Auto-focusing femtosecond laser manufacturing system via acoustic emission technology.

Auto-focusing technology in ultrafast laser processing, especially for non-planar structures, holds paramount importance. The existing methodologies predominantly rely on optical mechanisms, thereby being limited by the original system and material reflectivity. This work proposes an approach that utilizes laser-induced sound as a feedback signal for system control, thereby circumventing the need for optical system adjustments and facilitating almost real-time tracking. We established an ultrafast laser processing system augmented by acoustic emission technology, allowing for focus tracking on inclined planes. This system also exhibits the capability to generate diverse microscopic morphologies, including grooves and differently oriented laser-induced periodic surface structures (LIPSS), through the manipulation of the acoustic signal threshold. This method can be easily integrated into existing laser processing systems, offering new capabilities for curved surface processing, microstructure manufacturing, and transparent material processing.

Uncommon optic nerve arteriovenous malformation: A case report and literature review.

BACKGROUND: The rapid progress in imaging techniques has led to an upsurge in the incidence of optic nerve arteriovenous malformations (AVMs) diagnoses. Nevertheless, a comprehensive integration addressing their diagnostic and therapeutic attributes remains elusive. CASE DESCRIPTION AND THE LITERATURE REVIEW: In this report, we present a case of optic nerve AVM in a patient who initially presented with progressive visual deterioration in the right eye. An orbital magnetic resonance imaging (MRI) scan revealed an abnormal signal intensity within the optic nerve region of the affected eye, and Computed Tomography Angiography (CTA) demonstrated the presence of a vascular malformation involving the optic nerve in the right eye. The diagnosis of optic nerve AVMs relies on Digital Subtraction Angiography (DSA). Given the challenging nature of surgical intervention, the patient opted for conservative management. Upon subsequent evaluation, no significant changes were observed in the patient's right visual acuity and visual field. Furthermore, a comprehensive literature review was conducted. CONCLUSIONS: In summary, the principal clinical presentations associated with optic nerve AVMs include a deterioration in both visual acuity and visual field. Angiography serves as the preferred diagnostic modality to confirm optic nerve AVMs. Microsurgical intervention or interventional embolization techniques may offer effective management approaches to address this complex condition.

Accuracy improvement of demodulating the stress field with StressUnet in photoelasticity.

Evaluating the stress field based on photoelasticity is of vital significance in engineering fields. To achieve the goal of efficiently demodulating stress distribution and to overcome the limitations of conventional methods, it is essential to develop a deep learning method to simplify and accelerate the process of image acquisition and processing. A framework is proposed to enhance prediction accuracy. By adopting Resnet as the backbone, applying U-Net architecture, and adding a physical constraint module, our model recovers the stress field with higher structural similarity. Under different conditions, our model performs robustly despite complicated geometry and a large stress range. The results prove the universality and effectiveness of our model and offer an opportunity for instant stress detection.

MXenes: Synthesis, Optical Properties, and Applications in Ultrafast Photonics.

Recently, 2D materials are in great demand for various applications such as optical devices, supercapacitors, sensors, and biomedicine. MXenes as a kind of novel 2D material have attracted considerable research interest due to their outstanding mechanical, thermal, electrical, and optical properties. Especially, the excellent nonlinear optical response enables them to be potential candidates for the applications in ultrafast photonics. Here, a review of MXenes synthesis, optical properties, and applications in ultrafast lasers is presented. First, aqueous acid etching and chemical vapor deposition methods for preparing MXenes are introduced, in which the storage stability and challenges of the existing synthesis techniques are also discussed. Then, the optical properties of MXenes are discussed specifically, including plasmonic properties, optical detection, photothermal effects, and ultrafast dynamics. Furthermore, the typical ultrafast pulsed lasers enabled by MXene-based saturable absorbers operated at different wavelength regions are summarized. Finally, a summary and outlook on the development of MXenes is presented in the perspectives section.

Molecular insights into MXene destructing the cell membrane as a "nano thermal blade".

