Simple Construction Research Articles

Electrospinning of photoluminescent-magnetic GdF3:Tb3+,Sm3+@SiO2 belt-in-belt structured nanoribbons with tunable fluorescence and energy transfer

A novel strategy has been devised to synthesize directly GdF3:Tb3+,Sm3+@SiO2 belt-in-belt structured nanoribbons by uniaxial electrospinning technique and subsequent fluorination approach. GdF3:Tb3+,Sm3+@SiO2 belt-in-belt structured nanoribbons with sheathed ribbon structure have large specific surface area and unique void space structure between the inner and outer ribbons, which enables materials possess extraordinary applications in cancer therapy, drug delivery, sensors, catalysis, etc. The average widths of the inner and outer layers of the GdF3:Tb3+,Sm3+@SiO2 belt-in-belt structured nanoribbons are 1.60 ± 0.03 μm and 1.87 ± 0.02 μm, respectively. Furthermore, GdF3:1%Tb3+,x%Sm3+@SiO2 and GdF3:y%Tb3+,2%Sm3+@SiO2 belt-in-belt structured nanoribbons (x = 0.5, 1, 2, 3, 4, 5; y = 0.1, 0.3, 0.5, 0.7, 1, 2) have also been successfully constructed to observe energy transfer phenomenon and tunable changes in light color. Energy transfer from Tb3+ ions to Sm3+ ions has been proved according to the measured luminescence spectra of the samples. More importantly, Tb3+, Sm3+ co-doped GdF3@SiO2 belt-in-belt structured nanoribbons simultaneously exhibit multicolor luminescent and paramagnetic dual functional performances owing to the natural magnetic moment of Gd3+ ions, making materials have potential applications in flat-panel displays, lasers, biomarkers, and magnetic resonance imaging. In this work, a novel and high-efficient approach is presented to construct photoluminescence-magnetism dual functional GdF3:Tb3+,Sm3+@SiO2 belt-in-belt structured nanoribbons, providing theoretical basis and technical guidance for the simple construction of other nanomaterials with special structures.

NiCo2O4/Ti2NbC2 (double MXene) nanohybrid-based non-enzymatic electrochemical biosensor for the detection of glucose in sweat.

The non-enzymatic electrochemical sensors are attractive due to their high sensitivity, quick detection, low cost, and simple construction. Hence, in this work, a non-enzymatic biosensor was constructed with NiCo2O4 nanoparticles (~ 82nm) decorated over Ti2NbC2 nanosheets by an in-situ method. The crystal structure, phase purity, morphology and elemental composition of the synthesized NiCo2O4/Ti2NbC2 nanohybrid was investigated using XRD, Raman and FESEM analysis. The electrocatalytic and electrochemical behaviour of the prepared nanohybrid was investigated using cyclic voltammetry and amperometry analysis. Hybrid of NiCo2O4/Ti2NbC2 produces a biocompatible, electrochemically active surface with enhanced electrical conductivity. The enhanced surface area of NiCo2O4 and superior electrical conductivity of Ti2NbC2 nanosheets helped to develop non-enzymatic electrochemical glucose sensor with enhanced sensitivity (425.6 µA mM-1cm-2), low limit of detection and quick response time that satisfy glucose detection applications. Thus, the developed non-enzymatic electrochemical glucose sensor has excellent electrochemical properties and making it as a strong candidate for the detection of glucose concentration in sweat.

Shear properties of composite steel plate connectors for prefabricated steel–concrete composite beams

As a critical component of prefabricated steel–concrete composite beams, ideal connectors can ensure the mechanical properties of bridges and significantly improve the efficiency of assembly construction. CSPC connector (Composite steel plate connector) with excellent load-slip curve and assembly construction efficiency was designed to realize fast and simple assembly construction. CSPC connectors require prefabricated bridge deck with no holes and low installation accuracy requirements. The results of 6 push-out specimens and 12 finite element models show that the CSPC connector exhibits an excellent load-slip curve compared to the existing connectors, and its shear stiffness and ductility coefficient are 1.03 and 1.51 times that of the stud connector, respectively. The shear stiffness and shear capacity of CSPC connectors are 0.79 times and 0.96 times the original when the grouting material age is reduced from 28 days to 3 days due to the rapid construction demand. The weakening of shear capacity is not obvious. The shear capacity of the CSPC connector comes from the connection between high-strength bolts and composite steel plates. The pressure-bearing effect of grouting material is crucial in connecting composite steel plates. Meanwhile, the composite steel plate of CSPC connector should be designed with equal thickness, a height of 30 mm and a spacing of no more than 10 mm. The recommended ratio of high-strength bolt diameter to composite steel plate thickness is 1.25. Finally, fit the load-slip relationship of CSPC connector, and propose a shear capacity formula with a deviation of less than 12 % from the test results.

