Extra Structure Research Articles

Dual Function Polymer Ligands of Perovskite Nanocrystals for Extraordinary Water Resistance and X‐Ray Imaging Scintillators

AbstractLead perovskite nanocrystals (PNCs) have shown great potential for optoelectronic device applications due to their excellent optoelectronic properties. However, the application of PNCs is significantly limited due to the inferior stability resulting from the highly dynamic ligands on the surface. Herein, poly(maleic anhydride‐alt‐1‐octadecene) (PMAO) with low molecular weight (Mn = 1911) is synthesized by copolymerization and used as multi‐dentate ligands to prepare CsPbBr3 PNCs via hot injection. The PNCs exhibit excellent water resistance, which maintains fluorescence for 2600 min while conventional PNCs are completely destroyed after 100 min. Density functional theory calculations demonstrate that PMAO as a multi‐dentate ligand has higher adsorption energy to the surface of PNCs. Due to the large amount of extra anhydride structure of PMAO, PMAO‐PNCs are used as a cross‐linking agent to directly prepare flexible films by an in situ one‐step polymerization reaction with 1,3‐bis(3‐aminopropyl) polydimethylsiloxane (PDMS‐NH2). The fluorescent flexible films show great potential for applications including X‐ray imaging scintillators and flexible light‐emitting diodes (LEDs). This study can provide guidance to prepare ultra‐stable PNCs and flexible perovskite films with good stability in a simple and efficient way.

A Self-Decoupling Method for MIMO Linear and Planar Dielectric Resonator Antenna Arrays Based on Transmission Characteristics of Feeding Structure

In this paper, a novel self-decoupling method for the multi-input multi-output (MIMO) dielectric resonator antenna (DRA) arrays is investigated. This method is based on the transmission characteristics of the conformal strip that feeds the DRA. It is found that when the strip-fed DRA operates in the higher-order mode, e.g., TE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">113</sub> mode, the E-field coupled to the metal strip of the adjacent passive DRA presents a standing wave distribution. By appropriately adjusting the dimensions of the feeding strip, the E-field can form a node with zero amplitude at its bottom where a coaxial probe is connected, preventing the energy from getting into the receiving port and hence achieving a high isolation level without requiring any extra decoupling structure. This self-decoupling method is applicable not only to one-dimensional (1-D) H- and E-plane coupled MIMO linear arrays but also to two-dimensional (2-D) MIMO planar array. To verify its feasibility, a prototype of 2 × 2 MIMO planar DRA array is simulated, processed, and tested. The results show that a usable bandwidth (|S <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ii</sub> | < -10 dB and |S <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">ij</sub> | < -20 dB) of 10.8% is achieved, and the maximum isolation is over 40 dB within the passband.

Measurement disturbance and conservation laws in quantum mechanics

Measurement error and disturbance, in the presence of conservation laws, are analysed in general operational terms. We provide novel quantitative bounds demonstrating necessary conditions under which accurate or non-disturbing measurements can be achieved, highlighting an interesting interplay between incompatibility, unsharpness, and coherence. From here we obtain a substantial generalisation of the Wigner-Araki-Yanase (WAY) theorem. Our findings are further refined through the analysis of the fixed-point set of the measurement channel, some extra structure of which is characterised here for the first time.

A Compact Low-Profile Differential Dual-Polarized Filtenna Without an External Filter Circuit for Vehicular Communications

A compact low-profile differential dual-polarized filtenna without an external filter circuit for vehicular communications is proposed in this paper. It has a compact, low-profile, simple, and symmetrical structure, which consists of four identical quarter circular patches with a pair of crossed feeding lines symmetrically and orthogonally embedded. Good filtering performance with three radiation nulls (RNs) generated without extra filtering structure is achieved, and the production mechanisms of three RNs are studied numerically. To get a deep insight into its working mechanism, the proposed structure is analyzed, and the equivalent lumped circuit is modeled and simulated. The prototype antenna with low profile of 2.832 mm and average gain of about 9.1 dBi within the frequency band of 5.28-6.11 GHz is fabricated and measured. Moreover, the measured polarization isolation is more than 44 dB within the operating band and the measured cross-polarization level is less than -29 dB. Good agreement between simulated and measured results can be acquired. The proposed antenna is a good candidate for in-vehicle local area networks (WLAN), in-vehicle Wi-Fi 6E, vehicle-to-vehicle (V2V) communication and 5G vehicle-to-basestation communication applications.

