Large Tolerance Research Articles

High-performance gas sensing in metagrating-based vertical cavity with larger fabrication tolerances driven by quasi-bound states in the continuum

We proposed a novel vertical cavity structure for gas sensing, utilizing double-layer metagratings and a distributed Bragg reflector (DBR). By adjusting the position of the upper-layer grating, we were able to achieve symmetry-protected bound states in the continuum (SP-BIC) and Fabry-Pérot BIC (FP-BIC). The resonance peaks of these quasi-BICs can be tuned by modifying structural parameters like grating thickness, width, and cavity length. Notably, our structure exhibited high sensing performance while allowing for significant fabrication tolerances. Simulation results indicate that the sensitivities of the gas sensor can reach 927 nm/RIU and 1026 nm/RIU, corresponding to figure of merit (FOM) of 15450 RIU−1 and 24604 RIU−1. The proposed structure with large fabrication tolerances has potential applications in gas sensing.

PLC-Based Polymer/Silica Hybrid Inverted Ridge LP11 Mode Rotator.

The mode rotator is an important component in a PLC-based mode-division multiplexing (MDM) system, which is used to implement high-order modes with vertical intensity peaks, such as LP11b mode conversions from LP11a in PLC chips. In this paper, an LP11 mode rotator based on a polymer/silica hybrid inverted ridge waveguide is demonstrated. The proposed mode rotator is composed of an asymmetrical waveguide with a trench. According to the simulation results, the broadband conversion efficiency between the LP11a and LP11b modes is greater than 98.5%, covering the C-band after optimization. The highest mode conversion efficiency (MCE) is 99.2% at 1550 nm. The large fabrication tolerance of the proposed rotator enables its wide application in on-chip MDM systems.

2'-Fucosyllactose Inhibits Human Norovirus Replication in Human Intestinal Enteroids.

Human noroviruses (HuNoVs) are the leading cause of acute gastroenteritis worldwide. Currently, there are no targeted antivirals for the treatment of HuNoV infection. Histo-blood group antigens (HBGAs) on the intestinal epithelium are cellular attachment factors for HuNoVs; molecules that block the binding of HuNoVs to HBGAs thus have the potential to be developed as antivirals. Human milk oligosaccharides (HMOs) are glycans in human milk with structures analogous to HBGAs. HMOs have been shown to act as decoy receptors to prevent the attachment of multiple enteric pathogens to host cells. Previous X-ray crystallography studies have demonstrated the binding of HMO 2'-fucosyllactose (2'FL) in the same pocket as HBGAs for some HuNoV strains. We evaluated the effect of 2'FL on the replication of a globally dominant GII.4 Sydney [P16] HuNoV strain using human intestinal enteroids (HIEs) from adults and children. A significant reduction in GII.4 Sydney [P16] replication was seen in duodenal and jejunal HIEs from multiple adult donors, all segments of the small intestine from an adult organ donor and in two pediatric duodenal HIEs. However, 2'FL did not inhibit HuNoV replication in two infant jejunal HIEs that had significantly lower expression of α1-2-fucosylated glycans. 2'FL can be synthesized in large scale, and safety and tolerance have been assessed previously. Our data suggest that 2'FL has the potential to be developed as a therapeutic for HuNoV gastroenteritis.

Lessons Learned from Failures and Design Improvements for Large Diameter Seals

Large diameter seals are used in Prototype Fast Breeder Reactor (PFBR) to prevent the escape of radioactive argon cover gas through wide annular gaps. The design of these seals shall address different challenges than normal seals. The large tolerances needed on the width of annulus, achievable tolerances on rubber, clearances in the seal holder, etc., influence the seal performance. The paper discusses analytical and experimental work done to develop robust large diameter seals. The contours of the present study are based on the feedback from the testing and qualification of small size model seals. Various permutations of geometry for seal and its holder are numerically investigated. The study mainly highlighted the influence of seal holder on the seal performance. Various sensitivity studies done on selected seal and seal holder demonstrated robustness of the design solutions.Graphical

Design and analysis of a large tolerance docking mechanism

On-Orbit Servicing is increasingly crucial with the growing number of spacecraft. The foundation for On-orbit servicing is space docking mechanisms. As On-Orbit Servicing tasks become more complex, the demands for docking capture mechanisms increase in both function and performance. Therefore, it is crucial to design a docking mechanism with a large tolerance. Among various docking capture mechanisms, the multi-claw capture mechanism has the advantages of low impact and reliable capture. This paper analyzes the Common Berthing Mechanism and a docking mechanism with an underactuated two-degree-of-freedom claw-type capture mechanism as its core is proposed. Subsequently, this paper provided a detailed design of the mechanism based on the principle of underactuated capture. Furthermore, this article conducts numerical analyses of key mechanisms such as the capture mechanism and guide mechanism in the design process, verifying the functionality of the mechanisms. After completing the analysis of capturing dynamics, the tolerance ability of the mechanism was also verified, various key parameters were determined, and the parameters of components such as the torsion spring were also determined. Finally, the prototype of the proposed docking mechanism is developed, and the experiment is completed to validate its functional principle and tolerance capability.

