scholarly journals Chemical activation effect on the mechanical response of mortars based on dune sand

Mining Scince ◽  
2020 ◽  
Vol 27 ◽  
Author(s):  
Djelloul Ladjel ◽  
Moncef Zairi ◽  
Larbi Belagraa
Keyword(s):  
Mechanical Response ◽  
Chemical Activation ◽  
Dune Sand ◽  
Activation Effect

The Croonian Lecture, 1967: The activation of striated muscle and its mechanical response

1971 ◽  
Vol 178 (1050) ◽  
pp. 1-27 ◽  
Keyword(s):  
Mechanical Response ◽  
Striated Muscle ◽  
Motor Nerve ◽  
Chemical Activation ◽  
Small Diameter ◽  
Trunk Muscles ◽  
Muscle Fibres ◽  
Minor Importance ◽  
Main Theme ◽  
Striated Muscles

Since the end of the 1939-45 war, the task of someone trying to understand muscular contraction has become in some respects easier, and in others more difficult. On the credit side, straightforward explanations are now available—and well established—for the main events in neuromuscular transmission, propagation of the action potential, the inward spread of an activating process, chemical activation of the myofibrils, and the sliding filament process of length change. On the other side new properties, new structures and new substances have turned up which cannot yet be fitted into any comprehensive scheme. Further, we are still totally in the dark about the actual molecular processes involved even in those steps for which clear explanations are available at the electrophysiological or electronmicroscopical level. Yet another complication is the extraordinary variety of muscle types that are being discovered, even among such thoroughly studied groups of animals as amphibians and mammals. I have been repeatedly struck by cases where the investigation of muscle has been held up by a false assumption based on the supposition that different kinds of contractile materials must work in the same way. For example, it has often been argued that smooth muscle and striated muscle are essentially similar, and therefore the striations are of only minor importance; this argument was given, for example, by Bernstein (1901, p. 284). The still more general argument that the nature of the ‘contractility’ of muscle should be looked for in the supposedly simpler processes of protoplasmic movement had been the main theme of a book by Verworn (1892). This attitude was, I am sure, one of the main reasons for the almost complete disregard of the striations by physiologists and biochemists between about 1910 and 1950. Again, the elucidation of the slow motor system of certain striated muscle fibres, present in probably all vertebrates, was delayed for many years by the discovery that in mammals even the slow postural activity of limb and trunk muscles is accompanied by propagated action potentials characteristic of fast motor systems. It was widely assumed on this basis that ‘tonic’ contractions in all vertebrate striated muscles consisted of asynchronous twitches or unfused tetani in scattered motor units, and most physiologists came to disregard the numerous indications—physiological and pharmacological (Langley 1913; Sommerkamp 1928; Wachholder & von Ledebur 1930) as well as histological (see Krüger (1952) for references both to his own work in the thirties and to other work)—of the existence of a second, slow, system in skeletal muscles of the frog. The very slow contractions elicited in the familiar gastrocnemius muscle of the frog by stimulating small-diameter motor-nerve fibres (Tasaki & Kano 1942; Tasaki & Mizutani 1944; Tasaki & Tsukagoshi 1944) came as a complete surprise to most physiologists, and received little attention until the matter was taken up by Kufiler and his colleagues (e.g. Kuffler & Vaughan Williams 1953). The astonishing range of structural diversity that becomes apparent when one looks at the arthropods as well as the vertebrates has recently been emphasized by Hoyle (1967).

Physical and Chemical Activation Effect on Activated Carbon Prepared from Local Pineapple Waste

2014 ◽  
Vol 699 ◽  
pp. 87-92 ◽  
Author(s):  
Abdul Rahim Yacob ◽  
Adlina Azmi ◽  
Mohd Khairul Asyraf Amat Mustajab
Keyword(s):  
Activated Carbon ◽  
Phosphoric Acid ◽  
Surface Area ◽  
Activated Carbons ◽  
Chemical Activation ◽  
Bet Surface Area ◽  
Activation Effect ◽  
Pineapple Waste ◽  
Pineapple Peel ◽  
Physical And Chemical

The characteristics and quality of activated carbons prepared depending on the chemical and physical properties of the starting materials and the activation method used. In this study, activated carbon prepared using pineapple waste. Three parts of pineapple waste which comprises of peel, crown and leaf were studied. For comparison activated carbon were prepared by both physical and chemical activation respectively. Three types of chemicals were used, phosphoric acid (H3PO4), sulphuric acid (H2SO4), and potassium hydroxide (KOH). The preparation includes carbonization at 200°C and activation at the 400°C using muffle furnace. The chemical characterization of the activated carbon was carried out using Thermogravimetric analysis (TGA), Nitrogen gas adsorption analysis and Fourier transform infrared (FTIR). The highest BET surface area was achieved when the pineapple peel soaked in 20% phosphoric acid with a surface area of 1115 m2g-1. FTIR analysis indicates that the reacted pineapple waste successfully converted into activated carbons.

