Multilayer Pattern Research Articles

Roman wall paintings from the Roman Forum district of Carthago Nova: Characterisation of mortars and pigments

This paper aims to study the construction technique and characterisation of original mortars and wall paintings at the Roman Forum district of Carthago Nova (Spain). A multi-analytical approach was conducted on original fragments using Optical Microscopy (OM), Field Emission Scanning Electron Microscopy (FESEM), colour tests (CIE L*a*b*) and contact angle measurements. Besides, the chemical composition was studied by X-fluorescence (XRF), Thermogravimetry (TG), X-ray diffraction (XRD) and Infrared spectroscopy using attenuated total reflectance (ATR-FTIR). The mortars showed a multi-layered pattern consisting of three distinguishable layers that were decorated with low-thickness coatings. The top layer composition was eminently calcitic, while the central and bottom layers were probably elaborated with pozzolanic materials. It is worth noting that unusual minerals as cerussite (PbCO3) were identified in some layers, and probably associated to subsequent activities carried out in the site after Roman times. The top coating was made of hematite (Fe2O3) for red decoration, whereas graphite (C) and hydroxyapatite (Ca5(PO4)3(OH)) were identified in black coatings, which suggests the use of animal bones in the production of black pigments. In addition, the outer surface of some fragments was most likely coated with organic substances to enhance colour and durability. Finally, SEM examination and EDX analyses also confirmed some of the above findings and the existence of NaCl surface crusts due to natural weathering.

Generalized complex variable analysis of shallow tunneling through multi-layered ground

The mechanical analysis of shallow tunnels crossing multiple ground layers is a common problem in urban underground engineering. Since the tunnel boundary intersects multiple ground layers, the challenges of mixed boundary value problem for composite boundary and the conformal mapping of irregular banding computational domain are faced in solving the multi-boundary problem. For this, a new solution strategy regarding the generalized complex variable method to calculate the mechanical responses of the multi-layered ground is proposed. The research object is divided into two independent objects including the complete multi-layered ground without tunnel and the complete tunnel boundary. Firstly, the mechanical responses of the complete multi-layered ground are solved through the superposition of multiple single-boundary contributions. Subsequently, the virtual boundary circle and its corresponding analytic functions are introduced in analyzing the tunnel boundary contribution. Finally, the solution for the stress and displacement field of the multi-layered ground is modified by superimposing the contribution of the virtual boundary circle, so that all the given boundary conditions are satisfied. The self-consistency and accuracy of the proposed method are validated by several examples. The characteristics of the displacement propagation of typical multi-layered ground patterns are analyzed based on the analytical solution. The proposed method can be used to analyze the mechanical responses of multi-layered ground with arbitrary intersections between the tunnel and ground boundaries.

Bio-inspired soft pneumatic actuator based on a kresling-like pattern with a rigid skeleton

IntroductionBiomimetic soft pneumatic actuators (SPA) with Kresling origami patterns have unique advantages over conventional rigid robots, owing to their adaptability and safety. ObjectivesInspired by cloning and moving behaviors observed from salps, we proposed an SPA based on a Kresling-like pattern with a rigid skeleton. The elongation and output force were tested, and the effectiveness of the applications with the SPA was evaluated. MethodsThe proposed SPA consists of rigid skeletons and a soft skin. The rigid skeletons are constructed using layers of Kresling-like patterns, while a novel extensible inserting structure is devised to replace the folds found in conventional Kresling patterns. This innovative approach ensures that the SPA exhibits axial contraction/expansion motion without any twisting movement. To mimic the bionic characteristics of swimming and ingesting progress of salps, the proposed SPA can perform an axial contraction motion without twisting and a controllable bending motion based on multi-layered Kresling-like patterns; to mimic the cloning and releasing life phenomena of salps, the number of layers of Kresling-like patterns is changeable by adding or reducing skeleton components according to the practical needs. ResultsThe experimental elongation results on the SPA with multiple layers of Kresling-like patterns show that the elongation can increase to above 162% by adding layers; the experimental output force results show that the three-layer SPA can provide 6.36 N output force at an air flow rate of 10 L/min, and the output force will continue to increase as the number of layers of Kresling-like pattern increases or the air flow rate increases. Further, we demonstrate the applications of the SPA in soft grippers, scissor grippers, claw grippers and pipe crawlers. ConclusionOur proposed SPA can avoid twisting in the radial contraction motion with high elongation and output force, and provide the practical guidance for bio-inspired soft robotic applications.