Ultra-broadband metamaterial absorber for collecting electromagnetic waves from the ultraviolet to the mid-infrared

Due to the inherent local limitations of surface plasmon resonance, it is challenging to design an ultra-broadband electromagnetic wave absorber covering multiple bands. In this paper, a novel Ultra-broadband perfect absorber is designed, which is a simple-type structure composed of metal-dielectric-metal (MDM), and the resonant cavity formed by metal and dielectric realizes high absorption. The calculated results of the absorber show that the average absorption rate in the range of 200–8000 nm is 95.70%, and the absorption bandwidth over 90% is 7800 nm. The ultra-broadband absorption can be attributed to the coupling effect of multiple resonances inside and outside the resonant cavity, which gives our proposed structure a wider bandwidth and higher light absorption capacity than the previously reported work and further reduces the complexity of the structure. When it is replaced by other materials, the structure also maintains high absorbency. In addition, the structure is not only polarization insensitive but also has wide-angle absorption, and it maintains high absorption in transverse magnetic (TM) mode and transverse electric (TE) mode. Even when the incident angle increases to 58°, the average absorption rate is still above 80%. It also has the characteristics of large process tolerance and strong adaptability to changing environments. These results allow the absorber to be applied in solar energy collection, infrared imaging and thermal detection, and optoelectronic devices.

Facile one-pot green synthesis of Aloe vera mediated silver nanoparticles and their catalytic efficiency towards organic transformations

A facile approach for the synthesis of Aloe vera mediated silver nano-particles (AgNPs) has been carried out via chemical route. The developed Aloe vera mediated AgNPs were characterized by using various techniques such as SEM, FT-IR etc. Additionally, catalytic applications of this interesting nanomaterial were utilized for the synthesis of 4-phenylthiazole- 2-amine and its derivatives. After completion of catalytic reactions, Aloe vera mediated AgNPs were easily recycled without any significant loss in catalytic activity. The robust features of the current approach involve an outstanding catalytic performance, ease of catalyst retrievability, easy work up procedure, and large substrate tolerance. Besides this, the green chemistry metrics for the products formed such as E-factor (Environment Factor), PMI (Process Mass Intensity), RME (Reaction Mass Efficiency), Atom Economy (AE) and carbon efficiency (CE) were in associated with high efficiency and selectivity which further confirms the effectiveness of this approach. This work highlights the significance of using economic and eco-friendly approach for synthesizing thiazole derivatives in good to excellent yields via Aloe vera mediated AgNPs under waste free conditions.

Polarization-insensitive and high-efficiency edge coupler for thin-film lithium niobate.

In this Letter, we propose and demonstrate a fiber-to-chip edge coupler (EC) on an x-cut thin film lithium niobate (TFLN) for polarization-insensitive (PI) coupling. The EC consists of three width-tapered full-etched waveguides with silica cladding and matches well with a single-mode fiber (SMF). The measured results show that the minimum coupling losses for TE0/TM0 modes remain to be 0.9 dB/1.1 dB per facet, and the polarization dependent loss (PDL) is <0.5 dB over the wavelength range from 1260 to 1340 nm. Moreover, the EC features large misalignment tolerance of ±2 µm in the Z direction and ±1.5 µm in the X direction for both polarizations for a 1 dB penalty. To the best of our knowledge, this is the first realized O-band edge coupler on TFLN with SMF. The proposed device shows promising potential for integration into TFLN polarization diversity devices.

