Genome renewal: A new phenomenon revealed from a genetic study of 43 strains of Saccharomyces cerevisiae derived from natural fermentation of grape musts

We have analyzed by genetic means 43 strains of Saccharomyces that had been isolated from fermenting grape musts in Italy. Twenty eight of these strains were isolated from 28 cellars in the Region of Emilia Romagna. The other 15 strains came from 5 fermentations at four cellars near the city of Arpino, which is located south and east of Rome. We found that 20 of the 28 strains from Emilia Romagna were heterozygous at from one to seven loci. The balance were, within the limits of our detection, completely homozygous. All these strains appeared to be diploid and most were homozygous for the homothallism gene (HO/HO). Spore viability varied greatly between the different strains and showed an inverse relation with the degree of heterozygosity. Several of the strains, and in particular those from Arpino, yielded asci that came from genetically different cells. These different cells could be interpreted to have arisen from a heterozygote that had sporulated and, because of the HO gene, yielded homozygous diploid spore clones. We propose that natural wine yeast strains can undergo such changes and thereby change a multiple heterozygote into completely homozygous diploids, some of which may replace the original heterozygous diploid. We call this process ‘genome renewal’.     

Biotechnological H2S gas treatment with Thiobacillus ferrooxidans

In this paper a novel process for biotechnological abatement of hydrogen sulphide is presented which details the fundamentals of chemical and biological phenomena involved. The process is based on the combination of two steps to form a closed cycle which has special enviornmental advantages. The chemical step corresponds to the abatement reaction itself with absorption of the gas in a ferric solution. The biological step is related to the regeneration of the absorbing solution by means of specific bacterial strains. Particular interest is devoted to the biological kinetics of the regeneration stage, where several inhibition phenomena appear, and are also related to parameters such as temperature and pH. Results of experimental runs of gas absorption in a laboratory scale plant are also described.     

Experience over time: evaluating the experience of use of a squeezable interface in the medium term

The paper presents the user experience evaluation of Squeeze Me, an interactive cover for tablet and smartphone that enables continuous and expressive interaction with electronic devices. The cover has been used to implement ”Squeeze to zoom”, a mobile application to zoom in and out while taking a photograph from a tablet. The experience of use was evaluated in the short and medium term, comparing the Squeeze Me interaction modality with classic modalities for zooming in and out commonly available on tablets and smartphones. The evaluation process was conducted using AttrakDiff [3] a questionnaire that measures hedonic stimulation and identity, as well as pragmatic qualities and attractiveness of software products. Participants were asked to try out different interaction modalities for comparison in the short-term (67 people) and over 4 weeks (8 people). Results obtained in the short-term evaluation reveal that “Squeeze to zoom” was awarded higher values than the classic “Slide to zoom” in the hedonic quality-stimulation and attractiveness dimensions, whilst it obtained lower values in the pragmatic quality and hedonic quality-identity. However, the experience of use changed over time. During the longitudinal study, the usability of “Squeeze to zoom” improved whilst the attractiveness of “Slide to zoom” decreases significantly. Furthermore results reveal that “Squeeze to zoom” is significantly more appreciated for its hedonic qualities and the effect is maintained over time. This study highlights the importance of evaluating the experience of use over time, a practice that is almost ignored in the literature on Experience Design.     

