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This paper presents a highly efficient class-F rectifier based on a harmonic-controlled voltage doubler (HCVD) structure. Previous studies on voltage doubler-based class-F rectifiers, have primarily configured the harmonic termination network only at the RF input port and the DC output port. In this design, the proposed HCVD comprises a voltage doubler and T-shaped harmonic control network (HCN) connected to each diode of the voltage doubler. The T-shaped HCN can independently manipulate the 2nd and 3rd harmonics of the voltage and current across each diode, thus achieving high efficiency even at low input power compared to the input power with maximum efficiency. Since it can also move the input impedance of the HCVD to the load impedance by adjusting the widths of the three transmission lines without additional matching network, the proposed rectifier can achieve high efficiency across a wide input power and frequency range. The proposed rectifier was implemented with a size of 34.7 mm × 29.7 mm. The measurement results also show that it achieves a peak power conversion efficiency (PCE) of 79 % at 27.2 dBm of input power at 2.45 GHz. The measured PCE was maintained over 50% within an input power range of 6.9–30.0 dBm at 2.45 GHz and a frequency range of 1.55–2.75 GHz at 27 dBm of input power.

Abstract Transcription coupled-nucleotide excision repair (TC-NER) removes DNA lesions that block RNA polymerase II (Pol II) transcription. A key step in TC-NER is the recruitment of the TFIIH complex, which initiates DNA unwinding and damage verification; however, the mechanism by which TFIIH is recruited during TC-NER, particularly in yeast, remains unclear. Here, we show that the C-terminal domain (CTD) of elongation factor-1 (Elf1) plays a critical role in TC-NER in yeast by binding TFIIH. Analysis of genome-wide repair of UV-induced cyclobutane pyrimidine dimers (CPDs) using CPD-seq indicates that the Elf1 CTD in yeast is required for efficient TC-NER. We show that the Elf1 CTD binds to the pleckstrin homology (PH) domain of the p62 subunit of TFIIH in vitro, and identify a putative TFIIH-interaction region (TIR) in the Elf1 CTD that is important for PH binding and TC-NER. The Elf1 TIR shows functional, structural, and sequence similarities to a conserved TIR in the mammalian UV sensitivity syndrome A (UVSSA) protein, which recruits TFIIH during TC-NER in mammalian cells. These findings suggest that the Elf1 CTD acts as a functional counterpart to mammalian UVSSA in TC-NER by recruiting TFIIH in response to Pol II stalling at DNA lesions.

Abstract Structural biology efforts using cryogenic electron microscopy are frequently stifled by specimens adopting “preferred orientations” on grids, leading to anisotropic map resolution and impeding structure determination. Tilting the specimen stage during data collection is a generalizable solution but has historically led to substantial resolution attenuation. Here, we develop updated data collection and image processing workflows and demonstrate, using multiple specimens, that resolution attenuation is negligible or significantly reduced across tilt angles. Reconstructions with and without the stage tilted as high as 60° are virtually indistinguishable. These strategies allowed the reconstruction to 3 Å resolution of a bacterial RNA polymerase with preferred orientation, containing an unnatural nucleotide for studying novel base pair recognition. Furthermore, we present a quantitative framework that allows cryo-EM practitioners to define an optimal tilt angle during data acquisition. These results reinforce the utility of employing stage tilt for data collection and provide quantitative metrics to obtain isotropic maps.

This paper presents a $3^{rd}$ -order intermodulation transponder designed to achieve high suppression of fundamental two-tone signals simultaneously. In previous papers, a nonlinear response system combining matching and suppression has never been considered. The core innovation lies in the proposed output matching network, which effectively shifts the output impedance of the diode to the load impedance at the target intermodulation frequency of 2.3 GHz and to short at the fundamental frequencies of 2.4 and 2.5 GHz. It achieves a high conversion gain and provides a substantial isolation between a two-tone fundamental input port and an intermodulation output port through a sharp band-pass filtering characteristic. For validation, we fabricate and measure the proposed intermodulation transponder with dimensions of $72.5\times53$ mm2. The measurement results demonstrate a peak conversion gain of −26 dB at an input power of 8 dBm and an intermodulation frequency of 2.3 GHz. Furthermore, the proposed transponder exhibits suppression characteristics of at least −7 and −23 dBc for the two-tone signals at 2.4 and 2.5 GHz, respectively. A conversion gain of over −30 dB is maintained across an input power range of 3–19 dBm at 2.3 GHz.

In this study, a highly efficient harmonic suppressed dual-band power amplifier (PA) for harmonic radar systems is proposed. The proposed PA incorporates a harmonic-controlled dual-band matching network (HCDMN) comprising $\lambda $ /4 open stubs at the second-harmonic frequencies and series transmission lines. The HCDMN can effectively suppress unwanted second-harmonic signals and control the fundamental and second harmonic impedances to operate in continuous class-F1 mode at two operating frequencies. The implemented PA has dimensions of 75.3 mm $\times 54.9$ mm. Measurement results demonstrate that the PA achieves an exceptional performance, with peak drain efficiencies (DEs) of 81.5 and 71.8 %, saturated output powers of 40.3 and 41.9 dBm, and second harmonic levels of −75.6 and −49.4 dBc at 2.3 and 3.35 GHz, respectively. Furthermore, the DEs remain above 65 % in the two frequency bands of 2.2–2.5 and 3.3–3.45 GHz.