As a novel two-dimensional material, the most popular MXene (Ti3C2Tx) has presented promising therapeutic effects in cancer and bacterial infections under near infrared light illumination. However, there is still a lack of molecular level insight on the destruction of the cell membrane by MXene. In this work, a series of molecular dynamics simulations were conducted to capture the nanosheet destruction processes. The results showed that the penetration of the MXene nanosheet into the cell membrane is a non-spontaneous process, which required an enormous external force compared to other nanomaterials. Besides, the plasma membrane was disrupted during the penetration process. After the demonstration of disturbing the lipid membrane by higher temperature, we also found that there exists a significantly high effective thermal conduction pathway at the Ti3C2-POPC lipid interface mediated by van der Waals interactions and hydrogen bonds. The findings provide an understanding of the MXene-related cancer therapy and antibacterial activity, and offer guidance for the broader applications of MXene in the field of biomedicine.

Robustness and accuracy improvement of data processing with 2D neural networks for transient absorption dynamics.

To achieve the goal of efficiently analyzing transient absorption spectra without arbitrary assumption and to overcome the limitations of conventional methods in fitting ability and highly noised backgrounds, it is essential to develop new tools to achieve more accurate and robust prediction based on the intrinsic properties of a spectrum even under strong noise. In this work, Lasso regression and neural network were combined to achieve an effective fitting. Compared to the conventional global fitting method, our network could automatically determine the exponential form on each wave unit, in which the accuracy was as high as 97%. Thereafter, the lifetime with the corresponding amplitude ratio could be easily predicted by the neural network on each wave unit. This kind of prediction is difficult to achieve by global fitting due to the limitation of computational resources. Furthermore, more accurate fitting even under weak signals could be achieved for the mean square error (MSE) decreasing by more than 100 times on average compared to conventional global fitting methods. Attributed to its improved accuracy and robustness, our developed algorithm could be readily applied to analyze time-resolved transient spectra.

Forecasting nonadiabatic dynamics using hybrid convolutional neural network/long short-term memory network.

Modeling nonadiabatic dynamics in complex molecular or condensed-phase systems has been challenging, especially for the long-time dynamics. In this work, we propose a time series machine learning scheme based on the hybrid convolutional neural network/long short-term memory (CNN-LSTM) framework for predicting the long-time quantum behavior, given only the short-time dynamics. This scheme takes advantage of both the powerful local feature extraction ability of CNN and the long-term global sequential pattern recognition ability of LSTM. With feature fusion of individually trained CNN-LSTM models for the quantum population and coherence dynamics, the proposed scheme is shown to have high accuracy and robustness in predicting the linearized semiclassical and symmetrical quasiclassical mapping dynamics as well as the mixed quantum-classical Liouville dynamics of various spin-boson models with learning time up to 0.3 ps. Furthermore, if the hybrid network has learned the dynamics of a system, this knowledge is transferable that could significantly enhance the accuracy in predicting the dynamics of a similar system. The hybrid CNN-LSTM network is thus believed to have high predictive power in forecasting the nonadiabatic dynamics in realistic charge and energy transfer processes in photoinduced energy conversion.

Plasmonic Light Illumination Creates a Channel To Achieve Fast Degradation of Ti3C2T x Nanosheets.

Two-dimensional (2D) material-controllable degradation under light radiation is crucial for their photonics and medical-related applications, which are yet to be investigated. In this paper, we first report the laser illumination method to regulate the degradation rate of Ti3C2T x nanosheets in aqueous solution. Comprehensive characterization of intermediates and final products confirmed that plasmonic laser promoting the oxidation was strikingly different from heating the aqueous solution homogeneously. Laser illumination would nearly 10 times accelerate the degradation of Ti3C2T x nanosheets in initial stage and create many smaller-sized oxidized products in a short time. Laser-induced fast degradation was principally ascribed to surface plasmonic resonance effect of Ti3C2T x nanosheets. The degradation ability of such illumination could be controlled either by tuning the excitation wavelength or changing the excitation power. Furthermore, the laser- or thermal-induced degradation could be retarded by surface protection of Ti3C2T x nanosheets. Our results suggest that plasmonic electron excitation of Ti3C2T x nanosheets could build a new reaction channel and lead to the fast oxidation of nanosheets in aqueous solution, potentially enabling a series of water-based applications.

