Estimating Natural Frequencies of Cartesian 3D Printer Based on Kinematic Scheme

Nowadays, 3D printers based on Cartesian kinematics are becoming extremely popular due to their reliability and inexpensiveness. In the early stages of the 3D printer design, once it is chosen to use the Cartesian kinematics, it is always necessary to select relative positions of axes and linear drives (prismatic joints), which would be optimal for the particular specification. Within the class of Cartesian mechanics, many designs are possible. Using the Euler–Lagrange formalism, this paper introduces a method for estimating the natural frequencies of Cartesian 3D printers based on the kinematic scheme. Comparison with the finite element method and experimental validation of the proposed method are given. The method can help to develop preliminary designs of Cartesian 3D printers and is especially useful for emerging 3D-printing technologies

Image preprocessing for artistic robotic painting

Artistic robotic painting implies creating a picture on canvas according to a brushstroke map preliminarily computed from a source image. To make the painting look closer to the human artwork, the source image should be preprocessed to render the effects usually created by artists. In this paper, we consider three preprocessing effects: aerial perspective, gamut compression and brushstroke coherence. We propose an algorithm for aerial perspective amplification based on principles of light scattering using a depth map, an algorithm for gamut compression using nonlinear hue transformation and an algorithm for image gradient filtering for obtaining a well-coherent brushstroke map with a reduced number of brushstrokes, required for practical robotic painting. The described algorithms allow interactive image correction and make the final rendering look closer to a manually painted artwork. To illustrate our proposals, we render several test images on a computer and paint a monochromatic image on canvas with a painting robot

Spatial Anisotropies and Temporal Fluctuations in Extracellular Matrix Network Texture during Early Embryogenesis

Early stages of vertebrate embryogenesis are characterized by a remarkable series of shape changes. The resulting morphological complexity is driven by molecular, cellular, and tissue-scale biophysical alterations. Operating at the cellular level, extracellular matrix (ECM) networks facilitate cell motility. At the tissue level, ECM networks provide material properties required to accommodate the large-scale deformations and forces that shape amniote embryos. In other words, the primordial biomaterial from which reptilian, avian, and mammalian embryos are molded is a dynamic composite comprised of cells and ECM. Despite its central importance during early morphogenesis we know little about the intrinsic micrometer-scale surface properties of primordial ECM networks. Here we computed, using avian embryos, five textural properties of fluorescently tagged ECM networks — (a) inertia, (b) correlation, (c) uniformity, (d) homogeneity, and (e) entropy. We analyzed fibronectin and fibrillin-2 as examples of fibrous ECM constituents. Our quantitative data demonstrated differences in the surface texture between the fibronectin and fibrillin-2 network in Day 1 (gastrulating) embryos, with the fibronectin network being relatively coarse compared to the fibrillin-2 network. Stage-specific regional anisotropy in fibronectin texture was also discovered. Relatively smooth fibronectin texture was exhibited in medial regions adjoining the primitive streak (PS) compared with the fibronectin network investing the lateral plate mesoderm (LPM), at embryonic stage 5. However, the texture differences had changed by embryonic stage 6, with the LPM fibronectin network exhibiting a relatively smooth texture compared with the medial PS-oriented network. Our data identify, and partially characterize, stage-specific regional anisotropy of fibronectin texture within tissues of a warm-blooded embryo. The data suggest that changes in ECM textural properties reflect orderly time-dependent rearrangements of a primordial biomaterial. We conclude that the ECM microenvironment changes markedly in time and space during the most important period of amniote morphogenesis—as determined by fluctuating textural properties

