Academic literature on the topic 'Atmospheric lyophilization'

During the Pre-Colombian period magueys were used in Mesoamerica for their sap, which is named “aguamiel” (literally “honey water” in Spanish). Aguamiel is then fermented into “pulque”, followed by (in order of importance): textiles, apparel, different thicknesses cords, food (sweetener, syrup, vinegar, flower buds, and cooked immature flowering stalks), firewood and construction materials. The maguey syrup is a product that is traditionally obtained by concentrating the aguamiel by means of an artisanal evaporation treatment (high temperatures, atmospheric pressure and prolonged times). The nutritional and nutraceutical value of this concentrate is unknown despite its wide consumption since pre-Hispanic times in various regions of Mexico. The objective of this work was to evaluate the nutritional value and the content of antioxidant compounds of the maguey syrup obtained from the aguamiel (Agave salmiana and A. mapisaga) through three elaboration treatments (artisanal evaporation, evaporation under reduced pressure and lyophilization). The best species for the production of maguey syrup turned out to be the aguamiel of the A. salmiana due to its nutritional and nutraceutical attributes, higher content of reducing sugars and lower sucrose compared to that of A. mapisaga. The maguey syrup is a sweetener with a higher content of protein (3320 mg 100-1) in comparison to bee honey (152.7 mg 100 g-1). The maguey syrup obtained by lyophilization (LYT) retained the nutraceutical value; but its antioxidant activity was statistically equal to the syrup obtained by evaporation under reduced pressure (RPT), and the artisanal evaporation treatment (AET) had a decrease in vitamin C content in comparison to LYT and RPT. The syrups obtained by RPT and AET presented different degrees of non-enzymatic darkening, possibly due to the formation of melanoidins (dark pigments). The darkest syrup obtained by AET had the highest antioxidant capacity (987.24 μM TE 100 g-1) associated to a higher content of phenolic compounds (593.74 mg GAE 100 g-1).

The question of the stability of lyophilized culture, namely - the maximum preservation of its viability – is an extremely important indicator of microbiological work. Of particular interest is the study of the impact on the preservation of the viability of the lyophilized culture of the gas composition of the ampoule filler after the actual lyophilization. In this regard, an analysis was performed and the viability of hemolytic pasteurella cells was evaluated, the ampoules of which were filled with nitrogen, argon, respectively, or simply sealed in a vacuum atmosphere. The experiment used materials that reflect the content of live pasteurella in ampoule lyophilized samples when stored for 12 months from the date of determination of the initial concentration. The study of the properties of lyophilically dried samples of hemolytic pasteurel in an atmosphere of various chemical and physical state after 12 months of storage at 4-10 °C was as follows. Loss of living cells in specimens enclosed in ampoules under an atmosphere of nitrogen was 24.5%, argon - 43.7%, and in sealed vials with vacuum - 14.7 %. The choice of temperature range 20-22 °C, in addition to the previously mentioned regime of 4-10 °C, was influenced by the need to verify its effect on the viability of lyophilized strains of hemolytic pasteurellosis. This is explained by the fact that most work with culture is most often carried out under this regime. Temperatures of 20-22 °C or close to it can be decisive in case of failure of refrigeration equipment or in case of other risks. At a storage temperature of 20-22 °C, these indicators were 76.8 %, respectively, 80.6 % and 67.5 %. The average survival rates of pasteurella make it possible to detect a probable difference (p <0,05) between their number in ampoules with an atmosphere of inert gases compared with vials sealed under vacuum. The obtained data suggest that the viability of bacteria in ampoules with nitrogen atmosphere has a level that meets the international requirements for working with biological bacterial agents. The obtained data suggest that the viability of bacteria in ampoules with nitrogen atmosphere has a level that meets the international requirements for working with biological bacterial agents.

Abstract Background: Neonicotinoids are among the most widely used insecticides. Recently, there has been concern associated with unintended adverse effects on honeybees and aquatic invertebrates at low parts-per-trillion levels. Objective: There is a need for LC-MS/MS methods that are capable of high-throughput measurements of the most widely used neonicotinoids at environmentally relevant concentrations in surface water. Methods: This method allows for quantitation of acetamiprid, clothianidin, imidacloprid, dinotefuran, nitenpyram, thiacloprid, and thiamethoxam in surface water. Deuterated internal standards are added to 20 mL environmental samples, which are concentrated by lyophilisation and reconstituted with methanol followed by acetonitrile. Results: A large variation of mean recovery efficiencies across five different surface water sampling sites within this study was observed, ranging from 45 to 74%. This demonstrated the need for labelled internal standards to compensate for these differences. Atmospheric pressure chemical ionization (APCI) performed better than electrospray ionization (ESI) with limited matrix suppression, achieving 71–110% of the laboratory fortified blank signal. Neonicotinoids were resolved on a C18 column using a 5 min LC method, in which MQL ranged between 0.93 and 4.88 ng/L. Conclusions: This method enables cost effective, accurate, and reproducible monitoring of these pesticides in the aquatic environment. Highlights: Lyophilization is used for high throughput concentration of neonicotinoids in surface water. Variations in matrix effects between samples was greatly reduced by using APCI compared with ESI. Clothianidin and thiamethoxam were detected in all samples with levels ranging from below method quantitation limit to 65 ng/L.

Research and development on artificial photosynthesis provide a new direction to obtain sustainable energy. To increase the artificial photosynthesis reaction rates and the efficiency of collecting the energy product, a novel artificial photosynthesis device was designed and developed to constrain the photosynthesis reactions in chitosan porous structure. Both 3D printing and molding-casting could be used in fabrication of chitosan structure on artificial photosynthesis devices. In molding and casting, the molds were made by acrylonitrile butadiene styrene (ABS) and polydimethylsiloxane (PDMS). Concurrently, 3D interconnected chitosan channels were built with a user-made heterogeneous 3D rapid prototyping machine, and the lyophilization method was used to generate the micro or nano pores inside the chitosan scaffold. After lyophilization, the pore size and porosity was generated by MATLAB image processing. CO2 absorption was simulated based on porous structures properties when import the chitosan into the artificial photosynthesis devices. The results suggested that chitosan porous structure is a good candidate to be an interface between atmosphere and micro-fluidic devices with biochemical reactions.