Basic Building Units Research Articles

The crystal chemistry of plutonium(IV) borophosphate.

In this work, we report the synthesis and characterization of a plutonium(IV) borophosphate, Pu(H2O)3[B2(OH)(H2O)(PO4)3] (1). The basic building unit of 1 has a B : P ratio of 2 : 3 with an equal number of BO4 and PO4 groups that assemble into 12-membered rings and take on a sheet topology due to presence of hydroxyl groups or a water molecule on one vertex of each BO4 tetrahedron. This unique borophosphate anion topology is not observed in other members of the borophosphate family; it is the plutonium(IV) metal centers, rather than borate or phosphate groups, that link the sheets to form an extended framework. The presence of boron in 1 was confirmed using single crystal X-ray diffraction, electron microprobe analysis, and infrared spectroscopy. Peaks corresponding to the tetrahedral BO45- and tetrahedral PO43- anions were all identified in the fingerprint region (500-1500 cm-1) of the infrared spectrum. Additionally, peaks in the higher wavenumber region corresponded to crystalline water and B-OH vibrations, providing further evidence for the water molecules surrounding plutonium in the structure and the protonation of the BO4 tetrahedron, respectively. This compound represents the first Pu(IV) borophosphate structure and a novel borophosphate anion topology. Furthermore, the long time-frame required for crystallization of 1 and the suspected leaching of boron from the borosilicate vial used during synthesis indicate that 1 could serve as a model for the crystalline materials that are expected to form during the corrosion of vitrified nuclear waste.

Development of the ship hull assembly sub-process

Objective: The development of the ship hull assembly pro-cess is possible by changing the method of assembly of basic parts at the building site, which would shorten the duration of the process and lead to cost reduction. One of the pos-sibilities is to increase the dimensions and mass of basic building units, as well as the crane capacity at the building site.Methods: Ship hull assembly methods involving sections, blocks and modules are used in the hull assembly phase. In the world’s best shipyards, ships are built from blocks or modules, in which as much equipment as possible is in-stalled. This paper uses the finite element method (FEM) for structural analysis, and its results serve to define the opti-mal technological instructions for the vertical transport of ship hull structure blocks.Results: The development of the ship hull assembly sub-pro-cess can be achieved by using the hull block assembly meth-od instead of the hull section assembly method. For the ship presented in this paper, the mass of a block transported to the building site was increased 3 times, so the number of building units was reduced by 65%. This reduces trans-port activities on the building site and shortens the dura-tion of the assembly process by 20%. This paper shows that strengthening the block structure with temporary stiffen-ers is necessary for safe transport. It is possible to optimize their number and layout by using structural analysis.Conclusion: The development of numerical finite element methods, software packages, and computers allow wider use of structural analysis in solving engineering problems in shipbuilding technology. The simulation of realistic sit-uations, a wide range of analyses and a large number of results become possible, and they raise the level of knowledge and enable better decision-making in the pro-duction process.

Rapid Synthesis of Si-Rich SSZ-13 Zeolite under Fluoride-Free Conditions

Rapid synthesis of Si-rich (SiO2/Al2O3 > 100) SSZ-13 zeolite under fluoride-free conditions is highly desirable but still challenging. Herein, we for the first time report a rapid synthesis of all silica and aluminosilicate (SiO2/Al2O3 > 100) SSZ-13 zeolite without the addition of fluoride species. The crystallization could be fully completed at 160 °C for 4 h when the aging of the starting gel is 3 h at room temperature after the addition of a zeolite seed. The key to success is the formation of more basic building units (4- and 6-membered rings) in the initial gel with the aging time of 3 h after the addition of a zeolite seed, leading to the successful rapid synthesis of Si-rich SSZ-13 zeolite. The obtained Si-rich SSZ-13 zeolite displays high crystallinity, uniform cubic morphology with a nanoparticle feature, and a large surface area. More importantly, the obtained Si-rich SSZ-13 zeolite displays excellent performance in the adsorption of ethanol and methanol-to-olefin reaction.

