Chain Interactions Research Articles

Single-Chain Mechanical Properties of Gelatin: A Single-Molecule Study.

Gelatin is an important natural biological resource with a wide range of applications in the pharmaceutical, industrial and food industries. We investigated the single-chain behaviors of gelatin by atomic force microscopy (AFM)-based single-molecule force spectroscopy (SMFS), and found that gelatin exists as long chains by fitting with the M-FJC model. By comparing the single-chain elasticity in a nonpolar organic solvent (nonane) and DI water, it was surprising to find that there was almost no difference in the single-chain elasticity of gelatin in nonane and DI water. Considering the specificity of gelatin solubility and the solvent size effect of nonane molecules, when a single gelatin chain is pulled into loose nonane, dehydration does not occur due to strong binding water interactions. Gelatin chains can only interact with water molecules at high temperatures; therefore, no further interaction of single gelatin chains with water molecules occurred at the experimental temperature. This eventually led to almost no difference in the single-chain F–E curves under the two conditions. It is expected that our study will enable the deep exploration of the interaction between water molecules and gelatin and provide a theoretical basis and experimental foundation for the design of gelatin-based materials with more functionalities.

Intermolecular CH-π Electrons Interaction in Poly (9,9-dioctylfluorenyl-2,7-diyl) (PFO): An Experimental and Theoretical Study.

This study demonstrates the presence of CH-π interaction in poly [9,9-dioctylfluorenyl-2,7-diyl] (PFO-1) due to an aggregate formation of PFO-1 in the liquid state. The absorption spectra of PFO-1 in certain solvents at low concentrations showed a single band at 390 nm. However, when using high concentrations, a new band at 437 nm appeared. This band is due to the aggregate formation of PFO-1. The aggregate formation occurs as a result of the CH interaction of the n-alkyl side chains with π-electrons in the benzene ring. The optical characteristics of another conjugated polymer of poly [9,9-di-(2-ethylhexyl)-fluorenyl-2,7-diyl] (PFO-2) were investigated to confirm the CH-π interaction. The absorption showed only one wavelength at 390 nm without any new band at the end of the spectrum, even at higher concentrations and lower temperatures. The main reason for the absence of aggregate formation in PFO-2 is the sterical hindrance caused by the branched alkyl side chains. In addition, Density Functional Theory (DFT) was used to compute the HOMO–LUMO transitions, electron charge distribution, and frontier molecular orbitals for each polymer. The Mulliken charge distribution and demonstrated a notable difference in the reactivity of the alkyl side chain, confirming the higher ability of PFO-1 to form CH-π bonds. docking model emphasized that the band at 437 nm could be attributed to the interaction between CH in the n-alkyl side chain and π bonds in the aromatic rings of PFO-1.

Analysis of Ethylene Copolymers with Long-Chain α-Olefins (1-Dodecene, 1-Tetradecene, 1-Hexadecene): A Transition between Main Chain Crystallization and Side Chain Crystallization.

A series of ethylene copolymers with long-chain α-olefins [LCAOs, 1-dodecene (DD), 1-tetradecene (TD), 1-hexadecene (HD)] and various LCAO contents were prepared, and their thermal properties, including effects of LCAO content and side chain length, were explored. The Cp*TiCl2(O-2,6-iPr2-4-SiEt3-C6H2)–MAO catalyst system afforded rather high-molecular-weight copolymers with unimodal molecular weight distributions and uniform compositions (confirmed by DSC thermograms). In addition to the melting temperatures (Tm values) corresponding to the so-called main chain crystallization (samples with low LCAO contents, the Tm value decreased upon increasing the LCAO content) and the side chain crystallization [polymer samples with high LCAO contents, by intermolecular interaction of side chains as observed in poly(DD), poly(TD), and poly(HD)], the other Tm value was observed, especially in poly(ethylene-co-HD)s (assumed to be due to co-crystallization of the branch and the main chain through an interaction of the main chain and the long side chains). The presence of another crystalline phase in poly(ethylene-co-HD)s was also suggested by a wide-angle X-ray diffraction (WAXD) analysis. These Tm values in poly(ethylene-co-TD)s and poly(ethylene-co-DD)s with rather high TD or DD contents were affected by the heating conditions in the measurement of DSC thermograms (5 or 10 °C/min), suggesting that the driving force for formation of the crystal packing (observed as Tm) is weak and affected by the alkyl side chain lengths.

