Low repetition rate 915†nm figure-9 ultrafast laser with all-fiber structure.

The advent of optical metrology applications has necessitated the development of compact, reliable, and cost-effective picosecond lasers operating around 900 nm, specifically catering to the requirements of precise ranging. In response to this demand, our work introduces an innovative solution-an all-fiber, all-polarization-maintaining (PM) figure-9 mode-locked laser operating at 915 nm. The proposed figure-9 Nd-doped fiber laser has a 69.2 m long cavity length, strategically designed and optimized to yield pulses with a combination of high pulse energy and low repetition rate. The laser can generate 915 nm laser pulses with a pulse energy of 4.65 nJ, a pulse duration of 15.2 ps under the repetition rate of 3.05 MHz. The 1064 nm amplified spontaneous emission (ASE) is deliberately filtered out, in order to prevent parasitic lasing and increase the spectral proportion of the 915 nm laser. The all-PM fiber configuration of this laser imparts exceptional mode-locking performance and environmental robustness, which is confirmed by long-term output power and spectral stability test. This compact and long-term reliable fiber laser could be a promising light source for applications like inter-satellite ranging.

Generation of 1.3†µm femtosecond pulses by cascaded nonlinear optical gain modulation in phosphosilicate fiber.

Nonlinear optical gain modulation (NOGM) is a simple and effective approach to generate highly coherent ultrafast pulses with a flexible wavelength. In this work, we demonstrate 34 nJ, 170 fs pulse generation at 1319 nm through a piece of phosphorus-doped fiber by two-stage cascaded NOGM with a 1064 nm pulsed pump. Beyond the experiment, numerical results show that 668 nJ, 391 fs pulses at 1.3 µm can be produced with up to 67% conversion efficiency by increasing the pump pulse energy and optimizing the pump pulse duration. This would offer an efficient method to obtain high-energy sub-picosecond laser sources for applications such as multiphoton microscopy.

Generation of 978†nm dispersion-managed solitons from a polarization-maintaining Yb-doped figure-of-9 fiber laser.

Restricted by the narrow gain bandwidth of Yb3+ near 980 nm, it is challenging to generate dispersion-managed (DM) solitons at this wavelength. In this work, we demonstrate the generation of DM solitons at 978 nm in a polarization-maintaining (PM) figure-of-9 fiber laser. Highly coherent pulses with 14.4 nm spectral bandwidth and 175 fs pulse duration are experimentally obtained. To the best of our knowledge, this is the shortest ∼980 nm pulse ever reported in an Yb-doped mode-locked fiber laser. Numerical simulations are performed to reveal the DM solitons' temporal and spectral evolution inside the figure-of-9 cavity under the condition of a narrow gain bandwidth. This robust and cost-effective 978 nm femtosecond laser is a promising light source for applications such as underwater communication and biophotonics.

Neospora caninum seroprevalence in water buffaloes in Guangxi, China.

Neospora caninum is an important obligate intracellular apicomplexan parasite that causes spontaneous abortions in cattle and leads to huge economic losses to the farming industry. Although a high prevalence of N. caninum infection has been reported in Asia, data on the prevalence of water buffaloes in China remain unclear. To understand the seroprevalence of N. caninum infection in water buffaloes and its definitive host dogs in China, a total of 987 water buffalo sera from Guangxi Province were tested using an indirect enzyme-linked immunosorbent assay. We obtained an overall seroprevalence of 50.9% (502/987) for water buffalo samples. And the positive rate was higher in border cities (56.8%, 425/748) than in central cities (32.3%, 77/239). We further tested 240 serum samples from dogs in Guangxi and found an overall prevalence of 57.9% (139/240). The high prevalence of N. caninum infection in both dogs and water buffaloes was first reported in southern China, and these data will surely contribute to the prevention and control of the disease.

Seroprevalence of Toxoplasma gondii in water buffaloes and cats in Guangxi, China.

