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[Display omitted] • A curing depth prediction model based on Jacob's working curve was established. • Correction factor n was introduced to correct critical curing energy. • Printing process was quantitatively monitored through the degree of conversion of functional group and photopolymer opto-rheological properties. • A method for quick-selection of printing parameters was proposed and verified, and the final printing accuracy reached 12 μm. Vat photopolymerization is a widely employed additive manufacturing (AM) technique that commonly applying a digital light processing (DLP) light engine to provide a patterned light source. Notably, printing extreme-size structures is challenging, and the selection of printing parameters was currently highly reliant on repeatable trial-and-error experiments. In this work, a theoretical model for curing depth prediction was established by observing the effect of light intensity. A correction factor n was introduced to optimize the relationship among the critical curing energy, exposure time, and light intensity. Forming experiments verified the accuracy of the proposed theoretical curing depth prediction model, and a correction factor n equal to 0.75 was obtained. Optical rheological characterization experiments and Fourier transform infrared spectroscopy (FTIR) supported the quantitative characterization of the DLP printing process while revealing a stepwise transition during photocuring. Finally, a guidance for quick selection of the optimal curing time for 3D structure was obtained and applied to the high-precision microstructure printing process. High-fidelity microneedle arrays with 12 μm details were printed. This method of rapid selection of printing parameters and printing microstructures with high-precision details can potentially be used in the field of 3D bioprinting. [ABSTRACT FROM AUTHOR]

• Conventional springback model works in micro bending using the surface layer model. • The model underestimates the channel height in microforming of parallel channels. • The transverse stress is found to play an important role. • An improved model was developed considering the transverse stress. • The shift distance of the neutral plane and channel height are better captured. To satisfy the higher accuracy requirement in the microforming of thin-walled structures, the springback behavior under miniaturizing dimensions need to be accurately predicted and controlled. However, as the feature size approaches the thickness in microforming, many assumptions in conventional springback model for macroforming are not valid making these models can hardly provide effective springback analysis in microforming. In the present work, the applicability of a springback analytical framework of conventional stretch-bending was first explored via bending tests of 0.1 mm-thick SS316L sheets under different holding conditions with a punch radius from 3 to 5 mm which is much greater than the thickness. The analytical springback angle results agree with the experimental ones with the maximum error of 4.2% for different punch radii, grain sizes and stretching forces conditions, indicating the correctness of the model. The model was further verified in the microforming of parallel channels with a fillet radius of 0.15 mm. Finite element simulations were conducted to obtain the stretching loads for each channel. However, a significant underestimation of the channel height after springback for over 15% was found especially for the middle channel. The transverse stress is revealed to be no longer neglectable due to the strong stretching load and the small die radius during the microforming of parallel channels, which substantially contributes to yielding, hardening and thickness reduction in the stretch-bending area. In addition, the uneven stretching also affects the springback angle and channel height, which is caused by the nonuniform plastic deformation of the adjacent channels. By incorporating the effects of the transverse stress and the non-uniform stretching loads, an improved springback model was developed for microforming of parallel channels in this work. The shift distance of the neutral plane is better estimated by the improved model than by the conventional one. The predictive heights by the improved model are also revealed to agree with the experimental ones during the microforming of parallel channels with a maximum error of less than 5%. [Display omitted] [ABSTRACT FROM AUTHOR]

Membrane electrode assembly (MEA) is the core component of proton exchange membrane fuel cells (PEMFCs). The multi-phase channels inside the catalyst layer of the MEA are generally messy, thus leading to inefficient mass transfer characteristics. Meanwhile, the corrosion of carbon carriers and agglomeration of catalyst will aggravate the performance degradation and reduce its service life. This study presented an MEA with cathode ordered catalyst layer to improve the mass transfer characteristics and durability. The TiO 2 nanowire arrays were prepared on the porous surface of carbon paper by seed-assisted hydrothermal reaction, the catalyst was applied on the surfaces of TiO 2 carrier and PEM uniformly by ultrasonic spraying. The microstructure characterization and electrochemical tests were conducted, and the results showed that the peak power of the cathode ordered MEA (CO-MEA) can reach 539.5 mW/cm2 at a platinum loading of 0.21 mg/cm2. Furthermore, the MEA with ordered cathode catalyst layer can maintain a higher output voltage under high current density, indicating that the MEA's internal three-phase reaction channels have been significantly improved. Finally, by comparing with the other processes, it was found that the combination of ultrasonic spraying and cathode ordered structures would be a promising solution for developing efficient and stable MEA. • CO-MEA was prepared based on hydrothermal reaction and ultrasonic spraying. • Morphological characterization and electrochemical experiments were carried out. • The CO-MEA not only provided good mass transfer, but also a large reaction area. [ABSTRACT FROM AUTHOR]