A Hybrid Recommendation System Based on the Supply Chain in Social Networks

With the expansion of virtual social networks, finding and recommending appropriate and favorite information and items to users is one of the severe issues in their development. To this end, recommender systems predict and recommend interests based on past behavior reviews and user preferences. However, less research has been done on people to people in social networks, and it is still based on exploring communication and friendship circles, which is generally not desirable for specialized users. Social networks include a variety of entities such as individuals, businesses, companies, and technical communications that also contain a variety of information related to the supply chain interaction, such as industries, functions, and communications between them and users. This paper provides a recommendation system framework for recommending people to people in social networks based on supply chain interactions. For this purpose, it has presented five hybrid methods based on artificial neural networks and fuzzy strategies to provide better and more accurate recommendations than basic methods. Eventually, a case study was conducted on the LinkedIn social network to show the improvements in applying this new approach to primary methods. In this regard, seven specific evaluation criteria of recommender systems have been used.

Flexibly Controlling the Polycrystallinity and Improving the Foaming Behavior of Polylactic Acid via Three Strategies.

Controlling foamability plays the central role in preparing PLA foams with high performances. To achieve this, chain extension was often used to improve the rheological property of PLA resins; however, despite the availability of this approach, it often deteriorates the biodegradability of PLA and greatly increases the processing cost and complexity. Hence, we reported a special crystallization induction method to design PLA foams with a tunable cellular structure and a high expansion ratio. A novel crystallization-promoting agent combination (D-sorbitol, CO2, and phenylphosphonic acid zinc salt) was used to induce PLA to enhance the chain interaction force and chain mobility and to provide crystallization templets. A series of PLAs with tunable stereocomplex (Sc)/α crystallinity and rapid non-isothermal crystallization ability were obtained. The effect of various crystallization properties on the foaming behavior of PLA was studied. The results demonstrated that proper crystallization conditions (a small spherulite size, a crystallinity of 6%, and rapid crystallization ability) could virtually contribute to the optimized cellular structure with the highest cell density of 4.36 × 106 cell/cm3. When the Sc crystallinity was above 10%, PLA had a superior foamability, which thereby resulted in a high foaming expansion ratio of 16.2. A variety of cellular morphologies of PLA foams could be obtained by changing the foaming temperature and the crystallization property. The proposed crystallization-induced approach provided a useful method for controlling the cellular structure and the performances of the PLA foams.

Paramagnetic relaxation enhancement NMR reveals the structures and ribosome interactions of nascent chains during biosynthesis

The crucial process of protein folding begins co-translationally on the ribosome. Emerging evidence is demonstrating that the ribosome itself is an active player in regulating the folding of nascent chains, a process that is vital for proteostasis. However, surprisingly little is known structurally about the conformations of nascent polypeptides on their parent ribosome during vectorial emergence and how the ribosome modulates co-translational folding.

Effect of point mutations on the network of side chain interactions of prion protein fibrils with distinct quaternary structures

Prion diseases are fatal neurodegenerative disorders that occur in mammals, including humans. At the molecular level, prion diseases are characterized by the presence of prion aggregates that are fibrillar and b-sheet rich. Intriguingly, prion protein fibrils display multiple morphologies, each characterized by unique biochemical properties and linked to distinct disease phenotypes. Few quaternary structures of prion protein fibrils from mice have been proposed based on cryoEM studies. However, the extent to which those structures represent fibrils formed by the prion protein of differentially disease-susceptible species remains unresolved.

Side chain interactions in C-terminal S4 helix required for gating polarity of HCN channels

Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels contribute to the rhythmic firing of pacemaker neurons and cardiomyocytes. Mutations in HCN channels are associated with cardiac arrhythmia and epilepsy. HCN channels belong to the superfamily of voltage-gated K+ channels, most of which are activated by depolarizations. HCN channels, however, stand out in this family because they are activated by hyperpolarizations. The reversed gating polarity of HCN channels is attributed to a different coupling between the voltage-sensing domain (VSD) and the pore domain (PD).

Intrinsically Viscoelastic Supramolecular Conjugated Polymer toward Suppressing Coffee-Ring Effect

Intrinsically Viscoelastic Supramolecular Conjugated Polymer toward Suppressing Coffee-Ring Effect

Influences of NaCl and Na2SO4 on the Micellization Behavior of the Mixture of Cetylpyridinium Chloride + Polyvinyl Pyrrolidone at Several Temperatures.

