scholarly journals Magnetic interactions in LiCu2O2: Single-chain versus double-chain models

2012 ◽  
Vol 86 (2) ◽  
Author(s):  
Rémi Maurice ◽  
Abdul-Muizz Pradipto ◽  
Coen de Graaf ◽  
Ria Broer
Keyword(s):  
Magnetic Interactions ◽  
Single Chain ◽  
Double Chain

scholarly journals Luminescent Ir(iii)–Ln(iii) coordination polymers showing slow magnetization relaxation

2020 ◽  
Vol 7 (23) ◽  
pp. 4580-4592 ◽  
Author(s):  
Kun Fan ◽  
Song-Song Bao ◽  
Ran Huo ◽  
Xin-Da Huang ◽  
Yu-Jie Liu ◽  
...  
Keyword(s):  
Coordination Polymers ◽  
Single Chain ◽  
Double Chain ◽  
Magnetization Relaxation ◽  
Structural Types ◽  
Nir Luminescence

Two structural types of iridium(iii)–lanthanide(iii) coordination polymers, single-chain Ir2Ln and double-chain Ir4Ln2 (Ln = Gd, Dy, Er, and Yb), have been prepared. SMM behaviour and NIR luminescence were observed for the Ir–Er and Ir–Yb systems.

VESICLE TO MICELLE TRANSITION DRIVEN BY SURFACE SOLID-FLUID TRANSITION

2002 ◽  
Vol 16 (01n02) ◽  
pp. 375-382 ◽  
Author(s):  
JANAKY NARAYANAN ◽  
E. MENDES ◽  
C. MANOHAR
Keyword(s):  
Small Angle ◽  
Fluorescence Anisotropy ◽  
Small Angle Neutron Scattering ◽  
Unique Feature ◽  
Ion Pair ◽  
Single Chain ◽  
Double Chain ◽  
Micellar Phase ◽  
Curvature Energy ◽  
Oppositely Charged

This paper reviews the solution behavior of cetyltrimethylammonium hydroxynaphthalene carboxylate (CTAHNC), which has the unique feature of undergoing a transition from vesicle to worm-like micellar phase in three different ways, namely, increase in temperature, addition of a surfactant and on shearing. Fluorescence anisotropy, NMR, rheology, small angle neutron scattering studies etc gave evidence of the vesicle-micelle transition. CTAHNC can be looked upon as a complex formed by two oppositely charged surfactants (CTA+ and HNC-). This ion pair effectively acts as a double-chain lipid and has a tendency to form vesicles. On increasing the temperature, and/or adding single chain surfactants of shearing, the complex dissociates which changes the curvature energy of the surface. This leads to a 'surface melting' that brings forth the vesicle-micelle transition.

scholarly journals Human tumour cathepsin B. Comparison with normal liver cathepsin B

1992 ◽  
Vol 285 (2) ◽  
pp. 427-434 ◽  
Author(s):  
K Moin ◽  
N A Day ◽  
M Sameni ◽  
S Hasnain ◽  
T Hirama ◽  
...  
Keyword(s):  
Cathepsin B ◽  
Human Liver ◽  
Normal Liver ◽  
Polyacrylamide Gels ◽  
Single Chain ◽  
Human Tumour ◽  
Double Chain ◽  
Normal Human Liver ◽  
Human Cathepsin ◽  
Chain Form

Cathepsin B was purified from normal human liver and several human tumour tissues and partially characterized. Three forms of cathepsin B, with molecular masses of 25 kDa, 26 kDa (the two appearing as a doublet) and 30 kDa, were detected in SDS/polyacrylamide gels. The 25-26 kDa doublet was associated with the fractions from tumours and normal liver containing the highest cathepsin B activity. Cathepsin B from both sources showed similar pH optima. Both normal liver and tumour cathepsin B exhibited similar kinetics against selected synthetic substrates. At neutral pH and 24 degrees C, cathepsin B from both normal liver and tumour exhibited a lower Km and a higher kcat./Km than at pH 6.0. Their inhibitory profiles against synthetic inhibitors were also similar. Immunological studies with a monospecific antibody against the mature double-chain form of human liver cathepsin B and an antibody against a cathepsin B-derived synthetic peptide established the immunological similarity of liver and tumour enzymes. The N-terminal sequences of the 25 kDa and 26 kDa forms were identical with that of the heavy chain of the mature double-chain form of human cathepsin B, whereas the N-terminal sequence of the 30 kDa species was identical with that of the single-chain form of human cathepsin B. Treatment of the double-chain form of cathepsin B from normal liver and tumours with the endoglycosidase peptide-N4-(N-acetyl-beta-glucosaminyl)asparagine amidase converted the 26 kDa form into 25 kDa in SDS/polyacrylamide gels, suggesting that cathepsin B may exist as both glycosylated and unglycosylated forms. Our results, in contrast with those reported earlier for mouse cathepsin B, indicate that human liver and tumour cathepsin B are similar.