Three-dimensional network structured MnCo2S4/NiCo2S4 electrode materials assembled with two-dimensional nanosheets as basic building units for asymmetric supercapacitor applications

Recently, the construction of morphology and structure is considered to be one of the key factors to improve the cycle stability and rate performance of nanomaterials. Herein, MnCo2S4/NiCo2S4 (MCS/NCS) composites with three-dimensional network structures were fabricated by simple electrodeposition of NiCo2S4 nanosheets on the MnCo2S4 nanosheets framework. Compared with the two-dimensional nanosheet structure, the three-dimensional network structure of MCS/NCS has good capacitive and conductive properties. Also, the effects of electrodeposition time on the morphology and electrochemical properties of the composites were studied. Among them, MCS/NCS-6 stands out for its unique structure and excellent electrochemical properties, exhibiting excellent specific capacity (920 C g−1 at a current density of 1 A g−1) and good cycling stability. More importantly, the fabricated asymmetric supercapacitor MCS/NCS//AC assembly has a high energy density of 45.6 Wh kg−1 (800 W kg−1 power density) and good cycle life (75.6%, 10,000 cycles), demonstrating the potential application of this uniquely structured electrode material in alkaline aqueous energy storage devices such as asymmetric supercapacitors (ASC).

Bilayers as Basic Formation of Epimolecular Structure of Mostly Lyotropic (Hydrotropic) Structuralized Liquid Systems Being Influenced Predominantly by the Temperature

The bilayer’s formations of amphiphilic molecules or polyions of different ionogenity comprise the basic building units of most organic biological and non-biological systems. A theory has evolved to explain their behaviour during the creation of those organized structures, such as anisotropic liquid crystal (LC) in lyotropic (especially hydrotropic) systems and polyelectrolyte multilayer (PEM) assemblies. Particular attention has been paid to the temperature and the important role of water in the formation and behaviour of the bilayers. A novel insight into the formation of hydrotropic liquid LC systems and their thermotropic behaviour is presented. In this context, the systems PEM assemblies are also discussed. Essentially, a structuralised form of water fills out continuous and discontinuous, i.e., confined, nano-spaces among hydrophilic interfaces of bilayers, controlling their supramolecular structure through a system of attractive and repulsive hydration forces. The character of those sophisticated bonding hydration systems is predestined by the composition and type of these hydrophilic interface groups. The miscellaneous complexity of the bilayer’s aqueous systems suggests the need to study these examples in greater detail. Therefore, the bilayer’s processes connected with disruption as far as destruction of bilayers are mentioned, i.e., the processes with the highest potential to combat bacteria, fungi, and viruses, such as in a situation where a person exhales a breath of micro-droplets containing virus nanoparticles (e.g., the COVID-19 virus).

Simple naturally occurring β-carboline alkaloids – role in sustainable theranostics

Abstract This review is a brief treatise on some simple β-carboline alkaloids that are abundantly available in plants, animals and foodstuff. These alkaloids are well known for their pharmacological action as well as their allelopathic behaviour. The focus of this review is on sustainable use of naturally occurring compounds in safeguarding human health and protecting our environment at large i.e. the prospective applications of these molecules for Sustainable Theranostics . The review commences with an initial introduction to the β-carboline alkaloids, followed by an outlay of their geographical distribution and natural abundance, then the basic structure and building units of the simplest β-carboline alkaloids have been mentioned. This is followed by a discussion on the important methods of extraction from natural sources both plants and animals. Then the foundation for the use of these alkaloids in Sustainable Theranostics has been built by discussing their interesting photophysics, interactions with important biological molecules and an extensive survey of their therapeutic potential and allelopathic behaviour. Finally the review ends with a silver lining mentioning the future prospective applications of these alkaloids with special relevance to sustainability issues.

