Delirium Mediated the Association Between a History of Falls and Short-Term Mortality Risk in Critically Ill Ischemic Stroke Patients.

Patients with ischemic stroke have an increased propensity to fall, resulting in significant physical and psychological distress. This study examined the association between falls in the 3 months prior to intensive care unit (ICU) admission and mortality within 28 days among 2950 adult ICU patients diagnosed with ischemic stroke from 2008 to 2019, focusing on the potential mediating role of delirium. The primary outcomes were short-term mortality (28, 60, and 90 days) and the risk of delirium. Each patient was followed for at least 1 year. Delirium was primarily assessed using the Confusion Assessment Method for the ICU and by reviewing nursing notes. Group differences between patients with and without a history of falls were compared using the Wilcoxon rank-sum test or the chi-squared test. Cox proportional risk or logistic regression models were used to explore the association between fall history and outcomes, and causal mediation analysis was performed. Results showed that patients with a recent fall history had a significantly increased risk of 28-day (hazard ratio [HR]: 1.62, 95% confidence interval [CI]: 1.35-1.94), 60-day (HR: 1.67, 95% CI: 1.42-1.98), and 90-day mortality (HR: 1.66, 95% CI: 1.41-1.95), as well as an increased risk of delirium (odds ratio: 2.00, 95% CI: 1.66-2.42). Delirium significantly mediated the association between fall history and 28-day mortality (total effect: HR: 1.77, 95% CI: 1.45-2.16; natural indirect effect: HR: 1.12, 95% CI: 1.05-1.21; proportion mediated: 24.6%). These findings suggest that ischemic stroke patients with a recent fall have an increased risk of short-term mortality, partly mediated by delirium. Strategies aimed at preventing delirium may potentially improve prognosis in this patient population.

A novel high sensitive, specificity duplex enzyme-activated differentiating probes PCR method for the SNP detection and differentiation of MS-H vaccine strains from wild-type Mycoplasma synoviae strains.

Mycoplasma synoviae (MS) is a contagious pathogen that poses a significant threat to the poultry industry. Detection plays an important role in the prevention and control of MS, particularly in differentiating between wild-type MS and live attenuated vaccine strains for vaccination selection and culling of animals with wild-type only. The live attenuated ts+ vaccine strain MS-H is recognized as the most effective and widely used vaccine. In this study, we have developed a method called double enzyme-activated differentiation probes PCR (DEA-probes PCR) for the differentiation of MS-H vaccine strain from wild-type strain by targeting the single nucleotide polymorphism (SNP) of the 367th nucleotide in the Obg gene sequence. We developed 2 modified probes with the ribonucleotide insert. When the probe perfectly complements with the target, the ribonuclease H2 (RNase H2) will cleave the ribonucleotide, resulting in the generation of fluorescent signal. With a detection limit of 5.8 copies/µL, the DEA-probes PCR method demonstrates 100% specificity in distinguishing wild-type MS from MS-H strains in 1 h. The method demonstrated great performance in real application of 100 superior palate cleft swab samples from chickens in poultry farms. Twenty-eight samples were detected as MS positive, consistent with the results of the Chinese industry standard method. Additionally, our method was able to distinguish 19 wild-type MS strains from 9 MS-H vaccine strains. The DEA-probes PCR method is rapid, specific and sensitive for SNP detection, overcoming the misidentification in MS detection and differentiation. It can be also applied to the differentiation of infected from vaccinated animals (DIVA) for other pathogens.

Enhanced Diagnostic Efficiency of Endometrial Carcinogenesis and Progression in Women with Abnormal Uterine Bleeding through Peripheral Blood Cytokine Testing: A Multicenter Retrospective Cohort Study.

