Side Of Substrate Research Articles

Protein Engineering of Substrate Specificity toward Nitrilases: Strategies and Challenges.

Nitrilase is extensively applied across diverse sectors owing to its unique catalytic properties. Nevertheless, in industrial production, nitrilases often face issues such as low catalytic efficiency, limited substrate range, suboptimal selectivity, and side reaction products, which have garnered heightened attention. With the widespread recognition that the structure of enzymes has a direct impact on their catalytic properties, an increasing number of researchers are beginning to optimize the functional characteristics of nitrilases by modifying their structures, in order to meet specific industrial or biotechnology application needs. Particularly in the artificial intelligence era, the innovative application of computer-aided design in enzyme engineering offers remarkable opportunities to tailor nitrilases for the widespread production of high-value products. In this discussion, we will briefly examine the structural mechanism of nitrilase. An overview of the protein engineering strategies of substrate preference, regioselectivity and stereoselectivity are explored combined with some representative examples recently in terms of the substrate specificity of enzyme. The future research trends in this field are also prospected.

Microstructure and mechanical properties of the wire arc additively manufactured 316L/ER70S-6 bimetal structure

ABSTRACT The wire arc additive manufacturing (WAAM) process often begins printing on a substrate. In some cases, the substrate could act as a functional part of the WAAM-fabricated parts. In this work, ER70S-6 is directly deposited onto a 316L substrate using the WAAM process. Microstructural studies reveal good fusion and bonding at the interface. Due to the dilution of ER70S-6 and 316L, a gradient change in composition and microstructure was observed in the first six layers. The first layer (Fe-10Cr-5.5Ni-1Mo-1Mn) and the second layer (Fe-4Cr-2Ni-1Mn-0.5Mo) exhibit a bainite microstructure. Ferritic grains were observed from the third layer onwards. The microhardness is high at 336.9 ± 6.3 HV for the first layer and 302.7 ± 5.7 HV for the second layer. A decrease in microhardness was observed with the increase of the building layer until layer six. The yield strength is 356.6 MPa and the UTS is 502.3 MPa for the 316L/ER70S-6 bimetal joint. The digital image correlation (DIC) method is used to analyse the deformation behaviour. During the tensile test, the 316L substrate side yields first, and then the deformation shifts to the ER70S-6 side. This study also holds the potential for the development of novel alloys.

High-Isolation Array Antenna Design for 5G mm-Wave MIMO Applications

A low form-factor design of an eight-element antenna array is presented for 5G mm-wave MIMO applications. The design features modified circular patch radiators that achieve an impedance bandwidth of 2.6 GHz, covering frequencies from 37.7 to 40.3 GHz. The radiating elements are strategically arranged on opposite sides of a common substrate and interleaved to significantly reduce mutual coupling between adjacent elements. This innovative technique effectively minimizes coupling between the array’s radiators without the need of a decoupling structure. The MIMO antenna is fabricated on a low-loss Rogers-5880 substrate, with a thickness of 0.8 mm, a dielectric constant of 2.2, and a loss tangent of 0.0009, ensuring minimal signal loss and confirming the accuracy of simulation results. The inter-element isolation exceeds 25 dB, and the array provides a gain greater than 6 dBi, with a peak gain of 7.5 dBi at 39 GHz. This high gain enhances the antenna’s ability to mitigate atmospheric attenuation at higher frequencies, making it highly suitable for 5G mm-wave applications.

Flexible bezel‐less thin‐film transistor backplane with through‐plastic‐vias for seamless tiling

AbstractTiling with a variety of panel units is a promising approach to customizing displays in terms of size, shape, and aspect ratio. However, tiled displays with conventional panel units have a major drawback in that they suffer from noticeable seams due to the bezels of the panel units. Here, we demonstrate a flexible bezel‐less thin‐film transistor (TFT) backplane for seamless tiling. By using through‐plastic‐vias (TPVs) that penetrate an ultrathin polyimide (PI) film substrate, a bezel‐less backplane with an ultra‐narrow bezel width of 8 μm was realized, in which oxide TFTs in pixel circuits on the backplane are driven from the back side of the PI film substrate using three‐dimensional signal wires, which go through the TPVs. The resistance of a TPV was evaluated with a TPV chain with 1000 TPVs connected in series and was found to be as small as 1.3 Ω. Furthermore, the transfer characteristics of an oxide TFT in a test element group for a pixel circuit were evaluated from the back side of the PI film substrate. The TFT exhibited clear switching behavior with an on/off current ratio of more than 108 and a high mobility of 25 cm2/Vs, which are sufficient to drive light‐emitting devices.

