Reinforcement learning-trained optimisers and Bayesian optimisation for online particle accelerator tuning.

Online tuning of particle accelerators is a complex optimisation problem that continues to require manual intervention by experienced human operators. Autonomous tuning is a rapidly expanding field of research, where learning-based methods like Bayesian optimisation (BO) hold great promise in improving plant performance and reducing tuning times. At the same time, reinforcement learning (RL) is a capable method of learning intelligent controllers, and recent work shows that RL can also be used to train domain-specialised optimisers in so-called reinforcement learning-trained optimisation (RLO). In parallel efforts, both algorithms have found successful adoption in particle accelerator tuning. Here we present a comparative case study, assessing the performance of both algorithms while providing a nuanced analysis of the merits and the practical challenges involved in deploying them to real-world facilities. Our results will help practitioners choose a suitable learning-based tuning algorithm for their tuning tasks, accelerating the adoption of autonomous tuning algorithms, ultimately improving the availability of particle accelerators and pushing their operational limits.

Self-Assembled Interlayer Enables High-Performance Organic Photovoltaics with Power Conversion Efficiency Exceeding 20.

Interfacial layers (ILs) are prerequisites to form the selective charge transport for high-performance organic photovoltaics (OPVs) but mostly result in considerable parasitic absorption loss. Trimming the ILs down to a mono-molecular level via the self-assembled monolayer is an effective strategy to mitigate parasitic absorption loss. However, such a strategy suffers from inferior electrical contact with low surface coverage on rough surfaces and poor producibility. To address these issues, here, the self-assembled interlayer (SAI) strategy is developed, which involves a thin layer of 2-6 nm to form a full coverage on the substrate via both covalent and van der Waals bonds by using a self-assembled molecule of 2-(9H-carbazol-9-yl) (2PACz). Via the facile spin coating without further rinsing and annealing process, it not only optimizes the electrical and optical properties of OPVs, which enables a world-record efficiency of 20.17% (19.79% certified) but also simplifies the tedious processing procedure. Moreover, the SAI strategy is especially useful in improving the absorbing selectivity for semi-transparent OPVs, which enables a record light utilization efficiency of 5.34%. This work provides an effective strategy of SAI to optimize the optical and electrical properties of OPVs for high-performance and solar window applications.

What is cooking in your kitchen: seeing "invisible" with time-resolved coherent anti-Stokes Raman spectroscopy.

Cooking oil is a critical component of human food and its main component, lipid, is influential to health, but assessing its authenticity and quality can be challenging due to its complex chemical composition. In this study, we introduce a novel application of time-resolved coherent anti-Stokes Raman scattering (T-CARS) spectroscopy for detecting adulteration and understanding the mechanisms of lipid oxidation in various cooking oils. Our research surpasses the limitations of conventional spontaneous Raman spectroscopy, demonstrating that intra-molecular interactions from unsaturated bonds in triglycerides significantly influence vibrational dephasing time. We observed that these dephasing times, although diverse initially, converge to a similar value after heating cycles. Notably, a longer vibrational dephasing of the CH2 symmetric stretching mode was found to correlate with a higher lipid oxidation rate. These findings underscore the potential of T-CARS in identifying and characterizing subtle molecular interactions, offering a transformative approach to understanding molecular dynamics. This research paves the way for broader applications of T-CARS across fields such as chemistry, biomedicine, and material science, marking a significant advancement in the development of innovative analytical techniques.

Quantum Induced Coherence Light Detection and Ranging.

Quantum illumination has been proposed and demonstrated to improve the signal-to-noise ratio (SNR) in light detection and ranging (LiDAR). When relying on coincidence detection alone, such a quantum LiDAR is limited by the timing jitter of the detector and suffers from jamming noise. Inspired by the Zou-Wang-Mandel experiment, we design, construct, and validate a quantum induced coherence (QuIC) LiDAR which is inherently immune to ambient and jamming noises. In traditional LiDAR the direct detection of the reflected probe photons suffers from deteriorating SNR for increasing background noise. In QuIC LiDAR we circumvent this obstacle by only detecting the entangled reference photons, whose single-photon interference fringes are used to obtain the distance of the object, while the reflected probe photons are used to erase path information of the reference photons. In consequence, the noise accompanying the reflected probe light has no effect on the detected signal. We demonstrate such noise resilience with both LED and laser light to mimic the background and jamming noise. The proposed method paves a new way of battling noise in precise quantum electromagnetic sensing and ranging.

