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[Display omitted] • P450Rdb compiles a comprehensive catalog of over 1,600 reactions catalyzed by P450s. • P450Rdb has collected a diverse collection of more than 590 P450s from over 200 species. • P450Rdb systematically organizes all reactions based on their chemical reaction type and site. • P450Rdb provides a user-friendly interface on P450s and their associated reactions. • P450Rdb is beneficial for research in synthetic biology, pharmacology, and the chemical industry. Cytochrome P450 enzymes (P450s) are recognized as the most versatile catalysts worldwide, playing vital roles in numerous biological metabolism and biosynthesis processes across all kingdoms of life. Despite the vast number of P450 genes available in databases (over 300,000), only a small fraction of them (less than 0.2 %) have undergone functional characterization. To provide a convenient platform with abundant information on P450s and their corresponding reactions, we introduce the P450Rdb database, a manually curated resource compiles literature-supported reactions catalyzed by P450s. All the P450s and Reactions were manually curated from the literature and known databases. Subsequently, the P450 reactions organized and categorized according to their chemical reaction type and site. The website was developed using HTML and PHP languages, with the MySQL server utilized for data storage. The current version of P450Rdb catalogs over 1,600 reactions, involving more than 590 P450s across a diverse range of over 200 species. Additionally, it offers a user-friendly interface with comprehensive information, enabling easy querying, browsing, and analysis of P450s and their corresponding reactions. P450Rdb is free available at http://www.cellknowledge.com.cn/p450rdb/. We believe that this database will significantly promote structural and functional research on P450s, thereby fostering advancements in the fields of natural product synthesis, pharmaceutical engineering, biotechnological applications, agricultural and crop improvement, and the chemical industry. [ABSTRACT FROM AUTHOR]

In many fields, e.g., ground-penetrating radar and ultra-wideband radiation, a high-pulse-repetition-frequency (PRF) and high-time-base-stability sub-nanosecond pulser is required, and its output waveform should be close to a gaussian pulse. In this article, the transistorized pulser is studied and optimized to improve its output parameters. The printed circuit board circuit parameters of the pulser are first optimized, which is beneficial for the amplitude and the rise time. To improve the time base stability, the collector voltage ramp triggering mode is adopted to replace the conventional base triggering mode for the pulser. For higher PRF, the pulser with the capacitance–transistor parallel structure is immersed in the fluorinert liquid. Moreover, the deficit-charge method is adopted, and small charging capacitances are used in the last few stages to weaken the oscillation in the pulse falling edge. From experimental results, the amplitude of the optimized pulser is 1.35 kV, its rise time is reduced from about 200 to 135 ps, the maximum PRF is improved from 250 to 500 kHz, the pulse jitter is reduced to 22 ps, and the pulse drift is reduced from hundreds of ps/min to 47 ps/min. Meanwhile, the oscillation in its falling edge is greatly suppressed. [ABSTRACT FROM AUTHOR]

This communication presents the design of a wideband circularly polarized (CP) antenna array based on sequential rotation (SR) technique that is excited by a substrate integrated coaxial line (SICL) with mature and stable processing technology for millimeter-wave (mm-wave) applications. Initially, the influence of the amplitude and phase errors of the feeding network on the axial ratio of the CP array is analyzed, and the detailed design scheme of the wideband CP array based on SR technology is summarized, which can be used to design SR CP array with wide bandwidth and high polarization purity. Then, an SICL-fed $4 \times 4$ CP array working in the mm-wave band that is composed of two substrate layers and a bonding film layer is designed. The radiation element is processed with a larger chamfering, which can realize elliptically polarized radiation in a broadband range, and the impedance bandwidth is significantly expanded relative to the working state of linearly polarized and CP, which has a significant impact on the final array working bandwidth enhancement. The feeding network and radiation elements are directly connected in the same plane. Finally, the proposed antenna is processed and measured to verify the theory and design scheme in this communication. Over the frequency range of 25.0–34.0 GHz, the measured 1.5 dB axial ratio bandwidth of the fabricated prototype is 30.5%, and the return losses are less than −10 dB. The maximum measured peak gain is 16.5 dBi. [ABSTRACT FROM AUTHOR]