Study on the Preparation of Activated Carbon from Corncobs

2013 ◽  
Vol 634-638 ◽  
pp. 1398-1403
Author(s):  
Jun Han Li ◽  
Shao Li Yang ◽  
Ning Sun ◽  
Lan Ma
Keyword(s):  
Activated Carbon ◽  
Orthogonal Experiment ◽  
Chemical Activation ◽  
Activation Process ◽  
Activator Concentration ◽  
Activation Effect ◽  
Activation Temperature ◽  
Impregnation Ratio ◽  
The Impact ◽  
Better Than

The impact of activator varieties on the activation effect in preparing activated carbon with corncob adopting chemical activation process were researched in this paper, the results showed that phosphoric acid as the activator was much better than potassium hydroxide and zinc chloride. It was deduced from the orthogonal experiment results that the impact of activation temperature on the activation effect is the greatest, impregnation ratio takes the second place, and the activator concentration the least. Suitable parameters of activation process were obtained: when the activator concentration is 50%, activation temperature 500°C, impregnation ratio 2.7:1, the iodine value of activated carbon is 822.08mg/g.

scholarly journals Influence of Mechanochemical Activation of Concrete Components on the Properties of Vibro-Centrifugated Heavy Concrete

2021 ◽  
Vol 11 (22) ◽  
pp. 10647
Author(s):  
Evgenii M. Shcherban’ ◽  
Sergey A. Stel’makh ◽  
Alexey Beskopylny ◽  
Levon R. Mailyan ◽  
Besarion Meskhi
Keyword(s):  
Mechanochemical Activation ◽  
Chemical Activation ◽  
Energy Resource ◽  
Concrete Mixture ◽  
Double Complex ◽  
Activation Effect ◽  
Study Results ◽  
Concrete Production ◽  
Production Techniques ◽  
New Material

One of the crucial problems in current construction is energy, resource, and material efficient technologies in both industrial and civil engineering, associated with new material manufacturing and building construction. This article is devoted to developing comprehensive technology for activation effects on concrete made by various production techniques: vibration, centrifugation, and vibro-centrifugation. The possibility of a significant improvement in the microstructure of concrete and obtaining materials with increased specified characteristics, depending on its manufacturing technology, were studied during the complex activation effect exposed to this concrete and its components. Chemical activation of water and mechanical activation of cement were considered. The urgency and prospects of double, complex mechanochemical activation of concrete mixture components were substantiated. It was proven that the complex mechanochemical activation of the concrete mixture components gives a synergistic effect in obtaining concrete composition with an improved structure and improved characteristics. Furthermore, the relationship between concrete production technology and the technology of activation of its components was established. It was revealed that the most effective is the complex mechanochemical activation of vibro-centrifuged concrete, which gives an increase in strength up to 30%. The study results indicate a further direction of development associated with an increase in variatropic characteristics using both prescription and technological factors.

scholarly journals ADSORPTION OF NICKEL IN NICKEL SULPHATE SOLUTION (NISO4) BY LAPINDO MUD

2017 ◽  
Vol 6 (1) ◽  
pp. 39-44
Author(s):  
Khalimatus Sa'diyah ◽  
Muchamad Syarwani ◽  
Sigit Hadiantoro
Keyword(s):  
Chemical Activation ◽  
Nickel Sulfate ◽  
Sulfate Solution ◽  
Nickel Concentration ◽  
Physical Activation ◽  
Activation Process ◽  
Activation Effect ◽  
Calcination Process ◽  
Before And After

This research has been carried out to produce adsorbent from Lapindo mud through various activation process, to adsorb nickel from nickel sulfate solution. Several investigations were performed in this research such as characterization of Lapindo mud before and after activation, effect of physical, chemical and chemico-physical activation to Si/Al ratio and determine the most effective method to produce adsorbent with high adsorption rate. Lapindo mud in this research was prepared through several methods such as without activation, calcination at 500 C for 3 hours, chemical activation with 6 N HCl under reflux for 6 hours, chemical activation with 6 N NaOH under reflux for 6 hours, chemical activation with 6 N HCl under reflux followed by calcination process and the last treatment is chemical activation with 6 N NaOH under reflux followed by calcination process. The object of this research is the Lapindo mud adsorbent ability to adsorb Ni from NiSO4 solution. While activation methods and nickel concentration in this become independent variable. The reduction of nickel concentration efficiency is determined by the nickel concentration before and after adsorption process. The Si/Al ratio of Lapindo mud before activation process was 3.01 and it increase as the mud is activated. The highest Si/Al ratio was found at activation using HCl which is 7.85. Chemical activation using NaOH was found to be the best method to create the adsorbent with adsorption capacity 98.3%.

