Ecology of aspergillosis: insights into the pathogenic potency of Aspergillus fumigatus and some other Aspergillus species

Fungi of the genus Aspergillus are widespread in the environment. Some Aspergillus species, most commonly Aspergillus fumigatus, may lead to a variety of allergic reactions and life-threatening systemic infections in humans. Invasive aspergillosis occurs primarily in patients with severe immunodeficiency, and has dramatically increased in recent years. There are several factors at play that contribute to aspergillosis, including both fungus and host-related factors such as strain virulence and host pulmonary structure/immune status, respectively. The environmental tenacity of Aspergilllus, its dominance in diverse microbial communities/habitats, and its ability to navigate the ecophysiological and biophysical challenges of host infection are attributable, in large part, to a robust stress-tolerance biology and exceptional capacity to generate cell-available energy. Aspects of its stress metabolism, ecology, interactions with diverse animal hosts, clinical presentations and treatment regimens have been well-studied over the past years. Here, we synthesize these findings in relation to the way in which some Aspergillus species have become successful opportunistic pathogens of human- and other animal hosts. We focus on the biophysical capabilities of Aspergillus pathogens, key aspects of their ecophysiology and the flexibility to undergo a sexual cycle or form cryptic species. Additionally, recent advances in diagnosis of the disease are discussed as well as implications in relation to questions that have yet to be resolved.

Brock University Coat of Arms

The armorial bearings for Brock University, or more simply the University Coat of Arms, or crest, was designed in a large part by Presdent Gibson, assisted by other members of the Board of Governors (A preliminary design can be seen here). The Coat of Arms was granted to Brock University on March 17th, 1965. The Coat of Arms consist of an eagle, taken from General Brock’s own arms, displayed against a scarlet background - one of the official colours of Brock University. Immediately above it on a chief argent is displayed a maple-leaf (for Canada), a scallop shell (from the Lincoln and Welland regiment), and a trillium (for the province of Ontario). An open book fronts the eagle representing learning and knowledge. The crest itself is made up of a torch symbolizing learning, surrounded by a serpent for wisdom, with two calumet or North American pipes of peace, to symbolize Canada, friendship and agreement. The supporters consist of a beaver on the dexter side, emblematic of Canada and representing work and industry in learning. On the sinister side, a brock or badger (also in commemoration of General Brock) represents tenacity of purpose. The motto 'Surgite' is visible just below the arms.

Explaining voice behaviour: The roles of personal resources, social interdependence, and supervisor leadership style

This study contributes to current research on voice behaviour by investigating several under-explored drivers that motivate employees’ expression of constructive ideas about work-related issues. It draws from the concept of psychological climate to examine how voice behaviour is influenced by employees’ (1) personal resources (tenacity and passion for work), (2) perceptions of social interdependence (task and outcome interdependence), and (3) supervisor leadership style (transformational and transactional). Using a multi-source research design, surveys were administered to 226 employees and to 24 supervisors at a Canadian-based not-for-profit organization. The hypotheses are tested with hierarchical regression analysis. The results indicate that employees are more likely to engage in voice behaviour to the extent that they exhibit higher levels of passion for work. Further, their voice behaviour is lower to the extent that their supervisor adopts a transformational leadership style characterized by high performance expectations or a transactional leadership style based on contingent rewards and contingent punishment behaviours. The study reveals that there are no significant effects of tenacity, social interdependence, and behaviour-focused transformational leadership on voice. The findings have significant implications for organizations that seek to encourage employee behaviours that help improve current work practices or undo harmful situations.

Vida y muerte empresarial. Estudios empíricos de perdurabilidad - de la morbilidad a la perdurabilidad, estudios empresas galardonadas Premio Ave Fenix

Con esta investigación se pretende hacer una aproximación a la identificación de los pasos que utilizaron las empresas para salir de la crisis empresarial que presentaban, analizando los posibles errores que hayan afectado significativamente a la empresa, en los ámbitos económicos, sociales y morales, esto con el fin de corregirlos y aprender de ellos logrando perdurar en el mercado laboral empresarial. A estas empresas que han pasado por estos procesos de mejoras continuas son nominadas al premio Ave Fénix como empresas de resurgimiento empresarial, este galardón reconoce el esfuerzo de las empresas que logran resurgir como el Ave Fénix, al superar las dificultades que las condujeron al acuerdo de restructuración empresarial que contempla la Ley 550/1999. Con este galardón, la Universidad del Rosario en cooperación con la Superintendencia de Sociedades reconocen a las empresas que, en medio de una crisis, abocadas a un proceso de liquidación voluntaria u obligatoria, han demostrado tenacidad al resurgir - de la mano de Supersociedades - o las que se reestructuran y se establecen así como ejemplos de perdurabilidad y constancia.