Toxoplasma gondii is a pathogen that poses a serious threat to human health and causes significant economic losses to the global livestock industry. The prevalence of toxoplasmosis infection has been reported to be high in humans and animals around the world, but the occurrence of the disease has not yet been reported in water buffaloes in Guangxi Zhuang Autonomous Region, southern China. To understand the overall seroprevalence of T. gondii infection in Guangxi, a total of 1041 water buffalo and 114 cat serum samples were examined using an indirect enzyme-linked immunosorbent assay (I-ELISA). Of the 1041 water buffaloes analyzed, an overall seroprevalence of 52.9% (551/1041) was obtained, with year, season, and city location being significant factors affecting the rate of T. gondii infection in water buffaloes (P < 0.001). The results also revealed a high seroprevalence of 57% (65/114) in cats. Given that buffalo milk and meat products are vital food sources, these findings suggest that toxoplasmosis in water buffaloes may be a public health threat. This study provides the first T. gondii seroprevalence data in Guangxi, which could contribute to the prevention and control of toxoplasmosis in the region.

Numerical simulation of nonlinear optical gain modulation in a Raman fiber amplifier.

Nonlinear optical gain modulation (NOGM) in a Raman fiber amplifier is numerically simulated with the generalized nonlinear Schrödinger equation. In the NOGM setup, a single frequency continuous wave seed laser is gain modulated into femtosecond pulses by an ultrafast pump, which can induce strong stimulated Raman scattering in a piece of single mode optical fiber. Different parameters regarding seed, pump and nonlinear gain medium (Raman fiber) are investigated in detail to find the best condition for higher Raman conversion efficiency. Simulated results reveal that the walk-off between pump and Raman pulses due to dispersion is one of the most important factors affecting the NOGM pulse's performance. Only when the speed of walk-off matches with the one of Raman conversion process can the conversion efficiency be optimized. This work offers a guild-line for the design of a fiber-based NOGM laser, which is able to produce wavelength-agile, femtosecond laser pulses with µJ-level pulse energy under more than 85% efficiency.

Cascaded nonlinear optical gain modulation for coherent femtosecond pulse generation.

Nonlinear optical gain modulation (NOGM) is a method to generate high performance ultrafast pulses with wavelength versatility. Here we demonstrate coherent femtosecond Raman pulse generation through cascaded NOGM process experimentally. Two single-frequency seed lasers (1121 and 1178 nm) are gain-modulated by 117 nJ 1064 nm picosecond pulses in a Raman fiber amplifier. Second-order (1178 nm) Stokes pulses are generated, which have a pulse energy of 76 nJ (corresponding to an optical conversion efficiency of 65%) with a pulse duration of 621 fs (after compression). Dynamic evolution of both pump and cascaded Stokes pulses within the Raman amplifier are investigated by numerical simulations. The influences of pump pulse duration and energy are studied in detail numerically. Moreover, the simulations reveal that NOGM pulses with higher energy and shorter pulse duration could be obtained by limiting the impact of walk-off effect between pump and Raman pulses. This approach can offer a high energy and wavelength-agile ultrafast source for various applications such as optical metrology and biomedical imagining.

In Vitro and In Vivo Activities of Tilmicosin and Acetylisovaleryltylosin Tartrate against Toxoplasma gondii.

