scholarly journals Influence of Cation Exchange on the 27Al-NMR Spectra of Zeolites

2003 ◽  
Vol 217 (12) ◽  
pp. 1613-1626 ◽  
Author(s):  
W. Masierak ◽  
T. Emmler ◽  
Gerd Buntkowsky ◽  
A. Gutsze
Keyword(s):  
Cation Exchange ◽  
Nmr Spectra ◽  
Structural Changes ◽  
Divalent Cations ◽  
Second Order ◽  
Quadrupolar Coupling ◽  
Frame Work ◽  
Ion Radius ◽  
First Time

AbstractThe influence of cation exchange on the 27Al-NMR spectra of NaA-zeolites has been studied by 27Al-MAS- and MQ-MAS-Solid State-NMR. From the 27Al-spectra a characterization of the different Al sites in the A zeolites according to their chemical environment and the structural changes on the aluminosilicate network caused by the cation exchange are obtained. It is found that the exchange with cations with smaller ion-radius cause stronger distortions of the 27Al-NMR-spectra than exchange with larger cations like Ba2+. Employing MQ-MAS spectroscopy these distortions are revealed as second order quadrupolar effects for the smaller cations and as a combination of chemical shift and second order quadrupolar interaction for the Ba cation. These changes of the quadrupolar coupling are interpreted numerically via calculations of the lowering of the symmetry of the EFG tensor. Finally it is found that the exchange with divalent cations leads to distortions of the zeolitic framework and the formation of an extra-framework aluminum. To the best of our knowledge this is for the first time that evidence for the production of extra frame work aluminum by pure cation exchange without any thermal treatment has been found in type A zeolites.

scholarly journals Characterization of Each St and Y Genome Chromosome of Roegneria grandis Based on Newly Developed FISH Markers

2021 ◽  
pp. 213-222
Author(s):  
Dandan Wu ◽  
Xiaoxia Zhu ◽  
Lu Tan ◽  
Haiqin Zhang ◽  
Lina Sha ◽  
...  
Keyword(s):  
Structural Changes ◽  
Distribution Patterns ◽  
Proximal Region ◽  
Genome Chromosome ◽  
High Affinity ◽  
Complete Set ◽  
Genome Analyses ◽  
First Time ◽  
Homoeologous Chromosomes

The genera of the tribe Triticeae (family Poaceae), constituting many economically important plants with abundant genetic resources, carry genomes such as St, H, P, and Y. The genome symbol of <i>Roegneria</i> C. Koch (Triticeae) is StY. The St and Y genomes are crucial in Triticeae, and tetraploid StY species participate extensively in polyploid speciation. Characterization of St and Y nonhomologous chromosomes in StY-genome species could help understand variation in the chromosome structure and differentiation of StY-containing species. However, the high genetic affinity between St and Y genome and the deficiency of a complete set of StY nonhomologous probes limit the identification of St and Y genomes and variation of chromosome structures among <i>Roegneria</i> species. We aimed to identify St- and Y-enhanced repeat clusters and to study whether homoeologous chromosomes between St and Y genomes could be accurately identified due to high affinity. We employed comparative genome analyses to identify St- and Y-enhanced repeat clusters and generated a FISH-based karyotype of <i>R. grandis</i> (Keng), one of the taxonomically controversial StY species, for the first time. We explored 4 novel repeat clusters (StY_34, StY_107, StY_90, and StY_93), which could specifically identify individual St and Y nonhomologous chromosomes. The clusters StY_107 and StY_90 could identify St and Y addition/substitution chromosomes against common wheat genetic backgrounds. The chromosomes V_St, VII_St, I_Y, V_Y, and VII_Y displayed similar probe distribution patterns in the proximal region, indicating that the high affinity between St and Y genome might result from chromosome rearrangements or transposable element insertion among V_St/Y, VII_St/Y, and I_Y chromosomes during allopolyploidization. Our results can be used to employ FISH further to uncover the precise karyotype based on colinearity of Triticeae species by using the wheat karyotype as reference, to analyze diverse populations of the same species to understand the intraspecific structural changes, and to generate the karyotype of different StY-containing species to understand the interspecific chromosome variation.

