Single Building Block Research Articles

Grounded Meminductor Emulator using a Single Active Building Block and Its Application

Grounded Meminductor Emulator using a Single Active Building Block and Its Application

Study on tensile behavior at various temperatures of the Mg-7Gd-5Y-1Nd-2Zn-0.5Zr alloy

Mg-rare earth (RE)-Zn alloys with long-period stacking ordered (LPSO) structure show excellent room temperature, elevated temperature mechanical properties. In this work, microstructure and mechanical properties of Mg-7Gd-5Y-1Nd-2Zn-0.5Zr (wt%) alloy after tensile deformation at various temperatures (room temperature (RT), 250 °C and 300 °C) were investigated. The pre-precipitated alloy exhibited tensile yield strength (TYS) of 149 MPa at room temperature, while it maintained relatively high TYS at 250 °C (154 MPa) and 300 ℃ (123 MPa). The microstructural characterizations revealed that such outstanding heat resistance is mainly attributed to the blocky LPSO structure near the grain boundary; basal plate-like precipitates, twins and kink bands inside the grain. The blocky LPSO structure exhibits a coherent boundary with one α-Mg grain, while being incoherent with other α-Mg grains or the LPSO structure. Cracks primarily occured along the incoherent interface. Basal plate-like precipitates formed during elevated temperature tensile deformation included GP zones, γ', metastable LPSO building blocks, and fine 14H-LPSO structure. A probable γ-precipitation sequence is supersaturated solid solution → GP zones (ABAB-type) → single LPSO building block (γ')→ various metastable LPSO building block clusters→ 14H-LPSO (γ). The deformation modes (sliding, twinning, kinking, grain boundary sliding, etc) modified with the tensile temperature increase. <c+a> dislocations were observed at elevated temperatures. As the temperature of tensile test increases, twins become less. Grain boundary sliding occurs at elevated temperatures.

Generalist versus Specialist Self-Replicators.

Darwinian evolution, including the selection of the fittest species under given environmental conditions, is a major milestone in the development of synthetic living systems. In this regard, generalist or specialist behavior (the ability to replicate in a broader or narrower, more specific food environment) are of importance. Here we demonstrate generalist and specialist behavior in dynamic combinatorial libraries composed of a peptide-based and an oligo(ethylene glycol) based building block. Three different sets of macrocyclic replicators could be distinguished based on their supramolecular organization: two prepared from a single building block as well as one prepared from an equimolar mixture of them. Peptide-containing hexamer replicators were found to be generalists, i. e. they could replicate in a broad range of food niches, whereas the octamer peptide-based replicator and hexameric ethyleneoxide-based replicator were proven to be specialists, i. e. they only replicate in very specific food niches that correspond to their composition. However, sequence specificity cannot be demonstrated for either of the generalist replicators. The generalist versus specialist nature of these replicators was linked to their supramolecular organization. Assembly modes that accommodate structurally different building blocks lead to generalist replicators, while assembly modes that are more restrictive yield specialist replicators.

Pathway‐Dependent Self‐Assembly for Control over Helical Nanostructures and Topochemical Photopolymerization

AbstractPathway‐dependent self‐assembly, in which a single building block forms two or more types of self‐assembled nanostructures, is an important topic due to its mimic to the complexity in biology and manipulation of diverse supramolecular materials. Here, we report a pathway‐dependent self‐assembly using chiral glutamide derivatives (L or D‐PAG), which form chiral nanotwist and nanotube through a cooperative slow cooling and an isodesmic fast cooling process, respectively. Furthermore, pathway‐dependent self‐assembly can be harnessed to control over the supramolecular co‐assembly of PAG with a luminophore β‐DCS or a photopolymerizable PCDA. Fast cooling leads to the co‐assembled PAG/β‐DCS nanotube exhibiting green circularly polarized luminescence (CPL), while slow cooling to nanofiber with blue CPL. Additionally, fast cooling process promotes the photopolymerization of PCDA into a red chiral polymer, whereas slow cooling inhibits the polymerization. This work not only demonstrates the pathway‐dependent control over structural characteristics but also highlights the diverse functions emerged from the different assemblies.

Pathway-Dependent Self-Assembly for Control over Helical Nanostructures and Topochemical Photopolymerization.

