Attachment Mode Research Articles

A novel bonding strategy of hydrogel on titanium alloy for marine antifouling engineering: multiple antifouling mechanisms and DFT calculations

Marine biofouling is one of the biggest problems for titanium alloys and rutile TiO2 coatings in marine engineering applications. Hydrogel materials are a novel and environmentally benign antifouling strategy, but they cannot be stabilized on alloy surfaces to provide long-term protection. Focusing on the challenges of bonding at the hydrogel-alloy interface, a PAA/PHEMA composite hydrogel containing Cu2O@PEG powder was strongly bonded to the titanium alloy by forming chemical bonds with APTES. The composite hydrogel still achieves an adhesion strength of 60-70 kPa after 7 days of immersion. The samples maintained a stable copper ion leaching rate of 2.61~3.76μg·cm-2·d-1 after 21 days of immersion. The coating-modified titanium alloys showed a 100% bactericidal rate within three hours of contact with different bacteria and exhibited a high anti-algal adhesion rate of up to 99%. In addition, the attachment mode of APTES on rutile TiO2 was clarified for the first time by Density Functional Theory (DFT) calculations. According to DFT calculations, the adsorption energy of APTES on Ti-TiO2 is -747.025kJ/mol, and the adsorption energy of acrylic acid on TiO2-APTES is -535.152kJ/mol. The chemical bonding connection between the hydrogel-alloy interface, as a novel interface bonding strategy, would be expected to broaden the application of titanium alloy in marine engineering.

Wake Structures and Hydrodynamic Characteristics of Flows around Two Near-Wall Cylinders in Tandem and Parallel Arrangements

To clarify the hydrodynamic interference characteristics of flows around multiple cylinders under the wall effect, the two-dimensional (2D) flows around the near-wall single, two tandem and parallel cylinders are simulated under different gap ratios (0.15 ≤ G/D ≤ 3.0) and spacing ratios (1.5 ≤ T/D ≤ 4.0) at a Reynolds number of Re = 6300. We also examine the wake patterns, the force coefficients, and the vortex-shedding frequency with emphases on the wall effect and effects of the two-cylinder interference. A critical wall gap of G/D = 0.6 is identified in the single-cylinder case where the wall can exert significant influences. The two near-wall tandem cylinders exhibit three wake states: stretching mode, attachment mode, and impinging mode. The force coefficients on the upstream cylinder are significantly affected by the wall for G/D ≤ 0.6. The downstream cylinder is mainly influenced by the upstream cylinder. For G/D > 0.6, the force coefficients on the two cylinders exhibit a similar variation trend. In the parallel arrangement, the two cylinders exhibit four wake states in different G/D and T/D ranges: double stretching mode, hetero-vortex scale mode, unilateral vortex mode, and free vortex mode. Moreover, the two parallel cylinders in the hetero-vortex scale or free vortex mode have two states: synchronous in-phase state and synchronous out-of-phase state. The mean drag coefficients on the two cylinders decrease, while the mean lift coefficients exhibit opposite variation trends, as the T/D grows.

Modal Derivatives for Efficient Vibration Prediction of Geometrically Nonlinear Structures with Friction Contact

This paper evaluates the performance of the Rubin reduction methods, enhanced with static modal derivatives, for vibration analysis of geometrically nonlinear structures with friction contact. Static modal derivatives are computed numerically based on Rubin reduction, which includes free interface normal modes and residual flexibility attachment modes, by introducing a finite displacement around these modes. Then, the most relevant static modal derivatives are selected using an improved strategy that incorporates weighting factors derived from both a nonlinear static analysis and a geometrically linear transient run. This enhanced Rubin method is also compared with the previously used enhanced Craig–Bampton method, which is based on fixed normal modes, constraint modes, and their static derivatives. The effectiveness of these methods is demonstrated through vibration analysis of a geometrically nonlinear beam in different contact configurations. Both methods proved their robustness, achieving accurate results with a relatively small number of modes in the reduced space, thus ensuring low online computation times. Furthermore, the analyses show the significant impact of using a geometrically nonlinear model on the accurate prediction of a contact state.

