Mode Of Conjugation Research Articles

Experimental studies of sensors based on fiber Bragg gratings embedded in the internal structure of composite plates

The main purpose of this article is to study the structural characteristics of carbon fiber samples printed on a 3D printer, including embedded sensors, during 3D printing, through numerical and experimental studies. There is a widespread tendency to replace metals with modern composite materials. Various methods can be used to measure the destruction of the composite structure. Fiber Bragg array sensors are known as intelligent localized and global structural condition prediction devices for all kinds of structural applications, especially those using composite materials. In this work, we created control plates by impregnating a selected number of layers of carbon fabric with epoxy resin. Fiber-optic Bragg sensors were additionally located between the layers of carbon fabric. In the course of experimental studies, a fiber Bragg grating sensor was embedded in the middle of the sample, and a second sensor was attached to the finished surface of the sample. We conducted environmental tests to examine the durability of the additively manufactured standard’s components and the impact of integrated sensors on the composite sample. We applied the concept of equations, known as conjugate modes, and used the transition matrix method to solve them numerically. The scientific novelty of the work is the development of a new method and technology for measuring spatial deformation in composite materials using fiber-optic Bragg gratings.

Spherical nucleic acids for biomedical applications

Spherical nucleic acids (SNAs) are a 3D spherical nanostructure composed of highly oriented, dense layers of oligonucleotides conjugated to a hollow or solid core. This structure allows SNAs to show resistance to nuclease degradation, enter into nearly all cells without transfection agents and enable precise interactions with target molecules. Based on superior biological properties, SNAs can be tailored for diverse biological applications, rendering them a flexible and biosafe tool for biological applications as well as an enabling platform for therapy. In this review, we mainly discuss the structure and conjugation mode of SNAs and focus on recent advances in their applications, such as biomedical detection, imaging, and drug delivery. Finally, the remaining challenges and future directions of SNAs are also discussed and proposed.

Gelatin and lipidoid integrate to create gelasomes to enhance siRNA delivery with low toxicity

RNAi therapeutics possess the potential to cure many uncurable human diseases. For instance, RNAi therapeutics using liposomes showed remarkable survival benefits in patients with liver diseases. However, the extension of liposomes to deliver RNA to cure other ailments has largely been unsuccessful. Therefore, researchers are focusing on designing and testing different combinations of materials for versatile RNA delivery applications. Yet, an efficient and safe RNA delivery platform has not been identified. In this work, we have developed a new class of RNA-delivery vehicle called “Gelasomes,” using an incongruous combination of gelatin and lipidoid to exploit each material's unique properties while overcoming their inherent limitations. The low in vivo toxicity of Gelasomes is attributed to the exterior gelatin layers that shield the exposure of cationic lipidoid-siRNA clusters and yet present a biocompatible surface. Indeed, toxicity studies in mice indicate that repeated administration of Gelasomes (up to 48 mg/kg BW) is well-tolerated with no notable changes in body weight, hematology, or serum chemistry. Interestingly, the gelatin outer layer efficiently protects siRNA from serum degradation (48 h), preserving its functionality beyond two months of storage. Notably, Gelasomes possess dual siRNA conjugation modes, i.e., electrostatic binding with lipidoid core and covalent attachment to gelatin surface. The bivalency coupled with lipidoids' high transfection efficiency rendered Gelasomes with remarkably high gene silencing efficiency (>90 %) at very low treatment doses in vitro (40 μg/mL). In vivo studies further confirmed the high gene silencing ability of Gelasomes in non-small cell lung tumor mouse models. This new platform is tunable on all fronts: size, degree of surface coating, and biomolecule functionalization. Truncating the lipidoid C14-tail to a C8-tail yielded Gelasomes of reduced size. As lipidoids with different carbon lengths are synthesizable, we can develop a library of Gelasomes with different sizes. The surface coating with less gelatin resulted in high transfection efficiency at low doses of Gelasomes. The structure of Gelasomes offers chemical handles to couple target-specific molecules like antibodies to tune their properties for efficient biological application.

