Internal Structure Research Articles

Facile Semiconductor p–n Homojunction Nanowires with Strategic p-Type Doping Engineering Combined with Surface Reconstruction for Biosensing Applications

HighlightsA novel photoelectrochemical (PEC) photosensor composed of GaN nanowire-on-Si platform demonstrates record-high responsivity of 247.8 mA W−1 with ultra-stable operation characteristics.Strategic internal and external band structure engineering of semiconductor nanowires promotes efficient PEC reaction via controlling carrier dynamics while preserving nanowires from material degradation.The glucose sensing system is constructed to successfully analyze blood glucose levels in real human serum samples, featuring a high sensitivity of 0.173 µA µM−1 cm−2 and a low detection limit of 0.07 µM.

Selective Enhancement of Viewing Angle Characteristics and Light Extraction Efficiency of Blue Thermally Activated Delayed Fluorescence Organic Light-Emitting Diodes through an Easily Tailorable Si3N4 Nanofiber Structure.

We selectively improved the viewing angle characteristics and light extraction efficiency of blue thermally activated delayed fluorescence (TADF) organic light-emitting diodes (OLEDs) by tailoring a nanofiber-shaped Si3N4 layer, which was used as an internal scattering layer. The diameter of the polymer nanofibers changed according to the mass ratio of polyacrylonitrile (PAN) and poly(methyl methacrylate) (PMMA) in the polymer solution for electrospinning. The Si3N4 nanofiber (SNF) structure was fabricated by etching an Si3N4 film using the PAN/PMMA nanofiber as a mask, making it easier to adjust parameters, such as the diameter, open ratio, and height, even though the SNF structure was randomly shaped. The SNF structures exhibited lower transmittance and higher haze with increasing diameter, showing little correlation with their height. However, all the structures demonstrated a total transmittance of over 80%. Finally, by applying the SNF structures to the blue TADF OLEDs, the external quantum efficiency was increased by 15.6%. In addition, the current and power efficiencies were enhanced by 23.0% and 25.6%, respectively. The internal light-extracting SNF structure also exhibited a synergistic effect with the external light-extracting structure. Furthermore, when the viewing angle changed from 0° to 60°, the peak wavelength and CIE coordinate shift decreased from 20 to 6 nm and from 0.0561 to 0.0243, respectively. These trends were explained by the application of Snell's law to the light path and were ultimately validated through finite-difference time-domain simulations.

In situ Electrical Impedance Tomography for Visualizing Water Transportation in Hygroscopic Aerogels.

The global water crisis demands immediate attention, and atmospheric water harvesting (AWH) provides a viable alternative. However, studying the real-time subtle relationship between water absorption, diffusion, and internal structure for hygroscopic materials is challenging. Herein, a dynamic visualization technique is proposed that utilizes an in situ electrical impedance tomography (EIT) system and a precise reconstruction algorithm to achieve real-time monitoring of the water sorption process within aerogels from an internal microstructural perspective. These results can be inferred that composites' pore sizes affecting the kinetics of their moisture absorption. In addition, the diffusion path of moisture absorption and the distribution of stored moisture inside aerogels exhibit intrinsic self-selective behavior, where the fiber skeleton of the aerogel plays a crucial role. In summary, this work proposes a generic EIT-based technique for the in situ and dynamic monitoring of the hygroscopic process, pointing to an entirely new approach regarding research on AWH materials.

An approach to the effects of stellar rotation on the theoretical apsidal motion constants. Calculations from 0.40 M_sol to 25.0 M_sol

