Browse Articles

A physicochemical rationale for the varied catalytic efficiency in RNase J paralogues

Anomalous shot noise in a bad metal β-tantalum

We investigate the electronic shot noise produced by nanowires of β-Ta, an archetypal “bad” metal with resistivity near the Ioffe–Regel localization limit. The Fano factor characterizing the shot noise exhibits a strong dependence on temperature and is suppressed compared to the expectations for quasiparticle diffusion, but hopping transport is ruled out by the analysis of scaling with the nanowire length. These anomalous behaviors closely resemble those of strange metal nanowires, suggesting that β-Ta may host a correlated electron liquid. This material provides an accessible platform for exploring exotic electronic states of matter.

Protein kinase a suppresses antiproliferative effect of interferon-α in hepatocellular carcinoma by activation of protein tyrosine phosphatase SHP2

Complementary logic-in-memory inverters integrating n-channel and p-channel ferroelectric organic transistors

The emerging logic-in-memory (LIM) technology is a promising strategy to overcome the von Neumann bottleneck in modern computers. For LIM circuits, the complementary structure is desirable for low-power consumption. To date, there have been rare reports on the n-channel organic thin-film transistor nonvolatile memories (OTFT-NVMs), which is indispensable for building the complementary LIM circuits. In this Letter, we demonstrate a route to achieve the low-voltage operatable n-channel OTFT-NVMs, by blade-coating an ultrathin tetratetracontane buffer layer on the oxygen plasma treated ferroelectric terpolymer insulator with a low coercive field. The n-channel OTFT-NVMs exhibit good performances, with a high electron mobility over 0.1 cm2/V s, highly reliable endurance over 1000 cycles, and highly stable retention over 10 000 s. The mechanism for improving device performances is discussed. Moreover, the mechanism and the route for improving performances are also suitable for p-channel OTFT-NVMs. Furthermore, the LIM architecture-based complementary organic inverters are constructed by integrating the n-channel and p-channel OTFT-NVMs, which can well perform logic and memory operations at the low voltage of 10 V. The work laid the foundation for the development of the LIM circuits.

Differences in structure, dynamics, and zinc coordination between isoforms of human ubiquitin ligase UBE3A

A deep convolutional neural network for diffuse correlation tomography

Near-infrared diffuse correlation tomography (DCT) is an emerging technology for tomographic imaging of blood flow index (BFI) in biological tissues through quantifying the light electric field temporal autocorrelation function. With the conventional approaches, proper reconstruction of BFI images is a challenging task from the limited DCT signals due to the severe imbalance between the optical measurements and the voxels to be reconstructed. In this study, we proposed a complete deep learning solution for DCT, including a dataset containing massive prior information for network training, a long short-term memory neural network for DCT signal denoising, as well as a deep convolutional neural network for mapping the DCT signals into the tomographic BFI images. The proposed deep learning solution was comprehensively validated through both computer simulations and phantom experiments, demonstrating its strong superiority over the conventional approach for precise and robustness reconstructions of the target BFI anomalies, with much better performance in reducing errors (i.e., the mean absolute error was reduced by 26.1 times) and preserving fine structure (i.e., the structure similarity index measure was increased by 12.8 times). The proper establishment of a deep learning strategy enables future exploration of the microvasculature blood flow mechanism on pathological tissues even from the limited DCT signals.

The NADH-dependent flavin reductase ThdF follows an ordered sequential mechanism though crystal structures reveal two FAD molecules in the active site

Enhanced thermoelectric performance in AgSbTe2 with extremely low thermal conductivity via grain boundary defects

