scholarly journals Reaction of quartz glass in lithium-containing alkaline solutions with or without Ca

2018 ◽  
Vol 5 (9) ◽  
pp. 180797
Author(s):  
Baofu Zhou ◽  
Zhongyang Mao ◽  
Min Deng
Keyword(s):  
Quartz Glass ◽  
Alkaline Solution ◽  
Alkali Silica Reaction ◽  
Alkaline Solutions ◽  
Lithium Ions ◽  
Exact Role ◽  
Alkali Ions ◽  
Immersion Experiment ◽  
Production Layer

The exact role of lithium ions (Li + ) in controlling alkali–silica reaction is still unclear. Thus, the effects of Li + on the reaction between reactive silica (quartz glass) and hydroxyl in alkaline solution with or without Ca were investigated by quartz glass powder or slice immersion experiments. When quartz glass was immersed in lithium-containing alkaline solutions, only Li 2 SiO 3 was produced with the absence of Ca, but Li 2 SiO 3 and calcium silicate hydrate (CSH) were formed with the presence of Ca. The quartz glass slice immersion experiment indicated that the mass loss of quartz slices was less than 1% only when Ca was present in the lithium-containing alkaline solution. This was because a dense, low-porosity and strongly bonded production layer mainly composed of CSH and Li 2 SiO 3 crystals was formed on the glass surface and served as a barrier against the diffusion of OH − and alkali ions to the substrate glass.

Porosity/Diffusivity And Alkali-Silica Reaction

1988 ◽  
Vol 137 ◽  
Author(s):  
Micheline Moranville-Resocurd
Keyword(s):  
Chemical Processes ◽  
Alkali Silica Reaction ◽  
Physical Processes ◽  
Alkali Ions ◽  
Water Imbibition ◽  
Corrosion Of Steel ◽  
Physical And Chemical ◽  
Secondary Chemical ◽  
And Diffusion

AbstractPhysical and chemical processes are responsible for the alkali-silica reaction in concrete. Physical processes include (i) migration of hydroxyl and alkali ions (ii) swelling by water imbibition of the alkali-silica gel produced, (iii) development of cracks. Chemical processes involve (i) neutralisation of acidic silanol groups and attack of siloxane bridges, both by OH- ions (ii) formation of an alkali silicate. These reactions result in a breakdown in the silica structure and diffusion of some silicate and impregnate the cement paste filling the capillary pores. The increase in permeability due to the opening and progression of cracks facilitates secondary chemical deteriorations like the formation of ettrinqite, carbonation and corrosion of steel reinforcement. Recent studies have emphasized the role of Ca(OH)2 preventing the dissolution or miqration of freed silica out of the structure. Only the removal of Ca(OH)2 is able to stop the expansion of concrete.The paper will present some new interpretations of alkali-silica reaction related to the diffusivity of various ions from the pore solution.

Chemical deposition of hard composite coatings Ni–Cu–P–Cr2O3

2020 ◽  
pp. 179-181
Author(s):  
A.A. Abrashov A.A. ◽  
E.G. Vinokurov ◽  
M.A. Egupova ◽  
V.D. Skopintsev
Keyword(s):  
Chromium Oxide ◽  
Alkaline Solution ◽  
Composite Coatings ◽  
Chemical Deposition ◽  
Alkaline Solutions ◽  
Functional Surface ◽  
Heat Treated ◽  
Weakly Acid Solution ◽  
Coating Composition ◽  
Weakly Acidic Solution

The technological (deposition rate, coating composition) and functional (surface roughness, microhardness) characteristics of chemical composite coatings Ni—Cu—P—Cr2O3 obtained from weakly acidic and slightly alkaline solutions are compared. It is shown that coatings deposited from slightly alkaline solution contain slightly less phosphorus and chromium oxide than coatings deposited from weakly acid solution (2...3 % wt. phosphorus and up to 3.4 % wt. chromium oxide), formed at higher rate (24...25 microns per 1 hour of deposition at temperature of 80 °C), are characte rized by lower roughness and increased microhardness. The Vickers microhardness at 0.05 N load of composite coatings obtained from slightly alkaline solution and heat-treated at 400 °C for 1 hour is 13.5...15.2 GPa, which is higher than values for coatings deposited made of weakly acidic solution. The maximum microhardness of coatings is achieved at concentration 20 g/l of Cr2O3 particles. The technology of chemical deposition of Ni—Cu—P—Cr2O3 coatings formed in slightly alkaline solution is promising for obtaining of materials with increased hardness and wear resistance.

scholarly journals The Enigma of Eosinophil Degranulation

2021 ◽  
Vol 22 (13) ◽  
pp. 7091
Author(s):  
Timothée Fettrelet ◽  
Lea Gigon ◽  
Alexander Karaulov ◽  
Shida Yousefi ◽  
Hans-Uwe Simon
Keyword(s):  
Blood Cells ◽  
Inflammatory Diseases ◽  
White Blood Cells ◽  
Exact Role ◽  
Effector Cells ◽  
Effector Functions ◽  
Cytotoxic Effector ◽  
Eosinophil Degranulation

