Efficient Method Research Articles

A low-cost granular-medium hot quasi-isostatic pressing method for enhancing compressive properties of 3D printed structures

3D printed structures suffered weak bead-to-bead interfacial bonding due to the layer-by-layer manufacturing process. The hot isostatic pressing (HIP) method was effective in improving the micro-structures and enhancing the mechanical properties of 3D printed structures, but it was limited due to the high-cost device and process. Inspired by the HIP method, and aimed at improving the compressive properties of 3D printed thin-walled structures, this work proposed a low-cost granular-medium hot quasi-isostatic pressing (GMHQIP) method realized by the homemade equipment. The hot quasi-isostatic ambient pressure could be produced by pressing the granular medium in the high-temperature environment. The thin-walled structures treated by the GMHQIP method showed a more regular progressive deformation mode than non-treated structures. Compared to the non-treated structure, the specific energy absorption of thin-walled structures treated at 200 °C with 2 MPa for 8 h significantly increased by 170.4 % to the value of 4.95 J/g. The results indicated that the strength and toughness of 3D printed materials improved significantly after the GMHQIP treatment. The interfacial bonding of 3D printed structures was enhanced by using the GMHQIP method. This work offered a low-cost and efficient post-processing method for 3D printed structures to improve compressive properties.

Assembly processes of rhizosphere and phyllosphere bacterial communities in constructed wetlands created via transformation of rice paddies.

Constructed wetlands are an efficient and cost-effective method of restoring degraded wetlands, in which the microorganisms present make a significant contribution to the ecosystem. In this study, we comprehensively investigated the patterns of diversity and assembly processes of 7 types of constructed wetlands at the rhizosphere and phyllosphere levels. The results showed that the rhizosphere communities of the constructed wetlands exhibited a more balanced structure than that of paddy fields, and 5 types of constructed wetland demonstrated higher potential diversity than that of paddy fields. However, the opposite trend was observed for the phyllosphere communities. Analysis of mean nearest taxon difference indicated that both deterministic and stochastic processes affected the establishment of the rhizosphere and phyllosphere communities, and stochastic processes may have had a larger effect. An iCAMP model showed that dispersal limitation was the most important factor (67% relative contribution) in the rhizosphere community, while drift was the most important (47% relative contribution) in the phyllosphere community. Mantel tests suggested that sucrase, average height, top height, total biomass, belowground biomass, maximum water-holding capacity, and capillary porosity were significantly correlated with processes in the rhizosphere community, whereas factors such as the deterministic process, average height, top height, and SOC were significantly correlated with deterministic processes in the phyllosphere community. Our results can assist in the evaluation of artificial restorations, and can provide understanding of the ecological processes of microbial communities, as well as new insights into the manipulation of microorganisms in polluted wetland ecosystems.

Theoretical Study of Efficient Photon-Phonon Resonance Absorption in the Tungsten-Related Vibrational Mode of Scheelite.

Tungsten (W) is an extremely rare and vital metal extensively used in metallurgy, the chemical industry, optoelectronic devices, and machinery manufacturing. In this work, an environmentally friendly and efficient physical method based on photon-phonon resonance absorption (PPRA) is proposed for separating W from scheelite. We calculated the vibrational spectrum of calcium tungstate (CaWO4) and assigned the infrared (IR) absorption and Raman scattering peaks through a dynamic analysis of the normal modes. We focused on the strong IR absorption peaks related to W and identified three high-intensity IR-active modes at around 830 cm-1, corresponding to the stretching of the W-O bonds. Therefore, we propose the use of high-power terahertz (∼25 THz) laser radiation to facilitate W extraction from compounds, leveraging the high efficiency of PPRA. Experimental testing is required to determine the precise absorption frequency under industrial production conditions.

Strip loaded waveguide amplifiers based on erbium-doped nanocomposites with 17 dB internal net gain.

We propose a strip loaded amplifier employing SU-8 as the loaded waveguide and nanoparticles (NPs)-polymethyl methacrylate (PMMA) as the cladding layer. By leveraging the undoped SU-8 loaded waveguide, the polymer waveguide amplifier accomplished remarkably low transmission losses, reaching as low as 1.8 dB/cm at 1530 nm. We prepared NPs-PMMA nanocomposite by utilizing NaLu0.1Y0.7F4: Er3+, Yb3+ @NaLuF4 core-shell nanoparticles, which exhibited a significantly enhanced lifetime of 6.15 ms. An internal net gain of up to 17.7 dB was achieved on a strip loaded waveguide with a length as short as 0.5 cm when the on-chip pump power was 77 mW. Signal enhancement (SE) was measured at different wavelengths, revealing that the strip loaded waveguide exhibited broadband SE ranging from 1510 nm to 1570 nm, covering the C-band. To the best of our knowledge, this work has achieved the highest gain results reported thus far on a polymer matrix and provides an efficient method for optical amplification in passive devices on silicon and Si3N4 platforms, leveraging the ease of integration of polymer materials with diverse photonic platforms.