Objective: This study aimed to evaluate the role of plasma cytokine detection in endometrial cancer screening and tumor progression assessment in patients with abnormal uterine bleeding. Methods: In this multicenter retrospective cohort study of 287 patients with abnormal uterine bleeding, comprehensive clinical information and laboratory assessments, including cytokines, routine blood tests, and tumor markers, were performed. Associations between the clinical indicators and endometrial carcinogenesis/progression were evaluated. The independent risk factors for endometrial cancer and endometrial cancer with deep myometrial invasion were analyzed using multivariate binary logistic regression. Additionally, a diagnostic model was used to evaluate the predictive efficacy of these identified risk factors. Results: In patients with abnormal uterine bleeding, low IL-4 and high IL-8 levels were independent risk factors for endometrial cancer (p < 0.05). Combining IL-4, IL-8, CA125, and menopausal status improved the accuracy of assessing endometrial cancer risk. The area under curve of the model is 0.816. High IL-6 and IL-8 levels were independent risk factors for deep myometrial invasion in patients with endometrial cancer (p < 0.05). Similarly, combining IL-6, IL-8, and Monocyte counts enhanced the accuracy of assessing endometrial cancer risk with deep myometrial invasion. The area under curve of the model is 0.753. Conclusions: Cytokines such as IL-4, IL-8, and IL-6 can serve as markers for monitoring endometrial cancer and its progression in women with abnormal uterine bleeding.

A CNN-LSTM based deep learning model with high accuracy and robustness for carbon price forecasting: A case of Shenzhen's carbon market in China.

Accurately predicting carbon trading prices using deep learning models can help enterprises understand the operational mechanisms and regulations of the carbon market. This is crucial for expanding the industries covered by the carbon market and ensuring its stable and healthy development. To ensure the accuracy and reliability of the predictions in practical applications, it is important to evaluate the model's robustness. In this paper, we built models with different parameters to predict carbon trading prices, and proposed models with high accuracy and robustness. The accuracy of the models was assessed using traditional survey indicators. The robustness of the CNN-LSTM model was compared to that of the LSTM model using Z-scores. The CNN-LSTM model with the best prediction performance was compared to a single LSTM model, resulting in a 9% reduction in MSE and a 0.0133 shortening of the Z-score range. Furthermore, the CNN-LSTM model achieved a level of accuracy comparable to other popular models such as CEEMDAN, Boosting, and GRU. It also demonstrated a training speed improvement of at least 40% compared to the aforementioned methods. These results suggest that the CNN-LSTM enhances model resilience. Moreover, the practicality of using Z-score to evaluate model robustness is confirmed.

Prediction of nitrous oxide emission of a municipal wastewater treatment plant using LSTM-based deep learning models.

Accurate assessment of greenhouse gas emissions from wastewater treatment plants is crucial for mitigating climate change. N2O is a potent greenhouse gas that is emitted from wastewater treatment plants during the biological denitrification process. In this study, we developed and evaluated deep learning models for predicting N2O emissions from a WWTP in Switzerland. Six key parameters were selected to obtain the optimal LSTM model by adjusting experimental parameter conditions. The optimal parameter condition was achieved with 150 neurons, the tanh activation function, the RMSprop optimization algorithm, a learning rate of 0.001, no dropout regularization, and a batch size of 128. Under the same conditions, we compared the performance of recurrent neural networks (RNNs) and Long Short-Term Memory (LSTM) networks. We found that LSTM models outperformed RNN models in predicting N2O emissions. The optimal LSTM model achieved a 36% improvement in mean absolute error (MAE), a 19% improvement in root mean squared error (RMSE), and a 6.92% improvement in R2 score compared to the RNN model. Additionally, LSTM models demonstrated better resilience to sudden changes in the target sequence, exhibiting a 9.54% higher percentage of explained variance compared to RNNs. These results highlight the potential of LSTM models for accurate and robust prediction of N2O emissions from wastewater treatment plants, contributing to effective greenhouse gas mitigation strategies.

Life cycle cost analysis of solar energy via environmental externality monetization.

