Surface Of Helix Research Articles

Barrel rifling node offset detection and subsequent optimization based on thin film in-mold decoration characteristics of the Johnson–Cook model

In this paper, a nodal detection method for the detection and optimization of barrel helix offsets is proposed. The barrel used in this experiment is a 6-helix barrel. Moreover, the special properties of the film of Polyetheretherketone (PEEK) material are used to cover the surface of the barrel helix with a virtual in-mold decoration (IMD) film, and the unique nature of the film die offset in the IMD is utilized to detect the position of the barrel helix. The area with a large die index is the area with a large helix offset in the barrel, and the IMD die index is introduced to quantify the data. The IMD die index is used to determine the helix offset of the damaged barrel. The novelty of this work is that each node can use the die index to efficiently detect the position of the barrel helix deviation, carry out subsequent optimization and repair work through the optimization of the injection molding parameters and the design optimization of the barrel and verify the experiment by comparing the results. Through the steady-state simulation research mode, different permutations and combinations of the two process parameters are simulated to study their effects. Quantitative reference indicators include but are not limited to dependent variables such as the fluid flow velocity, shear rate, temperature distribution and phase transition, and the shear heating process of the injection screw is taken into account in the mold flow analysis to ensure that the die index value is more accurate. It can be seen from the analysis results that the temperature of the barrel changes after the groove depth and groove width are changed, and the effect ratio of the groove depth is lower than that of the groove width in the same degree of size change.

A molecular synergy of non-covalent interactions facilitated via theobromine modifying the self-assembly process of type I collagen

Type I Collagen is a multifunctional fibrous protein present significantly in the connective tissues. Generally, fibril formation process of an interstitial collagen begins with a triple helix alignment to form a pentafibril, which sequentially self-assembles into a microfibril. Typically, this sequential formation can be achieved under an in vitro condition as well by maintaining certain specific physiological parameters to mimic the interstitial microenvironment of collagen. The necessity to study such a kinetically driven process is due to its implications in template fabrication particularly as a scaffold to enhance the growth of specific stem cells or accelerating nanoparticle synthesis. Drawing inspiration from this, theobromine, a methylxanthine that contributes towards the hydrogen bond network via dimerization and stacking interaction was used as a small molecule in modifying the molecular level interactions of a self-assembled collagen. Initially, rheological studies revealed certain variations in the viscous properties of collagen on addition of theobromine. Turbidity assay showed an increase in the rate of fibril formation and its topographical changes were observed through the high-resolution scanning electron microscope. The stability and probable physico-chemical interactions between collagen and theobromine were comprehended from the vibrational frequency changes recorded using (FT-IR) (ATR) and conformational changes using Circular Dichroism (CD) studies. Our results show possible multibinding sites on theobromine, which would compete to bind with the polar and non-polar residues exposed over the monomeric surfaces of triple helix causing a local conformational fluctuation modifying protein-protein interaction.

A Property that Characterizes the Enneper Surface and Helix Surfaces

The main goal of this paper is to show that helix surfaces and the Enneper surface are the only surfaces in the 3-dimensional Euclidean space R3\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\mathbb {R}^{3}$$\\end{document} whose isogonal lines are generalized helices and pseudo-geodesic lines.

Studies on meshing clearance of thread pairs of planetary roller screw mechanism in different directions

The helix surface model of planetary roller screw mechanism (PRSM) is established by utilizing the parametric equations of space surface according to the structural features of screw, roller and nut. The helix surface model of PRSM is improved in consideration of the PRSM assembly relationship. The normal vector equations of helix surfaces are obtained based on the helix surface model. The meshing clearance models of PRSM in axial, radial and circumferential directions are built considering the movement direction of parts utilizing surface meshing conditions. The influence of structural parameters on the meshing clearance of PRSM is also analyzed. The results show that the meshing points between the roller and the screw in three directions are not in the middle diameter. The meshing points in the three directions of the roller and the nut are in the middle diameter of the roller. The pitch, tooth angle and tooth thickness of the thread all have an influence on the meshing clearance of PRSM. Only by increasing the tooth thickness of the thread can the meshing clearance in the three directions be reduced at the same time. The pitch and tooth angle should be selected properly to meet the practical requirements.