Mn Oxide / IrO2 / Ti Anodes Prepared By Calcination for Oxygen Evolution in Seawater Electrolysis

INTRODUCTIONIn the future, hydrogen production will be performed by direct electrolysis of seawater. However, every time hydrogen is produced, it is necessary to avoid generating chlorine because it has a negative impact on the ecosystem. We have been developing an oxygen evolution anode for seawater electrolysis that produces only oxygen without chlorine. It has been found that anodically deposited g-MnO2-type Mn1-xMoxSnyO2+xanodes showed the oxygen evolution efficiency for more than 4000 hours in the electrolysis of 0.5 M NaCl [1]. The anodic deposition method has required many steps and further cleaning of the electrolytic diaphragm. For these reasons, in order to commercialize oxygen evolution anodes for seawater electrolysis, it is essential to establish a simple manufacturing method. We are considering fabricating Mn oxide as an active material on an IrO2 intermediate layer formed on a titanium substrate using calcination method.In this study, Mn oxide electrodes were fabricated by coating various concentrations of manganese nitrate butanol solutions on the IrO2intermediate layer and at various calcination temperatures. We have investigated the crystal structure and Mn oxide weight that would have the highest activity for oxygen evolution efficiency.EXPERIMENTALTitanium metal substrates were immersed to roughen enhancing the anchor effect of the substrate on the electrocatalyst layer in concentrated H2SO4. IrO2 intermediate layer was formed by coating on one side of the titanium substrate in 0.26 M Chloroiridic acid with a brush, dried at 363 K for 10 min in air. The other side was coated in the same procedure and dried. And then these substrates was calcined at 723 K for 10 min in air. This procedure was repeated three times but the final calcination of the specimen was continued for 60 min at 723 K in air for calcination. Mn oxide electrocatalyst for oxygen evolution was formed by coating on the IrO2 / Ti in 0.073～0.52 M Mn(NO3)2 butanolsolution with a brush and drying at 353 K for 90 min in the same way as when forming the IrO2 intermediate layer. Calcination was performed at 473, 573, and 723 K. Impurities formed without becoming manganese oxides were electrolytically cleaned in 0.5 M NaCl until no dissolution of the impurities was observed.The performance of the electrode was examined by electrolysis of 0.5 M NaCl solution at 1000Am-2. The oxygen evolution efficiency was estimated by the difference between the total charge passed during electrolysis and the formation charge of chlorine analyzed by iodometric titration. Polarization curves were measured galvanostatically. Correction for IR drop was made with the electrochemical impedance spectroscopy (EIS) method.The characterization of the electrode was carried out by XRD and EPMA.RESULTS AND DISCUSSIONXRD diffraction clarified that Mn₂O₃ were consisted at 723 K, Ramsdellite-type MnO₂ at 673 K, and IrO2 at 573 K.Figure 1 shows the relationship between Mn oxide weight and oxygen evolution efficiency. The oxygen evolution efficiency of the anode consisted of only IrO2 was about 8%. It found that the oxygen evolution efficiency was different due to the difference in calcination temperature, that is, the difference in crystal structure to Mn oxide weight of about 2.5 mgcm-2. The oxygen evolution efficiency of the anode with Ramsdellite-type MnO₂ formed at 573 K was about 57 % at 1.8 mgcm-2. The oxygen evolution efficiency of anodes formed at 473 and 723 K with the equivalent weight was about 52 and 32 % respectively. Previous research has shown that anodes containing the γ-MnO2 formed by anodic deposition have high catalytic activity for oxygen evolution [2]. The γ-MnO2 contains stacking faults in which β-MnO2 is mixed into the ramsdellite-MnO2[3]. The electrode with 4.5 mgcm-2 of Mn₂O₃ at 723 K shows the maximum oxygen generation efficiency, which is about 83%.A future challenge is to add substances such as molybdenum as additional elements to obtain higher oxygen evolution efficiency. In conventional electrode fabrication using anodic deposition, the addition of molybdenum significantly has improved oxygen generation efficiency.REFERENSE[1]Z. Kato, J. Bhattarai , N. Kumagai, K. Izumiya, and K. Hashimoto, Applied. Surface. Science. 257 (2011) 8230.[2] A. A. El-Moneim, N. Kumagai, K. Asami, and K. Hashimoto , Materials Transactions, Vol. 46, No. 2 (2005) pp. 309[3] Jian-Bao LI, K. Koumoto and H. Yanagida, Journal of the Ceramic Society of Japan, 96 [1] (1988)74 Figure 1