Interspecific occupancy-abundance relationship of benthic diatoms changes seasonally with attachment mode in a tropical river

Interspecific occupancy-abundance relationship of benthic diatoms changes seasonally with attachment mode in a tropical river

Chemically Bonded Pepsin via Its Inert Center to Diazo Functionalized Silica Gel through Multipoint Attachment Mode: A Way of Restoring Biocatalytic Sustainability over "Wider pH" Range.

Proteolytic enzymes play a pivotal role in the industry. Still, because of denaturation, the extensive applicability at their level of best catalytic efficiency over a more comprehensive pH range, particularly in alkaline conditions over pH 8, has not been fully developed. On the other hand, enzyme immobilization following a suitable protocol is a long pending issue that determines the conformational stability, specificity, selectivity, enantioselectivity, and activity of the native enzymes at long-range pH. As a bridge between these two findings, in an attempt at a freezing temperature 273-278 K at an alkaline pH, the diazo-functionalized silica gel (SG) surface has been used to rapidly diazo couple pepsin through its inert center, the O-carbon of the phenolic -OH of surface-occupied Tyr residues in a multipoint mode: when all the various protein groups, viz., amino, thiol, phenol, imidazole, carboxy, etc., in the molecular sequence including those belonging to the active sites, remain intact, the inherent inbuilt interactions among themselves remain. Thereby, the macromolecule's global conformation and helicity preserve the status quo. The dimension of the SG-enzyme conjugate confirms as {Si(OSi)4 (H2O)1.03}n {-O-Si(CH3)2-O-C6H4-N═N+}4·{pepsin}·yH2O; where the values of n and y have been determined respectively as 347 and 188. The material performs the catalytic activity much better at 7-8.5 than at pH 2-3.5 and continues for up to six months without any appreciable change.

Characterization of a unique attachment organelle: Single-cell force spectroscopy of Giardia duodenalis trophozoites.

The unicellular parasite Giardia duodenalis is the causative agent of giardiasis, a gastrointestinal disease with global spread. In its trophozoite form, G. duodenalis can adhere to the human intestinal epithelium and a variety of other, artificial surfaces. Its attachment is facilitated by a unique microtubule-based attachment organelle, the so-called ventral disc. The mechanical function of the ventral disc, however, is still debated. Earlier studies postulated that a dynamic negative pressure under the ventral disc, generated by persistently beating flagella, mediates the attachment. Later studies suggested a suction model based on structural changes of the ventral discs, substrate clutching or grasping, or unspecific contact forces. In this study, we aim to contribute to the understanding of G. duodenalis attachment by investigating detachment characteristics and determining adhesion forces of single trophozoites on a smooth glass surface (RMS = 1.1 ± 0.2 nm) by fluidic force microscopy (FluidFM)-based single-cell force spectroscopy (SCFS). Briefly, viable adherent trophozoites were approached with a FluidFM micropipette, immobilized to the micropipette aperture by negative pressure, and detached from the surface by micropipette retraction while retract force curves were recorded. These force curves displayed novel and so far undescribed characteristics for a microorganism, namely, gradual force increase on the pulled trophozoite, with localization of adhesion force shortly before cell detachment length. Respective adhesion forces reached 7.7 ± 4.2 nN at 1 μm s-1 pulling speed. Importantly, this unique force pattern was different from that of other eukaryotic cells such as Candida albicans or oral keratinocytes, considered for comparison in this study. The latter both displayed a force pattern with force peaks of different values or force plateaus (for keratinocytes) indicative of breakage of molecular bonds of cell-anchored classes of adhesion molecules or membrane components. Furthermore, the attachment mode of G. duodenalis trophozoites was mechanically resilient to tensile forces, when the pulling speeds were raised up to 10 μm s-1 and adhesion forces increased to 28.7 ± 10.5 nN. Taken together, comparative SCSF revealed novel and unique retract force curve characteristics for attached G. duodenalis, suggesting a ligand-independent suction mechanism, that differ from those of other well described eukaryotes.