Nonlinear resonant responses of a novel FGM sandwich cylindrical shell structure for supersonic flight vehicles based on 1:1 internal resonance between conjugate modes

A new design scheme for the functionally graded material (FGM) sandwich cylindrical shell structure made of ceramic-FGM-carbon fiber composites is proposed, which is geared towards supersonic flight vehicles and has high specific stiffness and high-temperature resistance. We focus on analyzing the nonlinear resonant responses of the novel FGM sandwich cylindrical shell subjected to external excitation and aerodynamic force. Firstly, the mechanical properties of the novel FGM sandwich material are calculated, and then the nonlinear dynamic model of the FGM sandwich cylindrical shell is established based on the first order shear deformation theory (FSDT) and Hamilton's principle. Due to the axisymmetric property of the cylindrical shell, a 1:1 internal resonance between the driven and companion modes always exists in the perfect cylindrical shell. Taking this into consideration, the nonlinear resonant response problems of the FGM sandwich cylindrical shell are numerically simulated by combining the Galerkin method and the pseudo-arc length continuation method. Finally, the effects of complex parameters such as external excitation, aerodynamic force, aspect ratio, gradient index, and skin-core-skin ratio on the nonlinear resonant responses of the FGM sandwich cylindrical shell are investigated.

Bi-global stability of supersonic backward-facing step flow

Supersonic backward-facing step (BFS) flow is numerically studied using direct numerical simulation (DNS) and global stability analysis (GSA) with a free stream Mach number of 2.16 and a Reynolds number of 7.938 × 105 based on the flat-plate length L and free stream conditions. Two-dimensional BFS flow becomes unstable to three-dimensional perturbations as the step height h exceeds a certain value, while no two-dimensionally unstable mode is found. Global instability occurs with the fragmentation of the primary separation vortex downstream of the step. Two stationary modes and one oscillatory unstable mode are obtained at a supercritical ratio of L/h = 32.14, among which the two stationary modes originate from the coalescence of a pair of conjugate modes. The most unstable mode manifests itself as streamwise streaks in the reattached boundary layer, which is similar to that in shock-induced separated flow, although the flow separation mechanisms are different. Without introducing any external disturbances, the DNS captures the preferred perturbations and produces a growth rate in agreement with the GSA prediction in the linear growth stage. In the quasi-steady stage, the secondary separation vortex breaks up into several small bubbles, and the number of streamwise streaks is doubled. A low-frequency unsteadiness that may be associated with the oscillatory mode is also present.

How the Length of Through-Space Conjugation Influences the Clusteroluminescence of Oligo(Phenylene Methylene)s.

The length and mode of conjugation directly affect the molecular electronic structure, which has been extensively studied in through-bond conjugation (TBC) systems. Corresponding research greatly promotes the development of TBC-based luminophores. However, how the length and mode of through-space conjugation (TSC), one kind of weak interaction, influence the photophysical properties of non-conjugated luminophores remains a relatively unexplored field. Here, we unveil a non-linear relationship between TSC length and emission characteristics in non-conjugated systems, in contrast to the reported proportional correlation in TBC systems. More specifically, oligo(phenylene methylene)s (OPM[4]-OPM[7]) exhibit stronger TSC and prominent blue clusteroluminescence (CL) (≈440 nm) compared to shorter counterparts (OPM[2] and OPM[3]). OPM[6] demonstrates the highest solid-state quantum yield (40 %), emphasizing the importance of balancing flexibility and rigidity. Further theoretical calculations confirmed that CL of these oligo(phenylene methylene)s was determined by stable TSC derived from the inner rigid Diphenylmethane (DPM) segments within the oligomers instead of the outer ones. This discovery challenges previous assumptions and adds a new dimension to the understanding of TSC-based luminophores in non-conjugated systems.

