Hollow-Core Fiber: Breaking the Nonlinearity Limits of Silica Fiber in Long-Distance Green Laser Pulse Delivery

Hollow-core fiber (HCF), in which >99.99% of the light is guided in a central air (or vacuum) filled core, is a radically new fiber technology offering the potential to overcome the nonlinear limits associated with the delivery of high-brightness laser pulses over long distances in conventional solid-core fiber. Overcoming these limits is particularly challenging at visible wavelengths where the core sizes of single-mode fibers (SMFs) are reduced. In this work, the delivery of near-diffraction-limited, kilowatt-peak-power, sub-nanosecond laser pulses in the green wavelength range over hundred-meter scale lengths of a hollow-core anti-resonant fiber (HC-ARF) which offers broadband low-loss guidance in the visible is experimentally demonstrated. Substantially reduced nonlinearity-induced spectral broadening is observed relative to silica-core SMF. The simulation further confirms that the broadening observed (in the HC-ARF) is entirely due to the interaction of the light with the air in the core and thus can effectively be eliminated by evacuating the fiber. Moreover, access to lower-loss is noted, and visible guiding HC-ARFs (that are now becoming available) will improve the throughput efficiency and extend power delivery to kilometer distance scales. The results demonstrated here pave the way for future long-distance HCF pulse delivery applications, such as remote industrial e-mobility manufacturing.     

Synthesis of 2H-thiochromene derivatives (microreview)

Chemistry of Heterocyclic Compounds - The microreview considers recent methodologies for the synthesis of 2H-thiochromenes including enantioselective synthesis, multistep synthesis,...     

Novel (thio)barbituric-phenoxy-N-phenylacetamide derivatives as potent urease inhibitors: synthesis,in vitro urease inhibition,and in silico evaluations

Structural Chemistry - A novel series of (thio)barbituric-phenoxy-N-phenylacetamide derivatives 7a-l was synthesized and evaluated against Helicobacter pylori urease. The latter assay revealed that...     

Pyridine-2-yl Quinoxaline (2-CPQ) Derivative As a Novel Pink Fluorophore: Synthesis,and Chemiluminescence Characteristics

Quinoxaline derivatives are well-known N-heterocycles with pharmacological and fluorescence activities. Almost all quinoxaline derivatives with extensive π-conjugation have been introduced as fluorophores which emit blue and green light. For the first time, we designed and synthesized 6-chloro-2,3 di(Pyridine-2yl) quinoxaline (2-CPQ) as a pink fluorophore in acetonitrile medium by simple route at room temperature whitin 30 min. The synthesized quinoxaline was identified using ¹H, ¹³C NMR, MS, and FT-IR spectroscopy. Our results showed that the iodine-catalyzed method for both oxidation and cyclization during the synthesis of quinoxaline from pyridine 2-carbaldehyde was straightforward, efficient, and clean. All of the mentioned characterization devices confirmed the synthesis of 2-CPQ.

Moreover, we studied the photophysical properties of the synthesized fluorophore in which The UV–Vis absorption spectrum of 2-CPQ in DMF were three peaks at 451, 518 and 556 nm. Based on photophysical properties investigation, 2-CPQ shows good fluorescence with maximum peaks 607 and 653 nm in DMF as solvent (ф_F?=?0.21). Hence, the fluorophore was applied in the peroxyoxalate chemiluminescence system. The reaction of imidazole, H₂O_2, and bis (2,4,6-trichlorophenyl) oxalate (TCPO) can transfer energy to a 6-chloro-2,3 di(pyridine-2yl) quinoxaline. In this process, dioxetane was synthesized, which chemically initiated the electron exchange luminescence (CIEEL) mechanism and led to pink light emission. We anticipate our synthesized fluorophores 2-CPQ will have great potential applications in imaging and medical markers.

     

Radiological impact assessment and dose distribution pattern in gorgan bay,Northern Iran

Journal of Radioanalytical and Nuclear Chemistry - In this study, the specific activity of radionuclides was measured using a high purity germanium detector (HPGe) and the distribution pattern of...     

Random variables and integral logic

We study model theory of random variables using finitary integral logic. We prove definability of some probability concepts such as having F(u) as distribution function, independence and martingale property. We then deduce Kolmogorov's existence theorem from the compactness theorem.     

Transient analysis of thermo-elastic waves in thick hollow cylinders using a stochastic hybrid numerical method,considering Gaussian mechanical properties

This article attempts to study the stochastic coupled thermo-elasticity of thick hollow cylinders subjected to thermal shock loading considering uncertainty in mechanical properties. The thermo-elastic governing equations based on Green–Naghdi theory (without energy dissipation) are stochastically solved using a hybrid numerical method (combined Galerkin finite element and Newmark finite difference methods). The mechanical properties are considered as random variables with Gaussian distribution, which are generated using Monte Carlo simulation method with various coefficients of variations (COVs). The effects of uncertainty in mechanical properties with various coefficients of variations on thermo-elastic wave propagation are studied in detail. Also, the maximum, mean and variance of temperature, displacement and stresses are illustrated across thickness of cylinder in various times.