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Fe(III)-oxalate complexes are ubiquitous in atmospheric environments, which can release reactive oxygen species (ROS) such as H

Aerosol microdroplets as microreactors for many important atmospheric reactions are ubiquitous in the atmosphere. pH largely regulates the chemical processes within them; however, how pH and chemical species spatially distribute within an atmospheric microdroplet is still under intense debate. The challenge is to measure pH distribution within a tiny volume without affecting the chemical species distribution. We demonstrate a method based on stimulated Raman scattering microscopy to visualize the three-dimensional pH distribution inside single microdroplets of varying sizes. We find that the surface of all microdroplets is more acidic, and a monotonic trend of pH decreasing is observed in the 2.9-μm aerosol microdroplet from center to edge, which is well supported by molecular dynamics simulation. However, bigger cloud microdroplet differs from small aerosol for pH distribution. This size-dependent pH distribution in microdroplets can be related to the surface-to-volume ratio. This work presents noncontact measurement and chemical imaging of pH distribution in microdroplets, filling the gap in our understanding of spatial pH in atmospheric aerosol.

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Focal therapy (FT) has been proposed as an approach to eradicate clinically significant prostate cancer while preserving the normal surrounding tissues to minimize treatment-related toxicity. Rapid histology of core needle biopsies is essential to ensure the precise FT for localized lesions and to determine tumor grades. However, it is difficult to achieve both high accuracy and speed with currently available histopathology methods. Here, we demonstrated that stimulated Raman scattering (SRS) microscopy could reveal the largely heterogeneous histologic features of fresh prostatic biopsy tissues in a label-free and near real-time manner. A diagnostic convolutional neural network (CNN) built based on images from 61 patients could classify Gleason patterns of prostate cancer with an accuracy of 85.7%. An additional 22 independent cases introduced as external test dataset validated the CNN performance with 84.4% accuracy. Gleason scores of core needle biopsies from 21 cases were calculated using the deep learning SRS system and showed a 71% diagnostic consistency with grading from three pathologists. This study demonstrates the potential of a deep learning–assisted SRS platform in evaluating the tumor grade of prostate cancer, which could help simplify the diagnostic workflow and provide timely histopathology compatible with FT treatment.Significance:A platform combining stimulated Raman scattering microscopy and a convolutional neural network provides rapid histopathology and automated Gleason scoring on fresh prostate core needle biopsies without complex tissue processing.

Focal therapy (FT) has been proposed as an approach to eradicate clinically significant prostate cancer while preserving the normal surrounding tissues to minimize treatment-related toxicity. Rapid histology of core needle biopsies is essential to ensure the precise FT for localized lesions and to determine tumor grades. However, it is difficult to achieve both high accuracy and speed with currently available histopathology methods. Here, we demonstrated that stimulated Raman scattering (SRS) microscopy could reveal the largely heterogeneous histologic features of fresh prostatic biopsy tissues in a label-free and near real-time manner. A diagnostic convolutional neural network (CNN) built based on images from 61 patients could classify Gleason patterns of prostate cancer with an accuracy of 85.7%. An additional 22 independent cases introduced as external test dataset validated the CNN performance with 84.4% accuracy. Gleason scores of core needle biopsies from 21 cases were calculated using the deep learning SRS system and showed a 71% diagnostic consistency with grading from three pathologists. This study demonstrates the potential of a deep learning–assisted SRS platform in evaluating the tumor grade of prostate cancer, which could help simplify the diagnostic workflow and provide timely histopathology compatible with FT treatment.Significance:A platform combining stimulated Raman scattering microscopy and a convolutional neural network provides rapid histopathology and automated Gleason scoring on fresh prostate core needle biopsies without complex tissue processing.

