Softening Characteristics of Wet Wood under Quasi Static Loading

Holzforschung ◽  
2000 ◽  
Vol 54 (5) ◽  
pp. 557-560 ◽  
Author(s):  
S. Hamdan ◽  
W. Dwianto ◽  
T. Morooka ◽  
M. Norimoto
Keyword(s):  
Glass Transition ◽  
Relaxation Process ◽  
Wood Species ◽  
Static Loading ◽  
Chemical Structure ◽  
Steam Treatment ◽  
Radial Compression ◽  
Softening Behavior ◽  
Broad Leaf ◽  
The Difference

Summary In order to examine the possible influences of temperature on the wood constituents, two groups of wood species namely softwood (needle leaf wood) and hardwood (broad leaf wood) were subjected to heat or steam treatment during large radial compression between 0°C and 200°C. Two well-defined softening regions are observed. Both species showed the glass transition Tg of lignin at ~ 90°C and ~ 60°C for softwood and hardwood respectively and a second transition region at ~ 160°C. The softening behavior between the first and second transition in softwood is in contrast with the softening behavior of hardwood. This difference reflects the difference in the distribution of the relaxation process due to lignin, which suggests the difference in chemical structure of lignin between softwood and hardwood.

GAGs-Potentiated Inhibition of Thrombin, Factor Xa and Plasmin in Plasma and in a Purified System Containing Antithrombin III – Correlation with Total Charge Density

1981 ◽  
Vol 46 (04) ◽  
pp. 749-751 ◽  
Author(s):  
E Cofrancesco ◽  
A Vigo ◽  
E M Pogliani
Keyword(s):  
Charge Density ◽  
Chemical Structure ◽  
Antithrombin Iii ◽  
Factor Xa ◽  
Total Charge ◽  
Pure System ◽  
At Iii ◽  
Total Charge Density ◽  
The Difference ◽  
Inhibition Of Thrombin

SummaryThe ability of heparin and related glycosaminoglycans (GAGs) to accelerate the inhibition of thrombin, factor Xa and plasmin in plasma and in a purified system containing antithrombin III (At III) was studied using chromogenic peptide substrate assaysThere was a good correlation between the charge density of the mucopolysaccharides and the activities investigated. While the difference between potentiation of the antithrombin activity by GAGs in plasma and in the purified system was slight, the inhibition of factor Xa in plasma was more pronounced than in the presence of purified At III, indicating the mechanisms for GAGs-potentiated inhibition of thrombin and factor Xa are not identical.For the antiplasmin activity, there was a good correlation between the chemical structure and biological activity only in the pure system, confirming that the antithrombin-GAG complex plays a very limited role in the inactivation of plasmin in plasma.

scholarly journals Effects of Amino Acid Side-Chain Length and Chemical Structure on Anionic Polyglutamic and Polyaspartic Acid Cellulose-Based Polyelectrolyte Brushes

Polymers ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1789
Author(s):  
Dmitry Tolmachev ◽  
George Mamistvalov ◽  
Natalia Lukasheva ◽  
Sergey Larin ◽  
Mikko Karttunen
Keyword(s):  
Glutamic Acid ◽  
Chain Length ◽  
Chemical Structure ◽  
Side Chain ◽  
Side Chains ◽  
Side Chain Length ◽  
Polyelectrolyte Brushes ◽  
Grafting Density ◽  
The Difference ◽  
Cellulose Surface

We used atomistic molecular dynamics (MD) simulations to study polyelectrolyte brushes based on anionic α,L-glutamic acid and α,L-aspartic acid grafted on cellulose in the presence of divalent CaCl2 salt at different concentrations. The motivation is to search for ways to control properties such as sorption capacity and the structural response of the brush to multivalent salts. For this detailed understanding of the role of side-chain length, the chemical structure and their interplay are required. It was found that in the case of glutamic acid oligomers, the longer side chains facilitate attractive interactions with the cellulose surface, which forces the grafted chains to lie down on the surface. The additional methylene group in the side chain enables side-chain rotation, enhancing this effect. On the other hand, the shorter and more restricted side chains of aspartic acid oligomers prevent attractive interactions to a large degree and push the grafted chains away from the surface. The difference in side-chain length also leads to differences in other properties of the brush in divalent salt solutions. At a low grafting density, the longer side chains of glutamic acid allow the adsorbed cations to be spatially distributed inside the brush resulting in a charge inversion. With an increase in grafting density, the difference in the total charge of the aspartic and glutamine brushes disappears, but new structural features appear. The longer sides allow for ion bridging between the grafted chains and the cellulose surface without a significant change in main-chain conformation. This leads to the brush structure being less sensitive to changes in salt concentration.

