Water Quality Analysis and Recommendations through Comprehensive Pollution Index Method

Recently, the quality of surface water has become one of significant environmental planning and management issues in China. To investigate the quality of surface water, three monitoring sites, such as Majiawan Site, Huxin Site and Huguan Site, have been established by Qilu Lake, located in the north of Tonghai County, Yuxi Region, Yunnan Province, by Chinese government. In this paper, we applied comprehensive pollution index method to analyze and monitor water quality, obtained a series of determination factors which could be used to differentiate V class and Interior V class of the water quality of Qilu Lake. Accordingly, we suggest relevant recommendations from the aspects of engineering measures, chemical and biological methods

All-optical wavelength-tunable narrow-linewidth fiber laser

Parameter regulations of narrow-linewidth fiber lasers in frequency domain has drawn considerable interests for widespread applications in the light quantum computing, precise coherent detection, and generation of micro-waves. All-optical methods provide compact, precise and fast accesses to achieving these lasers with wavelength-tunability. Here, the optical-thermal effects of graphene is utilized to precisely control operations of free-running lasers with a tuning speed of 140 MHz/ms. Assisted by the single-longitude-mode operation and linewidth suppression of stimulated Brillouin backscattering, we obtain an optical-controllable ~750 Hz fiber laser with a wavelength-tuning range of 3.7 nm

A 16-step synthesis of the isoryanodane diterpene (+)-perseanol

(+)-Perseanol is an isoryanodane diterpene that is isolated from the tropical shrub Persea indica and has potent antifeedant and insecticidal properties. It is structurally related to (+)-ryanodine, which is a high-affinity ligand for and modulator of ryanodine receptors—ligand-gated ion channels that are critical for intracellular Ca^(2+) signalling in most multicellular organisms. Ryanodine itself modulates ryanodine-receptor-dependent Ca^(2+) release in many organisms, including mammals; however, preliminary data indicate that ryanodane and isoryanodane congeners that lack the pyrrole-2-carboxylate ester—such as perseanol—may have selective activity in insects. Here we report a chemical synthesis of (+)-perseanol, which proceeds in 16 steps from commercially available (R)-pulegone. The synthesis involves a two-step annulation process that rapidly assembles the tetracyclic core from readily accessible cyclopentyl building blocks. This work demonstrates how convergent fragment coupling, when combined with strategic oxidation tactics, can enable the concise synthesis of complex and highly oxidized diterpene natural products

Optical polarization rogue waves from supercontinuum generation in zero dispersion fiber pumped by dissipative soliton

Optical rogue waves emerge in nonlinear optical systems with extremely large amplitudes, and leave without a trace. In this work, we reveal the emergence of optical polarization rogue waves in supercontinuum generation from a zero-dispersion fiber, pumped by a dissipative soliton laser. Flat spectral broadening is achieved by modulation instability, followed by cascaded four-wave-mixing. In this process, we identify the emergence of optical polarization rogue waves, based on the probability density function of the relative distance among polarization states. Experimental results show that optical polarization rogue waves originate from vector multi-wave-mixing. Besides, we observe double peaks, and even triple peaks in the histogram of the state of polarization. This is a new and intriguing property, never observed so far in optical rogue waves, for example those emerging in the statistics of pulse intensities. Our polarization domain statistical analysis provides a new insight into the still debated topic of the mechanism for rogue wave generation in optical supercontinuum

Chlorido{2-[1-(2-pyridylmethyl­imino)eth­yl]pyrrolato-κ3 N,N′,N′′}copper(II)

The potential tridentate Schiff base ligand 2-[1-(2-pyridyl­methyl­imino)eth­yl]pyrrole (HL) was synthesized from the condensation of 2-acetyl­pyrrole with 2-amino­methyl­pyridine. The title compound, [Cu(C12H12N3)Cl], was synthesized from HL and copper(II) chloride using triethyl­amine as a base to deprotonate the pyrrole NH group. The title compound is a monomer and the central copper(II) ion is bound to three N atoms of the deprotonated tridentate ligand and to one chloride ion in a square-planar N3Cl coordination

Optical puff mediated laminar-turbulent polarization transition

Various physical structures exhibit a fundamentally probabilistic nature over diverse scales in space and time, to the point that the demarcation line between quantum and classic laws gets blurred. Here, we characterize the probability of intermittency in the laminar-turbulence transition of a partially mode-locked fiber laser system, whose degree of coherence is deteriorated by multiple mode mixing. Two competing processes, namely the proliferation and the decay of an optical turbulent puff, determine a critical behavior for the onset of turbulence in such a nonlinear dissipative system. A new kind of polarization rogue waves is introduced at the point of transition to polarization turbulence. The probabilistic description of the puff-mediated laminar-turbulence polarization transition provides an additional degree of freedom for our understanding of the complex physics of lasers

A 16-step synthesis of the isoryanodane diterpene (+)-perseanol

(+)-Perseanol is an isoryanodane diterpene that is isolated from the tropical shrub Persea indica and has potent antifeedant and insecticidal properties. It is structurally related to (+)-ryanodine, which is a high-affinity ligand for and modulator of ryanodine receptors—ligand-gated ion channels that are critical for intracellular Ca^(2+) signalling in most multicellular organisms. Ryanodine itself modulates ryanodine-receptor-dependent Ca^(2+) release in many organisms, including mammals; however, preliminary data indicate that ryanodane and isoryanodane congeners that lack the pyrrole-2-carboxylate ester—such as perseanol—may have selective activity in insects. Here we report a chemical synthesis of (+)-perseanol, which proceeds in 16 steps from commercially available (R)-pulegone. The synthesis involves a two-step annulation process that rapidly assembles the tetracyclic core from readily accessible cyclopentyl building blocks. This work demonstrates how convergent fragment coupling, when combined with strategic oxidation tactics, can enable the concise synthesis of complex and highly oxidized diterpene natural products