POS-GIFT: A geometric and intensity-invariant feature transformation for multimodal images

Multimodal image matching suffers from severe geometric and nonlinear intensity distortion (NID). Towards this problem, we propose a multimodal image matching algorithm based on multi-orientation filtering results, called position-orientation-scale guided geometric and intensity-invariant feature transformation (POS-GIFT). First, we design a multi-layer circular point sampling pattern to effectively capture the local image structure. Then, we propose a novel feature descriptor that can work robustly across rotational differences in [0°, 360°) in the presence of NID. Specifically, we (1) integrate the multi-orientation filtering response in the local neighborhood with a Gaussian weight to form the feature of each sampled point (GFP), (2) build feature vectors for each orientation by concatenating the features of points grouped by orientation, (3) estimate the primary orientation by finding the feature vector with the largest norm which is constructed in the previous step, (4) modify the order of elements of GFP, and (5) finally concatenate the features of all sampled points in a certain order to form the complete feature descriptor. At last, we propose a position-orientation-scale guided inlier recovery strategy (POS) by integrating the global position, orientation, and scale information to further improve the matching performance, especially the number and distribution of correct matches in texture-less and complex areas. Experimental results on various multimodal datasets from remote sensing, medical, and computer vision imaging domains show that POS-GIFT outperforms eight state-of-the-art multimodal image feature matching algorithms which are five handcrafted-based methods, OS-SIFT, PSO-SIFT, LGHD, RIFT, and LNIFT, and three learning-based methods RedFeat, MatchFormer, and SemLA by several times in terms of correct matches while improving the root-mean-square error to around 1 pixel. Our implementation is available at https://github.com/Zhuolu-Hou/POS-GIFT.

Multi-constraint spatial coupling for the body joint quadruped robot and the CPG control method on rough terrain

Quadruped robots have frequently appeared in various situations, including wilderness rescue, planetary exploration, and nuclear power facility maintenance. The quadruped robot with an active body joint has better environmental adaptability than one without body joints. However, it is difficult to guarantee the stability of the body joint quadruped robot when walking on rough terrain. Given the above issues, this paper proposed a gait control method for the body joint quadruped robot based on multi-constraint spatial coupling (MCSC) algorithm. The body workspace of the robot is divided into three subspaces, which are solved for different gaits, and then coupled to obtain the stable workspace of the body. A multi-layer central pattern generator model based on the Hopf oscillator is built to realize the generation and switching of walk and trot gaits. Then, combined with the MCSC area of the body, the reflex adjustment strategy on different terrains is established to adjust the body’s posture in real time and realize the robot’s stable locomotion. Finally, the robot prototype is developed to verify the effectiveness of the control method. The simulation and experiment results show that the proposed method can reduce the offset of the swing legs and the fluctuation of the body attitude angle. Furthermore, the quadruped robot is ensured to maintain stability by dynamically modifying its body posture. The relevant result can offer a helpful reference for the control of quadruped robots in complex environments.

Ultrathin, Flexible, and Reusable Silicon Shadow Masks Manipulated via Transfer Printing

Stencil lithography is a facile patterning technique that offers a potential solution to the limitations of conventional photolithography. However, several critical factors such as enhanced pattern resolution, ability to pattern on nonplanar surfaces, and multilayer patterning should further be addressed to extend the applications of stencil lithography. This study presents a novel ultrathin silicon shadow mask which is flexible, reusable, and able to be precisely aligned and manipulated through transfer printing. The small thickness of the silicon shadow mask inherently provides it with the enhanced resolution patterning on both planar and nonplanar surfaces. To highlight these attractive benefits, substrates are patterned with metal deposition as well as by etching in a multilayer configuration. Moreover, it is found that the pattern resolution which is degraded as the shadow mask is repeatedly coated with metal and becomes warped can be restored after the mask cleaning procedure, demonstrating its effective reusability. Finally, as a device‐level application, top contact/bottom gate organic thin film transistor arrays are fabricated on both planar and curved surfaces using the shadow mask. These results show the promise of stencil lithography as a versatile and reliable high resolution patterning method for various applications by exploiting the presented ultrathin silicon shadow mask.

