10 research outputs found
Acoustic diagnostics of femtosecond laser filamentation
The promising application of femtosecond laser filamentation in atmospheric
remote sensing brings imperative demand for diagnosing the spatiotemporal
dynamics of filamentation. Acoustic emission (AE) during filamentation opens a
door to give the insight into the dynamic evolution of filaments in air. In
particular, the frequency features of the acoustic emission provide relevant
information on the conversion of laser energy to acoustic energy. Here, the
acoustic emission of femtosecond laser filament manipulated by energy and the
focal lengths was measured quantitatively by a broadband microphone, and the
acoustic parameters were compared and analyzed. Our results showed that the
acoustic power presents a squared dependence on the laser energy and the
bandwidth of the acoustic spectrum showed a significant positive correlation
with laser energy deposition. It was found that the spectrum of the acoustic
pulse emitted from the middle of the filament has a larger bandwidth compared
to those emitted from the ends of the filament and the spectrum of the acoustic
pulse is also an indicator of the filament intensity distribution. These
findings are helpful for studying the plasma filament properties and complex
dynamic processes through acoustic parameters and allow the optimization of
remote applications.Comment: 8 pages,5 figure
Femtosecond Laser Filamentation in Atmospheric Turbulence
The effects of turbulence intensity and turbulence region on the distribution
of femtosecond laser filaments are experimentally elaborated. Through the
ultrasonic signals emitted by the filaments, and it is observed that increasing
turbulence intensity and expanding turbulence active region cause an increase
in the start position of the filament, and a decrease in filament length, which
can be well explained by the theoretical calculation. It is also observed that
the random perturbation of the air refractive index caused by atmospheric
turbulence expanded the spot size of the filament. Additionally, when
turbulence intensity reaches , multiple filaments are formed. Furthermore, the
standard deviation of the transverse displacement of filament is found to be
proportional to the square root of turbulent structure constant under the
experimental turbulence parameters in this paper. These results contribute to
the study of femtosecond laser propagation mechanisms in complex atmospheric
turbulence conditionsComment: 9 pages, 4 figure
Coupled air lasing gain and Mie scattering loss: aerosol effect in filament-induced plasma spectroscopy
Femtosecond laser filament-induced plasma spectroscopy (FIPS) demonstrates
great potentials in the remote sensing for identifying atmospheric pollutant
molecules. Due to the widespread aerosols in atmosphere, the remote detection
based on FIPS would be affected from both the excitation and the propagation of
fingerprint fluorescence, which still remain elusive. Here the physical model
of filament-induced aerosol fluorescence is established to reveal the combined
effect of Mie scattering and amplification spontaneous emission, which is then
proved by the experimental results, the dependence of the backward fluorescence
on the interaction length between filament and aerosols. These findings provide
an insight into the complicated aerosol effect in the overall physical process
of FIPS including propagation, excitation and emission, paving the way to its
practical application in atmospheric remote sensing.Comment: 7 pages, 4 figure
High performance TadA-8e derived cytosine and dual base editors with undetectable off-target effects in plants
Abstract Cytosine base editors (CBEs) and adenine base editors (ABEs) enable precise C-to-T and A-to-G edits. Recently, ABE8e, derived from TadA-8e, enhances A-to-G edits in mammalian cells and plants. Interestingly, TadA-8e can also be evolved to confer C-to-T editing. This study compares engineered CBEs derived from TadA-8e in rice and tomato cells, identifying TadCBEa, TadCBEd, and TadCBEd_V106W as efficient CBEs with high purity and a narrow editing window. A dual base editor, TadDE, promotes simultaneous C-to-T and A-to-G editing. Multiplexed base editing with TadCBEa and TadDE is demonstrated in transgenic rice, with no off-target effects detected by whole genome and transcriptome sequencing, indicating high specificity. Finally, two crop engineering applications using TadDE are shown: introducing herbicide resistance alleles in OsALS and creating synonymous mutations in OsSPL14 to resist OsMIR156-mediated degradation. Together, this study presents TadA-8e derived CBEs and a dual base editor as valuable additions to the plant editing toolbox