Highly efficient fiber to Si waveguide free-form coupler for foundry-scale silicon photonics

As silicon photonics transitions from research to commercial deployment, packaging solutions that efficiently couple light into highly compact and functional sub-micrometer silicon waveguides are imperative but remain challenging. The 220 nm silicon-on-insulator (SOI) platform, poised to enable large-scale integration, is the most widely adopted by foundries, resulting in established fabrication processes and extensive photonic component libraries. The development of a highly efficient, scalable, and broadband coupling scheme for this platform is therefore of paramount importance. Leveraging two-photon polymerization (TPP) and a deterministic free-form micro-optics design methodology based on the Fermat’s principle, this work demonstrates an ultra-efficient and broadband 3-D coupler interface between standard SMF-28 single-mode fibers and silicon waveguides on the 220 nm SOI platform. The coupler achieves a low coupling loss of 0.8 dB for the fundamental TE mode, along with 1 dB bandwidth exceeding 180 nm. The broadband operation enables diverse bandwidth-driven applications ranging from communications to spectroscopy. Furthermore, the 3-D free-form coupler also enables large tolerance to fiber misalignments and manufacturing variability, thereby relaxing packaging requirements toward cost reduction capitalizing on standard electronic packaging process flows.

All-Silicon Polarization-Insensitive Metamaterial Absorber in the Terahertz Range.

All-silicon terahertz absorbers have attracted considerable interest. We present a design and numerical study of an all-silicon polarization-insensitive terahertz metamaterial absorber. The meta-atoms of the metamaterial absorber are square silicon rings which can be viewed as gratings. By properly optimizing the structure of the meta-atom, we achieve a broadband absorptivity that is above 90% ranging from 0.77 THz to 2.53 THz, with a relative bandwidth of 106.7%. Impedance matching reduces the reflection of the terahertz waves and the (0, ±1)-order diffraction induce the strong absorption. The absorption of this absorber is insensitive to the polarization of the terahertz wave and has a large incident angle tolerance of up to 60 degrees. The all-silicon metamaterial absorber proposed here provides an effective way to obtain broadband absorption in the terahertz regime. Metamaterial absorbers have outstanding applications in terahertz communication and imaging.

Solar energy broadband capturing by metamaterial absorber based on titanium metal.

In recent years, the exploration of solar absorbers has grown in favor due to the scarcity of energy. Here, we propose an absorber with an array of a circular ring surrounding disk (RSD) for solar energy capture. The novel structure keeps above 93.5% absorption with an average absorption of 96.95% in wavelengths from 300 to 4000nm. Meanwhile, the proposed absorber is advantageous in that the structure is generalizable to other metals and dielectric materials. Furthermore, the data results show that the absorber has polarization-independent properties as well as maintaining >90% absorption in the considered wavelength range up to an incidence angle of 52° and >95% absorption at large process tolerances. Finally, the excellent absorption under the AM1.5 solar spectrum demonstrates the RSDabsorber's ability to capture solar energy. These results show the potential of the absorber for applications in electromagnetic invisibility cloaking, thermal emitters, and solar energy capture and conversion.

Tunable wide-angle dual-channel nonreciprocal radiation in a hybrid graphene–Weyl semimetal structure

Nonreciprocal radiation, violating Kirchhoff’s law, has sparked significant interest due to its potential in energy conversion and capture technologies. In this paper, we introduce a hybrid structure combining graphene and Weyl semimetal to achieve tunable dual-channel nonreciprocal radiation through guided mode resonances. This structure overcomes the limitations of traditional single-channel systems by offering dual-channel nonreciprocal radiation, enhanced efficiency, and increased flexibility. The structure exhibits excellent wide-angle nonreciprocal characteristics. Furthermore, by investigating the impact of structural parameters, the structure demonstrates large parameter tolerance, facilitating practical fabrication. Finally, leveraging the tunable properties of graphene, we showcase the linear control behavior of the system. Our findings pave the way for advanced energy-harvesting and conversion structures in advanced thermal systems.

Interfacial swelling engineered superhydrophobic and electrically conductive coatings for multifunctional piezoresistive sensors

Conductive foam composites (CFCs) based pressure sensors show promising applications in flexible electronics, but it is still difficult to develop cost-effective methods for preparation of multifunctional CFC pressure sensors with a large working strain and environment tolerance. Herein, a facile “carbon nanotubes (CNTs) decoration and simultaneous hydrophobization” method is proposed to fabricate electrically conductive and superhydrophobic foam composites. CNTs/stearic acid (SA) are anchored onto the skeleton of the partially swelled styrene-butadiene rubber (SBR) foam via one step ultrasound-assisted interface sintering. The obtained superhydrophobic SA/CNTs decorated foam composites (SCFCs) with strong interfacial adhesion exhibit outstanding corrosion resistance and durability. SCSF piezoresistive sensors show a wide compressive strain sensing range (10–95 %) and a great durability over 11,000 cycles and can work normally in underwater or even corrosive conditions. In addition, SCFCs possess excellent photothermal conversion performance and their resistance exhibits negative temperature coefficiency, making them promising as temperature sensors.

