A novel MADM algorithm for physical education teaching quality evaluation based on 2-tuple linguistic neutrosophic numbers power heronian mean operators.

Classroom teaching quality evaluation is an important link in the curriculum quality assurance system. It has important guiding significance for the timely feedback of classroom teaching effects, the achievement of teachers' teaching goals, and the implementation of teaching plans. The evaluation system is scientific, objective and accurate. The classroom teaching quality evaluation is an important way to improve the level of teacher education and teaching and then determine the quality of talent training in various majors. At present, although the evaluation work has played a positive role, the backwardness of the evaluation system has seriously restricted the effectiveness of teaching feedback. The classroom teaching quality evaluation of college basketball training is viewed as the multi-attribute decision-making (MADM). In this article, we combine the generalized Heronian mean (GHM) operator and power average (PA) with 2-tuple linguistic neutrosophic sets (2TLNSs) to propose the generalized 2-tuple linguistic neutrosophic power HM (G2TLNPHM) operator. The G2TLNPHM operator is built for MADM. Finally, an example for classroom teaching quality evaluation of college basketball training is used to show the proposed methods.

Probing Molecular Interactions between Surface-Immobilized Antimicrobial Peptides and Lipopolysaccharides In Situ.

Lipopolysaccharide (LPS) is a component of the outer membrane of Gram-negative bacteria. Recently, a label-free immobilized antimicrobial peptide (AMP) surface plasmon resonance platform was developed to successfully distinguish LPS from multiple bacterial strains. Among the tested AMPs, SMAP29 exhibited excellent affinity with LPS and has two independent LPS-binding sites located at two termini of the peptide. In this study, sum frequency generation vibrational spectroscopy was applied to investigate molecular interactions between three LPS samples and surface-immobilized SMAP29 via the N-terminus, the C-terminus, and a middle site at the solid/liquid interface in situ in real-time, supplemented by circular dichroism spectroscopy. It was found that the conformations and orientations of surface-immobilized SMAP29 via different sites are different when interacting with the same LPS, with different interaction kinetics. The same SMAP29 sample also has different structures and interaction kinetics while interacting with different LPS samples with different charge densities and hydrophobicities. The observed results on molecular interactions between surface-immobilized peptides and LPS can well interpret the different adsorption amounts of various LPSs on different surface-immobilized peptides.

Molecular Mechanisms of Interactions between Monolayered Transition Metal Dichalcogenides and Biological Molecules.

Single layered two-dimensional (2D) materials such as transition metal dichalcogenides (TMDs) show great potential in many microelectronic or nanoelectronic applications. For example, because of extremely high sensitivity, TMD-based biosensors have become promising candidates for next-generation label-free detection. However, very few studies have been conducted on understanding the fundamental interactions between TMDs and other molecules including biological molecules, making the rational design of TMD-based sensors (including biosensors) difficult. This study focuses on the investigations of the fundamental interactions between proteins and two widely researched single-layered TMDs, MoS2, and WS2 using a combined study with linear vibrational spectroscopy attenuated total reflectance FTIR and nonlinear vibrational spectroscopy sum frequency generation vibrational spectroscopy, supplemented by molecular dynamics simulations. It was concluded that a large surface hydrophobic region in a relatively flat location on the protein surface is required for the protein to adsorb onto a monolayered MoS2 or WS2 surface with preferred orientation. No disulfide bond formation between cysteine groups on the protein and MoS2 or WS2 was found. The conclusions are general and can be used as guiding principles to engineer proteins to attach to TMDs. The approach adopted here is also applicable to study interactions between other 2D materials and biomolecules.

Chemically Immobilized Antimicrobial Peptide on Polymer and Self-Assembled Monolayer Substrates.

Surfaces with chemically immobilized antimicrobial peptides have been shown to have great potential in various applications such as biosensors and antimicrobial coatings. This research investigated the chemical immobilization of a cecropin-melittin hybrid antimicrobial peptide on two different surfaces, a polymer surface prepared by chemical vapor deposition (CVD) polymerization and a self-assembled monolayer surface. We probed the structure of immobilized peptides using spectroscopic methods and correlated such structural information to the measured antimicrobial activity. We found that the hybrid peptide adopts an α-helical structure after immobilization onto both surfaces. As we have shown previously for another α-helical peptide, MSI-78, immobilized on a SAM, we found that the α-helical hybrid peptide lies down when it contacts bacteria. This study shows that the antimicrobial activity of the surface-immobilized peptides on the two substrates can be well explained by the spectroscopically measured peptide structural data. In addition, it was found that the polymer-based antimicrobial peptide coating is more stable. This is likely due to the fact that the SAM prepared using silane may be degraded after several days whereas the polymer prepared by CVD polymerization is more stable than the SAM, leading to a more stable antimicrobial coating.

Structures and Adhesion Properties at Polyethylene/Silica and Polyethylene/Nylon Interfaces.