Attention-based multiscale denoising residual convolutional neural networks for fault diagnosis of rotating machinery

CNN-based fault diagnosis approaches have achieved promising results in improving the safety and reliability of rotating machinery. Most of the existing CNN models are developed on the assumption that the collected data is high-quality. However, since rotating machinery usually operates under fluctuating conditions, the critical pulse information of the measured vibration signals is easily submerged in noise. To promote the adaptability of CNN in noisy industrial scenes, an attention-based multiscale denoising residual convolutional neural network (AM-DRCN) is put forward in this study. First of all, a multiscale denoising module (MDM) is introduced as the basic building unit to help the network explore multiscale features and filter out irrelevant information. Then, a feature enhancement module (FEM) is leveraged to expand the receptive field and make full use of the side-out features. Further, a joint attention module (JAM) is explored to integrate the extracted features effectively. Finally, a lightweight CNN model named AM-DRCN is developed based on the above improvements. The practicality and effectiveness of AM-DRCN for monitoring machine health and stability states are verified through three case studies.

Enhanced Super-Resolution Using GAN

Abstract: Super-resolution reconstruction is an increasingly important area in computer vision. To eliminate the problems that super-resolution reconstruction models based on generative adversarial networks are difficult to train and contain artifacts in reconstruction results. besides the breakthroughs in accuracy and speed of single image super-resolution using faster and deeper convolutional neural networks. However, the hallucinated details are often accompanied with unpleasant artifacts. This paper presented ESRGAN model which was also based on generative adversarial networks. To further enhance the visual quality, we thoroughly study three key components of SRGAN – network architecture, adversarial loss and perceptual loss, and improve each of them to derive an Enhanced SRGAN (ESRGAN). In particular, we introduce the Residual-in-Residual Dense Block (RRDB) without batch normalization as the basic network building unit. Moreover, we borrow the idea from relativistic GAN to let the discriminator predict relative realness instead of the absolute value. Finally, we improve the perceptual loss by using the features before activation, which could provide stronger supervision for brightness consistency and texture recovery. Benefiting from these improvements, the proposed ESRGAN achieves consistently better visual quality with more realistic and natural textures than SRGAN.

Identifying Heterozipper β-Sheet in Twisted Amyloid Aggregation.

Amyloid peptide (AP) self-assembly is a hierarchical process. However, the mechanistic rule of guiding peptides to organize well-ordered nanostructure in a clear and precise manner remains poorly understood. Herein we explored the molecular insight of AP motif aggregates underlying hierarchical process with helical fibrillar structure by atomic force microscope, cryo-electron microscopy (cryo-EM), and molecular dynamics simulation. AP assembly encompasses well-ordered twisted fibrils with uniform morphology, size, and periodicity. More importantly, a heterozipper β-sheet was identified in a protofilament of AP assembly determined by cryo-EM with a high resolution of 3.5 Å. Each peptide heterozipper was further composed of two antiparallel β strands and arranged by an alternative manner in a protofilament. The hydrophobic core and hydrophilic area in each zipper played the significant role for peptide assembling. This work proposed and verified the rule facilitating the basic building unit to form twisted fibrils and gave the explanation of peptide hierarchical assembling.

Rational design via dual-site aliovalent substitution leads to an outstanding IR nonlinear optical material with well-balanced comprehensive properties.

The acquisition of a non-centrosymmetric (NCS) structure and achieving a nice trade-off between a large energy gap (E g > 3.5 eV) and a strong second-harmonic generation (SHG) response (d eff > 1.0 × benchmark AgGaS2) are two formidable challenges in the design and development of infrared nonlinear optical (IR-NLO) candidates. In this work, a new quaternary NCS sulfide, SrCdSiS4, has been rationally designed using the centrosymmetric SrGa2S4 as the template via a dual-site aliovalent substitution strategy. SrCdSiS4 crystallizes in the orthorhombic space group Ama2 (no. 40) and features a unique two-dimensional [CdSiS4]2- layer constructed from corner- and edge-sharing [CdS4] and [SiS4] basic building units (BBUs). Remarkably, SrCdSiS4 displays superior IR-NLO comprehensive performances, and this is the first report on an alkaline-earth metal-based IR-NLO material that breaks through the incompatibility between a large E g (>3.5 eV) and a strong phase-matching d eff (>1.0 × AgGaS2). In-depth mechanism explorations strongly demonstrate that the synergistic effect of distorted tetrahedral [CdS4] and [SiS4] BBUs is the main origin of the strong SHG effect and large birefringence. This work not only provides a high-performance IR-NLO candidate, but also offers a feasible chemical design strategy for constructing NCS structures.