Nest attachment, rather than nest type, correlates with passerine bird brain size

Variation in relative interspecific brain size has been correlated with cognitive capacities in different animal groups. Bird nest construction is one of the most remarkable animal abilities, and has reached the highest diversification in the Passeriformes. Yet, its relationship with brain size is not fully understood. Here, we used a dataset of 455 species to address potential correlations between nest types (open and enclosed) and five categories of nest attachment mode, as well as a set of covariables, with relative brain mass (Rbmass) of passerine birds. Bayesian regression modelling with phylogenetic control revealed that nest attachment mode, rather than nest type, was associated with Rbmass variation, despite the strong effects of habitat, migration and phylogeny. A phylogenetic confirmatory path analysis suggested that Rbmass and nest attachment can interact via a direct evolutionary link and also through an indirect link mediated through habitat (vegetation density). Phylogenetic ridge regression indicated that Top suspended nests were associated with species close to a maximum relative brain size, and that Rim suspended nests were associated with brain size radiations and probably with the exploration of new ecological niches. Our study provides evidence that the construction of nests with different attachment modes requires different levels of cognitive abilities, and we provide insights into the relationships between passerine brain size and nest attachment diversification.

Study on packing characteristics of powders with surface modification by nanoparticles

Powders with coated nanoparticles on the surface as a surface modification technique can alter the surface texture of the particles. This paper explored the additional number of nanoparticles on powder packing characteristics. The adhesion mode of nanoparticles and its influence on the inter-particle force in the system were discussed. The study found that the bulk density first increases and then decreases as the content of nanoparticles increases. The incorporation of nanoparticles reduces the inter-particle force, with the optimal mass fraction of nanoparticles being 0.25%, resulting in a 4.43% increase in bulk density. The attachment mode of nanoparticles was observed and analyzed through SEM, with five possible contact modes between particles identified. The change in the inter-particle force was quantitatively analyzed through the probability of each mode. The Bo number was used to establish a prediction model for bulk density, which yielded a highly accurate prediction.

Adult attachment and modes of resolving conflicts between partners in couple therapy

This article describes research correlating the attachment styles and modes of conflict resolution of forty couples with relationship problems. The sample consisted of two groups of heterosexual couples receiving couple psychotherapy: one in the process of reconciliation and the other in the process of divorce. The results of both groups showed partners mainly having a dismissing attachment style and using competition to resolve conflicts. There was a statistically significant correlation between the attachment styles of partners in the reconciliation group, and a high correlation between them in both groups in relation to their modes of resolving conflict. The results are compared with results from non-clinical couple populations and considered from the perspectives of attachment and other psychoanalytic theories.

Predicting Outcomes of Nanoparticle Attachment by Connecting Atomistic, Interfacial, Particle, and Aggregate Scales.

Predicting nanoparticle aggregation and attachment phenomena requires a rigorous understanding of the interplay among crystal structure, particle morphology, surface chemistry, solution conditions, and interparticle forces, yet no comprehensive picture exists. We used an integrated suite of experimental, theoretical, and simulation methods to resolve the effect of solution pH on the aggregation of boehmite nanoplatelets, a case study with important implications for the environmental management of legacy nuclear waste. Real-time observations showed that the particles attach preferentially along the (010) planes at pH 8.5 and the (101) planes at pH 11. To rationalize these results, we established the connection between key physicochemical phenomena across the relevant length scales. Starting from molecular-scale simulations of surface hydroxyl reactivity, we developed an interfacial-scale model of the corresponding electrostatic potentials, with subsequent particle-scale calculations of the resulting driving forces allowing successful prediction of the attachment modes. Finally, we scaled these phenomena to understand the collective structure at the aggregate-scale. Our results indicate that facet-specific differences in surface chemistry produce heterogeneous surface charge distributions that are coupled to particle anisotropy and shape-dependent hydrodynamic forces, to play a key role in controlling aggregation behavior.

Double-Labeling Method for Visualization and Quantification of Membrane-Associated Proteins in Lactococcus lactis.