Pathway-dependent self-assembly, in which a single building block forms two or more types of self-assembled nanostructures, is an important topic due to its mimic to the complexity in biology and manipulation of diverse supramolecular materials. Here, we report a pathway-dependent self-assembly using chiral glutamide derivatives (L or D-PAG), which form chiral nanotwist and nanotube through a cooperative slow cooling and an isodesmic fast cooling process, respectively. Furthermore, pathway-dependent self-assembly can be harnessed to control over the supramolecular co-assembly of PAG with a luminophore β-DCS or a photopolymerizable PCDA. Fast cooling leads to the co-assembled PAG/β-DCS nanotube exhibiting green circularly polarized luminescence (CPL), while slow cooling to nanofiber with blue CPL. Additionally, fast cooling process promotes the photopolymerization of PCDA into a red chiral polymer, whereas slow cooling inhibits the polymerization. This work not only demonstrates the pathway-dependent control over structural characteristics but also highlights the diverse functions emerged from the different assemblies.

Chemically fueled dynamic switching between assembly-encoded emissions.

Self-assembly provides access to non-covalently synthesized supramolecular materials with distinct properties from a single building block. However, dynamic switching between functional states still remains challenging, but holds enormous potential in material chemistry to design smart materials. Herein, we demonstrate a chemical fuel-mediated strategy to dynamically switch between two distinctly emissive aggregates, originating from the self-assembly of a naphthalimide-appended peptide building block. A molecularly dissolved building block shows very weak blue emission, whereas, in the assembled state (Agg-1), it shows cyan emission through π stacking-mediated excimer emission. The addition of a chemical fuel, ethyl-3-(3-(dimethylamino)propyl)carbodiimide (EDC), converts the terminal aspartic acid present in the building block to an intra-molecularly cyclized anhydride in situ forming a second aggregated state, Agg-2, by changing the molecular packing, thereby transforming the emission to strong blue. Interestingly, the anhydride gets hydrolyzed gradually to reform Agg-1 and the initial cyan emission is restored. The kinetic stability of the strong blue emissive aggregate, Agg-2, can be regulated by the added concentration of the chemical fuel. Moreover, we expand the scope of this system within an agarose gel matrix, which allows us to gain spatiotemporal control over the properties, thereby producing a self-erasable writing system where the chemical fuel acts as the ink.

Shape-Anisotropic Assembly of Protein Nanocages with Identical Building Blocks by Designed Intermolecular π-π Interactions.

Protein lattices that shift the structure and shape anisotropy in response to environmental cues are closely coupled to potential functionality. However, to design and construct shape-anisotropic protein arrays from the same building blocks in response to different external stimuli remains challenging. Here, by a combination of the multiple, symmetric interaction sites on the outer surface of protein nanocages and the tunable features of phenylalanine-phenylalanine interactions, a protein engineering approach is reported to construct a variety of superstructures with shape anisotropy, including 3D cubic, 2D hexagonal layered, and 1D rod-like crystalline protein nanocage arrays by using one single protein building block. Notably, the assembly of these crystalline protein arrays is reversible, which can be tuned by external stimuli (pH and ionic strength). The anisotropic morphologies of the fabricated macroscopic crystals can be correlated with the Å-to-nm scale protein arrangement details by crystallographic elucidation. These results enhance the understanding of the freedom offered by an object's symmetry and inter-object π-π stacking interactions for protein building blocks to assemble into direction- and shape-anisotropic biomaterials.

Physical Phenomena Governing Mineral Morphogenesis in Molluscan Nacre.

Mollusks, as well as many other living organisms, have the ability to shape mineral crystals into unconventional morphologies and to assemble them into complex functional mineral-organic structures, an observation that inspired tremendous research efforts in scientific and technological domains. Despite these, a biochemical toolkit that accounts for the formation of the vast variety of the observed mineral morphologies cannot be identified yet. Herein, phase-field modeling of molluscan nacre formation, an intensively studied biomineralization process, is used to identify key physical parameters that govern mineral morphogenesis. Manipulating such parameters, various nacre properties ranging from the morphology of a single mineral building block to that of the entire nacreous assembly are reproduced. The results support the hypothesis that the control over mineral morphogenesis in mineralized tissues happens via regulating the physico-chemical environment, in which biomineralization occurs: the organic content manipulates the geometric and thermodynamic boundary conditions, which in turn, determine the process of growth and the form of the biomineral phase. The approach developed here has the potential of providing explicit guidelines for the morphogenetic control of synthetically formed composite materials.