Inkjet-printed morphogenesis of tumor-stroma interface using bi-cellular bioinks of collagen-poly(N-isopropyl acrylamide-co-methyl methacrylate) mixture

Recent advances in biomaterials and 3D printing/culture methods enable various tissue-engineered tumor models. However, it is still challenging to achieve native tumor-like characteristics due to lower cell density than native tissues and prolonged culture duration for maturation. Here, we report a new method to create tumoroids with a mechanically active tumor-stroma interface at extremely high cell density. This method, named “inkjet-printed morphogenesis” (iPM) of the tumor-stroma interface, is based on a hypothesis that cellular contractile force can significantly remodel the cell-laden polymer matrix to form densely-packed tissue-like constructs. Thus, differential cell-derived compaction of tumor cells and cancer-associated fibroblasts (CAFs) can be used to build a mechanically active tumor-stroma interface. In this methods, two kinds of bioinks are prepared, in which tumor cells and CAFs are suspended respectively in the mixture of collagen and poly (N-isopropyl acrylamide-co-methyl methacrylate) solution. These two cellular inks are inkjet-printed in multi-line or multi-layer patterns. As a result of cell-derived compaction, the resulting structure forms tumoroids with mechanically active tumor-stroma interface at extremely high cell density. We further test our working hypothesis that the morphogenesis can be controlled by manipulating the force balance between cellular contractile force and matrix stiffness. Furthermore, this new concept of “morphogenetic printing” is demonstrated to create more complex structures beyond current 3D bioprinting techniques.

Low-RCS Transmitarray Based on 2.5-D Cross-Polarization Converter

This paper presents a low radar cross section (RCS) transmitarray with absorption-transmission-absorption frequency response. In contrast to conventional transmitarrays based on multi-layer metallic patterns, a 2.5-dimensional cross polarization converter is employed to provide a large phase shifting range of high transmission efficiency. A benchmark transmitarray composed of the polarizer element with an aperture thickness of 2.3 mm (0.08λ) is designed to achieve a focused radiation beam. As a result, its peak gain is 22.1 dB and maximum aperture efficiency is 57.6%. Next, a low-RCS transmitarray is designed by introducing a lossy layer to absorb the out-of-band incident waves. Compared with the benchmark antenna, the radiation performance of the low-RCS transmitarray is maintained with a peak gain of 21.7 dB and maximum aperture efficiency of 53.7%. Meanwhile, dual-polarized significant RCS reduction can be obtained at both lower and higher frequencies.

Invisible Legacies and Rural/Urban Dynamics in Heritagization Process of Soviet-Era Collective Farm Buildings

ABSTRACT This article concentrates on the role of social and spatial processes that influence how architectural sites of the past are deemed part of the cultural heritage. It will focus on the contested architecture of collective farms in post-Soviet Estonia. By analyzing urban–rural dynamics and mnemonic processes dealing with controversial historical periods, it will demonstrate the complex negotiations that are involved in heritagization processes. These complicated processes are illustrated by analyzing three case studies, which show how heritagization is a heterogeneous practice, negotiated on multiple levels in communities, on the collective and private levels, but also between the state and the private sector. The article argues that rural/urban representation and relational dynamics play an important role in heritagization processes. Though the collective-farm architecture was built during the ideologically contested Soviet period, the attitudes towards these premises are intertwined with multi-layered patterns of remembering, which are embedded in local social relations and community identity.

Large-area photo-patterning of initially conductive EGaIn particle-assembled film for soft electronics

Eutectic-gallium-indium particle (EGaIn*) is considered one of the promising conducting materials for soft electronics due to its enhanced stability compare to bulk EGaIn and constant conductance under strain. However, its practical implementation has thus far been limited due to the challenges of achieving initial electrical conductivity and the incompatibility with well-developed fabrication strategies. Here, we report materials and manufacturing methods that allow large-area multi-layered patterning of ‘polystyrene sulfonate (PSS)-attached EGaIn* (EGaIn*:PSS)’ thin-film with the conventional cleanroom process. PSS enhances the stability of EGaIn*, which allow uniform thin-film coating and photographic lift-off at a wafer-scale down to 10 μm features of varying thicknesses. Using dimethyl sulfoxide as the solvent during lift-off induces cohesion between EGaIn*:PSS, resulting in initial electrical conductivity without an additional activation process. Demonstrations of stretchable display, multilayer pressure sensing systems, and soft artificial finger validate the versatility and reliability of this manufacturing strategy for soft electronics.

