scholarly journals Impedimetric Detection of Ammonia and Low Molecular Weight Amines in the Gas Phase with Covalent Organic Frameworks

Sensors ◽  
2020 ◽  
Vol 20 (5) ◽  
pp. 1385 ◽  
Author(s):  
Andrés Rodríguez ◽  
Elio Rico ◽  
Cesar Sierra ◽  
Oscar Rodríguez
Keyword(s):  
Molecular Weight ◽  
Room Temperature ◽  
Nitrogen Adsorption ◽  
Low Molecular Weight ◽  
Covalent Organic Frameworks ◽  
X Ray Diffraction ◽  
X Ray ◽  
Ft Ir ◽  
Nitrogen Adsorption Isotherms ◽  
Significant Interference

Two Covalent Organic Frameworks (COF), named TFP-BZ and TFP-DMBZ, were synthesized using the imine condensation between 1,3,5-triformylphloroglucinol (TFP) with benzidine (BZ) or 3,3-dimethylbenzidine (DMBZ). These materials were deposited, such as films over interdigitated electrodes (IDE), by chemical bath deposition, giving rise to TFP-BZ-IDE and TFP-DMBZ-IDE systems. The synthesized COFs powders were characterized by Powder X-Ray Diffraction (PXRD), Fourier Transform Infrared spectroscopy (FT-IR), solid-state Nuclear Magnetic Resonance (ssNMR), nitrogen adsorption isotherms, Scanning Electron Microscopy (SEM), and Raman spectroscopy, while the films were characterized by SEM and Raman. Ammonia and low molecular weight amine sensing were developed with the COF film systems using the impedance electrochemical spectroscopy (EIS). Results showed that the systems TFP-BZ-IDE and TFP-DMBZ-IDE detect low molecular weight amines selectively by impedimetric analysis. Remarkably, with no significant interference by other atmospheric gas compounds such as nitrogen, carbon dioxide, and methane. Additionally, both COF films presented a range of sensitivity at low amine concentrations below two ppm at room temperature.

scholarly journals Ultrasound-Assisted Rapid ZIF-8 Synthesis, Porous ZnO Preparation by Heating ZIF-8, and Their Photocatalytic Activity

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Pham Dinh Du ◽  
Nguyen Trung Hieu ◽  
Tran Vinh Thien
Keyword(s):  
Photocatalytic Activity ◽  
Room Temperature ◽  
Diffuse Reflectance ◽  
Nitrogen Adsorption ◽  
X Ray Diffraction ◽  
Zeolitic Imidazolate Framework ◽  
X Ray ◽  
Photocatalytic Activities ◽  
Ft Ir ◽  
Adsorption Desorption

Zeolitic imidazolate framework-8 (ZIF-8) is synthesized quickly at room temperature in methanol with the support of ultrasound. Porous ZnO is also prepared via the thermal treatment of ZIF-8. The photocatalytic activities of the obtained materials are demonstrated via methylene blue (MB) decomposition under UV radiation. The obtained materials are characterized by means of X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), nitrogen adsorption/desorption isotherms, UV-Vis diffuse reflectance spectra (DR-UV-Vis), and photoluminescence spectra. The results indicate that ZIF-8 and the materials obtained from ZIF-8 by heating in the air have photocatalytic activity under UV irradiation. The ZnO sample obtained by ZIF-8 calcination at 660°C for 5 h has the highest photocatalytic activity. However, the MB degradation photocatalytic efficiency of the ZnO samples is even lower than that of the ZIF-8 samples, indicating that ZIF-8 is an effective photocatalyst in the treatment of environmental pollution.

Low Molecular Weight Microfibers with Light Sensing Properties

2017 ◽  
Vol 54 (4) ◽  
pp. 655-658
Author(s):  
Andrei Bejan ◽  
Dragos Peptanariu ◽  
Bogdan Chiricuta ◽  
Elena Bicu ◽  
Dalila Belei
Keyword(s):  
Molecular Weight ◽  
Low Molecular Weight ◽  
X Ray Diffraction ◽  
Aromatic Rings ◽  
X Ray ◽  
Force Microscopy ◽  
Light Sensing ◽  
Sensing Applications ◽  
Atomic Force ◽  
Low Molecular Weight Compounds

Microfibers were obtained from organic low molecular weight compounds based on heteroaromatic and aromatic rings connected by aliphatic spacers. The obtaining of microfibers was proved by scanning electron microscopy. The deciphering of the mechanism of microfiber formation has been elucidated by X-ray diffraction, infrared spectroscopy, and atomic force microscopy measurements. By exciting with light of different wavelength, florescence microscopy revealed a specific optical response, recommending these materials for light sensing applications.

scholarly journals Synthesis of Magnetic Ferrocene-Containing Polymer with Photothermal Effects for Rapid Degradation of Methylene Blue