Metal-Free Synthesis of Trifluoromethyl Carbinol-Containing Imidazo[1,2-a]pyridines via Dehydrative Coupling of Imidazo[1,2-a]pyridines with Trifluoroacetaldehyde

AbstractA facile and efficient method for the synthesis of trifluoromethylated carbinols has been developed from imidazo[1,2-a]pyridines and trifluoroacetaldehyde. The direct C(sp2)–H hydroxytrifluoromethylation is successfully implemented at room temperature using HFIP as solvent through dehydrative cross-coupling process, which displays a broad substrate scope and functional group tolerance. Furthermore, gram-scale and synthetic transformation experiments have also been demonstrated, which indicate its potential applicable values in organic synthesis. This green protocol features operational simplicity, atom economy, mild reaction conditions (e.g., at room temperature, transition-metal- and oxidant-free, without inert gas protection), wide substrate scope, and excellent practicality.

Full three-loop renormalisation of an abelian chiral gauge theory with non-anticommuting γ5 in the BMHV scheme

In this work we present a complete three-loop renormalisation of an abelian chiral gauge theory within the Breitenlohner-Maison/’t Hooft-Veltman (BMHV) scheme of dimensional regularisation (DReg). In this scheme the γ5-matrix appearing in gauge interactions is a non-anticommuting object, leading to a breaking of gauge and BRST invariance. Employing an efficient method based on the quantum action principle, we obtain the complete three-loop counterterm action which serves both to render the theory finite and to restore gauge and BRST invariance. The UV singular counterterms involve not only higher order ϵ-poles but also new counterterm structures emerging at the three-loop level for the first time; the finite symmetry-restoring counterterms are restricted to the same structures as at lower loop orders, just with different coefficients, aligning with our expectations. Both the singular and the finite counterterms include structures which cannot be obtained by the standard multiplicative renormalisation. Our results demonstrate that a rigorous treatment of chiral gauge theories with γ5 defined in the BMHV scheme at the multi-loop level is possible and that the obtained counterterm action is suitable for computer implementations, allowing automated calculations without ambiguities caused by γ5.

Smartphone-assisted ratiometric fluorescence sensor based on NS-codoped carbon dots/Au nanoclusters for rapid detection of Hg2+

Mercury metal can be absorbed into human body through the food chain, and cause considerable harm to human health. Herein, a novel smartphone-enabled ratiometric fluorescence sensing system, which was made up of nitrogen-sulfur co-doped carbon dots (NSCDs) and Au nanoclusters (AuNCs), had developed for rapid detection of mercury ion (Hg2+). The NSCDs/AuNCs displayed dual-emission fluorescence at 406/690 nm. After introducing Hg2+, the fluorescence at 690 nm was obviously quenched, while the signal around 406 nm was slightly attenuated, causing a color change from pink-purple to blue. Under the most suitable conditions, the ratiometric fluorescence probe had two linear ranges of 0.05–3.0 and 3.0–7.0 μM with a low limit of detection (LOD) of 18 nM. The approach was utilized to detect Hg2+ in real water samples. Furthermore, a portable smartphone-assisted sensing platform based on NSCDs/AuNCs provides a simple, affordable, and efficient method for monitoring Hg2+ in the environments and other fields.

Mechanically robust and uniform aramid nanofiber films fabricated using repeated spin-coating and protonation processes

Aramid nanofiber (ANF) films show promise for various industrial applications, but their applicability has been constrained by the low mechanical properties, which are mainly due to their incomplete packing and non-uniform microstructure. This work introduces an efficient method for significantly improving the mechanical properties of ANF films using repeated spin coating and protonation. The method allows for the preparation of ANF films with highly uniform microstructures and adjustable thicknesses while achieving excellent mechanical properties. These ANF films have a Young's modulus of 6.8 GPa, tensile strength of 310 MPa and hardness of 248 MPa, surpassing those produced using previous methods. A comprehensive analysis of the surface and cross-sectional morphologies, chemical composition, thermal stability, and mechanical properties was also carried out to characterize the film properties.