Evaluating the embodied environmental impact of solar photovoltaic (PV) technology has been an important topic in addressing the sustainable development of renewable energy. While monetization of environmental externality is a remaining issue, which should be carried out in order to allow for an easy-to-understand comparison between direct economic and external cost. In this study, the environmental impact of solar PV power is monetized through conversion factors between midpoint and endpoint categories of life cycle analysis and the monetization weighting factor. Then, the power generation capacity and generation life of PV and coal-fired power plants are assumed to be consistent in order to compare the total cost of PV and coal-fired power generation. Results show that the cost of PV technology is higher than coal-fired form the base year from 2026 until 2030, taking into account environmental external costs and production costs. However, by 2030, the total cost of coal-fired power will be higher than that of solar PV. The life span cost per kWh is $3.55 for solar PV and $116.25 for coal-fired power. Although solar PV power seems more environmentally effective than coal-fired power in the life span, our results reveal the high environmental external cost of producing solar photovoltaic modules, which reminds us to pay more attention to the environmental impact when conducting cost-benefit analysis of renewable technologies. Without incorporating the environmental cost, the real cost of renewable technology will be underestimated.

Facilitators and barriers of attending BaDuanJin experienced by breast cancer survivors during chemotherapy.

PURPOSE: This study aimed to identify facilitators and barriers to adherence to a Baduanjin program experienced by breast cancer survivors (BCSs) during chemotherapy. METHODS: Semi-structured interviews with 10 BCSs in an interprofessional BaDuanJin program were conducted to understand their experiences, including the facilitators and barriers concerning exercise. Content analysis was performed following the behaviour change wheel (BCW). RESULTS: The following five domains emerged from the analysis: 1) Capacity: Recovery of upper limb function, symptom relief, and emotional release are facilitators; periodic treatment and related symptoms and negative emotions are barriers; 2) Motivation: Reflection on health, positive belief, and weight control are facilitators; a doubtful attitude is a barrier; 3) Opportunity: Recuperating at home is a facilitator; 4) Intervention: Facilitators include simple and gentle exercise at home, comprehensive tutoring by an interprofessional team, treating exercise as a task occurring at a fixed time, and peer support. The hindrances are work and home duties prior to exercise and a lack of group activities; and 5) Policy: Social media promotion and less support from physicians are facilitators and barriers, respectively. CONCLUSION: Identifying facilitators and barriers leads to improved support from health professionals, which is required to provide effective strategies to increase adherence to BaDuanJin exercise.

Evidences for the mechanism of Shenmai injection antagonizing doxorubicin-induced cardiotoxicity.

BACKGROUND: Doxorubicin (DOX) is a widely used antitumor drug. However, its clinical application is limited for its serious cardiotoxicity. The mechanism of DOX-induced cardiotoxicity is attributed to the increasing of cell stress in cardiomyocytes, then following autophagic and apoptotic responses. Our previous studies have demonstrated the protective effect of Shenmai injection (SMI) on DOX-induced cardiotoxicity via regulation of inflammatory mediators for releasing cell stress. PURPOSE: To further investigate whether SMI attenuates the DOX-induced cell stress in cardiomyocytes, we explored the mechanism underlying cell stress as related to Jun N-terminal kinase (JNK) activity and the regulation of autophagic flux to determine the mechanism by which SMI antagonizes DOX-induced cardiotoxicity. STUDY DESIGN: The DOX-induced cardiotoxicity model of autophagic cell death was established in vitro to disclose the protected effects of SMI on oxidative stress, autophagic flux and JNK signaling pathway. Then the autophagic mechanism of SMI antagonizing DOX cardiotoxicity was validated in vivo. RESULTS: SMI was able to reduce the DOX-induced cardiomyocyte apoptosis associated with inhibition of activation of the JNK pathway and the accumulation of reactive oxygen species (ROS). Besides, SMI antagonized DOX cardiotoxicity, regulated cardiomyocytes homeostasis by restoring DOX-induced cardiomyocytes autophagy. Under specific circumstances, SMI depressed autophagic process by reducing the Beclin 1-Bcl-2 complex dissociation which was activated by DOX via stimulating the JNK signaling pathway. At the same time, SMI regulated lysosomal pH to restore the autophagic flux which was blocked by DOX in cardiomyocytes. CONCLUSION: SMI regulates cardiomyocytes apoptosis and autophagy by controlling JNK signaling pathway, blocking DOX-induced apoptotic pathway and autophagy formation. SMI was also found to play a key role in restoring autophagic flux for counteracting DOX-damaged cardiomyocyte homeostasis.