Herein, the conductivity measurement technique is used to determine the interactions that may occur between polyvinyl pyrrolidone (PVP) polymer and cetylpyridinium chloride (CPC) surfactant in the presence of NaCl and Na2SO4 of fixed concentration at variable temperatures (298.15–323.15 K) with an interval of 5 K. In the absence or presence of salts, we observed three critical micelle concentrations (CMC) for the CPC + PVP mixture. In all situations, CMC1 values of CPC + PVP system were found to be higher in water than in attendance of salts (NaCl and Na2SO4). Temperature and additives have the tendency to affect counterion binding values. Various physico-chemical parameters were analyzed and demonstrated smoothly, including free energy (ΔG0m), enthalpy (ΔH0m) and entropy change (ΔS0m). The micellization process is achieved to be spontaneous based on the obtained negative ΔG0m values. The linearity of the and values is excellent. The intrinsic enthalpy gain (ΔH0*m) and compensation temperature (Tc) were calculated and discussed with logical points. Interactions of polymer hydrophobic chains or the polymer + surfactant associated with amphiphilic surface-active drugs can employ a strong impact on the behavior of the gels.

Chain Stiffness of Donor–Acceptor Conjugated Polymers in Solution

The optoelectronic properties of conjugated polymers are dictated by their chain conformations, which depend on the interplay of delocalization of electrons along the π-conjugated backbone and the intrachain interactions of pendant side chains. Here, we leverage small-angle neutron scattering to measure the chain shapes of several classes of commonly used, high mobility donor–acceptor conjugated polymers in dilute solution. We find that these model conjugated polymers are semiflexible with persistence lengths ranging from several to hundreds of nanometers, dependent on the molecular structure of the polymer, indicating the importance of repeat unit geometry, particularly side-chain size and branching, on the overall chain conformations. The measured persistence lengths show good agreement with those calculated according to dihedral distributions predicted from density functional theory. Larger persistence lengths are shown to correlate with increased charge-carrier mobility, signifying the importance of rational molecular design to obtain high persistence length organic semiconductors and thus advantageous optoelectronic properties.

СУЧАСНІ МЕТОДИ ОПТИМІЗАЦІЇ УПРАВЛІННЯ ЛАНЦЮГАМИ ПОСТАЧАННЯ НА ЗАСАДАХ СТАЛОГО РОЗВИТКУ

Limited access to resources, significant deterioration of the climate and increased influence of natural disasters, social problems and poverty – these are the global problems that require decisive action in all areas of the economy. These issues make the strategy of sustainable development more relevant than ever, which determines the goals of this study. The purpose of the article is to analyze the features and prospects of improving modern methods of supply chain management based on sustainable development. Green logistics reviewed as the system of modern improvement trends of resource flow management, its key advantages, stages and reasons for development are described. The impact of modern market requirements and sustainable development goals on the tasks of logistics is evaluated: changes in the goals of reducing the overall level of costs and creating additional value for the consumer are described in the article. The main areas of improvement of green logistics are systematized according to their sphere of influence. Such organizational methods of improving logistics as Lean Production, standardization, integration and changes in legislation have a significant impact on how planning and interaction in supply chains works, these improvements contribute to the active involvement of labor resources in the implementation of sustainable development. Technological methods for improving green logistics rely heavily on digitization, automation, and robotization of many processes; artificial intelligence technology has great prospects for forecasting and modeling, which allows to reduce operational costs of logistics. The electrification of transport, the transition to ecological materials and alternative energy, which contributes to the development of circular supply chains, are also relevant directions of development. Conclusions are made regarding the significant prospects for the development of supply chains on the basis of sustainable development and the practical possibilities of upgrading logistics in the future, such as: reducing polluting and carbon footprint, reducing total costs and creating additional value, improving level of the competitiveness, are evaluated.

Valence-controlled protein conjugation on nanoparticles via re-arrangeable multivalent interactions of tandem repeat protein chains.