A universal variational framework for parabolic equations and systems

We propose a variational approach to solve Cauchy problems for parabolic equations and systems independently of regularity theory for solutions. This produces a universal and conceptually simple construction of fundamental solution operators (also called propagators) for which we prove {text {L}}^2 off-diagonal estimates, which is new under our assumptions. In the special case of systems for which pointwise local bounds hold for weak solutions, this provides Gaussian upper bounds for the corresponding fundamental solution. In particular, we obtain a new proof of Aronson’s estimates for real equations. The scheme is general enough to allow systems with higher order elliptic parts on full space or second order elliptic parts on Sobolev spaces with boundary conditions. Another new feature is that the control on lower order coefficients is within critical mixed time-space Lebesgue spaces or even mixed Lorentz spaces.

ZIF-derived Fe,Co coordinated N/O-codoped three-dimensional tungsten–carbon matrix for the performance-enhanced zinc-air flow battery and water splitting

Constructing efficient and cost-effective electrocatalysts with oxygen reduction reaction (ORR), oxygen evolution reaction (OER), and hydrogen evolution reaction (HER) for the development of zinc-air flow batteries (ZAFBs) and overall water splitting (OWS) is significant, but still challenging. Herein, we have fabricated a heterojunction catalyst (Fe,CoZn9+9-NO/WC) featuring uniformly dispersed Fe and Co coordinated with riched-nitrogen/oxygen codoped into a three-dimensional highly porous tungsten–carbon matrix modified carbon nanotube by a simple stepwise construction route using water as the solvent. The resultant Fe,CoZn9+9-NO/WC exhibits a positive half-wave potential (E1/2) of 0.889 V for ORR, a low overpotential at 10 mA·cm−2 for OER (290 mV) and HER (84 mV), and excellent electrochemical durability in alkaline electrolyte, outperforming even benchmark catalysts. Moreover, Fe,CoZn9+9-NO/WC as a bifunctional air cathode for ZAFBs delivers higher open circuit voltage, peak power density (190 mW·cm−2), and specific capacity (814 mAh·g−1), lower charge/discharge voltage gap and prolonged operational cycles durability, largely exceeding those of the hybrid Pt/C+RuO2 bifunctional catalyst. The alkaline OWS electrolyzer is constructed by Fe,CoZn9+9-NO/WC with good stability and requires only 1.556 V cell voltage at 10 mA·cm−2. Impressively, the self-constructed Fe,CoZn9+9-NO/WC electrodes were applied to practical ZAFBs and OWS devices, demonstrating superior performance to the recently reported ZIF/MOF-derived catalysts in organic solvents. This work offers an economical synthetic strategy to prepare highly efficient multifunctional catalysts with practical potential for commercial production, promising to facilitate the development of clean energy storage and conversion devices.

Zinc selenide based dual-channel SPR optical biosensor for HIV genome DNA hybridization detection

Simultaneous measurement of human immunodeficiency virus (HIV) genome DNA hybridization and the DNA melting temperature in a prism-based surface plasmon resonance (SPR) biosensor is modeled theoretically using a simple dual-channel construction. The proposed sensor consists of a BK7 prism coated with silver as a plasmonic material. The metal surface is divided into two channels to detect medium refractive index (RI) and temperature. One half is covered with zinc selenide (ZnSe) semiconductor to enhance the hybridization detection sensitivity and to protect silver from oxidation. The other half is covered with polydimethylsiloxane (PDMS) polymer to detect the temperature variations. The proposed sensor is optimized numerically, and the optimum structure provides an excellent sensitivity of 208 deg/RIU, thanks to the use of the ZnSe layer, which is greater than double the reported dual-channel prism-based sensor in thickness. The polymer channel shows high sensitivity to the temperature variations of − 0.125 deg/°C, which is nearly 10 times the response of the RI channel to temperature variations. The data obtained from the polymer channel is used to compensate for the thermal perturbations of the sensing medium RI, and at the same time, to monitor the increments of the temperature in order to avoid reaching the DNA melting temperature. A mathematical expression is provided to consider the effect of the temperature variations on the RI of the sensing medium to get a better accurate detection process. The DNA hybridization detection of HIV is theoretically discussed in detail starting from the preparation of the sensing medium with the different ingredients until the hybridization between probe and complementary target DNA (ct-DNA) molecules.

