Extraction of Metastable Icosahedral Quasicrystalline Nanoparticles from Zirconium and Hafnium Based Metallic Glasses

Solvent extraction and separation of hafnium from zirconium using Ionquest

industries, its nuclear properties in the pure metallic form make it highly desirable for nuclear applications. Zr is highly corrosion resistant and has a high melting point (2128 K) with a low thermal neutron absorption cross-section of Zr T = 0.18 b, which is significantly smaller than that of hafnium Hf T =115 b) (Speer, 1982), an element that coexists with Zr in nature. This makes Zr ideal ...

Icosahedral ordering in supercooled liquids and metallic glasses

Harmonic behavior of metallic glasses up to the metastable melt.

In two amorphous alloys ZrTiCuNiBe and ZrAlNiCu coherent neutron scattering has been measured over five decades in energy, including measurements in the metastable melt of a metallic alloy more than 80 K above Tg . In the vibrational spectra a pronounced ‘‘boson’’ peak is found: Even in crystallized samples the density of states exceeds the Debye v model, and in the amorphous state low-frequenc...

Overheating threshold and its effect on time–temperature-transformation diagrams of zirconium based bulk metallic glasses

A pronounced effect of overheating is observed on the crystallization behavior for the three zirconium-based bulk metallic glasses: Zr41.2Ti13.8Cu12.5Ni10Be22.5 , Zr57Cu15.4Ni12.6Al10Nb5 , and Zr52.5Cu17.9Ni14.6Al10Ti5 . A threshold overheating temperature is found for each of the three alloys, above which there is a drastic increase in the undercooling level and the crystallization times. Time...

extraction and acetylation of purified trypsin from bovin pancreas and study of some its physico-chemical properties

آنزیم تریپسین در شرایط قلیایی ناپایدار می باشد .و فعالیت پروتئولیتیکی تریپسین منجربه خود هضمی آن در جایگاههای خاصی می گردد. بنابر این آنزیمی با ناپایداری بالا محسوب میگردد. در سالهای اخیر موفق شدند که با ایجاد تغیرات شیمیایی با اضافه کردن فلزات خاص ، کلسیم و یا عمل استیلاسیون منجر به افزایش پایداری آنزیم تریپسین گردند. مطالعات در حال حاضر نشان می دهد که تریپسین استیله شده فعالیت آنزیمی خود را ...