Multi-watt, broadband second-harmonic-generation in MgO:PPSLT waveguides fabricated with femtosecond laser micromachining.

We demonstrate optical waveguides fabricated in periodically poled MgO-doped stoichiometric lithium tantalate crystals using an fs-laser direct-write process. Two different waveguide architectures were developed: depressed cladding and stress-induced waveguides. Our strain-optic simulations confirmed the guiding mechanism for either case. We demonstrate designs optimized for low propagation loss (0.52 dB/cm) for both fundamental (1050 nm) and second-harmonic wavelengths (525 nm). Low-power CW second-harmonic-generation studies show normalized efficiencies comparable to that of annealed reverse-proton-exchange waveguides in lithium niobate. High-power studies demonstrate second-harmonic power levels up to 8.5 W in a single-pass configuration, using a 1-nm bandwidth CW IR fiber laser as a pump.

High-energy sub-phonon lifetime pulse compression by stimulated Brillouin scattering in liquids.

Multi-Joule level stimulated Brillouin scattering (SBS) pulse compression below the acoustic phonon lifetime is demonstrated with a energy-scalable generator-amplifier setup. Single-pass compression of pulses longer than 20τB (τB as phonon lifetime) to as short as 0.5τB with ~100 mJ pulse energy is realized from the generator, by choosing the focusing length to match approximately with the full length at half maximum of the input Gaussian pulses. The interaction length is identified, both experimentally and numerically, as the key parameter in achieving sub-phonon lifetime pulse compression, with its main mechanism being the steepening of the Stokes pulse trailing edge via energy exchange process. After combining the generator with an amplifier that involves only collimated beams and serves as energy booster, the compression of 9 ns, 2 J pulses at 532 nm into 170 ps, 1.3 J per pulse is achieved in water, with very good stability in both pulse energy and duration. This work demonstrates for the first time the efficient high-energy SBS sub-phonon lifetime pulse compression, and paves a way to the reliable generation of sub-200 ps laser pulses with Joule-level energy.

Simultaneous determination and pharmacokinetics of eight ginsenosides by LC-MS/MS after intravenously infusion of 'SHENMAI' injection in dogs.

SHENMAI injection, a prescription comprised of Panax ginseng and Ophiopogon japonicas, is being extensively applied in the field of cardio-protection and immune-modulation in China. Ginsenosides are the main active components in SHENMAI injection. In order to capture and analyze the pharmacokinetic profile of major ginsenosides of SHENMAI injection in Beagle dogs, liquid chromatography equipped with electro-spray ionization and tandem mass spectrometry method was applied in simultaneous determination for protopanaxatriol type ginsenoside (Re, Rf, Rg1), protopanaxadiol type ginsenoside (Rb2, Rb1, Rd, Rc) and oleanolic acid type ginsenoside (Ro). A C18 column (150 × 2.1mm, 5µm) and a linear gradient program were used to achieve chromatographic separation, with 0.02% acetic acid solution and acetonitrile. I.S. and ginsenosides were detected by LC-MS/MS in selective reaction mode. Good linearity spanning 5- 1500ng/mL was achieved with the R2 values higher than 0.99 for all analytes. Limit of quantification of all analytes were 3ng/mL. Intra- and inter-day precisions ranges from 0.47 to15.68 % and accuracies were within the range of 85.27-117.57%. Validated analyzing method was then used in the pharmacokinetic experiment for SMI in dogs. The results showed that the pharmacokinetic profile of protopanaxadiol, protopanaxatriol and oleanolic acid type ginsenoside were significant difference in dogs. Protopanaxadiol type ginsenosides exhibited an extremely higher level of exposure and a much slower elimination process. Whereas protopanaxatriol type ginsenosides were quickly eliminated. We concluded that 20 (S) - protopanaxadiol type ginseno sides could be a potential pharmacokinetic marker of SHENMAI injection.