Physical properties of 2-hydroxyethyl methacrylate-grafted silk fibers

This paper deals with the physical properties of silk fibers grafted with 2-hydroxyethyl methacrylate (HEMA). Both tensile strength and elongation measured in the dry and wet states gradually decreased with increasing weight gain. The initial modulus of the grafted silk fibers in the dry state sharply increased in the weight gain range of 0–16%, then decreased to a lower value than the reference untreated sample. The refractive indices parallel and perpendicular to the fiber axis decreased, though the former showed a steeper slope. Accordingly, birefringence and isotropic refractive index also decreased, suggesting a lower degree of crystallinity and molecular orientation of grafted silk fibers. DSC, TMA, and TGA curves of the HEMA-grafted silk fibers indicated an increased higher thermal stability of silk fibers due to the HEMA grafting. The dynamic mechanical measurements showed that the thermally induced molecular movement of both amorphous and crystalline domains of silk fibers was enhanced by HEMA grafting. X-ray diffraction curves, however, implied that the crystalline structure of the silk fibroin remained unchanged regardless of HEMA polymerization. The introduction of HEMA polymer in silk fibers was evidenced by the infrared spectra, exhibiting the absorption bands characteristic of either the grafted HEMA polymer and the fibroin molecules with ordered β structure. © 1993 John Wiley & Sons, Inc.     

Low-Temperature Synthesis and Properties of LaMnO3±d and La0.67R0.33MnO3±d (R = Ca, Sr, Ba) from Citrate Precursors

LaMn_{1− y} ³⁺Mn _y ⁴⁺O_3±d and La_0.67R_0.33Mn_{1− y} ³⁺Mn _y ⁴⁺O_3±d (R = Ca, Sr, Ba) phases were synthesized at 350°C by using very reactive, amorphous precursors obtained from the stoichiometric citrate solutions. The chemical process was optimized with respect to the solution concentration, pH, and additives. The precursor reactions were investigated as a function of the cation stoichiometry and the additive by simultaneous thermal and thermogravimetric analysis and X-ray diffraction. The reaction pathway was found to be independent of the cation stoichiometry, but related to the acid or base additive. The annealing temperature was systematically increased in the 350–1200°C interval and the La_0.67Sr_0.33MnO_3±d properties (i.e., crystal sizes, Mn average valence, Curie temperature, magnetization, magnetic susceptibility) were measured and found to vary consistently as a function of it.     

X-ray microscopy of plant cells by using LiF crystal as a detector

A lithium fluoride (LiF) crystal has been utilized as a new soft X-ray detector to image different biological samples at a high spatial resolution. This new type of image detector for X-ray microscopy has many interesting properties: high resolution (nanometer scale), permanent storage of images, the ability to clear the image and reuse the LiF crystal, and high contrast with greater dynamic range. Cells of the unicellular green algae Chlamydomonas dysosmos and Chlorella sorokiniana, and pollen grains of Olea europea have been used as biological materials for imaging. The biological samples were imaged on LiF crystals by using the soft X-ray contact microscopy and contact micro-radiography techniques. The laser plasma soft X-ray source was generated using a Nd:YAG/Glass laser focused on a solid target. The X-ray energy range for image acquisition was in the water-window spectral range for single shot contact microscopy of very thin biological samples (single cells) and around 1 keV for multishots microradiography. The main aim of this article is to highlight the possibility of using a LiF crystal as a detector for the biological imaging using soft X-ray radiation and to demonstrate its ability to visualize the microstructure within living cells.     

Cultural Landscape: Stone Towers on Mount Etna

This work reports the findings of an investigation by Etna’s local councils whose publicly owned land has high concentrations of particularly significant towers. The towers are original stone constructions, presumed to have been built between the end of the 1700s and the beginning of the 1900s and so are unrelated to medieval towers, emblems of ancient yet sophisticated building techniques and located in numerous agricultural areas on the slopes of Mount Etna, Europe’s most active volcano. They are built out of the stones removed from the agricultural land of the soils regenerated from the lava flows wedged in between basalt outcrops. Together with other stone artefacts, they form part of a renewable heritage of great value both for their recognised role in maintaining biodiversity as well as for their cultural, landscape and historical significance. These constructions are in a state of extreme abandonment or are gradually disappearing due to the loss of agriculture or the changeover of agricultural land into building sites. The enquiry used historical documents, censuses of tower characteristics and field data. Four council zones were identified and in each only clearly identifiable towers were considered (total: 19). The field data highlighted considerable architectural complexity in their proportions and construction techniques. Their historico-cultural-landscape validity was confirmed as was the necessity of appropriate and urgent state intervention.