The most reliable sources for determining absolute stellar parameters are the double-lined eclipsing binary systems. Some of these systems also show apsidal motion, characterized by the variable log k$_2$. This point grants us the possibility of investigating the stellar interior, specifically the degree of stellar mass concentration. The first studies carried out about four decades ago on this topic showed appreciable discrepancies not only with respect to the comparison between the observed absolute dimensions and their theoretical counterparts, but mainly concerning the degree of mass concentration through the analysis of their apsidal motions. Fortunately, this scenario has been gradually improving with the advances in the quality of observational techniques and advances in the input physics of the evolutionary stellar models (e.g. opacities, thermonuclear reactions, equations of state, numerical techniques). These new developments in the input physics has improved the comparison between observations and the values predicted by theory, including the apsidal motion rates. This progress has lead us to investigate second-order effects such as rotation and dynamic tides. In this paper we deal with the effects of rotation on the degree of mass concentration. The stellar models were calculated using the MESA package. The mass range studied here was 0.40 to 25.0 M$_ odot $ for a generic chemical composition characterized by X = 0.70 and Z = 0.02. The present models were computed without taking into account core overshooting in order to highlight the effects of rotation. Each model was followed from the pre-main sequence until the central hydrogen content is of the order of or less than 0.03, covering the range of masses and evolutionary status of the double-lined eclipsing binaries showing apsidal motion. Regarding the calculation of the internal structure coefficients bf we integrated the Radau equation using the fifth-order Runge-Kutta method and a tolerance level of 10$^ $. As an auxiliary tool, homology transformations have been used to explain, qualitatively, how the equation of state, thermonuclear reactions, and convection impact the degree of mass concentration of the models. In our past studies on the effects of rotation on log k$_2$ an average correction was used for all models together. For this a small range of masses (2.0, 7.0, 15.0 M$_ odot $) has been used. In the present paper the corrections due to the effects of rotation in log k$_2$ are presented for each mass individually and for three evolutionary phases. This point is particularly important bf given that these corrections show a clear dependence on the mass and on the evolutionary status. Such corrections can be easily introduced into the theoretical calculation of apsidal motion rates through a linear equation. A typical correction due to the rotation effects is of the order of -0.03 in log k$_2$.

Experimental study of mechanical properties of artificial dam for coal mine underground reservoir under cyclic loading and unloading

This study investigates the stability of an artificial dam used in an underground reservoir in a coal mine under periodic weighting imposed by overlying rock strata. For this purpose, cyclic loading and unloading tests with different stress amplitudes were designed. Differences in the mechanical performance of the artificial dam with and without overlying strata were analyzed using a uniaxial compression test. The mechanical properties of the structure under constant-amplitude cyclic loading and unloading were characterized. Further, the law of influence of stress amplitude on stability was discussed. A formula for predicting the mechanical performance of the artificial dam with its overlying rocks (hereafter referred to as the complex) was finally derived and was suitable for clarifying the law of damage in the complex under cyclic loading and unloading. The results showed that the complex had changed the internal structure of rocks. The strength and deformation of the complex were intermediate to that of either single structure. All three underwent brittle failure. During the constant-amplitude loading and unloading tests, the hysteresis loop could be divided into three phases, namely, sparse, dense, and sparse again, with a shift in the turning point in rock deformation memory effect. As the stress amplitude increased during the test, the damping ratio of the specimens decreased, and the area of the hysteresis loop increased non-linearly. The dynamic elastic modulus decreased first and then increased. The confidence interval for the formula fitted based on the test results was above 97%. Damage to the complex caused by constant-amplitude loading and unloading could be divided into three stages. An increase in peak stress served as a catalyst for the evolution of small cracks within the specimens into median and large cracks, thereby accelerating the damage process.

Enabling 3D CT-scanning of cultural heritage objects using only in-house 2D X-ray equipment in museums

Visualizing the internal structure of museum objects is a crucial step in acquiring knowledge about the origin, state, and composition of cultural heritage artifacts. Among the most powerful techniques for exposing the interior of museum objects is computed tomography (CT), a technique that computationally forms a 3D image using hundreds of radiographs acquired in a full circular range. However, the lack of affordable and versatile CT equipment in museums, combined with the challenge of transporting precious collection objects, currently keeps this technique out of reach for most cultural heritage applications. We propose an approach for creating accurate CT reconstructions using only standard 2D radiography equipment already available in most larger museums. Specifically, we demonstrate that a combination of basic X-ray imaging equipment, a tailored marker-based image acquisition protocol, and sophisticated data-processing algorithms, can achieve 3D imaging of collection objects without the need for a costly CT imaging system. We implemented this approach in the British Museum (London), the J. Paul Getty Museum (Los Angeles), and the Rijksmuseum (Amsterdam). Our work paves the way for broad facilitation and adoption of CT technology across museums worldwide.