The molecular structures of buried interfaces of maleic anhydride grafted and ungrafted polyethylene films with silica and nylon surfaces were studied in situ using sum-frequency generation (SFG) vibrational spectroscopy. Grafting maleic anhydride to polyethylene altered the molecular structures at buried interfaces, including changing the orientation of polymer methylene groups and resulting in the presence of C═O groups at silica interfaces. These molecular level changes are correlated with enhanced adhesion properties, with ordered C═O groups and in-plane orientation of the methylene groups associated with higher levels of adhesion. While improved adhesion was observed for grafted polyethylene at the nylon interface, no C═O groups were detected at the interface using SFG, for films thermally treated at 185 °C. In this case, either no C═O groups are present at the interface or they are disordered; the latter explanation is more likely, considering the observed improvement in adhesion.

Molecular interactions between single layered MoS2 and biological molecules.

Two-dimensional (2D) materials such as graphene, molybdenum disulfide (MoS2), tungsten diselenide (WSe2), and black phosphorous are being developed for sensing applications with excellent selectivity and high sensitivity. In such applications, 2D materials extensively interact with various analytes including biological molecules. Understanding the interfacial molecular interactions of 2D materials with various targets becomes increasingly important for the progression of better-performing 2D-material based sensors. In this research, molecular interactions between several de novo designed alpha-helical peptides and monolayer MoS2 have been studied. Molecular dynamics simulations were used to validate experimental data. The results suggest that, in contrast to peptide-graphene interactions, peptide aromatic residues do not interact strongly with the MoS2 surface. It is also found that charged amino acids are important for ensuring a standing-up pose for peptides interacting with MoS2. By performing site-specific mutations on the peptide, we could mediate the peptide-MoS2 interactions to control the peptide orientation on MoS2.

Monitoring Antimicrobial Mechanisms of Surface-Immobilized Peptides in Situ.

Antimicrobial peptides (AMPs) in free solution can kill bacteria by disrupting bacterial cell membranes. Their modes of action have been extensively studied, and various models ranging from pore formation to carpet-like mechanisms were proposed. Surface-immobilized AMPs have been used as coatings to kill bacteria and as sensors to capture bacteria, but the interaction mechanisms of surface-immobilized AMPs and bacteria are not fully understood. In this research, an analytical platform, sum frequency generation (SFG) microscope, which is composed of an SFG vibrational spectrometer and a fluorescence microscope, was used to probe molecular interactions between surface-immobilized AMPs and bacteria in situ in real time at the solid/liquid interface. SFG probed the molecular structure of surface-immobilized AMPs while interacting with bacteria, and fluorescence images of dead bacteria were monitored as a function of time during the peptide-bacteria interaction. It was believed that upon bacteria contact, the surface-immobilized peptides changed their orientation and killed bacteria. This research demonstrated that the SFG microscope platform can examine the structure and function (bacterial killing) at the same time in the same sample environment, providing in-depth understanding on the structure-activity relationships of surface-immobilized AMPs.

Effect of Interfacial Molecular Orientation on Power Conversion Efficiency of Perovskite Solar Cells.

A wide variety of charge carrier dynamics, such as transport, separation, and extraction, occur at the interfaces of planar heterojunction solar cells. Such factors can affect the overall device performance. Therefore, understanding the buried interfacial molecular structure in various devices and the correlation between interfacial structure and function has become increasingly important. Current characterization techniques for thin films such as X-ray diffraction, cross section scanning electronmicroscopy, and UV-visible absorption spectroscopy are unable to provide the needed molecular structural information at buried interfaces. In this study, by controlling the structure of the hole transport layer (HTL) in a perovskite solar cell and applying a surface/interface-sensitive nonlinear vibrational spectroscopic technique (sum frequency generation vibrational spectroscopy (SFG)), we successfully probed the molecular structure at the buried interface and correlated its structural characteristics to solar cell performance. Here, an edge-on (normal to the interface) polythiophene (PT) interfacial molecular orientation at the buried perovskite (photoactive layer)/PT (HTL) interface showed more than two times the power conversion efficiency (PCE) of a lying down (tangential) PT interfacial orientation. The difference in interfacial molecular structure was achieved by altering the alkyl side chain length of the PT derivatives, where PT with a shorter alkyl side chain showed an edge-on interfacial orientation with a higher PCE than that of PT with a longer alkyl side chain. With similar band gap alignment and bulk structure within the PT layer, it is believed that the interfacial molecular structural variation (i.e., the orientation difference) of the various PT derivatives is the underlying cause of the difference in perovskite solar cell PCE.

Molecular Interactions between Graphene and Biological Molecules.