Generation and Talbot Effect of Optical Vortex Lattices with High Orbital Angular Momenta

AbstractOptical vortex lattices (OVLs) are gaining increased research attention owing to their unique features related to intensity and phase structure. Interference is a common method for generating an OVL. However, the topological charge (TC) of a single building block in an OVL is fixed and cannot be modulated, thereby limiting its applicability. This study entailed the use of phase multiplication to generate a high‐order OVL to facilitate the arbitrary modulation of its TC. The generated high‐order OVL exhibited the Talbot effect during transmission, and it transformed into a super‐honeycomb lattice at specific fractional Talbot lengths. In addition, an orbital angular momentum developed in the OVL; this has broad application prospects in optical micromanipulation. Further, a method for generating super‐honeycomb lattices is devised. The findings of this study enhances understanding of the Talbot effect and broaden the practical applicability of OVLs.

High-dimensional supervised classification in a context of non-independence of observations to identify the determining SNPs in a phenotype

This work addresses the problem of supervised classification for highly correlated high-dimensional data describing non-independent observations to identify SNPs related to a phenotype. We use a general penalized linear mixed model with a single random effect that performs simultaneous SNP selection and population structure adjustment in high-dimensional prediction models. Specifically, the model simultaneously selects variables and estimates their effects, taking into account correlations between individuals.Single nucleotide polymorphisms (SNPs) are a type of genetic variation and each SNP represents a difference in a single DNA building block, namely a nucleotide. Previous research has shown that SNPs can be used to identify the correct source population of an individual and can act in isolation or simultaneously to impact a phenotype. In this regard, the study of the contribution of genetics in infectious disease phenotypes is of great importance.In this study, we used uncorrelated variables from the construction of blocks of correlated variables done in a previous work to describe the most related observations of the dataset. The model was trained with 90% of the observations and tested with the remaining 10%. The best model obtained with the generalized information criterion (GIC) identified the SNP named rs2493311 located on the first chromosome of the gene called PRDM16 ((PR/SET domain 16)) as the most decisive factor in malaria attacks.

Pt-CsPbBr3 Perovskite Nanocrystal Heterostructures: All Epitaxial.

Designing heterostructures of soft ionic nanocrystals with metallic or covalent nanostructures having epitaxial junctions in solution poses several fundamental challenges. Hence, in spite of large successes in developing lead halide perovskite nanocrystals, the chemistry of formation of their facet-directive epitaxial growth of noble metals cannot be explored yet. To address this, herein, epitaxial heterostructures of orthorhombic CsPbBr3 and cubic Pt in multiple directional approaches are reported. Appropriate facets of perovskite nanocrystals and high-temperature reaction are the key parameters for obtaining such nanocrystal heterostructures. Interfacial planes at the junctions having ideal lattice matching helped in establishing the epitaxial relations of (110) of orthorhombic (space group Pbnm) CsPbBr3 with {020} of cubic Pt and again (011) of CsPbBr3 with {111} of Pt. These results provided strong fundamental insights that ionic halide perovskite nanostructures and materials having different crystal phases can be placed in a single building block with continuous sublattice structures.

Multi‐objective single‐shot neural architecture search via efficient convolutional filters

AbstractThis paper presents a novel approach for fast neural architecture search (NAS) in Convolutional Neural Networks (CNNs) for end‐to‐end License Plate Recognition (LPR). The authors propose a one‐shot schema that considers the efficiency of different convolutional filters to create a search space for more efficient architectures on vector processing cores. The authors’ approach utilizes a super‐network for LPR using Connectionist‐Temporal‐Cost (CTC) and ranks the importance of filters to generate a fine‐grain list of architectures. These architectures are evaluated in a multi‐objective manner, resulting in several Pareto‐optimal architectures with different computational costs and validation errors. Rather than using a single complicated building block for all layers, the authors’ method allows each stage to select a custom building block with fewer or more operations. The authors show that their super‐network is flexible to calculate filters of any required size and stride in each stage while keeping it efficient by the structural pruning. The authors’ experiments, which were performed on Iranian LPR, demonstrate that this method produces a variety of fast and efficient CNNs. Furthermore, the authors discuss the potential of this method for use in other areas of CNN application.