Unexpected dual cracks in chip-ceramic substrate interconnect: Unveiling the mechanism behind simultaneous cracking at both the top and bottom of a solder joint

Chip-ceramic interconnect is increasingly vital in high-density IC especially in high-frequency applications, making the reliability of solder joints with underfill material in this case a significant concern. In this study, unexpected simultaneous cracking at both the top and bottom of a solder joint was noted after 500 thermal cycles. Crack 1 propagated along Ti/Pt/Au/SAC305 interface on Si chip side while crack 2 propagated along the solder/IMC interface on AlN HTCC substrate side, which significantly contrasted with prior researches based on FR4 substrate where single cracking typically occurred at one interface. The emergence of two cracks was attributed to tensile stress induced by CTE disparities among different components, including the underfill, which caused two stress interfaces. The FEA results indicated higher stress and strain levels on FR4 substrate compared to AlN, thus facilitating easier crack initiation and more severe crack propagation. The nanoindentation results showed a difference in elastic modulus between the IMC and β-Sn phases, leading to stress concentration during thermal cycling which initiated crack. The increased brittleness of IMC contributed to partial penetration of the crack into the IMC layer during propagation. A strategy to enhance the reliability of the solder joint was also proposed.

Carrier Mobility Enhancement in Ultrathin-Body InGaAs-on-Insulator n-Channel Metal-Oxide-Semiconductor Field-Effect Transistors Based on Dual-Gate Modulation

As a promising candidate for More Moore technology, InGaAs-based n-channel metal-oxide-semiconductor field-effect transistors (nMOSFETs) have attracted growing research interest, especially with InGaAs-on-insulator (InGaAs-OI) configurations aimed at alleviating the short channel effects. Correspondingly, the fabrication of an ultrathin InGaAs body becomes necessary for the full depletion of the channel, while the deteriorated semiconductor–insulator interface-related scattering could severely limit carrier mobility. This work focuses on the exploration of carrier mobility enhancement strategies for 8 nm body-based InGaAs-OI nMOSFETs. With the introduction of a bottom gate bias on the substrate side, the conduction band structure in the channel was modified, relocating the carrier wave function from the InGaAs/Al2O3 interface into the body. Resultantly, the channel mobility with an inversion layer carrier concentration of 1 × 1013 cm−2 was increased by 62%, which benefits InGaAs-OI device application in monolithic 3D integration. The influence of the dual-gate bias from front gate and bottom gate on gate stability was also investigated, where it has been unveiled that the introduction of the positive bottom gate bias is also beneficial for gate stability with an alleviated orthogonal electric field.

Adaptation of a Differential Scanning Calorimeter for Simultaneous Electromagnetic Measurements.

