Variability of intact rock mechanical properties for some metamorphic rock types and its implications on the number of test specimens

Intact rock strength and stiffness properties are commonly used in rock mass mechanical characterization, and their evaluation is usually based on laboratory tests. Due to the variability that affects strength and stiffness parameters, the determination of the number of laboratory-tested specimens required to obtain a reliable reference value is very useful. However, many studies reported in apposite literature focused only on the variability of strength parameters. This study investigates the variability of some of the most important strength and stiffness properties (unconfined compressive strength, indirect tensile strength, tangent and secant Young’s moduli, Poisson’s ratio) by applying statistical methods (statistical decision theory and statistical inference theory). A data set of 451 laboratory tests was used, performed on three rock types. The statistical analyses were applied with the aim of assessing how closely intact rock laboratory data follow a normal distribution and determining the minimum number of specimens required to obtain a reliable average value of the parameters in relation to a targeted precision index for a confidence level of 95 %. The results indicate that the minimum number of samples needed varies depending on rock and test types. Among the stiffness properties, tangent Young’s modulus has a lower variability than both the secant modulus and the Poisson’s ratio, whereas in terms of strength parameters, unconfined compressive strength is subject to greater variability than indirect tensile strength.     

The Importance of Digging into the Genetics of SMN Genes in the Therapeutic Scenario of Spinal Muscular Atrophy

After 26 years of discovery of the determinant survival motor neuron 1 and the modifier survival motor neuron 2 genes (SMN1 and SMN2, respectively), three SMN-dependent specific therapies are already approved by FDA and EMA and, as a consequence, worldwide SMA patients are currently under clinical investigation and treatment. Bi-allelic pathogenic variants (mostly deletions) in SMN1 should be detected in SMA patients to confirm the disease. Determination of SMN2 copy number has been historically employed to correlate with the phenotype, predict disease evolution, stratify patients for clinical trials and to define those eligible for treatment. In view that discordant genotype-phenotype correlations are present in SMA, besides technical issues with detection of SMN2 copy number, we have hypothesized that copy number determination is only the tip of the iceberg and that more deepen studies of variants, sequencing and structures of the SMN2 genes are necessary for a better understanding of the disease as well as to investigate possible influences in treatment responses. Here, we highlight the importance of a comprehensive approach of SMN1 and SMN2 genetics with the perspective to apply for better prediction of SMA in positive neonatal screening cases and early diagnosis to start treatments.     

Influence of space allowance and housing conditions on the welfare, immune response and production performance of dairy ewes

The experiment used 45 Comisana ewes, divided into 3 groups of 15. The aim was to determine the effects of two different stocking densities and two different housing conditions on welfare, and on production performance of dairy ewes. The stocking densities tested were: high stocking density (1 x 5 m2/ewe, HD group) and low stocking density (3 m2/ewe, LD group); the two housing conditions tested were: ewes housed indoors (LD group, 3 m2/ewe) and ewes allowed to use an outdoor area (LDP group, 3 m2/ewe divided into 1 x 5 m2/ewe indoors and 1 x 5 m2/ewe outdoors). At the beginning of the experiment, and then every 2 months, the cell-mediated immune status of sheep was evaluated. One month after the beginning of the experiment, and 20 d later, the ewes were injected with chicken egg albumin (OVA) to assess their humoural immune responses. Starting from the beginning of the experiment and then monthly, behavioural activities of ewes were monitored using 15-min scans. After lamb weaning, milk yield from individual ewes was measured and milk composition analysed weekly. Housing conditions (low density reared ewes indoors v. low density reared ewes with free access to an outdoor area) affected cell-mediated response, which was higher in LDP than in LD ewes. Concentrations of anti-OVA IgG were mainly influenced by space allowance, with higher antibody titres in LD than in HD ewes throughout the experiment. Both housing conditions and space allowance affected sheep behavioural activities: a greater proportion of LDP ewes displayed standing and drinking behaviours than LD ewes, and a greater proportion of LD ewes was observed walking than HD ewes. Ewes allowed access to the outdoor area had a higher protein content and lower somatic cell count in their milk, whereas reduced space allowance led to a reduction in milk yield and an increase in somatic cell count of milk. Results indicate that both increased space allowance and availability of outdoor area can improve the welfare and production performance of the lactating ewe.     

