Using a Modified Polyamidoamine Fluorescent Dendrimer for Capturing Environment Polluting Metal Ions Zn2+, Cd2+, and Hg2+: Synthesis and Characterizations

One of the most pressing global concerns is how to provide a clean environment for future generations given the exacerbation of urban, agricultural, industrial, and economic activities due to the escalating size of the global population. A polyamidoamine (PAMAM) dendrimer peripherally modified with 4-N,N′-dimethylethylenediamine-1,8-naphthalmide as a chromophore was synthesized and utilized to capture hazardous heavy metal ions. This modified fluorescent dendrimer (FCD) was complexed with Group 12 metal ions (Zn2+, Cd2+, and Hg2+) at a 2:1 (metal: FCD) ratio. Electronic absorption, fluorescence emission, Infra-red (IR), and nuclear magnetic resonance (1H NMR) spectroscopies, conductivity, CHN elemental, thermogravimetry, scanning electron microscopy (SEM), and transmission electron microscopy (TEM) analyses were used to characterize the resulting metal complexes. These assays revealed that the synthesized complexes were yellow-colored, thermally stable, nanoscale-sized, and composed of [M2FCD]·4Cl2. Considerable spectral shifts were observed in the emission and absorption spectra of the FCD molecule after binding the Zn2+ ions, which can be used to differentiate the Zn2+ complex from the other two complexes. This work provides basic data to facilitate the detection, quantification, and removal of environmentally hazardous heavy metal ions through complexation with a fluorescent dendrimer.

hiss, a new tool for H i stacking: application to NIBLES spectra

H i stacking has proven to be a highly effective tool to statistically analyse average H i properties for samples of galaxies which may or may not be directly detected. With the plethora of H i data expected from the various upcoming H i surveys with the SKA Precursor and Pathfinder telescopes, it will be helpful to standardize the way in which stacking analyses are conducted. In this work we present a new python-based package, hiss, designed to stack H i (emission and absorption) spectra in a consistent and reliable manner. As an example, we use hiss to study the H i content in various galaxy sub-samples from the NIBLES survey of SDSS galaxies which were selected to represent their entire range in total stellar mass without a prior colour selection. This allowed us to compare the galaxy colour to average H i content in both detected and non-detected galaxies. Our sample, with a stellar mass range of $10^8 \lt {{ M}}_\star \, (\text{M}_\odot) \lt 10^{12}$, has enabled us to probe the H i-to-stellar mass gas fraction relationship more than half an order of magnitude lower than in previous stacking studies.

Laboratory experiments on cosmic dust and ices

The existence of cosmic dust is attested by the interstellar extinction and polarization, IR emission and absorption spectra, and elemental depletion patterns. Dust grains are efficiently processed or even destroyed in shocks, molecular clouds, or protoplanetary disks. A considerable amount of dust has to be re-formed in the ISM. In various astrophysical environments, dust grains are covered by molecular ices and therefore contribute or catalytically influence the chemical reactions in these layers. Laboratory experiments are desperately required to understand the evolution of grains and grain/ice mixtures in molecular clouds and early planetary disks. This review considers recent progress in laboratory approaches to dust/ice experiments.

Erbium doped ZBLAN fiber laser operating in the visible - feasibility study

This work is focused on developing all-fiber green laser in hybrid geometry, based on combination of Er:ZBLAN active fiber and silica fiber-based passive components of optical resonator and deploying Fiber Bragg Gratings (FBGs) as highly selective mirrors for green spectral range. The scope of work covers fundamental spectroscopic characterization of Er:ZBLAN samples, determination of key spectroscopic parameters, modelling the lasing properties and lasing experiments in different pumping geometries. Full Text: PDF ReferencesW.P. Risk, T.R. Gosnell, A.V. Nurmikko, "Compact blue-green lasers", Cambridge University Press. (2003) CrossRef J.Y. Allain, M. Monerie, and H. Poignant, "Tunable green upconversion erbium fibre laser", Electronics Lett., 28 (1992) 111-113 CrossRef Z . Luo, Q. Ruan, M. Zhong, Y. Cheng, R. Yang, B. Xu, H. Xu, Z. Cai, "Compact self-Q-switched green upconversion Er:ZBLAN all-fiber laser operating at 543.4 nm", Optics Lett. 41 (2016) 2258-2261 CrossRef D. E. McCumber, "Einstein relations connecting broadband emission and absorption spectra", Physical Review 136 (1964) 954-957 CrossRef

Wastewaters Pollution Control Using Two-Frequency Laser Sounding

Optical methods for analysis of non-uniform liquid mediums have been considered, correlational and functional connections between the optical density and parameters characterizing industrial wastewaters’ type, content and pollution level have been investigated. Have been demonstrated main tendencies related to development of technology and equipment for optoelectronic control of industrial wastewaters’ pollution. Approximation of emission and absorption spectra for optical radiation’s emitter and receiver using the known Laplace function allows carry out calculations for a choice of optical couples’ coordinated parameters for two-frequency optical control, and as a result to increase reliability of identification for a type and degree of pollution for wastewaters and industrial effluents in comparison with use of one emission source. The method of pollution two-frequency laser sounding differs in improved control characteristics compared with the ones offered in patents, as well as in scientific and technical literature.