Intermolecular energy flows between surface molecules on metal nanoparticles.

Three model systems are designed to investigate energy transport between molecules on metal nanoparticle surfaces. Energy is rapidly transferred from one carbon monoxide (CO) molecule to another CO molecule or an organic molecule on adjacent surface sites of 2 nm Pt particles within a few picoseconds. On the contrary, energy flow from a surface organic molecule to an adjacent CO molecule is significantly slower and, in fact, within experimental sensitivity and uncertainty the transfer is not observed. The energy transport on particle surfaces (about 2 km s-1) is almost ten times faster than inside a molecule (200 m s-1). The seemingly perplexing observations can be well explained by the combination of electron/vibration and vibration/vibration coupling mechanisms, which mediate molecular energy dynamics on metal nanoparticle surfaces: the strong electron/vibration coupling rapidly converts CO vibrational energy into heat that can be immediately sensed by nearby molecules; but the vibration/vibration coupling dissipates the vibrational excitation in the organic molecule as low-frequency intramolecular vibrations that may or may not couple to surface electronic motions.

Nonresonant energy transfers independent on the phonon densities in polyatomic liquids.

Energy-gap-dependent vibrational-energy transfers among the nitrile stretches of KSCN/KS(13)CN/KS(13)C(15)N in D2O, DMF, and formamide liquid solutions at room temperature were measured by the vibrational-energy-exchange method. The energy transfers are slower with a larger energy donor/acceptor gap, independent of the calculated instantaneous normal mode ("phonons" in liquids) densities or the terahertz absorption spectra. The energy-gap dependences of the nonresonant energy transfers cannot be described by phonon compensation mechanisms with the assumption that phonons are the instantaneous normal modes of the liquids. Instead, the experimental energy-gap dependences can be quantitatively reproduced by the dephasing mechanism. A simple theoretical derivation shows that the fast molecular motions in liquids randomize the modulations on the energy donor and acceptor by phonons and diminish the phonon compensation efficiency on energy transfer. Estimations based on the theoretical derivations suggest that, for most nonresonant intermolecular vibrational-energy transfers in liquids with energy gaps smaller than the thermal energy, the dephasing mechanism dominates the energy-transfer process.

Molecular distances determined with resonant vibrational energy transfers.

In general, intermolecular distances in condensed phases at the angstrom scale are difficult to measure. We were able to do so by using the vibrational energy transfer method, an ultrafast vibrational analogue of Förster resonance energy transfer. The distances among SCN(-) anions in KSCN crystals and ion clusters of KSCN aqueous solutions were determined with the method. In the crystalline samples, the closest anion distance was determined to be 3.9 ± 0.3 Å, consistent with the XRD result. In the 1.8 and 1 M KSCN aqueous solutions, the anion distances in the ion clusters were determined to be 4.4 ± 0.4 Å. The clustered anion distances in aqueous solutions are very similar to the closest anion distance in the KSCN crystal but significantly shorter than the average anion distance (0.94-1.17 nm) in the aqueous solutions if ion clustering did not occur. The result suggests that ions in the strong electrolyte aqueous solutions can form clusters inside of which they have direct contact with each other.

Enhanced Treatment Options for Dural Arteriovenous Fistulas at the Craniocervical Junction: Endovascular Embolization Versus Microsurgery? A Single-Center 23-Year Experience.