scholarly journals Influence of Dimethacrylate Monomer on the Polymerization Efficacy of Resin-Based Dental Cements—FTIR Analysis

Polymers ◽  
2022 ◽  
Vol 14 (2) ◽  
pp. 247
Author(s):  
Aleksandra Maletin ◽  
Ivan Ristic ◽  
Tanja Veljovic ◽  
Bojana Ramic ◽  
Tatjana Puskar ◽  
...  
Keyword(s):  
Spectral Analysis ◽  
Clinical Practice ◽  
Chemical Structure ◽  
Cementitious Materials ◽  
Degree Of Polymerization ◽  
Cementitious Material ◽  
Ftir Analysis ◽  
Dental Cement ◽  
Polymerization Mechanism ◽  
The Difference

The degree of polymerization for dimethacrylate resin-based materials (BisGMA, TEGDMA, UDMA, HEMA) ranges from 55 to 75%. Literature data indicate that polymerization efficacy depends, among other factors, on the type of methacrylate resin comprising the material. The aim of this study was to evaluate the polymerization efficacy of four dental cement materials characterized by different polymerization mechanisms using FTIR analysis. In the present study, the FTIR method was adopted to analyze the degree of polymerization efficacy of four resin-based dental cement materials, two of which were self-cured and two were dual-cured cements. The IR spectral analysis was performed 24 h after the polymerization of the cementitious material. RelyX ARC cement exhibits the lowest polymerization efficacy (61.3%), while that of Variolink II (85.8%) and Maxcem Elite is the highest (90.1%). Although the efficacy of self-cured cements appears to be superior, the difference is not statistically significant (p = 0.280). Polymerization efficacy largely depends on the chemical structure of the material in terms of the presence of a particular methacrylate resin and less on the polymerization mechanism itself, i.e., whether it is a self-cured or dually cured dental cement. Thus, in clinical practice, cementitious materials with a higher proportion of TEGDMA compared with BisGMA are recommended.

scholarly journals Investigation on compatibility of PLA/PBAT blends modified by epoxy-terminated branched polymers through chemical micro-crosslinking

e-Polymers ◽  
2020 ◽  
Vol 20 (1) ◽  
pp. 39-54 ◽  
Author(s):  
Bo Wang ◽  
Yujuan Jin ◽  
Kai’er Kang ◽  
Nan Yang ◽  
Yunxuan Weng ◽  
...  
Keyword(s):  
Lactic Acid ◽  
Glass Transition ◽  
Sem Analysis ◽  
Branched Polymers ◽  
Poly Lactic Acid ◽  
Elongation At Break ◽  
Butylene Terephthalate ◽  
The Difference ◽  
Physical And Chemical ◽  
The Impact

AbstractIn this study, a type of epoxy-terminated branched polymer (ETBP) was used as an interface compati- bilizer to modify the poly lactic acid (PLA)/poly(butylene adipate-co-butylene terephthalate) (PBAT) (70/30) blends. Upon addition of ETBP, the difference in glass transition temperature between PLA and PBAT became smaller. By adding 3.0 phr of ETBP, the elongation at break of the PLA/PBAT blends was found increased from 45.8% to 272.0%; the impact strength increased from 26.2 kJ·m−2 to 45.3 kJ·m−2. In SEM analysis, it was observed that the size of the dispersed PBAT particle decreased with the increasing of ETBP content. These results indicated that the compatibility between PLA and PBAT can be effectively enhanced by using ETBP as the modifier. The modification mechanism was discussed in detail. It proposes that both physical and chemical micro-crosslinking were formed, the latter of which was confirmed by gel content analysis.