Improving the profile and reliability of cytoplasmic proteins from M. tuberculosis using biomimetic affinity chromatography coupled with LC-MS/MS analysis.

M. tuberculosis is the most successful intracellular pathogen and remains a major threat to human health. It is crucial to investigate the profile of cytoplasmic proteins from M. tuberculosis for pathogenesis, clinical markers, and protein vaccine development. In this study, six biomimetic affinity chromatography (BiAC) resins with high differences were selected for M. tuberculosis-cytoplasmic protein fractionation. All fractions were identified using liquid chromatography-mass spectrometry (LC-MS/MS) analysis. A total of 1246 M. tuberculosis proteins were detected (p < 0.05), among which 1092 M. tuberculosis proteins were identified in BiAC fractionations and 714 M. tuberculosis proteins in un-fractionations (Table S1.3.1). The majority of 66.8% (831/1246) identifications were distributed in the range of Mw 7.0-70.0 kDa, pI 3.5-8.0, and Gravy values <0.3. Furthermore, 560 M. tuberculosis proteins were detected in both the BiAC fractionations and un-fractionations. Compared with the un-fractionations, the average number of prot_matches, prot_cover, prot_sequence, and emPAI values of these 560 proteins in the BiAC fractionations were increased by 3.791, 1.420, 1.307, and 1.788 times, respectively. Overall, compared with un-fractionations, the confidence and profile of M. tuberculosis cytoplasmic proteins were improved by BiAC fractionations coupled with LC-MS/MS analysis. The strategy of BiAC fractionation can be used as an effective method for pre-separating protein mixtures in proteomic studies.

Measuring Zak phase in room-temperature atoms.

Cold atoms provide a flexible platform for synthesizing and characterizing topological matter, where geometric phases play a central role. However, cold atoms are intrinsically prone to thermal noise, which can overwhelm the topological response and hamper promised applications. On the other hand, geometric phases also determine the energy spectra of particles subjected to a static force, based on the polarization relation between Wannier-Stark ladders and geometric Zak phases. By exploiting this relation, we develop a method to extract geometric phases from energy spectra of room-temperature superradiance lattices, which are momentum-space lattices of timed Dicke states. In such momentum-space lattices the thermal motion of atoms, instead of being a source of noise, provides effective forces which lead to spectroscopic signatures of the Zak phases. We measure Zak phases directly from the anti-crossings between Wannier-Stark ladders in the Doppler-broadened absorption spectra of superradiance lattices. Our approach paves the way of measuring topological invariants and developing their applications in room-temperature atoms.

Enhanced Chemical Sensing with Multiorder Coherent Raman Scattering Spectroscopic Dephasing.

Molecular vibrational spectroscopy is widely used in various sensing and imaging applications, providing intrinsic information at the molecular level. Nonlinear optical interactions using ultrashort laser pulses facilitate the selective coherent excitation of molecular vibrational modes by focusing energy into specific molecular bonds, boosting the signal level for multiple orders of magnitude. The dephasing of such coherence, which is susceptible to the local molecular environment, however, is often neglected. The unique capability of vibrational dephasing dynamics to serve as a unique probe for complex molecular interactions and the effect of local nano- and microenvironments are beyond the reach of conventional, intensity-based spectroscopy. Here, we developed a novel multiorder coherent Raman spectroscopy platform with a special focus on the temporal evolution of molecular vibrational dephasing, termed as time-resolved coherent Raman scattering (T-CRS) spectroscopy. By utilizing a high dynamic range detection, molecular vibrational dynamics and the environmental effects are demonstrated with multidimensional spectroscopic sensing, which promises a new range of applications in biology, materials, and chemical sciences.

