Dyeing of chemically modified celluloses. II. Effect of chemical modification of cellulose on the dyeing properties of some direct dyes

1977 ◽  
Vol 21 (8) ◽  
pp. 2191-2199 ◽  
Author(s):  
A. Hebeish ◽  
A. Z. Moursi ◽  
M. I. Khalil ◽  
F. A. Abdel-Mohdy
Keyword(s):  
Chemical Modification ◽  
Direct Dyes ◽  
Dyeing Properties ◽  
Chemically Modified

scholarly journals Phosphated Avocado Seed: A Renewable Biomaterial for Preparing a Flame Retardant Biofiller

2021 ◽  
Author(s):  
DAVID Zuluaga-Parra ◽  
L.F Ramos-deValle ◽  
Saul Sanchez ◽  
J.R. Torres-Lubián ◽  
J.A. Rodríguez-Gonzalez ◽  
...  
Keyword(s):  
Thermal Stability ◽  
Chemical Modification ◽  
Flame Retardant ◽  
Photoelectron Spectroscopy ◽  
Morphological Changes ◽  
Ethylene Vinyl Acetate ◽  
Chemically Modified ◽  
Air Atmosphere ◽  
Thermal Stability Of ◽  
Avocado Seed

Abstract The cellulose and starch present in the avocado seed can be chemically modified to obtain biofillers with fire retarding characteristics. The resulting composites could be used as substitute of the corresponding halogenated composites. For this, the avocado seed was first washed, dehydrated and pulverized, and thereafter, chemically modified with phosphoric acid in the presence of urea. This was studied using infrared spectroscopy, nuclear magnetic resonance and X-Ray photoelectron spectroscopy, in order to determine the resulting chemical structure and confirm the presence of the proposed functional groups. In addition, scanning electron microscopy and elemental analysis were used, respectively, to establish the resulting morphological changes, as well as the elements present on the surface of the modified material. Thermogravimetric analysis was also carried out in order to establish the thermal stability of the material and predict the effect on the flame retardancy due to the mentioned chemical modification. Further tests established that the obtained modified structure and morphology of the avocado seed was highly dependent on the method used to dehydrate the pulverized avocado seed. It was also determined that chemical modification greatly increased the thermal stability of the avocado seed in air atmosphere. The flame-retardant effect of the modified avocado seed was assessed in polyethylene/ethylene-vinyl-acetate (PE/EVA) composites via cone calorimeter tests. These results showed that the modified avocado seed decreased the peak of the heat release rate (pHRR) by 50% and the total heat released (THR) by 15%. This phosphated avocado seed could be a good option as a renewable biofiller for polymer composites with enhanced flame-retardant properties.

scholarly journals The nature of the binding site for aromatic compounds in glycogen phosphorylase b

1975 ◽  
Vol 147 (2) ◽  
pp. 369-371 ◽  
Author(s):  
G Soman ◽  
G Philip
Keyword(s):  
Chemical Modification ◽  
Binding Site ◽  
Aromatic Compounds ◽  
Glycogen Phosphorylase ◽  
Relative Effectiveness ◽  
Rabbit Muscle ◽  
Substituent Constant ◽  
Chemically Modified ◽  
Glycogen Phosphorylase B ◽  
Hydrophobic Nature

The inhibition of rabbit muscle glycogen phosphorylase b (1,4-alpha-D-glucan--orthophosphate alpha-glucosyltransferase, EC 2.4.1.1) by aromatic compounds was examined with 15 compounds. The relative effectiveness of the inhibitors correlated well with increasing substituent constant, pi, indicating the hydrophobic nature of the binding site. The inhibition was not affected by the ionic-strength variation of the assay mixtures. The results predict that the course of chemical modification of this enzyme and the properties of the derivatives depend on the nature of the reagent and on the incorporated groups. Many of the dissimilar and sometimes contradictory results reported for chemical-modification studies and for chemically modified phosphorylase b are explained by the findings presented in the paper.

Wood modification with N-methylol and N-methyl compounds: a case study on how non-fixated chemicals in modified wood may affect the classification of their durability

Holzforschung ◽  
2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Lukas Emmerich ◽  
Christian Brischke ◽  
Holger Militz
Keyword(s):  
Chemical Modification ◽  
Cold Water ◽  
Fungal Decay ◽  
Water Leaching ◽  
Chemically Modified ◽  
New Treatment ◽  
Decay Tests ◽  
Modified Wood

Abstract Chemical modification is increasing the durability of wood against biological deterioration. Usually, the effect of a new treatment on the durability of wood is screened in laboratory decay tests, where durability classes are assigned on the basis of the mass loss (ML) caused by degrading fungi. The aim of this study was to demonstrate how non-fixated chemicals in modified wood may affect fungal ML measurements and corresponding durability classification when wood samples are incubated under humid conditions for long periods. Wood blocks were treated with solutions of 1,3-dimethylol-4,5-dihydroxyethyleneurea (DMDHEU), methylated DMDHEU (mDMDHEU) and 1,3-dimethyl-4,5-dihydroxyethyleneurea (DMeDHEU) and subjected to consecutive cold-water leaching cycles. Significant amounts of non-fixated chemicals were removed from the wood by three leaching cycles and might lead to ML mistaken as response of fungal decay. Consequently, the treated material was assigned erroneously by up to four durability classes (DC) worse than material which did not include leachable, non-fixated chemicals. Thus, for a reliable durability classification of chemically modified wood, prolonged leaching procedures are recommended to assure that the measured ML is entirely attributed to fungal decay.