OBJECTIVE: The occurrence of dural arteriovenous fistulas (DAVFs) at the craniocervical junction (CCJ) is an uncommon vascular malformation. The diagnosis and treatment of CCJ DAVFs present a formidable challenge. This study aims to investigate the effect of endovascular embolization and microsurgery on improving patient prognosis. METHODS: This retrospective study included patients diagnosed with CCJ DAVFs who received treatment at the First Affiliated Hospital of Fujian Medical University between January 2000 and January 2023. The clinical records, imaging data, and treatment methods were obtained from the hospital's medical record system. The patients were classified into microsurgery and embolization groups based on the surgical technique employed for treatment. The primary outcome measures were surgical-associated neurological dysfunction (SAND) and long-term neurological outcomes. The Cox proportional hazard regression was utilized to determine hazard ratios and 95% confidence intervals (CI) to assess the relationship between treatment methods and prognosis. Kaplan-Meier survival analysis was employed to evaluate the incidence of SAND in both cohorts. RESULTS: This study recruited 46 patients with an average age of 53.72 ± 13.83 years. In the microsurgery group, there were 12 cases (26.1%) observed. While in the embolization group, there were 34 cases (73.9%). Of these patients, 16 (34.8%) experienced SAND after treatment. In the microsurgery group, there were 8 cases (75.0%), while in the embolization group, only 8 cases (23.5%) were reported. Specifically, the embolization group exhibited a significantly lower risk of SAND [adjusted hazard ratio = 0.259, 95% CI = 0.096-0.700; P = 0.008)] compared to the microsurgery group. Additionally, the combined Borden grade 2-3 was found to be significantly associated with SAND (adjusted hazard ratio = 3.150, 95% CI = 1.132-8.766; P = 0.028). The results of the Kaplan-Meier survival analysis indicated a statistically significant difference in the occurrence of favorable functional outcomes between the 2 groups (log-rank P = 0.0081). CONCLUSIONS: CCJ DAVFs are uncommon disorders characterized by a diverse range of clinical manifestations. The functional prognosis of endovascular treatment may be superior to microsurgery.

Real-time observation of two distinctive non-thermalized hot electron dynamics at MXene/molecule interfaces.

The photoinduced non-thermalized hot electrons at an interface play a pivotal role in determining plasmonic driven chemical events. However, understanding non-thermalized electron dynamics, which precedes electron thermalization (~125 fs), remains a grand challenge. Herein, we simultaneously captured the dynamics of both molecules and non-thermalized electrons in the MXene/molecule complexes by femtosecond time-resolved spectroscopy. The real-time observation allows for distinguishing non-thermalized and thermalized electron responses. Differing from the thermalized electron/heat transfer, our results reveal two non-thermalized electron dynamical pathways: (i) the non-thermalized electrons directly transfer to attached molecules at an interface within 50 fs; (ii) the non-thermalized electrons scatter at the interface within 125 fs, inducing adsorbed molecules heating. These two distinctive pathways are dependent on the irradiating wavelength and the energy difference between MXene and adsorbed molecules. This research sheds light on the fundamental mechanism and opens opportunities in photocatalysis and interfacial heat transfer theory.

Relative intermolecular orientation probed via molecular heat transport.

In this work, through investigating a series of liquid, glassy, and crystalline samples with ultrafast multiple-mode 2D IR and IR transient absorption methods, we demonstrated that the signal anisotropy of vibrational relaxation-induced heat effects is determined by both relative molecular orientations and molecular rotations. If the relative molecular orientations are randomized or molecular rotations are fast compared to heat transfer, the signal anisotropy of heat effects is zero. If the relative molecular orientations are anisotropic and the molecular rotations are slow, the signal anisotropy of heat effects can be nonzero, which is determined by the relative orientations of the energy source mode and the heat sensor mode within the same molecule and in different molecules. We also demonstrated that the correlation between the anisotropy value of heat signal and the relative molecular orientations can be quantitatively calculated.

Vibrational cross-angles in condensed molecules: a structural tool.

