scholarly journals The influence of gibberellin on the level of nucleic acids and other phosphate fractions in maize seedlings

2015 ◽  
Vol 40 (3) ◽  
pp. 467-473
Author(s):  
P. Masłowski ◽  
J. Gniot-Sulżycka ◽  
G. Rześniowiecka
Keyword(s):  
Molecular Weight ◽  
Nucleic Acids ◽  
Soluble Fraction ◽  
Phospholipid Fraction ◽  
The Other ◽  
Low Molecular Weight ◽  
Maize Seedlings ◽  
Other Hand ◽  
Rna And Dna

Treatment of maize seedes with GA3 increased the content of water, the phosphate acid soluble fraction, the phospholipid fraction and the low molecular weight r-RNA, s-RNA, DNA-RNA fractions in 5-days-old seedlings. On the other hand, the contents of RNA and DNA in such seedlings decreased.

scholarly journals The Effects of Three-Dimensional Ligand Immobilization on Kinetic Measurements in Biosensors

Polymers ◽  
2022 ◽  
Vol 14 (2) ◽  
pp. 241
Author(s):  
Elisa Chiodi ◽  
Allison M. Marn ◽  
Monireh Bakhshpour ◽  
Nese Lortlar Ünlü ◽  
M. Selim Ünlü
Keyword(s):  
Molecular Weight ◽  
Three Dimensional ◽  
The Other ◽  
Low Molecular Weight ◽  
Surface Binding ◽  
Kinetic Measurements ◽  
Advantages And Disadvantages ◽  
Affinity Constants ◽  
Other Hand ◽  
The Impact

The field of biosensing is in constant evolution, propelled by the need for sensitive, reliable platforms that provide consistent results, especially in the drug development industry, where small molecule characterization is of uttermost relevance. Kinetic characterization of small biochemicals is particularly challenging, and has required sensor developers to find solutions to compensate for the lack of sensitivity of their instruments. In this regard, surface chemistry plays a crucial role. The ligands need to be efficiently immobilized on the sensor surface, and probe distribution, maintenance of their native structure and efficient diffusion of the analyte to the surface need to be optimized. In order to enhance the signal generated by low molecular weight targets, surface plasmon resonance sensors utilize a high density of probes on the surface by employing a thick dextran matrix, resulting in a three-dimensional, multilayer distribution of molecules. Despite increasing the binding signal, this method can generate artifacts, due to the diffusion dependence of surface binding, affecting the accuracy of measured affinity constants. On the other hand, when working with planar surface chemistries, an incredibly high sensitivity is required for low molecular weight analytes, and furthermore the standard method for immobilizing single layers of molecules based on self-assembled monolayers (SAM) of epoxysilane has been demonstrated to promote protein denaturation, thus being far from ideal. Here, we will give a concise overview of the impact of tridimensional immobilization of ligands on label-free biosensors, mostly focusing on the effect of diffusion on binding affinity constants measurements. We will comment on how multilayering of probes is certainly useful in terms of increasing the sensitivity of the sensor, but can cause steric hindrance, mass transport and other diffusion effects. On the other hand, probe monolayers on epoxysilane chemistries do not undergo diffusion effect but rather other artifacts can occur due to probe distortion. Finally, a combination of tridimensional polymeric chemistry and probe monolayer is presented and reviewed, showing advantages and disadvantages over the other two approaches.

Effect on Polymer Chain Structure Caused by the Molar Fraction of 4-Hydroxybutyrate in Poly(3-hydroxybutyrate- co -4-hydroxybutyrate)

2012 ◽  
Vol 602-604 ◽  
pp. 776-780
Author(s):  
Zhi Qiang Li ◽  
Mei Li ◽  
Wei Jia Fan
Keyword(s):  
Molecular Weight ◽  
Intrinsic Viscosity ◽  
Polymer Chain ◽  
Molar Fraction ◽  
Chain Structure ◽  
The Other ◽  
Mean Square ◽  
Polarizing Microscope ◽  
Other Hand ◽  
The Mean

Poly(3-hydroxybutyrate-co-4-hydroxybutyrate)copolymer [P(3HB-co-4HB)] is a kind of biodegradable high molecular polymer produced by bioaccumulation. Because of the good biodegradability and biocompatibility, P(3HB-co-4HB)s have attracted wide attention . At first, the intrinsic viscosity[η] in good solvent of P(3HB-co-4HB) s with varying contents of 4HB was investigated in different temperature. Second, observed the changes of crystallization gathered state caused by the varying contents of 4HB by polarizing microscope. The results show that to the P(3HB-co-4HB)s in same molecular weight, the intrinsic viscosity[η] in good solvent barely changes when the mole fractions of 4HB increase. On the other hand, the mean square end to end distances[0] of macromolecular flexible chains increase with the mole fractions of 4HB. At the same time, the states of aggregation change from spherulites to dendrites. In this investigation, we discuss the reasons of the differences in depth.