Simple construction of multistage stable silicon-graphite nanosheets composites for lithium-ion batteries

Silicon/carbon composites are considered as the preferred anode materials for high energy density lithium-ion batteries due to their high capacity. However, the high cost of raw materials and the complex preparation process have resulted in expensive cost and poor batch stability of silicon-carbon materials, which have impeded their widespread adoption on a large scale. In this study, a multistage stable silicon-graphite nanosheets composite (Si-NSs/G-NSs@C) with intercalated and core-shell structure was produced from low-cost precursors of silicon nanosheets (Si-NSs) and graphite nanosheets (G-NSs) by simple modification-grafting-coating and heat treatment processes. Benefiting from the effective bonding, citric acid carbon coating, intercalation and core-shell structure, the Si-NSs/G-NSs@C composite exhibits excellent performance for lithium storage. The Si-NSs/G-NSs@C electrode, using the sodium alginate binder system, displays the reversible specific capacity of 821.4 mAh g−1 at 400 mA g−1, with the capacity retention rate of 80% after 200 cycles. When employing lithium polyacrylate as the binder, the composite electrode demonstrates the reversible specific capacities of 1048.9 mAh g−1 at 400 mA g−1 and 723.6 mAh g−1 at 1000 mA g−1. After 200 cycles, the capacity retention rates were 81% and 85%, respectively. In summary, the low-cost precursors, simple and controllable preparation process and excellent electrochemical performance will further promote the market application of silicon/carbon anode materials.

Mirror symmetry for five-parameter Hulek-Verrill manifolds

We study the mirrors of five-parameter Calabi-Yau threefolds first studied by Hulek and Verrill in the context of observed modular behaviour of the zeta functions for Calabi-Yau manifolds. Toric geometry allows for a simple explicit construction of these mirrors, which turn out to be familiar manifolds. These are elliptically fibred in multiple ways. By studying the singular fibres, we are able to identify the rational curves of low degree on the mirror manifolds. This verifies the mirror symmetry prediction obtained by studying the mirror map near large complex structure points. We undertake also an extensive study of the periods of the Hulek-Verrill manifolds and their monodromies. On the mirror, we compute the genus-zero and -one instanton numbers, which are labelled by 5 indices, as h^{1,1}\!=5h1,1=5. There is an obvious permutation symmetry on these indices, but in addition there is a surprising repetition of values. We trace this back to an S_{6}S6 symmetry made manifest by certain constructions of the complex structure moduli space of the Hulek-Verrill manifold. Among other consequences, we see in this way that the moduli space has six large complex structure limits. It is the freedom to expand the prepotential about any one of these points that leads to this symmetry in the instanton numbers. An intriguing fact is that the group that acts on the instanton numbers is larger than S_6S6 and is in fact an infinite hyperbolic Coxeter group, that we study. The group orbits have a “web” structure, and with certain qualifications the instanton numbers are only nonzero if they belong to what we term “positive webs”. This structure has consequences for instanton numbers at all genera.