The fluctuations of three-dimensional molecular conformations of a molecule in different environments play critical roles in many important chemical and biological processes. X-ray diffraction (XRD) techniques and nuclear magnetic resonance (NMR) methods are routinely applied to monitor the molecular conformations in condensed phases. However, some special requirements of the methods have prevented them from exploring many molecular phenomena at the current stage. Here, we introduce another method to resolve molecular conformations based on an ultrafast MIR/T-Hz multiple-dimensional vibrational spectroscopic technique. The model molecule (4'-methyl-2'-nitroacetanilide, MNA) is prepared in two of its crystalline forms and liquid samples. Two polarized ultrafast infrared pulses are then used to determine the cross-angles of vibrational transition moment directions by exciting one vibrational band and detecting the induced response on another vibrational band of the molecule. The vibrational cross-angles are then converted into molecular conformations with the aid of calculations. The molecular conformations determined by the method are supported by X-ray diffraction and molecular dynamics simulation results. The experimental results suggest that thermodynamic interactions with solvent molecules are not altering the molecular conformations of MNA in the solutions to control their ultimate conformations in the crystals.

Comprehensive Analysis of Regulated Cell Death in Intracranial Aneurysms.

BACKGROUND: Abnormalities in regulated cell death (RCD) are involved in multiple diseases. However, the role of RCD in intracranial aneurysms (IA) remains unknown. The aim of this study was to explore different RCD processes in the pathogenesis of IA. METHODS: Four microarray datasets (GSE75436, GSE54083, GSE13353, GSE15629) and one RNA sequencing (RNA-seq) dataset (GSE122897) were extracted from the Gene Expression Omnibus (GEO) database. The microarray datasets were merged to form the training set, while the RNA-seq dataset was used as the validation set. Differentially expressed genes (DEGs), gene set enrichment analysis (GSEA), and gene set variation analysis (GSVA) were used to investigate the role of different types of RCD, including apoptosis, necroptosis, autophagy, ferroptosis and pyroptosis in the formation of IA. A novel cell death classification system for IA was established using an unsupervised consensus clustering algorithm based on cell death signature genes. Differences in functional enrichment, cell death-related regulators, and immune infiltration between two cell death clusters were evaluated. Finally, predictive genes were identified using the least absolute shrinkage and selection operator (LASSO) regression, random forest and logistic regression, allowing a prediction model to be constructed for IA rupture. RESULTS: Multiple RCD processes were significantly activated in IAs compared to controls. A total of 33 signature genes related to cell death were identified. The IA samples were divided into two clusters based on the cell death signature. The cell death-high subtype had a relatively higher rate of rupture, and higher enrichment levels for multiple cell death processes and several signal transduction and immune-related pathways. Immune infiltration analysis showed that cell death scores were correlated with multiple immune cell types, including macrophages, mast cells, T cells and B cells. A six-gene prediction model was constructed to predict rupture. The area under curves (AUCs) for predicting rupture in the training and validation cohorts were 0.924 and 0.855, respectively. CONCLUSIONS: Comprehensively analysis of RCD in IA and found that multiple RCD types are likely to be involved in IA formation and rupture. These cell death processes were correlated with inflammation and immunity. We present novel insights into the mechanism of IA pathogenesis that should help to guide further research.

RIIß-PKA in GABAergic Neurons of Dorsal Median Hypothalamus Governs White Adipose Browning.

The RIIß subunit of  cAMP-dependent protein kinase A (PKA) is expressed in the brain and adipose tissue. RIIß-knockout mice show leanness and increased UCP1 in brown adipose tissue. The authors have previously reported that RIIß reexpression in hypothalamic GABAergic neurons rescues the leanness. However, whether white adipose tissue (WAT) browning contributes to the leanness and whether RIIß-PKA in these neurons governs WAT browning are unknown. Here, this work reports that RIIß-KO mice exhibit a robust WAT browning. RIIß reexpression in dorsal median hypothalamic GABAergic neurons (DMH GABAergic neurons) abrogates WAT browning. Single-cell sequencing, transcriptome sequencing, and electrophysiological studies show increased GABAergic activity in DMH GABAergic neurons of RIIß-KO mice. Activation of DMH GABAergic neurons or inhibition of PKA in these neurons elicits WAT browning and thus lowers body weight. These findings reveal that RIIß-PKA in DMH GABAergic neurons regulates WAT browning. Targeting RIIß-PKA in DMH GABAergic neurons may offer a clinically useful way to promote WAT browning for treating obesity and other metabolic disorders.

High Plasma Fibrinogen Level Elevates the Risk of Cardiac Complications Following Spontaneous Intracerebral Hemorrhage.