Lactococcus lactis displaying recombinant proteins on its surface can be used as a potential drug delivery vector in prophylactic medication and therapeutic treatments for many diseases. These applications enable live-cell mucosal and oral administration, providing painless, needle-free solutions and triggering robust immune response at the site of pathogen entry. Immunization requires quantitative control of antigens and, ideally, a complete understanding of the bacterial processing mechanism applied to the target proteins. In this study, we propose a double-labeling method based on a conjugated dye specific for a recombinantly introduced polyhistidine tag (to visualize surface-exposed proteins) and a membrane-permeable dye specific for a tetra-cysteine tag (to visualize cytoplasmic proteins), combined with a method to block the labeling of surface-exposed tetra-cysteine tags, to clearly obtain location-specific signals of the two dyes. This allows simultaneous detection and quantification of targeted proteins on the cell surface and in the cytoplasm. Using this method, we were able to detect full-length peptide chains for the model proteins HtrA and BmpA in L. lactis, which are associated with the cell membrane by two different attachment modes, and thus confirm that membrane-associated proteins in L. lactis are secreted using the Sec-dependent post-translational pathway. We were able to quantitatively follow cytoplasmic protein production and accumulation and subsequent export and surface attachment, which provides a convenient tool for monitoring these processes for cell surface display applications.

Oriented immobilization of Thermomyces lanuginosus lipase by SBPs on silica-containing carriers for efficient bioproduction of biodiesel from Jatropha curcas oil

Biodiesel is recognized as green and renewable energy with low carbon intensity and less environmental impacts. The preparation of an economical immobilized lipase becomes much urgent challenge in the enzymatic production of biodiesel. In this study, recombinant Thermomyces lanuginosus lipase (TLL) was immobilized on the surface of silica-containing materials mediated by solid-binding peptides (SBPs). The obtained immobilized biocatalysts were effective in converting the oil from Jatropha curcas into biodiesel. The appropriate attachment mode of SBPs and TLL was investigated firstly, and the results showed that the activity of TLL was not negatively affected only when SBPs were fused at the C-terminus of TLL. Secondly, the immobilization efficiency of different SBPs (CecA, EctP1, VKT) on different silica-containing materials (SiO2, zeolite ZSM-5, SAR-100, MCM-41 and Na-Y) was systematically studied and it was concluded that the best immobilization efficiency was achieved for TLL-EctP1 immobilized on zeolite ZSM-5 (TLL- EctP1 @ZSM-5). TLL-EctP1 @ZSM-5 was found great performance in stability of pH, temperature, elution and storage. Eventually, biodiesel yield of 93 wt% was achieved using TLL-EctP1 @ZSM-5 as a biocatalyst to catalyze J. curcas oil for 48 h, and 81% of its initial yield was retained after 7 cycles of reuse. These results highlight the application of solid-binding peptides in enzyme immobilization for biocatalysts used in preparation of biodiesel or other chemicals.

Parental Attachment and Adolescent Moral Reaction Modes: The Serial Mediating Model of the Teacher-Student Relationship and Deviant Peer Affiliation.

Moral decision outcomes and emotional experiences after moral decisions are combined to create four moral reaction modes: happy victimizer (HV), unhappy victimizer (UHV), happy moralist (HM), and unhappy moralist (UHM). This study aimed to explore the relationships between parental attachment (PA) and adolescent moral reaction modes, and further examine the mechanism of the serial mediating effects of the teacher-student relationship (TS) and deviant peer affiliation (DP). A cross-sectional study was conducted in 2022 among 3053 students (including 1496 females) from four middle schools, four high schools, and three colleges in China using a voluntary and anonymous questionnaire. Our study reveals that PA was positively associated with HM modes and negatively associated with UHM, UHV, and HV modes. Both TS and DP serially or partly mediated the relationship between PA and adolescents' four moral reaction modes. This study uncovered significant social relationship pathways for moral reaction modes. TS and DP are two important mediators between PA and moral reaction modes. Secure parental attachment can develop positive teacher-student and peer relationships. This can then encourage adolescents to behave in more positive HM modes and fewer UHM/HV/UHV modes.

Entropic interactions of 2D materials with cellular membranes: Parallel versus perpendicular approaching modes

Understanding the interaction of 2D materials including graphene, boron nitride and MoS2 with biological systems is a growing topic of interest to many applications such as biosensors, drug delivery, gene therapy and nano-toxicity. In this paper, we show that the interaction of 2D materials with cellular membranes at its early stage of approaching is dominantly controlled by entropic forces. Recent experiments indicate that graphene sheets, depending on their size, can either undergo a near-orthogonal cutting or a parallel attachment mode of interaction with cell membranes. Here, we perform a set of integrated theoretical statistical mechanics analysis and coarse-grained molecular dynamics simulations to quantify the entropic energy barrier for these modes of interactions. Our results indicate that micro-sized graphene sheets prefer approaching a fluctuating membrane through a sharp corner, while nano-sized sheets are more likely to adhere to the cell membrane surface due to relatively low entropic energy cost that is comparable with thermal energy from random Brownian motions.