AMoO3(IO3) (A = Na and K): Two promising optical materials via properly assembling the Λ-shaped basic building units

Herein, we reported two alkali metal molybdenum(VI) iodates, namely, NaMoO3(IO3) and γ-KMoO3(IO3) with 1D and 3D [MoO3(IO3)]− anionic architectures, respectively. The novel 1D chain in NaMoO3(IO3) and the 3D network in γ-KMoO3(IO3) are constructed by the 0D Λ-shaped cis-[MoO4(IO3)2]4− building units interconnected by bridging IO3− anions as well as the corner-sharing of oxo anions. Importantly, the polar γ-KMoO3(IO3) exhibits a very large second-harmonic generation (SHG) effect of 12 × KH2PO4 (KDP) under 1064 nm laser radiation, a high laser-Induced damage threshold value (52 × AgGaS2), and a moderate birefringence of 0.087@1064 nm, whereas the centrosymmetric NaMoO3(IO3) has a large birefringence of 0.208@1064 nm. This study further proves the useful route of exploring promising optical materials via assembling the 0D basic building units into higher dimensional anionic architectures.

Frequency Response of Electronically Tunable Current-Mode Third Order High Pass and Low Pass Filter for Q = 10

The circuits using current-mode (CM) building blocks have received considerable attention in many filtering and signal processing applications. Compared to their voltage-mode(VM) counterparts, the current-mode building blocks are attractive because of their wider bandwidth, higher slew rate, and lower power consumptions. In IC technology, it is desirable to operate circuits at low voltages which can be achieved by using CM building blocks. As a large number of op-amp based circuits with elegant realization procedures are already available, it is worthwhile to convert them into the circuits based on current-mode building blocks. In this paper, a realization of a current mode third order high pass and low pass filter is described. The proposed circuit employs operational amplifier as the basic building unit. The filter circuit realizes quadratic work function. It provides electronically tuning capability of the filter characteristics. The proposed circuit works ideal for Center frequency fo= 10 k and Circuit merit factor Q > 1. The gain roll-off this configuration is 18dB/octave. The circuit is suitable for monolithic integration and high frequency operation. The filters developed were successful in obtaining passive sensitivities less than unity in magnitude and active sensitivities are half in magnitude, which is a noteworthy achievement. The circuit is suitable for high frequency operation and monolithic integration.

Structure, magnetism, electronic properties and high magnetic-field-induced stability of alloy carbide M7C3

Previous experiments have proven that a high magnetic field can make alloy carbide M7C3 (M = Fe, Cr) precipitate ahead of time at intermediate temperatures. First-principles calculations are employed to search the source of magnetic-field-induced alloy carbides precipitation behaviors of orthorhombic M7C3. The basic building units for M7C3 crystals are polyhedrons formed by metal atoms and C atoms. The framework structure of o-M7C3 consists of metal tetrahedrons, metal octahedrons and triangular metal prisms. Magnetic calculations show that the substitution of Cr atoms causes the magnetic moments of the Fe atoms to decrease to different extents. Moreover, Cr atoms also have a magnetic moment antiparallel to the Fe atoms. Electronic structure calculations indicate that the bonds in M7C3 are a mixture of ionic, covalent and metal bonds. The substitution of Cr atoms weakens the ionic and covalent bonds between the Fe and C atoms; however, strengthen the metal bonds between the Fe and Cr atoms. The magnetic free energy change of M7C3 is larger than that of M2C and M3C at 823 K with a 12 Tesla field, which agrees well with the experimental results for a magnetic field promoting the precipitation of M7C3. This study provides a theoretical basis for the precipitation behaviors induced by magnetic fields in steels.