Multiwavelength Excitation in Ho3+-Doped All-Inorganic Double Perovskites Achieved by Codoping Mn2+ for Warm-White LEDs and Plant Growth.

Doping lanthanide ions is an efficient method to modify the optical properties of lead-free double-perovskite halides. However, most lanthanide-doped double perovskites show a low luminescence efficiency and require a high excitation energy. Here, we have successfully prepared a series of Ho3+-doped Cs2NaBiCl6 microcrystals through a simple hydrothermal method and obtained strong characteristic emissions of Ho3+ at 492 and 657 nm under low-energy excitation (449 nm). After codoping Mn2+, apart from the characteristic emissions from Ho3+ under 450 nm wavelength excitation, the orangish-red luminescence consisting of the emission band centered at 591 nm from Mn2+ and a sharp emission peak at 657 nm from Ho3+ is obtained under 355 nm UV light excitation. Photoluminescence (PL) emission and excitation spectra, along with the PL decay curves, confirm the existence of an energy-transfer channel from Cs2NaBiCl6 to Mn2+ and then from Mn2+ to Ho3+. The enhanced absorption efficiency (10.5 → 70.7%) suggests that the codoping of Mn2+ overcomes the low absorption efficiency caused by f-f forbidden transitions of Ho3+. Finally, the diverse luminescent performance within the Cs2NaBiCl6:Ho3+, Mn2+ phosphor is realized by altering the excitation wavelength, thereby enabling its application in warm-white-light-emitting diodes and plant growth in this work.

Green IoT Based on Tropical Weather: The Impact of Energy Harvesting in Wireless Sensor Network

Wireless Sensor Networks (WSNs) are a key component of Green IoT, as they play a critical role in many applications. However, a major challenge faced by WSNs is their limited energy capacity, which can impede their effectiveness. To address this issue, energy harvesting techniques are used to harness ambient energy and power the nodes, eliminating the need for frequent battery replacements or recharging. This study proposes a solar energy harvesting technique to prolong the lifespan of each wireless sensor node in a network. The aim of the research is to assess the impact of energy harvesting on wireless sensor networks with a focus on solar ambient light energy, as it is a critical component of achieving a Green Internet of Things (IoT). The study is adapted to the tropical weather of Malaysia and its forecasted conditions. Through the use of NetSim simulations, the energy efficiency and reliability of the network are evaluated using solar energy harvesting. The recharge rate for energy harvesting in a wireless sensor network is calculated to be 2.34W per day using a 55x70mm solar photovoltaic panel based on Malaysia weather forecasts and sun hours. This proposed method is successfully executed using NetSim, which utilizes real device parameters for a WSN in a simulated agriculture environment. The results show an overall improvement of 22.4 percent in performance parameters in all areas, including energy consumption, network layer, routing performance, and IEEE 802.15.4 metrics, representing a significant improvement. With the implementation of solar energy harvesting, traditional energy of WSNs can benefit from developing smart agricultural monitoring systems. This efficient method and calculation for solar energy harvesting can help to sustain the infinite lifetime of WSN by optimizing the operational time to 18% of the duty cycle. Results demonstrate that the proposed method can effectively increase the energy efficiency and reliability of the network, making it a promising solution for WSNs operating in tropical regions. This research contributes to the development of sustainable and energy-efficient WSNs, promoting the Green IoT concept.

A low-cost vision-based weld-line detection and measurement technique for robotic welding

ABSTRACT To make robotic welding more flexible and intelligent, artificial intelligence-based systems are one of the most important developments. This paper introduces a computer vision-based algorithm for weld path detection, gap measurement, and weld length calculation. The proposed innovative approach employs various image processing techniques and mathematical operations, accurately determining weld attributes at seam points. Using the YOLO-based object detection algorithm, the model attains a remarkable average precision of 99.5% in identifying atypical weld regions. The study also introduces an efficient boundary line elimination method based on the Probabilistic Hough transform and mathematical logic. Methodology for classifying weld lines with or without significant gaps has been proposed, followed by adapting distinct set of algorithms for weld line identification and gap measurement. Rigorous testing on butt joints of diverse shapes (e.g., straight, zig-zag, and curve) and sizes verifies the robustness of the algorithm, with errors well within ±1 mm for length measurements. In testing conducted at three different points along the individual weld profile, the maximum error in estimating the weld gap was observed to be 0.11 mm. Weld seam information can be extracted effectively with the proposed algorithm, which proves its viability for industrial applications.