Characterization of transport mechanisms and determinants critical for Na+-dependent Pisymport of the PiT family paralogs human PiT1 and PiT2

2006 ◽  
Vol 291 (6) ◽  
pp. C1377-C1387 ◽  
Author(s):  
Pernille Bøttger ◽  
Susanne E. Hede ◽  
Morten Grunnet ◽  
Boy Høyer ◽  
Dan A. Klærke ◽  
...  
Keyword(s):  
Mammalian Cells ◽  
Divalent Cations ◽  
Maximal Activity ◽  
Xenopus Laevis Oocytes ◽  
Transport Function ◽  
Knockout Mutant ◽  
Uptake Medium ◽  
The Impact ◽  
First Time

The general phosphate need in mammalian cells is accommodated by members of the Pitransport (PiT) family ( SLC20), which use either Na+or H+to mediate inorganic phosphate (Pi) symport. The mammalian PiT paralogs PiT1 and PiT2 are Na+-dependent Pi(NaPi) transporters and are exploited by a group of retroviruses for cell entry. Human PiT1 and PiT2 were characterized by expression in Xenopus laevis oocytes with32Pias a traceable Pisource. For PiT1, the Michaelis-Menten constant for Piwas determined as 322.5 ± 124.5 μM. PiT2 was analyzed for the first time and showed positive cooperativity in Piuptake with a half-maximal activity constant for Piof 163.5 ± 39.8 μM. PiT1- and PiT2-mediated Na+-dependent Piuptake functions were not significantly affected by acidic and alkaline pH and displayed similar Na+dependency patterns. However, only PiT2 was capable of Na+-independent Pitransport at acidic pH. Study of the impact of divalent cations Ca2+and Mg2+revealed that Ca2+was important, but not critical, for NaPitransport function of PiT proteins. To gain insight into the NaPicotransport function, we analyzed PiT2 and a PiT2 Pitransport knockout mutant using22Na+as a traceable Na+source. Na+was transported by PiT2 even without Piin the uptake medium and also when Pitransport function was knocked out. This is the first time decoupling of Pifrom Na+transport has been demonstrated for a PiT family member. Moreover, the results imply that putative transmembrane amino acids E55and E575are responsible for linking Piimport to Na+transport in PiT2.

scholarly journals Characterization of all second-order nonlinear-optical coefficients of organic N-benzyl-2-methyl-4-nitroaniline crystal

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Takashi Notake ◽  
Masahiro Takeda ◽  
Shuji Okada ◽  
Takuya Hosobata ◽  
Yutaka Yamagata ◽  
...  
Keyword(s):  
Nonlinear Optical ◽  
Organic Materials ◽  
Second Order ◽  
Organic N ◽  
Application Study ◽  
Optical Surfaces ◽  
Nlo Property ◽  
Diamond Blade ◽  
First Time

Abstract Full elements of second-order nonlinear optical (NLO) tensor can be completely characterized for an organic NLO crystal for the first time. As-grown bulk N-benzyl-2-methyl-4-nitroaniline (BNA) crystal was processed to expose (100) and (010) crystal orientations with fine optical surfaces by using precision lathe and diamond blade. Then, every five nonvanishing second-order NLO coefficient of BNA can be determined quantitatively using the precisely processed crystals based on 1st-kind Maker fringe measurements. Our method makes it possible to clarify uncertain NLO property of any organic materials and to accelerate application study via precise device fabrications even for fragile organic materials.

