Search Results (110)

We report a passively Q-switched self-Raman laser using a dual-end composite c-cut Nd:YVO₄ crystal, which generates switchable visible emissions at 533 nm, 560 nm, and 589 nm. A Cr⁴⁺:YAG/YAG composite crystal served the role of a saturable absorber to achieve passive Q-switching. An angle-tuned BBO crystal was used to achieve the frequency mixing between the first-tokes wave and the fundamental wave. At an incident pump power of 9.5 W, the maximum average output powers were 425 mW for the 589 nm yellow laser, 193 mW for the 560 nm lime laser, and 605 mW for the 533 nm green laser, with corresponding pulse widths of approximately 3.8, 3.6, and 35.1 ns, respectively. This result shows that a passive Q-switching operation with self-Raman crystals presents a promising approach for compact multi-wavelength pulse laser sources. Full article

A continuous-wave (CW) orthogonally polarized single-wavelength red laser (OPSRL) at 698 nm with a tunable power ratio within a wide range between the two polarized components was demonstrated using two Pr³⁺:LiLuF₄ (Pr:LLF) crystals for the first time. Through control of the waist location of the pump beam in the active media, the output power ratio of the two polarized components of the OPSRL could be adjusted. Under pumping by a 20 W, 444 nm InGaN laser diode (LD), a maximum total output power of 4.12 W was achieved with equal powers for both polarized components, corresponding to an optical conversion efficiency of 23.8% relative to the absorbed pump power. Moreover, by a type-II critical phase-matched (CPM) BBO crystal, a CW ultraviolet (UV) second-harmonic generation (SHG) at 349 nm was also obtained with a maximum output power of 723 mW. OPSRLs can penetrate deep tissues and demonstrate polarization-controlled interactions, and are used in bio-sensing and industrial cutting with minimal thermal distortion, etc. The dual-polarized capability of OPSRLs also supports multi-channel imaging and high-speed interferometry. Full article

An orthogonally polarized green dual-wavelength (OPGDW) laser output in a Pr³⁺:LiLuF₄ (Pr:LLF) crystal with the power ratio of 1:1 was realized for the first time. We calculated the condition for obtaining the identical power of the two output wavelengths and achieved the OPGDW laser by adjusting the tilt angle of the intracavity etalon and optimizing the output coupling transmittance. Using a frequency-doubled (2ω) optically pumped semiconductor (OPS) laser of 10 W at 479 nm, a continuous wave (CW) OPGDW laser output at 523 nm (π-polarized) and 538 nm (σ-polarized) was achieved with a combined power of 1.83 W. In addition, by type-II critical phase-matched (CPM) β-BaB₂O₄ (BBO) nonlinear crystal, a 57 mW, 265 nm CW UV laser was also realized by sum-frequency generation (SFG) of 523 nm and 538 nm wavelengths. CW OPGDW lasers with identical power output were ideal for both medical detection and generating UV lasers. Full article

Babesia bovis is a protozoan parasite that causes babesiosis in cattle. It has been hypothesized that in apicomplexan parasites, translationally controlled tumor protein (TCTP) interferes with the host immune response by inhibiting B cell proliferation. The aim of this study was the characterization of B. bovis TCTP (BboTCTP) and the evaluation of its expression, immunogenicity and role in infection. The tctp gene was identified and sequenced from B. bovis isolates and revealed a high conservation. Expression was confirmed in intraerythrocytic stages by Western blot and confocal microscopy. Synthetic peptides containing predicted B cell epitopes were used to immunize cattle, followed by a challenge with a virulent B. bovis strain. Immunized animals showed milder clinical signs and faster recovery compared to controls. Sera from non-immunized animals exhibited lower total IgG levels after challenge (p < 0.05), while sera from immunized animals induced significant in vitro invasion inhibition (32–33%). These results suggest that BboTCTP is immunogenic and may play a role in modulating the host immune response. The results provide novel insights into B. bovis biology and support BboTCTP as a promising candidate for further evaluation as a vaccine antigen. Future studies should explore its immunomodulatory mechanisms and potential use in combined vaccine formulations. Full article