People of all ages consume salt every day, but is it really just salt? Plastic nanoparticles (nanoplastics) polluting the oceans and the atmosphere are posing an increasing environmental threat and have begun to contaminate everyday salt in consumer goods. Herein, we developed a combined Surface Enhanced Raman Scattering (SERS) and Stimulated Raman Scattering (SRS) approach that can simultaneously realize the filtration, enrichment, and detection of nanoplastics in commercial salt. SERS was used to explore the potential types of nanoplastic contaminants in salts. SRS was used to conduct imaging and to quantify the presence of nanoplastics. Nanoplastics in sea salts produced from different sources were studied, with the following nanoplastics detected: polystyrene (PS), polyethylene (PE), polypropylene (PP). We estimate that, depending on location, an average person could be ingesting as many as 63,100 nanoplastics per year through the consumption of sea salt alone. Nanoplastics can readily adsorb organic matter and heavy metal particles, so the potential harm to human health should not be underestimated.

Surgeries achieving maximal tumor resection remain the major effective treatment of pancreatic cancer. Rapid and precise intraoperative diagnosis of pancreatic tissues is critical for optimum surgical outcomes but is challenging for the current staining-based histological methods. We demonstrated that label-free coherent nonlinear optical microscopy with combined stimulated Raman scattering (SRS) and second harmonic generation (SHG) could reveal key diagnostic features of both normal and cancerous human pancreatic tissues. Adjacent pairs of tissue sections from resection margins of 37 patients were imaged by SRS and hematoxylin and eosin staining for direct comparison, demonstrating high diagnostic concordance (Cohen's kappa, κ > 0.97) between them. Fresh unprocessed tissues showed well-preserved histoarchitectures including pancreatic ducts, islets, acini, and nerves. Moreover, the area ratios of collagen fibers were analyzed and found to correlate with the drainage pancreatic amylase level (odds ratio = 28.0, p = 0.0017). Our results indicated that SRS/SHG histology provides potential for rapid intraoperative diagnosis of pancreatic cancer as well as a predictive value of postoperative pancreatic fistula.

Benefiting from the developments of advanced optical microscopy techniques, the mysteries of biological functions at the cellular and subcellular levels have been continuously revealed. Stimulated Raman scattering (SRS) microscopy is a rapidly growing technique that has attracted broad attentions and become a powerful tool for biology and biomedicine, largely thanks to its chemical specificity, high sensitivity and fast image speed. This review paper introduces the principles of SRS, discusses the technical developments and implementations of SRS microscopy, then highlights and summarizes its applications on biological cellular machinery and finally shares our visions of potential breakthroughs in the future.

Coherent longitudinal lattice vibrations of black phosphorus provide unique access to the out-of-plane strain coupled in-plane optical properties. In this work, polarization-resolved femtosecond transient absorption microscopy is applied to study the anisotropic coherent phonon responses. Multiorder phonon harmonics were observed with thickness dependence well explained by the linear chain model, allowing rapid optical mapping of phonon frequency distributions. More interestingly, exotic coherent phonon oscillations occourred with a π-phase jump between the armchair and zigzag polarizations, which reveals opposite signs of photoelasticity under the longitudinal strain. Specifically, compressive strain reduces the imaginary refractive index in the armchair polarization but increases the real refractive index in the zigzag polarization, as confirmed by the ab initio calculations and thin film model. These fundamental properties of black phosphorus hold potential for applications in ultrafast and polarization-sensitive photoacoustic/photoelastic modulators.

