Protein Extraction and Enzymatic Hydrolysis of Ammonia-Treated Cassava Leaves (Manihot esculenta Crantz)

In the present work, cassava leaves were treated with 0.5 kg ammonia/kg dry matter at 78 °C and 30% moisture content in a 2-kg reactor. Protein extraction was carried out with a calcium hydroxide solution (pH 10) for 30 min at several temperatures (30 °C, 45 °C, 60 °C, 75 °C, and 90 °C) and solid/liquid ratios (1:10 and 1:15) in a thermostatized bath. Soluble protein content of the extracts was determined by Lowry’s method. Dry substrate concentrations of 5%, 7.5%, and 10% and enzyme doses of 2 and 5 IU/g dry matter were used for the enzymatic hydrolysis in an orbital incubator at 50 °C and 100 rpm. Both cellulase and xylanase were used. Reducing sugars produced were determined with the dinitrosalicylic acid method. The highest protein extraction yield for the ammonia-treated leaves was 29.10%, which was 50% higher than with the untreated leaves (20%), and was obtained at 90 °C with a 1:10 solid/liquid ratio. The concentrate had a protein content of 36.35% and the amino acid profile was suitable for swine and poultry. The highest sugar yield was 54.72% with respect to theoretical and was obtained with 5% solids and an enzyme dose of 5 IU/g dry matter. This yield was 3.4 times higher than the yield of the untreated leaves (16.13%). These results indicate that cassava leaves have a great potential for animal feeding and ethanol production. Both protein extraction and sugar yields may be enhanced by optimizing the ammonia treatment.     

Application of Physicochemical Treatment Allows Reutilization of <Emphasis Type="Italic">Arthrospira platensis</Emphasis> Exhausted Medium

Since cultivations of Arthrospira platensis have a high water demand, it is necessary to develop treatment methods for reusing the exhausted medium that may prevent environmental problems and obtaining useful biomass. The exhausted Schlösser medium obtained from A. platensis batch cultivation in bench-scale mini-tanks was treated by varying concentrations of different coagulants, ferric chloride (6, 10, and 14 mg L^?1) or ferric sulfate (15, 25, and 35 mg L^?1) and powdered activated carbon (PAC, 30 and 50 mg L^?1). Such treated effluent was restored with NaNO₃ and reused in new cultivations of A. platensis performed in Erlenmeyer flasks. Reusing media through the cultivation of A. platensis showed satisfactory results, particularly in the medium treated with ferric chloride and PAC. The maximum cell concentration obtained in the flasks was 1093 mg L^?1, which corresponded to the medium treated with ferric chloride (6 mg L^?1) and PAC (30 mg L^?1). This cellular growth was higher than in the medium treated with ferric sulfate and PAC, in which values of maximum cell concentration did not exceed 796 mg L^?1. The cultures in the media after treatment did not modify the biomass composition. Thus, combined coagulation/adsorption processes, commonly used in water treatment processes, can be efficient and viable for treating exhausted medium of A. platensis, allowing the production of such biomass with the reduction of production cost and saving water.     

Laser scribing on HOPG for graphene stamp printing on silicon wafer

Highly oriented pyrolytic graphite (HOPG) was scribed by pulsed laser beam to produce square patterns. Patterning of HOPG surface facilitates the detachment of graphene layers during contact printing. Direct HOPG-to-substrate and glue-assisted stamp printing of a few-layers graphene was compared. Printed graphene sheets were visualized by optical and scanning electron microscopy. The number of graphene layers was measured by atomic force microscopy. Glue-assisted stamp printing allows printing relatively large graphene sheets (40×40 μm) onto a silicon wafer. The presented method is easier to implement and is more flexible than the majority of existing ways of placing graphene sheets onto a substrate.     

Potential of Microalgae Carotenoids for Industrial Application

Applied Biochemistry and Biotechnology - Microalgae cultivation, when compared to the growth of higher plants, presents many advantages such as faster growth, higher biomass productivity, and...     

Turnaround in cyclic cosmology

It is speculated how dark energy in a brane world can help reconcile an infinitely cyclic cosmology with the second law of thermodynamics. A cyclic model is described, in which dark energy with w<-1 equation of state leads to a turnaround at a time, extremely shortly before the would-be big rip, at which both volume and entropy of our Universe decrease by a gigantic factor, while very many independent similarly small contracting universes are spawned. The entropy of our model decreases almost to zero at turnaround but increases for the remainder of the cycle by a vanishingly small amount during contraction, empty of matter, then by a large factor during inflationary expansion.     

Leaf protein from ammonia-treated dwarf elephant grass (Pennisetum purpureum) schum cv. mott)

Proteins can be an excellent by product of the biorefining of lignocellulosic materials. In this work, extraction conditions for the white leaf proteins (cytoplasmic) of ammonia-treated dwarf elephant grass were established to obtain a protein juice suitable for the production of leaf protein concentrates. A calcium hydroxide solution was used as extracting agent, at several solid-liquid ratios, pHs, temperatures, and times. Extractions were carried out in Erlenmeyer flasks containing 5 g (dry basis) of forage with constant agitation (100 rpm). The soluble protein content was determined by the Lowry method. Optimal extraction conditions for the ammonia-treated forage were 12.60 pH, 1:10 solid-liquid ratio, 90°C, and 30 min extraction time, resulting in 52.65% extraction yield. The ammonia treatment significantly increased (p<0.05) the release of proteins from the fibrous matrix, facilitating their extraction.