How the Length of Through‐Space Conjugation Influences the Clusteroluminescence of Oligo(Phenylene Methylene)s

AbstractThe length and mode of conjugation directly affect the molecular electronic structure, which has been extensively studied in through‐bond conjugation (TBC) systems. Corresponding research greatly promotes the development of TBC‐based luminophores. However, how the length and mode of through‐space conjugation (TSC), one kind of weak interaction, influence the photophysical properties of non‐conjugated luminophores remains a relatively unexplored field. Here, we unveil a non‐linear relationship between TSC length and emission characteristics in non‐conjugated systems, in contrast to the reported proportional correlation in TBC systems. More specifically, oligo(phenylene methylene)s (OPM[4]‐OPM[7]) exhibit stronger TSC and prominent blue clusteroluminescence (CL) (≈440 nm) compared to shorter counterparts (OPM[2] and OPM[3]). OPM[6] demonstrates the highest solid‐state quantum yield (40 %), emphasizing the importance of balancing flexibility and rigidity. Further theoretical calculations confirmed that CL of these oligo(phenylene methylene)s was determined by stable TSC derived from the inner rigid Diphenylmethane (DPM) segments within the oligomers instead of the outer ones. This discovery challenges previous assumptions and adds a new dimension to the understanding of TSC‐based luminophores in non‐conjugated systems.

Nonlinear forced vibrations of functionally graded three-phase composite cylindrical shell subjected to aerodynamic forces, external excitations and hygrothermal environment

In this paper, the new functionally graded three-phase composite cylindrical shell is assumed as a common structure in the carrier rocket in the future, and we creatively study the nonlinear forced vibration of this cylindrical shell considering the interaction of different factors in the complex operating environment, including the aerodynamic forces, external excitations, and hygrothermal environment. Based on the first-order shear deformation theory, Von-Karman geometric nonlinear theory, and Hamilton's principle, we derive the nonlinear partial differential equations of motion of the functionally graded three-phase composite cylindrical shell. Considering the axisymmetry of the perfect circular shell, there is a 1:1 internal resonance between the conjugate modes of this cylindrical shell. On this basis, the nonlinear forced vibration of the cylindrical shell is investigated by a combination of Galerkin's method and the pseudo-arc length continuation method. Matcont toolbox can directly solve the ordinary differential equations to obtain the nonlinear frequency response curves. The method can effectively obtain both stable and unstable solutions, avoiding the mathematical difficulties encountered in the formulation process, and facilitating the study of the effects of parametric variables on the resonance response in complex environments. The results show that the variation of material parameters and the complex environment have important effects on the nonlinear resonance response of functionally graded three-phase composite cylindrical shell.

Whey Protein-Pectin Conjugate by Wet-Dry Heating: Optimization using Response Surface Methodology with Box-Behnken Design

The recent progress in glycation of proteins utilizing saccharides through the Maillard reaction has garnered substantial attention, with a specific emphasis on Whey Protein Concentrate (WPC). Conjugation mode is frequently intricate and poses challenges when scaling up for large-scale production. Consequently, this investigation sought to optimize the conditions of the WPC-pectin conjugation process using Response Surface Methodology (RSM) in conjunction with Box-Behnken design (BBD). The experimentation was executed employing a cabinet dryer, incorporating both wet and dry heating procedures to yield a WPC-pectin conjugate exhibiting favorable functional properties. The independent variables investigated encompassed pectin concentration (ranging from 0 to 1%), pH (ranging from 6 to 8), and drying time (ranging from 2 to 6 hours), The measured responses encompassed the emulsion stability index (ESI), emulsifying activity index (EAI), and solubility. Analyzing the experimental data underwent scrutiny for model sufficiency through diagnostic plots, and a second-order polynomial equation was fitted through multi-response regression analysis, resulting in a high coefficient of determination (R 2 ) value. The most effective parameters were identified as a pectin concentration of 0.49%, pH 6.7, and a drying duration of 4.12 hours, yielding a peak ESI of 452.267 minutes, EAI measuring 49.95 m 2 g -1 , and solubility reaching 48.09%. Further experiments were conducted to validate these outcomes, and the presence of the Maillard reaction was confirmed using Fourier Transform Infrared Spectrum (FTIR). The et-dry method demonstrated efficacy in producing WPCpectin conjugates with commendable functional properties.

Piezochromism and Conductivity Modulations under High Pressure by Manipulating the Viologen Radical Concentration.

