217 research outputs found
Protein haze formation in wines revisited. The stabilising effect of organic acids
The effect on the wine protein haze potential of five organic acids commonly encountered in wines (L(+)-
tartaric, L( )-malic, citric, succinic and gluconic acids) was assessed. All five acids, tested at 20 mM,
reduced dramatically the haze potential of proteins, either in wine or dissolved in water, throughout
the range of pH values typical of wines (i.e., from 2.8 through 3.8). Subtle differences among the acid
effects did not correlate with the number of their carboxyl groups, but were attributed to electrostatic
interactions that depend upon the acid pKa values, the protein pI values and the medium pH. These
results invalidate or question the validity of all experiments on wine proteins involving wine model solutions
containing organic acids. Overall, the results obtained in the present work clearly indicate that
organic acids with a common occurrence in wines exhibit a stabilising effect upon the haze potential
of the wine proteins
The Differentiation and Promotion of Studentsâ Rights in Portugal
This investigation includes a differential study (Study 1)
and a quasi-experimental research (Study 2). In Study 1, the objective
was to establish to what extent studentsâ rights existed and analyse
the differentiation between studentsâ rights with Portuguese and
immigrant mothers, throughout school years. The sample consisted of
537 students with Portuguese and immigrant mothers, distributed by
different school years (7th, 9th and 11th grades). The Childrenâs Rights
Scale (Hart et al., 1996; Veiga, 2001) was used. In Study 2, the purpose
was to analyse the effects on studentsâ rights of the use by teachers of a
communicational intervention program, supervised by school psychologists.
The sample involved 7th and 9th grade students, in a total of
four classes, two forming the experimental groups (n = 36) and two the
control groups (n = 43); as in Study 1, the Childrenâs Rights Scale was used. The results indicated the effectiveness of the communicational intervention program on studentsâ rights and are consistent with previous studies. An implication is that psychologists and teachers, working together and taking a human rights perspective, may develop an important role in projects to promote the studentsâ rights
Molecular assessment of cashew diversity unravels distinctive differentiation routes in CPLP countries
Comunicação OralN/
Decomposition and nutrient release of leguminous plants in coffee agroforestry systems.
Leguminous plants used as green manure are an important nutrient source for coffee plantations, especially for soils with low nutrient levels. Field experiments were conducted in the Zona da Mata of Minas Gerais State, Brazil to evaluate the decomposition and nutrient release rates of four leguminous species used as green manures (Arachis pintoi, Calopogonium mucunoides, Stizolobium aterrimum and
Stylosanthes guianensis) in a coffee agroforestry system under two different climate conditions. The initial N contents in plant residues varied from 25.7 to 37.0 g kg-1 and P from 2.4 to 3.0 g kg-1. The lignin/N, lignin/polyphenol and(lignin+polyphenol)/N ratios were low in all residues studied. Mass loss rates were highest in the first 15 days, when 25 % of the residues were decomposed. From 15 to 30 days, the decomposition rate decreased on both farms. On the farm in Pedra Dourada (PD), the decomposition constant k increased in the order C. mucunoides < S. aterrimum < S. guianensis < A. pintoi. On the farm in Araponga (ARA), there was no difference in the decomposition rate among leguminous plants. The N release rates varied from 0.0036 to 0.0096 d-1. Around 32 % of the total N content in the plant material was released in the first 15 days. In ARA, the N concentration in the S. aterrimum residues was always significantly higher than in the other residues. At the end of 360 days, the N released was 78 % in ARA and 89 % in PD of the initial content. Phosphorus was the most rapidly released nutrient (k values from 0.0165 to 0.0394 d-1). Residue decomposition and nutrient release did not correlate with initial residue chemistry and biochemistry, but differences in climatic conditions between the two study sites modified the decomposition rate constants
Passerini chemistries for synthesis of polymer pro-drug and polymersome drug delivery nanoparticles
New materials chemistries are urgently needed to overcome the limitations of existing biomedical materials in terms of preparation, functionality and versatility, and also in regards to their compatibility with biological environments. Here, we show that Passerini reactions are especially suited for the preparation of drug delivery materials, as with relatively few steps, polymers can be synthesized with functionality installed enabling drug conjugation and encapsulation, self-assembly into micellar or vesicular architectures, and with facile attachment triggerable chemistries. The polymers can be made with a variety of building blocks and assemble into nanoparticles, which are rapidly internalized in triple negative breast cancer (TNBC) cells. In addition, the polymers transport drug molecules efficiently through 3D cell cultures, and when designed with chemistries allowing pH-mediated release, exhibit greater efficacy against TNBC cells compared to the parent drug
- âŠ