Polymers ◽  
2021 ◽  
Vol 13 (4) ◽  
pp. 558
Author(s):  
Wenhui Zhu ◽  
Caiyun Zhang ◽  
Yali Chen ◽  
Qiliang Deng
Keyword(s):  
Methylene Blue ◽  
Photoelectron Spectroscopy ◽  
Room Temperature ◽  
Degradation Rate ◽  
Model Compound ◽  
Vibrating Sample Magnetometer ◽  
Simulated Sunlight ◽  
X Ray Diffraction ◽  
X Ray ◽  
Ft Ir

Photothermal materials are attracting more and more attention. In this research, we synthesized a ferrocene-containing polymer with magnetism and photothermal properties. The resulting polymer was characterized by Fourier-transform infrared (FT-IR), vibrating sample magnetometer (VSM), scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). Its photo-thermocatalytic activity was investigated by choosing methylene blue (MB) as a model compound. The degradation percent of MB under an irradiated 808 nm laser reaches 99.5% within 15 min, and the degradation rate is 0.5517 min−1, which is 145 times more than that of room temperature degradation. Under irradiation with simulated sunlight, the degradation rate is 0.0092 min−1, which is approximately 2.5 times more than that of room temperature degradation. The present study may open up a feasible route to degrade organic pollutants.

Mechanical Properties and Ordered Structure of Bacterial Poly(3-Hydroxybutyrate-Co-3-Hydroxyhexanoate) Fibers Stretched after Isothermal Crystallization near Tg

2011 ◽  
Vol 284-286 ◽  
pp. 1774-1777 ◽  
Author(s):  
Chang Kun Ding ◽  
Bo Wen Cheng ◽  
Qiong Wu
Keyword(s):  
Isothermal Crystallization ◽  
Melt Spinning ◽  
Room Temperature ◽  
Low Molecular Weight ◽  
Ordered Structure ◽  
X Ray Diffraction ◽  
Recombinant Bacteria ◽  
X Ray ◽  
Flexible Fibers ◽  
One Step

Biodegradable fibers of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBHHx) were prepared by melt spinning, followed by one-step-drawing with small crystal nuclei grown after isothermal crystallization near the glass transition temperature (Tg) and annealing at room temperature under tension. This new drawing technique is a very attractive method for obtaining flexible fibers from low-molecular-weight biopolyesters produced by recombinant bacteria. The ordered structure of PHBHHx fibers was investigated by tensile measurement, scanning electron microscopy, and wide-angle X-ray diffraction (WAXD). The tensile strength of 10 times one-step-drawn fiber after isothermal crystallization increased to 100 MPa. The WAXD profiles of PHBHHx fibers showed sharp reflections corresponding to highly oriented α-form (21helix conformation) crystal.

scholarly journals Influence of different synthesis conditions on properties of oleic acid-coated-Fe3O4 nanoparticles

2015 ◽  
Vol 33 (1) ◽  
pp. 100-106 ◽  
Author(s):  
Atieh Aliakbari ◽  
Majid Seifi ◽  
Sharareh Mirzaee ◽  
Hoda Hekmatara
Keyword(s):  
Oleic Acid ◽  
Room Temperature ◽  
Magnetic Measurement ◽  
Precursor Solution ◽  
Vibrating Sample Magnetometer ◽  
X Ray Diffraction ◽  
X Ray ◽  
Synthesis Conditions ◽  
Transmission Electron ◽  
Ft Ir

AbstractIn the present paper, iron oxide nanoparticles coated by oleic acid have been synthesized in different conditions by coprecipitation method. For investigating the effect of time spent on adding the oleic acid to the precursor solution, two different processes have been considered. The as synthesized samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and Fourier transform infrared spectroscopy (FT-IR). Magnetic measurement was carried out at room temperature using a vibrating sample magnetometer (VSM). The results show that the magnetic nanoparticles decorated with oleic acid decreased the saturation of magnetization. From the data, it can also be concluded that the magnetization of Fe3O4/oleic acid nanoparticles depends on synthesis conditions.

scholarly journals Hydrogels formed from Fmoc amino acids

CrystEngComm ◽  
2015 ◽  
Vol 17 (42) ◽  
pp. 8047-8057 ◽  
Author(s):  
Emily R. Draper ◽  
Kyle L. Morris ◽  
Marc A. Little ◽  
Jaclyn Raeburn ◽  
Catherine Colquhoun ◽  
...  
Keyword(s):  
Amino Acids ◽  
Molecular Weight ◽  
Single Crystal ◽  
Crystal Structures ◽  
Diffraction Data ◽  
Low Molecular Weight ◽  
X Ray Diffraction ◽  
X Ray ◽  
Single Crystal Structures

A number of Fmoc amino acids can be effective low molecular weight hydrogelators; we compare single crystal structures to fibre X-ray diffraction data.

scholarly journals A Simple and Facile Solvothermal Synthesis of Hierarchical PbS Microstars with Multidendritic Arms and Their Optical Properties