Targeting effect of berberine on type I fimbriae of Salmonella Typhimurium and its effective inhibition of biofilm.

As a primary cause of food contamination and human diseases, Salmonella Typhimurium can easily form a biofilm that is difficult to remove from food surfaces, and often causes significant invisible threats to food safety. Although berberine has been widely used as an anti-infective drug in traditional medicine, some basic principles underlying its mechanism, especially the interaction between berberine and type I fimbriae genes, has not been verified yet. In this study, two strains of major fimbrial gene mutants (ΔfimA and ΔfimH) were constructed to demonstrate the possible action of berberine on type I fimbriae genes. The broth microdilution method was used to determine the antibacterial activity of berberine against selected strains (WT, ΔfimA, and ΔfimH). Cell agglutination experiments revealed that the number of S. Typhimurium type I fimbriae reduced after berberine treatment, which was consistent with transmission electron microscopy results. Quantitative real-time PCR experiments also confirmed that berberine reduced fimA gene expression, indicating a certain interaction between berberine and fimA gene. Furthermore, confocal laser scanning microscopy imaging of biofilm clearly revealed that berberine prevents biofilm formation by reducing the number of type I fimbriae. Overall, it is well speculated for us that berberine could be an excellent combating-biofilm drug in clinical microbiology and food preservation. KEY POINTS: • Reduce the number of fimbriae. • Berberine targeting fimA. • Effective biofilm inhibitor.

Flagellar Motility Is Critical for Salmonella enterica Serovar Typhimurium Biofilm Development.

The food-borne pathogen Salmonella enterica serovar Typhimurium (S. Typhimurium) causes self-limiting gastroenteritis in humans and is not easily eradicated because it often attaches to suitable surfaces to form biofilms that have high resistance to disinfectants and antimicrobials. To develop an alternative strategy for the treatment of biofilms, it is necessary to further explore the effects of flagellar motility on the development process of Salmonella biofilms. Here, we constructed flagella mutants (ΔflgE and ΔfliC) to systematically study this process. By comparing them with wild-type strains, we found that these mutants lacking flagellar motility form fewer biofilms in the early stage, and the formed mature biofilms contain more cells and extracellular polymeric substances (EPS). In addition, fewer mutant cells adhered to glass plates compared with wild-type cells even after 6 h of incubation, suggesting that flagellar motility plays a significant role in preliminary cell-surface interactions. More importantly, the motility of wild-type strain was greatly decreased when they were treated with carbonyl cyanide m-chlorophenylhydrazone, which inhibited flagellar motility and reduced biofilm formation, as in the case of the ΔflgE mutant. Overall, these findings suggest that flagellar motility plays an important role in Salmonella biofilm initiation and maturation, which can help us to counteract the mechanisms involved in biofilm formation and to develop more rational control strategies.

Enhanced displacements in reflected beams at hyperbolic metamaterials.

We examine the Goos-Hänchen (G-H) shift of a Gaussian beam reflected on a thin slab of Ag/TiO2 hyperbolic multilayer metamaterial (HMM). The HMM is modeled using the effective medium theory which yields the anisotropic dielectric functions of the HMM. The G-H shifts can be very large on the surface of the HMM. It can be about 40 µm which are far bigger than the G-H shifts on the usual materials like metals and dielectrics. The enhancement is due to the excitation of the Brewster modes in HMM. Such Brewster modes in HMM have a well-defined frequency-dependent line shape. We relate the the half width at half maximum of the G-H shift to the imaginary part of the complex frequency of the Brewster mode. Moreover, we also present results for the Imbert-Fedorov shifts as well as the spin Hall effect of light on the surface of a thin HMM slab. We show that the spin Hall effect on the HMM slab is much more pronounced than that on the surface of metal. Thus a thin HMM slab can be used to enhance the lateral displacements, which can have many interesting applications for optical devices.