Characterization of Eucalyptus and Chemically Related Exudates by Nuclear Magnetic Resonance Spectroscopy

2007 ◽  
Vol 60 (11) ◽  
pp. 862 ◽  
Author(s):  
Joseph B. Lambert ◽  
Yuyang Wu ◽  
Michael A. Kozminski ◽  
Jorge A. Santiago-Blay
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Solid State ◽  
1H Nmr Spectroscopy ◽  
Nmr Spectra ◽  
Flowering Plants ◽  
Resonance Spectroscopy ◽  
The Family ◽  
First Time ◽  
Genus Eucalyptus

Exudates from six species of the genus Eucalyptus and one of the genus Corymbia (formerly Eucalyptus), from the family Myrtaceae, have been characterized by solid-state 13C and solution 1H NMR spectroscopy for the first time. Although these eucalypt kinos, as these exudates often are called, resemble resin (terpenoid) and gum (carbohydrate) exudates in physical appearance, their NMR spectra are dramatically different. In addition to lacking the characteristic terpene saturated resonances, they exhibit strong unsaturated resonances, which are weak for resins and absent for gums. We additionally report that exudates from genera of several other families of flowering plants (Amyris, Centrolobium, Guaiacum, Liquidambar, and Prosopis) also exhibit part or all of this kino spectroscopic signature.

Molecular Second-Order Optical Nonlinearity of Push-Pull Bisdithiolene Nickel Complexes

1997 ◽  
Vol 488 ◽  
Author(s):  
Chin-Ti Chen ◽  
Sish-Yuan Liao ◽  
Kuan-Jiuh Lin ◽  
Long-Li Lai
Keyword(s):  
Nonlinear Optical ◽  
Nickel Complexes ◽  
Optical Nonlinearity ◽  
Second Order ◽  
Synthesis And Characterization ◽  
Crystal Data ◽  
X Ray ◽  
Donor Acceptor ◽  
First Time

AbstractThe synthesis and characterization of donor-acceptor substituted unsymmetrical bisdithiolene nickel complexes are described for the first time. X-ray single crystal data indicate that the complexes exist with two types of bonding structures, namely, the π-localized and π-delocalized structures. The relation between bonding structures and the molecular second-order nonlinear optical properties, i.e., solvatochromism, dipole moment, and molecular first hyperpolarizability is discussed.

Spectroscopic Characterization of the Selenium-Rich Heterocycles Se5S, Se7S, and 1,5-Se6S2

1991 ◽  
Vol 46 (12) ◽  
pp. 1674-1678 ◽  
Author(s):  
Ralf Steudel ◽  
Maria Papavassiliou ◽  
Frank Baumgart
Keyword(s):  
Nmr Spectroscopy ◽  
Nmr Spectra ◽  
Spectroscopic Characterization ◽  
Reversed Phase ◽  
Nucleophilic Attack ◽  
Crystal Data ◽  
Reversed Phase Hplc ◽  
Cyclic Molecules ◽  
First Time

Se5S in CS2 solution at 20°C spontaneously decomposes to give a mixture of 8 selenium-rich cyclic molecules which have been identified by reversed-phase HPLC and 77Se NMR spectroscopy as Se6, Se7, Se8, Se6S, Se7S, 1,2-Se6S2, 1,5-Se6S2, and 1,4-Se4S2. NMR spectra of Se5S, Se7S, and 1,5-Se6S2 have been measured for the first time; Raman spectra of solid Se5S and Se7S as well as crystal data of Se7S are reported in addition. A mechanism based on nucleophilic attack on Se5S is proposed for the formation of the products.

scholarly journals Permselectivity of Cation Exchange Membranes Modified by Polyaniline

Membranes ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 227
Author(s):  
Irina Falina ◽  
Natalia Loza ◽  
Sergey Loza ◽  
Ekaterina Titskaya ◽  
Nazar Romanyuk
Keyword(s):  
Cation Exchange ◽  
Divalent Cations ◽  
Structural Parameters ◽  
Membrane Surface ◽  
Specific Conductivity ◽  
Current Voltage ◽  
Before And After ◽  
Novel Method ◽  
Doubly Charged