Exosome-derived microRNAs contribute to prostate cancer chemoresistance.

Certain microRNAs (miRNAs) play a key role in cancer cell chemoresistance. However, the pleiotropic functions of exosome-derived miRNAs on developing chemoresistance remain unknown. In the present study, we aimed to construct potential networks of miRNAs, which derived from the exosome of chemoresistant prostate cancer (PCa) cells, with their known target genes using miRNA expression profiling and bioinformatic tools. Global miRNA expression profiles were measured by microarray. Twelve miRNAs were initially selected and validated by qRT-PCR. Known targets of deregulated miRNAs were utilized using DIANA-TarBase database v6.0. The incorporation of deregulated miRNAs and target genes into KEGG pathways were utilized using DIANA-mirPath software. To construct potential miRNA regulatory networks, the overlapping parts of miRNAs and their targer genes from the selected KEGG pathway 'PCa progression (hsa05215)' were visualized by Cytoscape software. We identified 29 deregulated miRNAs, including 19 upregulated and 10 downregulated, in exosome samples derived from two kinds of paclitaxel resistance PCa cells (PC3-TXR and DU145-TXR) compared with their parental cells (PC3 and DU145). The enrichment results of deregulated miRNAs and known target genes showed that a few pathways were correlated with several critical cell signaling pathways. We found that hub hsa-miR3176, -141-3p, -5004-5p, -16-5p, -3915, -488­3p, -23c, -3673 and -3654 were potential targets to hub gene androgen receptor (AR) and phosphatase and tensin homolog (PTEN). Hub gene T-cell factors/lymphoid enhancer-binding factors 4 (TCF4) target genes were mainly regulated by hub hsa-miR-32-5, -141-3p, -606, -381 and -429. These results may provide a linkage between PCa chemoresistance and exosome regulatory networks and thus lead us to propose that AR, PTEN and TCF4 genes may be the important genes which are regulated by exosome miRNAs in chemoresistance cancer cells.

A Unique Pattern of HCV Genotype Distribution on Hainan Island in China Revealed by Evolutionary Analysis.

BACKGROUND/AIMS: Different genotypes of HCV may differ in both disease progression and response to antiviral therapies. Hainan Island has been inhabited by the "Li" aboriginal minority for centuries. We aimed to provide a better understanding of HCV infection on Hainan Island, so that the information would help improve strategies for HCV prevention and control on the island and in the wider country. METHODS: Using RT-PCR and DNA sequencing, we determined HCV sequences from 100 patients living on Hainan Island. RESULTS: Phylogenetic analysis classified these sequences into six subtypes: 6a (n=35), 1b (n=31), 3b (n=16), 2a (n=8), 3a (n=6), and 1a (n=4). By including reference sequences reported from elsewhere in China, phylogeographic trees were reconstructed to indicate their migration patterns. While the predominant 6a isolates were estimated to have origins in Guangdong and Guangxi provinces, the increase in 3b strains must have resulted from IDU network transmission from the southwest. A Bayesian Skyline Plot for subtype 1a, which is rare in China, showed a rapid population growth since 1998. Although slowed in rate around 2005, this growth continued to the present. Not found for any other HCV lineage. CONCLUSIONS: Overall, a delayed growth pattern may indicate the unique history of 1a dissemination in China and its recently increasing prevalence, despite measures taken to improve HCV prevention.

Polysaccharide Extracted from Laminaria japonica Delays Intrinsic Skin Aging in Mice.