Although much information can be gained about thermally induced microstructural changes in metals through the measurement of their thermophysical properties using a differential scanning calorimeter (DSC), due to competing influences on the signal, not all microstructural changes can be fully characterised this way. For example, accurate characterisation of recrystallisation, tempering, and changes in retained delta ferrite in alloyed steels becomes complex due to additional signal changes due to the Curie point, oxidation, and the rate (and therefore the magnitude) of transformation. However, these types of microstructural changes have been shown to invoke strong magnetic and electromagnetic (EM) responses; therefore, simultaneous EM measurements can provide additional complementary data which can help to emphasise or deconvolute these complex signals and develop a more complete understanding of certain metallurgical phenomena. This paper discusses how a DSC machine has been modified to incorporate an EM sensor consisting of two copper coils printed onto either side of a ceramic substrate, with one coil acting as a transmitter and the other as a receiver. The coil is interfaced with a custom-built data acquisition system, which provides current to the transmit coil, records signals from the receive coil, and is controlled by a graphical user interface which allows the user to select multiple excitation frequencies. The equipment has a useable frequency range of approximately 1-100 kHz and outputs phase and magnitude readings at a rate of approximately 50 samples per second. Simultaneous DSC-EM measurements were performed on a nickel sample up to a temperature of 600 °C, with the reversable ferromagnetic to paramagnetic transition in the nickel sample invoking a clear EM response. The results show that the combined DSC-EM apparatus has the potential to provide a powerful tool for the analysis of thermally induced microstructural changes in metals, feeding into research on steel production, development of magnetic and conductive materials, and many more areas.

Efficient Redirection of Trapped Broad-Band Fluorescence from Substrates into Free Space Using c-Si Metasurfaces.

Fluorescent dye films on transparent substrates are essential for OLEDs, flexible displays, X-ray detection, and wireless optical communications. However, their efficiency is often hampered by fluorescence trapping due to total internal reflection (TIR) and waveguiding. This study tackles this longstanding challenge by reconceptualizing the integration of dye films with nanoantenna metasurfaces. Traditional methods involve directly spin-coating films onto c-Si metasurfaces on quartz substrates, resulting in edge luminescence and weak inner signals. We present a straightforward, adjustable approach by integrating dye films on the opposite side of quartz substrates, reaching a 2.5-fold photoluminescence enhancement and improving the uniformity of the emission compared to the conventional methods. These gains stem from redirecting a significant portion of leaked fluorescence light trapped inside the substrate into free space, surpassing TIR conditions through in-plane diffraction orders of the metasurfaces across the full RGB spectrum. Our findings facilitate the design of more efficient luminescent devices.

Design of Compact Dielectric Metalens Visor for Augmented Reality Using Spin-Dependent Supercells

Augmented reality overlays computer-generated virtual information onto real-world scenes, enhancing user interaction and perception. However, traditional augmented reality optical systems are usually large, bulky, and have limited optical performance. In this paper, we propose a novel compact monochrome reflective dielectric metalens visor with see-through properties, engineered using a periodic structure of spin-dependent supercells. The supercell, which is composed of staggered twin nanofins, provides spin-dependent destructive or constructive interference with different circularly polarized incidences. The design combines the principles of interference with the Pancharatnam–Berry phase to enhance reflection at a working wavelength of 650 nm while maintaining good transmission. Right circularly polarized light incident from the substrate side causes destructive interference, enabling the supercell to work in reflection mode, while left circularly polarized light causes constructive interference, enabling the supercell to work in transmission mode. Furthermore, the supercell-constructed metalens can achieve near-diffraction-limited reflective focusing and a broad diagonal field of view of approximately 96°. In addition, compared to transmissive metalens visors, the reflective design eliminates the need for a beam splitter, significantly reducing the size and weight of the system. Our work could facilitate the development of compact and lightweight imaging systems and provide valuable insights for augmented reality near-eye display applications.