(NH4 )2 (I5 O12 )(IO3 ) and K1.03 (NH4 )0.97 (I5 O12 )(IO3 ): Mixed-Valent Polyiodates with Unprecedented I5 O12 - Unit Exhibiting Strong Second-Harmonic Generation Responses and Giant Birefringence.

Second-harmonic generation (SHG) response and birefringence are crucial properties for linear and nonlinear optical (NLO) materials, while it is difficult to further optimize these two key properties by using a single traditional functional building block (FBB) in one compound. Herein, a novel IO4 5- unit is identified, which possesses a square-planar configuration and two stereochemically active lone-pairs (SCALPs). By combining IO4 5- and IO3 - units, the first examples of mixed-valent polyiodates featuring an unprecedented bowl-shaped I5 O12 - polymerized unit, namely (NH4 )2 (I5 O12 )(IO3 ) and K1.03 (NH4 )0.97 (I5 O12 )(IO3 ), are successfully synthesized. Excitingly, both crystals exhibit strong SHG responses (16 × KDP and 19.5 × KDP @1064nm) as well as giant birefringence (∆nexp =0.431 and 0.405 @546nm). Detailed structure-property analyses reveal that the parallel aligned planar IO4 5- units induce the properly aligned high-density SCALPs, leading to strong SHG response and giant birefringence for both materials. This work not only provides two new potential NLO and birefringent crystals, but also discovers a novel promising FBB (IO4 5- ) for developing high-performance linear and nonlinear optical materials.

Convergent Total Synthesis of Exochelin 772SM.

A convergent total synthesis of the natural mycobacterial iron chelator desferri-exochelin 772SM (D-EXO) is described. The synthetic procedure proceeds in 11 steps in the longest linear sequence, with an overall yield of 8.6%. The described procedure uses cheap starting materials and requires a limited number of chromatographic purifications. The concise strategy divides the exochelin into five key building blocks, allowing easy alternation of each single building block. Herein, the presented synthetic strategy is well suited to facilitate the synthesis of analogues and medicinal chemistry development efforts in a time- and resource-efficient manner.

A single CCII‐based high‐precision voltage‐mode full‐wave rectifier suitable for low‐level signals

SummaryA new second‐generation current conveyor‐based full‐wave rectifier (FWR) is proposed in this work. The proposed voltage‐mode FWR comprises a single active building block, four diodes, and three grounded resistors without needing any passive element matching problems. It does not suffer from any bias voltages and/or currents; therefore, it does not need extra circuitry. It can simultaneously provide positive and negative rectifications; thus, it is flexible. The proposed FWR has high input impedance; accordingly, it can be easily cascadable. Several simulations via the SPICE program and some experiments by using the AD844s are achieved. 0.18‐μm TSMC CMOS technology parameters are used in the simulations.

Mono-material product design with bio-based, circular, and biodegradable polymers

Mono-material product design with bio-based, circular, and biodegradable polymers

Influence of Cerium oxide on the structural aspects of soda-lime aluminosilicate glasses synthesized by sol-gel route

Soda-lime aluminosilicate glasses containing different mole fractions of cerium oxide (1–10 mol.%) with a nominal composition 2xCeO2-45SiO2-15Al2O3-(20-x)Na2O-(20-x)CaO were successfully synthesized via sol-gel route. Structural and role of cerium addition were investigated via X-ray diffraction (XRD), Fourier transforms infrared (FT-IR), Raman spectroscopic, and Photoluminescence techniques. All investigated glasses show a broad diffraction band (amorphous halo) pointing to the long-range structural disorder and amorphous nature of the as-synthesized glass powder. Raman and Fourier transform infrared spectral data indicate that CeO2 plays a crucial role (network modifier) in the main soda-lime aluminosilicate network. The building groups were Qn retraced by a simple deconvolution analysis technique (DAT) and the exchange among Q3 and Q2 species can be described simply in terms of interchange in the former arrangements Si2O52− (Q3) → SiO32− (Q2), this exchange occurs with high concentrations of cerium oxide in glasses matrix. Undoped and doped soda-lime aluminosilicate photoluminescence characteristics were analyzed. PL spectrum of the undoped sample reveals significant bands caused by Na, Ca, and Al ions in silicate glasses; once the doped cerium ion was added to the glasses, two bands formed at 690 and 538 nm, which are attributed to the well-known 5d-4f cerium emission band. Computational density functional theory (DFT) was applied for a single building block of the glass network using Becke three-parameter hybrid functional (B3LYP) correlation adopting the electron core potential basis set (3-21G) was used.