Manipulating the radical concentration to modulate the properties in solid multifunctional materials is an attractive topic in various frontier fields. Viologens have the unique redox capability to generate radical states through reversible electron transfer (ET) under external stimuli. Herein, taking the viologens as the model, two kinds of crystalline compounds with different molecule-conjugated systems were designed and synthesized. By subjecting the specific model viologens to pressure, the cross-conjugated 2-X all exhibit much higher radical concentrations, along with more sensitive piezochromic behaviors, compared to the linear-conjugated 1-X. Unexpectedly, we find that the electrical resistance (R) of 1-NO3 decreased by three orders of magnitude with the increasing pressure, while that in high-radical-concentration 2-NO3 remained almost unchanged. To date, such unusual invariant conductivity has not been documented in molecular-based materials under high pressure, breaking the conventional wisdom that the generations of radicals are beneficial to improve conductivity. We highlight that adjusting the molecular conjugation modes can be used as an effective way to regulate the radical concentrations and thus modulate properties rationally.

Development of novel self-assembled vaccines based on tumour-specific antigenic peptide and TLR2 agonist for effective breast cancer immunotherapy via activating CD8+ T cells and enhancing their function.

Vaccines based on tumour-specific antigens are a promising approach for immunotherapy. However, the clinical efficacy of tumour-specific antigens is still challenging. Twelve conjugates with self-assembly properties were designed and synthesized using MAGE-A1 peptide and TLR2 agonist, combined with different covalent bonds. All the developed conjugates formed spherical nanoparticles with a diameter of approximately 150 nm, and enhanced the efficacy of the peptide vaccines with the better targeting of lymph nodes. All the conjugates could well bind to serum albumin and improve the plasma stability of the individual antigenic peptides. In particular, conjugate 6 (N-Ac PamCS-M-6) had a more significant ability to promote dendritic cell maturation, CD8+ T cell activation, and subsequent killing of tumour cells, with an in vivo tumour inhibition rate of 70 ± 2.9%. The interaction between specific response and the different conjugation modes was further explored, thereby providing a fundamental basis for novel immune anti-tumour molecular platforms.

Partition of topological indices of benzenoid hydrocarbons into ring contributions

AbstractThis work presents a simple method for partitioning the bond‐additive and atoms‐pair‐additive distance‐based topological indices of plane graphs into the sum of contributions of inner faces. The proposed method is applied to decompose several topological indices (Wiener, hyper‐Wiener, Tratch‐Stankevich‐Zefirov, Balaban, and Szeged indices) into the ring contributions for a series of benzenoid systems. It was found that the employed ring partitioning scheme is providing an accurate assessment of the dominant cyclic conjugation modes in the studied benzenoid hydrocarbons. Thus, the proposed method can be used as the alternative for the quantum‐chemistry‐based aromaticity indices which are significantly more computationally demanding.

Morphology, taxonomy and phylogenetic positions of two Spirogyra species (Zygnematophyceae, Streptophyta) with replicate and semi-replicate transverse walls from Japan

ABSTRACT Characteristics of transverse walls in filaments, and modes of conjugation are essential for species identification in the genus Spirogyra. Although most Spirogyra species have plane transverse walls, species with other types of transverse walls (replicate, semi-replicate and colligate types) have also been described. Recent molecular phylogenetic studies grouped species with replicate transverse walls in a single clade. However, phylogenetic positions of Spirogyra species with semi-replicate and colligate transverse walls have not yet been clarified. We examined vegetative and reproductive traits of two Spirogyra species with replicate and semi-replicate transverse walls collected in Japan, under culture conditions. One of them resembled most S. crassispina in having replicate transverse walls and both scalariform and lateral conjugation, with conjugation tubes separated from the filaments in lateral conjugation. However, these two species differed in their vegetative filaments, zygospores and mesospores; and the molecular phylogenetic analyses placed the Japanese strain with replicate transverse walls in a lineage separate from other previously known species with replicate transverse walls. Vegetative filaments of the other Japanese strain had semi-replicate transverse walls resembling those of previously known species S. unduliseptum and S. narcissiana. This strain differs from S. unduliseptum by the variation in zygospore ornamentation and from S. narcissiana by the presence of three types of conjugation; and it formed an independent lineage that was phylogenetically separated from two Spirogyra lineages characterized by having replicate transverse walls. The two Japanese strains reported on are described herein as S. minuticrassispina sp. nov. and S. tertia sp. nov.