N-Ethylmaleimide-modified actin filaments do not bundle in the presence of α-actinin

1995 ◽  
Vol 73 (1-2) ◽  
pp. 116-122 ◽  
Author(s):  
Aldo Milzani ◽  
Isabella DalleDonne ◽  
Roberto Colombo
Keyword(s):  
Polyethylene Glycol ◽  
Chemical Modification ◽  
Molecular Interactions ◽  
Binding Sites ◽  
Actin Filaments ◽  
Actin Assembly ◽  
Chemically Modified ◽  
C Terminus ◽  
Spatial Reorganization ◽  
Polyethylene Glycol 6000

We show that the modification of actin subdomain 1 by N-ethylmaleimide (NEM), which binds Cys-374 close to the C-terminus of the molecule, inhibits the α-actinin-induced bundling of actin filaments. This effect is not merely related to the block of Cys-374, since N-(1-pyrenyl)iodoacetamide (pyrene-IA) is unable to prevent bundling. Considering that NEM (but not pyrene-IA) influences actin assembly, we suggest that the inhibition of the actin – α-actinin interaction is due to the chemical modification of actin Cys-374 which, by inducing a marked spatial reorganization of actin monomers, is able to modify both the intra- and inter-molecular interactions of this protein. Finally, NEM-modified actin filaments form bundles in the presence of polyethylene glycol 6000 since, in this case, the side by side association of actin filaments does not depend on the accessibility of binding sites nor on the formation of chemical bonds.Key words: chemically modified actin, N-ethylmaleimide, pyrene-IA, Cys-374, actin bundles, α-actinin.

scholarly journals Modification of Cys-837 identifies an actin-binding site in the beta-propeller protein scruin.

1997 ◽  
Vol 8 (3) ◽  
pp. 421-430 ◽  
Author(s):  
S Sun ◽  
M Footer ◽  
P Matsudaira
Keyword(s):  
Chemical Modification ◽  
Binding Site ◽  
Solvent Accessibility ◽  
The Other ◽  
Actin Binding ◽  
Binding Region ◽  
Binding Studies ◽  
Chemically Modified ◽  
Cross Links ◽  
Actin Binding Site

In the acrosomal process of Limulus sperm, the beta-propeller protein scruin cross-links actin into a crystalline bundle. To confirm that scruin has the topology of a beta-propeller protein and to understand how scruin binds actin, we compared the solvent accessibility of cysteine residues in scruin and the acrosomal process by chemical modification with (1,5-IAEDANS). In soluble scruin, the two most reactive cysteines of soluble scruin are C837 and C900, whereas C146, C333, and C683 are moderately reactive. This pattern of reactivity is consistent with the topology of a typical beta-propeller protein; all of the reactive cysteines map to putative loops and turns whereas the unreactive cysteines lie within the predicted interior of the protein. The chemical reactivities of cysteine in the acrosomal process implicate C837 at an actin-binding site. In contrast to soluble scruin, in the acrosomal process, C837 is completely unreactive while the other cysteines become less reactive. Binding studies of chemically modified scruin correlate the extent of modification at C837 with the extent of inhibition of actin binding. Furthermore, peptides corresponding to residues flanking C837 bind actin and narrow a possible actin-binding region to a KQK sequence. On the basis of these studies, our results suggest that an actin-binding site lies in the C-terminal domain of scruin and involves a putative loop defined by C837.

scholarly journals Mechano-sorptive creep of Portuguese pinewood chemically modified

2014 ◽  
Vol 56 (1) ◽  
pp. 30-44
Author(s):  
Duarte Barroso Lopes ◽  
Carsten Mai
Keyword(s):  
Cell Wall ◽  
Chemical Modification ◽  
Experimental Work ◽  
Creep Behaviour ◽  
Hydrophobic Effect ◽  
Untreated Wood ◽  
Melamine Resin ◽  
Chemically Modified ◽  
Modification Process ◽  
Better Than

Summary The effect of chemical modification on mechano-sorptive creep in bending was studied by experimental work. Stakes with 20 × 20 × 400 mm RTL of Portuguese wood species (Pinus pinaster Aiton) modified with 1,3-dimethylol-4,5- dihydroxyethyleneurea (DMDHEU), m-methylated melamine resin (MMF), tetraethoxysilane (TEOS) and amid wax (WA) were measured under asymmetric moistening conditions over a period of 42 days (app. 1000 hours) with stress level (SL) of 12 MPa, according to ENV 1156. The cell wall treatments (DMDHEU and MMF resins) had shown significant reduction of creep (creep factors, kc) when compared to untreated wood under similar conditions. Both types of resins and levels of treatments (different WPG) did not shown significant effects. In the lumen fill treatments, deposit material of TEOS did not affected the creep behaviour (kc); Wax treatment was shown a particular compliance of creep due to avoid exchange moisture (by the hydrophobic effect of wax). The anti-creep efficiency (ACE) correlated better than other mechanical or physical properties imparted by the modification process

Chemical modification of starch with epoxy resin to enhance the interfacial adhesion of epoxy-based glass fiber composites

RSC Advances ◽  
2016 ◽  
Vol 6 (87) ◽  
pp. 84187-84193 ◽  
Author(s):  
Ying Wang ◽  
Hui Li ◽  
Xiaodan Wang ◽  
Hong Lei ◽  
Jichuan Huo
Keyword(s):  
Thermal Properties ◽  
Chemical Modification ◽  
Glass Fiber ◽  
Epoxy Resin ◽  
Interfacial Adhesion ◽  
Glass Fibers ◽  
Fiber Composites ◽  
Mechanical And Thermal Properties ◽  
Glass Fiber Composites ◽  
Chemically Modified

In order to fabricate epoxy-based glass fiber composites with superior mechanical and thermal properties, starch was chemically modified by E-51 epoxy resin, as a sizing for glass fibers.

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