ObjectiveIncreasing evidence suggests that impaired cartilage is a substantial risk factor for the progression from hyperuricaemia to gout. Since the relationship between cartilage matrix protein and gout flares remains unclear, we investigated its role in monosodium urate (MSU) crystallisation and following inflammation.MethodsBriefly, we screened for cartilage matrix in synovial fluid from gouty arthritis patients with cartilage injuries. After identifying a correlation between crystals and matrix molecules, we conducted image analysis and classification of crystal phenotypes according to their morphology. We then evaluated the differences between the cartilage matrix protein-MSU complex and the pure MSU crystal in their interaction with immune cells and identified the related signalling pathway.ResultsType II collagen (CII) was found to be enriched around MSU crystals in synovial fluid after cartilage injury. Imaging analysis revealed that CII regulated the morphology of single crystals and the alignment of crystal bows in the co-crystalline system, leading to greater phagocytosis and oxidative stress in macrophages. Furthermore, CII upregulated MSU-induced chemokine and proinflammatory cytokine expression in macrophages, thereby promoting the recruitment of leucocytes. Mechanistically, CII enhanced MSU-mediated inflammation by activating the integrin β1(ITGB1)-dependent TLR2/4-NF-κB signal pathway.ConclusionOur study demonstrates that the release of CII and protein-crystal adsorption modifies the crystal profile and promotes the early immune response in MSU-mediated inflammation. These findings open up a new path for understanding the relationship between cartilage injuries and the early immune response in gout flares.

We report the generation of parabolic pulses with broadband spectrum from a core-pumped Yb-doped fiber amplifier seeded by a dispersion managed fiber oscillator. The net cavity dispersion of Yb-doped oscillator was continuously changed from 0.074 to -0.170 ps2, which enabled us to achieve dissipative soliton, stretched pulse and soliton mode-locking operations. Spectral evolution processes in the core-pumped nonlinear fiber amplifier seeded by various input solitons were investigated experimentally and theoretically. Our finding indicates that cavity dispersion of oscillator can be used to engineer the input pulse parameter for amplifier, thus forming a pre-chirper free fiber amplification structure. In the experiment, we obtained 410-mW parabolic pulses with spectral bandwidth up to 56 nm. In combination with a passively synchronized frequency-doubled Er-doped fiber laser, we have demonstrated coherent anti-Stokes Raman imaging. The compact dual-color fiber laser source may facilitate practical applications of nonlinear biomedical imaging beyond the laboratory environment.

Gastroscopic biopsy provides the only effective way for gastric cancer diagnosis, but the gold standard histopathology is time-consuming and incompatible with gastroscopy. Conventional stimulated Raman scattering (SRS) microscopy has shown promise in label-free diagnosis on human tissues, yet it requires the tuning of picosecond lasers to achieve chemical specificity at the cost of time and complexity. Here, we demonstrated single-shot femtosecond SRS (femto-SRS) could reach the maximum speed and sensitivity with preserved chemical resolution by integrating with U-Net. Fresh gastroscopic biopsy was imaged in < 60 seconds, revealing essential histoarchitectural hallmarks perfectly agreed with standard histopathology. Moreover, a diagnostic neural network (CNN) was constructed based on images from 279 patients that predicts gastric cancer with accuracy > 96%. We further demonstrated semantic segmentation of intratumor heterogeneity and evaluation of resection margins of endoscopic submucosal dissection (ESD) tissues to simulate rapid and automated intraoperative diagnosis. Our method holds potential for synchronizing gastroscopy and histopathological diagnosis.

Precise evaluation of breast tumor malignancy based on tissue calcifications has important practical value in the disease diagnosis, as well as the understanding of tumor development. Traditional X-ray mammography provides the overall morphologies of the calcifications but lacks intrinsic chemical information. In contrast, spontaneous Raman spectroscopy offers detailed chemical analysis but lacks the spatial profiles. Here, we applied hyperspectral stimulated Raman scattering (SRS) microscopy to extract both the chemical and morphological features of the microcalcifications, based on the spectral and spatial domain analysis. A total of 211 calcification sites from 23 patients were imaged with SRS, and the results were analyzed with a support vector machine (SVM) based classification algorithm. With optimized combinations of chemical and geometrical features of microcalcifications, we were able to reach a precision of 98.21% and recall of 100.00% for classifying benign and malignant cases, significantly improved from the pure spectroscopy or imaging based methods. Our findings may provide a rapid means to accurately evaluate breast tumor malignancy based on fresh tissue biopsies.

