HTL, including processing solvent, annealing temperature (room temperature up to 200°C), and film thickness. CuI is also shown to improve the overall lifetime of solar cells in the standard architecture as compared to PEDOT:PSS. We further demonstrate promising solar cell performance when using CuI as top HTL in inverted device architecture. The observation of uncommon properties, such as photoconductivity of CuI and templating effects on the BHJ layer formation, is also discussed. This study points to CuI as being a good candidate to replace PEDOT:PSS in solution-processed solar cells thanks to the facile implementation and demonstrated robustness of CuI thin films.

Purpose-Oriented Antibody Libraries Incorporating Tailored CDR3 Sequences

The development of in vitro antibody selection technologies has allowed overcoming some limitations inherent to the hybridoma technology. In most cases, large repertoires of antibody genes have been assembled to create highly diversified libraries allowing the isolation of antibodies recognizing virtually any antigen. However, these universal libraries might not allow the isolation of antibodies with specific structural properties or particular amino acid contents that are rarely found in natural repertoires. Purpose-oriented libraries specially designed to incorporate desired characteristics have been successfully used. However, the workload required for library construction has limited the attractiveness of this approach compared to the use of large universal libraries. We have developed an approach to capture synthetic or natural diversity into the complementarity determining regions 3 (CDR3) of human antibody repertoires using Type IIS restriction enzymes. In this way, we generated several libraries either biased in amino acid content or towards long CDRH3 loops. The latter were successfully used to identify antibodies inhibiting the enzymatic activity of horseradish peroxidase, whereas libraries enriched in histidines allowed for the isolation of antibodies binding to human Fc in a pH-dependent manner. These libraries indicate that tailored diversification of CDR3 is sufficient to generate purpose-oriented libraries and isolate antibodies with uncommon properties.

Proton Tunneling Accelerates ATP Hydrolysis in Kinesin‐5 Proteins

It is well established that, for ATP hydrolysis, a proton from the water nucleophile is abstracted to create a hydroxide capable of attacking the substrate. Evidence for the physical basis for the catalytic power of this key reaction in biological systems has been limited until recently. X‐ray crystal structures capturing this initial step in biological ATP hydrolysis have revealed a two‐water cluster, with uncommon properties, in the active site of kinesin proteins. Herein, we tested the nature of the active‐site water cluster using solvent kinetic isotope experiments. The magnitude of the isotope effect, Arrhenius pre‐exponential factor ratios, and activation energy differences with human Kinesin‐5 proteins were determined. Our data show that the proton transfer between solvent molecules is not classical in description, but rather has a quantum mechanical tunneling component. Experiments with Drosophila Kinesin‐5 showed similar findings; moreover, X‐ray structures of the Drosophila Kinesin‐5 also captured two waters in the active site. Taken together, this is the first detection of enzymatic proton tunneling in an ATPase. More broadly, this study reveals that use of quantum biochemistry is not solely a characteristic of metalloenzymes and is more widespread than currently established. This work was supported by NIH GM097350 (SK).

New patterns in human biogeography revealed by networks of contacts between linguistic groups

Human languages differ broadly in abundance and are distributed highly unevenly on the Earth. In many qualitative and quantitative aspects, they strongly resemble biodiversity distributions. An intriguing and previously unexplored issue is the architecture of the neighbouring relationships between human linguistic groups. Here we construct and characterize these networks of contacts and show that they represent a new kind of spatial network with uncommon structural properties. Remarkably, language networks share a meaningful property with food webs: both are quasi-interval graphs. In food webs, intervality is linked to the existence of a niche space of low dimensionality; in language networks, we show that the unique relevant variable is the area occupied by the speakers of a language. By means of a range model analogous to niche models in ecology, we show that a geometric restriction of perimeter covering by neighbouring linguistic domains explains the structural patterns observed. Our findings may be of interest in the development of models for language dynamics or regarding the propagation of cultural innovations. In relation to species distribution, they pose the question of whether the spatial features of species ranges share architecture, and eventually generating mechanism, with the distribution of human linguistic groups.