Applications of graphene have extended into areas of nanobio-technology such as nanobio-medicine, nanobio-sensing, as well as nanoelectronics with biomolecules. These applications involve interactions between proteins, peptides, DNA, RNA etc. and graphene, therefore understanding such molecular interactions is essential. For example, many applications based on using graphene and peptides require peptides to interact with (e.g., noncovalently bind to) graphene at one end, while simultaneously exposing the other end to the surrounding medium (e.g., to detect analytes in solution). To control and characterize peptide behavior on a graphene surface in solution is difficult. Here we successfully probed the molecular interactions between two peptides (cecropin P1 and MSI-78(C1)) and graphene in situ and in real-time using sum frequency generation (SFG) vibrational spectroscopy and molecular dynamics (MD) simulation. We demonstrated that the distribution of various planar (including aromatic (Phe, Trp, Tyr, and His)/amide (Asn and Gln)/Guanidine (Arg)) side-chains and charged hydrophilic (such as Lys) side-chains in a peptide sequence determines the orientation of the peptide adsorbed on a graphene surface. It was found that peptide interactions with graphene depend on the competition between both planar and hydrophilic residues in the peptide. Our results indicated that part of cecropin P1 stands up on graphene due to an unbalanced distribution of planar and hydrophilic residues, whereas MSI-78(C1) lies down on graphene due to an even distribution of Phe residues and hydrophilic residues. With such knowledge, we could rationally design peptides with desired residues to manipulate peptide-graphene interactions, which allows peptides to adopt optimized structure and exhibit excellent activity for nanobio-technological applications. This research again demonstrates the power to combine SFG vibrational spectroscopy and MD simulation in studying interfacial biological molecules.

Influence of the side chain and substrate on polythiophene thin film surface, bulk, and buried interfacial structures.

The molecular structures of organic semiconducting thin films mediate the performance of various devices composed of such materials. To fully understand how the structures of organic semiconductors alter on substrates due to different polymer side chains and different interfacial interactions, thin films of two kinds of polythiophene derivatives with different side-chains, poly(3-hexylthiophene) (P3HT) and poly(3-potassium-6-hexanoate thiophene) (P3KHT), were deposited and compared on various surfaces. A combination of analytical tools was applied in this research: contact angle goniometry and X-ray photoelectron spectroscopy (XPS) were used to characterize substrate dielectric surfaces with varied hydrophobicity for polymer film deposition; X-ray diffraction and UV-vis spectroscopy were used to examine the polythiophene film bulk structure; sum frequency generation (SFG) vibrational spectroscopy was utilized to probe the molecular structures of polymer film surfaces in air and buried solid/solid interfaces. Both side-chain hydrophobicity and substrate hydrophobicity were found to mediate the crystallinity of the polythiophene film, as well as the orientation of the thiophene ring within the polymer backbone at the buried polymer/substrate interface and the polymer thin film surface in air. For the same type of polythiophene film deposited on different substrates, a more hydrophobic substrate surface induced thiophene ring alignment with the surface normal at both the buried interface and on the surface in air. For different films (P3HT vs. P3KHT) deposited on the same dielectric substrate, a more hydrophobic polythiophene side chain caused the thiophene ring to align more towards the surface at the buried polymer/substrate interface and on the surface in air. We believe that the polythiophene surface, bulk, and buried interfacial molecular structures all influence the hole mobility within the polythiophene film. Successful characterization of an organic conducting thin film surface, buried interfacial, and bulk structures is a first crucial step in understanding the structure-function relationship of such films in order to optimize device performance. An in-depth understanding on how the side-chain influences the interfacial and surface polymer orientation will guide the future molecular structure design of organic semiconductors.

Effect of Solvent on Surface Ordering of Poly(3-hexylthiophene) Thin Films.

Enhancement of charge transport in organic polymer semiconductors is a crucial step in developing optimized devices. A variety of sample preparation conditions, such as film fabrication method, solvent species, and annealing, were found to influence the hole mobility of organic polymers. Despite the fact that many factors can influence their performance, it is believed that polymer surface ordering plays a key role in determining organic polymer function. Here, sum frequency generation (SFG) vibrational spectroscopy was used to nondestructively map the surface/interfacial ordering of poly(3-hexylthiophene) (P3HT) films prepared using different solvents; we believe that solvent interactions determine the degree of surface/interfacial ordering. Both X-ray diffraction (XRD) spectroscopy and scanning electron microscopy (SEM) were used to supplement SFG to systematically study bulk crystallinity and surface morphology. We conclude that SFG is a powerful tool to elucidate the surface/interfacial structural information on polymer semiconducting films. We demonstrate that the solvent composition used to prepare P3HT thin films influences the resulting film surface morphology, surface/interfacial ordering, and bulk crystallinity.

Small circular DNA molecules act as rigid motifs to build DNA nanotubes.

Small circular DNA molecules with designed lengths, for example 64 and 96 nucleotides (nt), after hybridization with a few 32-nt staple strands respectively, can act as rigid motifs for the construction of DNA nanotubes with excellent uniformity in ring diameter. Unlike most native DNA nanotubes, which consist of longitudinal double helices, nanotubes assembled from circular DNAs are constructed from lateral double helices. Of the five types of DNA nanotubes designed here, four are built by alternating two different rings of the same ring size, while one is composed of all the same 96-nt rings. Nanotubes constructed from the same 96-nt rings are 10-100 times shorter than those constructed from two different 96-nt rings, because there are fewer hinge joints on the rings.