Bond-slip behavior of deformed rebar in grouted duct connection: Experiment, theoretical analysis and cohesive-zone element model

In precast bridge piers, the grouted corrugated duct (GCD) connection can offer advantages of accommodating large construction tolerances and being cost-effective. However, this connection is relatively new, and its bond strength and effective bond length are a concern in structural design. To fill the research gap of the bond behaviors of the GCD connection, experimental tests of 36 pull-out specimens with/without GCD were conducted in this paper. The influencing factors of bond strength were investigated, including duct, rebar diameter and anchorage length. The results revealed that the GCD connection required a shorter anchorage length and exhibited a plumper bond-slip curve and higher bond strength compared to the specimen without GCD connection. Then, an analytical model based on thick-walled cylinder theory was proposed to construct the bond-slip curve of GCD connection, and to identify the criteria for mortar strength. To simulate the bond-slip relationship in finite element model, a cohesive-zone element model realized by the zero-thickness user defined element was developed at the interface between rebar and dummy rebar. Finally, a comparison was made among the solution of proposed bond-slip model, finite element analysis, and the tested data, demonstrating good consistency between the three.

Design, optimization and verification of a conical guiding origami mechanism for underwater docking station

Underwater docking station requires a conical guiding device with a large tolerance capacity and smaller volume to recover unmanned underwater vehicles (UUVs). Here, this paper innovatively introduces a conical guiding origami mechanism designed by an array and rotation approach based on a rigid origami mechanism. The Jacobian matrix method systematically calculates the degree of freedom (DOF) of the device. The variation function of dihedral angle in the folding process of the origami mechanism is derived, and the kinematics model is established within the Cartesian coordinate system. Based on this model, we established a mathematical model for optimizing the origami mechanism by considering number of units and unit volume as the design variables, subject to minimizing the underwater flow area and length. The sequential quadratic programming algorithm is employed to identify the optimum design variables. Subsequently, based on optimized results, collision simulation is carried out, and a conical guiding device tailored for an underwater docking station is successfully designed. The proposed device can be used as an underwater docking station to recover UUVs for ocean exploration. The proposed device has a large tolerance capacity, minimal shrinkage state cross-sectional area and length, excellent hydrodynamic performance, and a high spatial utilization rate.

Macrocyclic Sulfur Ligand Stabilized Trans-Palladium Dichloride Complex: Syntheses, Structure, Chlorine Rotation, and Application in α-Olefination of Nitriles by Primary Alcohols.

Herein, we have reported the synthesis of a macrocyclic organosulfur ligand (L1) having a seventeen-membered macrocyclic ring. Subsequently, the corresponding trans-palladium complex (C1) of bulky macrocyclic organosulfur ligand (L1) was synthesized by reacting it with PdCl2 (CH3 CN)2 salt. The newly synthesized ligand and complex were characterized using various analytical and spectroscopic techniques. The complex showed a square planar geometry with trans orientation of two ligands around the palladium center. The complex possesses intramolecular SCH…Cl interactions of 2.648 Å between the macrocyclic ligand and palladium dichloride. The potential energy surface (PES) for the rotational process of C1 suggested a barrier of ~23.81 kcal/mol for chlorine rotation. Furthermore, the bulky macrocyclic organosulfur ligand stabilized palladium complex (C1) was used as a catalyst (2.5 mol %) for α-olefination of nitriles by primary alcohols. The α,β-unsaturated nitrile compounds were found to be the major product of the reaction (57-78 % yield) with broad substrate scope and large functional group tolerance. Notably, the saturated nitrile product was not observed during the reaction. The mechanistic studies suggested the formation of H2 and H2 O as only by-products of the reaction, thereby making the protocol greener and sustainable.

Reactivity-matched synthesis of monodisperse Ag(In,Ga)S2 QDs with efficient luminescence.