This study aimed to determine the effect of topically applied Laminaria polysaccharide (LP) on skin aging. We applied ointment containing LP (10, 25, and 50 µg/g) or vitamin E (10 µg/g) to the dorsal skin of aging mice for 12 months and young control mice for 4 weeks. Electron microscopy analysis of skin samples revealed that LP increased dermal thickness and skin collagen content. Tissue inhibitor of metalloprotease- (TIMP-) 1 expression was upregulated while that of matrix metalloproteinase- (MMP-) 1 was downregulated in skin tissue of LP-treated as compared to untreated aging mice. Additionally, phosphorylation of c-Jun N-terminal kinase (JNK) and p38 was higher in aging skin than in young skin, while LP treatment suppressed phospho-JNK expression. LP application also enhanced the expression of antioxidative enzymes in skin tissue, causing a decrease in malondialdehyde levels and increases in superoxide dismutase, catalase, and glutathione peroxidase levels relative to those in untreated aging mice. These results indicate that LP inhibits MMP-1 expression by preventing oxidative stress and JNK phosphorylation, thereby delaying skin collagen breakdown during aging.

Spatio-temporal characterization of pulses obtained from a high-energy sub-nanosecond laser system.

Spatio-temporal profiles of laser pulses, obtained from each stage of a high-energy sub-nanosecond laser system, are investigated. The laser system is composed of a Q-switched Nd:YAG unstable oscillator, a chain of Nd:YAG amplifiers, a second-harmonic generator, and a high-energy pulse compressor based on stimulated Brillouin scattering (SBS). A curved energy front, i.e., the pulses emerging away from the beam center being gradually delayed from the center pulse, is shown to originate from the unstable oscillator. Our comparative study shows that injection seeding will enlarge the energy front curvature, via reduction of the effective gain. After the laser amplifiers, the energy front curvature is more than doubled due to the gain saturation effect. The latter also modifies the spatial pulse width distribution. While there is a negligible pulse duration spread across the oscillator beam, the amplified pulses are found to have gradually reduced pulse duration away from the beam center. More interestingly, after the SBS pulse compression, not only the pulse width but also the delay is compressed down. This is, to the best of our knowledge, the first study of the spatio-temporal profile of the SBS compressed pulse. To compare with the experiments, two numerical models are developed to simulate the evolution of spatio-temporal profiles within the Nd:YAG laser system and during the SBS pulse compression, respectively. The first model is demonstrated to reproduce the experimental results very well, while the second model predicts part of the features of the SBS compressed pulse. The limitation on the latter is discussed.

Hepatoma cell-derived leptin downregulates the immunosuppressive function of regulatory T-cells to enhance the anti-tumor activity of CD8+ T-cells.

The adaptive immune response against hepatocellular carcinoma (HCC) could be a therapeutic target to restrain HCC initiation and growth. The interactions between hepatoma cells and immune cells modify the anti-tumor immunity to influence hepatoma cell survival. To explore the potential interplay between hepatoma cells and anti-HCC T-cells, we conducted a HCC induction mouse model to analyze the phenotypic and functional alterations of T-cell subsets. We found that both hepatoma tissues and hepatoma cell lines substantially produced higher leptin, which is an adipokine usually expressed in fat tissue, than normal liver tissue or hepatocytes. We also found that regulatory T-cells (Tregs), effector CD4(+) T-cells and CD8(+) T-cells upregulated expression of leptin receptor (LEPR) in spleens and livers after HCC induction. In vitro study showed that macrophages and dendritic cells isolated from HCC livers upregulated LEPR expression on T-cells. Leptin inhibited Treg activation and function in vitro, demonstrated by lower expression of TGF-ß, IL-10, CTLA4 and GITR in Tregs, as wells weaker suppression of CD8(+) T-cell proliferation and production of cytotoxic mediators. In addition, silencing LEPR in Tregs favored tumor growth in a hepatoma cell line allograft model. Taken together, our study suggests that hepatoma cells could enhance anti-HCC immunity through secreting leptin to down-regulate Treg activity and subsequently promote CD8(+) T-cell response.