Comparison of small and large deformation rheological properties of wheat dough and gluten

The rheological properties of dough and gluten are important for end-use quality of flour but there is a lack of knowledge of the relationships between fundamental and empirical tests and how they relate to flour composition and gluten quality. Dough and gluten from six breadmaking wheat qualities were subjected to a range of rheological tests. Fundamental (small-deformation) rheological characterizations (dynamic oscillatory shear and creep recovery) were performed on gluten to avoid the nonlinear influence of the starch component, whereas large deformation tests were conducted on both dough and gluten. A number of variables from the various curves were considered and subjected to a principal component analysis (PCA) to get an overview of relationships between the various variables. The first component represented variability in protein quality, associated with elasticity and tenacity in large deformation (large positive loadings for resistance to extension and initial slope of dough and gluten extension curves recorded by the SMS/Kieffer dough and gluten extensibility rig, and the tenacity and strain hardening index of dough measured by the Dobraszczyk/Roberts dough inflation system), the elastic character of the hydrated gluten proteins (large positive loading for elastic modulus [G'], large negative loadings for tan delta and steady state compliance [J(e)(0)]), the presence of high molecular weight glutenin subunits (HMW-GS) 5+10 vs. 2+12, and a size distribution of glutenin polymers shifted toward the high-end range. The second principal component was associated with flour protein content. Certain rheological data were influenced by protein content in addition to protein quality (area under dough extension curves and dough inflation curves [W]). The approach made it possible to bridge the gap between fundamental rheological properties, empirical measurements of physical properties, protein composition, and size distribution. The interpretation of this study gave indications of the molecular basis for differences in breadmaking performance.

Characterization of conductive polyprrole coated wool yarns

Wool yarns were coated with conducting polypyrrole by chemical synthesis methods. Polymerization of pyrrole was carried out in the presence of wool yarn at various concentrations of the monomer and dopant anion. The changes in tensile, moisture absorption, and electrical properties of the yarn upon coating with conductive polypyrrole are presented. Coating the wool yarns with conductive polypyrrole resulted in higher tenacity, higher breaking strain, and lower initial modulus. The changes in tensile properties are attributed to the changes in surface morphology due to the coating and reinforcing effect of conductive polypyrrole. The thickness of the coating increased with the concentration of p-toluene sulfonic acid, which in turn caused a reduction in the moisture regain of the wool yarn. Reducing the synthesis temperature and replacing p-toluenesulfonic acid by anthraquinone sulfonic acid resulted in a large reduction in the resistance of the yarn.

Reducing yarn hairiness with a modified yarn path in worsted ring spinning

The spinning geometry of a ring frame plays an important role, and the twist triangle is the critical region in ring spinning. Changes in the spinning geometry may affect yarn properties. This paper examines the idea of ring spinning with a "diagonal" yarn path, and the effect of such a path on yam properties, particularly hairiness. Both "left diagonal" and "right diagonal" yam arrangements are tried on a 24-spindle Cognetex FLC worsted ring frame. The hairiness results obtained from the Zweigle hairiness meter show that the right diagonal yam path produces yams of lower hairiness than the conventional ring spun yarn in almost all the hair length groups. Yam evenness and tenacity are not as sensitive to the change in yarn path. The mean spindle speed at break is also tested, and there is some deterioration in spinning efficiency with the right diagonal yarn path, particularly at higher spinning speeds. Results from this study may help explain variations in yarns spun on poorly aligned ring frames.

Mill specific prediction of worsted yarn performance

Different spinning mills use different raw materials, processing methodologies, and equipment, all of which influence the quality of the yarns produced. Because of many variables, there is a difficulty in developing a universal empirical/theoretical model. This work presents a multilayer perceptron algorithm (MLP) model for the purpose of building a mill specific worsted spinning performance prediction tool. Sixteen inputs are used to predict key yarn properties and spinning performance, including number of fibers in cross-section, unevenness (U%), thin places, neps, yarn tenacity, elongation at break, thick places, and spinning ends-down. Validation of the model on mill specific commercial data set shows that the general fit to the target values is good. Importantly, the performance of the MLP shows a certain degree of stability to different, random selections of independent test data. Subsequent comparison against the predicted outputs of Sirolan Yarnspec™ confirms the overall performance of the artificial neural network (ANN) method to be more accuratefor mill specific predictions.