Colourful 3D anti-counterfeiting label using nanoscale additive manufacturing

ABSTRACT Microprinting is changing anti-counterfeit technology by producing complex micro-/nano-scale labels to increase the security level. However, the current microprinted anti-counterfeiting labels only contain 2D features, thought of as single coding (e.g. mostly in texts or graphs), unable to satisfy the high-end anti-counterfeiting demands of producing multi-coding, high-storage-density labels. Here, we introduce an approach for fluorescence printing to produce a 3D colourful, sophisticated anti-counterfeiting label. In the method, pre-synthetic QDs are printed with photoresists based on two-photon polymerisation, allowing for accurate regulation of fluorescence in both 2D and 3D. The fabricated photoresists exhibit immediate and postprocessing-free colour emissions under UV light. We demonstrated the ultra-high free design and accurate manufacturing capability of the approach by fabricating multi-colour, multi-layer patterns containing both texts and graphs on a 50μm × 50μm × 30μm portable label. The approach can also be applied to multi-dimensional optical data storage and colourful microdisplays.

A Novel Pulsed Stimulation Pattern in Spinal Cord Stimulation: Clinical Results and Postulated Mechanisms of Action in the Treatment of Chronic Low Back and Leg Pain

ObjectivesThe aim of this article is to discuss the possible mechanisms of action (MOAs) and results of a pilot study of a novel, anatomically placed, and paresthesia-independent, neurostimulation waveform for the management of chronic intractable pain. Materials and MethodsA novel, multilayered pulsed stimulation pattern (PSP) that comprises three temporal layers, a Pulse Pattern layer, Train layer, and Dosage layer, was developed for the treatment of chronic intractable pain. During preliminary development, the utility was evaluated of anatomical PSP (aPSP) in human subjects with chronic intractable pain of the leg(s) and/or low back, compared with that of traditional spinal cord stimulation (T-SCS) and physiological PSP. The scientific theory and testing presented in this article provide the preliminary justification for the potential MOAs by which PSP may operate. ResultsDuring the pilot study, aPSP (n = 31) yielded a greater decrease in both back and leg pain than did T-SCS (back: −60% vs −46%; legs: −63% vs −43%). In addition, aPSP yielded higher responder rates for both back and leg pain than did T-SCS (61% vs 48% and 78% vs 50%, respectively). DiscussionThe novel, multilayered approach of PSP may provide multimechanistic therapeutic relief through preferential fiber activation in the dorsal column, optimization of the neural onset response, and use of both the medial and lateral pathway through the thalamic nuclei. The results of the pilot study presented here suggest a robust responder rate, with several subjects (five subjects with back pain and three subjects with leg pain) achieving complete relief from PSP during the acute follow-up period. These clinical findings suggest PSP may provide a multimechanistic, anatomical, and clinically effective management for intractable chronic pain. Because of the limited sample size of clinical data, further testing and long-term clinical assessments are warranted to confirm these preliminary findings.

Formation of a 3D Particle Array Actuated by Ultrasonic Traveling Waves in a Regular Polygon Resonator.

Acoustic radiation forces have been extensively studied regarding static particles, cell patterning, and dynamic transportation. Compared with standing wave manipulation, traveling wave manipulation can be more easily modulated in real time and has no matching requirement between the size of the resonant cavity and the sound frequency. In this work, we present an efficient, multi-layer microparticle pattern technique in a 3D polygon cavity with a traveling bulk acoustic wave. There are two types of excitation modes: the interval excitation mode (IEM) and the adjacent excitation mode (AEM). We conducted theoretical and simulation analyses, and our results show that both of these modes can form particle arrays in the resonant cavity, which is in accordance with the experimental results. The array spacings in the IEM and AEM were about 0.8 mm and 1.3 mm, respectively, while the acoustic frequency was 1MHz. Double-layer particle patterns were arrayed by a double in the resonant cavity. The spacing between the two layers was set at 3.0 mm. The line spacings were about 0.4 mm in both layers. The line width was 0.2 mm, which was larger than the single layer. The results show that ultrasonic traveling waves are a feasible method to manipulate particles and cells that form 3D patterns in particle-fluid flows.

