ACUE - Effective Teaching Practices: Module Reflections

Association of College and University Educators (ACUE) Course in Effective Teaching Practices, a nine-month online module certification program, provides an opportunity to learn how to design courses, engage learners, and establish a productive learning environment in both online and face-to-face teaching format. Upon completion of each module, course participants reflected on technique chosen, successes and/or challenges, and plans for implementation

The impact of the leather manufacturing process on bacterial growth

Hides and skins used as a raw material for leather manufacture may be contaminated with various microbial species including potential pathogens. Many bacterial species such as Bacillus, Staphylococcus, Micrococcus and Pseudomonas were isolated from raw hides/skins, and hides/skins at different stages of leather making process. The extreme environmental conditions present during a conventional tanning process due to hazardous chemicals may prevent the growth of bacteria present on hides/skins. On the other hand, partial or total replacement of the hazardous chemicals with non-hazardous chemicals, during a best available technologies (BAT) process, may provide suitable conditions for microbial growth in tannery effluent and hides/skins. Therefore, the aim of the project was to determine the survival and growth of the various bacterial species during the conventional and BAT leather-making processes. The beamhouse and tanning stages were studied, as the majority of the environmental pollution occurs during the early stages of the leather making process. Both the pre-soaking and soaking stages during the conventional and BAT leather-making processes provided suitable conditions for bacterial (Bacillus cereus, Pseudomonas aeruginosa and Staphylococcus spp.) growth and proliferation. The results showed a significant reduction in the number of B. cereus found during the conventional and BAT unhairing processes. Limited B. cereus growth was observed during the subsequent reliming process. Bacillus cereus growth also occurred during the deliming and bating processes (conventional and BAT), followed by a decrease during the conventional and BAT pickling processes. No B. cereus colonies were isolated during the chrome tanning process. Growth of P. aeruginosa was inhibited during both the unhairing and reliming stages of the conventional and BAT leather making processes. A reappearance and recovery of P. aeruginosa in the subsequent deliming and bating (conventional and BAT) processes, indicated that deliming and bating processes may provide suitable growth conditions for P. aeruginosa. On the other hand, both the conventional and BAT pickling processes, and the chrome tanning processes hindered P. aeruginosa growth. Staphylococcus spp. were present throughout the conventional and BAT leather-making processes. A large reduction in the number of Staphylococcus spp. was observed during the unhairing and reliming processes (conventional and BAT). Growth of Staphylococcus spp. occurred during the subsequent deliming, bating, pickling and chrome tanning stages for both the conventional and BAT leather-making processes. The biochemical assays for bacterial identification confirmed the presence of B. cereus, P. aeruginosa and Staphylococcus spp. during the leather processing. The pulsed-field gel electrophoresis (PFGE) method of DNA fingerprinting confirmed that the bacterial species isolated during the leather manufacturing processes were the inoculated B. cereus and P. aeruginosa, and no alteration of the DNA of above-mentioned bacteria occurred during the processing. Overall, the research showed that bacterial species are capable of surviving during both the conventional and BAT leather-manufacturing processes. The bacterial species prefer the environmental conditions during the pre-soaking and soaking processes, while the unhairing and reliming processes did not favour the growth of bacterial species. Bacterial colonies were enumerated during the deliming and bating processes indicating that the unhairing and reliming processes did not cause total destruction of the bacterial cells. Alternatively pickling and chrome tanning processes were found to have suppressed the growth of bacterial colonies

Factors affecting methylmercury biomagnification by a widespread aquatic invertebrate predator, the phantom midge larvae Chaoborus