I-III-VI quantum dots (QDs) have gained widespread attention owing to their significant advantages of non-toxicity, large structural tolerance, and efficient photoluminescence potential. However, the disbalance of reactivity between the elements will result in undesired products and compromised optical properties. Reducing the activity of highly reactive group IB elements is the most common approach, but it will reduce the overall reactivity and lead to a wide dispersion of QD sizes. In this study, we propose a method to improve the overall reactivity of the reaction system using the highly active IIIA precursor InI3, which triggers rapid nucleation and promotes the formation of Ag(In,Ga)S2 (AIGS) QDs, resulting in monodisperse particle size distributions and a significantly improved photoluminescence quantum yield (PLQY) (from 12% to 72%). Furthermore, narrow band edge emission is realized by coating a gallium sulfide (GaSx) shell on the basis of obtaining high-quality AIGS QDs. The core/shell QDs exhibit a 90% PLQY with a full width at half maximum (FWHM) of only 31 nm at 530 nm. This study provides a viable design strategy to synthesize monodisperse AIGS QDs with a narrow peak width and efficient luminescence, promoting the application of AIGS QDs in the field of luminescent displays.

Osmoregulatory Plasticity in Oreochromis niloticus-Nile Tilapia, and it’s Possible Estuary Use for Rivers Dispersion

Nile tilapia is a widely farmed species globally, due to its resistance to environmental challenges. Additionally, it is a generalist consumer and a prolific breeder. In Brazil, this fish is recognized as an invasive species because of its high dispersion and establishment rates, which compromise native biota. Estuarine waters (0.06 - 32‰) are being used in tilapia aquaculture, which is a promisor fish farming for euryahalinity species. The tilapia’s euryhalinity is well-know, but most protocols are based on gradual exposure. This research showed the tolerance of Nile tilapia on abrupt exposure to 0‰ (FW), and 10, 20, 30, 35 or 40‰, over in 6, 12 and 24 hours. An abrupt exposure resistance demonstrate that this fish can use estuaries to disperse for other watersheds. After experimental design the blood sample was taken after anesthesia was administered. Subsequently, fish was euthanized by spinal section, for muscle and gills samples collections. All samples were keep freezing until ionic, dehydration and enzyme measurement. Nile tilapia survived 24h until 30‰, 12h at 35‰ and 9h at 40‰. Osmolality increase and muscle dehydration decrease both above 20‰. While sodium levels keep regulated in all salinities, chloride, potassium and magnesium levels also increased above 20‰. These results prove that tilapia can easily tolerate abrupt exposure until 20‰ without an osmotic stressor. Gill carbonic anhydrase (C.A.) activity decreased at 30‰, and NKA did not change along salinities and times. These results complements plasma and dehydration averages, showing the large tolerance of this specie to salinity challenges, even in abrupt exposure. Then, these results can be used for discuss about the estuary fish farming system for tilapia, as this species may use estuarine waters to nearby rivers and also can harm the native ecosystem.

Flexible Kokotsakis Meshes with Skew Faces: Generalization of the Orthodiagonal Involutive Type

In this paper, we introduce and study a remarkable class of mechanisms formed by a 3 × 3 arrangement of rigid quadrilateral faces with revolute joints at the common edges. In contrast to the well-studied Kokotsakis meshes with a quadrangular base, we do not assume the planarity of the quadrilateral faces. Our mechanisms are a generalization of Izmestiev’s orthodiagonal involutive type of Kokotsakis meshes formed by planar quadrilateral faces. The importance of this Izmestiev class is undisputed as it represents the first known flexible discrete surface – T-nets – which has been constructed by Graf and Sauer. Our algebraic approach yields a complete characterization of all flexible 3 × 3 quad meshes of the orthodiagonal involutive type up to some degenerated cases. It is shown that one has a maximum of 8 degrees of freedom to construct such mechanisms. This is illustrated by several examples, including cases which could not be realized using planar faces. We demonstrate the practical realization of the proposed mechanisms by building a physical prototype using stainless steel. In contrast to plastic prototype fabrication, we avoid large tolerances and inherent flexibility.

Flexible broadband metamaterial absorber in long-wave infrared with visible transparency fabricated by laser direct writing.

Absorption of the long-wave infrared from human beings and the surroundings is a key step to infrared imaging and sensing. Here we demonstrate a flexible and transparent broadband infrared absorber using the photoresist-assisted metamaterials fabricated by one-step laser direct writing. The photoresist is patterned by the laser as an insulator layer as well as a mask to build the complementary bilayer metamaterials without lithography. The average absorptivity is 94.5% from 8 to 14 μm in experiment due to the broadband destructive interference of the reflected beam explained by the Fabry-Perot cavity model. The proposed absorber is applicable to various substrates with additional merits of polarization insensitivity and large angle tolerance, which offers a promising solution for thermal detection and management.