A comparative study of drying techniques on the morphology of porous silica gels synthesized via sol-gel process

The effect of drying techniques on the microstructure,morphology and pore structure of porous silica gels was studied in the paper.The gels were prepared by using sol-gel process and different drying routes:freeze-drying (FD),low pressure drying (LPD),high temperature drying (HTD) and chemical modification & ambient drying (CMD) techniques.Observation under pore distribution and structural properties showed that CMD technique leads to homogenous mesoporous silica material with specific surface area of 745 m2/g,and the average pore size around 20 nm,while LPD and HTD result in loosely packed particles with non-isotropic aggregation pattern.The specific surface areas of LPD and HTD samples are 419 and 513 m2/g respectively,and the pore size distribution of the samples are observed distributing widely in range of 10-100 nm.Freeze drying method is a new but prospective way to prepare mesoporous silica.The specific area of FD sample is around 500 m2/g.By the comparison for the properties of the gels,this paper wants to induce a further interest in finding a proper method to synthesize the porous silica gels for low price use.

Comparison of the Performance of Three Cocoa Bean Drying Techniques in Bafia, Southwest Region, Cameroon

This research compares the performance of a wood-fuelled oven,a greenhouse solar dryer and open sun drying techniques for drying of fermented cocoa beans,under the same weather conditions.The tests were implemented in Bafia,in the Southwest Region of Cameroon,during the month of November 2017.Performance in drying time(number of days)and quality of the resulting beans were measured(determined using sensory measurements,sight,smell and taste).Data were also collected on the progression of weight and moisture loss in the beans during the drying process,and the ambient temperatures and relative humidity levels of the environment.Also,solar radiation levels were measured for the greenhouse solar dryer and open sun drying techniques.Results showed that during dry weather conditions the wood-fuelled oven was the fastest drying method(1 day),followed by open sun drying(4 days)and the greenhouse solar dryer(5 days).The quality of beans produced through open sun drying and in the greenhouse solar dryer had a good colour,and a pleasant chocolate smell and taste.However,the beans from the wood-fuelled oven had an overly dark colour and their smell and taste were smoky due to contamination by smoke from the oven.

Atmospheric Drying UHMWPE Membranes via Multiple Stage Extractant Exchange Drying Technique

Ultra-high molecular weight polyethylene(UHMWPE)membranes were prepared by 5 wt%UHMWPE/parafn oil gels via thermally induced phase separation method and dried in air without signifcant collapse.The UHMWPE membranes were annealed at 110℃ for increasing the pores size in order to decrease the capillary forces.Furthermore,a new multiple stage extractant exchange drying(MSEED)technique was adopted to decrease the shrinkage of the UHMWPE membranes.Specifcally,the parafn oil was extracted by dichloromethane,then dichloromethane was replaced by ethanol,next ethanol could be exchanged to other liquid which is non-afnity with UHMWPE,for example water.UHMWPE membranes(annealing for 25 min)dried by dichloromethane-ethanol-water-air process have the lowest volume shrinkage of 16.5%and the porosity is as high as 88.29%.Moreover,compared with supercritical CO_(2)(SC-CO_(2))drying,atmospheric drying UHMWPE membranes have a lower pure water permeance,but a higher carbon particles rejection.

Fat Re-Grafting in Facial Asymmetry: A 2-Case Report

Fat redistribution through recycling of previously grafted fat hasn’t been reported. Two facial asymmetry patients are presented with history of fat grafting to the mandibular angle areas. Collected fat from these formerly fat grafted zones and swollen on subsequent extra body weight gain has been re-grafted in the temporal regions for contour enhancement and has retained volume as photographically documented up to 30 months.