A Robot for Artistic Painting in Authentic Colors

Artistic robotic painting automates the process of creating an artwork. This complex and challenging task includes several aspects: creating algorithms for rendering brushstrokes, reproducing the exact shape of a brushstroke, and developing the principles of mixing paints. This work contributes to the previously unsolved problem of accurately reproducing colors of brushstrokes by means of artistic paints. The main contributions of this paper include: the development of a novel 4-component data-driven mathematical model for artistic paint mixing; the design and implementation of a novel robot capable of accurately dosing and mixing acrylic paints thanks to the improved syringe pumps and the innovative paint mixer; the development of a novel pneumatic system for paint release with a build-in clogging detection mechanism. The capabilities of the designed robotic system are demonstrated by painting four artworks: replicas of Claude Monet’s and Arkady Rylov’s landscapes, a synthetic image generated using the StyleGAN2 neural network trained on Vincent van Gogh’s artistic heritage, and a synthetic image generated using the Midjourney neural network. The obtained results can be useful in various applications of computer creativity, as well as in artistic image replication and restoration, and also in colored 3D printing

A two-parameter modified logistic map and its application to random bit generation

This work proposes a modified logistic map based on the system previously proposed by Han in 2019. The constructed map exhibits interesting chaos related phenomena like antimonotonicity, crisis, and coexisting attractors. In addition, the Lyapunov exponent of the map can achieve higher values, so the behavior of the proposed map is overall more complex compared to the original. The map is then successfully applied to the problem of random bit generation using techniques like the comparison between maps, XOR, and bit reversal. The proposed algorithm passes all the NIST tests, shows good correlation characteristics, and has a high key space. © 2020 by the authors

Use of Gd-doped ZnO surfaces to increase fluorescence of globular proteins

Novel ZnO - Gd3+ materials were prepared by sol-gel method and photoluminescence properties of their films were studied for biomedical application. Biosensor’s properties ZnO - Gd3+ films were investigated under the action of rabbit immunoglobulin G (IgG) in concentrations 10-9, 10-11 and 10-13 M in solution depositing on the surface of film. The doping of ZnO film by Gd3+ in an amount from 1-12 mass.% with increments of 1 mass. % results in significant variations of fluorescence spectra ZnO - Gd3+ films. The ZnO substrate without of Gd3+ compounds allows detecting IgG in a concentration of 10-11 M by fluorescence spectroscopy method by registration in UV region (320-450 nm). By using ZnO - Gd3+ system it was obtained the increase the concentration limit of immunoglobulin (10-13M) detection. In the only case (the content of Gd3+ in ZnO film - 8 mass. %) was observed batochromic shift of fluorescence band maximum by 20 nm (from 364 to 385nm) when interacting with immunoglobulin regardless of the concentration of the last. © 2018 TANGER Ltd. All Rights Reserved

Dependence of Gd-doped ZnO surfaces fluorescent properties on dopant concentration

Substrates containing zinc oxide and different amounts of gadolinium on the surface of the zinc oxide nano particles for biosensorics were obtained for the first time by the standard sol-gel technique. This is a new material has not yet been extensively studied. In this paper, we present the results of the photoluminescent response of the zinc oxide surface when it is modified by various amounts of gadolinium during the classical sol-gel method of the surface obtaining. Aspects of creating a modified surface of zinc oxide are highlighted. The used concentrations of gadolinium vary from 1 to 33% caused both quenching and ignition of photoluminescence at the wavelength of 356 nm upon excitation into the absorption band of protein 280 nm. The photoluminescence intensity of zinc oxide without doping is 40 relative value units, the addition of 8% Gd increases the photoluminescence by 7 times (280 r.u.), the addition of 31% Gd decreases the photoluminescence by 40 times compared to undoped zinc oxide. The resulting possibility of increased luminescence when the doping of the films with gadolinium willing, apparently, to increase the ratio “signal/background”, and therefore increase the sensitivity of the biosensor with fluorescent registration. © 2018 TANGER Ltd. All Rights Reserved

Recurrent supramolecular motifs in discrete complexes and coordination polymers based on mercury halides: Prevalence of chelate ring stacking and substituent effects