Helix surfaces for Berger-like metrics on the anti-de Sitter space

We consider the Anti-de Sitter space H13\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\mathbb {H}^3_1$$\\end{document} equipped with Berger-like metrics, that deform the standard metric of H13\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\\mathbb {H}^3_1$$\\end{document} in the direction of the hyperbolic Hopf vector field. Helix surfaces are the ones forming a constant angle with such vector field. After proving that these surfaces have (any) constant Gaussian curvature, we achieve their explicit local description in terms of a one-parameter family of isometries of the space and some suitable curves. These curves turn out to be general helices, which meet at a constant angle the fibers of the hyperbolic Hopf fibration.

Interface-Based Design of High-Affinity Affibody Ligands for the Purification of RBD from Spike Proteins.

The outbreak of coronavirus disease 2019 (COVID-19) has sparked an urgent demand for advanced diagnosis and vaccination worldwide. The discovery of high-affinity ligands is of great significance for vaccine and diagnostic reagent manufacturing. Targeting the receptor binding domain (RBD) from the spike protein of severe acute respiratory syndrome-coronavirus 2, an interface at the outer surface of helices on the Z domain from protein A was introduced to construct a virtual library for the screening of ZRBD affibody ligands. Molecular docking was performed using HADDOCK software, and three potential ZRBD affibodies, ZRBD-02, ZRBD-04, and ZRBD-07, were obtained. Molecular dynamics (MD) simulation verified that the binding of ZRBD affibodies to RBD was driven by electrostatic interactions. Per-residue free energy decomposition analysis further substantiated that four residues with negative-charge characteristics on helix α1 of the Z domain participated in this process. Binding affinity analysis by microscale thermophoresis showed that ZRBD affibodies had high affinity for RBD binding, and the lowest dissociation constant was 36.3 nmol/L for ZRBD-07 among the three potential ZRBD affibodies. Herein, ZRBD-02 and ZRBD-07 affibodies were selected for chromatographic verifications after being coupled to thiol-activated Sepharose 6 Fast Flow (SepFF) gel. Chromatographic experiments showed that RBD could bind on both ZRBD SepFF gels and was eluted by 0.1 mol/L NaOH. Moreover, the ZRBD-07 SepFF gel had a higher affinity for RBD. This research provided a new idea for the design of affibody ligands and validated the potential of affibody ligands in the application of RBD purification from complex feedstock.

Structural insight into an anti-BRIL Fab as a G-protein-coupled receptor crystallization chaperone.

Structure determination of G-protein-coupled receptors (GPCRs) is key for thesuccessful development of efficient drugs targeting GPCRs. BRIL is a thermostabilized apocytochrome b562 (with M7W/H102I/R106L mutations) from Escherichia coli and is often used as a GPCR fusion protein for expression and crystallization. SRP2070Fab, an anti-BRIL antibody Fab fragment, has been reported to facilitate and enhance the crystallization of BRIL-fused GPCRs as a crystallization chaperone. This study was conducted to characterize the high-resolution crystal structure of the BRIL-SRP2070Fab complex. The structure of the BRIL-SRP2070Fab complex was determined at 2.1 Å resolution. This high-resolution structure elucidates the binding interaction between BRIL and SRP2070Fab. When binding to BRIL, SRP2070Fab recognizes conformational epitopes, not linear epitopes, on the surface of BRIL helices III and IV, thereby binding perpendicularly to the helices, which indicates stable binding. Additionally, the packing contacts of the BRIL-SRP2070Fab co-crystal are largely due to SRP2070Fab rather than BRIL. The accumulation of SRP2070Fab molecules by stacking is remarkable and is consistent with the finding that stacking of SRP2070Fab is predominant in known crystal structures of BRIL-fused GPCRs complexed with SRP2070Fab. These findings clarified the mechanism of SRP2070Fab as a crystallization chaperone. Moreover, these data will be useful in the structure-based drug design of membrane-protein drug targets.