Properties of Alkali-Activated Waste Glass-Cement Cementitious Materials

2018 ◽  
Vol 926 ◽  
pp. 134-139 ◽  
Author(s):  
Wen Juan Yao ◽  
Lei Fan ◽  
Guang Yan Liu
Keyword(s):  
Glass Powder ◽  
Chemical Activation ◽  
Cementitious Materials ◽  
Waste Glass ◽  
Curing Time ◽  
Hydration Products ◽  
Activation Effect ◽  
Engineering Construction ◽  
Pozzolanic Reactivity ◽  
Waste Glass Powder

The hydration products, microstructure and development principle of intensity of cement-glass powder cementitious materials acted in alkali and activation effect of chemical activation on waste glass powder were investigated. The principle of intensity and effect of curing time was analyzed by changing alkali type, content of alkali, incorporation of glass powder, incorporation method of activators and other factor. The result shows that: sodium carbonate and sodium silicate can single stimulate activity of glass powder under a certain condition, the activated effect of combined admixture is superior to the effect on single-doped activator, under the action of an excitation agent, surface hydrolysis of glass powder takes place on the glass body first and the hydration products occurs, The pozzolanic reactivity of glass powder increases gradually and generated a larger amount of hydration products，which has lapped and interlocked growth between each other，and form the compact hardened matrix. In addiation, the shorting of curing time is used by activator, the result may be lead to initial curing and against in engineering construction.

Utilization of walnut shell as a feedstock for preparing high surface area activated carbon by microwave induced activation: effect of activation agents

2016 ◽  
Vol 5 (1) ◽  
Author(s):  
Hongying Xia ◽  
Song Cheng ◽  
Libo Zhang ◽  
Jinhui Peng
Keyword(s):  
Activated Carbon ◽  
Microwave Heating ◽  
Surface Area ◽  
Chemical Activation ◽  
High Surface ◽  
High Surface Area ◽  
Walnut Shell ◽  
Activation Effect

AbstractThe present work attempts to convert walnut shell into a high surface area activated carbon by microwave heating and chemical activation. Different activation agents such as KOH, NaOH, K

Porosity of carbons obtained by chemical activation: effect of the nature of the alkaline carbonates

Carbon ◽  
2002 ◽  
Vol 40 (7) ◽  
pp. 1140-1143 ◽  
Author(s):  
A Addoun ◽  
J Dentzer ◽  
P Ehrburger
Keyword(s):  
Chemical Activation ◽  
Activation Effect

Comparison of Substructures Between Uniaxial and Biaxial Deformation in 1100-0 Aluminum

1981 ◽  
Vol 39 ◽  
pp. 52-53
Author(s):  
D. L. Rohr ◽  
S. S. Hecker
Keyword(s):  
Plastic Strain ◽  
Cell Walls ◽  
Room Temperature ◽  
Mechanical Response ◽  
Biaxial Tension ◽  
Initial Deformation ◽  
Uniaxial Deformation ◽  
Biaxial Deformation ◽  
Stress States ◽  
Comprehensive Study

As part of a comprehensive study of microstructural and mechanical response of metals to uniaxial and biaxial deformations, the development of substructure in 1100 A1 has been studied over a range of plastic strain for two stress states.Specimens of 1100 aluminum annealed at 350 C were tested in uniaxial (UT) and balanced biaxial tension (BBT) at room temperature to different strain levels. The biaxial specimens were produced by the in-plane punch stretching technique. Areas of known strain levels were prepared for TEM by lapping followed by jet electropolishing. All specimens were examined in a JEOL 200B run at 150 and 200 kV within 24 to 36 hours after testing.The development of the substructure with deformation is shown in Fig. 1 for both stress states. Initial deformation produces dislocation tangles, which form cell walls by 10% uniaxial deformation, and start to recover to form subgrains by 25%. The results of several hundred measurements of cell/subgrain sizes by a linear intercept technique are presented in Table I.

Construction of plastic contact deformation maps on ceramics: a case study on aluminum nitride

1996 ◽  
Vol 54 ◽  
pp. 636-637
Author(s):  
D. L. Callahan
Keyword(s):  
Plastic Deformation ◽  
Aluminum Nitride ◽  
Mechanical Response ◽  
Three Dimensional ◽  
Bright Field Image ◽  
Perfectly Plastic ◽  
Contrast Analysis ◽  
Deformation Patterns

Modern polishing, precision machining and microindentation techniques allow the processing and mechanical characterization of ceramics at nanometric scales and within entirely plastic deformation regimes. The mechanical response of most ceramics to such highly constrained contact is not predictable from macroscopic properties and the microstructural deformation patterns have proven difficult to characterize by the application of any individual technique. In this study, TEM techniques of contrast analysis and CBED are combined with stereographic analysis to construct a three-dimensional microstructure deformation map of the surface of a perfectly plastic microindentation on macroscopically brittle aluminum nitride.The bright field image in Figure 1 shows a lg Vickers microindentation contained within a single AlN grain far from any boundaries. High densities of dislocations are evident, particularly near facet edges but are not individually resolvable. The prominent bend contours also indicate the severity of plastic deformation. Figure 2 is a selected area diffraction pattern covering the entire indentation area.

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