A wideband traveling-wave circularly polarized (CP) antenna printed on a single-layer PCB for millimeter-wave (MM-Wave) applications is presented in this communication. The proposed antenna radiates the CP wave on the basis of the principle similar to the classical endfire-mode helical antenna. The proposed antenna is terminated with an absorber to realize traveling-wave radiation. The traveling-wave working mechanism causes the proposed antenna to have a frequency scanning function and higher stability compared with resonant antennas. Curved microstrip transmission lines are adopted as the CP radiation elements; the whole array antenna is etched on a single-layer substrate. A prototype operating at 30 GHz is fabricated and measured. The radiation beam of the proposed antenna scans from − 14.5° (28 GHz) to +22.5° (34 GHz), the axial ratios are lower than 3 dB, and the measured gains show a maximum value of 21.9 dBi at 33 GHz and a minimum value of 20.3 dBi at 28 GHz. The measured $| \text {S}_{11} |$ and $| \text {S}_{21} |$ are lower than −10 and −16 dB, respectively, in the frequencies mentioned above. [ABSTRACT FROM AUTHOR]

This communication presents a dual-polarized series-fed array antenna with 30° beam-pointing for millimeter-wave (MM-Wave) applications. The 45° and −45° polarized subarrays share the aperture in an interdigital shape. The spacing between subarrays with the same polarization orientation is set to $0.56\lambda _{0}$ through the use of narrower T-type folded substrate integrated waveguide (TFSIW) instead of substrate integrated waveguide (SIW). The substrate integrated coaxial line (SICL) is adopted to design the array feeding network. To validate the proposed design, a $4 \times 6$ (single polarization) dual-polarized array antenna operating at 28 GHz with 30° beam-pointing is fabricated. Based on the measurement, the return losses are lower than −10 dB from 27.5 to 28.5 GHz, the isolations between the two polarization ports are higher than 30.0 dB in the frequencies mentioned above, the maximum gain at the center frequency is 15.7 dBi, and the cross-polarization levels are lower than −18.5 dB. The proposed antenna only needs one-step processing with the standard PCB technology without additional stitching assembly. Simulated and measured results of the proposed antennas were compared. [ABSTRACT FROM AUTHOR]

Low-temperature Cu–Cu bonding utilizing pillar and concave on silicon substrate with and without polymer layer is successfully implemented at 200 °C under atmospheric pressure. Finite-element method (FEM) simulations on stress and deformation generated during bonding process are also presented in order to discuss their influence on bonding result of several pillar diameters and of concave sidewall angles originating from the manufacturing process. The alteration of parameters in FEM simulations would also be investigated to enhance the bonding outcome. The parameters include the diameter of pillar, the sidewall angle of concave, the shape of the concave opening, the addition of extra polymer layer under Cu concave layer, the bonding temperature, and the pitch of the pillar–concave structure. The implementation of Cu–Cu bonding using pillar–concave structure could have a prospective effect on existing packaging methods in semiconductor industry with benefits of applicability to various sorts of substrates and low bonding temperature. [ABSTRACT FROM PUBLISHER]

The performance of GaN-based flip-chip light-emitting diodes (LEDs) with embedded air voids grown on a selective-area Ar-implanted sapphire (SAS) substrate was demonstrated in this letter. The GaN-based epitaxial layers grown on Ar-implanted regions exhibited lower growth rates compared with those grown on implantation-free regions. Accordingly, air voids formed over the implanted regions after merging laterally grown GaN facet fronts. The light-output power of LEDs grown on SAS was greater than that of LEDs grown on implantation-free sapphire substrates. The output power of LEDs grown on SAS was enhanced by 20% at an injection current of 700 mA. The increase in output power was mainly attributed to the scattering of light around the air voids, which increased the probability of photons escaping from the LEDs. [ABSTRACT FROM PUBLISHER]