2015 ◽  
Vol 2015 ◽  
pp. 1-9 ◽  
Author(s):  
Yong-Fang Li ◽  
Ming Zhang ◽  
Qi-Jing Yang ◽  
Feng-Xian Zhang ◽  
Mei-Qi Zheng ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Solvothermal Synthesis ◽  
Room Temperature ◽  
X Ray Diffraction ◽  
X Ray ◽  
Practical Applications ◽  
Solar Absorbers ◽  
Transmission Electron ◽  
Ir Photodetectors ◽  
Ft Ir

A simple and facile approach was developed in the solvothermal synthesis of hierarchical PbS microstars with multidendritic arms, which were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fourier transform infrared (FT-IR) and photoluminescence (PL) spectroscopy. The morphologies of PbS products were strongly determined by the reaction time and temperature, the ratios of the precursors, and the mixed solvent with various components, and thereby their possible formation mechanism was discussed in some detail. The as-prepared PbS crystals displayed a sharp and strong photoluminescent peak at 437 nm at room temperature. It has potential and practical applications in photoluminescence, photovoltaics, IR photodetectors, electroluminescence, and solar absorbers.

Preparation of Strontium Ferrite Powders by Mechanochemical Process

2011 ◽  
Vol 110-116 ◽  
pp. 1736-1740 ◽  
Author(s):  
Ju Hua Luo
Keyword(s):  
Magnetic Properties ◽  
Room Temperature ◽  
Single Phase ◽  
Raw Materials ◽  
X Ray Diffraction ◽  
X Ray ◽  
Starting Mixture ◽  
Ft Ir ◽  
Mechanochemical Treatments ◽  
Firing Method

Sr-ferrite powders were preparated by mechanochemical treatments using SrCO3 and Fe2O3 as raw materials. Scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), vibrating sample magnetometry (VSM) were employed to evaluated the morphologies, structures and magnetic properties of samples. The results indicated that the starting mixture became amorphous stage after ball-milled for 30h, and single phase SrFe12O19 could be obtained after annealed at 900°C for 2h. And the saturation magnetization was 58.2Am2/kg, and coercivity was 281.2 kA/m at room temperature. In comparison with the traditional firing method , the mechanochemical method benefited achieving the higher coercivity, which indicated that the samples had a better magnetic properties.

Polyethersulfone polymers and oligomers — Morphology and crystallization

2012 ◽  
Vol 90 (10) ◽  
pp. 880-890 ◽  
Author(s):  
Abdelkader Benhalima ◽  
François Hudon ◽  
Finda Koulibaly ◽  
Christian Tessier ◽  
Josée Brisson
Keyword(s):  
Molecular Weight ◽  
Model Compound ◽  
Crystal Form ◽  
Low Molecular Weight ◽  
Structural Studies ◽  
X Ray Diffraction ◽  
Crystal Forms ◽  
X Ray ◽  
Diphenyl Sulfone ◽  
Induced Crystallization

Crystal forms of polyethersulfones (PES) were investigated by using a model compound and a low molecular weight oligomer. These are amorphous as-synthesized, and can undergo solvent-induced crystallization under the appropriate conditions. The model compound, 4,4′-bis(p-methoxyphenoxy)diphenyl sulfone, yielded monocrystals, and its structure was solved using X-ray diffraction. Conformational disorder is present, two conformers cohabiting in 55:45 proportions. This model compound, combined to previous structural studies published in the literature, served as a basis for conformational studies of polyethersulfone. Low molecular weight polymers submitted to solvent-induced crystallization resulted in a PES crystal form different from that previously published in the literature, as shown by powder X-ray diffraction.

scholarly journals Characterization of the structure and composition of gecko adhesive setae

2005 ◽  
Vol 3 (8) ◽  
pp. 441-451 ◽  
Author(s):  
N.W Rizzo ◽  
K.H Gardner ◽  
D.J Walls ◽  
N.M Keiper-Hrynko ◽  
T.S Ganzke ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Molecular Weight ◽  
Electrophoretic Analysis ◽  
Low Molecular Weight ◽  
X Ray Diffraction ◽  
X Ray ◽  
Pattern Characteristic ◽  
Additional Protein ◽  
Adhesive Materials

The ability of certain reptiles to adhere to vertical (and hang from horizontal) surfaces has been attributed to the presence of specialized adhesive setae on their feet. Structural and compositional studies of such adhesive setae will contribute significantly towards the design of biomimetic fibrillar adhesive materials. The results of electron microscopy analyses of the structure of such setae are presented, indicating their formation from aggregates of proteinaceous fibrils held together by a matrix and potentially surrounded by a limiting proteinaceous sheath. Microbeam X-ray diffraction analysis has shown conclusively that the only ordered protein constituent in these structures exhibits a diffraction pattern characteristic of β-keratin. Raman microscopy of individual setae, however, clearly shows the presence of additional protein constituents, some of which may be identified as α-keratins. Electrophoretic analysis of solubilized setal proteins supports these conclusions, indicating the presence of a group of low-molecular-weight β-keratins (14–20 kDa), together with α-keratins, and this interpretation is supported by immunological analyses.

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