Pakistan’s marine fishing industry is crucial to the country’s economy, generating employment opportunities and foreign revenue. It produces 80% of the country’s total fish production. Otolithes ruber is a commercially important fish on the Makran coast of Pakistan, contributing significantly to the region’s croaker fisheries. This study is the first to apply three length-based approaches for assessing the stock status of O. ruber in the Makran coast: (1) TropFishR to estimate the mortality, growth parameters, and current exploitation status, reference points based on the yield per recruitment model, (2) the length-based Bayesian biomass method (LBB) to calculate stock biomass, and (3) the length-based spawning potential ratio (LBSPR) to estimate the spawning potential ratio. The length–weight relationship of Otolithes ruber was a positive allometric pattern (b = 3.28; R² = 0.94). Growth parameters for Otolithes ruber were L_∞ = 55.47 cm, K = 0.50 year⁻¹. The calculated total mortality rate (Z), natural mortality (M), and fishing mortality (F) were 2.27 year⁻¹, 0.67 year⁻¹, and 1.6 year⁻¹, respectively. The exploitation rate (E) was 0.70, indicating severe overexploitation. The current length at first capture (Lc₅₀) = 27.37 cm was lower than that at first maturity (Lm₅₀) = 30.75 cm, indicating growth overfishing. The current spawning potential ratio (8%) was lower than the optimal value (40%), indicating recruitment overfishing. The current biomass, concerning virgin biomass B/B_o, was also 8%, resulting in a 92% stock decline. We recommend reducing the exploitation pressure by limiting the commercial catch to an optimum length range of 34.5–42.2 cm and reducing fishing pressure by 40% to ensure sustainable fishery management. Full article

Brent oil holds a significant position in the global energy market, as oil prices in many regions are indexed to it. Therefore, forecasting the future price of Brent oil is of great importance. In recent years, artificial intelligence techniques have been widely applied in modeling and prediction tasks. In this study, an Adaptive Neuro-Fuzzy Inference System (ANFIS), a well-established AI approach, was employed for the time-series forecasting of Brent oil prices. To ensure effective learning and improve prediction accuracy, ANFIS was trained using nine different metaheuristic algorithms: Artificial Bee Colony (ABC), Selfish Herd Optimizer (SHO), Biogeography-Based Optimization (BBO), Multi-Verse Optimizer (MVO), Teaching–Learning-Based Optimization (TLBO), Cuckoo Search (CS), Moth Flame Optimization (MFO), Marine Predator Algorithm (MPA), and Flower Pollination Algorithm (FPA). Symmetric training procedures were applied across all algorithms to ensure fair and consistent evaluation. The analyses were conducted on the lowest and highest daily, weekly, and monthly Brent oil prices. Mean squared error (MSE) was used as the primary performance metric. The results showed that all algorithms achieved effective prediction performance. Among them, BBO and TLBO demonstrated superior accuracy and stability, particularly in handling the complexities of Brent oil forecasting. This study contributes to the literature by combining ANFIS and metaheuristics within a symmetric framework of experimentation and evaluation. Full article

A dual-wavelength (DW) Pr³⁺:LiLuF₄ (Pr:LLF) laser with the same threshold and slope efficiency was achieved for the first time. We theoretically deduced the conditions for obtaining the same threshold and slope efficiency of the DW operation, and experimentally demonstrated the orange-red DW Pr:LLF laser by optimizing the output coupling transmittance and adjusting the rotation angle of the intracavity Lyot filter. A CW orange-red DW laser, pumped by a 10 W 479 nm frequency-doubled optically pumped semiconductor laser (2ω-OPSL), delivers combined outputs of 607 nm and 640 nm with a total power of 2.69 W. The orange and red wavelengths maintained balanced power output under each pump level. Furthermore, by a type-I critical phase-matched (CPM) β-BaB₂O₄ (BBO) crystal, a CW ultraviolet (UV) second harmonic generation (SHG) at 312 nm was also obtained through intracavity sum-frequency mixing (SFM) of the 607 nm and 640 nm fundamental beams, achieving a maximum power output of 812 mW. Full article