This work discusses the applicability of polyaniline-modified cation exchange membranes for the separation of monovalent/divalent cations by electrodialysis. A novel method of membrane modification directly in the electrodialysis unit is used to prepare permselective membranes. Complex characterization of the membranes before and after modification allows revealing the influence of membrane matrix on the modification efficiency. The characterization of the membranes includes determination of the diffusion permeability, specific conductivity and current–voltage curves in HCl, NaCl and CaCl2 solutions, as well as transport-structural parameters of the extended three-wire model. The characterization results are used to predict the influence of the modification on membrane permselectivity. The competitive mass transfer of singly and doubly charged cations in the electrodialysis process is investigated in underlimiting and overlimiting currents. Electrodialysis desalination of a solution containing Na+/Ca2+ or H+/Ca2+ cations shows that the modification leads to an increase in membrane permselectivity to single-charged cations due to the repulsion of Ca2+ ions from the positively charged membrane surface. The permselectivity of the polyaniline-modified perfluorinated membrane to H+ in the mixture of H+/Ca2+ cations is observed in all current regimes.

scholarly journals Characterization of the Modulatory Effect of Hydroxychloroquine on ACE2 Activity: New Insights in relation to COVID-19

2021 ◽  
Vol 2021 ◽  
pp. 1-5
Author(s):  
Juan E. Tichauer ◽  
Dagoberto Soto ◽  
Max Andresen
Keyword(s):  
Structural Changes ◽  
Three Dimensional ◽  
Specific Inhibitor ◽  
In Vitro System ◽  
Trial Outcomes ◽  
A Cell ◽  
The One ◽  
First Time

Chloroquine (CQ) and hydroxychloroquine (HCQ) have shown the ability to inhibit in vitro viral replications of coronaviridae viruses such as SARS-CoV and SARS-CoV-2. However, clinical trial outcomes have been disparate, suggesting that CQ and HCQ antiviral mechanisms are not fully understood. Based on three-dimensional structural similarities between HCQ and the known ACE2 specific inhibitor MLN-4760, we compared their modulation on ACE2 activity. Here we describe, for the first time, in a cell-free in vitro system that HCQ directly and dose-dependently inhibits the activity of recombinant human ACE2, with a potency similar to the MLN-4760. Further analysis suggests that HCQ binds to a noncompetitive site other than the one occupied by MLN-4760. We also determined that the viral spike glycoprotein segment that comprises the RBD segment has no effect on ACE2 activity but unexpectedly was able to partially reverse the inhibition induced by HCQ but not that by MLN-4760. In summary, here we demonstrate the direct inhibitory action of HCQ over the activity of the enzyme ACE2. Then, by determining the activity of ACE2, we reveal that the interaction with the spike protein of SARS-CoV-2 leads to structural changes that at least partially displace the interaction of the said enzyme with HCQ. These results may help to explain why the effectiveness of HCQ in clinical trials has been so variable. Additionally, this knowledge could be used for to develop techniques for the detection of SARS-CoV-2.

TBE in Sweden

2020 ◽  
Keyword(s):  
Genetic Characterization ◽  
Immunoglobulin M ◽  
Enzyme Linked Immunosorbent Assay ◽  
Second Phase ◽  
Serum Samples ◽  
Tick Borne Encephalitis ◽  
Specific Immunoglobulin ◽  
Tick Borne Encephalitis Virus ◽  
First Time

Tick-borne encephalitis virus (TBEV) was isolated for the first time in Sweden in 1958 (from ticks and from 1 tick-borne encephalitis [TBE] patient).1 In 2003, Haglund and colleagues reported the isolation and antigenic and genetic characterization of 14 TBEV strains from Swedish patients (samples collected 1991–1994).2 The first serum sample, from which TBEV was isolated, was obtained 2–10 days after onset of disease and found to be negative for anti-TBEV immunoglobulin M (IgM) by enzyme-linked immunosorbent assay (ELISA), whereas TBEV-specific IgM (and TBEV-specific immunoglobulin G/cerebrospinal fluid [IgG/CSF] activity) was demonstrated in later serum samples taken during the second phase of the disease.

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