We propose a composite acousto-optical modulation (AOM) scheme for wide-band, efficient modulation of CW and pulsed lasers. We show that by adjusting the amplitudes and phases of weakly-driven daughter AOMs, diffraction beyond the Bragg condition can be achieved with exceptional efficiencies. Furthermore, by imaging pairs of AOMs in a counter-propagating configuration, high contrast switching of output orders can be achieved at the driving radio frequency (rf) limit, thereby enabling efficient bidirectional routing of a synchronized mode-locked laser. Here we demonstrate a simplest example of such scheme with a double-AOM setup for efficient diffraction across an octave of rf bandwidth, and for routing a mode-locked pulse train with up to $f_{\rm rep}=400$~MHz repetition rate. We discuss extension of the composite scheme toward multi-path routing and time-domain multiplexing, so as to individually shape each pulses of ultrafast lasers for novel quantum control applications., 12 pages, 5 figures, minor revision. a few mistakes fixed

Van der Waals heterostructures obtained by artificially stacking two-dimensional crystals represent the frontier of material engineering, demonstrating properties superior to those of the starting materials. Fine control of the interlayer twist angle has opened new possibilities for tailoring the optoelectronic properties of these heterostructures. Twisted bilayer graphene with a strong interlayer coupling is a prototype of twisted heterostructure inheriting the intriguing electronic properties of graphene. Understanding the effects of the twist angle on its out-of-equilibrium optical properties is crucial for devising optoelectronic applications. With this aim, we here combine excitation-resolved hot photoluminescence with femtosecond transient absorption microscopy. The hot charge carrier distribution induced by photo-excitation results in peaked absorption bleaching and photo-induced absorption bands, both with pronounced twist angle dependence. Theoretical simulations of the electronic band structure and of the joint density of states enable to assign these bands to the blocking of interband transitions at the van Hove singularities and to photo-activated intersubband transitions. The tens of picoseconds relaxation dynamics of the observed bands is attributed to the angle-dependence of electron and phonon heat capacities of twisted bilayer graphene.

Van der Waals heterostructures of monolayer crystals are promising platforms for novel electronic, photonic and spintronic devices [1] - [2] . Fine control of the stacking rotation angle, i.e. the twist angle θ, allows to tailor their electronic and optical properties. In twisted bilayer graphene (tBLG), interlayer coupling leads to a complex subband electronic structure and van Hove singularities (vHs) with θ-dependent energy position [3] .

Coherent anti-Stokes Raman scattering (CARS) can be used to excite vibrational bonds with chemical selectivity, high spatial and spectral resolution, and high sensitivity, which has many applications in biomedical research. The common way to realize CARS imaging is illuminating sample with two synchronized ultra-short pulses. Recent development of various fiber laser schemes based on nonlinear optical effect provides compact laser source for CARS imaging. However, the nonlinear conversion in optical fiber may inevitably introduce temporal or spectral noise to the newly generated pulses. In this paper, we have proposed a polarization-maintaining (PM) passive-synchronized picosecond fiber laser system that generates dual-color picosecond pulses for CARS. An Er-doped fiber laser and a Yb-doped fiber laser were passively synchronized by cross phase modulation based on master-slave injection scheme. In the experiment, the wavelength of one branch was fixed at 791 nm, which was generated by second harmonic generation of Er-doped fiber laser. The wavelength of the other branch can be continuously tuned from 1017-1047 nm, which was obtained by adding an active spectral broadening module and an optical bandpass filter after Yb-doped fiber laser. As a result, the laser source allows to probe vibrational bonds with frequencies difference between 2809 cm-1 and 3091 cm-1 . Finally, the achieved tunable synchronized pulses enabled us to microscopically image mouse ear samples. The compact optical fiber laser proposed with PM fiber design, stable synchronization and large wavelength tunability would become a promising laser source for CARS imaging in clinical use.

