Search results for " chemical engineering"

In vitro antileishmanial activity of aza-scorpiand macrocycles. Inhibition of the antioxidant enzyme iron superoxide dismutase

2016

The in vitro leishmanicidal activity of a series of nine aza-scorpiand-like macrocycles, recently synthesized, was tested on Leishmania infantum, Leishmania braziliensis and Leishmania donovani parasites, using promastigotes and intracellular amastigotes forms. The cytotoxicity of the tested compounds on J774.2 macrophage cells was also measured. Four of the tested compounds (1, 2, 8 and 9) showed selectivity indexes higher than those of the reference drug Glucantime for the three Leishmania species. Moreover, the data on infection rates and on amastigotes showed that compounds 1, 2, 8 and 9 are the most active against the three Leishmania species. The changes in the excretion product profi…

Molecular Mechanism of ATP Hydrolysis in an ABC Transporter

2018

Hydrolysis of nucleoside triphosphate (NTP) plays a key role for the function of many biomolecular systems. However, the chemistry of the catalytic reaction in terms of an atomic-level understanding of the structural, dynamic, and free energy changes associated with it often remains unknown. Here, we report the molecular mechanism of adenosine triphosphate (ATP) hydrolysis in the ATP-binding cassette (ABC) transporter BtuCD-F. Free energy profiles obtained from hybrid quantum mechanical/molecular mechanical (QM/MM) molecular dynamics (MD) simulations show that the hydrolysis reaction proceeds in a stepwise manner. First, nucleophilic attack of an activated lytic water molecule at the ATP γ-…

Review: the Use of Electromyography on Food Texture Assessment

2001

Sensory evaluation (SE) involves evoking, measuring and interpreting human responses to the properties of foods. Among these properties texture is an important one for food acceptability. Texture is mainly perceived through mastication, a process that changes food characteristics throughout time by comminuting and salivation. Electromyography (EMG) has emerged as a new tool in sensory evaluation mainly for assessing texture characteristics. Thus, it is interesting to analyze the knowledge so far generated and the procedures employed. Bipolar surface electrodes are placed on the four main masticatory muscles (masseter right-left and temporalis right-left) and their electric activity recorded…

Introducing Clicker Training as a Cognitive Enrichment for Laboratory Mice

2017

Establishing new refinement strategies in laboratory animal science is a central goal in fulfilling the requirements of Directive 2010/63/EU. Previous research determined a profound impact of gentle handling protocols on the well-being of laboratory mice. By introducing clicker training to the keeping of mice, not only do we promote the amicable treatment of mice, but we also enable them to experience cognitive enrichment. Clicker training is a form of positive reinforcement training using a conditioned secondary reinforcer, the "click" sound of a clicker, which serves as a time bridge between the strengthened behavior and an upcoming reward. The effective implementation of the clicker trai…

ODELAY: A Large-scale Method for Multi-parameter Quantification of Yeast Growth

2017

Growth phenotypes of microorganisms are a strong indicator of their underlying genetic fitness and can be segregated into 3 growth regimes: lag-phase, log-phase, and stationary-phase. Each growth phase can reveal different aspects of fitness that are related to various environmental and genetic conditions. High-resolution and quantitative measurements of all 3 phases of growth are generally difficult to obtain. Here we present a detailed method to characterize all 3 growth phases on solid media using an assay called One-cell Doubling Evaluation of Living Arrays of Yeast (ODELAY). ODELAY quantifies growth phenotypes of individual cells growing into colonies on solid media using time-lapse mi…

New strategies for the development of innovative fermented meat products: a review regarding the incorporation of probiotics and dietary fibers

2019

Over the last decades, consumer´s preference for and their attention to food products presented as healthy and with favorable nutritional information has been significantly increased. In this line,...

Opuntia Ficus Indica Edible Parts: A Food and Nutritional Security Perspective

2020

Cactus Opuntia ficus indica is widely distributed in (semi-) arid regions. Fruit and cladodes are processed into many food products. Cladodes are used as vegetables, but their main use is flour, wh...

2019

Structural DNA nanotechnology provides a viable route for building from the bottom-up using DNA as construction material. The most common DNA nanofabrication technique is called DNA origami, and it allows high-throughput synthesis of accurate and highly versatile structures with nanometer-level precision. Here, it is shown how the spatial information of DNA origami can be transferred to metallic nanostructures by combining the bottom-up DNA origami with the conventionally used top-down lithography approaches. This allows fabrication of billions of tiny nanostructures in one step onto selected substrates. The method is demonstrated using bowtie DNA origami to create metallic bowtie-shaped an…

Alginate/silica composite hydrogel as a potential morphogenetically active scaffold for three-dimensional tissue engineering

2013

Pursuing our aim to develop a biomimetic synthetic scaffold suitable for tissue engineering, we embedded bone cells, osteoblast-related SaOS-2 cells and osteoclast-like RAW 264.7 cells, into beads, formed of a Na-alginate-based or a silica-containing Na-alginate-based hydrogel matrix. The beads were incubated either separately (only one cell line in a culture dish) or co-incubated (SaOS-2-containing beads and RAW 264.7 beads). The alginate and alginate/silica hydrogel matrices were found not to impair the viability of the encapsulated cells. In these matrices the SaOS-2 cells retain their capacity to synthesize hydroxyapatite crystallites. The mechanical properties, including surface roughn…

Interactions between volatiles and lipids in complex systems

1998

Partition equilibria of three aroma compounds in three different biphasic systems were studied by a liquid/liquid partition technique to investigate interactions that occur between volatiles and lipids in biphasic solutions. The lipids used were linoleic acid and ricinoleic acid and tetradecane as a model. The three aroma compounds were ethyl acetate, 2,5-dimethylpyrazine, and oct-1-en-3-ol. The results showed that the intermolecular forces involved were weak. Infrared spectroscopy was then performed on binary systems (tetradecane and linoleic acid or aroma compound) and on ternary systems (tetradecane, linoleic acid, and aroma compound) to determine the nature of the interactions. This met…