The application of high-pressure jet-assisted (HPJA) machining can increase tool life during machining, as the cutting fluid penetrates better into the interfaces between the tool and the workpiece. In this work, tool life in semi-finish turning of Inconel 718 with coated carbide tools and a high-pressure coolant supply is investigated. In a preliminary experiment, tool life was compared between conventional flooding and HPJA machining. The results show tool life that is more than twice as long with HPJA at higher cutting speeds. In the main experiment, tool life was investigated as a function of various high-pressure-jet parameters (nozzle diameter, distance between the point of impact of the jet and the cutting edge and pressure of the jet) and basic cutting parameters (cutting speed and feed rate). The relationship between the above-mentioned process parameters and tool life was analyzed and modeled using response surface methodology (RSM). Analysis of variance (ANOVA) was performed to evaluate the statistical significance of each process parameter for the response. The results revealed that cutting speed is the most important factor for maximizing tool life, followed by pressure of the jet and feed rate. In addition, optimization using the biogeographic optimization (BBO) algorithm was performed and validated in this study. The results of the confirmation experiments show that the proposed optimization method is very effective and results in approximately 8.4% longer tool life compared to the best trial results. Full article

We reported on a nanosecond regenerative amplified laser with a repetition rate of 1 kHz by employing laser diodes (LDs) with distinct wavelengths as both the seed laser and the pump source and utilizing Nd:YAG as the gain medium. The single-pulse energy was 1.58 mJ and the pulse duration was adjustable, ranging from 1 to 5 ns. Combining two oppositely oriented BBO crystals for second harmonic generation (SHG) and an LBO crystal for third harmonic generation (THG), a 355 nm laser with a single-pulse energy of 257 μJ was attained, corresponding to a THG efficiency of 16.2%. Full article

The objective of this review is to investigate the effect of an additional layer of flowable composite for cavity lining on the clinical outcome of direct posterior composite restorations. The PICO question (patient, intervention, comparison, and outcome) was stated as follows: Does the additional application of a flowable composite as a cavity liner improve the clinical outcome of Class-I and Class-II restorations? The electronic databases MEDLINE, Web of Science, LILAS, and BBO were assessed for identifying relevant clinical studies. After removal of duplicate records, 309 records could be identified and, after a screening of the title and abstract, 20 articles were selected for full-text analysis. Finally, six studies met the eligibility criteria and were included in this review for further investigation. Four of the included studies have a follow-up period of two years, while the other two studies had an observation period of three and seven years, respectively. No significant differences in annual failure rates were observed between restorations with and without a flowable composite liner. Consequently, the additional usage of flowable composites as a cavity liner seems to have no effect on the clinical longevity of direct composite restorations in Class-I and Class-II cavities. Therefore, the application of a flowable composite is a possible option in everyday dental clinical practice. Full article

The science of biogeography was described through mathematical equations in 1967 by Robert MacArthur and Edward Wilson. In 2008, Dan Simon presented an algorithm called biogeography-based optimization, or BBO, which used some of the principles and definitions described in MacArthur and Wilson’s book. The objectives of this work were to study the behavior of the BBO method when it is hybridized with other evolutionary search methods and to analyze the effect of its application to some examples of mechanical engineering systems. The operators considered in the hybridization study are genetic recombination (crossover) and local search, aiming to overcome the limitations and difficulties that arise when using the original BBO. The results of the original BBO were promising in the context of a global search. However, there is a diversity problem that does not allow for good quality increments in the final phase of the evolutionary process. The additional modifications included, such as the concept of blending in migration, the cycle of mutations and the replacement of the worst solutions by injection of new ones, all show positive effects on the method’s performance. However, the biggest increase happened with the implementation of the hybridization processes. Crossover improved the speed and diversity of the population in some cases, while local search helped the algorithm in later generations, allowing it to quickly reach the optimum point. With this mentioned, it is important to note that the best results were all obtained with the fully modified algorithm. Statistical tests were implemented to validate the significance of changes due to modifications included in the original proposal of BBO. Full article