In recent years, the crystal engineering library has been enriched with a number of previously unrecognized or unnoticed intermolecular interactions, such as agostic, tetrel, chalcogen, pnicogen bonding and chelate ring stacking-collectively referred to as "unconventional interactions". Many open questions remain unaddressed regarding their ability to form synthon interactions, specificity, and cooperativity, for example with π-π stacking interactions. In this work, we throw light on the formation of chelate ring stacking in metal-organic assemblies of nicotinohydrazide ligands (N′-(1-(2-pyridyl)ethylidene)nicotinohydrazide (HL) and N′-(phenyl(pyridin-2-yl)methylene)nicotinohydrazide (HL1)) with mercury(ii) halide (HgBr2, HgI2) salts. Their reaction produced five compounds, namely [Hg(μ-L)BrHgBr2]n (1), [Hg(μ-L1)Br]n (2), [Hg(L)I2] (3), [Hg(HL1)I2]·(CH3OH) (4), and [Hg(μ-L1)I]n (5). Crystal structure analysis reveals that chelate ring stackings are formed in four of the reported metal-organic compounds, and are common also in the literature precedents. The energies of chelate ring stackings and π-π heterocycle stackings have been computed and analyzed by means of DFT calculations, and the results were verified using Bader's theory of "atoms in molecules". These results provide a rationale for preferential formation of both unconventional and conventional stackings and allow us to conclude that chelate ring interaction may be considered as a synthon interaction for nicotinohydrazide metal complexes. Interpretations for packing differences imposed by the substituent effect (substitution of methyl group in HL for phenyl group in HL1) were provided based on the Hirshfeld surface analysis and 2D fingerprint plots of the crystal structures reported here. © 2018 The Royal Society of Chemistry

Use of Gd-doped ZnO surfaces to increase fluorescence of globular proteins

Novel ZnO - Gd3+ materials were prepared by sol-gel method and photoluminescence properties of their films were studied for biomedical application. Biosensor’s properties ZnO - Gd3+ films were investigated under the action of rabbit immunoglobulin G (IgG) in concentrations 10-9, 10-11 and 10-13 M in solution depositing on the surface of film. The doping of ZnO film by Gd3+ in an amount from 1-12 mass.% with increments of 1 mass. % results in significant variations of fluorescence spectra ZnO - Gd3+ films. The ZnO substrate without of Gd3+ compounds allows detecting IgG in a concentration of 10-11 M by fluorescence spectroscopy method by registration in UV region (320-450 nm). By using ZnO - Gd3+ system it was obtained the increase the concentration limit of immunoglobulin (10-13M) detection. In the only case (the content of Gd3+ in ZnO film - 8 mass. %) was observed batochromic shift of fluorescence band maximum by 20 nm (from 364 to 385nm) when interacting with immunoglobulin regardless of the concentration of the last. © 2018 TANGER Ltd. All Rights Reserved

Optical properties of detonation nanodiamond complexes with globular proteins in water solution

It has been studied the changing of spectral characteristics of water-soluble 10 nm detonation nanodiamonds (DND) upon their complexation with a globular blood protein: bovine hemoglobin (Hb), human serum albumin (HSA) and rabbit immunoglobulin G (IgG) by fluorescence and absorption spectroscopy. The structure of the protein globule and its concentration in aqueous solution can significantly affect the complexation with DND (2·10-3 g/l) in the process of ultrasonic treatment (42 kHz). In all cases, it was observed when adding the DND the increasing of intensity of own luminescence of proteins (em = 330-346 nm) and bathochromic shift of protein luminescence bands. The magnitude of the shift of the maximum of protein luminescence bands at a protein concentration of 10-11 M was 5, 16, 18 nm, at the concentration 10-5 M - 7, 9, 2 nm for Hb, HSA and IgG, respectively. The aggregates’ size of DND was evaluated by AFM method in monocomponent film on the glass substrate. The results are of interest for investigations of the dynamic interaction of DND with biomacromolecules in vivo. © 2018 TANGER Ltd. All Rights Reserved