MeHg biomagnification by the phantom midge Chaoborus in relation to MeHg concentrations in their prey and its migratory behavior was investigated in two Canadian Precambrian Shield lakes. Three Chaoborus species with contrasted migratory behavior were collected in a fishless and a fish-inhabited lake. All species accumulated MeHg through their ontogenic development. In the lake inhabited by fish, all instars of Chaoborus punctipennis displayed a marked migratory behavior and were unable to biomagnify MeHg, whereas in the fishless lake, Chaoborus americanus and Chaoborus trivittatus biomagnified MeHg. Reduced biomagnification capacity of C. trivittatus, the coexisting species living with C. americanus, was also ascribed to a progressive vertical segregation with age. Growth dilution, amount and type of prey items or trophic position could not explain the different patterns of biomagnification. Our findings demonstrate that the most common invertebrate predator of temperate planktonic food webs can biomagnify mercury, contrarily to previous reports

Methods of isolation and identification of pathogenic and potential pathogenic bacteria from skins and tannery effluents

Currently there is no standard protocol available within the leather industry to isolate and identify pathogenic bacteria from hides, skins or tannery effluent. This study was therefore carried out to identify simple but effective methods for isolation and identification of bacterial pathogens from the effluent and skins during leather processing. Identification methods based on both phenotypic and genotypic characteristics were investigated. Bacillus cereus and Pseudomonas aeruginosa were used as indicator bacteria to evaluate the isolation and identification methods. Decontaminated calfskins were inoculated with a pure culture of the above mentioned bacterial species followed by a pre-tanning and chromium tanning processes. Effluent samples were collected and skins were swabbed at the end of each processing stage. Bacterial identification was carried out based on the phenotypic characteristics; such as colony appearance on selective solid media, cell morphology following a standard Gram-staining and spore staining techniques, and biochemical reactions, e.g., the ability of a bacterial species to ferment particular sugars and ability to produce certain enzymes. Additionally, an identification system based on bacterial phenotypic characteristics, known as Biolog® system was applied. A pulsed-filed gel electrophoresis (PFGE) method for bacterial DNA fingerprinting was also evaluated and used for the identification of the inoculated bacteria. The methods described in the study were found to be effective for the identification of pathogenic bacteria from skins and effluent

Feasibility of ultrafast picosecond laser cleaning of soiling on historical leather buckles

The aim of the research is to present a system recently developed and used for automated cleaning of artworks and to examine the suitability of using this ultrafast and precise computed-scanning picosecond laser (1064 nm) with a repetition rate of 10 kHz and a temporal pulse length of 10 ps for the removal of soiling from leather buckles without damaging the leather substrate. Preliminary tests will be performed with the model artificially aged vegetable tanned samples to determine the leather damage threshold fluence and the soiling ablation threshold fluence before using a laser for the removal of the soiling from a historical leather buckle. As laser cleaning requires a physical parameterization for optimization of cleaning accompanied with an assessment of the morphological and chemical changes of leather, an investigations were performed to determine the leather damage and ablation threshold fluences of artificially aged and historical vegetable tanned leather using a number of analytical techniques including differential scanning calorimetry, optical microscopy, scanning electronic microscope with energy dispersive X-ray analysis, colorimetry and Fourier transform infrared spectroscopy have been used. Following optimization trials of the picosecond laser cleaning parameters on model leather samples, satisfactory removal of the soiling over the historical leather surface is achieved

Closed-loop and chromium-free leather for the circular economy through refining sustainably available plant food waste

Currently, 80% (1700 km2) of global leather manufacture is tanned with chromium (III) salts, which are not renewable and problematic to recover at end-of-life (Covington 2007). Commercial vegetable tanning agents are extracted from cultivated stocks, which are insufficient to replace the current consumption of chromium (III) salts. Further expansion of existing plantations is not a sustainable method to generate sufficient tannin extracts to meet current demands. Therefore, alternative bio-based waste sources are required to effectively reuse resources and reduce the need for new fossil-based inputs and reduce the environmental footprint of leather manufacture. Literature supports the presence of tannins in coffee waste. Low et al (2015) and Bhoite et al (2013) confirm the presence of both condensed and hydrolysable tannins with C13 NMR and MS data. This observation can be extended to many waste streams in the food and beverage sector. Underpinning tanning application has been demonstrated through trials by Baskar at ICLT, which shows the extracted coffee waste replaces conventional veg tannins which includes both tanning and retanning stages. Typical concentrations of tannins required to fully tan are more than 30% of the hide weight, therefore, the use of waste sources has the potential to replace a significant quantity of leather processing chemicals. Currently at TRL 3, the project aim is to develop a scalable leather manufacturing process with tannins extracted from food and beverage wastes thus replacing Cr and plantation crop tanning agents