Toxoplasma gondii is a widespread intracellular pathogen that infects humans and a variety of animals. The current therapeutic strategy for human toxoplasmosis is a combination of sulphadiazine and pyrimethamine. However, this combination still has a high failure rate and is ineffective against chronic infections. Therefore, it is important to discover a new anti-T. gondii drug that is safer and more effective in both humans and animals. In this study, we describe the anti-T. gondii activities of the 16-membered macrolide tilmicosin and acetylisovaleryltylosin tartrate (ATLL). Both tilmicosin and ATLL potently inhibited T. gondii with a half-maximal effective concentration (EC50) of 17.96 µM and 10.67 µM, respectively. Interestingly, tilmicosin and ATLL had different effects on the parasites. ATLL exhibited a potent inhibitory effect on intracellular parasite growth, while tilmicosin suppressed parasites extracellularly. By studying the lytic cycle of T. gondii after treatment, we found that ATLL potently inhibited the intracellular proliferation of tachyzoites, while tilmicosin affected the invasion of tachyzoites. Immunofluorescence analysis using ATLL-treated T. gondii showed morphologically abnormal parasites, which may be due to the inhibition of tachyzoite proliferation and division. In addition, tilmicosin and ATLL significantly delayed the death of mice caused by acute toxoplasmosis. Our results suggest that ATLL has potent anti-Toxoplasma activity both in vitro and in vivo and may be an alternative to toxoplasmosis in the future.

Evaluation of the Combined Effect of Artemisinin and Ferroptosis Inducer RSL3 against Toxoplasma gondii.

Toxoplasma gondii is a widespread intracellular pathogen that infects humans and a variety of animals. Dihydroartemisinin (DHA), an effective anti-malarial drug, has potential anti-T. gondii activity that induces ferroptosis in tumor cells, but the mechanism by which it kills T. gondii is not fully understood. In this study, the mechanism of DHA inhibiting T. gondii growth and its possible drug combinations are described. DHA potently inhibited T. gondii with a half-maximal effective concentration (EC50) of 0.22 µM. DHA significantly increased the ROS level of parasites and decreased the mitochondrial membrane potential, which could be reversed by ferroptosis inhibitors (DFO). Moreover, the ferroptosis inducer RSL3 inhibited T. gondii with an EC50 of 0.75 µM. In addition, RSL3 enhanced the DHA-induced ROS level, and the combination of DHA and RSL3 significantly increased the anti-Toxoplasma effect as compared to DHA alone. In summary, we found that DHA-induced ROS accumulation in tachyzoites may be an important cause of T. gondii growth inhibition. Furthermore, we found that the combination of DHA and RSL3 may be an alternative to toxoplasmosis. These results will provide a new strategy for anti-Toxoplasma drug screening and clinical medication guidance.

Effect of pH on the soybean whey protein-gum arabic emulsion delivery systems for curcumin: Emulsifying, stability, and digestive properties.

A novel curcumin (CUR) delivery system was developed using soybean whey protein (SWP)-based emulsions, enhanced by pH-adjustment and gum arabic (GA) modification. Modulating electrostatic interactions between SWP and GA at oil/water interface, pH provides favorable charging conditions for stable distribution between droplets. GA facilitated the SWP form a stable interfacial layer that significantly enhanced the emulsifying properties and CUR encapsulation efficiency of the system at pH 6.0, which were 90.15 ± 0.67%, 870.53 ± 3.22 m2/g and 2157.62 ± 115.31%, respectively. Duncan's test revealed significant improvements in thermal, UV, oxidative, and storage stabilities of CUR (P < 0.05). At pH 6.0, GA effectively protected CUR by inhibiting SWP degradation during gastric digestion and promoting the release of CUR by decreasing steric hindrance with oil droplets during intestinal digestion, achieving the highest CUR bioaccessibility (69.12% ± 0.28%) based on Duncan's test. The SWP-GA-CUR emulsion delivery system would be a novel carrier for nutrients.

Liposomes decorated with ß-conglycinin and glycinin: Construction, structure and in vitro digestive stability.