Crystal structure and enzyme engineering of the broad substrate spectrum l-amino acid oxidase 4 from the fungus Hebeloma cylindrosporum.

l-Amino acid oxidases (LAAOs) catalyze the oxidative deamination of l-amino acids to α-keto acids. Recombinant production of LAAOs with broad substrate spectrum remains a formidable challenge. We previously achieved this for the highly active and thermostable LAAO4 of Hebeloma cylindrosporum (HcLAAO4). Here, we crystallized a proteolytically truncated surface entropy reduction variant of HcLAAO4 and solved its structure in substrate-free form and in complex with diverse substrates. The ability to support the aliphatic portion of a substrate's side chain by an overall hydrophobic active site is responsible for the broad substrate spectrum of HcLAAO4, including l-amino acids with big aromatic, acidic and basic side chains. Based on the structural findings, we generated an E288H variant with increased activity toward pharmaceutical building blocks of high interest.

Brazing mechanism and shear strength of SiAlON/WC‐Co joint using Ag–Cu–Ti active filler

AbstractThis work investigated the formation mechanism and the effects of temperature on the microstructure and shear strength of vacuum‐brazed SiAlON ceramic/WC‐Co cemented carbide joints using an Ag–Cu–Ti active filler as the interlayer. The diffusion of Ti elements toward substrates and their subsequent reaction during the brazing process led to the formation of TiN, TiC, and Ti5Si3 phases, where the featured reaction layers were established. A continuous reaction layer of TiN in the SiAlON substrate side and TiC in the WC substrate side were formed. The ceramic phases (Ti5Si3 TiN, and TiC) were distributed in a brazed intermediate layer. The highest shear strength of the brazed joints obtained at 850°C was 325.28 ± 20.27 MPa, demonstrating the feasibility of the Ag–Cu–Ti active filler in producing robust joints.

Development of a hydrogen permselective silica membrane and its application to the thermochemical water splitting method

Abstract The thermochemical water splitting IS process is one of the hydrogen production method to use a heat directly. The temperature of the thermal decomposition of water (4000 K) can be reduced under 700 K by introducing I2 and SO2 as recycling catalysts. One of the problems in the IS process is that the conversion of the HI decomposition reaction is low at about 20%. If a membrane reactor with the H2 permselective membrane is applied to the HI decomposition reaction, the hydrogen can be extracted to improve the HI conversion. We focus on a counter diffusion CVD method for the preparation method of the membranes. Two reactants (e.g. silica precursor and oxidant) are provided at the opposite side of the porous substrates and hybrid silica is deposited inside the pore of the substrate. The pore sizes are controlled by introducing organic functional groups to silica precursor. In this study, the silica hybrid membrane with high H2 permeation performance and high H2/HI selectivity were developed by introducing organic functional groups. Effects of the organic functional groups were summarized by using a pore model. The HI gas and other inorganic gases permeation performance were tested through silica hybrid membranes.

Study on the Conductivity Effect on the Characteristics of a Wideband Printed Dipole Antenna Implemented with Silver Nanoparticle Ink

This study examined a flexible composite wideband dipole antenna implemented with conductive silver nanoparticle ink having different conductivities. Two identical split ring resonators (SRRs) were designed to encompass each arm of a dipole element, and each dipole arm and its coupled SRR were printed on the top and bottom sides of a dielectric substrate. The overall dimensions of the compact antenna were 10 mm × 74.8 mm × 0.254 mm (0.053λo × 0.399λo × 0.0014λo at 1.6 GHz). The characteristics of the antenna with different conductivities were numerically investigated and experimentally confirmed. Our investigation aimed to ascertain the proposed antenna's response to different conductivity values and to determine the range of conductivity values that generates major changes in the antenna's performance characteristics in terms of impedance bandwidth, gain, and radiation efficiency. At conductivity values less than approximately 6.0 × 104 S/m, the number of generated resonances changed from three to two, and the antenna experienced a nearly 3-dB gain reduction when the conductivity approached 5.8 × 104 S/m.

Diffusion Barrier Performance of Ni-W Layer at Sn/Cu Interfacial Reaction.