scholarly journals Bridge-therapy with enoxaparin in the preoperative period of endarterectomy

2010 ◽  
Vol 68 (5) ◽  
pp. 775-777
Author(s):  
Jair Leopoldo Raso ◽  
Rogério Zenóbio Darwich ◽  
Francisco de Lucca Jr ◽  
Romeu Valle Santana ◽  
Marco Túlio Tanure ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Mortality Rate ◽  
Prospective Study ◽  
Low Molecular Weight Heparin ◽  
The Other ◽  
Low Molecular Weight ◽  
Preoperative Period ◽  
Safe Strategy ◽  
A Prospective Study ◽  
Bridge Therapy

Cervical clot is one of the complications of endarterectomy. This risk may be higher in patients using aspirin or clopidogrel. On the other hand, stroke may occur if the medication is interrupted before surgery. We carried out a prospective study of 124 endarterectomies in 119 patients in which aspirin or clopidogrel was stopped and a bridge-therapy with enoxaparin was administered preoperatively. There was no case of stroke during the period of the bridge-therapy. One patient developed cervical clot (0.8%) in the fifth postoperative day. Mortality rate in this series was 0.8%. There was no complication directly related to the use of enoxaparin. Bridge-therapy with low molecular weight heparin is a safe strategy for patients elected for endarterectomy

In Vitro Characterization Of Low Molecular Weight Fractions Of Heparin

1981 ◽  
Author(s):  
Jawed Fareed ◽  
Harry L Messmore ◽  
Daniel A Walz ◽  
Jean Choay ◽  
J C Lormeau
Keyword(s):  
Molecular Weight ◽  
The Other ◽  
Low Molecular Weight ◽  
In Vitro Test ◽  
Thrombin Time ◽  
Specific Test ◽  
Platelet Factor ◽  
At Iii ◽  
Heparin Fractions

Numerous extraction, chromatographic (ion exchange, gel, and affinity), chemical and enzymatic degradation methods have been employed to obtain heparin fractions. The present assays to evaluate potency (e.g. pharmacopeial and coagulant) do not truly reflect the antithrombotic properties of these fractions. In addition, the synthetic peptide substrate based assays to measure the anti Xa activity do not correlate with the coagulant anti Xa assays. We have developed an in vitro test battery to evaluate low molecular weight heparin fractions. Porcine mucosal heparin fractions are assayed for anti Xa activity in coagulant and amidolytic assays and the results are expressed as a ratio. The effect of these fractions on coagulant assays such as prothrombin time (PT), partial thromboplastin time (PTT), thrombin time (TT), Stypven time (ST) on freshly prepared normal human plasma (NHP) is determined The retention characteristics of these fractions on platelet factor 4 and AT-III bound sepharose columns were also determined. We have compared the extracted and chemically depolymerized heparin fractions and found that the anti Xa activity doesn’t always correlate with the other parameters studied. The extracted fractions were slightly stronger in the USP assays and showed a biphasic retention on the PF-4 column whereas the chemically depolymerized product showed only one peak. On the other hand, on the AT-III column both fractions showed similar elution patterns. Our studies suggest that heparin and its fractions exhibit differential behavior on various assays and a specific test may not be used as an index of the potency of their antithrombotic effects. Furthermore, the potency of these fractions should be stated on a weight basis when evaluated in the in vivo animal models rather than in terms of a specific test (e.g. anti Xa activity and US Pharmacopeial assays).

STUDIES ON THE ISOLATION AND NATURE OF THE 'TERREGENS FACTOR'

1954 ◽  
Vol 32 (1) ◽  
pp. 400-406 ◽  
Author(s):  
M. O. Burton ◽  
F. J. Sowden ◽  
A. G. Lochhead
Keyword(s):  
Amino Acids ◽  
Molecular Weight ◽  
Ferric Iron ◽  
Test Organism ◽  
The Other ◽  
Inorganic Salts ◽  
Low Molecular Weight ◽  
Straight Chain ◽  
Heat Stable ◽  
Growth Promoting