A Load Control Strategy for Stable Operation of Free-Piston Electromechanical Hybrid Power System

Abstract The free-piston electromechanical hybrid power system (FEHS) affords the advantages of a simple construction and high thermal efficiency due to the removal of the crankshaft. However, the unrestricted trajectory of the piston linkage assembly (PLA) also gives rise to challenges for stable operation during the process of startup or operation. In order to realize the stable operation of free-piston electromechanical hybrid power system, this paper proposed a load control strategy. First, a dynamic model is established through thermodynamic and electromagnetic theory, and its effectiveness is verified by experiment and simulation. On this basis, a coupling load control model based on linear active disturbance rejection control (ADRC) is developed. The reliability of the proposed load control strategy is validated under different interference fluctuations. The simulation results demonstrate that no matter whether the interference occurs during the startup process or the operation process, the proposed control strategy exerts effective limiting function over the piston linkage assembly and maintain its stable operation. Moreover, compared with the proportion integral differential (PID) control strategy, the proposed strategy exhibits faster response times and a smoother startup process. The compression ratio fluctuation range was reduced from 0.1 to 0.001, and the control accuracy has been greatly improved.

Thermally assisted in situ synthesis of C3N5/TiO2 S-scheme heterojunctions with enhanced visible light response for photocatalytic hydrogen precipitation

Nitrogen-rich C3N5 has emerged as a promising visible light catalyst due to its narrow band gap. Nevertheless, its practical application is hindered by the rapid recombination of photogenerated carriers. To address this limitation and enhance the photocatalytic performance of C3N5-based photocatalysts, one effective measure involves the construction of heterojunctions in conjunction with other semiconductors. In this work, the C3N5/TiO2 S-scheme photocatalysts was constructed by matching C3N5 with a more negative conduction band (CB) and TiO2 with a more positive valence band (VB). Photoelectric tests exhibited that the prepared photocatalysts possessed enhanced visible light photoresponsivity as well as excellent charge separation and transport efficiencies. The characterization results of XPS and EPR confirmed that the existence of internal electric field and the unique S-scheme charge transfer mechanism, which achieves overall spatial separation of effective photogenerated carriers and accelerates the recombination of redundant electrons and holes. The photocatalytic hydrogen production performance of the TCN2 is 6.9 times and 30 times higher than that of C3N5 and TiO2, respectively, which is ascribed to the unique charge transfer mechanism of the S-scheme heterojunction and significantly enhanced photocatalytic activity. The simple construction of S-scheme heterojunctions in this work provides a new strategy for research in other fields.

Phase-Controlled Multibank Resistive Heating With Optimized Current Harmonics

This paper proposes an SCR phase controlled 3-phase 3-wire industrial heating system using multiple Delta Banks of resistors. In the proposed scheme, out of two similar groups denoted as ‘Set’, each has two resistance banks with a finite ratio of maximum power dissipation between them and operating with same controlled firing angle. Each bank of resistance is ‘Delta’ connected, one with SCRs in phase while the other with SCRs in line. This proposed configuration eliminates triplen besides some major characteristic harmonics in the line current. ‘Delta’ connection permits use of same voltage rating of all resistors. In the proposed scheme, two such Sets are operated with a fixed firing angle difference to substantially reduce residual harmonics without any additional filters. An offline-optimization process determines the operating conditions of the sets. The proposed scheme with simple construction & operation, wide power range, low THD makes it a practical and cost-effective solution. The modeling, analysis and performance of the proposed scheme are presented, with supporting simulation and experimental results.

Supervised Learning in a Multilayer, Nonlinear Chemical Neural Network.

The development of programmable or trainable molecular circuits is an important goal in the field of molecular programming. Multilayer, nonlinear, artificial neural networks are a powerful framework for implementing such functionality in a molecular system, as they are provably universal function approximators. Here, we present a design for multilayer chemical neural networks with a nonlinear hyperbolic tangent transfer function. We use a weight perturbation algorithm to train the neural network which uses a simple construction to directly approximate the loss derivatives required for training. We demonstrate the training of this system to learn all 16 two-input binary functions from a common starting point. This work thus introduces new capabilities in the field of adaptive and trainable chemical reaction network (CRN) design. It also opens the door to potential future experimental implementations, including DNA strand displacement reactions.