Effect of Nano-TiO2 and Polypropylene Fiber on Mechanical Properties and Durability of Recycled Aggregate Concrete

In order to promote the engineering application of recycled concrete, the effects of PPF and nano-TiO2 dioxide on the mechanical properties and durability of recycled concrete were studied.Polypropylene fiber recycled concrete(PRAC) and nano-TiO2 recycled concrete(TRAC) were prepared by adding different volume contents of PPF and nano-TiO2. The experimental findings demonstrated that the PPF and nano-TiO2 improved the splitting tensile strength of RAC better than the compressive strength. When the volume content of nano-TiO2. and PPF is 0.8% and 1.0%, respectively, the corresponding splitting tensile strength of concrete reaches the maximum value(3.4 and 3.7 MPa). The contribution rates of nano-TiO2 and PPF with different volume contents to the mechanical properties of RAC have optimal values, which are 0.4 and 1.0%, respectively. The incorporation of nano-TiO2 and PPF can effectively inhibit the loss of RAC mass and the generation of pores under freeze–thaw conditions, and slow down the decrease of dynamic elastic modulus. When the volume content of PPF is 1.0% and the volume content of nano-TiO2 is 0.4%, the protection effect on the internal structure of RAC is better, and its carbon resistance is better. The results of RSM model analysis and prediction show that both PPF and nano-TiO2 can be used as admixture materials to improve the mechanical properties and durability of RAC, and the comprehensive improvement effect of PPF on RAC performance is better than that of nano-TiO2.

The Personality Inventory for DSM-5-Brief Form (PID-5-BF): Psychometric indicators in a Brazilian community sample

Objective: To investigate psychometric properties (internal structure, convergent/discriminant validity, internal consistency, and test-retest) of the Personality Inventory for DSM-5-Brief Form (PID-5-BF) in a Brazilian community sample. Method: This is a study with a psychometric design. A sample of 527 adults from the general population (69.9% women; 33.5 ± 14.0 years; 74.0% ≥ 12 years education) responded to the instrument online after the study was disseminated on social networks and to the researchers’ contacts. The NEO-PI-R and sociodemographic questionnaire were applied besides the PID-5-BF, and a retest was applied 15-30 days after the initial assessment for reliability assessment. Data were analyzed using statistical techniques (IBM SPSS19 and Factor20); the significance level was set at p ≤ 0.05 for all the analyses. Results: Internal consistency was verified using Cronbach’s alpha and was adequate (domains α ≥ 0.69; total α = 0.87), in addition to test-retest reliability (domains ICC ≥ 0.82; total ICC = 0.95). Divergences were found between the PID-5-BF different domains despite them being significantly correlated with each other. Convergent validity with the NEO-PI-R was adequate, with moderate/strong correlations between the domains theoretically associated (r > 0.38). The internal structure (Exploratory Factor Analysis) indicated that the original five-factor model (CFI = 0.991; TLI = 0.986; RMSEA = 0.033) and one-factor model were adequate (CFI = 0.908; TLI = 0.899; RMSEA = 0.089. Conclusions: The findings support using the PID-5-BF Brazilian version, which presented adequate psychometric properties comparable to the original version. This instrument can be helpful in the clinical and research fields to screen general and specific traits of personality pathology. Future studies are suggested to expand the psychometric findings among clinical samples, confirming the instrument’s scope of reach.