WDR77 inhibits prion-like aggregation of MAVS to limit antiviral innate immune response
Abstract RIG-I-MAVS signaling pathway plays a crucial role in defending against pathogen infection and maintaining immune balance. Upon detecting viral RNA, RIG-I triggers the formation of prion-like aggregates of the adaptor protein MAVS, which then activates the innate antiviral immune response. However, the mechanisms that regulate the aggregation of MAVS are not yet fully understood. Here, we identified WDR77 as a MAVS-associated protein, which negatively regulates MAVS aggregation. WDR77 binds to MAVS proline-rich region through its WD2-WD3-WD4 domain and inhibits the formation of prion-like filament of recombinant MAVS in vitro. In response to virus infection, WDR77 is recruited to MAVS to prevent the formation of its prion-like aggregates and thus downregulate RIG-I-MAVS signaling in cells. WDR77 deficiency significantly potentiates the induction of antiviral genes upon negative-strand RNA virus infections, and myeloid-specific Wdr77-deficient mice are more resistant to RNA virus infection. Our findings reveal that WDR77 acts as a negative regulator of the RIG-I-MAVS signaling pathway by inhibiting the prion-like aggregation of MAVS to prevent harmful inflammation
Selective and Sensitive Monitoring of Cerebral Antioxidants Based on the Dye-Labeled DNA/Polydopamine Conjugates
A simple
and novel method for evaluating antioxidants in complex
biological fluids has been developed based on the interaction of dye-labeled
single-strand DNA (ssDNA) and polydopamine (PDA). Due to the interaction
between ssDNA and PDA, the fluorescence of dye-labeled ssDNA (e.g.,
FITC-ssDNA, as donor) can be quenched by PDA (as acceptor) to the
fluorescence āoffā state through FoĢrster resonance
energy transfer (FRET). However, in the presence of various antioxidants,
such as glutathione (GSH), ascorbic acid (AA), cysteine (Cys), and
homocysteine (Hcys), the spontaneous oxidative polymerization reaction
from DA to PDA would be blocked, resulting in the freedom of FITC-ssDNA
and leading to the fluorescence āonā state. The sensing
system shows great sensitivity for the monitoring of antioxidants
in a fluorescent āturn onā format. The new strategy
also exhibits great selectivity and is free from the interferences
of amino acids, metal ions and the biological species commonly existing
in brain systems. Moreover, by combining the microdialysis technique,
the present method has been successfully applied to monitor the dynamic
changes of the striatum antioxidants in rat cerebrospinal microdialysates
during the normal/ischemia/reperfusion process. This work establishes
an effective platform for in vivo monitoring antioxidants in cerebral
ischemia model, and promises new opportunities for the research of
brain chemistry, neuroprotection, physiological, and pathological
events
Efficient plant genome engineering using a probiotic sourced CRISPR-Cas9 system
Abstract Among CRISPR-Cas genome editing systems, Streptococcus pyogenes Cas9 (SpCas9), sourced from a human pathogen, is theĀ most widely used. Here, through in silico data mining, we haveĀ established an efficient plant genome engineering system using CRISPR-Cas9 from probiotic Lactobacillus rhamnosus. We haveĀ confirmed the predicted 5ā-NGAAA-3ā PAM via a bacterial PAM depletion assay and showcased its exceptional editing efficiency in rice, wheat, tomato, and Larix cells, surpassing LbCas12a, SpCas9-NG, and SpRY when targeting the identical sequences. In stable rice lines, LrCas9 facilitates multiplexed gene knockout through coding sequence editing and achieves gene knockdown via targeted promoter deletion, demonstrating high specificity. We have also developed LrCas9-derived cytosine and adenine base editors, expanding base editing capabilities. Finally, by harnessing LrCas9ās A/T-rich PAM targeting preference, we haveĀ created efficient CRISPR interference and activation systems in plants. Together, our work establishes CRISPR-LrCas9 as an efficient and user-friendly genome engineering tool for diverse applications in crops and beyond