A Monolithically Printed Filtering Waveguide Aperture Antenna

This letter presents the design of a 3 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">rd</sup> order filtering waveguide aperture antenna based on coupled cavity resonators. Three offset-coupled rectangular waveguide cavities are employed in the design realizing two nested loaded-stubs without costing extra structure and size. The loaded-stubs introduce two controllable transmission zeroes and enhance the out-of-band realized gain selectivity. To validate the predicted results, a prototype operating at the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">X-</i> band frequencies has been fabricated monolithically using the 3-D selective laser melting printing technique. The measured results are in very good agreement with the simulated results, showing a flat gain response of 7.0 ± 0.2 dBi from 9.5–10.5 GHz with very good out-of-band selectivity. The fractional bandwidth is about 10% at 10 GHz when <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">S</i> <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11</sub> = -20 dB. Compared to the previously designed filtering antennas, the proposed design has the advantages of stronger out-of-band gain selectivity and low profile.

4D flat-space scattering amplitude/CFT3 correlator correspondence revisited

In this paper, we make connection between CFT3 three point correlation function of conserved currents and 4D three point amplitude of general spin massless gauge field explicit. We do so by taking flat space limit of momentum space CFT correlation function and show how they reproduce flat space amplitudes. We then point out a mismatch between number of independent structures in 3D CFT correlator of conserved currents and 4D flat space covariant vertex of massless higher spin fields. This is in contrast with general expectation that counting of 3d CFT correlator and 4d flat space amplitude should match. This mismatch is even more pronounced in spinor helicity variables.We also point out an interesting relation between parity even and parity odd flat space amplitude in momentum space. This observation helps us to construct a new momentum space CFT structure which accounts for the mismatch. However we should mention that this extra CFT structure can't be constructed out of conserved currents and hence counting mismatch between CFT correlation of conserved currents and flat space amplitude of massless gauge field persists. Story in spinor helicity variable is more complicated and is discussed in detail. We further comment on the connection of CFT correlation function in spinor helicity variables to AdS amplitudes in spinor helicity variables and light cone variables.

A filtering waveguide aperture antenna based on all‐resonator structures

AbstractIn recent years, there has been a large amount of attention focused on the design of filtering antennas to reduce the front‐end size of modern wireless communication systems. Although numerous design approaches are presented in the literature, they are usually applicable to a certain microwave circuit structure. Additionally, their implementations demand extra matching circuits or a structure which leads to an increase in the filtering antenna size. In this paper, the design of a 3rd‐order filtering antenna operating at the X‐band frequencies is presented utilizing the coupling matrix approach. It is based on 3rd order coupled‐resonators filter without employing any extra structure. For the physical configuration, three inline coupled rectangular waveguide cavity resonators operating at TE101 mode are employed. The output of the last resonator is coupled to free space via a rectangular aperture. The dimensions of the aperture are manipulated to control the radiation quality factor (Qr). To validate the simulated results, the design has been fabricated using the Computer Numerical Control technique. Excellent agreement between the simulation and measurement results has been obtained. The fractional bandwidth (FBW) is more than 10% when the reflection coefficient S11 = −20 dB. The gain response is very flat (7.54 0.2 dBi) from 9.5 to 10.5 GHz. The proposed filtering antenna is compact and low profile which may be of interest in radar applications.

A categorical derivation of Lebesgue integration

AbstractWe identify simple universal properties that uniquely characterize the Lebesgue spaces. There are two main theorems. The first states that the Banach space , equipped with a small amount of extra structure, is initial as such. The second states that the functor on finite measure spaces, again with some extra structure, is also initial as such. In both cases, the universal characterization of the integrable functions produces a unique characterization of integration. We use the universal properties to derive some of the basic elements of integration theory. We also state universal properties characterizing the sequence spaces and , as well as the functor taking values in Hilbert spaces.

Optimization of the Hydrodynamic Performance of a Wave Energy Converter in an Integrated Cylindrical Wave Energy Converter-Type Breakwater System

AbstractWave energy converters (WECs) are built to extract wave energy. However, this kind of device is still expensive for commercial utilization. To cut down the cost of WECs by sharing the construction cost with breakwaters, an integrated cylindrical WEC-type breakwater system that includes a cylindrical WEC array in front of a very long breakwater is proposed to extract wave energy and attenuate incident waves. This paper aims to optimize the performance of the integrated cylindrical WEC-type breakwater system. A computational fluid dynamics tool, openfoam®, and a potential flow theory-based solver, HAMS®, are utilized. openfoam® provides viscosity corrections to a modified version of HAMS® in order to accurately and efficiently predict the integrated system’s performance. Parametric studies are conducted to optimize the integrated system, and a novel setup with an extra arc structure is found to significantly improve the performance of the integrated system.

