scholarly journals Coaxial μSAXS/POM simultaneous measurement for microstructural characterization of one-dimensional and two-dimensional crystalline polymer

2021 ◽  
pp. 107461
Author(s):  
Yunyi Fan ◽  
Guangfeng Liu ◽  
Xiaran Miao ◽  
Fenggang Bian
Keyword(s):  
Simultaneous Measurement ◽  
Microstructural Characterization ◽  
Crystalline Polymer ◽  
Two Dimensional ◽  
One Dimensional

scholarly journals SEM characterization of two-dimensional patterns generated in titanium by femtosecond laser interferometry

2013 ◽  
Vol 19 (S4) ◽  
pp. 143-144
Author(s):  
V. Oliveira ◽  
N.I. Polushkin ◽  
O. Conde ◽  
R. Vilar
Keyword(s):  
Laser Radiation ◽  
Femtosecond Laser ◽  
Repetition Rate ◽  
Pulse Repetition Rate ◽  
Two Dimensional ◽  
Femtosecond Laser Radiation ◽  
Scanning Velocity ◽  
One Dimensional ◽  
Scanning Electron

Laser ablation using ultrafast femtosecond lasers and holographic schemes has proven to be a powerful and versatile tool for surface and volume structuring. The principle of operation of this technique is simple: when two or more pulses overlap in time and space, an interference pattern is generated that can be used to create periodic surface structures. In addition, due to the extremely short pulse duration, a very high peak power is achieved leading to intense non-linear effects. As a result, almost any type of material can be processed without undesirable collateral thermal effects.In this paper, characterization of two-dimensional (2D) patterns generated in titanium using femtosecond laser radiation has been carried out using scanning electron microscopy (SEM). The laser source is a commercial Yb:KYW laser system providing pulses with a duration of 560 fs at a central wavelength of >= 1030 nm. The surface topography was characterized using a Hitachi S2400 scanning electron microscope operated at an electron acceleration voltage of 25.0 kV. Laser processing was performed in air on polished grade 2 titanium samples, a material typically used in low load bearing medical devices.One-dimensional (1D) gratings were created using a modified Michelson interferometer described in detail elsewhere (Oliveira et al., 2012). To create 2D gratings a double exposure method was used. First, 1D gratings were produced in linear tracks by translating the sample relatively to the stationary interfering laser beams with a fixed scanning velocity of 0.1 mm/s. As an example, Figure 1 depicts SEM pictures of horizontal and vertical 1D gratings with period of about 3.9 m, generated using a pulse energy and pulse repetition rate of 0.35 mJ and 100 Hz, respectively. The peak to valley distance of these patterns can be controlled either by changing the scanning velocity or the pulse repetition rate. By overlapping two linear tracks, different kinds of 2D structures can be created. Figure 2 depicts a square pattern obtained by overlapping two 1D gratings rotated by 90°. The dimensions of the squares depend on the one-dimensional gratings period, which in turn can be easily controlled by varying the distance between the interfering beams. Figure 3 depicts two other possibilities: i) trapezium-like patterns obtained by rotating the 1D gratings by 45°, and ii) rectangular patterns obtained using 1D gratings with different periods and rotated by 90°.The proposed optical setup offers a simple method of texturing the surface of materials and, hence, to control surface properties such as wettability. In the case of titanium, this is particularly important because surface texturing enhances its osseointegration ability. For this purpose, when compared with the columns spontaneously formed on titanium surfaces treated with femtosecond laser radiation, these 2D gratings present the major advantage of being size and shape-controllable.

One- and two-dimensional PbII compounds resulting from reaction of PbBr2 and Pb(SCN)2 with pyrimidine-2-thione

2021 ◽  
Vol 77 (7) ◽  
Author(s):  
Vânia Denise Schwade ◽  
Bárbara Tirloni
Keyword(s):  
Structural Characterization ◽  
Diffuse Reflectance ◽  
Tautomeric Form ◽  
Two Dimensional ◽  
X Ray Diffraction ◽  
One Dimensional ◽  
X Ray ◽  
Ft Ir ◽  
Compound Ii