The application of dairy products and their derivatives as edible inks in 3D printing technology: A review

SummaryThree‐dimensional (3D) printing technology digitally designs and manufactures objects through computer‐controlled processes. It requires raw materials with specific rheological properties for extrusion and shape retention. Dairy products hold promise for 3D printing due to their ability to form structures and their nutritional value. However, the quality of 3D printing with dairy products relies on the properties of the printing ink and printer parameters, presenting challenges for practical applications. This work provided a summary of the suitability of dairy‐based 3D printed products, discussing physicochemical modifications and additives to enhance their suitability and nutritional properties. The internal structure and composition of printing inks derived from dairy products are closely linked to their printing performance. Physicochemical modifications and additives effectively improve printability and the nutritional aspects of dairy inks. The 3D printing suitability of dairy inks can be enhanced through physical, chemical or enzymatic treatments. The gel properties of dairy products can be improved by mixing them with hydrophilic gels, introducing calcium, and incorporating lipids to enhance the 3D printing performance of dairy products. 3D printing technology enables the customisation of dairy products with personalised control of nutritional content, meeting the increasing consumer and market demand for healthier foods. In the future, 3D printed dairy products are expected to constitute convenient and quick nutritious food and enter home kitchens.

The relationship between conctere composition and structural stability in case of fire

A series of disasters caused by fire have made engineers aware that understanding the consequences of fire is essential, as human lives depend on it, and it can also cause significant material damage. The structural integrity of structures during and after a fire, including their stability, can be better ensured if we accurately understand the effects of fire. Of course, the effects of fire do not always lead to significant damage, but in many cases they do. Fire protection is intended, on the one hand, to ensure that buildings remain stable under fire for a certain period, which is necessary to enable occupants to escape safely and, on the other hand, to minimize damage to building structures. The concrete composition, i.e., the structure's microstructure, significantly influences the stability of reinforced concrete structures in the event of fire or heat. In the case of concrete, in addition to changes in the internal material structure in the event of fire, spalling has also appeared recently, largely due to the denser concrete structure. In summary, the higher strength of concrete and the concomitant change in the test strength will lead to spalling, which will have a major impact on the stability of structures under fire. Both small-element (fiber efficiency, aggregate efficiency) and large-element tests have been carried out to verify this. The small-element tests were carried out in an electric furnace to monitor possible concrete surface delamination and strength loss. The small-element tests can be used to select concrete compositions for the large-element tests. Based on their experimental results, an increase in the fire resistance limit of a structural element can be achieved by reducing the delamination of the concrete surface when plastic fibers are added to the concrete. However, if a further increase in the fire resistance limit is required, a change in the type of cement or a modification of the supplementary material may be necessary to increase the residual strength value. Overall, the microstructure of concrete has a significant impact on the stability of structures in the event of a fire.

Dynamic microvilli sculpt bristles at nanometric scale

Organisms generate shapes across size scales. Whereas patterning and morphogenesis of macroscopic tissues has been extensively studied, the principles underlying the formation of micrometric and submicrometric structures remain largely enigmatic. Individual cells of polychaete annelids, so-called chaetoblasts, are associated with the generation of chitinous bristles of highly stereotypic geometry. Here we show that bristle formation requires a chitin-producing enzyme specifically expressed in the chaetoblasts. Chaetoblasts exhibit dynamic cell surfaces with stereotypical patterns of actin-rich microvilli. These microvilli can be matched with internal and external structures of bristles reconstructed from serial block-face electron micrographs. Individual chitin teeth are deposited by microvilli in an extension-disassembly cycle resembling a biological 3D printer. Consistently, pharmacological interference with actin dynamics leads to defects in tooth formation. Our study reveals that both material and shape of bristles are encoded by the same cell, and that microvilli play a role in micro- to submicrometric sculpting of biomaterials.

A Structural Study on Absorption of Lysozyme in Amorphous Starch Microspheres.