Engineering Chiral Induction in Centrally Functionalized o-Phenylenes.

Work on foldamers, nonbiological oligomers that mimic the hierarchical structure of biomacromolecules, continues to yield new architectures of ever increasing complexity. o-Phenylenes, a class of helical aromatic foldamers, are well-suited to this area because of their structural simplicity and the straightforward characterization of their folding in solution. However, control of structure requires, by definition, control over folding handedness. Control over o-phenylene twist sense is currently lacking. While chiral induction from groups at o-phenylene termini has been demonstrated, it would be useful to instead direct twisting from internal positions to leave the ends free. Here, we explore chiral induction in a series of o-phenylenes with chiral imides at their centers. Conformational behavior has been studied by nuclear magnetic resonance and circular dichroism spectroscopies and density functional theory calculations. Chiral induction in otherwise unfunctionalized o-phenylenes is generally poor. However, strategic functionalization of the helix surface with trifluoromethyl or methyl groups allows it to better interact with the imide groups, greatly increasing diastereomeric excesses. The sense of chiral induction is consistent with computational models that suggest that it primarily arises from a steric effect.

A Uniquely Stable Trimeric Model of SARS-CoV-2 Spike Transmembrane Domain.

Understanding fusion mechanisms employed by SARS-CoV-2 spike protein entails realistic transmembrane domain (TMD) models, while no reliable approaches towards predicting the 3D structure of transmembrane (TM) trimers exist. Here, we propose a comprehensive computational framework to model the spike TMD only based on its primary structure. We performed amino acid sequence pattern matching and compared the molecular hydrophobicity potential (MHP) distribution on the helix surface against TM homotrimers with known 3D structures and selected an appropriate template for homology modeling. We then iteratively built a model of spike TMD, adjusting “dynamic MHP portraits” and residue variability motifs. The stability of this model, with and without palmitoyl modifications downstream of the TMD, and several alternative configurations (including a recent NMR structure), was tested in all-atom molecular dynamics simulations in a POPC bilayer mimicking the viral envelope. Our model demonstrated unique stability under the conditions applied and conforms to known basic principles of TM helix packing. The original computational framework looks promising and could potentially be employed in the construction of 3D models of TM trimers for a wide range of membrane proteins.

A High “Steaks” Molecular Story: Copper Interactions with Mad Cow Disease Prion Proteins

Transmissible spongiform encephalopathies (TSEs), better known as prion diseases, are a group of progressive neurodegenerative diseases that affect both animals and humans. The most well‐known example, bovine spongiform encephalopathy (BSE), better known as “mad cow disease,” is a progressive neurological disorder of cattle that is created as a result of a mutation in the cellular prion protein (PrPc) into a toxic isoform called PrP scrapie (PrPSc). This disease first gained public attention when a British outbreak affected about 180,000 cattle between 1986 and 2001, devastating numerous agricultural communities. The Independent School BioClub SMART Team used 3‐D modeling and printing technology to examine PrPc and PrPSc molecular structures, focusing specifically on the protein’s metal‐binding properties. Copper (II) ion (Cu2+), PrPc’s highest affinity metal ion, plays a significant role in the interdomain interaction between the globular C‐terminal domain, consisting of three □‐helices and one short □‐sheet, and the flexible N‐terminal domain. Cu2+ ion binds to the PrPc N‐terminal octarepeat domain (OR), which is considered fundamental due to its series of four (or more) tandem repeats. Each tandem repeat can bind one Cu2+ ion, which directly interacts with a specific highly conserved, negatively‐charged region of the globular domain defined by the exposed surface of helices 2 and 3. The N‐terminal domain of PrPc causes severe neurotoxicity unless the globular domain properly regulates it. In humans, this prion protein mutation leads to Creutzfeldt‐Jakob disease (CJD), which has the same neurodegenerative symptoms as BSE. A negatively‐charged region on the surface of helix 3 occupied by the Cu2+ ion also overlaps with the epitopes of many PrPc antibodies associated with prion diseases. A better understanding of these interactions could potentially lead to discovering a cure for neurodegenerative diseases caused by PrPc’s misfolded form, such as CJD and Alzheimer’s.