As the integration of chips in 3D integrated circuits (ICs) increases and the size of micro-bumps reduces, issues with the reliability of service due to electromigration and thermomigration are becoming more prevalent. In the practical application of solder joints, an increase in the grain size of intermetallic compounds (IMCs) has been observed during the reflow process. This phenomenon results in an increased thickness of the IMC layer, accompanied by a proportional increase in the volume of the IMC layer within the joint. The brittle nature of IMC renders it susceptible to excessive growth in small-sized joints, which has the potential to negatively impact the reliability of the welded joint. It is therefore of the utmost importance to regulate the formation and growth of IMCs. The following paper presents the electrodeposition of a Ni-W layer on a Cu substrate, forming a barrier layer. Subsequently, the barrier properties between the Sn/Cu reactive couples were subjected to a comprehensive and systematic investigation. The study indicates that the Ni-W layer has the capacity to impede the diffusion of Sn atoms into Cu. Furthermore, the Ni-W layer is a viable diffusion barrier at the Sn/Cu interface. The "bright layer" Ni2WSn4 can be observed in all Ni-W coatings during the soldering reflow process, and its growth was almost linear. The structure of the Ni-W layer is such that it reduces the barrier properties that would otherwise be inherent to it. This is due to the "bright layer" Ni2WSn4 that covers the original Ni-W barrier layer. At a temperature of 300 °C for a duration of 600 s, the Ni-W barrier layer loses its blocking function. Once the "bright layer" Ni2WSn4 has completely covered the original Ni-W barrier layer, the diffusion activation energy for Sn diffusion into the Cu substrate side will be significantly reduced, particularly in areas where the distortion energy is concentrated due to electroplating tension. Both the "bright layer" Ni2WSn4 and Sn will grow rapidly, with the formation of Cu-Sn intermetallic compounds (IMCs). At temperatures of 250 °C, the growth of Ni3Sn4-based IMCs is controlled by grain boundaries. Conversely, the growth of the Ni2WSn4 layer (consumption of Ni-W layer) is influenced by a combination of grain boundary diffusion and bulk diffusion. At temperatures of 275 °C and 300 °C, the growth of Ni3Sn4-based IMCs and the Ni2WSn4 layer (consumption of Ni-W layer) are both controlled by grain boundaries. The findings of this study can inform the theoretical design of solder joints with barrier layers as well as the selection of Ni-W diffusion barrier layers for use in different soldering processes. This can, in turn, enhance the reliability of microelectronic devices, offering significant theoretical and practical value.

Characterizing electric fields in semiconductor devices: effect of second-harmonic light interference.

Characterizing electric fields in semiconductor devices using electric field-induced second-harmonic generation (EFISHG) has opened new opportunities for an advanced device design. However, this new technique still has challenges due to the interference between background second-harmonic generation (SHG) and EFISHG generated light. We demonstrate that interference effects can effectively be eliminated during EFISHG measurements by focusing the laser from the transparent substrate side of a GaN PN diode, enabling straightforward quantitative electric field analysis, in contrast to PN junction interface side measurements. A model based on wave generation and propagation is proposed and highlights the incoherence between background SHG and EFISHG light. This incoherence may be attributed to the depth of focus of the incident laser and phase mismatch between incident and SHG light.

The detection of blood, semen and saliva through fabrics: A pilot study

This study aimed to identify if biological material could be detected on the opposite side to deposition on fabric by commonly used presumptive and/or secondary tests. Additionally, this study aimed to ascertain if there is a difference in the DNA quantity and quality from samples obtained from both sides of the same substrate: cotton, polyester, denim, or combined viscose and polyester swatches. Blood, semen, or saliva (25 μL) was deposited on one side of 5 replicates of each fabric type and left for 24 h. Blood swatches were tested using Hemastix® and the ABACard® HemaTrace® immunoassay, semen swatches were tested using acid phosphatase (AP) reagent, the ABACard® p30® immunoassay and hematoxylin and eosin staining, and saliva swatches were tested using Phadebas® paper and the RSID-Saliva™ immunoassay. Both sides of each swatch were separately wet/dry swabbed and subjected to DNA analysis. Blood was able to be detected on the underside of all fabrics using both tests. Semen was able to be detected on the underside of swatches using the presumptive AP test but not p30®, and sperm was rarely observed. Saliva was able to be detected by RSID-Saliva™ but not Phadebas® paper when the underside of swatches were tested. Across all biological materials, DNA was able to be recovered from the top side of all 60 swatches. For the underside, DNA was able to be recovered from 54 swatches. Of the 6 swatches that DNA was unable to be recovered from, one sample was from semen and the rest were from saliva. This study has demonstrated that DNA and components of interest in forensically relevant biological material can be recovered from the opposite side to where it was originally deposited, and that observing biological material and/or DNA on one side of fabric does not definitively indicate direct deposition on that side.