The potential of using proteins as drugs is held back by their low stability in the human body and challenge of delivering them to the site of function. Extensive research is focused on drug delivery systems that can protect, carry, and release proteins in a controlled manner. Of high potential are cross-linked degradable starch microspheres (DSMs), as production of these is low-cost and environmentally friendly, and the products are degradable by the human body. Here, we demonstrate that DSMs can absorb the model protein lysozyme from an aqueous solution. At low amounts of lysozyme, its concentration in starch microspheres strongly exceeds the bulk concentration in water. However, at higher protein contents, the difference between concentrations in the two phases becomes small. This indicates that, at lower lysozyme contents, the absorption is driven by protein-starch interactions, which are counteracted by protein-protein electrostatic repulsion at high concentrations. By applying small-angle X-ray scattering (SAXS) to the DSM-lysozyme system, we show that lysozyme molecules are largely unaltered by the absorption in DSM. In the same process, the starch network is slightly perturbed, as demonstrated by a decrease in the characteristic chain to chain distance. The SAXS data modeling suggests an uneven distribution of the protein within the DSM particles, which can be dependent on the internal DSM structure and on the physical interactions between the components. The results presented here show that lysozyme can be incorporated into degradable starch microspheres without any dependence on electrostatic or specific interactions, suggesting that similar absorption would be possible for pharmaceutical proteins.

National Park Service Internal Structures Toward Agency Resilience: A Mixed-Methods, Multi-Site, Mesoscale Investigation

Agencies focused on protected areas’ conservation and recreation require internal capacity-building to enhance their organizational resilience (the ability to adapt and persist). Yet, internal capacity-building is often underemphasized as agencies attend to external relationships. This omission can lessen an agency’s ability to adapt to emergent stressors and opportunities. Specifically, relationships within an agency’s groups (i.e., divisions)—the intra-organizational mesoscale between individuals and whole organizations—can increase an agency’s ability to efficiently build resilience-enhancing adaptive capacity. The U.S. National Park Service (NPS) adopted this mesoscale in their Urban Agenda goal of One NPS, or building resilience-enhancing, agency-wide internal relationships. We investigated intra-organizational relationships in this context, examining relationships within (i.e., bonds) and across (i.e., bridges) three NPS groups: parks (physical spaces), programs (community outreach), and offices (administrative functions). Pairing qualitative interviews with quantitative social network analysis in Detroit, Tucson, and Boston, we examined internal relationship prevalence, supports, and opportunities. The NPS has program and office presence in each of these three urban areas but different proximities to national park units, which are the typical face of the NPS. Across these urban areas, we found that the parks group exhibits more bonds (park-to-park relationships), the programs group exhibits more bridges (program-to-park or program-to-office), and the offices group exhibits a mixture of bonds and bridges. To further One NPS and organizational resilience, cultivating bridges among the three groups is key. This investigation may inform a more strategic focusing of an agency’s limited resources. We highlight five directions for protected area managers’ consideration toward this aim: build bridges locally among groups; consider group composition when identifying divisions (i.e., programs appear more heterogeneous or dissimilar from each other than do the park and office groups); reflect on parks’ centrality to NPS identity and relationships; seek organizational structures supportive of relationship development; and focus on the organizational mesoscale for resilience-enhancing adaptive capacity. These directions for strategic focusing of organizational resources are based in the longstanding work of the NPS but ultimately transcend this single agency, providing targeted guidance for protected area agencies in building internal capacity toward external, public-oriented goals.

Wavy grain in sycamore maple (Acer pseudoplatanus) — a structural analysis of xylem and phloem

Summary Wavy grain (fiddle back) in trees has attracted the interest of both science and industry due to its aesthetic and economic importance. As the underlying causes of this particular structural feature in trees remain uncertain, this study investigates the possibility of non-invasively detecting wavy grain patterns within tree bark tissue of sycamore maple (Acer pseudoplatanus). Wavy grain, characterized by alternating light and dark stripes on the wood surface, is highly valued in the production of musical instruments. This research explores the potential of employing transmission light microscopy and microcomputer tomography (μCT) to examine the internal structure of phloem tissue to inspect whether the wavy grain structure found in the xylem continues in the bark. The investigation of phloem tissue proved challenging due to its irregular cellular arrangement. Nonetheless, slight phloem fibre deviations were observed in individual trees. However, no definite connection was found between the periodic oscillations of the xylem fibre tissue and the structure of the phloem in a given area. Variability in wavy grain expression among the xylem of the trees posed an additional challenge, with amplitudes and wavelengths differing across specimens. The application of μCT offered advantages over traditional sample preparation, enabling the study of the anatomical structure across larger areas and multiple depths without altering the specimen. This study sheds light on the potential of employing advanced imaging techniques to detect wavy grain patterns, providing insights that could benefit industries reliant on high-quality wood, such as musical instrument crafting and forestry.