Dental structure and tooth attachment modes in the common fangtooth Anoplogaster cornuta (Valenciennes, 1833) (Actinopterygii; Trachichthyiformes; Anoplogastridae).

We studied the structure and attachment modes of the teeth of adult Anoplogaster cornuta using light- and scanning-electron microscopic techniques. All teeth were monocuspid, composed solely of orthodentin, and lacked a covering enameloid cap. Fourteen teeth were present in the oral jaws, with three teeth each on the left and right premaxilla and four teeth each on the left and right dentary. The anteriormost premaxillary and dentary teeth were considerably larger than the more posteriorly located ones. The oral jaw teeth were transparent, non-depressible and firmly ankylosed to their respective dentigerous bone by a largely anosteocytic bone of attachment. No evidence for replacement of the large oral jaw teeth was found in the analyzed adult specimens. The bone of attachment exhibited lower calcium and phosphorus concentrations and a higher Ca/P ratio than the orthodentin. The connection between dentinal tooth shaft and bone of attachment was stabilized by a collar of mineralized collagen fibers. In contrast to the oral jaw teeth, the pharyngeal teeth exhibited a ring-like fibrous attachment to their supporting bones. This mode of attachment provides the teeth with some lateral mobility and allows their depression relative to their supporting bones, which may facilitate intra-pharyngeal prey transport. In contrast, a firm ankylosis was observed in numerous small teeth located on the branchial arches. The function of these teeth is presumably to increase the tightness of the pharyngeal basket and thereby the retention of small prey items in a species living in a habitat with only sparse food supply. Our findings corroborate earlier statements on the tooth attachment modes of the oral jaw teeth of Anoplogaster cornuta, but provide new findings for the attachment modes of pharyngeal teeth in this species.

Swap and stop – Kinetochores play error correction with microtubules

Correct chromosome segregation in mitosis relies on chromosome biorientation, in which sister kinetochores attach to microtubules from opposite spindle poles prior to segregation. To establish biorientation, aberrant kinetochore–microtubule interactions must be resolved through the error correction process. During error correction, kinetochore–microtubule interactions are exchanged (swapped) if aberrant, but the exchange must stop when biorientation is established. In this article, we discuss recent findings in budding yeast, which have revealed fundamental molecular mechanisms promoting this “swap and stop” process for error correction. Where relevant, we also compare the findings in budding yeast with mechanisms in higher eukaryotes. Evidence suggests that Aurora B kinase differentially regulates kinetochore attachments to the microtubule end and its lateral side and switches relative strength of the two kinetochore–microtubule attachment modes, which drives the exchange of kinetochore–microtubule interactions to resolve aberrant interactions. However, Aurora B kinase, recruited to centromeres and inner kinetochores, cannot reach its targets at kinetochore–microtubule interface when tension causes kinetochore stretching, which stops the kinetochore–microtubule exchange once biorientation is established.

Thermal non-equilibrium simulation of diffuse and constricted anode attachments of a high intensity transferred arc

The arc attachment modes on anode of a high intensity argon arc with water-cooled constrictor are numerically investigated by a two-temperature model. An inelastic electron energy loss factor, representing the energy loss due to non-equilibrium chemical kinetic processes, is introduced to the electron energy equation. Two different attachment modes, i.e., diffuse and constricted anode attachments, are obtained based on the experimental conditions. Results for both anode attachment modes indicate that the temperature discrepancy between electrons and heavy particles is very pronounced in the arc fringes and in the regions close to the anode. By comparing the axial and radial Lorentz forces between the diffuse and constricted anode attachments, it is found that the larger axial and radial Lorentz forces in a constricted anode attachment are the main cause for the formation and maintenance of anode jet. The effects of inelastic electron energy loss on different anode attachment modes are discussed and the results indicate that it is very important to consider the chemical non-equilibrium processes in an appropriate way for predicting arc attachment modes on anode reasonably.