Hybrid constructed wetland for treatment of power plant effluent polluted with hydrocarbons

Constructed wetlands (CWs) have good potential for application in the treatment of various types of polluted water in Iraq, including industrial wastewater, due to their low cost relative to the current conventional treatment technologies. Hybrid CW with a continuous-flow system was tested for the treatment of highly polluted industrial wastewater from the Al-Najibiyia Power Plant in Basrah City for 72 days with 5 days of retention time. The system consisted of a horizontal subsurface flow system (HSSF) planted with Phragmites australis (Cav.) followed by a surface flow (SF) system planted with Hydrilla verticillata (L.f.) Royle. A second system without plants served as a contaminant control system. Total petroleum hydrocarbons (TPHs), petroleum aromatic hydrocarbons (PAHs) and water quality were measured for both raw and treated wastewaters and plant status parameters were monitored. The presence of both plants and substrate had a significant effect on the removal efficiency and mass removal rate of all pollutants at (p < 0.05). The planted system performance showed a percentage removal of pollutants reaching to: 65.9 % for BOD5, 91.0 % for COD and 88.8 % for total suspended solids (TSS) while removal efficiency of BOD5, COD and TSS for unplanted systems was only 44.7, 64.5 and 68.7 %, respectively. The removal efficiencies of TPHs, and PAHs by the hybrid system were 96.5, and 96.0 %, compared to only 71.0 % and 51.0 % for unplanted system, respectively, showing that hybrid CW could enhance pollutant removal efficiency better than single CW. It is revealed also that the high efficiency in removing pollutants is the result of the plant and substrate presence and the interaction between plants and the surrounding microbial community. Thus, constructed wetlands (CWs) are a good option for industrial wastewater treatment due to its simple construction and effectiveness to remove hydrocarbons.

The Importance of Being Prime⋆, a Nontrivial Generalization for Nonunique Factorizations

The notion of primeness is the key to the phenomenon of unique factorization. In particular, when unique factorization in a monoid fails, the arithmetic of that monoid is determined by the irreducible elements which are not prime. We illustrate this with examples of easy-to-understand monoids which are, for the most part, multiplicative submonoids of the natural numbers. Through these examples, we examine the ω-invariant, which offers a quantification of both primeness and nonunique factorization. We close by shifting gears and illustrating the same concepts in noncommutative semigroups, again by using relatively simple constructions involving positive integers.

Energy analysis of solar powered hydrogen production system with CuO/water nanofluids: An experimental investigation

Electrolysis is the process used to produce hydrogen using external electrical energy. Because of less initial and operating cost, less maintenance required, and simple construction, hydrogen production via water electrolysis has gained more attention among users globally. In this current attempt, a novel solar-powered hydrogen generation system was established and tested in different operating circumstances. Throughout the study, nanofluids with concentrations of 0.05%, 0.1%, and 0.2% were utilized, and their effect on electrical performance and hydrogen production rate was examined. Compared to conventional solar panels, the usage of nanofluids resulted in a significant improvement in electrical power productivity and hydrogen output rate. The highest electrical efficiency is with a 0.2% volume fraction of CuO/water nanofluids at 13.5% at Noon. During the same period, the lowest and highest hydrogen yield rates are found for the conventional PV module and 0.2% volume fraction CuO/water nanofluids-based system as 7.9 ml/min and 18.2 ml/min, respectively.

Proof of retrievability with flexible designated verification for cloud storage

With numerous applications in cloud storage, Proof of Retrievability (PoR) is an efficient solution for verification and retrieval of big data on a remote server. Existing PoR schemes can support two mutually exclusive verification modes, namely either private verifiability or public verifiability, depending on whether the outsourced data is verifiable by the data owner (user) only or by everyone. In order to allow the user to flexibly designate the capability of verification, we propose a novel framework for PoR schemes that enables fine-grained control of remote data verification for cloud storage. Our idea is enabling the user to dynamically release some tokens (verification keys) to one or more third parties (designated verifiers), such that only the user and the designated verifiers can verify and retrieve the outsourced data from the server. We formalize this notion as PoR with Flexible Designated Verification (PoR-FDV), and define an extended adversarial model for PoR-FDV based on Juel et al.'s PoR model. Under the new framework, we propose a generic, simple and elegant construction of PoR-FDV from public verifiable PoR and identity-based KEM/DEM, which then gives birth to a concrete and efficient PoR-FDV scheme. Compared to existing PoR schemes, PoR-FDV provides higher flexibility and scalability, as well as many useful features.

"Warm in Winter and Cool in Summer": Scalable Biochameleon Inspired Temperature-Adaptive Coating with Easy Preparation and Construction.