UViT: Efficient and lightweight U-shaped hybrid vision transformer for human pose estimation

Pose estimation plays a crucial role in human-centered vision applications and has advanced significantly in recent years. However, prevailing approaches use extremely complex structural designs for obtaining high scores on the benchmark dataset, hampering edge device applications. In this study, an efficient and lightweight human pose estimation problem is investigated. Enhancements are made to the context enhancement module of the U-shaped structure to improve the multi-scale local modeling capability. With a transformer structure, a lightweight transformer block was designed to enhance the local feature extraction and global modeling ability. Finally, a lightweight pose estimation network— U-shaped Hybrid Vision Transformer, UViT— was developed. The minimal network UViT-T achieved a 3.9% improvement in AP scores on the COCO validation set with fewer model parameters and computational complexity compared with the best-performing V2 version of the MobileNet series. Specifically, with an input size of 384×288, UViT-T achieves an impressive AP score of 70.2 on the COCO test-dev set, with only 1.52 M parameters and 2.32 GFLOPs. The inference speed is approximately twice that of general-purpose networks. This study provides an efficient and lightweight design idea and method for the human pose estimation task and provides theoretical support for its deployment on edge devices.

Enzymatic synthesis of structured lipids from sacha inchi (Plukenetia volubilis) oil with capric acid via acidolysis reaction in stirred tank and packed bed mini reactors

The present study describes an efficient and sustainable synthesis method for producing functional triglycerides (FTs) by conducting an acidolysis reaction of sacha inchi (Plukenetia volubilis) oil with capric acid (C10), catalyzed by Rhizopus oryzae (RO) lipase immobilized in low-cost corn cob powder, to obtain medium-large-medium chain (MLM) triglycerides. Initially, acidolysis reactions were performed between sacha inchi oil, C10, and the immobilized enzyme in a stirred tank at various temperatures (35 °C, 45 °C, 55 °C, and 59 °C), different molar ratios (1:2, 1:3, 1:4 oil:fatty acid), and various hydrolytic enzyme activities (83.6, 124, and 217 IU/mg). Subsequently, to optimize the degree of incorporation, the best condition from the stirred tank reactions (45 °C, 1:3 M ratio, and 217 U of hydrolytic activity) was selected, considering the highest nutritional quality of the lipid in terms of the migration of the sn2 position, and was tested in a packed bed reactor with a spatial time of 112 min, residence time of 107 min, and a flow rate of 0.5 mL/min. The highest incorporation degree achieved in packed bed reactor was 36% at 45 °C. Afterward, it was developed for the best condition an integrative platform for the recycling of the RO lipase immobilized in low-cost corn cob powder (up to four successive cycles without any make up). Subsequent assays on the functional triglycerides revealed atherogenic and thrombogenicity lipid index values of 0.04 ± 0.10 and 4.15 ± 0.05, respectively, which were lower than those of pure sacha inchi oil, indicating the potential to enhance the nutritional quality of the oil through C10 incorporation.

An efficient and precise stability analysis method for milling process

An efficient and precise stability analysis method for milling process

Enantioselective Reduction of Noncovalent Complexes of Amino Acids with CuII via Resonant Collision-Induced Dissociation: Collision Energy, Activation Duration Effects, and RRKM Modeling.

Formation of noncovalent complexes is one of the approaches to perform chiral analysis with mass spectrometry. Enantiomeric distinction of amino acids (AAs) based on the relative rate constants of competitive fragmentations of quaternary copper complexes is an efficient method for chiral differentiation. Here, we studied the complex [CuII,(Phe,PhG,Pro-H)]+ (m/z 493) under resonant collision-induced dissociation conditions while varying the activation time. The precursor ion can yield two main fragments through the loss of the non-natural AA phenylglycine (PhG): the expected product ion [CuII,(Phe,Pro-H)]+ (m/z 342) and the reduced product ion [CuI,(Phe,Pro)]+ (m/z 343). Enantioselective reduction describes the difference in relative abundance of these ions, which depends on the chirality of the precursor ion: the formation of the reduced ion m/z 343 is favored in homochiral complexes (DDD) compared to heterochiral complexes (such as LDD). Energy-resolved mass spectrometry data show that reduction, which arises from rearrangement, is favored at a low collision energy (CE) and long activation time (ActT), whereas direct cleavage preferentially occurs at a high CE and short ActT. These results were confirmed with kinetic modeling based on RRKM theory. For this modeling, it was necessary to set a pre-exponential factor as a reference, so that the E0 values obtained are relative values. Interestingly, these simulations showed that the critical energy E0 required to form the reduced ion is comparable in both homochiral and heterochiral complexes. However, the formation of product ion m/z 342 through direct cleavage is associated with a lower E0 in heterochiral complexes. Consequently, enantioselectivity would not be caused by enhanced reduction in homochiral complexes but rather by direct cleavage being favored in heterochiral complexes.