Eosinophils are specialized white blood cells, which are involved in the pathology of diverse allergic and nonallergic inflammatory diseases. Eosinophils are traditionally known as cytotoxic effector cells but have been suggested to additionally play a role in immunomodulation and maintenance of homeostasis. The exact role of these granule-containing leukocytes in health and diseases is still a matter of debate. Degranulation is one of the key effector functions of eosinophils in response to diverse stimuli. The different degranulation patterns occurring in eosinophils (piecemeal degranulation, exocytosis and cytolysis) have been extensively studied in the last few years. However, the exact mechanism of the diverse degranulation types remains unknown and is still under investigation. In this review, we focus on recent findings and highlight the diversity of stimulation and methods used to evaluate eosinophil degranulation.

scholarly journals Flammable gases produced by TiO2 nanoparticles under magnetic stirring in water

Friction ◽  
2021 ◽  
Author(s):  
Pengcheng Li ◽  
Chongyang Tang ◽  
Xiangheng Xiao ◽  
Yanmin Jia ◽  
Wanping Chen
Keyword(s):  
Tio2 Nanoparticles ◽  
Quartz Glass ◽  
Dye Degradation ◽  
Mechanical Energy ◽  
Chemical Energy ◽  
Magnetic Stirring ◽  
Catalytic Role ◽  
Nanostructured Semiconductors

AbstractThe friction between nanomaterials and Teflon magnetic stirring rods has recently drawn much attention for its role in dye degradation by magnetic stirring in dark. Presently the friction between TiO2 nanoparticles and magnetic stirring rods in water has been deliberately enhanced and explored. As much as 1.00 g TiO2 nanoparticles were dispersed in 50 mL water in 100 mL quartz glass reactor, which got gas-closed with about 50 mL air and a Teflon magnetic stirring rod in it. The suspension in the reactor was magnetically stirred in dark. Flammable gases of 22.00 ppm CO, 2.45 ppm CH4, and 0.75 ppm H2 were surprisingly observed after 50 h of magnetic stirring. For reference, only 1.78 ppm CO, 2.17 ppm CH4, and 0.33 ppm H2 were obtained after the same time of magnetic stirring without TiO2 nanoparticles. Four magnetic stirring rods were simultaneously employed to further enhance the stirring, and as much as 30.04 ppm CO, 2.61 ppm CH4, and 8.98 ppm H2 were produced after 50 h of magnetic stirring. A mechanism for the catalytic role of TiO2 nanoparticles in producing the flammable gases is established, in which mechanical energy is absorbed through friction by TiO2 nanoparticles and converted into chemical energy for the reduction of CO2 and H2O. This finding clearly demonstrates a great potential for nanostructured semiconductors to utilize mechanical energy through friction for the production of flammable gases.

scholarly journals Mechanisms of passivation and chloride-induced corrosion of mild steel in sulfide-containing alkaline solutions

2021 ◽  
Author(s):  
Shishir Mundra ◽  
John L. Provis
Keyword(s):  
Mild Steel ◽  
Surface Film ◽  
Critical Role ◽  
Chloride Concentration ◽  
Alkaline Solutions ◽  
Sulfide Concentration ◽  
Chloride Induced Corrosion ◽  
Alkaline Sulfide ◽  
High Sulfide

AbstractThe pore fluid within many concretes is highly alkaline and rich in reduced sulfur species, but the influence of such alkaline-sulfide solutions on the surface film formed on steel reinforcement is poorly understood. This study investigates the critical role of HS− in defining mild steel passivation chemistry. The surface film formed on the steel in alkaline-sulfide solutions contains Fe(OH)2 and Fe–S complexes, and the critical chloride concentration to induce corrosion increases at high sulfide concentration. However, this behavior is dependent on the duration of exposure of the steel to the electrolyte, and the nature of the sulfidic surface layer.

Considering Spirituality in Occupational Therapy Practice

1994 ◽  
Vol 61 (2) ◽  
pp. 95-101 ◽  
Author(s):  
Mary Egan ◽  
M. Denise Delaat
Keyword(s):  
Health Care ◽  
Clinical Practice ◽  
Occupational Therapy ◽  
Occupational Therapists ◽  
Occupational Performance ◽  
Exact Role ◽  
Therapy Guidelines

Despite its prominent place in the Occupational Therapy Guidelines for client-centred practice, the exact role of spirituality in clinical practice has been difficult to delineate. In this paper current concepts of spirituality are outlined and ways in which these concepts have been applied in health care are described. To illustrate these spiritual concepts, the experiences of individuals whom the authors have met in their clinical practice are outlined in a series of vignettes. Finally, a revision of the model of occupational performance which enhances consideration of spirituality in occupational therapy practice is proposed, and some guidelines for occupational therapists wishing to incorporate spiritual concerns in therapy are suggested.