Spatial variation in taxonomic and functional composition of periphytic algae in lakes of Karelian Isthmus

Variation in species and functional structure of periphytic algae community in relation to chemical, physical, climatic and spatial factors was studied in 55 lakes of Karelian Isthmus. To assess factors driving functional structure, all algal species were divided into eight functional groups that differ in cell/colony morphology and attachment mode to the substrate. Variance partitioning analysis showed that environmental factors (chemical and climatic) prevailed over spatial variables in explaining variation in periphyton species structure. On the contrary, periphyton functional structure depended more on spatial variables than on environmental factors (chemical and physical). This suggests that dispersal processes which are dependent on landscape characteristics of the region and hydrological connectivity along individual river networks play a more significant role in spatial variation of functional composition of periphytic algae.

Evidence for Host Selectivity and Specialization by Epizoic Chelonibia Barnacles Between Hawksbill and Green Sea Turtles

Epibionts are organisms that utilize the exterior of other organisms as a living substratum. Many affiliate opportunistically with hosts of different species, but others specialize on particular hosts as obligate associates. We investigated a case of apparent host specificity between two barnacles that are epizoites of sea turtles and illuminate some ecological considerations that may shape their host relationships. The barnacles Chelonibia testudinaria and Chelonibia caretta, though roughly similar in appearance, are separable by distinctions in morphology, genotype, and lifestyle. However, though each is known to colonize both green (Chelonia mydas) and hawksbill (Eretmochelys imbricata) sea turtles, C. testudinaria is >5 times more common on greens, while C. caretta is >300 times more common on hawksbills. Two competing explanations for this asymmetry in barnacle incidence are either that the species’ larvae are spatially segregated in mutually exclusive host-encounter zones or their distributions overlap and the larvae behaviorally select their hosts from a common pool. We indirectly tested the latter by documenting the occurrence of adults of both barnacle species in two locations (SE Florida and Nose Be, Madagascar) where both turtle species co-mingle. For green and hawksbill turtles in both locations (Florida: n = 32 and n = 275, respectively; Madagascar: n = 32 and n = 125, respectively), we found that C. testudinaria occurred on green turtles only (percent occurrence – FL: 38.1%; MD: 6.3%), whereas the barnacle C. caretta was exclusively found on hawksbill turtles (FL: 82.2%; MD: 27.5%). These results support the hypothesis that the larvae of these barnacles differentially select host species from a shared supply. Physio-biochemical differences in host shell material, conspecific chemical cues, external microbial biofilms, and other surface signals may be salient factors in larval selectivity. Alternatively, barnacle presence may vary by host micro-environment. Dissimilarities in scute structure and shell growth between hawksbill and green turtles may promote critical differences in attachment modes observed between these barnacles. In understanding the co-evolution of barnacles and hosts it is key to consider the ecologies of both hosts and epibionts in interpreting associations of chance, choice, and dependence. Further studies are necessary to investigate the population status and settlement spectrum of barnacles inhabiting sea turtles.

Particle flocculation in a stirred tank: A microscopic test by coupled CFD-DEM approach

Particle flocculation in a stirred tank was numerically investigated by a coupled CFD-DEM approach, in which a microscopic test in a typical zone was first proposed instead of solving the full-scale particle field. The flocculation kinetics was described by the Johnson-Kendall-Roberts (JKR) theory, followed by calibration of surface energy parameter. A Volume of Fluid (VOF) model was employed to capture the interface between liquid and air. The two-way coupling of fluid and particle was achieved by resolving pressure gradient force and Gidaspow’s drag force in the momentum equations. Based upon the qualitative and quantitative validation tests in air-water interface pattern and fluid tangential velocity, respectively, the particle coordination number and flocs fractal properties (e.g. fractal dimension, voidage, effective density) were investigated considering the effect of impeller speed. Results show that the number of particles first increases with particle coordination number and then decreases, and is further positively correlated with the stirring intensity in lower coordination numbers (0−3) while negatively correlated in higher coordination numbers (≥5). The influences of turbulence dissipation rate on the average particle coordination number were also investigated in radial, tangential, and axial directions. The mean floc size decreases with impeller speed, however, the fractal dimension increases in a certain range. The voidage increases with the daughter-particle number in a floc while the effective density of flocs is inversely proportional to the floc size. It is recommended to adopt operations that facilitate the one-by-one attachment mode and syneresis for forming relatively large and compact flocs.