Diagnostic value of serum Golgi protein 73 for HBV-related primary hepatic carcinoma.

BACKGROUND: Alpha-fetoprotein (AFP) levels are routinely used for diagnosis and monitoring of hepatic diseases, but it has a limited value. Golgi protein 73 (GP73) has been suggested as a new marker for hepatic diseases. OBJECTIVE: To explore the clinical value of serum GP73 in different diseases associated with hepatitis B virus (HBV) infection. METHOD: Between January 2010 and August 2014, serum samples from 88 patients with chronic hepatitis B (CHB), 78 patients with HBV-related liver cirrhosis (LC), and 194 patients with HBV-related primary hepatic cancer (PHC) were collected. Serum samples from 30 healthy volunteers were used as controls. ELISA and microparticle enzyme immunoassay were used to measure serum GP73 and AFP levels. Receiver operating characteristic (ROC) curves were used to analyze the diagnostic value of serum GP73 and AFP for PHC. RESULTS: For the diagnosis of PHC, GP73 showed a sensitivity of 65.5% and specificity of 66.3%, while AFP levels showed sensitivity of 64.4% and specificity of 76.5%. Serial testing (both tests are positive) could increase the specificity (sensitivity of 45.9% and specificity of 85.5%) while parallel testing (any single positive test result) could increase the sensitivity (sensitivity of 84.0% and specificity of 57.2%). Serum GP73 and AFP levels were significantly different between Child-Pugh grades (P<0.001 for GP73 and P=0.044 for AFP). Significant differences in serum GP73 and AFP were found between TNM stages (all P<0.001). CONCLUSION: Serum GP73 had limited diagnostic value for HBV-related PHC. The combined use of serum GP73 and AFP levels improved the diagnostic efficacy.

Ring-shaped backward stimulated Raman scattering driven by stimulated Brillouin scattering.

Backward stimulated Raman scattering is generated in water, pumped by pre-compressed pulses from a single-cell stimulated Brillouin scattering pulse compressor. The maximum energy efficiency of 9% is achieved by employing a circularly-polarized pump pulse at its energy of 50 mJ, around which point the backward stimulated Raman scattering also exhibits a ring-shaped profile. The correlations between spatial and temporal profiles as well as the intensities of the backward stimulated Raman and the stimulated Brillouin scattering generated from Raman cell indicate that the ring-shaped backward stimulated Raman is driven by intense stimulated Brillouin scattering. We demonstrate the latter process to be much more efficient for the backward Raman generation than the conventional process in which the laser itself pumps a backward stimulated Raman beam. It is shown that a further increase in pump energy leads to a drop in efficiency, combined with a break-up of the ring pattern of backward stimulated Raman. These effects are associated with filament generation above a certain threshold.

Generation of 300 ps laser pulse with 1.2 J energy by stimulated Brillouin scattering in water at 532 nm.

We demonstrate high-energy pulse compression by stimulated Brillouin scattering (SBS) in water using an energy-scalable generator amplifier setup. Pulse compression from 2.4 J, 12 ns at 532 nm to 1.2 J, 300 ps has been achieved, which to our knowledge represents the highest compressed energy achieved at 532 nm using SBS and is only limited by the size of our optics. Our setup is robust and stable over long periods of operation (2% of energy fluctuation and <3% shot-to-shot variation of pulse width).

Optimizing sub-ns pulse compression for high energy application.

We demonstrate ∼ 40X pulse compression (down to ∼ 300 ps) with ∼ 1 joule, nanosecond pulses for high energy applications requiring ≥ 1 gigawatt of peak power. Our method is based on the established principle of stimulated Brillouin scattering (SBS). To push the SBS technique to its highest peak-power limit, a combination of theoretical modeling and experiments is used to identify and optimize all critical parameters, including optical configuration, interaction length, intensity matching, choice of gain medium and thermal stability. Pulse compression results are presented both at 1064 nm and 532 nm, with performances close to the theoretical limit and excellent shot-to-shot reproducibility.