scholarly journals Reduction of titanium oxide in the presence of nickel by nonequilibrium hydrogen gas

2009 ◽  
Vol 24 (7) ◽  
pp. 2391-2399 ◽  
Author(s):  
Hidehiro Sekimoto ◽  
Tetsuya Uda ◽  
Yoshitaro Nose ◽  
Shigeo Sato ◽  
Hiroaki Kakiuchi ◽  
...  
Keyword(s):  
Low Temperature ◽  
Relaxation Process ◽  
Reduction Potential ◽  
Hydrogen Plasma ◽  
Equilibrium Phase ◽  
Hydrogen Gas ◽  
X Ray Diffraction ◽  
Energy Process ◽  
X Ray ◽  
The Difference

We investigated the reduction of TiO2 in the presence of Ni by nonequilibrium hydrogen gas, including low-temperature hydrogen plasma at 800 °C and supercooled monatomic hydrogen at 1000 °C. TiO2 was reduced to Ti2O3, which is not in equilibrium phase, by low-temperature hydrogen plasma. The results of x-ray diffraction and energy dispersive x-ray analysis in experiments at 1000 °C indicate that the thermodynamical reduction potential of supercooled monatomic hydrogen is almost the same as atmospheric hydrogen gas. However, the wide Ti3O5 layer formed only in the case of the reduction at 1000 °C by supercooled monatomic hydrogen. With these experimental facts, we speculate that the reduction mechanism by nonequilibrium hydrogen consists of two steps; the releasing energy process and the relaxation process. We can explain the difference of reduction products by nonequilibrium hydrogen gas on the assumption of the rate of the relaxation process between 800 and 1000 °C.

Research of the Deflections of Beams Reinforced with BFRP Armature and Hybrid Reinforcement Using Metal and BFRP Armature

2019 ◽  
Vol 968 ◽  
pp. 301-308 ◽  
Author(s):  
Olexander I. Valovoi ◽  
Olexander Yu. Eremenko ◽  
Maksym O. Valovoi ◽  
Serhii O. Volkov
Keyword(s):  
Static Loading ◽  
Statistical Error ◽  
Load Level ◽  
Fine Aggregate ◽  
River Sand ◽  
Metal Armature ◽  
The Difference ◽  
Hybrid Reinforcement ◽  
Free Beam

It is presented the study of the beam samples reinforced with metal armature, BFRP armature and beams with hybrid reinforcement using metal and BFRP armature. Half of the tested samples of beams were manufactured on concrete with river sand, as a fine aggregate. The others were made on concrete with fractionated fine wastes of Mining and Beneficiary complex (MBC) instead of the river sand. The tests were carried out by static loading of the scheme of a single-run free beam loaded in the thirds of gear. It was established that the beams reinforced with BFRP armature and the beams with hybrid reinforcement showed an increase of strength, about 40%, compared with the beams reinforced with metal reinforcement. The deflections of the beams reinforced with BFRP armature were 315% -331% higher than the deflections of the beams reinforced with metal reinforcement and 165% -205% higher than it is allowed by standards. The use of hybrid reinforcement allowed reducing their deflections in two times compared to the beams reinforced with BFRP armature. At a load level of 60% of the destructive, the deflections of beams with hybrid reinforcement BFRP and metal armature did not exceed the maximum permissible norm. When concrete samples manufactured, the substitution of the river sand with fine fractionated wastes from the Mining and Beneficiary complex (MBC) did not affect their durability and deformability (the difference between the values according to these indicators is within the statistical error).

scholarly journals Characterisation of cubic oak specimens from the Vasa ship and recent wood by means of quasi-static loading and resonance ultrasound spectroscopy (RUS)