A point-contact conjugate hourglass worm drive based on the meshing theory of conjugate tooth surfaces generated by two generating surfaces

To solve the problems of narrow contact area and small contact ratio of the involute cylindrical worm helical gear drive, this paper proposed a point-contact conjugate hourglass worm drive (PCHW drive) based on the meshing theory of conjugate tooth surfaces generated by two generating surfaces. The hourglass worm and worm gear are generated by the helix surface of an involute helical gear and that of an involute cylindrical worm. A mathematical model of the drive is established and a method for solving contact points based on involute pitch point is given. The instantaneous transmission ratio is proved theoretically to be constant and transmission error is zero. The formation mechanism of the conjugate surfaces of the drive is revealed. The results of the tooth contact analysis for a numerical example show that he contact area of this drive is wider, the contact ratio is slightly increased compared to the involute cylindrical worm helical gear drive. Furthermore, the drive is insensitive to manufacturing and assembly errors. A prototype is manufactured and meshing test is performed to verify the theoretical correctness.

Design of Oligourea-Based Foldamers with Antibacterial and Antifungal Activities.

There is an urgent need to develop new therapeutic strategies to fight the emergence of multidrug resistant bacteria. Many antimicrobial peptides (AMPs) have been identified and characterized, but clinical translation has been limited partly due to their structural instability and degradability in physiological environments. The use of unnatural backbones leading to foldamers can generate peptidomimetics with improved properties and conformational stability. We recently reported the successful design of urea-based eukaryotic cell-penetrating foldamers (CPFs). Since cell-penetrating peptides and AMPs generally share many common features, we prepared new sequences derived from CPFs by varying the distribution of histidine- and arginine-type residues at the surface of the oligourea helix, and evaluated their activity on both Gram-positive and Gram-negative bacteria as well as on fungi. In addition, we prepared and tested new amphiphilic block cofoldamers consisting of an oligourea and a peptide segment whereby polar and charged residues are located in the peptide segment and more hydrophobic residues in the oligourea segment. Several foldamer sequences were found to display potent antibacterial activities even in the presence of 50% serum. Importantly, we show that these urea-based foldamers also possess promising antifungal properties.

Rational design of a helical peptide inhibitor targeting c-Myb\u2013KIX interaction

The transcription factor c-Myb promotes the proliferation of hematopoietic cells by interacting with the KIX domain of CREB-binding protein; however, its aberrant expression causes leukemia. Therefore, inhibitors of the c-Myb–KIX interaction are potentially useful as antitumor drugs. Since the intrinsically disordered transactivation domain (TAD) of c-Myb binds KIX via a conformational selection mechanism where helix formation precedes binding, stabilizing the helical structure of c-Myb TAD is expected to increase the KIX-binding affinity. Here, to develop an inhibitor of the c-Myb–KIX interaction, we designed mutants of the c-Myb TAD peptide fragment where the helical structure is stabilized, based on theoretical predictions using AGADIR. Three of the four initially designed peptides each had a different Lys-to-Arg substitution on the helix surface opposite the KIX-binding interface. Furthermore, the triple mutant with three Lys-to-Arg substitutions, named RRR, showed a high helical propensity and achieved three-fold higher affinity to KIX than the wild-type TAD with a dissociation constant of 80 nM. Moreover, the RRR inhibitor efficiently competed out the c-Myb–KIX interaction. These results suggest that stabilizing the helical structure based on theoretical predictions, especially by conservative Lys-to-Arg substitutions, is a simple and useful strategy for designing helical peptide inhibitors of protein–protein interactions.

Chirality Induction to CdSe Nanocrystals Self-Organized on Silica Nanohelices: Tuning Chiroptical Properties.