What’s Hiding in the Spine? A Study of Adhesives in Medieval Books Using Mass Spectrometry

Glues, and in particular glued spines, are notable features of late medieval European books, yet little research has been done into how they were sourced, produced, and used. In this article we present preliminary results from using the paleoproteomic methods of Electromagnetic Zooarchaeology through Mass Spectrometry (eZooMS) and Peptide Mass Fingerprinting (PMF) to identify the source species for animal glues used in late medieval books. We first introduce readers to the principal kinds of glue used in medieval craftsmanship and what is known about their use in bookbinding, principally from the discipline of book conservation. We describe the micro-sampling methods of eZooMS, in which a PVC eraser is rubbed gently on the surface of the book. We then describe the process through which we tested and fine-tuned our sampling methods on eight medieval books held in Canadian repositories, addressing some of the challenges we faced, potential further uses or expansions upon the technique, and the benefits of our collaborative approach to such “manuscientific” studies

A new formulation for the treatment of acid-deterioration (Red Rot) in historic leathers

Conservation of acid-deteriorated historic leather (also commonly known as red rot) is an on-going concern as current treatment options are limited. Various products such as aqueous-based buffer salts, imidazole, ammonia vapour and aluminium di(isopropoxide) acetoacetate ester chelate (referred to as aluminium alkoxide in this study) have been used to treat acid-deterioration in historic leathers. Among the various products studied, aluminium alkoxide was found to be the most effective. However the effect of aluminium alkoxide when applied on its own may be limited due to its short-term stabilisation effect. A new formulation consisting of aluminium alkoxide and 5-ethyl-1-aza-3, 7-dioxabicyclo [3.3.0] octane (oxazolidine II) was used to treat acid-deterioration in historic leather. Acid-deteriorated leathers were treated with the new formulation and aged further by exposure to an acidic environment at 40°C and 30% relative humidity for up to 12 weeks. The acidic environment was created using sulfur dioxide and nitrogen dioxide. Corresponding untreated acid-deteriorated historic leathers were used as a negative control. The impact of the treatments and artificial ageing was determined by measuring the hydrothermal stability of the leather samples using differential scanning calorimetry (DSC) and pH of the aqueous extract. The results obtained showed that the formulation has collagen-stabilising properties, acid-buffering capacity as well as the capability to provide long-term protection against an artificially-created acidic environment

Use of aluminium alkoxide and oxazolidine II to treat acid-deteriorated historic leather

This study was undertaken to develop a product that will potentially delay the progress of deterioration of acid-deteriorated historic leather. Acid-deteriorated leather samples were treated with a new formulation consisting of aluminium di(isopropoxide) acetoacetate ester chelate (aluminium alkoxide) and 5-ethyl-1-aza-3,7-dioxabicyclo[3.3.0]octane (oxazolidine II). The leather samples were also treated with oxazolidine II and aluminium alkoxide separately to compare the effectiveness of these reagents against the new formulation. Untreated leather samples were used as a negative control. Acid-deteriorated leather samples treated with Cellugel®, aluminium alkoxide and the new formulation along with corresponding untreated leather samples were also subjected to accelerated ageing in order to investigate the longevity of the treated leather. The impact of the treatments and accelerated ageing was determined by measuring the hydrothermal stability of the leather and pH of the aqueous extract. The formulation showed a potential to provide the acid-deteriorated historic leather with long-term protection against an artificially-created acidic environment