نتایج جستجو برای: hmf
تعداد نتایج: 984 فیلتر نتایج به سال:
A review of new developments in theoretical and experimental electronic structure investigations of half-metallic ferromagnets (HMF) is presented. Being semiconductors for one spin projection and metals for another ones, these substances are promising magnetic materials for applications in spintronics (i.e., spin-dependent electronics). Classification of HMF by the peculiarities of their electr...
Observational studies have reported solar magnetic modulation of terrestrial lightning on a range of time scales, from days to decades. The proposed mechanism is two-step: lightning rates vary with galactic cosmic ray (GCR) flux incident on Earth, either via changes in atmospheric conductivity and/or direct triggering of lightning. GCR flux is, in turn, primarily controlled by the heliospheric ...
5-Hydroxymethylfurfural (5-HMF), which is derived from numerous industrial biomass resources, has attracted attention in recent years due to its potential as a building block. In this paper, a range of heteropolyacid salts had been investigated for the dehydration of fructose to 5-HMF. CePW12O40 demonstrated the best catalytic activity. Effects of fructose concentration, reaction temperature an...
In the near future, the world will need to gradually replace the use of fossil resources for energy consumption and platform chemicals with other resources. For the energy issue, the ongoing approach is based mainly on a diversity of resources, such as nuclear, coal, hydraulic and wind power, photovoltaics, and biofuels. In the case of chemical platforms, probably the major resource will be bas...
background and objectives: furfural (f) and hydroxymethyl furfural (hmf) are cyclic aldehydes, which are formed during the heat processing of foods. these chemical contaminants have received much attention due to their suspected health hazards and heat damage indicators. the aim of the present study was extraction and determination of f and hmf in baby-foods using dispersive liquid-liquid micro...
Primary cutaneous lymphomas (PCL) are rare in pediatrics. Mycosis fungoides (MF) is the most frequent PCL diagnosed in childhood. There are various clinical variants of MF, including the hypopigmented MF (HMF). We present a 5-year-old boy with an 18-month history of progressive, generalized, nonpruritic hypopigmented lesions with central lacy erythema. He had no improvement with emollients. Ski...
A convenient system for producing 5-hydroxymethylfurfural (HMF) through dehydration of carbohydrates by microwave heating in the presence of ZnCl2 was studied. The use of ZnCl2 gave higher selectivity than other metal salts in the conversion of glucose. With ZnCl2 as catalyst, sucrose could be utilized effectively. Under the conditions of microwave irradiation (300 W, 8 min), HMF yields were 54...
5-hydroxymethylfurfural (5-hmf) is known as an indicator of quality deterioration in a wide range of foods. the current study covered 70 samples taken from domestically produced foods and drinks available on the iranian markets (including honey, jam, fruit cakes tomato paste, ketchup, syrup, fruit juice, canned fruit, uht milk, instant coffee and jelly powder). hmf levels were determined using ...
the conversion of the cellulose into 5-hmf would experience three steps, cellulose to glycose, glycose to fructose and fructose to 5-hmf. chloride ion can break down the hydrogen bond in cellucose, chromium can catalyze the isomerization of glycose to fructose, and the high temperature is helpful to cyclohydration of fructose to 5-hmf. in this paper, the sawdust has been directly degraded into ...
The one-pot acid-catalysed conversion of mono/di/polysaccharides (inulin, xylan, cellobiose, sucrose, glucose, fructose, xylose) into 2-furfuraldehyde (FUR) or 5-hydroxymethylfurfural (HMF) in the presence of aluminium-containing mesoporous TUD-1 (denoted as Al-TUD-1, Si/Al = 21), at 170 degrees C was investigated. Xylose gave 60% FUR yield after 6 h reaction; hexose-based mono/disaccharides ga...
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