A delicate balance between high electrical conductivity and ultra-low glass-like thermal conductivity is critical for enhancing thermoelectric performance. Here, by introducing grain boundary trapping states into the AgSbTe2 matrix, the thermally activated release of carriers at elevated temperatures enhances electrical conductivity, while the increased barrier potential induces an energy filtering effect that sustains a high Seebeck coefficient. This synergistic optimization of electrical conductivity and Seebeck coefficient significantly enhances the power factor. Additionally, numerous point defects and a higher density of grain boundaries further enhance phonon scattering, resulting in a 33% reduction in glass-like thermal conductivity compared to the pristine sample. With enhanced power factor and reduced lattice thermal conductivity, Fe-doped AgSbTe2 achieves a remarkable peak zT of 1.8 at 623 K and an impressive zTavg of 1.4 over the temperature range of 323–623 K, showcasing its leading performance in the field. By selecting proper contact layer materials with matched thermal expansion coefficients, low interfacial resistivity was achieved, enabling a single-leg thermoelectric device with ∼10% efficiency under a 323 K temperature difference.

Lipid droplet targeting of the lipase coactivator ABHD5 and the fatty liver disease-causing variant PNPLA3 I148M is required to promote liver steatosis

Improved spectral filtering of broadband diffractive neural network by loss function engineering

We engineer the loss function by removing the conventional physics-based energy constraint during the training of broadband diffractive neural networks (DNNs) to enhance their spectral filtering capabilities of supercontinuum light. Simulations show that compared to DNNs trained with conventional loss function, the suppression of out-of-band spectral intensities can be improved by three orders of magnitude, resulting in an extinction coefficient of 10−6. Additionally, the spectral resolution can be enhanced by over 50% with a 6.6% improvement of energy efficiency. These findings are corroborated by experiments conducted with a two-layer DNN. The proposed method holds promise for enhancing the performance of broadband DNNs across various applications, including spectral reconstruction, spectrum classification, and color image processing, among others.

A leucine responsive small RNA AbcR200 regulates expression of the lactate utilization (lut) operon in Acinetobacter baumannii DS002

Electric field-induced depolarization of direct current and alternating current poled PMN-PT single crystals

Understanding the depolarization of ferroelectric materials caused by external stimuli is critical for maintaining the aligned polarization states. Although thermal depolarization in poled materials is well established, the mechanisms of electric field-induced depolarization remain largely unexplored. In this study, we investigate the electrical depoling behavior of [001]-oriented rhombohedral Pb(Mg1/3Nb2/3)O3-PbTiO3 (PMN-PT) single crystals poled using direct current poling (DCP) and alternating current poling (ACP). We reveal that the ACP sample exhibits a lower reverse coercive field than the DCP specimen. We compare the effects of bipolar and unipolar electric fields applied in the reverse poling direction, analyzing the changes in permittivity and piezoelectric resonance. Piezoresponse force microscopy is employed to characterize domain configurations in poled and electrically depoled samples. Our findings suggest that property degradation may arise from the nucleation and growth of domains oriented opposite to the initial arrangement.

A fucose-binding superlectin from Enterobacter cloacae with high Lewis and ABO blood group antigen specificity

Toward flexible intensity control of resonantly scattered <b> <i>γ</i> </b>-rays using multi-frequency vibrating resonant absorber

We report a method for coherent control of γ-photons, enabling the shaping of γ-ray intensity in nearly arbitrary waveforms. Different intensity waveforms are created by adjusting the motion profile of a resonant absorber (an ensemble of Mössbauer nuclei) and tuning the energy of the incident radiation. A crucial aspect of this method is the use of a low fundamental frequency of vibrations, which broadens the possibilities for γ-ray control. The results of numerical simulations are experimentally validated by generating single and double γ-pulses and inducing short-term absorption. For this, a resonant absorber containing 57Fe nuclei was vibrated with different motion profiles composed of 12 harmonics with a fundamental frequency of 1 MHz. The proposed technique represents an advancement in the manipulation of γ-rays, and potentially x rays, paving the way for the performance of unique types of γ-ray or x-ray quantum experiments and the development of tools such as adjustable table-top γ-pulse sources or γ-ray or x-ray delays and gates. Moreover, inverse application of the method enables investigation of motion at the picometer scale.