A self-heating gas sensor for online monitoring of endogenous ethylene of post-harvest cut chrysanthemums

The decay of post-harvest cut chrysanthemums (PHCCs) during storage and shipment results in enormous loss, and the accumulated endogenous ethylene is one of the main reasons. However, it is challenging for current technologies to onsite monitoring of endogenous ethylene of PHCCs whose concentration is very low. Here, we propose a ethylene sensor with high performances enabled by self-heating capability. Specifically, laser-induced graphene (LIG) patterns are in-situ fabricated on the upper and lower sides of a polyimide substrate. The upper LIG is coated with chemo-resistive SnO2 for ethylene sensing and the lower LIG serves as heater for self-heating. The working temperature is well tuned by the heater and effectively transferred to SnO2. Owing to the self-heating capability, the sensor displays outstanding ethylene detection performances, such as ultra-low limit of detection (1.654 ppb), wide detection range (0.05–100 ppm), high sensitivity (0.2249 ppm−1), high detection linearity (0.9925), and long-term stability (>14 days). Moreover, the sensor is integrated with a data acquisition circuit and connected to a mobile application, realizing online monitoring of endogenous ethylene of PHCCs. The results demonstrate that the decay of PHCCs is accelerated as the endogenous ethylene accumulates. This work would promote the online monitoring of endogenous ethylene of plants.

Wideband shared-aperture orthogonal mode antenna pair for MIMO application

A wideband shared-aperture antenna is designed for MIMO application based on asymmetric orthogonal-mode antenna pair. A symmetric T-shaped antenna and an asymmetric double-L-shaped antenna constitute the proposed antenna pair. Two co-planar antenna elements are configured above the ground (on the same substrate side). The wideband self-decoupling characteristic of the antenna pair is achieved via orthogonal modes. The proposed shared-aperture antenna demonstrates good impedance matching, high isolation, and good diversity performance over a bandwidth of 3.04–5.28 GHz, covering the 5G N77/N78/N79 bands, which is suitable for compact 5G MIMO terminals. Two such antenna pairs are arranged along the upper side of the ground to construct a 4-port MIMO antenna. The proposed MIMO antenna is fabricated and tested to verify its performance. Favorable results are realized, including impedance matching, isolation, efficiency, and ECC. The measured results are in good agreement with the simulated results.

Miniaturized Vivaldi antenna with multiband and high-gain for millimeter-wave applications

ABSTRACT A novel miniaturised quad-band printed Vivaldi antenna is proposed for millimetre-wave applications. It can be seen as a two-arm antenna where the antenna arms bound the tapered Vivaldi slot. The antenna arms are printed on the opposite sides of a flexible millimetre-wave substrate. Three periodic structures are added to the antenna geometry and printed in the area surrounding the radiating slot structure to improve the impedance matching over the antenna’s four operational frequency bands and enhance the gain. These periodic structures are parasitic ring array loaded to the antenna arms, ring-array reflector inserted between the antenna arms and the ground plane, and metamaterial director printed in front of the antenna arms. A prototype of the proposed antenna is fabricated for experimental assessment of the antenna performance. The experimental measurements show good agreement with the simulation results. The proposed antenna impedance is matched over the four frequency bands centred at 25 , 35 , 45 , and 55 GHz . The bandwidth of each operational band is about 5 GHz with percent bandwidths of 20 % , 15 % , 11 % , and 9 % , respectively. The corresponding values of the maximum gain are 7.5 , 10.5 , 12 , and 13 dBi , respectively. The radiation efficiency is maintained above 93 % over the entire frequency band (20–60 GHz).