scholarly journals Ancient Pneumatics Transformed during the Early Modern Period

Nuncius ◽  
2014 ◽  
Vol 29 (1) ◽  
pp. 127-173 ◽  
Author(s):  
Matteo Valleriani
Keyword(s):  
Sixteenth Century ◽  
Early Modern ◽  
Early Modern Period ◽  
Logical Structure ◽  
Exact Role ◽  
Ancient Technology ◽  
Ancient Science ◽  
Modern Period ◽  
Natural Philosophers

The paper aims to show how sixteenth century hydraulic and pneumatic engineers appropriated ancient science and technology – codified in the text of Hero of Alexandria’s Pneumatics – to enter into scientific discourse, for instance, with natural philosophers. They drew on the logical structure, content and narrative style passed down from antiquity to generate and codify their own theoretical approach and to document their new technological achievements. They did so by using the form of commented and enlarged editions, just as Aristotelian natural philosophers had been doing for centuries. The argument aims to detail the exact role of ancient science and the process of transformation it underwent during the early modern period. In particular, it aims to show how pneumatic engineers first tested the ancient technology codified by Hero while carrying out their own practical activities. Once these tests were successfully concluded, in the spirit of early modern humanism they finally presented these activities as being associated with the work of their discipline’s most authoritative author, Hero of Alexandria, whose technology was tested during the construction of the hydraulic and pneumatic system of the garden of Pratolino.

The role of iron in the preparation and oxygen reduction reaction activity of nitrogen-doped carbon

2015 ◽  
Vol 51 (12) ◽  
pp. 2450-2453 ◽  
Author(s):  
Dae-Soo Yang ◽  
Min Young Song ◽  
Kiran Pal Singh ◽  
Jong-Sung Yu
Keyword(s):  
Oxygen Reduction Reaction ◽  
Oxygen Reduction ◽  
Carbon Sources ◽  
Reduction Reaction ◽  
Acidic Media ◽  
Oxygen Reduction Reaction Activity ◽  
Exact Role ◽  
Ordered Mesoporous ◽  
Nitrogen Doped Carbon

The exact role of iron in catalyzing oxygen reduction reaction in both alkaline and acidic media is portrayed with unique platelet ordered mesoporous carbon prepared using Fe-phthalocyanine as iron, nitrogen and carbon sources.

scholarly journals Role of viruses in oral squamous cell carcinoma

2012 ◽  
Vol 6 (2) ◽  
pp. 21 ◽  
Author(s):  
Rashmi Metgud ◽  
Madhusudan Astekar ◽  
Meenal Verma ◽  
Ashish Sharma
Keyword(s):  
Risk Factors ◽  
Squamous Cell Carcinoma ◽  
Oral Squamous Cell Carcinoma ◽  
Cell Carcinoma ◽  
Genetic Susceptibility ◽  
Squamous Cell ◽  
Oncogenic Viruses ◽  
Exact Role ◽  
Carcinogenic Effects

The etiology of oral squamous cell carcinoma (OSCC) is complex and involves many factors. The most clearly defined risk factors are smoking and alcohol, which substantially increase the risk of oral SCC. However, despite this clear association, a substantial proportion of patients develop OSCC without exposure to them, emphasizing the role of other risk factors such as genetic susceptibility and oncogenic viruses. Some viruses are strongly associated with OSCC while the association of others is less frequent and may depend on co-factors for their carcinogenic effects. Therefore, the exact role of viruses must be evaluated with care in order to improve the diagnosis and treatment of OSCC.

Sir Charles Dilke and the British Intervention In Egypt, 1882: decision making In a nineteenth-century cabinet

1976 ◽  
Vol 2 (3) ◽  
pp. 231-245 ◽  
Author(s):  
M. E. Chamberlain
Keyword(s):  
Nineteenth Century ◽  
Decision Making ◽  
British Imperialism ◽  
Exact Role ◽  
The Unconscious ◽  
William Gladstone ◽  
Two Generations ◽  
Liberal Government

“There's Dilke that has done it all”, remarked Wilfrid Scawen Blunt to Lord Blandford as they watched Dilke walk down Piccadilly one day in July 1882.1 The “it” was the British intervention in Egypt which entangled Britain in Egyptian affairs for two generations. More soberly, Louis Mallet, the Permanent Under-Secretary at the India Office, wrote to Evelyn Baring a year later that the Liberal government of William Gladstone had made themselves “the unconscious, and some of them (not all) the unwilling instruments of a policy from which Lord Beaconsfield and Lord Salisbury would have shrunk, and which is big with future disaster”. “Dilke and Chamberlain” he wrote, “I consider mainly responsible for the Egyptian war.” In The Trouble Makers, A. J. P. Taylor came to the conclusion, “The occupation of Egypt in 1882 marked Gladstone's decisive breach with Radicalism. Indeed it ruined Radicalism for more than a generation. It began modern British Imperialism…”. How ironic if the ruin of British radicalism was brought about by the two leading radicals of Gladstone's predominantly Whig administration. What do the Dilke and Chamberlain papers among others reveal about the exact role of the two men in the crisis ?

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