The Effect of Colour Contrast on Consumers' Attentive Behaviours and Perception of Fresh Produce

The market for fruits and vegetables has received considerable interest in recent years, with much of its growth attributed to consumer interest in nutrition and health. Quality has been indicated to be the most important factor in produce sales, and appearance is of noted significance with regard to perceived quality. The broad objectives of this research were to identify the impact of simultaneous colour contrast (i.e. the produce viewed through a mesh bag) on (a) attentive behaviours as measured by eye tracking and (b) perceived quality, visual appeal and purchase intention as measured with a Likert scale. To accomplish these objectives, six different types of produce (red apples, oranges, lemons, green apples, purple onions and white onions) were photographed with four differently coloured mesh treatments: the same (as the produce), complementary, complementary‐analogous and analogous. Visual stimuli were then presented during the eye tracking study and in a subsequent questionnaire. Colour contrast was found to have a significant effect on both resultant eye tracking variables [number of visual fixations (p < 0.001) and time spent (p < 0.001)]. Produce shown with mesh of the same, or an analogous colour, induced significantly more visual fixations and more time than those depicted with complementary or complementary‐analogous treatments. Subsequent to the eye tracking study, subjects were shown the stimuli and asked to rate the expected quality, visual appeal and their purchase intention for the 24 photographs (6 types of produce × 4 colour contrasts) by using a Likert scale. Pairwise comparisons suggested that produce packaged in the same or analogous mesh were perceived by subjects to be of higher quality, more visually appealing and evoked a higher level of purchase intention than those packaged in complementary or complementary‐analogous mesh (α = 0.05). Copyright © 2012 John Wiley & Sons, Ltd.     

The surface modification of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) copolymers to improve the attachment of urothelial cells

Biocompatible and biodegradable poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) [P(HB-co-HHx)] substrates were modified to improve the attachment of porcine urothelial cell culture. The pristine copolymer exhibits excellent mechanical properties to replace the bladder tissue, but its surface lacks chemical functionalities to interact with cells. Thus, wet chemical treatments based on NaOH and ethylenediamine in aqueous [ED(aq)] and isopropanol [ED(isoOH)] media to functionalize the P(HB-co-HHx) films surfaces were compared. Among these treatments, short ED(aq) treatment was able to decrease the hydrophobicity, rendering a surface with amino groups and without a significant alteration of the mechanical properties. Furthermore, to enhance the interaction with urothelial cells, laminin derived YIGSR sequence was covalently bound to these amino functionalized substrates. The focal attachment was clearly improved with this last treatment, comparing with those results found with the unmodified and first-step functionalized P(HB-co-HHx).     

Novel silica/bis(3-aminopropyl) polyethylene glycol inorganic/organic hybrids by sol–gel chemistry

Biomaterials are needed for tissue regeneration applications that provide control of mechanical properties and enhanced toughness compared to conventional bioceramics. New sol–gel hybrids were developed with interpenetrating networks of silica and bis(3-aminopropyl) polyethylene glycol. Covalent coupling between the organic and the inorganic components was used to control mechanical properties of the hybrids. The objective was to synthesise and characterise a bis(3-aminopropyl) polyethylene glycol silica hybrid material with 35 wt% organic and 65 wt% inorganic and covalent coupling between the components. A coupling agent, 3-glycidopropyltrimethoxysilane (GPTMS) was used to form the covalent links. The hypothesis was that the epoxy ring of the GPTMS would react with the polymer, leaving a polymer functionalised with siloxane groups. In a sol of hydrolysed tetraethyl orthosilicate (TEOS) the siloxanes from the GPTMS form –Si–O–Si– bonds between the functionalised polymer and the silica network. Bis(3-aminopropyl) polyethylene glycol contains two terminal amino groups available for the covalent functionalisation with the epoxy group of GPTMS. Hybrids with 35 wt% organic and 65 wt% inorganic with a ratio of GPTMS:PEG of 1:4 were proven to have an excellent balance between strain to failure (10%) and compressive strength (20 MPa). However, the functionalisation of the polymer was followed by liquid NMR as a function of the aging time and temperature and the expected reaction of nucleophilic attack of the epoxy ring by the amino group of the polymer did not happen until the water was removed from the system during drying. Increasing the amount of GPTMS decreased rate of weight loss during immersion in TRIS buffer solution.     

Taking a learning approach to community-based strategic environmental assessment: results from a Costa Rican case study

This paper describes an innovative approach to environmental assessment that built local capacity enabling a more sustainable management of natural resources. It presents learning outcomes from a community-based strategic environmental assessment (CBSEA) involving communities from two Costa Rican watersheds who assessed the Instituto Costarricense de Electricidad's (ICE) proposed agro-conservation programme. Participants were engaged throughout the CBSEA process, from planning to the implementation of four highly interactive workshops representing steps in a strategic environmental assessment. Instrumental learning results included: learning about CBSEA and its role in programme planning; developing problem-solving skills related to assessing impacts and creating mitigation strategies; effective group-working strategies; and technical information. Communicative learning outcomes included becoming more self-aware, and appreciating environmental conservation and collaboration. ICE learnt a participatory methodology and reconsidered communities' role in programme planning. Findings contribute to understanding the process of adult learning in cross-cultural contexts and the link between individual learning and social action.     

Microstructure and Nanoindentation Properties of Surface Textures Obtained by Laser Machining and Molding in Silicon Carbide

A surface texture consisting of an array of holes in SiC components was obtained by either conventional molding in the green state or post sintering laser machining. According to microstructural analysis, very regular holes were obtained by laser machining with minimal microstructural damage. Irregular holes with defects and voids were instead found for the surface textures obtained via molding. Nanoindentation tests were performed in the areas close to the holes and no significant alteration of the mechanical properties was found after laser machining.