The highly reflective solar radiation of passive daytime radiative cooling (PDRC) increases heating energy consumption in the cold winter. Inspired by the temperature-adaptive skin color of chameleon, we efficiently combine temperature-adaptive solar absorption and PDRC technology to achieve "warm in winter and cool in summer". The temperature-adaptive radiative cooling coating (TARCC) with color variability is designed and fabricated, achieving 41% visible light regulation capability. Comprehensive seasonal outdoor tests confirm the reliability of the TARCC: in summer, the TARCC exhibits high solar reflectance (∼93%) and atmospheric transmission window emittance (∼94%), resulting in a 6.5 K subambient temperature. In the winter, the TARCC's dark color strongly absorbs solar radiation, resulting in a 4.3 K temperature rise. Compared with PDRC coatings, the TARCC can save up to 20% of annual energy in midlatitude regions and increase suitable human hours by 55%. With its low cost, easy preparation, and simple construction, the TARCC shows promise for achieving sustainable and comfortable indoor environments.

Exploiting Laser-Induced Graphene Composites as Substrates for Copper-Mediated Nitrate Reduction

The development of a nanostructured copper–laser-induced graphene (LIG) composite that can catalyze the reduction of nitrate is described. The system was characterized using a range of surface analytical methods (SEM, Raman, DekTak profilometry). The electrochemical performance of the copper mesh in reducing nitrate was investigated, the nature of the catalytic response was elucidated, and the influence of potential interferences was critically appraised. The adaptation of the system as the basis of an electrochemical sensor for nitrate was assessed, which displayed a limit of detection of 4.7 μM nitrate. The analytical applicability in authentic media was evaluated through the analysis of two surface water samples and validated by standard spectroscopic (nitrate reductase–Griess methods). The LIG substrate offers a simple, scalable route towards the reduction of nitrate with a construction simplicity and sensitivity that is competitive with much more complex nanomaterials.

From possessive to relative clause marker: a grammaticalization pathway in the Timor-Alor-Pantar languages

AbstractTypological studies have repeatedly expressed doubt about the possibility of relative clause markers grammaticalizing from possessive markers. At the same time, cross-linguistic studies of attribution have provided substantial evidence for markers of adjectival attribution deriving from possessive markers. Given that simple adjectival attributive constructions are accepted to expand readily into relative clause constructions, there is an apparent discordance in the typological literature on the diachronic sources of their markers. Using data from the Timor-Alor-Pantar languages of south-eastern Wallacea, the present article argues that the link between possessive and relative clause markers, by way of an adjectival attributive marker, should also be uncontroversial.

Analysis of influences of injection parameters on combustion process based on 2-stroke rod-less opposed piston diesel engine

Global concerns about environmental pollution and fuel consumption are increasing, and as emissions regulations become more stringent, exploring new power and structural forms to optimise diesel engines is the way forward for future breakthroughs in diesel engines. The 2-Stroke Rod-less Opposed Piston (2S-ROPE) has been extensively studied for its vibration-free and simple construction. Compared to conventional four-stroke engines, it has a smaller bore, shorter cycle time, higher power and lower fuel consumption in the same time, making it an ideal power source for small engines. In this paper, the rod-less structure is applied to a two-stroke opposed-piston diesel engine for the first time. Based on experimental verification by spraying, a dynamic high-precision three-dimensional model of computational fluid dynamics (CFD) is established, using lateral injection, to clarify the various airflow patterns that occur in the cylinder during the intake and exhaust of the 2S-ROPE, and investigates the effects of injection timing and injection pressure on the oil–gas mixing and combustion processes in the 2S-ROPE cylinder. The results show that the in-cylinder turbulent kinetic energy is highest at an injection timing of 15° BTDC (Before Top Dead Center) and that fuel injection has the greatest effect on in-cylinder airflow disturbance at this time. At 17.5° BTDC, the duration of in-cylinder combustion was the longest. The effect of injection timing on the burst pressure is linear, for every 2.5° advance, the maximum pressure in the cylinder increases by about 2 MPa. 20 MPa of injection pressure increases, the stall period is shortened by less than 1°, the combustion duration CA10-90 is shortened with the increase in injection pressure, and for every 20 MPa increase in injection pressure, the burst pressure increases by 1 MPa, which is a significant increase.