This study introduces a highly efficient harmonic reflection (HR) rectenna designed for precise wireless power transfer (WPT) antenna alignment. The proposed HR rectenna not only converts RF signals to DC power but also transmits a second-harmonic signal to determine the beam alignment between the device and transmitter in diverse environments, including free space and within a medium such as the human body. The proposed rectenna integrates a dual-band slot patch antenna and a HR rectifier. The HR rectifier is configured using a matched voltage doubler and independent second-harmonic impedance control network (ISHICN). To reduce the complexity of the dual-band matching network and mitigate the coupling between the fundamental and harmonic impedances of the HR rectifier, an independent matching technique is applied to a matched voltage doubler and ISHICN, to ensure matching at both the fundamental and harmonic frequencies. Measurement results of the proposed HR rectifier demonstrate impressive performance metrics, including a peak power conversion efficiency (PCE) of 71.6 % at 28 dBm of input power, as well as a peak conversion gain (CG) of -10.4 dB at 8.4 dBm of input power. Notably, the frequency range for PCE >50 % and CG $\gt -22$ dB spans over 0.8 GHz. The antenna adopts a microstrip-fed slot patch design for wide beamwidth at 2.45 GHz and 4.9 GHz, achieving peak gains of 4.9 dBi and 3.8 dBi, respectively. The HR rectenna is integrated with a dual-band microstrip-fed slot patch antenna with sized 60 mm $\times 72.5$ mm. The implemented rectenna is verified to be an efficient WPT receiver through an antenna beam alignment experiment in free space and minced-pork environment.

Abstract Artificially Expanded Genetic Information Systems (AEGIS) add independently replicable unnatural nucleotide pairs to the natural G:C and A:T/U pairs found in native DNA, joining the unnatural pairs through alternative modes of hydrogen bonding. Whether and how AEGIS pairs are recognized and processed by multi-subunit cellular RNA polymerases (RNAPs) remains unknown. Here, we show that E. coli RNAP selectively recognizes unnatural nucleobases in a six-letter expanded genetic system. High-resolution cryo-EM structures of three RNAP elongation complexes containing template-substrate UBPs reveal the shared principles behind the recognition of AEGIS and natural base pairs. In these structures, RNAPs are captured in an active state, poised to perform the chemistry step. At this point, the unnatural base pair adopts a Watson-Crick geometry, and the trigger loop is folded into an active conformation, indicating that the mechanistic principles underlying recognition and incorporation of natural base pairs also apply to AEGIS unnatural base pairs. These data validate the design philosophy of AEGIS unnatural basepairs. Further, we provide structural evidence supporting a long-standing hypothesis that pair mismatch during transcription occurs via tautomerization. Together, our work highlights the importance of Watson-Crick complementarity underlying the design principles of AEGIS base pair recognition.

This study presents a compact reflection-type harmonic transponder with a wide input power range for battery-less radio-frequency identification (RFID) sensors based on harmonic backscattering. Miniaturizing the circuit size of conventional harmonic transponders is difficult because the input and output matching stages are configured separately, and two antennas are used for each port. The proposed harmonic transponder based on a dual-band matching network matches the load simultaneously at the fundamental and second harmonic frequencies over a wide input power range, thus enhancing the conversion gain (CG) with a compact size. For verification, the proposed transponder is implemented in a compact size with dimensions of 19 mm × 17.8 mm. The measured CG of the implemented transponder is maintained at over −10 dB in the wide input power range of −6.4 to 10.6 dBm at 2.45 GHz. The harmonic transponder is configured with a dual-band chip antenna and measured in free space to verify whether it is suitable for battery-less RFID sensors. The measured detectable effective distance to the proposed circuit is 6.3 m in free space, with an equivalent isotropically radiated power of 42.6 dBm.

T7 RNA polymerase (RNAP) is widely used for synthesizing RNA molecules with synthetic modifications and unnatural base pairs (UBPs). Here, authors show the structural basis of how UBPs are recognized as template and substrate, providing mechanistic insights into UBP transcription by T7 RNAP.

This paper presents the design and demonstration of a novel harmonic transponder sensor (HTS) that can measure the position and motion of a target in noisy and reflective indoor environments. In conventional HTS implementation, an impedance mismatch at the input or output can occur because of the impedance variation of the input or output antenna caused by the sensor location or surrounding environment. The impedance mismatch of the input (or output) also affects the output (or input), thereby degrading the conversion gain (CG) of the HTS. An independent impedance control matching network (IICMN) is proposed to deal with the input and output impedances of the HTS separately, regardless of source and load impedance changes. The proposed HTS with an IICMN has a high CG with wide input power and frequency ranges. The proposed HTS was implemented with a size of 44.3-mm $\times29.4$ -mm, and an experiment was conducted to demonstrate its CG. It achieved a peak CG of −14.3-dB at 3.1-GHz. The measured CG remained above −20-dB within a power range of −25-5-dBm at 3.1-GHz and a frequency range of 3.05–3.2-GHz at an input power of −13.7-dBm. The nonlinear responses of the HTS with the dual-band antenna were observed based on the distance and output power. The measurement results showed that the second harmonic signal could be detected at a distance of 2.3-m with an equivalent isotropic radiated power of 31-dBm. The feasibility of the antenna-integrated HTS in estimating spinal cord and nerve injuries was demonstrated using a knee-jerk reflex test. When the distance between the transmitter’s antenna and the antenna-integrated HTS was 0.5-m and the transmitted effective isotopically radiated power was 28.8-dBm, and a received power variation from −80.8 to −59.7-dBm was observed according to the leg movement.

Here the authors provide models of RNA polymerase II bound to the yeast CSB ortholog Rad26 in different nucleotide states; explain how Rad26 domain motions help the polymerase progress past DNA lesions; and interpret the effects of CSB-associated disease mutations.