Investigation of the Photocatalytic Hydrogen Production of Semiconductor Nanocrystal-Based Hydrogels.

Destabilization of a ligand-stabilized semiconductor nanocrystal solution with an oxidizing agent can lead to a macroscopic highly porous self-supporting nanocrystal network entitled hydrogel, with good accessibility to the surface. The previously reported charge carrier delocalization beyond a single nanocrystal building block in such gels can extend the charge carrier mobility and make a photocatalytic reaction more probable. The synthesis of ligand-stabilized nanocrystals with specific physicochemical properties is possible, thanks to the advances in colloid chemistry made in the last decades. Combining the properties of these nanocrystals with the advantages of nanocrystal-based hydrogels will lead to novel materials with optimized photocatalytic properties. Thisworkdemonstrates that CdSe quantum dots, CdS nanorods, and CdSe/CdS dot-in-rod-shaped nanorods as nanocrystal-based hydrogels can exhibit a much higher hydrogen production rate compared to their ligand-stabilized nanocrystal solutions. The gel synthesis through controlled destabilization by ligand oxidation preserves the high surface-to-volume ratio, ensures the accessible surface area even in hole-trapping solutions and facilitates photocatalytic hydrogen production without a co-catalyst. Especially with such self-supporting networks of nanocrystals, the problem of colloidal (in)stability in photocatalysis is circumvented. X-ray photoelectron spectroscopy and photoelectrochemical measurements reveal the advantageous properties of the 3D networks for application in photocatalytic hydrogen production.

(Re-)Directing Oligomerization of a Single Building Block into Two Specific Dynamic Covalent Foldamers through pH

Dynamic foldamers are synthetic folded molecules which can change their conformation in response to an external stimulus and are currently at the forefront of foldamer chemistry. However, constitutionally dynamic foldamers, which can change not only their conformation but also their molecular constitution in response to their environment, are without precedent. We now report a size- and shape-switching small dynamic covalent foldamer network which responds to changes in pH. Specifically, acidic conditions direct the oligomerization of a dipeptide-based building block into a 16-subunit macrocycle with well-defined conformation and with high selectivity. At higher pH the same building block yields another cyclic foldamer with a smaller ring size (9mer). The two foldamers readily and repeatedly interconvert upon adjustment of the pH of the solution. We have previously shown that addition of a template can direct oligomerization of the same building block to yet other rings sizes (including a 12mer and a 13mer, accompanied by a minor amount of 14mer). This brings the total number of discrete foldamers that can be accessed from a single building block to five. For a single building block system to exhibit such highly diverse structure space is unique and sets this system of foldamers apart from proteins. Furthermore, the emergence of constitutional dynamicity opens up new avenues to foldamers with adaptive behavior.

Homochiral hierarchical molecular assemblies through dynamic combination of conformational states of a single chiral building block at the liquid/solid interface.

We herein report the construction of homochiral, hierarchical self-assembled molecular networks (SAMNs) at the liquid/graphite interface using a single molecular building block, a chiral dehydrobenzo[12]annulene (cDBA) derivative with three chiral alkoxy and three hydroxy groups positioned in an alternating manner on the DBA core. The cDBA molecules form homochiral hierarchical SAMNs consisting of triangular clusters of several sizes, the size of which can be tuned by solvent polarity and solute concentration, reaching periodicities as large as 9.3 nm. We demonstrate the successful transmission of chirality information from the single molecular level to the hierarchical SAMN level, in a process that is mediated by dynamic self-sorting.