Enhanced Quantum Control of Individual Ultracold Molecules Using Optical Tweezer Arrays

Control over the quantum states of individual molecules is crucial in the quest to harness their rich internal structure and dipolar interactions for applications in quantum science. In this paper, we develop a toolbox of techniques for the control and readout of individually trapped polar molecules in an array of optical tweezers. Starting with arrays of up to eight Rb and eight Cs atoms, we assemble arrays of RbCs molecules in their rovibrational and hyperfine ground state with an overall efficiency of 48(2)%. We demonstrate global microwave control of multiple rotational states of the molecules and use an auxiliary tweezer array to implement site-resolved addressing and state control. We show how the rotational state of the molecule can be mapped onto the position of Rb atoms and use this capability to readout multiple rotational states in a single experimental run. Further, using a scheme for the midsequence detection of molecule formation errors, we perform rearrangement of assembled molecules to prepare small defect-free arrays. Finally, we discuss a feasible route to scaling to larger arrays of molecules. Published by the American Physical Society 2024

Preparation and modification of PVDF membrane via VIPS method for membrane distillation

Membrane distillation (MD) is a promising technology for treating high-salinity mine water. However, MD membranes are known to have low membrane flux and are prone to fouling. In this study, we used the cost-effective and controllable vapor-induced phase separation (VIPS) technology to prepare polyvinylidene difluoride (PVDF) membranes, replacing the traditional immersion precipitation method and optimizing the membrane structure by including LiCl and acetone as porogen in the casting solution. The results showed that the membrane prepared using the VIPS method exhibited a highly open interconnected porous surface. Unlike traditional MD membranes with a dense epidermal layer and large finger-like pores, these optimized membranes had a symmetrical and uniform internal structure, leading to a high flux of 8.62 kg·(m2·h)−1 during direct contact membrane distillation testing. Different porogens produced varied results on the VIPS process and varying effects on membrane structure. The use of LiCl promoted the formation of PVDF β-phase, resulting in a decrease in the number of spherical nodules on the membrane surface, as well as improved density and smoothness. Consequently, this reduced fouling risk during membrane distillation while slightly decreasing membrane flux. On the other hand, acetone rapidly evaporated during the VIPS process, facilitating pre-gelatinization and α-phase formation of PVDF. This concurrent effect effectively restricted excessive nodule growth on the membrane surface, endowing the membrane with antifouling capabilities while preserving high flux.

Electronic Delocalization Engineering of β‐AsP Enabled High‐Efficient Multisource Logic Nanodevices

AbstractDelocalized electron and phonon structures are directives for rationally tuning the intrinsic physicochemical properties of 2D materials by redistributing electronic density. However, it is still challenging to accurately manipulate the delocalized electron and systematically study the relationships between physiochemical properties and practical nanodevices. Herein, the effects of delocalized electrons engineering on blue‐arsenic‐phosphorus (β‐AsP)‐based practical devices are systematically investigated via implementing vacancies or heteroatom doping. A tendency of carrier conductivity property from “half‐metal” to “metal” is initially found when tuning the electronic structure of β‐AsP with adjustable vacancy concentrations below 2 at% or above 3 at%, which can be ascribed to the introduction of delocalized electrons that cause asymmetric contributions to the electronic states near the implementation site. In optical logic device simulations, broadband response, triangular wave circuit system signal, and reverse polarization anisotropy are achieved by adjusting the vacancy concentration, while extinction ratios are as high as 1561. The electric and thermic‐logic devices realize the highest available reported giant magnetoresistance (MR) up to 1013% and 1039% at vacancy concentrations of 1.67% and 0.89%, respectively, which is significantly superior to the reports. The results shed light on the electronic delocalization strategy of regulating internal structures to achieve highly efficient nanodevices.