Purification of bovine cathepsin B: proteomic characterization of the different forms and production of specific antibodies

2003 ◽  
Vol 81 (4) ◽  
pp. 317-326 ◽  
Author(s):  
M A Sentandreu ◽  
L Aubry ◽  
A Ouali
Keyword(s):  
Cathepsin B ◽  
Sodium Dodecyl ◽  
Anion Exchange Chromatography ◽  
Exchange Chromatography ◽  
Peptide Sequence ◽  
Size Exclusion ◽  
Single Chain ◽  
Double Chain ◽  
Bovine Kidney ◽  
Chain Form

Cathepsin B (EC 3.4.22.1) has been highly purified (14 225 fold) from bovine kidney by a rapid procedure that included the preparation of an enriched lysosomal extract, a selective fractionation with ammonium sulphate, size-exclusion chromatography, two cation-exchange chromatographies, and anion-exchange chromatography on diethylaminoethyl–Sephacel. After the last purification step, two hydrolytic peaks against Z-Phe-Arg-AMC were separated from each other, a minor peak corresponding to the cathepsin B single-chain form and a major one representing the double-chain form of cathepsin B. The single-chain form showed a molecular mass of 31 kDa on sodium dodecyl sulphate – polyacrylamide gel electrphoresis (PAGE) under reducing conditions, whereas the heavy chain of the double-chain form appeared as a doublet with molecular masses of 23.4 and 25 kDa, respectively. The identity of the different cathepsin B isoforms and the quality of the final enzyme preparation were confirmed by using two types of antibodies, one against a synthetic peptide sequence and one against purified cathepsin B. The proteomic study confirmed the identity of the different SDS–PAGE protein bands as cathepsin B isoforms and allowed the comparison and study of some structural differences between them at the level of their primary structures.Key words: cathepsin B, bovine kidney, MALDI-TOF, cathepsin B isoforms, antibodies.

A novel magnetotactic Alphaproteobacterium producing intracellular magnetite and calcium-bearing minerals

2021 ◽  
Author(s):  
Peiyu Liu ◽  
Yan Liu ◽  
Xinyi Ren ◽  
Zhifei Zhang ◽  
Xiang Zhao ◽  
...  
Keyword(s):  
Calcium Carbonate ◽  
Calcium Phosphate ◽  
Intracellular Calcium ◽  
Average Length ◽  
Magnetotactic Bacteria ◽  
Magnetic Interactions ◽  
Shaanxi Province ◽  
Rrna Gene ◽  
Single Chain ◽  
Average Size

Magnetotactic bacteria (MTB) are prokaryotes that form intracellular magnetite (Fe 3 O 4 ) or greigite (Fe 3 S 4 ) nanocrystals with tailored sizes, often in chain configurations. Such magnetic particles are each surrounded by a lipid bilayer membrane, called a magnetosome, and provide a model system for studying the formation and function of specialized internal structures in prokaryotes. Using fluorescence-coupled scanning electron microscopy, we identified a novel magnetotactic spirillum, XQGS-1, from freshwater Xingqinggong Lake, Xi’an City, Shaanxi Province, China. Phylogenetic analyses based on 16S rRNA gene sequences indicate that strain XQGS-1 represents a novel genus of the Alphaproteobacteria class in the Proteobacteria phylum. Transmission electron microscope analyses reveal that strain XQGS-1 forms on average 17 ± 3 magnetite magnetosome particles with ideal truncated octahedral morphology with average length and width of 88.3 ± 11.7 nm and 83.3 ± 11.0 nm, respectively. They are tightly organized into a single chain along the cell long axis close to the concave side of the cell. Intra-chain magnetic interactions likely result in these large equidimensional magnetite crystals behaving as magnetically stable single domain particles that enable bacterial magnetotaxis. Combined structural and chemical analyses demonstrate that XQGS-1 cells also biomineralize intracellular amorphous calcium phosphate (2-3 granules per cell; 90.5 ± 19.3 nm average size) and weakly crystalline calcium carbonate (2-3 granules per cell; 100.4 ± 21.4 nm average size) in addition to magnetite. Our results expand the taxonomic diversity of MTB and provide evidence for intracellular calcium phosphate biomineralization in MTB. IMPORTANCE Biomineralization is a widespread process in eukaryotes that form shells, teeth, or bones. It also occurs commonly in prokaryotes, resulting in more than sixty known minerals formed by different bacteria under wide-ranging conditions. Among them, magnetotactic bacteria (MTB) are remarkable because they might represent the earliest organisms that biomineralize intracellular magnetic iron minerals (i.e., magnetite (Fe 3 O 4 ) or greigite (Fe 3 S 4 )). Here we report a novel magnetotactic spirillum (XQGS-1) that is phylogenetically affiliated with the Alphaproteobacteria class. In addition to magnetite crystals, XQGS-1 cells form intracellular sub-micron calcium carbonate and calcium phosphate granules. This finding supports the view that MTB are also an important microbial group for intracellular calcium carbonate and calcium phosphate biomineralization.