A tunable high-power 60 MHz ultraviolet pulse laser directly produced by the extra-cavity fourth-order harmonic generation of a self-similar amplification infrared pulse laser is reported in this study. Utilizing the self-similar pulse evolution and the self-phase modulation in a self-similar amplifier, the system generates a 58.9 W pulse train with a spectral half-width of 85.4 nm, corresponding to a pulse duration of 36 fs. To obtain the ultraviolet pulses from the infrared pulses, a single-pass frequency quadrupling system comprising two cascaded β-BBOs was used. The ultraviolet spectra can be tuned within a spectral range of 253.6 to 275 nm owing to the broadband infrared seed spectra. The maximum ultraviolet average power of 1.44 W was achieved at 275 nm with spectral half-width and an infrared-to-ultraviolet efficiency of 1.1 nm and 2.44%, respectively. To the best of our knowledge, this is the first demonstration of tunable high-power ultraviolet pulse generation from a self-similar amplification Yb-fiber laser. Full article

We investigate the common movement and information content of trades at steps away from the best bid and offer (BBO) using Tokyo Stock Exchange data. We create strings, a series of trades at the same or at an inferior price. The number of the strings is invariant for securities across trading days. The number of shares traded during a string and the time needed for the completion of a string are also significantly related across days for a given stock. The strings represent liquidity beyond the BBO. In addition, the strings characterize the price adjustment process in which we relate to the information on the underlying asset value. The strings measure order aggressiveness beyond the BBO. Finally, we show that the return for the strings is significantly related to the state of the limit order book at the start of the string. Thus, traders can infer information using strings to achieve higher returns. Full article

The 228 nm deep ultraviolet laser, leveraging its advantages of short wavelength, high photon energy, and low thermal effect, can significantly enhance the Raman signal in resonance Raman spectroscopy and demonstrates broad application potential in areas such as precision processing of photonic devices. This paper investigates a solid-state linear-cavity passively Q-switched 228 nm deep ultraviolet laser. Firstly, the laser employs an Nd:GdVO₄ crystal as the gain medium, combined with Cr⁴⁺:YAG crystal passive Q-switching technology to generate 912 nm pulsed fundamental frequency light. Subsequently, a lithium metaborate (LBO) crystal is used to generate 456 nm second-harmonic light, and finally, a barium metaborate (BBO) crystal is utilized to achieve 228 nm fourth-harmonic laser output. In this paper, we investigate the variation in 456 nm and 228 nm laser output power under the cavity length of 63 mm. Ultimately, at a pump power of 41.75 W, the highest average power of 670 mW was achieved for a 456 nm blue laser output with a repetition rate of 12 kHz and a pulse width of 32 ns. Additionally, a maximum average power of 18 mW was obtained for a 228 nm deep ultraviolet laser output, featuring a repetition rate of 12 kHz and a pulse width of 33 ns. Full article

Deep-ultraviolet (DUV) lasers operating at a wavelength of 228 nm offer distinct advantages in Raman spectroscopy and analysis, demonstrating significant potential in the field of surgical medicine. This paper details the development of a high-repetition-rate, narrow-pulse-width, short-cavity laser system functioning at 228.5 nm, which is based on Barium Borate (BBO) electro-optic Q-switching. The system utilizes a double-concave resonator structure and a pressure-applied electro-optic Q-switching technique, incorporating Lithium Borate (LBO) and BBO as frequency-doubling crystals. A low-concentration Nd:YVO₄ crystal, measuring 4 mm × 4 mm × 5 mm, serves as the gain medium, with a high-reflectivity coating applied to its left end face to function as the total reflection mirror within the resonant cavity. Upon achieving a pump power of 37 W at a repetition rate of 12 kHz, the system produced a maximum average power of 32 mW, with a pulse width varying from 2.48 ns to 2.70 ns and a central wavelength of 228.5 nm, which is effectively applicable for deep-ultraviolet spectral detection. Full article