Search results for "acids"

Conservation of optical purity of amino acids: a principal problem in biochemical and proto-biochemical systems.

1981

Dor L-amino acids, regardless of their state (peptide-bound or free, in the solid state or in aqueous solution), tend to racemize. In a living cell this racemization is usually compensated by specific degradation and replacement of the unwanted polypeptides that contain the wrong enantiomers. But a few long-lived proteins that are synthesized at or near birth are never replaced. Well investigated is the racemization of L-aspartic acid at a rate of 0.1 to 1.14 per cent per year in proteins from lenses and dentine. Increased racemization of eye lens proteins has been related to a form of human eye disease known as brunescent cataracts. Also quite well investigated is the racemization of amino…

Optimum design and operation of primary sludge fermentation schemes for volatile fatty acids production.

2003

This paper presents a model-knowledge based algorithm for optimising the primary sludge fermentation process design and operation. This is a recently used method to obtain the volatile fatty acids (VFA), needed to improve biological nutrient removal processes, directly from the raw wastewater. The proposed algorithm consists in a heuristic reasoning algorithm based on the expert knowledge of the process. Only effluent VFA and the sludge blanket height (SBH) have to be set as design criteria, and the optimisation algorithm obtains the minimum return sludge and waste sludge flow rates which fulfil those design criteria. A pilot plant fed with municipal raw wastewater was operated in order to …

Cuticular hydrocarbon profiles in Blattella germanica: effects of halofenozide, boric acid and benfuracarb

2006

1379-1176 (Print) Journal Article; In order to complete previous studies conducted on Blattella germanica, three insecticides from different groups were evaluated: boric acid, an inorganic compound, benfuracarb, a carbamate, and halofenozide, a non-steroidal ecdysone agonist. Boric acid (8.20%, LD50) and benfuracarb (2%, LD50) were incorporated into the diet and orally administrated to newly emerged adults of both sexes, while halofenozide (0.33%, LD50) was applied topically. Hydrocarbons extracts was made on bidistilled pentane from control and treated series sampled 6 days following treatment. Extracts was analyzed by gas chromatography. Data showed that cuticular profiles of control and …

Faces, facets, and functions of biomolecular condensates driven by multivalent proteins and nucleic acids

2021

Fast and Efficient Microwave-Assisted Synthesis of Perylenebisimides

2015

Perylene-3,4,9,10-tetracarboxylic acid bisimides have been widely studied as industrial pigments. Lately, these dyes have drawn considerable attention because of applications as photocatalysts and organic semi-conductors. Here, we report a novel method for fast and efficient synthesis of many different perylenebisimides, based on microwave-assisted reactions.

Influencia del procesado industrial sobre las características químico-físicas y contenido en lípidos y antioxidantes del salvado de arroz

2009

Se investigaron las características químico-físicas de los salvados de arroz en distintos momentos de su procesado industrial, incluyendo materia prima (salvados de arroz blanco y vaporizado), salvado peletizado y salvado desgrasado. Se determinó la humedad, la acidez y el índice de peróxidos. Utilizando extractos en éter de petróleo y cromatografía de gases, se estableció el contenido lipídico total y los perfiles de los ácidos grasos. Mediante HPLC se determinaron los tocoferoles y el γ-orizanol. El salvado de arroz vaporizado mostró la mayor concentración de lípidos y la menor acidez, lo que indica que el vaporizado es el proceso más eficaz para estabilizar el salvado. Los ácidos oleico,…

Amino acids requirements of measles virus in HeLa cells.

1973

A low plating efficiency for measles virus was obtained when arginine, threonine and isoleucine were omitted from Eagle's basal medium and a stimulatory effect on the plaque production was produced by increasing the concentration up to 0.5 mm of arginine and glutamine. However, of all amino acids in Eagle's basal medium, only methionine was found to be essential for the synthesis of infectious progeny virus. Omission of any one of the other amino acids from the culture medium permitted limited virus production, but none whatever could be detected in the absence of mediummethionine. Moreover, when methionine was restored to infected cultures after 24 hours of deprivation, release of virus be…

Mechanical properties of provisional dental materials: A systematic review and meta-analysis

2018

Provisional restorations represent an important phase during the rehabilitation process, knowledge of the mechanical properties of the available materials allows us to predict their clinical performance. At present, there is no systematic review, which supports the clinicians' criteria, in the selection of a specific material over another for a particular clinical situation. The purpose of this systematic review and meta-analysis was to assess and compare the mechanical properties of dimethacrylates and monomethacrylates used in fabricating direct provisional restorations, in terms of flexural strength, fracture toughness and hardness. This review followed the PRISMA guidelines. The searche…

A comparison of the effects of ?-ketotriazole, MCPA and carbaryl on the plasma membrane Mg2+-ATPase activity and lipid composition of rice shoots (Or…

1993

The effect of γ-ketotriazole, MCPA and carbaryl on the lipid composition and ATPase activity associated with plasma membrane fractions from rice (Oryza sativa cv Bahia) shoots was investigated. With γ-ketotriazole and MCPA treatments the relative amount of δ5-avenasterol (%) was reduced in the plasma membrane, whereas with γ-ketotriazole a reduction was also found in the sitosterol content, expressed as a percentage of the total free sterol composition. The fatty acyl chain length of phosphatidylcholine fractions from MCPA-treated plants was also reduced. The plasma membrane Mg2+-ATPase activity was only stimulated in MCPA-treated plants. No changes were observed in lipid composition or ATP…

Experimental investigation and modeling of diffusion dialysis for HCl recovery from waste pickling solution

2019

Abstract Hydrochloric acid recovery from pickling solutions was studied by employing a batch diffusion dialysis (DD) laboratory test-rig equipped with Fumasep membranes. The effect of main operating parameters such as HCl concentration (0.1–3 M) and the presence of Fe2+ (up to 150 g/l) was investigated to simulate the system operation with real industrial streams. The variation of HCl, Fe2+ and water flux was identified. When only HCl is present, a recovery efficiency of 100% was reached. In the presence of FeCl2, higher acid recovery efficiencies, up to 150%, were observed due to the so-called “salt effect”, which promotes the passage of acid even against its concentration gradient. A 7% l…