The new solo-siro spun process for worsted yarns

The aim of this paper was to explore whether the properties of worsted yarns, especially hairiness, can be improved by combining the Solospun and Sirospun processes into a single Solo-Siro spun process. Wool fibres of 19 and 21 μm in average diameter were spun into 40 tex yarns at different twist levels, using the conventional ring, Sirospun and Solo-Siro spun systems, respectively. These yarns were then tested for a range of properties, including hairiness, tenacity, elongation and evenness, for comparison purposes. The statistical analysis results indicate that the hairiness (S3 value) of Solo-Siro spun yarns was significantly less than that of both Sirospun and normal ring spun yarns. In addition, the tenacity of the Solo-Siro spun yarns was higher than that of the normal ring spun yarns, while changes in yarn breaking elongation were not statistically significant. For the 21 μm wool, it was found that the evenness of Solo-Siro spun yarns deteriorated slightly in comparison with that of Sirospun and conventional ring spun yarns.

High technology nanocomposite fibres: Development of melt spun semi-aromatic polyamide nanocomposite fibres

Novel polyamide nanocomposite fibres have been produced by compounding semi aromatic Poly (m-xylene adipamide) (MXD6) and organophilic Montmorillonite (MMT). Partially orientated fibres (POF) of MXD6 nanocomposite were obtained by melt spinning on a multifilament fibre extrusion system at three different speeds. The effect of the drawing velocity
on the mechanical properties of the filaments has been determined. Tensile measurements indicated that the introduction of the nanoparticies by melt intercalation improves the tenacity and toughness of the resulting polyamide fibres. The microstructure of the nanocomposites was examined by X-ray diffraction and Transmission Electron Microscope (TEM) and shown to
be an exfoliated disordered structure. The thermal stability of MXD6 nanocomposites was analysed by thermo gravimetric analysis (TGA) suggesting stabilisation of the clay and the polymer systems above 450°C.

In-situ tensile properties of a ballooning staple yarn

This study investigated the tensile properties of a rotating or ballooning staple yarn. The results indicated that the effect of rotating speed on the tensile properties of a ballooning staple yarn was significant. As the yarn rotating speed increased, the tenacity of the rotating or ballooning yarn decreased, while the yarn breaking elongation increased. The effect of rotating speed on the tenacity of a ballooning staple yarn varied for different yarns. These results demonstrated that the breaking force of a ballooning yarn was much lower than the yarn breaking force obtained from normal tensile tests. These results provide new insight into the problems of yarn breakage in yarn spinning and twisting processes.

Fabrication of ultrafine powder from eri silk through attritor and jet milling

Fibroin protein derived from silk fibres has been extensively studied with exciting outcomes for a number of potential advanced biomaterial applications. However, one of the major challenges in applications lies in engineering fibroin into a  desired form using a convenient production technology. In this paper, fabrication of ultrafine powder from eri silk is reported. The silk cocoons were degummed and the extracted silk fibres were then chopped into snippets prior to attritor and air jet milling. Effects of process control agents, material load and material to water ratio during attritor milling were studied. Compared to dry and dry–wet attritor milling, wet process emerged as the preferred option as it caused less colour change and facilitated easy handling. Ultrafine silk powder with a volume based particle size d(0.5) of around 700 nm could be prepared following the sequence of chopping ➔ wet attritor milling ➔ spray drying ➔ air jet milling. Unlike most reported powder production methods, this method could fabricate silk particles in a short time without any pre-treatment on degummed fibre. Moreover, the size range obtained is much smaller than that previously produced using standard milling devices. Reduction in fibre tenacity either shortened the milling time even further or helped bypassing media milling to produce fine powder directly through jet milling. However, such reduction in fibre strength did not help in increasing the ultimate particle fineness. The study also revealed that particle density and particle morphology could be manipulated through appropriate changes in the degumming process.

Graphical Abstract:  Fabrication of eri silk powder using attritor and jet milling is reported. Volume based particle size d(0.5) of around 700 nm could be prepared following the sequence chopping ➔ wet attritor milling ➔ spray drying ➔ air jet milling. No pre-treatments were used and the particle size range obtained is much smaller than that previously produced using standard milling devices. Particle density morphology could be manipulated through appropriate changes of cocoon degumming conditions.