A Self-Decoupling Method for MIMO Antenna Array Using Characteristic Mode of Ground Plane

A self-decoupling method for the multiinput multioutput (MIMO) antenna array is investigated. This method is based on the specific characteristic mode (CM) of the ground plane, which features two or multiple parallel null-field regions. By using one antenna element to excite such a mode on the ground plane while placing the other one/ones in a way that their feed points are located in the null-field region, very high isolation between antenna elements can be obtained naturally. To validate the feasibility of this decoupling method, a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$1\times $ </tex-math></inline-formula> 2 microstrip patch antenna (MPA) array is simulated, fabricated, and measured. It has been shown that a maximum isolation level of 57 dB is achieved without any extra decoupling structure. Moreover, this self-decoupling method shows strong universality and extensibility, and it applies to different types of antenna arrays and multielement arrays.

A study of yolk sac diameter in predicting abnormal outcome of pregnancy in rural hospital

Introduction: Early pregnancy loss is the most common complication of early pregnancy. First trimester is crucial, since 80% of pregnancy losses occur spontaneously during this period. There is great difficulty in reliably anticipating which pregnancies will terminate in abortion. The yolk sac is the first extra embryonic structure that becomes sonographically visible within the gestational sac. Aims and Objectives of the present study is to evaluate the size of yolk sac as a predictor of pregnancy outcome.Material and Methods: The present Observational Prospective study was conducted on 104 pregnant woman with gestational age 6 to 10 weeks attending OPD in the department of obstetrics and gynaecology at MVJ Medical college and research hospital from December 2020 to December 2022 Results: In present study Mean age of the study participants was 25.31+4.483 and mean values of radiological findings were gestational age (days)56.28days ±8.120, MSD was 2.2545±0.99, YSD was 2.25±0.99, CRL was 1.29±0.66 and HR was 156.61±13.453. Majority of the study participants 71.2% had normal perinatal outcome. There is steady increase in YSD mean value and difference observed is statistically significant. Statistically significant differences were observed between normal and abnormal perinatal outcome.Conclusion: Abnormalities of YS size or shape, early regression or absence can be used as poor predictor of first trimester pregnancy outcome, even before studying the fetal morphology.

An In-Vitro Analysis of Root Fracture Strength Using Single File Systems.

Aim Root canal obturation during endodontic therapy supports the root canal space and helps the extra tooth structure resist fracture.Some believe endodontic-treated teeth are more likely to break than natural teeth. The most common causes of tooth decay are endodontic treatment's extensive tooth structure loss and coronal and radicular dentin drying. Materials and methods Two hundred removed human permanent mandibular first molars were allowed to be stored in isotonic saline solution for a maximum of 72 hours. The collection, storing, sterilizing, and handling of the samples were done per the Occupational Safety and Health Administration (OSHA) and Centers for Disease Control and Prevention(CDC)guidelines. Out of a total of 200 newly removed mandibular first molars, 120 teethwere finally gathered, sterilized, and kept in 1% thymol in normal saline at 30 degrees Celsius. The access cavity was prepared, and the pulp chamber was cleaned and debridedusing an ultrasonic scaler tip while being irrigated with regular saline. A digital radiograph was taken after a 6# K file was placed to the working length in the mesiobuccal canal.Based on their weights, the samples were dispersed equally across the sixgroups (n=20). They looked inside them to ensure that the root morphology was normal and that the canal was open and free of any abnormalities, damage, or fillings. They looked at the curvature of the mesial root and chose samples with a curvature of 20-35 degrees. The mesial roots were dissected, labeled, and put in a different location. Results Overall, the experimental group'sincidence of buccolingual fractures was 55%, making it the most prevalent fracture type. The mesiodistal type of fracture had a 35% incidence rate, which was the second most prevalent. We found that comminuted and transverse fractures occurred in only 15% and 5% of patients, respectively, of all fractures.Both the test and the control groups had a disproportionately high number of buccolingual fractures. When comparing the root fracture loads of the two experimental groups, there was no significant difference (p>0.05) Conclusion Within this study's restrictions and standardization techniques, it can be concluded that the single file system-prepared roots' resistance to fracture was comparable to that of the control group. It is recommended to conduct additional research on these single file systems using different metrics and to assess them in a clinical setting.