Experiments were conducted at a diesel engine with exhaust gas recirculation (EGR), and the particulates produced by the combustion of Fischer-Tropsch (F-T) diesel, biodiesel as well as diesel were collected. The influences of fuel characteristics upon the morphology, nanostructure and oxidation reactivity of particles were explored by high-resolution transmission electron microscope (HRTEM), Raman spectroscopy (RS) and thermogravimetry (TGA). The results show that compared with diesel, F-T diesel particulates possess smaller fractal dimension (D f) and fringe tortuosity (T f), lower the area ratio of D1 peak to G peak (A D1 /A G) and half peak width of D1 peak (D1-FWHM), longer fringe length (L a), shorter separation distance (d), higher oxidation characteristic temperature and apparent reactive energy (E a), while biodiesel particulates exhibit the opposite features. Among the samples, F-T diesel particulates display the highest graphitization degree and the lowest oxidation reactivity, biodiesel particulates present the most disorderly nanostructure and are more easily oxidized. The application of EGR increases the agglomeration degree, reduces the graphitization degree and oxidation characteristic temperature, and enhances the oxidation reactivity of particulate. Compared with the particulates collected without EGR, the E a of FT diesel, biodiesel, and diesel particulates are reduced by 36.7%, 41.2%, and 37.5% as the EGR rate is 30%. • Both fuel properties and EGR have a great influence on the particulates. • F-T diesel particles show the higher graphitization degree compared with others. • The using of EGR technology leads to blurry edge of primary particles. • Higher EGR rate leads to stronger oxidation reactivity of particulates. [ABSTRACT FROM AUTHOR]

Tactile sensing requires integrated detection platforms with distributed and highly sensitive haptic sensing capabilities along with biocompatibility, aiming to replicate the physiological functions of the human skin and empower industrial robotic and prosthetic wearers to detect tactile information. In this regard, short peptide-based self-assembled hydrogels show promising potential to act as bioinspired supramolecular substrates for developing tactile sensors showing biocompatibility and biodegradability. However, the intrinsic difficulty to modulate the mechanical properties severely restricts their extensive employment. Herein, by controlling the self-assembly of 9-fluorenylmethoxycarbonyl-modifid diphenylalanine (Fmoc-FF) through introduction of polyethylene glycol diacrylate (PEGDA), wider nanoribbons are achieved by untwisting from well-established thinner nanofibers, and the mechanical properties of the supramolecular hydrogels can be enhanced 10-fold, supplying bioinspired supramolecular encapsulating substrate for tactile sensing. Furthermore, by doping with poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) and 9-fluorenylmethoxycarbonyl-modifid 3,4-dihydroxy-l-phenylalanine (Fmoc-DOPA), the Fmoc-FF self-assembled hydrogels can be engineered to be conductive and adhesive, providing bioinspired sensing units and adhesive layer for tactile sensing applications. Therefore, the integration of these modules results in peptide hydrogelation-based tactile sensors, showing high sensitivity and sustainable responses with intrinsic biocompatibility and biodegradability. The findings establish the feasibility of developing programmable peptide self-assembly with adjustable features for tactile sensing applications., (© 2024 Wiley‐VCH GmbH.)

Hypothesis: The accurate and dynamic manipulation of multiple micro-sized objects has always been a technical challenge in areas of colloid assembly, tissue engineering, and organ regeneration. The hypothesis of this paper is the precise modulation and parallel manipulation of morphology of individual and multiple colloidal multimers can be achieved by customizing acoustic field., Experiments: Herein, we present a colloidal multimer manipulation method by using acoustic tweezers with bisymmetric coherent surface acoustic waves (SAWs), which enables contactless morphology modulation of individual colloidal multimers and patterning arrays by regulating the shape of acoustic field to specific desired distributions with high accuracy. Rapid switching of multimer patterning arrays, morphology modulation of individual multimers, and controllable rotation can be achieved by regulating coherent wave vector configurations and phase relations in real time., Findings: To demonstrate the capabilities of this technology, we have firstly achieved eleven patterns of deterministic morphology switching for single hexamer and precise switching between three array modes. In addition, the assembly of multimers with three kinds of specific widths and controllable rotation of single multimers and arrays were demonstrated from 0 to 22.4 rpm (tetramers). Therefore, this technique enables reversible assembly and dynamic manipulation of particles and/or cells in colloid synthesis applications., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier Inc. All rights reserved.)

Amino acids are the most simplistic bio-building blocks and perform a variety of functions in metabolic activities. Increasing publications report that amino acid-based superstructures present amyloid-like characteristics, arising from their supramolecular β-sheet secondary structures driven by hydrogen-bonding-connected supramolecular β-strands, which are formed by head-to-tail hydrogen bonds between terminal amino and carboxyl groups of the adjacent residues. Therefore, the establishment of the structure-function relationships is critical for exploring the properties and applications of amino acid assemblies. Among the naturally encoded self-assembling amino acids, tyrosine ( Y )-based superstructures have been found to show diverse properties and functions including high rigidity, promoting melanin formations, mood regulations, and preventing anxiety, thus showing promising potential as next-generation functional biomaterials for biomedical and bio-machine interface applications. However, the development of Y -based organizations of functional features is severely limited due to the intrinsic difficulty of modulating the energetically stable supramolecular β-sheet structures. Herein, we report that by the racemic assembly of l- Y and d- Y , the supramolecular secondary structures are modulated from the antiparallel β-sheets in the enantiomeric assemblies to the parallel ones in the racemate counterparts, thus leading to higher degrees of freedom, which finally induce distinct organization kinetics and modulation of the physicochemical properties including the optical shifts, elastic softening, and the piezoelectric outputs of the superstructures.