scholarly journals The Role of Chain Length and Structure in Surfactant Adsorption at Na-Kaolinite

1998 ◽  
Vol 16 (7) ◽  
pp. 565-575 ◽  
Author(s):  
Jinben Wang ◽  
Buxing Han ◽  
Ming Dai ◽  
Haike Yan ◽  
Zhixin Li ◽  
...  
Keyword(s):  
Chain Length ◽  
Cationic Surfactants ◽  
Adsorption Mechanism ◽  
Alkyl Chain ◽  
Quantitative Description ◽  
Single Chain ◽  
Double Chain ◽  
Intramolecular Association ◽  
Chain Lengths

The adsorption of a series of cationic surfactants with different chain lengths and structures on a non-swelling clay surface (sodium kaolinite) has been studied by microelectrophoresis and adsorption isotherms. It was found that an increase in the number of CH2 groups in the shorter alkyl chain of the double-chain surfactant has much less effect on the adsorption behaviour than changing the length of the alkyl chain in the single-chain surfactants. It is inferred that the effective hydrophobicity of the shorter chains in these double-chain surfactants is reduced by their intramolecular association with the longer chain. A comparison of adsorption and micellization leads to an empirical, quantitative description of the effects of alkyl chain length and structure on adsorption. The adsorption mechanism of cationic surfactants on to Na-kaolinite was discussed.

Structure and Bonding of Tribromocadmates, ACdBr3, A = NH4, Rb, Cs, CH3NH3, (CH3)2NH2, (CH3)4N], [H2NNH3, and (H2N)3C. An X-ray Diffraction and 79-81Br NQR Study

1991 ◽  
Vol 46 (12) ◽  
pp. 1063-1082 ◽  
Author(s):  
V. G. Krishnan ◽  
Shi-qi Dou ◽  
Alarich Weiss
Keyword(s):  
Room Temperature ◽  
High Temperature Phase ◽  
Phase Iii ◽  
Line Spectrum ◽  
Temperature Phase ◽  
X Ray Diffraction ◽  
Single Chain ◽  
Double Chain ◽  
81Br Nqr ◽  
A Chain

Abstract The 79-81Br NQR spectra of tribromocadmates with the cations K⊕, NH4⊕, Rb⊕, Cs⊕, CH3NH3⊕, (CH3)2NH2⊕, (CH3)4N⊕, H2NNH3⊕, and C(NH2)3⊕ were studied as functions of temperature from 77 K on up to T>300 K. CsCdBr3 shows a singlet 81Br NQR spectrum over the whole temperature range studied. [CH3NH3]CdBr3, with one 81Br NQR line spectrum at room temperature, experiences a phase transition at 167 K; below this temperature an 18-line spectrum is observed. In [(CH3)4N]CdBr3 (phase II), at 290 K, a singlet 81Br NQR is present as is in the high temperature phase III (TII.1 , = 390 K); the low temperature phase III (TII,m, = 160 K has a triplet 81Br NQR spectrum. KCdBr3 shows an 81Br NQR doublet spectrum, as do RbCdBr3, [H2NNH3]CdBr3, and [C(NH2)3]CdBr3. 81Br NQR triplets are observed for [(CH3)2NH2]CdBr3 and NH4CdBr3. Several crystal structures were determined (at room temperature). [(CH3)4N]CdBr3: P63/m, Z = 2, a - 940 pm, c = 700 pm, disordered cation, single chain Perovskite with face connected [CdBr6]- octahedra (nearly CsNiCl3-type). [(CH3)2NH2]CdBr3: P21/c, Z = 4, a = 898 pm, 6 = 1377 pm, c = 698 pm, ß = 91.2°, face connected [CdBr3-octahedra single chain Perovskite. NH4CdBr3: Pnma, Z = 4, a = 950 pm, b = 417 pm, c= 1557 pm, with a double chain of condensed [CdBr6]-octahedra, NH4CdCl3-type. [N2H5]CdBr3: P2,/c, Z = 4, a = 395 pm, 6 = 1749 pm,c = 997 pm,ß = 94.2°, double chain polyanion similar to NH4CdBr3. [C(NH2)3]CdBr3: C2/c, Z = 4, a = 778 pm, 6 = 1598 pm, c = 746 pm, ß = 110.2°, a single chain Perovskite with a chain of condensed trigonal bipyramids [CdBr5]. Three types of anion chains of CdBr3 have been observed: Single octahedral chains, face connected; double octahedral chains, edge connected; a trigonal-bipyramidal chain, edge connected. The relation between the crystal structure and the Br NQR is discussed

scholarly journals Magnetic interactions and orbital state in double chain systems investigated by NMR measurements

2011 ◽  
Vol 320 ◽  
pp. 012070 ◽  
Author(s):  
Masayuki Itoh ◽  
Hikaru Takeda ◽  
Yasuhiro Shimizu ◽  
Hiroya Sakurai ◽  
Masahiko Isobe ◽  
...  
Keyword(s):  
Magnetic Interactions ◽  
Double Chain ◽  
Orbital State
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