Liposomes were modified with different proportions of ß-conglycinin (7S) and glycinin (11S) to form Lip-7S and Lip-11S. The morphology, interaction and in vitro simulated digestion of liposomes were studied. The particle size of Lip-7S was smaller than that of Lip-11S. When the values of Lip-7S and Lip-11S were 1:1 and 1:0.75, respectively, the ζ-potential had the maximum absolute value and the dispersion of the system was good. The results of multispectral analysis showed that hydrogen-bond and hydrophobic interaction dominated protein-modified liposomes, the protein structure adsorbed on the surface of liposomes changed, the content of α-helix decreased, and the structure of protein-modified liposomes became denser. The surface hydrophobicity and micropolarity of liposomes decreased with the increase of protein ratio, and tended to be stable after Lip-7S (1:1) and Lip-11S (1:0.75). Differential scanning calorimetry showed that Lip-7S had higher phase transition temperature (≥170.5 °C) and better rigid structure. During simulated digestion, Lip-7S (22.5 %) released less Morin than Lip (40.6 %) and Lip-11S (26.2 %), and effectively delayed the release of FFAs. The environmental stability of liposomes was effectively improved by protein modification, and 7S had better modification effect than 11S. This provides a theoretical basis for 7S and 11S modified liposomes, and also provides a data reference for searching for new materials for stabilization of liposomes.

Heterogeneous nucleation induced A. pernyi/B. mori silk fibroin coatings on AZ31 biometals with enhanced corrosion resistance, adhesion and biocompatibility.

Silk fibroin coatings on biomedical magnesium alloys have garnered significant attention due to their enhanced corrosion resistance and biocompatibility. However, the utilization of wild A. pernyi silk fibroin, known for its RGD sequence that facilitates tissue regeneration, presents a challenge for corrosion-resistant coatings on magnesium alloys due to its weak adhesion and high dissolution rate. In this study, we employed hexafluoroisopropanol as a solvent to blend A. pernyi silk fibroin with B. mori silk fibroin. The resulting blended fibroin coating at a 3:7 mass ratio exhibited a heterogeneous nucleation effect, enhancing ß-sheet content (32.3 %) and crystallinity (28.6 %). This improved ß-sheet promoted the "labyrinth effect" with an Icorr of 2.15 × 10-6 A cm-2, resulting in significantly improved corrosion resistance, which is two orders of magnitude lower than that of pure magnesium alloy. Meanwhile, the increased content of exposed serine in zigzag ß-sheet contributes to a higher adhesion strength. Cell cytotoxicity evaluation confirmed the enhanced cell adhesion and bioactivity. This work provides a facile approach for wild A. pernyi silk fibroin coatings on magnesium alloys with enhanced corrosion resistance, adhesion and biocompatibility.

In vitro anti-Toxoplasma gondii effects of a coccidiostat dinitolmide.

Coccidiosis, caused by Eimeria species, results in huge economic losses to the animal industry. Dinitolmide, a veterinary-approved coccidiostat, has a wide anticoccidial spectrum with no effect on host immunity. However, the mechanism of its anticoccidial effects remains unclear. Here, we used an in vitro culture system of T. gondii to explore the anti-Toxoplasma effect of dinitolmide and its underlying mechanism against coccidia. We show that dinitolmide has potent in vitro anti-Toxoplasma activity with the half-maximal effective concentration (EC50) of 3.625 µg/ml. Dinitolmide treatment significantly inhibited the viability, invasion and proliferation of T. gondii tachyzoites. The recovery experiment showed that dinitolmide can completely kill T. gondii tachyzoites after 24 h of treatment. Morphologically abnormal parasites were observed after dinitolmide exposure, including asynchronous development of daughter cells and deficiency of parasite inner and outer membrane. Further electron microscopy results showed that the drug could damage the membrane structure of T. gondii. By comparative transcriptomic analysis, we found that genes related to cell apoptosis and nitric-oxide synthase were up-regulated after dinitolmide treatment, which might be responsible for parasite cell death. Meanwhile, many Sag-related sequence (srs) genes were down-regulated after treatment, which could be closely associated with the reduction of parasite invasion and proliferation capacity. Our study indicates that the coccidiostat dinitolmide has a potent inhibitory effect on T. gondii in vitro and provides insight into the mode of action of the drug.

Soy Protein Isolate/Sodium Alginate Microparticles under Different pH Conditions: Formation Mechanism and Physicochemical Properties.