Large refrigerant capacity in superparamagnetic iron nanoparticles embedded in a thin film matrix

A magnetocaloric effect (MCE) with sizable isothermal entropy change (ΔS) maintained over a broad range of temperatures above the blocking temperature is reported for a rare earth-free superparamagnetic nanoparticle system comprising of Fe–TiN heterostructure. Superparamagnetic iron (Fe) particles were embedded in a titanium nitride (TiN) thin film matrix in a TiN/Fe/TiN multilayered pattern using a pulsed laser deposition method. High angle annular dark-field images in conjunction with dispersive energy analysis, recorded using scanning transmission electron microscopy, show a clear presence of alternating layers of Fe and TiN with a distinct atomic number contrast between Fe particles and TiN. Quantitative information about the isothermal entropy change (ΔS) and the magnetocaloric effect in the multilayer Fe–TiN system has been obtained by applying Maxwell relation to the magnetization vs temperature data at various fields. With the absence of a dynamic magnetic hysteresis above the blocking temperature, the negative ΔS as high as 4.18 × 103 J/Km3 (normal or forward MCE) is obtained at 3 T at 300 K.

Achieving highly anisotropic thermal and electrical conductivities via synergistic distribution of boron nitride and graphene nanosheets in multilayered composites

It has long been a challenging problem to fabricate polymeric composites that could combine high thermal conductivity, electrical insulating and anti-static capacity. Dirven by the fascinating features of multilayer structure in nature, here we report a series of multilayered boron nitride/graphene nanoplate (BN/GNP) composites by virtue of a sequentially layered assembly strategy, which is realized through unidirectional freezing drying followed by alternative compression molding. Due to the high orientation state, as well as the synergistic distribution of BN and GNP in multilayered pattern, the compositing BN/GNP film with optimized filler content displays a satisfying in-plane thermal conductivity of 21.9 W m−1 K−1, which is 6161 % and 669 % higher than that of pure CS and isotropic composite, respectively. Meanwhile, the qualification of such compositing film in factual dissipation of exhaust heat generated by complex electronic devices is further explored and demonstrated. Moreover, such compositing film possesses distinct anisotropic electrical performance, which could simultaneously satisfy the requirement of through-plane insulating and in-plane antistatic property. Given such superior performance, as well as the green and facile process, such work is believed to further inspire the design and fabrication of intelligent electronic device with excellent heat dissipation capacity.

IoT-based urban agriculture container farm design and implementation for localized produce supply

With increasing population in cities, urban agriculture has been proposed as a solution for sustainable urban development and food security improvement. In this application note, as an attempt at small-scale controlled environment agriculture, a container farm was constructed to provide an anniversary localized fresh produce supply in urban areas. The constructed container farm adopted a multi-layer cultivation pattern with artificially controlled environment for maximizing revenue in limited urban vacant areas available. Considering requirements of efficient management, an internet of things (IoT) management system was designed to monitor and control environment of this container farm remotely and on-site. As a case study, the container farm was placed in an outdoor parking space for urban agriculture application with mushrooms as trial crop. The cultivation experimental results have shown that internal microclimate of the constructed container farm have presented the characteristics of long-term stability with short-term changes while the IoT system provided reliable production data collection.

WGDI: A user-friendly toolkit for evolutionary analyses of whole-genome duplications and ancestral karyotypes

Evidence of whole-genome duplications (WGDs) and subsequent karyotype changes has been detected in most major lineages of living organisms on Earth. To clarify the complex resulting multi-layered patterns of gene collinearity in genome analyses, there is a need for convenient and accurate toolkits. To meet this need, we developed WGDI (Whole-Genome Duplication Integrated analysis), a Python-based command-line tool that facilitates comprehensive analysis of recursive polyploidization events and cross-species genome alignments. WGDI supports three main workflows (polyploid inference, hierarchical inference of genomic homology, and ancestral chromosome karyotyping) that can improve the detection of WGD and characterization of WGD-related events based on high-quality chromosome-level genomes. Significantly, it can extract complete synteny blocks and facilitate reconstruction of detailed karyotype evolution. This toolkit is freely available at GitHub (https://github.com/SunPengChuan/wgdi). As an example of its application, WGDI convincingly clarified karyotype evolution in Aquilegia coerulea and Vitis vinifera following WGDs and rejected the hypothesis that Aquilegia contributed as a parental lineage to the allopolyploid origin of core dicots.