Precise control of the number of conjugated proteins on a nanoparticle surface has long been a highly challenging task. Here, we developed a one-pot, purification-free strategy for valency-controlled conjugation of tandem repeat protein chains on gold nanoparticles. Protein chains were designed to contain multiple, regularly spaced binding modules, which can multivalently interact with coating molecules on nanoparticle surfaces. We discovered that a slow increase of this interaction strength facilitates full participation of repeated binding modules on a protein chain for surface binding (as well as dynamic rearrangement) on a single nanoparticle, which resulted in stable protein chain wrapping around nanoparticles. By varying the protein chain length, a defined number of protein chains were conjugated on gold nanoparticles with difference sizes. Various high-order nanoparticle structures were accurately assembled with these valence-controlled protein–particle conjugates. The present strategy offers a highly dynamic but controlled protein coating approach on solid surfaces of diverse nanostructures. In addition, this work also provides a valuable clue to understand dynamic binding processes of multivalent repeat proteins.

Towards a universal manufacturing node: Requirements for a versatile, laser-based machine tool for highly adaptable manufacturing

The current trend in the context of Industry 4.0 towards small batch sizes and increasing product variety results in ever-changing requirements for both, the products and the production. This requires highly versatile, fully and easily adaptable, and efficient manufacturing environments that can meet these demands, ideally already on the level of the machine tool. Because of its versatility, the laser is a promising tool for such a machine tool, but there is still a considerable need for research in the field of system technology.We consider the requirements for a versatile, laser-based machine tool for highly adaptable manufacturing, that utilizes the combination of laser-based manufacturing processes on one machine. The focus of the considerations lies on remote processes and the processing of metals. Five key research topics for the development of such a universal laser manufacturing node are identified: highly dynamic and precise kinematics (1); ‘on-the-fly’ reconfigurable, distributed control architectures (2); adaptable process diagnostics for online quality monitoring (3); technological interactions in laser-based process chains (4); and models for a fast estimation of the process parameters for each production step (5). The relevance and current needs for research for each topic are discussed and corresponding solution concepts are proposed.

Hopf Bifurcation for Detritus Food Chain in Mangrove Ecosystem

We proposed a prey-predator model portraying interaction in Detritus food chains. The primary view of this paper is to describe the interaction in the Detritus food chain due to the presence of a predator in mangrove ecosystems. Predation by assuming that the predator takes more time to eat its prey. We analyze the local stability of the equilibria point. Numerical simulations are achieved to clarify the theoretical result and display the change in the equilibria point solution through a bifurcation diagram. The numerical continuity of carrying capacity parameters in the system solution indicated the presence of the Hopf Bifurcation.

Compositionally Driven Viscometric Behaviors of Poly (Alkyl Methacrylates) in Lubricating Oils

Viscosity index (VI) and shear stability index (SSI) are standard methods used in the lubricant industry to determine temperature-viscosity dependency and resistance to product degradation, respectively. A variety of oil-soluble polymers, including poly(alkyl methacrylates) (PAMAs) are routinely used to control these properties in fully-formulated liquid lubricants. In this report, we use reversible addition-fragmentation chain transfer (RAFT) polymerization to precisely target identical degrees of polymerization in a family of PAMAs with varying lauryl, hexyl, butyl, ethyl, and methyl groups. Then, expanding on previous methodology reported in the literature, we establish structure property relationships for these PAMAs, specifically looking at how intrinsic viscosity [η] and Martin interaction parameters KM relate to VI and SSI characteristics. While the intrinsic viscosity [η] is associated with the volume of macromolecules at infinite dilution, the parameter KM reflects the hydrodynamic interactions of polymer chains at actual polymer concentrations in lubricating oils. In this paper, we show that the dependence of VI on the non-dimensional concentration c/c* (or c[η]) can be presented in a form of master curve with shift factors proportional to KM that decreases with increasing size of alkyl groups. This finding implies that even in the dilute regime, the coil-expansion theory used to explain the effect of macromolecules on VI should be complemented with the idea of hydrodynamic interactions between polymer molecules that can be controlled by the choice of alkyl chains in the family of PAMAs.

PEGDA hydrogel structure from semi-dilute concentrations: insights from experiments and molecular simulations.