Biodiesel combustion particulate matter (PM) is different from diesel combustion PM in terms of microscopic morphology, which directly affects the optical properties of PM. To investigate the effect of the microstructure of biodiesel PM on the extinction characteristics, an experiment was performed on a high-pressure common rail diesel engine to collect PM from three kinds of biodiesel (the main raw materials were soybean oil methyl eater (SME), palm oil methyl eater (PME), and waste cooking oil methyl eater (WME), respectively). The particle size distribution, micro morphology, and extinction characteristics of biodiesel PM were analyzed. Results show that combustion biodiesel reduces PM emissions by up to 84.2%. Compared to PM from diesel, biodiesel PM has a smaller particle size and a higher aggregation degree, which results in weaker light absorption capacity. With the iodine number of biodiesel decreasing, the number concentration of biodiesel PM decreases and the fractal dimension increases, which leads to producing a more complex agglomerate and a consequent reduction in extinction coefficient. The average particle sizes of PM from SME, PME, and WME are 5.1%, 6.7%, and 13.9% lower than that of diesel PM. Compared with diesel combustion PM, the peak absorption coefficients of SME, WME, and PME combustion PM decrease by 8.4%, 11.4%, and 13.3%, respectively. The extinction properties of particles decrease with increasing fractal dimension within the wavelength range of visible light., (© 2022. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Acoustic tweezers based on surface acoustic waves (SAWs) have raised great interest in the fields of tissue engineering, targeted therapy, and drug delivery. Generally, the complex structure and array layout design of interdigital electrodes would restrict the applications of acoustic tweezers. Here, we present a novel approach by using bisymmetric coherent acoustic tweezers to modulate the shape of acoustic pressure fields with high flexibility and accuracy. Experimental tests were conducted to perform the precise, contactless, and biocompatible cluster manipulation of polystyrene microparticles and yeast cells. Stripe, dot, quadratic lattice, hexagonal lattice, interleaved stripe, oblique stripe, and many other complex arrays were achieved by real-time modulation of amplitudes and phase relations of coherent SAWs to demonstrate the capability of the device for the cluster manipulation of particles and cells. Furthermore, rapid switching among various arrays, shape regulation, geometric parameter modulation of array units, and directional translation of microparticles and cells were implemented. This study demonstrated a favorable technique for flexible and versatile manipulation and patterning of cells and biomolecules, and it has the advantages of high manipulation accuracy and adjustability, thus it is expected to be utilized in the fields of targeted cellular assembly, biological 3D printing, and targeted release of drugs.

Low-cost and large-area solar-thermal absorbers with superior spectral selectivity and excellent thermal stability are vital for efficient and large-scale solar-thermal conversion applications, such as space heating, desalination, ice mitigation, photothermal catalysis, and concentrating solar power. Few state-of-the-art selective absorbers are qualified for both low- (<200 °C) and high-temperature (>600 °C) applications due to insufficient spectral selectivity or thermal stability over a wide temperature range. Here, a high-performance plasmonic metamaterial selective absorber is developed by facile solution-based processes via assembling an ultrathin (≈120 nm) titanium nitride (TiN) nanoparticle film on a TiN mirror. Enabled by the synergetic in-plane plasmon and out-of-plane Fabry-Pérot resonances, the all-ceramic plasmonic metamaterial simultaneously achieves high, full-spectrum solar absorption (95%), low mid-IR emission (3% at 100 °C), and excellent stability over a temperature range of 100-727 °C, even outperforming most vacuum-deposited absorbers at their specific operating temperatures. The competitive performance of the solution-processed absorber is accompanied by a significant cost reduction compared with vacuum-deposited absorbers. All these merits render it a cost-effective, universal solution to offering high efficiency (89-93%) for both low- and high-temperature solar-thermal applications., (© 2020 Wiley-VCH GmbH.)

External morphology and internal carbonaceous compositions are important characteristics for the source recognition of atmospheric particulate matter (PM). The fractal dimension of morphology and carbon components of diesel PM with different sizes both at high and low load were studied through fractal theory and thermal optical reflection method. It is revealed that small-size PM absorbs more soluble organic fractions and correspondingly has greater box dimension. Due to heavy aggregation, PM collected at low load has greater box dimension than that at high load because of heavy aggregation. OC1, which is the most volatile among organic carbons, is remarkably increased at low load or for small-size PM, absorbing more unburned hydrocarbons. At low load, a large amount of EC1 (char-EC) is generated and the ratio of OC/EC is more than 10, while, at high load, the EC is mainly composed of EC2 (soot-EC) and the ratio of OC/EC is less than 1. Apparently, the box dimension from the morphology of diesel PM presents a positive correlation with the ratio of OC/EC. Via above external and internal characteristics, particulates exhausted from motor vehicles in the atmosphere can be beneficially identified.