Psychometric properties of the Norwegian version of the Strength and Difficulties Questionnaire in a preschool sample

Purpose The Strength and Difficulties Questionnaire (SDQ) is widely used internationally, however less so in preschool populations and validations studies are thus needed. This study examined the psychometric properties of the Norwegian version parent report of the SDQ – preschool version (SDQ 2–4). Materials and methods Parents of 289 Norwegian children in the age span 1–6 years old filled out the SDQ 2–4, the Child Behavior Checklist (CBCL), and background information. Internal consistency, factor structure, and convergent validity were assessed. Results The results showed satisfying internal consistency for the total difficulties score, but worse for some of the subscales. The five-factor structure showed a good fit. Good convergent and divergent validity was found in terms of correlations with CBCL. Sex differences were found on all scales, boys scoring higher on all problem scales. Conclusions The SDQ 2–4 can be a promising instrument to screen for emotional and behavioral difficulties among Norwegian preschoolers, particularly in high-risk populations.

Ultrasmall Single-Chain Nanoparticles Derived from Amphiphilic Alternating Copolymers.

The collapse or folding of an individual polymer chain into a nanoscale particle gives rise to single-chain nanoparticles (SCNPs), which share a soft nature with biological protein particles. The precise control of their properties, including morphology, internal structure, size, and deformability, are a long-standing and challenging pursuit. Herein, a new strategy based on amphiphilic alternating copolymers for producing SCNPs with ultrasmall size and uniform structure is presented. SCNPs are obtained by folding the designed alternating copolymer in N,N-dimethylformamide (DMF) and fixing it through a photocatalyzed cycloaddition reaction of anthracene units. Molecular dynamics simulation confirms the solvophilic outer corona and solvophobic inner core structure of SCNPs. Furthermore, by adjusting the length of PEG units, precise control over the mean size of SCNPs is achieved within the range of 2.8 to 3.9nm. These findings highlight a new synthetic strategy that enables enhanced control over morphology and internal structure while achieving ultrasmall and uniform size for SCNPs.

Predicting the rutting behaviour of asphalt concrete in the modified wheel tracking test using DEM and a cohesive viscoelastic–elastoplastic-damage contact model

AbstractThis study used an advanced modelling approach capable of capturing the complex behaviour of asphalt concrete to model the modified wheel tracking test using a recent advanced experimental test set-up in accordance with ASTM D8292-20. The modelling approach uses the discrete element method (DEM) to naturally produce the heterogeneous internal structure and governs the behaviour of asphalt concrete at the grain level by an interparticle contact model. The contact model used is capable of characterising the rate and time dependency, viscoelastic-damage, and plastic-damage behaviour of asphalt concrete utilising the coupling of an elastoplastic-damage law with a viscoelastic-damage law. Unlike the conventional wheel tracking tests run in a fixed boundary condition (fully confined), the modified wheel tracking test considers the effect of boundary conditions on the rutting behaviour of asphalt mixes. Through comparisons and verifications with laboratory data of the rutting test at different boundary conditions (fully confined and unconfined), the modelling approach shows its capability of capturing the rutting behaviour of asphalt concrete in the modified wheel tracking test. Micromechanics analysis shows that the third (tertiary) stage of rutting behaviour is due to the weakening of the internal structure of the asphalt samples with contact bond breaks over time, which is found in the unconfined test. Meanwhile, the tertiary stage hardly occurs in the fully confined test once densification leads to contact of the aggregate–aggregate skeleton, forming a rigid structure to resist the load with lateral support from the fixed boundary condition. Finally, a parametric study was also conducted to provide further insight into the current testing set-up, including the effect of the sample size and boundary condition on the rutting behaviour of asphalt concrete.