CdSe nanocrystals (NCs) were grafted on chiral silica nanoribbons, and the mechanism of resulting chirality induction was investigated. Because of their chiral organization, these NCs show optically active properties that depend strongly on their grafting densities and sizes of the NCs. The effect of the morphology of the chiral silica templates between helical (cylindrical curvature) vs twisted (saddle like curvature) ribbons was investigated. The g-factor of NCs-silica helical ribbons is larger than that of the NCs-silica twisted ribbons. Finally, rod-like NCs (QR) with different lengths were grafted on the twisted silica ribbons. Interestingly, their grafting direction with respect to the helix surface changed from side-grafting for short QR to tip-grafting for long rods and the corresponding CD spectra switched signs.

ИНТЕНСИВНЫЙ ЭНЕРГОСБЕРЕГАЮЩИЙ МЕТОД СУШКИ ЗЕРНА

The method of drying of grain and removal of moisture which is based on receiving and processing of arising thermal processes described by the thermodynamics equation is developed. This way was a little studied and was less often applied because of considerable imperfection of the production technology of the converter of frequency of big power (to some hundred kilowatts) and frequencies (to some hundred kHz). However, at present the equipment for induction heating gained big development and its application on drying installations in comparison with traditional ways of heating more preferably. Offered induction way of drying of grain where the grain material passes through drying mine by gravity. For carrying out pilot studies, it is developed the transistor–thyristor device, which consists of the control unit, the converter of frequency, the bunker with the screw in it that has helix surface, inductor windings, and a hydrometer. The algorithm of receiving and data processing is developed in the MATLAB software. At further increase in frequency the coefficient of losses won't change, therefore, considering that our device works in GHz range coefficient of losses will be constant, i.e. equal 0,6. Therefore when studying influence of humidity of grain on coefficient of losses we can consider with confidence that frequency doesn't influence the accuracy of measurements. The amount of heat received by moisture in a weevil increases with increase in its humidity. It is a first time when the Maxwell’s formula is suitable for calculating a heat taken from grain moisture. Reduction in specific cost of all plants demands the appeal to development and introduction simple on a design of induction heaters that is an actual problem. Agricultural production, unlike other types of production, possesses a considerable resource – the reserved energy in a biological object. Thus, use of information approach to the description of reactions of biological objects on external influence allows to develop electrotechnologies for increase of productivity, productivity of the grain drying equipment, decrease in power consumption of process of drying of grain.

APPLICATION OF RULED SURFACES IN FREEFORM AND GEAR METROLOGY

An application of two ruled surfaces (i.e., surfaces generated by a motion of a straight line), a surface of hyperbolic paraboloid and a tangent surface of a cylindrical helix in freeform and gear metrology is introduced in this paper. Both surfaces have been implemented as the main functional figures in several artefacts – metrological calibration standards intended for testing the freeform capabilities of various measuring technologies (e.g., tactile point-to-point measurement and tactile scanning on coordinate measuring machine, optical scanning, computer tomography). Geometrical and mathematical properties of the surface used are summarised, CAD models of all the developed standards are presented and photos of the manufactured standards are shown.

ИНТЕНСИВНЫЙ ЭНЕРГОСБЕРЕГАЮЩИЙ МЕТОД СУШКИ ЗЕРНА

The method of drying of grain and removal of moisture which is based on receiving and processing of arising thermal processes described by the thermodynamics equation is developed. This way was a little studied and was less often applied because of considerable imperfection of the production technology of the converter of frequency of big power (to some hundred kilowatts) and frequencies (to some hundred kHz). However, at present the equipment for induction heating gained big development and its application on drying installations in comparison with traditional ways of heating more preferably. Offered induction way of drying of grain where the grain material passes through drying mine by gravity. For carrying out pilot studies, it is developed the transistor–thyristor device, which consists of the control unit, the converter of frequency, the bunker with the screw in it that has helix surface, inductor windings, and a hydrometer. The algorithm of receiving and data processing is developed in the MATLAB software. At further increase in frequency the coefficient of losses won't change, therefore, considering that our device works in GHz range coefficient of losses will be constant, i.e. equal 0,6. Therefore when studying influence of humidity of grain on coefficient of losses we can consider with confidence that frequency doesn't influence the accuracy of measurements. The amount of heat received by moisture in a weevil increases with increase in its humidity. It is a first time when the Maxwell’s formula is suitable for calculating a heat taken from grain moisture. Reduction in specific cost of all plants demands the appeal to development and introduction simple on a design of induction heaters that is an actual problem. Agricultural production, unlike other types of production, possesses a considerable resource – the reserved energy in a biological object. Thus, use of information approach to the description of reactions of biological objects on external influence allows to develop electrotechnologies for increase of productivity, productivity of the grain drying equipment, decrease in power consumption of process of drying of grain.