Photochromic probes with reversible fluorescence have revolutionized the fields of single molecule spectroscopy and super-resolution microscopy, but lack sufficient chemical specificity. In contrast, Raman probes with stimulated Raman scattering (SRS) microscopy provides superb chemical resolution for super-multiplexed imaging, but are relatively inert. Here we report vibrational photochromism by engineering alkyne tagged diarylethene to realize photo-switchable SRS imaging. The narrow Raman peak of the alkyne group shifts reversibly upon photoisomerization of the conjugated diarylethene when irradiated by ultraviolet (UV) or visible light, yielding “on” or “off” SRS images taken at the photoactive Raman frequency. We demonstrated photo-rewritable patterning and encryption on thin films, painting/erasing of cells with labelled alkyne-diarylethene, as well as pulse-chase experiments of mitochondria diffusion in living cells. The design principle provides potentials for super-resolution microscopy, optical memories and switches with vibrational specificity., Probes with reversible fluorescence are useful in super-resolution microscopy, but lack sufficient chemical specificity. Here, the authors engineer alkyne tagged diarylethene to realize photo-switchable stimulated Raman scattering probes with high chemical resolution, for applications in living cells.

Gout is a common metabolic disease with growing burden, caused by monosodium urate (MSU) microcrystal deposition. In situ and chemical-specific histological identification of MSU is crucial in the diagnosis and management of gout, yet it remains inaccessible for current histological methods. Methods: Stimulated Raman scattering (SRS) microscopy was utilized to image MSU based on its fingerprint Raman spectra. We first tested SRS for the diagnosis capability of gout and the differentiation power from pseudogout with rat models of acute gout arthritis, calcium pyrophosphate deposition disease (CPDD) and comorbidity. Then, human synovial fluid and surgical specimens (n=120) were were imaged with SRS to obtain the histopathology of MSU and collagen fibers. Finally, quantitative SRS analysis was performed in gout tissue of different physiological phases (n=120) to correlate with traditional histopathology including H&E and immunohistochemistry staining. Results: We demonstrated that SRS is capable of early diagnosis of gout, rapid detection of MSU in synovial fluid and fresh unprocessed surgical tissues, and accurate differentiation of gout from pseudogout in various pathophysiological conditions. Furthermore, quantitative SRS analysis revealed the optical characteristics of MSU deposition at different pathophysiological stages, which were found to matched well with corresponding immunofluorescence histochemistry features. Conclusion: Our work demonstrated the potential of SRS microscopy for rapid intraoperative diagnosis of gout and may facilitate future fundamental researches of MSU-based diseases.

We have proposed and implemented a polarization-maintaining passively synchronized fiber laser system, which could deliver tunable dual-color picosecond pulses by including a frequency-doubling module and a spectral broadening module. Specifically, the output from the involved Er-doped fiber laser were used to generate second-harmonic pulses at 790 nm with a quadratic nonlinear crystal. In parallel, the amplified pulses from the synchronized Yb-doped fiber laser were launched into a 150-m single mode fiber, which resulted in not only substantial spectral bandwidth broadening from 0.1 to 20.1 nm, but also a significant Raman-induced signal around 1080 nm. Consequently, narrow spectra from 1018-1051 nm and 1070-1095 nm could be continuously tuned via a tunable bandpass filter, corresponding to Raman bonds from 2835-3143 cm−1 and 3312-3525 cm−1. Finally, the achieved tunable synchronized pulses enabled us to microscopically examine mouse ear samples based on coherent anti-Stokes Raman and second harmonic generation imaging. Therefore, our tunable passively-synchronized fiber laser system would be promising to provide a simple and compact laser source for subsequent coherent Raman microscopy.