Constrained Plug-and-Play Priors for Image Restoration.

The Plug-and-Play framework has demonstrated that a denoiser can implicitly serve as the image prior for model-based methods for solving various inverse problems such as image restoration tasks. This characteristic enables the integration of the flexibility of model-based methods with the effectiveness of learning-based denoisers. However, the regularization strength induced by denoisers in the traditional Plug-and-Play framework lacks a physical interpretation, necessitating demanding parameter tuning. This paper addresses this issue by introducing the Constrained Plug-and-Play (CPnP) method, which reformulates the traditional PnP as a constrained optimization problem. In this formulation, the regularization parameter directly corresponds to the amount of noise in the measurements. The solution to the constrained problem is obtained through the design of an efficient method based on the Alternating Direction Method of Multipliers (ADMM). Our experiments demonstrate that CPnP outperforms competing methods in terms of stability and robustness while also achieving competitive performance for image quality.

Ortho‐C−H Methylation and Ipso‐C−O Alkenylation of Aryl Triflates via Catellani Strategy

AbstractThe ortho C−H methylation and ipso C−O alkenylation of aryl triflates was regio‐selectively achieved in one pot by palladium/norbornene (NBE) synergistic catalysis. This work provides an efficient method for preparing poly‐substituted aromatics with (deuterated) methyl and alkenyl groups from the readily available phenoxides.

Enantioselective Synthesis of C2-Quaternary Indolin-3-ones by Pt-Catalyzed Alkynylation of 2-Aryl-3H-indol-3-one with Alkynylsilanes.

An efficient method for the synthesis of five-membered chiral propargylic amines from 2-aryl-3H-indol-3-one and alkynylsilanes has been developed. The reaction proceeded under the catalytic system of PtCl4, oxazoline-based ligand L11, Zn(CF3COO)2, and AcOH in DCE at 95 °C via in situ desilylation of TMS-alkynes. This methodology also highlights a new protocol for the in situ desilylation of alkynylsilanes. The reaction showed a broad substrate scope with good yields and enantioselectivity.

Numerical modelling of vibratory extraction of monopiles from clayey seabed

Understanding and optimizing the extraction of offshore monopiles from the seabed in decommissioning operations give both environmental benefits and cost reduction. The literature highlights the significance of utilizing a vibratory hammer for the complete removal of monopiles in granular or non-cohesive seabed, e.g., sandy soil, offering a cost-effective alternative to the conventional cutting method. However, the available knowledge for applying this method to cohesive soil is limited. The present study examines vibratory pile extraction from cohesive soil, for both soft and stiff clays, with the aim of assessing the resulting extraction force required for pile removal. Coupled Eulerian-Lagrangian (CEL) analyses with two domains of pile and soil are performed using the finite element package ABAQUS. A modified Mohr-Coulomb (MCC) soil model is coded into a VUSDFLD subroutine to properly simulate the soil softening and shear strain rate dependency of seabed soil in an Eulerian domain. The importance of shear strain and softening effects is underscored for soft clay by demonstrating an approximately 20% reduction in the force needed to initiate cyclic extraction of the monopile compared to scenarios where these effects are not included. However, incorporating these effects does not affect the behavior of stiff clay. The present numerical findings show that adopting vibratory extraction method leads to more soil resistance in cohesive soils at the beginning of the extraction. Considering the added weight og the vibratory hammer which should be clamped to the monopile top head leads to exceedance of the required force than the one required for removal of the monopile without vibration (i.e., the pulling-out method). This demonstrates that the vibratory extraction method is not an efficient method for monopile extraction from clayey seabed despite its beneficial effects reported in the literature for sandy soil.

Iron-Catalyzed C(sp3)-C(sp3) Coupling to Construct Quaternary Carbon Centers.

The construction of quaternary carbon centers via C-C coupling protocols remains challenging. The coupling of tertiary C(sp3) with secondary or tertiary C(sp3) counterparts has been hindered by pronounced steric clashes and many side reactions. Herein, we have successfully developed a type of bisphosphine ligand iron complex-catalyzed coupling reactions of tertiary alkyl halides with secondary alkyl zinc reagents and efficiently realized the coupling reaction between tertiary C(sp3) and secondary C(sp3) with high selectivity for the initial instance, which provided an efficient method for the construction of quaternary carbon centers with high steric hindrance. The combination of an iron catalyst and directing group of the substrate makes the great challenging transformation possible.