Furthering extraction of torsional–flexural frequencies for thin-wall beams from the rocking motion of a two-wheel test vehicle

This paper proposes a furthering approach for extracting the first several flexural and torsional–flexural frequencies of thin-walled box girders from the residual contact response of a two-wheel test vehicle passing the bridge. Unlike most previous studies, the single-axle test vehicle is modeled as a two degree-of-freedom (DOF) system to account for the two wheels’ rocking motion, which relates to torsional–flexural motion of the beam. To start, a new theory for the mono-symmetric thin-walled beam subjected to a two-wheel moving vehicle is presented. The wheel contact response derived herein (which is free of vehicle frequencies) enables us in the first stance to remove the overshadowing effect on bridge frequencies brought by outstanding vehicle frequencies. The other concern in extracting the bridge frequencies is the noises posed by random pavement roughness, which is overcome through the use of the residual contact response generated by two identical connected vehicles. This paper furthers the existing ones in that the wheel response (i.e. the vehicle’s rocking motion) is utilized to extract the torsional–flexural frequencies of the bridge, making use of the linking action between the vehicle’s two wheels and the bridge’s cross section. The reliability of the theory and proposed technique is numerically validated for parameters such as damping of the vehicle and bridge, bridge/vehicle mass and frequency ratios, pavement roughness, and vehicle speed. It was confirmed that the proposed technique is capable of extracting the first several flexural and torsional–flexural frequencies of the thin-walled beam, including some higher conjugate modes, for all the cases studied herein.

Designing Functional Bionanoconstructs for Effective In Vivo Targeting.

The progress achieved over the last three decades in the field of bioconjugation has enabled the preparation of sophisticated nanomaterial–biomolecule conjugates, referred to herein as bionanoconstructs, for a multitude of applications including biosensing, diagnostics, and therapeutics. However, the development of bionanoconstructs for the active targeting of cells and cellular compartments, both in vitro and in vivo, is challenged by the lack of understanding of the mechanisms governing nanoscale recognition. In this review, we highlight fundamental obstacles in designing a successful bionanoconstruct, considering findings in the field of bionanointeractions. We argue that the biological recognition of bionanoconstructs is modulated not only by their molecular composition but also by the collective architecture presented upon their surface, and we discuss fundamental aspects of this surface architecture that are central to successful recognition, such as the mode of biomolecule conjugation and nanomaterial passivation. We also emphasize the need for thorough characterization of engineered bionanoconstructs and highlight the significance of population heterogeneity, which too presents a significant challenge in the interpretation of in vitro and in vivo results. Consideration of such issues together will better define the arena in which bioconjugation, in the future, will deliver functional and clinically relevant bionanoconstructs.

Structural guidelines for stabilization of α-helical coiled coils via PEG stapling.

Macrocyclization or stapling is one of the most well-known and generally applicable strategies for enhancing peptide/protein conformational stability and target binding affinity. However, there are limited structure- or sequence-based guidelines for the incorporation of optimal interhelical staples within coiled coils: the location and length of an interhelical staple is either arbitrarily chosen or requires significant optimization. Here we explore the impact of interhelical PEG stapling on the conformational stability and proteolytic resistance of a model disulfide-bound heterodimeric coiled coil. We demonstrate that (1) interhelical PEG staples are more stabilizing when placed farther from an existing disulfide crosslink; (2) e/g′ staples are more stabilizing than f/b′ or b/c′ staples; (3) PEG staples between different positions have different optimal staple lengths; (4) PEG stapling tolerates variation in the structure of the PEG linker and in the mode of conjugation; and (5) the guidelines developed here enable the rational design of a stabilized PEG-stapled HER-2 affibody with enhanced conformational stability and proteolytic resistance.

Second-order statistical properties of conjugate mode "double-H" partially coherent beams in turbulence.