Holzforschung ◽  
2016 ◽  
Vol 70 (5) ◽  
pp. 457-465 ◽  
Author(s):  
Alexey Vorobyev ◽  
Olivier Arnould ◽  
Didier Laux ◽  
Roberto Longo ◽  
Nico P. van Dijk ◽  
...  
Keyword(s):  
Static Loading ◽  
Resonant Ultrasound Spectroscopy ◽  
Shear Moduli ◽  
Additional Information ◽  
Cylindrical Orthotropy ◽  
Engineering Parameters ◽  
Resonant Ultrasound ◽  
The Difference ◽  
Poisson's Ratios ◽  
Poisson’S Ratios

Abstract The cylindrical orthotropy, inherent time-dependency response, and variation between and within samples make the stiffness characterisation of wood more challenging than most other structural materials. The purpose of the present study is to compare static loading with resonant ultrasound spectroscopy (RUS) and to investigate how to combine the advantages of each of these two methods to improve the estimation of the full set of elastic parameters of a unique sample. The behavior of wood as an orthotropic mechanical material was quantified by elastic engineering parameters, i.e. Poisson’s ratios and Young’s and shear moduli. Recent and waterlogged archaeological oak impregnated with polyethylene glycol (PEG) from the Vasa warship built in 1628 was in focus. The experimental results were compared, and the difference between RUS and static loading was studied. This study contributes additional information on the influence of PEG and degradation on the elastic engineering parameters of wood. Finally, the shear moduli and Poisson’s ratios were experimentally determined for Vasa archaeological oak for the first time.

scholarly journals Synthesis and Properties of Bulk Metallic Glasses in Pd-Ni-P and Pd-Cu-P Alloys

1996 ◽  
Vol 455 ◽  
Author(s):  
Y. He ◽  
R. B. Schwarz
Keyword(s):  
Thermal Stability ◽  
Glass Transition ◽  
Metallic Glasses ◽  
Amorphous Alloys ◽  
Composition Range ◽  
Wide Composition Range ◽  
Upper Limit ◽  
Ternary Alloy Systems ◽  
The Difference ◽  
Thermal Stability Of

ABSTRACTBulk amorphous Pd-Ni-P and Pd-Cu-P alloy rods with diameters ranging from 7 to 25 mm have been synthesized over a wide composition range using a fluxing technique. For most bulk amorphous Pd-Ni-P alloys, the difference ΔT = Tx - Tg between the crystallization temperature Tx and the glass transition temperature Tg is larger than 90 K, while for bulk amorphous Pd-Cu-P alloys, ΔT varies from 27 to 73 K. Pd40Ni40P20 has the highest glass formability, and 300-gram bulk amorphous cylinders, 25 mm in diameter and 50 mm in length, can be easily produced. This size, however, is not an upper limit. The paper presents the glass formation ranges for both ternary alloy systems and data on the thermal stability of the amorphous alloys, as well as their specific heat, density, and elastic properties.

Fitting parameters for softening of wet wood under quasi static loading

Holzforschung ◽  
2004 ◽  
Vol 58 (2) ◽  
pp. 134-137 ◽  
Author(s):  
S. Hamdan ◽  
W. Dwianto ◽  
T. Morooka ◽  
M. Norimoto
Keyword(s):  
Experimental Data ◽  
Cell Wall ◽  
Static Loading ◽  
Viscoelastic Properties ◽  
Pinus Densiflora ◽  
Pinus Elliottii ◽  
Slash Pine ◽  
Radial Compression ◽  
Fitting Parameters ◽  
Compressive Tests

Abstract This work calculates the parameters that can be fitted to experimental data on compressive tests of selected softwoods and hardwoods. The woods were subjected to temperatures between 0°C and 100°C during severe radial compression. The parameters of m, c and k under the different conditions can be expressed by a constitutive equation. For most woods, parameter k (related to the Poisson's ratio) is approximately 1 except for Carpinus tschonoskii Maxim (inushide) and Aesculus turninata Blume (tochinoki). Parameter m ranges between 0.8–1 except for Pinus densiflora Seib. et Zucc. (akamatsu pine) (1.2–1.6) and Pinus elliottii Engelm (slash pine) (from 2.1 down to 1.8). Parameter c ranges between 0.2–1.5 depending on the viscoelastic properties of the cell wall for both hardwood and softwood.

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