New insight into kinetics behavor of the structural formation process in Agar gelation

A time-resolved experimental study on the kinetics and relaxation of the structural formation process in gelling Agar-water solutions was carried out using our custom-built torsion resonator. The study was based on measurements of three naturally cooled solutions with agar concentrations of 0.75%, 1.0% and 2.0% w/w. It was found that the natural-cooling agar gelation process could be divided into three stages, sol stage (Stage I), gelation zone (Stage II) and gel stage (Stage III), based on the time/temperature evolutions of the structural development rate (SDR). An interesting fluctuant decaying behavior of SDR was observed in Stage II and III, indicative of a sum of multiple relaxation processes and well described by a multiple-order Gaussisn-like equation: . More interestingly, the temperature dependences of the fitted values of Wn in Stage II and Stage III were found to follow the different Arrhenius laws, with different activation energies of EaII= 39-74 KJ/mol and EaIII~7.0 KJ/mol. The two different Arrhenius-like behaviors respectively suggest that dispersions in Stage II be attributed to the relaxation of the self-assembly of agar molecules or the growth of junction zones en route to gelation, in which the formation or fission of hydrogen bonding interactions plays an important role; and that dispersions in Stage III be attributed to the relaxation dynamics of water released from various size domains close to the domain of the viscous flow of water during the syneresis process.Comment: 24 pages, 4 figures, 1 tabl

Characteristics of Different Systems for the Solar Drying of Crops

Solar dryers are used to enable the preservation of agricultural crops, food processing industries for dehydration of fruits and vegetables, fish and meat drying, dairy industries for production of milk powder, seasoning of wood and timber, textile industries for drying of textile materials. The fundamental concepts and contexts of their use to dry crops is discussed in the chapter. It is shown that solar drying is the outcome of complex interactions particular between the intensity and duration of solar energy, the prevailing ambient relative humidity and temperature, the characteristics of the particular crop and its pre-preparation and the design and operation of the solar dryer

Konya asarı atika müzesinde Mevlana Celaleddini Ruminin sandukası.

Donated by Klaus KreiserReprinted from : Türk Tarih, Arkeoloji ve Etnografya Dergisi, III, 1936

Studies on goat hydroxyapatite/commercial inert glass biocomposites

In this study, mechanical properties and microstructural analysis of goat-derived hydroxyapatite/commercial inert glass biocomposites are considered in the temperature range between 1000 and 1300 °C. The results indicate that the best values of maximum compressive strength and microhardness are achieved in the samples sintered at 1200 °C for the glass in the weight of 5 and 10%. Moreover, above 1000 °C, decomposition of hydroxyapatite and new phase formations such as whitlockite and silicocarnotite play also a major role in the hardness and strength for goat hydroxyapatite/commercial inert glass biocomposites. © 2018, Australian Ceramic Society

Cookers for solar homes

Means of piping solar energy into kitchens were investigated. Two different solar cookers utilising the heat-pipe principle were designed, constructed and tested. A cooker utilising an east-west line focusing collector, designated Mecca-1, was developed for this purpose. The second cooker was a flat-plate heat-pipe cooker, Mecca-2. A single heat pipe in each cooker absorbed the energy at the collector, transported it into the kitchen and delivered it to an insulated oven at the condenser end. Various heating and boiling experiments conducted on the two cookers demonstrated the feasibility of the concept. It was found that the Mecca-2 cooker with triple glazing had a utilisation efficiency of up to 19 per cent and could boil 1 litre of water in 27 min for a solar insolation of 900 W/m2.