ECM stiffness regulates lung fibroblast survival through RasGRF1-dependent signaling

Effect of electronic state for in-materio physical reservoir computing performance with a porphyrin-polyoxometalate/single-walled carbon nanotube network

Semiconducting single-walled carbon nanotube (SWNT)/porphyrin-polyoxometalate (por-POM) networks were fabricated using [H4tBuTPP]2[SV2W10O40] (tBu H4TPP-POM) and [H4TPP]2[SV2W10O40] (H4TPP-POM) to compare their reservoir computing (RC) performances. Nonlinear electrical properties, phase shifts, and higher harmonics, which are required for superior RC performances, were generated in SWNT/por-POM networks. Lissajous plots show various phase shifts as the input frequency decreases, reflecting the relaxation time of the dynamics in the por-POMs. The SWNT/H4TPP-POM network exhibits the best performance of the RC benchmark task, indicating that H4TPP-POM generates rich chemical dynamics based on different charge accumulation with different electronic state in por-POM.

The “Ins and Outs and What-Abouts” of H2A.Z: A tribute to C. David Allis

One-step fabrication of sharp platinum/iridium tips via amplitude-modulated alternating-current electropolishing

The platinum/iridium (Pt/Ir) alloy tip for scanning probe microscopy was fabricated by amplitude-modulated alternating-current electropolishing. The clean tips with a radius of curvature less than 100 nm were reproducibly obtained by applying the sinusoidal voltage in the frequency (f0) of 900 Hz≤f0≤1500 Hz with amplitude modulation by the sinusoidal wave in the modulation frequency (fs) of fs=0.1f0 in CaCl2/H2O/acetone solution. The analyses by scanning electron microscopy with an energy-dispersive x-ray analyzer and atom probe tomography showed that a uniform Pt/Ir alloy was exposed on the tip surface as a clean surface without O or Cl contamination. The scanning tunneling microscopy (STM) imaging using the fabricated tip showed that it is more suitable for investigating rough surfaces than conventional as-cut tips and applicable for atomic-resolution imaging. Furthermore, we applied the fabricated tip to qPlus atomic force microscopy (AFM) analysis in liquid and showed that it has atomic resolution in both the horizontal and vertical directions. Therefore, it is concluded that the amplitude-modulated AC etching method reproducibly provides sharp STM/AFM tips capable of both atomic resolution and large-area analyses without complex etching setups.

Evolutionary scenarios for the specific recognition of nonhomologous endogenous peptides by G protein–coupled receptor paralogs

Signal-noise analysis of miniaturized delta-E effect magnetic field sensors

Delta-E effect sensors developed for detecting small amplitude and low-frequency magnetic fields have shown potential for miniaturization. However, a comprehensive signal-and-noise analysis of such miniaturized sensors is lacking. Here, we present an in-depth study of the key performance characteristics of sub-millimeter-sized delta-E effect sensors with a double-wing resonator geometry. Several resonance modes are evaluated for their sensitivity, noise, and limit of detection (LoD) as functions of the excitation voltage amplitude and magnetic bias flux density. We identify and discuss the optimal conditions for sensor operation and compare the performance to that of the reported macroscopic devices. While all investigated resonance modes behave qualitatively similar, quantitative differences in signal and noise lead to an almost sevenfold difference in LoD s. The performance is limited by magnetic noise at large excitation amplitudes and, unlike reported macroscopic delta-E effect sensors, by noise from the excitation signal and charge amplifier at low excitation amplitudes. The best performance is achieved in the third resonance mode excited at 683 kHz with a LoD≤7.4±3 nT/Hz between 10 and 1000 Hz and a minimum of 2.8 nT/Hz at 195 Hz. This demonstrates an improvement over previously reported values for miniaturized delta-E effect sensors in this frequency range. Moreover, the sensors show a −3 dB bandwidth of ≈440 Hz, which is significantly wider compared to macroscopic delta-E effect sensors. Reducing electronic noise and employing advanced magnetic multilayers can further improve the LoD, making these miniaturized sensors promising candidates for compact arrays.