Events always take (place with) ser

Abstract The present study aims to throw light on the behavior of the Spanish copulas ser and estar in locative sentences, beyond their classical distinction in terms of Individual-Level (IL) versus Stage-Level (SL) predicates. The behavior of the Spanish copulas in locative contexts constitutes an oddity that we aim to probe here: events (concierto ‘concert’), despite their clear spatial and temporal anchorage, combine with ser (El concierto es en París ‘The concert is in Paris’), which is the copula typically associated with IL or permanent predicates. To do so, we discuss the behavior of copulas as locative verbs in a broader empirical context, where not just events and individuals are considered, but also other types of nominals, such as qualities and states. We argue that ser emerges with events because time and place constituents combine directly with events, without the intermediation of extra predicational structure. When carrying a marked value, that extra predicational structure triggers the insertion of estar; when there is no predication structure (such as with events) and when the predication structure is unmarked (IL predicates), ser appears as the default copula.

Optical and Color Properties of Gamma Irradiated Polyvinyl Alcohol - Sodium lignosulfonate-Cadmium sulfide Nanocomposite Films

We prepared a nanocomposite (NC) film containing sodium lignosulfonate (LS), polyvinyl alcohol (PVA) and nano-sized cadmium sulfide (CdS) using the thermolysis and ex-situ casting procedures. Samples from the prepared PVA-LS/CdS NC film were exposed to gamma radiation doses (2 − 20 kGy). To study the resultant outcome of the gamma ray irradiation on the optical and color properties of the synthesized NCs, we used UV-vis spectroscopy and the International Commission on Illumination (CIE) color changes technique. When the gamma dose was increased to 20 kGy, the refractive index increased along with a decrease in the direct optical bandgap from 4.41 to 3.90 eV. We attribute this to the dominance of crosslinking that damaged the ordered configuration and thus increased the amorphous phase. This suggests that the gamma radiation can facilitate the spreading of CdS within the composite matrix suggesting an extra compacted structure of the PVA-LS/CdS NC samples. Moreover, the values of Eg, obtained from ε″ vs. energy plots were close to those values obtained by means of Tauc’s relation, indicating that the NC films exhibited a direct allowed transition. Finally, the color changes between the pristine and irradiated samples were characterized. The pristine PVA-LS/CdS NC film exhibited substantial color differences.

Degenerations of bundle moduli

Over a family X of complete curves of genus g, which gives the degeneration of a smooth curve into one with nodal singularities, we build a moduli space which is the moduli space of holomorphic SL(n,C) bundles over the generic smooth curve Xt in the family, and is a moduli space of bundles equipped with extra structure at the nodes for the nodal curves in the family. This moduli space is a quotient by (C⁎)s of a moduli space on the desingularization. Taking a “maximal” degeneration of the curve into a nodal curve built from the glueing of three-pointed spheres, we obtain a degeneration of the moduli space of bundles into a (C⁎)(3g−3)(n−1)-quotient of a (2g−2)-th power of a space associated to the three-pointed sphere. Via the Narasimhan-Seshadri theorem, the moduli space of SL(n,C) bundles on the smooth curve is a space of representations of the fundamental group into SU(n) (the “symplectic picture”). We obtain the degenerations also in this symplectic context, in a way that is compatible with the holomorphic degeneration, so that our limit space is also a (S1)(3g−3)(n−1) symplectic quotient of a (2g−2)-th power of a space associated to the three-pointed sphere.

Extra structure on the cohomology of configuration spaces of closed orientable surfaces

The rational homology of unordered configuration spaces of points on any surface was studied by Drummond-Cole and Knudsen. We compute the rational cohomology of configuration spaces on a closed orientable surface, keeping track of the mixed Hodge numbers and the action of the symplectic group on the cohomology. We find a series with coefficients in the Grothendieck ring of sp(2g) that describes explicitly the decomposition of the cohomology into irreducible representations. From that we deduce the mixed Hodge numbers and the Betti numbers, obtaining a new formula without cancellations.

Design of Self-Decoupling Dielectric Resonator Antenna With Shared Radiator

The method of mode cancellation to design a two-port dielectric resonator antenna (DRA) for an in-band full-duplex (IBFD) application is investigated in this communication. The whole antenna structure is straightforward, only composed of a single DRA element, a pair of feeding lines, and a pair of metallic probes. Attributing to the features of different modes used in this design, mutual coupling between the exciting port and the passive port can be suppressed to an extremely low level without using an extra decoupling structure. A prototype is fabricated and measured for verification. The measured results demonstrate that the proposed antenna has broad bandwidth and high isolation level can be achieved throughout the whole working band.