Investigation of yarn hairiness

Yarn hairiness affects not only the quality of products, but also the productivity in spinning and weaving. Too much yarn hairiness is undesirable for many end uses as well as the spinning and post spinning processes. The main aims of this project are to examine the hairiness features of various yarns and to reduce yarn hairiness. The thesis covers five related areas – hairiness assessment, factors affecting yarn hairiness, the hairiness of newly developed yarns, yarn hairiness reduction, and effect of yarn hairiness on the energy consumption in ring spinning. The worsted cashmere, pure wool and wool/cashmere blend yarns were employed to investigate the effect of some fibre parameters on the yarn hairiness. A single exponential distribution of the hair-length was confirmed first, using the data from the Zweigle G565 Hairiness Meter. A linear relationship was observed between the blend ratio and the hairiness indexes. In particular, the effect of fibre crimp or curvature on yarn hairiness is examined. The theory of yarn hairiness composition was also developed further. The effect of draft ratio and spindle speed on the hairiness of worsted wool yarn was examined next with a factorial experiment design. Several new hairiness indexes, namely the relative hairiness indexes, have been used to explain the results obtained. In the investigation of the hairiness of newly developed yarns, the hairiness of the Compact Spun and Roller-Jet-Spun yarns was examined first. The composition of the yarn hairiness, the hair-length distribution, and the effect of test speed on yarn hairiness were then studied. An important finding is that for both yarns, the predominant hairiness feature is the looped hairs. A comparison of the hairiness of Solospun yarns and the equivalent ring spun wool yarns was undertaken. The hair-length distribution of the Solospun yarn was examined first. The Solospun yarns used had fewer hairs in most hair-length groups and lower variations in hairiness. In addition, the effect of twist level and spindle speed on the hairiness of Solospun and conventional ring spun yarns has also been discussed. A novel approach of reducing yarn hairiness – spinning with a ‘Diagonal’ yarn path was examined next. Both ‘Left Diagonal’ and ‘Right Diagonal’ yarn arrangements were studied. A new finding is that the ‘Right Diagonal’ yarn path leads to reduced hairiness for the Z-twist yarn, while yarn evenness and tenacity are not as sensitive to the modified yarn path. The mechanism of hairiness reduction with the ‘Diagonal’ yarn path has been discussed. The spinning performance of “Right Diagonal” yarn arrangement has also been evaluated. Finally, the effect of yarn hairiness on the energy consumption in ring spinning has been investigated theoretically and experimentally. A theoretical model has been developed, which represents the first attempt at theoretically investigating the influence of yarn hairiness on energy consumption during the winding stage of ring spinning. The experimental results have generally confirmed predictions of this model. Recommendations for further research in this area have also been made in the concluding chapter of this thesis.

Processing and quality of cashmere tops for ultra-fine wool worsted blend fabrics

This study has focussed on three main areas. First, an evaluation of the physical attributes of cashmere tops available to commercial spinners; second, the influence of processing variables on the efficiency of producing cashmere tops from raw Australian cashmere; and third, the influence of design of cashmere ultrafine wool blends on the fibre curvature of tops. Testing the physical attributes of cashmere tops from traditional and new sources of supply, was followed by statistical analyses based on factors of origin, processor and other determinants. The analyses demonstrated important processor effects and also that cashmere from different origins shows commercially important variations in fibre attributes. It was possible to efficiently produce Australian cashmere tops with Hauteur, tenacity, extension, softness and residual guard hairs quality attributes equivalent to those observed in the best cashmere tops. The blending of cashmere with wool resulted in a reduction of the mean fibre curvature of the blend compared with the unblended wool. The present work demonstrated that the fibre curvature properties of blended low crimp ultrafine wool tops were closer to the properties of pure cashmere tops than were tops made from blended standard high crimp ultrafine wool. The attributes of textiles made from the relatively rare Australian low curvature cashmere could enhance the marketability of both Australian cashmere and low curvature wool.

Twist distribution in staple fibre yarns

Staple fibre yarns vary quite markedly in linear density (tex) along their length and the degree to which twist redistributes from thick to thin places will affect the strength, torque and extension behaviour of the yarn. Theory suggests that twist along worsted yarns should vary as 1/(tex)2 if fibres were locked in the structure, whereas themean torque of worsted yarns reported in the literature implies that twist should be proportional to 1/tex. This article examines twist distribution in ring-spun marl yarns, down to 5 mm resolution, as a function of linear density measured using a high-resolution capacitive sensor. It is found for moderate twist-level worsted yarns that twist is approximately proportional to 1/(tex)1.6. The results and theory provide a guide as to the effect the observed large variations in linear density will have on yarn properties such as tenacity and torque.