Dissolution of powdered quartz

Moore, Guy S M; Rose, H. E.

doi:10.1038/253525b0

Cited by 13 publications

(7 citation statements)

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“…Whilst in some cases a specific cause of weakness such as a neurological disease may be identifiable, an almost inevitable contributing factor will be old age. With old age we see at best compromised physical prowess (Moore, 1975; Meltzer, 1994; Ojanen et al, 2007) and at worse a disabling loss in independence and mobility with approximately a quarter of those over 90 years of age requiring long term residential, nursing, or hospital care in the UK (Office of Fair Trading, 2005; Bajekal et al, 2006). Compromised muscle function has been identified as an independent predictor of hospitalization, disability, and death (Newman et al, 2006).…”

Section: Introductionmentioning

confidence: 99%

Sarcopenia, Dynapenia, and the Impact of Advancing Age on Human Skeletal Muscle Size and Strength; a Quantitative Review

Mitchell¹,

Williams²,

Atherton³

et al. 2012

Front. Physio.

1,009

794

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Changing demographics make it ever more important to understand the modifiable risk factors for disability and loss of independence with advancing age. For more than two decades there has been increasing interest in the role of sarcopenia, the age-related loss of muscle or lean mass, in curtailing active and healthy aging. There is now evidence to suggest that lack of strength, or dynapenia, is a more constant factor in compromised wellbeing in old age and it is apparent that the decline in muscle mass and the decline in strength can take quite different trajectories. This demands recognition of the concept of muscle quality; that is the force generating per capacity per unit cross-sectional area (CSA). An understanding of the impact of aging on skeletal muscle will require attention to both the changes in muscle size and the changes in muscle quality. The aim of this review is to present current knowledge of the decline in human muscle mass and strength with advancing age and the associated risk to health and survival and to review the underlying changes in muscle characteristics and the etiology of sarcopenia. Cross-sectional studies comparing young (18–45 years) and old (>65 years) samples show dramatic variation based on the technique used and population studied. The median of values of rate of loss reported across studies is 0.47% per year in men and 0.37% per year in women. Longitudinal studies show that in people aged 75 years, muscle mass is lost at a rate of 0.64–0.70% per year in women and 0.80–00.98% per year in men. Strength is lost more rapidly. Longitudinal studies show that at age 75 years, strength is lost at a rate of 3–4% per year in men and 2.5–3% per year in women. Studies that assessed changes in mass and strength in the same sample report a loss of strength 2–5 times faster than loss of mass. Loss of strength is a more consistent risk for disability and death than is loss of muscle mass.

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Section: Introductionmentioning

confidence: 99%

Sarcopenia, Dynapenia, and the Impact of Advancing Age on Human Skeletal Muscle Size and Strength; a Quantitative Review

Mitchell¹,

Williams²,

Atherton³

et al. 2012

Front. Physio.

1,009

794

View full text Add to dashboard Cite

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“…However the possible release of stored grinding energy involving the recrystallization of disrupted surface layers on the particles of quartz, discussed by Lindstr6m [3], must be considered. Any broadening of the e -/~ inversion should produce effects, if observeable, both on the initial DTA and subsequent DTA tests of a given sample, unless annealing reduces the strains within the particles to give a sharpening of the e-/~ peak [2].…”

mentioning

confidence: 97%

“…We reported previously [1,2] that when quartz was ground for several hundreds of hours, the disappearance of the c~-/? inversion peak on DTA was caused not by conversion of the quartz to an amorphous phase of silica, but by the formation of a microcrystalline variety of quartz with modified c~-/?…”

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confidence: 98%

Thermal effects of contamination, adsorbed water and annealing on the DTA of powdered quartz