Maximal resection of tumor while preserving the adjacent healthy tissue is particularly important for larynx surgery, hence precise and rapid intraoperative histology of laryngeal tissue is crucial for providing optimal surgical outcomes. We hypothesized that deep-learning based stimulated Raman scattering (SRS) microscopy could provide automated and accurate diagnosis of laryngeal squamous cell carcinoma on fresh, unprocessed surgical specimens without fixation, sectioning or staining. Methods: We first compared 80 pairs of adjacent frozen sections imaged with SRS and standard hematoxylin and eosin histology to evaluate their concordance. We then applied SRS imaging on fresh surgical tissues from 45 patients to reveal key diagnostic features, based on which we have constructed a deep learning based model to generate automated histologic results. 18,750 SRS fields of views were used to train and cross-validate our 34-layered residual convolutional neural network, which was used to classify 33 untrained fresh larynx surgical samples into normal and neoplasia. Furthermore, we simulated intraoperative evaluation of resection margins on totally removed larynxes. Results: We demonstrated near-perfect diagnostic concordance (Cohen's kappa, κ > 0.90) between SRS and standard histology as evaluated by three pathologists. And deep-learning based SRS correctly classified 33 independent surgical specimens with 100% accuracy. We also demonstrated that our method could identify tissue neoplasia at the simulated resection margins that appear grossly normal with naked eyes. Conclusion: Our results indicated that SRS histology integrated with deep learning algorithm provides potential for delivering rapid intraoperative diagnosis that could aid the surgical management of laryngeal cancer.

Wenshuo Wang,1,* Huan Liu,1,* Yuntao Lu,1,* Xiaole Wang,2,* Bohan Zhang,3 Shuo Cong,1 Yun Zhao,1 Minbiao Ji,3 Hongyue Tao,4 Lai Wei1,5 1Department of Cardiac Surgery, Zhongshan Hospital, Fudan University, Shanghai 200030, China; 2Department of Radiology, Second People’s Hospital of Nantong City, Nantong 226002, Jiangsu, China; 3State Key Laboratory of Surface Physics and Department of Physics, Fudan University, Shanghai 200433, China; 4Department of Radiology, Zhongshan Hospital, Fudan University, Shanghai 200040, China; 5Department of Cardiac Surgery, Shanghai Public Health Clincal Center, Shanghai 201508, China *These authors contributed equally to this work Background: Hydrogen sulfide (H2S) has shown promising therapeutic benefits in reversing a variety of pathophysiological processes in cardiovascular system, including myocardial ischemia–reperfusion (IR) injury. However, the achievement of controlled and sustained release of H2S has been a technical bottleneck that limits the clinical application of the gas molecule.Methods: The current study describes the development of mesoporous iron oxide nanoparticles (MIONs) which were loaded with diallyl trisulfide (DATS), a H2S donor compound, and calibrated by stimulated Raman scattering/transient absorption.Results: The synthesized MIONs were characterized with excellent mesoporosity and a narrow size distribution, which enabled them to slow down the release of H2S to a suitable rate and prolong the plateau period. The controlled-release feature of DATS-MIONs resulted in little adverse effect both invitro and invivo, and their protective effect on the heart tissue that underwent IR injury was observed in the mouse model of myocardial ischemia. The rapid biodegradation of DATS-MIONs was induced by Kupffer cells, which were specialized macrophages located in the liver and caused limited hepatic metabolic burden.Conclusion: The sustained-release pattern and excellent biocompatibility make DATS-MIONs a promising H2S donor for research and medical purposes. Keywords: steady release, porous structure, biocompatibility, biodegeneration

Percutaneous endoscopic lumbar discectomy (PELD) is the major effective treatment for lumbar disc herniation, and rapid histological identification of dissected tissue is critical to guide the discectomy. In this work, we revealed the histological features of different types of peridural tissues of the lumbar spine by label-free multi-modal nonlinear optical microscopy. Stimulated Raman scattering (SRS) was used to extract lipid and protein distributions, while second harmonic generation (SHG) and two-photon excited fluorescence (TPEF) signals were applied to image the collagen and elastin fibers at the same time. Our results demonstrated that the nonlinear optical features of the dura and adjacent soft tissues were significantly different, showing the potentials of our method for intraoperative differentiation of these critical tissues and improving the surgical outcome of PELD.