Penguin with bow tie-like bimetallic metal organic framework as colorimetric biosensing for H2O2 and L-cysteine

A penguin with bow tie-like bimetallic metal-organic framework, Cu3(MoO4)(TZ)2(OH)2 (Cu/Mo-MOF) {TZ = tetrazole}, was designed and fabricated by hydrothermal reaction of (NH4)6Mo7O24, Cu(NO3)2, NH4VO3 and 1H-tetrazole (HTZ). Single crystal X-ray diffraction shows the basic building unit of Cu/Mo-MOF is a “penguin shape” [6 + 6] metallocycles, which are further extended into a two-dimensional layer by “end-to-end” along the y-axis and an inverted “side by side” along the z-axis. It is interesting that the MoO4 2- anion looks like a bow tie that ties on the metallocycle improving structure stability. The bimetallic Cu/Mo-MOF was employed to detect H2O2 and L-Cys as a nanoenzyme; results from the peroxidase-like activity assay indicate the Cu/Mo-MOF possesses intrinsic peroxidase-like activity. Meanwhile, to enhance the sensor performance of Cu/Mo-MOF, the Cu/Mo-MOF/PPy nanocomposite was prepared by a chemical oxidation polymerization process of Py. Benefiting from the more active sites and the electrode/electrolyte interface, and the better electron diffusion and transport of Cu/Mo-MOF and PPy, the peroxidase-mimicking activity of the bimetallic Cu/Mo-MOF/PPy nanocomposite indeed can be greatly improved for the H2O2 and L-cysteine (L-Cys) detection, and the Cu/Mo-MOF/PPy nanocomposite exhibits a lower limit of detection (0.158 μM) among reported materials to date.

Tracing cell-type evolution by cross-species comparison of cell atlases

Cell types are the basic building units of multicellular life, with extensive diversities. The evolution of cell types is a crucial layer of comparative cell biology but is thus far not comprehensively studied. We define a compendium of cell atlases using single-cell RNA-seq (scRNA-seq) data from seven animal species and construct a cross-species cell-type evolutionary hierarchy. We present a roadmap for the origin and diversity of major cell categories and find that muscle and neuron cells are conserved cell types. Furthermore, we identify a cross-species transcription factor (TF) repertoire that specifies major cell categories. Overall, our study reveals conservation and divergence of cell types during animal evolution, which will further expand the landscape of comparative genomics.

RBDN: Residual Bottleneck Dense Network for Image Super-Resolution

Recent studies have shown that a super-resolution generative adversarial network (SRGAN) can significantly improve the quality of single-image super-resolution. However, existing SRGAN methods also have certain drawbacks, such as an insufficient feature utilization, a large number of parameters. To further enhance the visual quality, we thoroughly studied three key components of SRGAN, i.e., the network architecture, adversarial loss, and perceptual loss, and propose a DenseNet with Residual-in-Residual Bottleneck Block (RRBB), called a residual bottleneck dense network (RBDN), for single-image super-resolution. First, to improve the utilization of features between the various layers of the network, we adopted a dense cascading connection between layers. At the same time, to reduce the computational cost, we added a bottleneck structure to each layer, greatly reducing the number of network parameters and accelerating the convergence speed of the training process. Second, the proposed RRBB, as the basic network building unit, removes the batch normalization (BN) layer and employs the ELU function to reduce the opposite effects in the absence of BN. In addition, we applied an improved overall loss function during the model training process to stably train the model and further improve the realism of the reconstructed high-resolution image. To prove the superiority of our proposed model, we conducted a comprehensive and objective evaluation of the Peak Signal-to-Noise Ratio, structural similarity, learned perceptual image patch similarity, and other evaluation indicators obtained from the three test sets, i.e., Set5, Set14, and BSD100, from the recent state-of-the-art model. Finally, we conducted qualitative and quantitative analyses of the results obtained in terms of the evaluation indicators, the authenticity of the restored HR images, and textural details, which show the superiority of the RBDN model.

The synthesis of pure and uniform nanosized TS-1 crystals with a high titanium content and a high space–time yield

Concentrated basic MFI building unit species played a key role in the crystal synthesis of uniform nanosized anatase-free titanium-rich TS-1.

GhoMR: Multi-Receptive Lightweight Residual Modules for Hyperspectral Classification.