BACKGROUND: Cardiac complications are related to poor prognosis after spontaneous intracerebral hemorrhage (ICH). This study aims to predict the cardiac complications arising from small intracranial hematoma at ultraearly stage. METHODS: The data of this work were derived from the Risk Stratification and Minimally Invasive Surgery in Acute ICH Patients study (ClinicalTrials.gov Identifier: NCT03862729). This work included patients with ICH but without brain herniation, as confirmed by a brain computed tomography scan within 48 hours of symptom onset. Every Patient's information recorded at the emergent department, including clinical, laboratory, electrocardiogram, and medical records, was derived from the electronic data capture. Cardiac complications were defined as the occurrence of myocardial damage, arrhythmias, and ischemic electrocardiogram changes during hospitalization. Variables associated with cardiac complications were filtrated by univariate and multivariate regression analyses. Independent risk factors were used to form the early predictive model. The restricted cubic splines were employed to investigate the nonlinear associations in a more sophisticated and scholarly manner. RESULTS: A total of 587 ICH patients were enrolled in this work, including 72 patients who suffered from cardiac complications after ICH. Out of the 78 variables, 24 were found to be statistically significant in the univariate logistic regression analysis. These significant variables were then subjected to multivariate logistic regression analysis and utilized for constructing risk models. Multivariate logistic regression analysis showed high plasma fibrinogen (FIB) level [odds ratio (OR) per standard deviation (SD) 1.327, 95% confidence intervals (CI) 1.037-1.697; P = 0. 024)] and older age (OR per SD 1.777, 95% CI 1.344-2.349; P ＜0.001) were associated with a higher incidence of cardiac complications after ICH. High admission pulse rate (OR 0.620, 95% CI 0.451-0.853; P = 0. 003) was considered a protective factor for cardiac complications after ICH. In the restricted cubic spline regression model, FIB and cardiac complications following ICH were positively correlated and almost linearly (P for nonlinearity = 0.073). The reference point for FIB in predicting cardiac complications after ICH was 2.64 g/L. CONCLUSIONS: Emergent factors, including plasma FIB level, age, and pulse rate, might be independently associated with cardiac complications after ICH, which warrants attention in the context of treatment.

Simultaneous capturing phonon and electron dynamics in MXenes.

Plasmonic MXenes are of particular interest, because of their unique electron and phonon structures and multiple surface plasmon effects, which are different from traditional plasmonic materials. However, to date, how electronic energy damp to lattice vibrations (phonons) in MXenes has not been unraveled. Here, we employed ultrafast broadband impulsive vibrational spectroscopy to identify the energy damping channels in MXenes (Ti3C2Tx and Mo2CTx). Distinctive from the well-known damping pathways, our results demonstrate a different energy damping channel, in which the Ti3C2Tx plasmonic electron energy transfers to coherent phonons by nonthermal electron mediation after Landau damping, without involving electron-electron scattering. Moreover, electrons are observed to strongly couple with A1g mode (~60 fs, 85-100%) and weakly couple with Eg mode (1-2 ps, 0-15%). Our results provide new insight into the electron-phonon interaction in MXenes, which allows the design of materials enabling efficient manipulation of electron transport and energy conversion.

Nonresonant and resonant mode-specific intermolecular vibrational energy transfers in electrolyte aqueous solutions.

The donor/acceptor energy mismatch and vibrational coupling strength dependences of interionic vibrational energy transfer kinetics in electrolyte aqueous solutions were investigated with ultrafast multiple-dimensional vibrational spectroscopy. An analytical equation derived from the Fermi's Golden rule that correlates molecular structural parameters and vibrational energy transfer kinetics was found to be able to describe the intermolecular mode specific vibrational energy transfer. Under the assumption of the dipole-dipole approximation, the distance between anions in the aqueous solutions was obtained from the vibrational energy transfer measurements, confirmed with measurements on the corresponding crystalline samples. The result demonstrates that the mode-specific vibrational energy transfer method holds promise as an angstrom molecular ruler.