Synthesis of a Novel Adsorbing Agent by Coupling Chitosan, β-Cyclodextrin, and Cerium Dioxide: Evaluation of Hexavalent Chromium Removal Efficacy from Aqueous Solutions

The present study aimed at synthesizing a novel adsorbing agent by coupling chitosan, β-cyclodextrin, and cerium dioxide (Chit/β-CyD/Ce). Its efficiency towards the removal of hexavalent chromium from aqueous solutions was studied and compared to an adsorbent comprising of only chitosan and cerium dioxide. Batch water purification experiments in varying experimental conditions (initial adsorbent concentration 5–100 mg/L, adsorbate concentration 0.1–2 g/L, pH 2–11, and temperature 15–50 °C) were carried out to evaluate the effectiveness of both adsorbents. In all the experimental cases, the Chit/β-CyD/Ce adsorbent exhibited the higher efficacy. The optimum operating conditions were found to be at an initial adsorbent concentration of 2 g/L, pH = 3, and temperature of 50 °C, with the Chit/β-CyD/Ce adsorbent being able to fully remove Cr(VI) from solutions with up to 50 mg/L Cr(VI) at these conditions. The adsorption of hexavalent chromium onto both adsorbents occurs in a multilayer pattern of a heterogeneous surface following the Freundlich isotherm model. Furthermore, the adsorption process was exothermic and obeyed the pseudo-second-order kinetic model, thus indicating the occurrence of chemisorption. Finally, FTIR, XRD, and SEM analyses were performed to characterize the synthesized adsorbents and verify the adsorption process.

Fabrication of Multilayer Molds by Dry Film Photoresist.

Dry film photoresists are widely employed to fabricate high-aspect-ratio microstructures, such as molds for microfluidic devices. Unlike liquid resists, such as SU-8, dry films do not require a cleanroom facility, and it is straightforward to prepare uniform and reproducible films as thick as 500 µm. Multilayer patterning, however, can be problematic with dry film resists even though it is critical for a number of microfluidic devices. Layer-to-layer mask alignment typically requires the first layer to be fully developed, making the pattern visible, before applying and patterning the second layer. While a liquid resist can flow over the topography of previous layers, this is not the case with dry film lamination. We found that post-exposure baking of dry film photoresists can preserve a flat topography while revealing an image of the patterned features that is suitable for alignment to the next layer. We demonstrate the use of this technique with two different types of dry film resist to fabricate master molds for a hydrophoresis size-sorting device and a cell chemotaxis device.

Transport of emerging organic ultraviolet (UV) filters in ceramic membranes: Role of polyethylene (PE) microplastics

Microplastics can be considered potential carriers of emerging organic ultraviolet (UV) filters due to their considerable adsorption capacity in wastewater treatment. The adsorption behavior of organic UV filters, which are commonly contained in personal care products to preserve the skin against UV radiation, onto polyethylene (PE) microplastics were systematically studied to investigate their combined effects. Kinetics and isotherm analyses revealed that the adsorption of four organic UV filters onto PE microplastic surfaces followed a multi-rate and a heterogeneous multi-layer pattern. Several factors including salinity, microplastic size, and dosage also influenced the adsorption efficiency due to hydrophobic interactions. A bench-scale cross-flow ceramic membrane filtration experiment was investigated to evaluate the role of PE microplastics on the retention performance of organic UV filters. The retentions for organic UV filters were 34.2%–37.8% in the non-existence of PE microplastics. Conversely, organic UV filter retentions were significantly increased up to 82.2%–97.9% when they were adsorbed onto the PE microplastics, which were almost completely retained by the ceramic membrane. Therefore, organic UV filters can likely migrate and eventually be carried by PE microplastics, thus increasing the retention of both emerging organic UV filters and microplastics prior to discharge from wastewater treatment facilities.