In recent years, hyperspectral images (HSIs) have attained considerable attention in computer vision (CV) due to their wide utility in remote sensing. Unlike images with three or lesser channels, HSIs have a large number of spectral bands. Recent works demonstrate the use of modern deep learning based CV techniques like convolutional neural networks (CNNs) for analyzing HSI. CNNs have receptive fields (RFs) fueled by learnable weights, which are trained to extract useful features from images. In this work, a novel multi-receptive CNN module called GhoMR is proposed for HSI classification. GhoMR utilizes blocks containing several RFs, extracting features in a residual fashion. Each RF extracts features which are used by other RFs to extract more complex features in a hierarchical manner. However, the higher the number of RFs, the greater the associated weights, thus heavier is the network. Most complex architectures suffer from this shortcoming. To tackle this, the recently found Ghost module is used as the basic building unit. Ghost modules address the feature redundancy in CNNs by extracting only limited features and performing cheap transformations on them, thus reducing the overall parameters in the network. To test the discriminative potential of GhoMR, a simple network called GhoMR-Net is constructed using GhoMR modules, and experiments are performed on three public HSI data sets—Indian Pines, University of Pavia, and Salinas Scene. The classification performance is measured using three metrics—overall accuracy (OA), Kappa coefficient (Kappa), and average accuracy (AA). Comparisons with ten state-of-the-art architectures are shown to demonstrate the effectiveness of the method further. Although lightweight, the proposed GhoMR-Net provides comparable or better performance than other networks. The PyTorch code for this study is made available at the iamarijit/GhoMR GitHub repository.

Highly Uniform All‐Vacuum‐Deposited Inorganic Perovskite Artificial Synapses for Reservoir Computing

The development of artificial synapses is inspired by the energy‐efficient recognition ability of the central nervous system of living organisms and is proposed for use as the basic building units of next‐generation neuromorphic computing networks. Herein, the perovskite/MoO3/Ag synaptic device exhibits very uniform electrical characteristics, a low operation voltage, and linear and repeatable analog switching. Important synaptic functions such as paired‐pulse facilitation (PPF) and short‐ and long‐term potentiation (STP/LTP) are all successfully and stably implemented in the device. The diffusion of Ag+ and I− ions is believed to contribute to the synaptic behavior of the device. Furthermore, the uniform and stable volatile characteristics are utilized in a proof‐of‐concept reservoir‐computing‐based simulation program using all the experimental parameters; the results strongly suggest that the neuromorphic computing that utilizes such components can simultaneously reduce the circuitry complexity and increase its recognition accuracy with noisy inputs. The findings of this work promise to significantly facilitate the utilization of highly homogeneous vacuum‐deposited perovskite/metal oxide structures in high‐performance neuromorphic computing systems.

Three-Dimensional Lead Bromide Hybrid Ferroelectric Realized by Lattice Expansion.

Three-dimensional (3D) organic-inorganic lead halide hybrids have become a hot academic topic because of their various functional properties. However, 3D lead halide hybrid ferroelectrics are still very rare until now. Here, we report a new 3D lead halide perovskite-related ferroelectric, (EATMP)Pb2Br6 [EATMP = (2-aminoethyl)trimethylphosphanium]. Based on nonferroelectric CH3NH3PbBr3, by replacing PbBr6 octahedra with a Pb2Br10 dimer of edge-sharing octahedra as the basic building unit, the expanded 3D lead bromide perovskite analog was formed with the large [EATMP]2+ cations occupying the voids of framework. Notably, (EATMP)Pb2Br6 displays a direct bandgap of 2.81 eV, four polarization directions, and a high Curie temperature (Tc) of 518 K (much beyond that of BaTiO3, 393 K), which is the highest among all reported 3D organic-inorganic hybrid ferroelectrics. Such a high Tc may result from the high rotational energy barrier of cations induced by a larger molecular volume and relatively low crystal symmetry. Our work provides an efficient avenue to construct new 3D organic-inorganic lead halide hybrids and would inspire the further exploration of 3D lead halide ferroelectrics.