Quantum sets of the multicolored-graph approach to contextuality

The CHSH inequalities are the most famous examples of Bell inequalities. Cabello, Severini, and Winter (CSW) came up with a graph approach to noncontextuality inequalities, which connects some graph-theoretic concepts to quantum and classical correlations. For example, the theta body of the exclusivity graph can be associated with the set of correlations achieved by quantum theory. Following the CSW approach, one may think that the theta body of the CHSH graph, is equal to the quantum set of the CHSH Bell inequality, but is this really true? All assumptions about the CHSH inequalities come from Bell scenarios, while CSW approach only demands the exclusivity structure of a non-contextuality (NC) scenario. To deal with the extra structure related to the presence of different players in a Bell scenario like CHSH, the colored-graph approach was introduced. Does it make any difference to think about CHSH as a Bell scenario or a more general NC scenario? The Bell CHSH inequality is represented by a bicolored graph and the NC CHSH inequality by a simple graph, which is the shadow of the colored graph. In general, we have that the theta body of the colored graph is a subset of the theta body of its shadow graph in the same way that the Lov\`asz number, which corresponds to the quantum bound, of the simple graph is greater than or equal to the Lov\`asz number of the colored graph. In the case of the CHSH inequality, we have that the Lov\`asz numbers are equal. Does this accident also hold for the corresponding quantum sets? Is it true that the theta bodies are equal, which would mean that every correlation reached by quantum theory applied to the CHSH NC scenario could also be obtained at the in principle more restrictive CHSH Bell scenario? In this paper our answer to such a question is negativ. This implies that there are quantum correlations which can not be obtained under Bell restrictions.

Compact Dual Circularly-Polarized Quad-Element MIMO/Diversity Antenna for Sub-6 GHz Communication Systems.

In this paper, a compact dual circularly-polarized (CP) planar multiple-input-multiple-output (MIMO) antenna is presented for a sub-6 GHz frequency band. The antenna consists of four identical resonating elements, which are placed in a mirrored-image pattern to obtain polarization diversity. Element 2 is a mirror image of element 1, and elements 3 and 4 are mirror images of elements 1 and 2. Each antenna element comprises an elliptical resonator, a 50-Ω microstrip feed line, and a rectangular stub integrated with the feed to increase the surface current path of the antenna, shifting the resonating frequency to the lower side. Additionally, the rectangular stub is lengthened towards the right side (along the +x-axis direction in the antenna element 1), which balances the magnitude and 90° phase variance among the horizontal (Ex) and vertical (Ey) fields. The proposed MIMO antenna supports both types of circular polarization, where radiators 1 and 3 radiate right-hand CP (RHCP) rays and radiators 2 and 4 radiate left-hand CP (LHCP) rays. Developing a compact-size MIMO antenna is a challenging task, especially when the antenna elements share the same ground plane and are placed less than half a wavelength apart. The mutual coupling in the proposed antenna is reduced by increasing the spacing between the elements without the use of any extra decoupling structure. Optimal spacing is maintained to achieve compact geometry with less inter-element correlation. The radiators are closely placed with an edge-to-edge spacing of 0.08λ0, where λ0 is the free space wavelength at 3.6 GHz. A peak gain of 5 dBi, efficiency of 90%, an envelope correlation coefficient (ECC) of less than 0.1, and isolation of more than 18 dB are obtained between different ports of the prototype antenna. The overall size of the antenna element is 17 mm × 17 mm × 1.6 mm, and the MIMO antenna is 40 mm × 40 mm × 1.6 mm.

Variable Selection of Spatial Logistic Autoregressive Model with Linear Constraints.

In recent years, spatial data widely exist in various fields such as finance, geology, environment, and natural science. These data collected by many scholars often have geographical characteristics. The spatial autoregressive model is a general method to describe the spatial correlations among observation units in spatial econometrics. The spatial logistic autoregressive model augments the conventional logistic regression model with an extra network structure when the spatial response variables are discrete, which enhances classification precision. In many application fields, prior knowledge can be formulated as constraints on the parameters to improve the effectiveness of variable selection and estimation. This paper proposes a variable selection method with linear constraints for the high-dimensional spatial logistic autoregressive model in order to integrate the prior information into the model selection. Monte Carlo experiments are provided to analyze the performance of our proposed method under finite samples. The results show that the method can effectively screen out insignificant variables and give the corresponding coefficient estimates of significant variables simultaneously. As an empirical illustration, we apply our method to land area data.