We present an analysis of the propagation properties of a recently introduced class of conjugate mode partially coherent beams (called "double-H" beams) in a turbulent atmosphere using the extended Huygens-Fresnel integral. We investigate how the phase constant φ0 between the modes plays a role in controlling the evolution of the intensity distribution and resisting the degradation effects of the atmosphere. Our results indicate that this new class of structured beams provides a new degree of freedom for controlling the shape of the beams and improves turbulence resistance, with potential application in free-space optical communications.

Determination of the influence of a filler on the properties of composite materials based on polytetrafluorothylene for tribosystems of mechanisms and machines

This paper reports a comprehensive laboratory study into the thermophysical, physical-mechanical characteristics, and tribological properties of the designed composite materials based on polytetrafluoroethylene. In the structures of machines and mechanisms, a significant role belongs to the tribological conjugations made from polymeric and polymer-composite materials. The reliability of machines, in general, depends to a large extent on the reliability of movable connections. Composite materials of nonmetallic origin have a low cost, they are resistant to most aggressive chemicals and are capable of operating under conditions without lubrication. It was established that the characteristics and properties of materials must be adapted to the working conditions of separately considered tribological conjugations. The mechanisms of thermal destruction have been established, both in the basic material and the carbon fiber based on it. It was found that carbon fiber, regardless of its content (quantity) in the polymer-composite material based on polytetrafluoroethylene, is mainly oriented perpendicular to the force application plane. It was found that with an increase in the carbon fiber content from 10 to 40 % by weight, the heat capacity decreases by 16‒39 % compared to the main material. The optimal operating modes for the designed composite materials have been substantiated on the basis of a pv factor: under a dry friction mode – up to 4 MPa∙m/s; at friction with lubrication – up to 36.4 MPa∙m/s. The dependence has been established of the friction coefficient on the operating modes of a composite material based on polytetrafluoroethylene containing 20 % by weight of carbon fiber when lubricated with oil and water. The results reported here make it possible to synthesize the physical-mechanical characteristics and tribological properties of composite materials in accordance with the required modes of tribological conjugation.

Structure-Activity Relationships of Triple-Action Platinum(IV) Prodrugs with Albumin-Binding Properties and Immunomodulating Ligands.

Chemotherapy with platinum complexes is essential for clinical anticancer therapy. However, due to side effects and drug resistance, further drug improvement is urgently needed. Herein, we report on triple-action platinum(IV) prodrugs, which, in addition to tumor targeting via maleimide-mediated albumin binding, release the immunomodulatory ligand 1-methyl-d-tryptophan (1-MDT). Unexpectedly, structure–activity relationship analysis showed that the mode of 1-MDT conjugation distinctly impacts the reducibility and thus activation of the prodrugs. This in turn affected ligand release, pharmacokinetic properties, efficiency of immunomodulation, and the anticancer activity in vitro and in a mouse model in vivo. Moreover, we could demonstrate that the design of albumin-targeted multi-modal prodrugs using platinum(IV) is a promising strategy to enhance the cellular uptake of bioactive ligands with low cell permeability (1-MDT) and to improve their selective delivery into the malignant tissue. This will allow tumor-specific anticancer therapy supported by a favorably tuned immune microenvironment.

Crystal Structures of Tetramesityl‐Substituted Tetracyclopenta[def,jkl,pqr,vwx]tetraphenylene

AbstractCrystal structures of tetramesityl‐substituted tetracyclopenta[def,jkl,pqr,vwx]tetraphenylene (TCPTP) derivative were determined for crystals containing different solvents, CHCl3, CH2Cl2, acetone, and benzene at different temperatures to discuss the conjugation modes in the antiaromatic system, i. e., whether it adopts a D2h structure consisting of local aromatic sextets and quinodimethane substructures or a D4h double annulenenoid structure. The structures of the TCPTP core in all crystals determined at 113 K or 93 K resemble those of the theoretical D2h geometry, whereas the bond lengths at room temperature (293 K) adopt averaged values of the theoretical D2h and D4h geometries. These results are interpreted in terms of disorder of two perpendicularly oriented D2h structures at room temperature and support the theoretical prediction which favours the D2h geometry. The slightly different bond length distributions in the crystals are ascribed to the different space in the vicinity of the molecule which allows the molecule to adopt the two orientations in different occupancies.