Moore

Rose²

1979

Journal of Thermal Analysis

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During the grinding of quartz, water is adsorbed from the atmosphere, but this water gave no detectable thermal effect on DTA because it was evolved uniformly up to 1000 ~ However, in conjunction with an iron contaminant, the adsorbed water was involved in an oxidation reaction causing noticeable thermal effects for quartz powdered in a vibration mill constructed of steel parts. When powdered so finely that the ~--/3 inversion peak at 573 ~ had disappeared, annealing caused a partial redevelopment of the peak but recrystallization of disrupted quartz was too small an effect to give any detectable exothermic peak on DTA.We reported previously [1, 2] that when quartz was ground for several hundreds of hours, the disappearance of the c~-/? inversion peak on DTA was caused not by conversion of the quartz to an amorphous phase of silica, but by the formation of a microcrystalline variety of quartz with modified c~-/? inversion characteristics. A dispersion of the inversion over a range of temperature was suggested [1 ], and therefore when thermal effects were observed outside the range of temperature where the e-/~ inversion normally occurs, these were investigated and are reported here. Although the research was mainly concerned with the effect of grinding on the c~-/~ inversion, the findings reported in the present paper relate chiefly to the additional thermal effects of adsorbed water and contamination which occur during grinding.Contrasting with the c~-/? inversion which occurs on every heating, the liberation of adsorbed water or the oxidation of contaminants, if taken to completion during the first DTA run on a given sample, will not produce thrmal effects or a second or subsequent DTA test. However the possible release of stored grinding energy involving the recrystallization of disrupted surface layers on the particles of quartz, discussed by Lindstr6m [3], must be considered. Any broadening of the e -/~ inversion should produce effects, if observeable, both on the initial DTA and subsequent DTA tests of a given sample, unless annealing reduces the strains within the particles to give a sharpening of the e-/~ peak [2].The thermal effects described in this paper are often very small but, nevertheless, they are real in the sense of being reproducible, both on repeated DTA tests and, except in the case of the anomalous effects reported, from one milling test to another involving quartz from various sources. The interpretation of such small

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“…The influence of Cdl2, CrCls, and CaCl2 on hydration of 3Ca0-Si02, studied by DTA and IR (26), confirmed the strongly accelerating effect of CaCl2 and formation of Ca(OH)2. Grinding of quartz was shown to diminish the 573 °C transformation peak (293), which could be partially restored by etching with HF or fines removal by sedimentation.…”

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confidence: 99%

Thermal analysis

Murphy¹

1976

Anal. Chem.

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This review covers the major trends in thermal analysis from the previous review (303) to October 1975. In this period, several books have appeared. Volumes 2 (246) and 3 (247) of the "Atlas of Thermoanalytical Curves" have appeared and, while not in the reviewer's possession, volume 4 also is believed to be published. Books entitled "Thermal Analysis" have been published by Daniels (100) and Blazek (42). Wendlandt has issued the second edition of "Thermal Methods of Analysis" (437) and "Handbook of Commercial Scientific Instruments, Vol. 2, Thermoanalytical Techniques" (438). ''Thermal Analysis: Comparative Studies on Materials" (208) is the proceedings of a joint U.S.-Japan seminar held in Akron, Ohio, in April 1974. "Thermal Analysis", the three-volume proceedings of the Fourth ICTA held in Budapest in 1974, has been published (58) and contains 276 papers.C. B. Murphy received his B.S. and M.S. degrees from the College of the Holy Cross In 1941 and 1942, respectively. After three years of Navy duty, he returned to Holy Cross as a member of the Chemistry Department faculty. In 1952 he received his Ph.D. from Clark University. In the same year he joined American Cyanamld's Stamford Research Laboratory. After 10 years with General Electric's Advanced Technology Laboratories, he joined the Xerox Corp. as Manager of the Materials Analyses Area. He is now Manager of Toner Processing in the Xerographic Technology Dept.

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Dissolution of powdered quartz

Cited by 13 publications

References 10 publications

Sarcopenia, Dynapenia, and the Impact of Advancing Age on Human Skeletal Muscle Size and Strength; a Quantitative Review

Sarcopenia, Dynapenia, and the Impact of Advancing Age on Human Skeletal Muscle Size and Strength; a Quantitative Review

Thermal effects of contamination, adsorbed water and annealing on the DTA of powdered quartz

Thermal analysis

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