The effects of sodium alginate (SA) and pH value on the formation, structural properties, microscopic morphology, and physicochemical properties of soybean protein isolate (SPI)/SA microparticles were investigated. The results of ζ-potential and free sulfhydryl (SH) content showed electrostatic interactions between SPI and SA, which promoted the conversion of free SH into disulfide bonds within the protein. The surface hydrophobicity, fluorescence spectra, and Fourier transform infrared spectroscopy data suggested that the secondary structure and microenvironment of the internal hydrophobic groups of the protein in the SPI/SA microparticles were changed. Compared with SPI microparticles, the surface of SPI/SA microparticles was smoother, the degree of collapse was reduced, and the thermal stability was improved. In addition, under the condition of pH 9.0, the average particle size of SPI/SA microparticles was only 15.92 ± 0.66 µm, and the distribution was uniform. Rheological tests indicated that SA significantly increased the apparent viscosity of SPI/SA microparticles at pH 9.0. The maximum protein solubility (67.32%), foaming ability (91.53 ± 1.12%), and emulsion activity (200.29 ± 3.38 m2/g) of SPI/SA microparticles occurred at pH 9.0. The application of SPI/SA microparticles as ingredients in high-protein foods is expected to be of great significance in the food industry.

Two ferritin genes (MdFerH and MdFerL) are involved in iron homeostasis, antioxidation and immune defense in housefly Musca domestica.

Ferritin is a ubiquitous multi-subunit iron storage protein, made up of heavy chain and light chain subunits. In recent years, invertebrate ferritins have emerged as an important, yet largely underappreciated, component of host defense and antioxidant system. Here, two alternatively spliced transcripts encoding for a unique ferritin heavy chain homolog (MdFerH), and a transcript encoding for a light chain homolog (MdFerL) are cloned and characterized from Musca domestica. Comparing with MdFerH1, a fragment is absent at the 5' untranslated region of MdFerH2, where a putative iron response element is present. Amino acid sequence analysis shows that MdFerH possesses a strictly conserved ferroxidase site, while MdFerL has a putative atypical active center. Tissue distribution analysis indicates that MdFers are enriched expressed in gut. When the larvae receive diverse stimulations, including challenge by bacteria, exposure to excess Fe2+, doxorubicin or ultraviolet, the expression of MdFers is positively up-regulated in different degrees and different temporal patterns, indicating their potential roles in oxidative stress. The two mRNA isoforms of MdFerH appear to be differentially expressed in different tissues, but seem to show the similar expression patterns under diverse stress conditions. Further investigation reveals that silencing MdFers can alter the redox homeostasis, leading elevated mortalities of larvae following bacterial infection. Inspiringly, recombinant MdFerL produced in Pichia pastoris shows significant iron-chelating activity in vitro. These results suggest a pivotal role of ferritins from housefly in iron homeostasis, antibacterial immunity and redox balance.

Lorf9 deletion significantly eliminated lymphoid organ atrophy induced by meq-deleted very virulent Marek's disease virus.

Marek's disease virus (MDV) is a highly contagious alphaherpesvirus that causes rapid onset of T cell lymphomas in chickens. MDV continues to break through vaccinal immunity due to the emergence of highly virulent field strains. Earlier studies revealed that deletion of the meq gene from MDV results in attenuated vaccines that protect against disease when chickens are infected with highly virulent strains. However, meq-deleted viruses still retain the ability to induce lymphoid organ atrophy, which raises safety concerns. In an earlier study, we found that deletion of lorf9 counteracts this lymphoid organ atrophy. Here, we describe the generation of a double deletion mutant virus lacking virus-encoded meq and lorf9. In vitro studies revealed that during replication, the mutant virus had kinetic characteristics similar to the parental virus; however, in vivo the replication capability was significantly reduced. Results of animal studies revealed no obvious MDV-specific symptoms and lesions. Importantly, the double deletion mutant virus lost the capacity to induce lymphoid organ atrophy, which has been the main obstacle during development of a good vaccine candidate.