Pyrimidine-2-thione (HSpym) reacts with lead(II) thiocyanate and lead(II) bromide in N,N-dimethylformamide (DMF) to form poly[(μ-isothiocyanato-κ2 N:S)(μ4-pyrimidine-2-thiolato-κ6 N 1,S:S:S:S,N 3)lead(II)], [Pb(C4H3N2S)(NCS)] n or [Pb(Spym)(NCS)] n , (I), and the polymeric one-dimensional (1D) compound catena-poly[[μ4-bromido-di-μ-bromido-(μ-pyrimidine-2-thiolato-κ3 N 1,S:S)(μ-pyrimidine-2-thione-κ3 N 1,S:S)dilead(II)] N,N-dimethylformamide monosolvate], {[Pb2Br3(C4H3N2S)(C4H4N2S)]·C3H7NO} n or {[Pb2Br3(Spym)(HSpym)]·DMF} n , (IIa), respectively. Poly[μ4-bromido-di-μ3-bromido-(μ-pyrimidine-2-thiolato-κ3 N 1,S:S)(μ-pyrimidine-2-thione-κ3 N 1,S:S)dilead(II)], [Pb2Br3(C4H3N2S)(C4H4N2S)] n or [Pb2Br3(Spym)(HSpym)] n , (IIb), could be obtained as a mixture with (IIa) when using a lesser amount of solvent. In the crystal structures of the pseudohalide/halide PbII stable compounds, coordination of anionic and neutral HSpym has been observed. Both Spym− (in the thiolate tautomeric form) and NCS− ligands were responsible for the two-dimensional (2D) arrangement in (I). The Br− ligands establish the 1D polymeric arrangement in (IIa). Eight-coordinated metal centres have been observed in both compounds, when considering the Pb...S and Pb...Br interactions. Both compounds were characterized by FT–IR and diffuse reflectance spectroscopies, as well as by powder X-ray diffraction. Compound (IIa) and its desolvated version (IIb) represent the first structurally characterized PbII compounds containing neutral HSpym and anionic Spym− ligands. After a prolonged time in solution, (IIa) is converted to another compound due to complete deprotonation of HSpym. The structural characterization of (I) and (II) suggests HSpym as a good candidate for the removal of PbII ions from solutions containing thiocyanate or bromide ions.

ChemInform Abstract: Hydrothermal Synthesis and Characterization of a Two-Dimensional Piperazinium Cobalt-Zinc Phosphate via a Metastable One-Dimensional Phase.

ChemInform ◽  
2015 ◽  
Vol 46 (16) ◽  
pp. no-no
Author(s):  
Laura Torre-Fernandez ◽  
Olena A. Khainakova ◽  
Aranzazu Espina ◽  
Zakariae Amghouz ◽  
Sergei A. Khainakov ◽  
...  
Keyword(s):  
Hydrothermal Synthesis ◽  
Zinc Phosphate ◽  
Synthesis And Characterization ◽  
Two Dimensional ◽  
One Dimensional

scholarly journals Cross-Peaks in Simple 2D NMR Experiments from Chemical Exchange of Transverse Magnetization

2019 ◽  
Author(s):  
Chris Waudby ◽  
Tom Frenkiel ◽  
John Christodoulou
Keyword(s):  
Chemical Shift ◽  
Chemical Exchange ◽  
Exchange Process ◽  
2D Nmr ◽  
Two Dimensional ◽  
One Dimensional ◽  
Exchange Processes ◽  
Rich Information ◽  
Multiple Chemical

Two-dimensional correlation measurements such as COSY, NOESY, HMQC and HSQC experiments are central to small molecule and biomolecular NMR spectroscopy, and commonly form the basis of more complex experiments designed to study chemical exchange occurring during additional mixing periods. However, exchange occurring during chemical shift evolution periods can also influence the appearance of such spectra. While this is often exploited through one-dimensional lineshape analysis ('dynamic NMR'), the analysis of exchange across multiple chemical shift evolution periods has received less attention. Here we report that chemical exchange-induced cross-peaks can arise in even the simplest two-dimensional NMR experiments. These cross-peaks can have highly distorted phases that contain rich information about the underlying exchange process. The quantitative analysis of such peaks, from a single 2D spectrum, can provide a highly accurate characterization of underlying exchange processes.

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