A procedure is described for the production and concentration of the 'terregens factor' (TF), a bacterial growth promoting substance synthesized by Arthrobacter pascens and essential for the growth of Arthrobacter terregens. From culture filtrates of A. pascens cultivated in a medium of inorganic salts and sucrose, concentrates of TF may be obtained that are active at 0.001 μgm. Per ml., heat stable and contain about 12.7% nitrogen. Acid hydrolysis yielded a number of amino acids, including glutamic acid, glycine, α–alanine, valine, leucine, proline, lysine, and arginine, as well as some unidentified compounds; however, TF does not appear to be a low molecular weight straight chain peptide.Although TF contains no iron, it combines readily with ferrous or ferric iron to form reddish-brown complexes with this metal. Activity for A. terregens is shown by certain iron containing complexes as hemin, coprogen, and ferrichrome. On the other hand none is shown by cytochrome or pulcherrimin; however, aspergillic acid, structurally related to the latter, possesses some growth promoting activity for the test organism.

Fractionation of Rubber

1941 ◽  
Vol 14 (1) ◽  
pp. 1-14 ◽  
Author(s):  
George F. Bloomfield ◽  
Ernest Harold Farmer
Keyword(s):  
Molecular Weight ◽  
Soluble Fraction ◽  
Insoluble Fraction ◽  
The Other ◽  
Major Fraction ◽  
Low Concentrations ◽  
Fractional Dissolution ◽  
Judicious Choice ◽  
Hydrocarbon Molecules ◽  
Soluble Fractions

Abstract Latex rubber which has been purified to the point at which it contains an insignificant amount of nitrogen can be separated by fractional dissolution in a mixture of petroleum and acetone into a series of hydrocarbon fractions of decreasing solubility and increasing molecular magnitude. All these fractions except the highest are soluble in petroleum and in benzene. Crepe rubber, on the other hand, appears invariably to contain a small, most-soluble fraction of oxygenated rubber, and a small similar quite insoluble fraction of material of high molecular weight. Between these extremes the rubber can be divided into fractions of increasing molecular weight, although, up to the present, about 70 per cent of the total rubber has appeared in a single fraction. It may be possible later, by judicious choice of another pair of solvents, to resolve this major fraction into a series of subfractions. Kemp and Peters refer to the effect of polar nonsolvents in reducing the viscosity of rubber solutions and also in assisting to bring gel rubber into solution, phenomena to which the polar molecules conceivably contribute by countering the forces of association between the rubber molecules. The present series of fractionations was conducted throughout in the presence of a polar nonsolvent (acetone), and hence may be considered to approach towards a separation of true rubber molecules as distinct from molecular aggregates. It is found, however, that, whereas the more soluble fractions of acetone-extracted crepe rubber contain small proportions of nitrogen, the least soluble fractions contain substantial proportions. Any effect which the nitrogenous material may have in assisting to link together hydrocarbon molecules to which it is attached, i. e., in contributing to the high-molecular condition of a portion of natural rubber, remains at present uncertain in character. The fractions of rubber, and especially the higher ones, show a strong tendency to become insoluble when they have once been freed from the last traces of solvent. It seems doubtful whether the decreased solubility is due to oxygen as it would require to be effective at exceedingly low concentrations.

scholarly journals Viscoelastic Properties of Unentangled Multicyclic Polystyrenes

Polymers ◽  
2018 ◽  
Vol 10 (9) ◽  
pp. 973 ◽  
Author(s):  
Zhi-Chao Yan ◽  
Md. Hossain ◽  
Michael Monteiro ◽  
Dimitris Vlassopoulos
Keyword(s):  
Molecular Weight ◽  
Shear Viscosity ◽  
Viscoelastic Properties ◽  
Dilution Effect ◽  
The Other ◽  
Low Molecular Weight ◽  
Zero Shear Viscosity ◽  
Rouse Model ◽  
Loop Size ◽  
Linear Chains

We report on the viscoelastic properties of linear, monocyclic, and multicyclic polystyrenes with the same low molecular weight. All polymers investigated were found to exhibit unentangled dynamics. For monocyclic polymers without inner loops, a cyclic-Rouse model complemented by the contribution of unlinked chains (whose fraction was determined experimentally) captured the observed rheological response. On the other hand, multicyclic polymers with inner loops were shown to follow a hierarchical cyclic-Rouse relaxation with the outer loops relaxing first, followed by the inner loop relaxation. The influence of unlinked linear chains was less significant in multicyclic polymers with inner loops. The isofrictional zero-shear viscosity decreased with increasing number of constrained segments on the coupling sites, which was attributed to the decreasing loop size and the dilution effect due to the hierarchical relaxation.