The efficacy of hydrogel materials used in biomedical applications is dependent on polymer network topology and the structure of water-laden pore space. Hydrogel microstructure can be tuned by adjusting synthesis parameters such as macromer molar mass and concentration. Moreover, hydrogels beyond dilute conditions are needed to produce mechanically robust and dense networks for tissue engineering and/or drug delivery systems. Thus, this study utilizes a combined experimental and molecular simulation approach to characterize structural features for 4.8 and 10 kDa poly (ethylene glycol) diacrylate (PEGDA) hydrogels formed from a range of semi-dilute solution concentrations. The connection between chain-chain interactions in polymer solutions, hydrogel structure, and equilibrium swelling behavior is presented. Bulk rheology analysis revealed an entanglement concentration for PEGDA pre-gel solutions around 28 wt% for both macromers studied. A similar transition in swelling behavior was revealed around the same concentration where hydrogel capacity to retain water was drastically reduced. To understand this transition, the hydrogel structure was characterized using the swollen polymer network hypothesis and compared to pore size distributions from molecular dynamics simulations. We find in both approaches a structural transition concentration at the hydrogel swelling inflection point that is comparable to the entanglement concentration. Calculated mesh sizes from theory are compared with computationally determined average maximum pore diameters; mesh sizes from theory yielded greater feature sizes across all concentrations considered. Molecular simulations are further used to assess pore dynamics, which are shown to vary in distribution shape and number of modes compared to the time-averaged hydrogel pore features. Altogether, this work provides insights into hydrogel network features and their dynamic behavior at physiological conditions (37 °C) as a basis for hydrogel design beyond dilute conditions for biomedical applications.

Understanding structural variability in proteins using protein structural networks.

Proteins perform their function by accessing a suitable conformer from the ensemble of available conformations. The conformational diversity of a chosen protein structure can be obtained by experimental methods under different conditions. A key issue is the accurate comparison of different conformations. A gold standard used for such a comparison is the root mean square deviation (RMSD) between the two structures. While extensive refinements of RMSD evaluation at the backbone level are available, a comprehensive framework including the side chain interaction is not well understood. Here we employ protein structure network (PSN) formalism, with the non-covalent interactions of side chain, explicitly treated. The PSNs thus constructed are compared through graph spectral method, which provides a comparison at the local and at the global structural level. In this work, PSNs of multiple crystal conformers of single-chain, single-domain proteins, are subject to pair-wise analysis to examine the dissimilarity in their network topologies and in order to determine the conformational diversity of their native structures. This information is utilized to classify the structural domains of proteins into different categories. It is observed that proteins typically tend to retain structure and interactions at the backbone level. However, some of them also depict variability in either their overall structure or only in their inter-residue connectivity at the sidechain level, or both. Variability of sub-networks based on solvent accessibility and secondary structure is studied. The types of specific interactions are found to contribute differently to structure variability. An ensemble analysis by computing the mathematical variance of edge-weights across multiple conformers provided information on the contribution to overall variability from each edge of the PSN. Interactions that are highly variable are identified and their impact on structure variability has been discussed with the help of a case study. The classification based on the present side-chain network-based studies provides a framework to correlate the structure-function relationships in protein structures.

Organic amendments for crop production, phosphorus bioavailability and heavy metal immobilisation: a review

Repeated and excessive use of inorganic phosphorus fertilisers adversely affects soil fertility, reduces plant phosphorus (P)-use efficiency, increases soil heavy metal concentrations and poses human health risks via food chain interaction. Organic amendments (OAs) are considered as cost-effective and environment-friendly supplement to inorganic P fertilisers that are produced from scarce phosphate rocks. Numerous studies have reported the synergistic and antagonistic effects of OAs on crop production, P solubility and availability, and immobilisation of heavy metals. However, the results of these studies are found to be variable and demand a critical review. This article summarises the environmental and health implications of continuous inorganic P fertilisers application along with a detailed overview of commonly available OAs and their efficacy to stimulate plant growth and yield. Moreover, this review describes the potentiality of OAs to increase the bioavailability of P in soil, discusses how and to what extent these soil amendments can immobilise heavy metals and reduce plant uptake, and finally provides future research directions for organic farming and sustainable agricultural practices.

Digital Twin for Inventory Planning of Fresh Produce

The management of perishable food inventory demands special attention. Fruits quickly lose their freshness and perish if they are not consumed within a specified period. It is critical to develop a management tool based on the Internet of Things that can efficiently integrate all the dynamic data associated with various types of resources in real-time along the supply chain. This research is part of a comprehensive supply chain framework developed to analyze food bank logistics supply chain interactions. The study will mainly focus on the use of historical time-series data to create a digital twin that can anticipate future events. The digital twin framework was built based on the operational trend of the Italian food bank to strengthen the decision support system related to the fresh food inventory. The SAP Analytics Cloud was used to create a solution that would help the organization better satisfy consumer needs by reducing fruit waste in the inventory.