Residue-by-residue analysis of cotranslational membrane protein integration in vivo.

We follow the cotranslational biosynthesis of three multispanning Escherichia coli inner membrane proteins in vivo using high-resolution force profile analysis. The force profiles show that the nascent chain is subjected to rapidly varying pulling forces during translation and reveal unexpected complexities in the membrane integration process. We find that an N-terminal cytoplasmic domain can fold in the ribosome exit tunnel before membrane integration starts, that charged residues and membrane-interacting segments such as re-entrant loops and surface helices flanking a transmembrane helix (TMH) can advance or delay membrane integration, and that point mutations in an upstream TMH can affect the pulling forces generated by downstream TMHs in a highly position-dependent manner, suggestive of residue-specific interactions between TMHs during the integration process. Our results support the 'sliding' model of translocon-mediated membrane protein integration, in which hydrophobic segments are continually exposed to the lipid bilayer during their passage through the SecYEG translocon.

Nanotubular Oxide Layer Formed on Helix Surfaces of Dental Screw Implants

Surface modification is used to extend the life of implants. To increase the corrosion resistance and improve the biocompatibility of metal implant materials, oxidation of the Ti-13Nb-13Zr titanium alloy was used. The samples used for the research had the shape of a helix with a metric thread, with their geometry imitating a dental implant. The oxide layer was produced by a standard electrochemical method in an environment of 1M H3PO4 + 0.3% HF for 20 min, at a constant voltage of 30 V. The oxidized samples were analyzed with a scanning electron microscope. Nanotubular oxide layers with internal diameters of 30–80 nm were found. An analysis of the surface topography was performed using an optical microscope, and the Sa parameter was determined for the top of the helix and for the bottom, where a significant difference in value was observed. The presence of the modification layer, visible at the bottom of the helix, was confirmed by analyzing the sample cross-sections using computed tomography. Corrosion tests performed in the artificial saliva solution demonstrated higher corrosion current and less noble corrosion potential due to incomplete surface coverage and pitting. Necessary improved oxidation parameters will be applied in future work.

Yoğunluklu Öklidyen 3-Uzayında Helis Yüzeyleri

The differential geometry of helix curves and helix hypersurfaces in different spaces has important application areas in many disciplines. Also, the notion of weighted manifold is become to be a very popular topic for scientists in recent years. In this context, after defining the notions of weighted mean curvature (or φ-mean curvature) and weighted Gaussian curvature (or φ-Gaussian curvature) of an n-dimensional hypersurface on manifolds with density, lots of studies have been done by differential geometers in different spaces with different densities. So, in the present study, firstly we give the normal vector field, mean curvature and Gaussian curvature of a helix surface in three dimensional Euclidean space and after that, we obtain the weighted mean curvature and weighted Gaussian curvature of a helix surface generated by a unit speed planar curve in three dimensional Euclidean space with different three densities by stating the parametric equation of this surface. However, we know that a hypersurface is weighted minimal and weighted flat in Eucilidean 3-space with density if the weighted mean curvature and the weighted Gaussian curvature vanish, respectively. So, by using these definitions, we obtain the weighted minimal helix surfaces for these different densities and give some results for weighted flatness of the helix surfaces in Euclidean 3-space. We hope that, this study will bring a new viewpoint to differential geometers who are dealing with constant angle surfaces and in near future, one can handle these surfaces in different spaces with another densities.