Fractionation of the Color of Pure Maple and Other Sirups by Gel Filtration

1965 ◽  
Vol 48 (3) ◽  
pp. 493-497
Author(s):  
E E Stinson ◽  
C O Willits
Keyword(s):  
Molecular Weight ◽  
Gel Filtration ◽  
Cane Sugar ◽  
The Other ◽  
Low Molecular Weight ◽  
Brown Sugar ◽  
Maple Sugar ◽  
Molecular Weight Fractions ◽  
Color Fraction

Abstract The colorants of pure maple, cane and maple, refined cane sugar, and light brown sugar sirups were separated into two fractions, one of high- and the other of lowmolecular weights, by means of gel filtration. The ratio of the amounts of high- to the low-molecular weight fractions of pure maple was the lowest of the four sirups and serves as a means of differentiation from these sirups. The color fraction ratio was highest for blended cane-maple sugar sirup. Many maple sirups are also distinguished by a pink band formed on the gel filtration column.

Butyl Networks Containing Unattached Polyisobutylene Chains: Part II, Correlation of Tear, Tensile, and Hysteretic Properties

1986 ◽  
Vol 59 (2) ◽  
pp. 347-360 ◽  
Author(s):  
G. R. Hamed ◽  
F. Ogbimi
Keyword(s):  
Molecular Weight ◽  
Crack Tip ◽  
The Other ◽  
Low Molecular Weight ◽  
Load Bearing ◽  
Tear Strength ◽  
Tearing Energy ◽  
High Molecular Weight Polyisobutylene ◽  
Hysteretic Properties ◽  
Crack Tip Blunting

Abstract Butyl networks containing either unattached polyisobutylene chains or a low-molecular-weight plasticizer have been made by crosslinking butyl rubber in the presence of one of these diluents. With dodecane as a plasticizer, tear strength is reduced both because of a decrease in the density of load-bearing chains and diminished hysteresis. On the other hand, when the diluent is a high-molecular-weight polyisobutylene, tear strength is enhanced if the test rate is sufficiently high. In this case, the polyisobutylene chains are load bearing (at least initially) before slipping at higher strains to relieve local crack-tip stresses and blunt the propagating tear. This hysteretic mechanism delays the onset of crack propagation, thereby enhancing the fracture energy. However, at low tear rates, in which there is adequate time for the unattached chains to relax such that they bear little load and hysteresis is minimized, tear strength decreases with increasing free-chain content—much the same as occurs with a low-molecular-weight diluent. Finally, under conditions in which the average propagating tearing energy is enhanced for the butyl-polyisobutylene system, the initiation tearing energy is increased only moderately. This suggests that crack-tip blunting during steady-state tearing is at least partially responsible for increases in strength in the presence of free chains.

Sulphydryl Oxidation in the Mechanism of Molecular-Weight Conversion of Renin in Dog Kidney

1982 ◽  
Vol 62 (2) ◽  
pp. 157-162 ◽  
Author(s):  
Fumihiko Ikemoto ◽  
Kazuo Takaori ◽  
Hiroshi Iwao ◽  
Kenjiro Yamamoto
Keyword(s):  
Molecular Weight ◽  
High Molecular Weight ◽  
Renal Cortex ◽  
Soluble Fraction ◽  
Low Molecular Weight ◽  
Oxidizing Agent ◽  
Nitrobenzoic Acid ◽  
Binding Substance ◽  
Sh Group ◽  
Dog Kidney

1. A high-molecular-weight renin (Mr 60 000) was formed by the reaction of a low-molecular-weight renin (Mr 40 000) with a renin-binding substance in canine renal cortical extract in the presence of the sulphydryl (SH) group oxidizing agent potassium tetrathionate; thus the reaction required SH oxidation. 2. Renin extracted from isolated renin granules was adsorbed on to thiopropyl Sepharose 6B, and then liberated with dithiothreitol (50 mmol/l), indicating that it possessed on SH moiety(s). 3. However, the renin was capable of reaction with the renin-binding substance even after its SH moiety (or moieties) was protected with 5,5′-dithiobis-(2-nitrobenzoic acid). 4. The high-molecular-weight renin was converted into the low-molecular-weight renin by incubation (37°C, 15 min) with cytosol (soluble fraction) of renal cortex and liver. Such converting ability was diminished after the cytosol was treated with perchloric acid or potassium tetrathionate. 5. These results suggest that the reaction of renin with the renin-binding substance does not require disulphide bond(s) and that an enzymelike substance which is sensitive to SH oxidation is involved in the conversion from the high-molecular-weight renin into the low-molecular weight renin.

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