Graduate School of Engineering

1 Graduate Student, Graduate School of Engineering, Hokkaido University, Sapporo, Japan 2 Professor, Graduate School of Engineering, Hokkaido University, Sapporo, Japan 3 Former Graduate Student, Graduate School of Engineering, Hokkaido University, Sapporo, Japan ...

The proper long-term performance of key bridge components such as bearings, expansion joints, dampers and seismic isolators is an important factor in the life-cycle quality control of new and existing bridge infrastructure. Laboratory testing of these components in accordance with national and international standards can very helpful in ensuring good performance, but the testing that can find application is very varied, as demonstrated with reference to sample completed testing procedures – illustrating the benefit of consulting with an experienced practitioner as required.

As the expectations of populations all around the world continue to increase in relation to the resilience of their bridges and buildings to hazards such as seismic events, the need for appropriate solutions – which can be applied both to new structures and to existing ones – grows accordingly. A wide range of solutions is available, such as shock absorbers and shock transmission units which can be used to dampen or optimally transmit forces that would otherwise damage a structure, and seismic isolators which can protect buildings and bridges from destructive ground motions. Expansion joints can be equipped with features that protect a bridge, at its key movement nodes, from damage due to larger-than-expected movements, and structural health monitoring (SHM) can be used to enable hazards to be identified and to provide immediate notification of any event that might make a structure unsafe. Various such methods of enhancing resilience of structures to seismic and other hazards are de...

This paper investigates the effectiveness of the use of seismic isolation devices on the overall 3D seismic response of curved highway viaducts with an emphasis on expansion joints. Furthermore, an evaluation of the effectiveness of the use of cable restrainers is presented. For this purpose, the bridge seismic performance has been evaluated on four different radii of curvature, considering two cases: restrained and unrestrained curved viaducts. Depending on the radius of curvature, three-dimensional non-linear dynamic analysis shows the vulnerability of curved viaducts to pounding and deck unseating damage. In this study, the efficiency of using LRB supports combined with cable restrainers on curved viaducts is demonstrated, not only by reducing in all cases the possible damage, but also by providing a similar behavior in the viaducts despite of curvature radius.

This paper investigates the possibility of pounding, deck unseating and tangential joint residual damage depending on the curvature radius. Furthermore, an evaluation of the effectiveness of the use of cable restrainers on the overall 3D seismic response of highway viaducts is presented. For this purpose, the bridge seismic performance has been evaluated on four different radii of curvature, considering two cases: restrained and unrestrained curved viaducts. Depending on the radius of curvature, three-dimensional non-linear dynamic analysis shows the vulnerability of curved viaducts to pounding and deck unseating damage. In this study, the efficiency of using cable restrainers on curved viaducts is demonstrated, not only by reducing in all cases the possible damage, but also by providing a similar behavior in the viaducts despite of curvature radius.

This paper investigates the effectiveness of the use of seismic isolation devices on the overall 3D seismic response of curved highway viaducts with an emphasis on expansion joints. Furthermore, an evaluation of the effectiveness of the use of cable restrainers is presented. For this purpose, the bridge seismic performance has been evaluated on four different radii of curvature, considering two cases: restrained and unrestrained curved viaducts. Depending on the radius of curvature, three-dimensional non-linear dynamic analysis shows the vulnerability of curved viaducts to pounding and deck unseating damage. In this study, the efficiency of using LRB supports combined with cable restrainers on curved viaducts is demonstrated, not only by reducing in all cases the possible damage, but also by providing a similar behavior in the viaducts despite of curvature radius.

The results show that the bridge equipped with seismic isolation bearing system shows a high amount of energy dissipation. The purpose of the present study is to analyze the overall performance of continuous curved highway viaducts with different bearing supports, with an emphasis on the effectiveness of seismic isolation based on lead rubber bearing and hedge reaction force bearing system consisted of friction sliding bearing and rubber bearing. The bridge seismic performance has been evaluated on six different cases with six bearing models. The effects of the different arrangement of bearing on the deck superstructure displacements, the seismic damage at the bottom of the piers, movement track at the pier-s top and the total and strain energies absorbed by the structure are evaluated. In conclusion, the results provide sufficient evidence of the effectiveness on the use of seismic isolation on steel curved highway bridges.

The gene encoding an FMN-dependent NADH azoreductase, AzrG, from thermophilic Geobacillus stearothermophilus was cloned and functionally expressed in recombinant Escherichia coli. Purified recombinant AzrG is a homodimer of 23 kDa and bore FMN as a flavin cofactor. The optimal temperature of AzrG was 85 degrees C for the degradation of Methyl Red (MR). AzrG remained active for 1 h at 65 degrees C and for 1 month at 30 degrees C, demonstrating both superior thermostability and long-term stability of the enzyme. AzrG efficiently decolorized MR, Ethyl Red at 30 degrees C. Furthermore, the enzyme exhibited a wide-range of degrading activity towards several tenacious azo dyes, such as Acid Red 88, Orange I, and Congo Red. These results suggested the sustainable utilization of G. stearothermophilus as an azo-degrading strain for AzrG carrying whole-cell wastewater treatments for azo pollutants under high temperature conditions.

Poly[3-hydroxybutyrate-co-3-hydroxyvalerate(3HV)] was produced in recombinant Escherichia coli LS5218 from ruthenium-catalyzed cellulose hydrolysate and propionate. The strain was found to be resistant to 5-hydroxymethylfurfural (5-HMF), which is a major inhibitory byproduct generated in the cellulose hydrolysis reaction. The 3HV fraction was successfully regulated in the range of 5.6–40 mol%.

The biopolymer, polylactic acid (PLA), which is produced from renewable carbon resources, can be used as a plastic replacement for the petrochemical-derived plastics that cause global warming and petroleum depletion problems. The aim of this study was therefore to produce the useful LA-based polyester using the inexpensive carbon sources derived from lignocellulosic biomass. The utilization of lignocellulosic biomass has advantages over the most used starch and sugar-based carbon sources in that lignocellulosic biomass is inedible and inexpensive. These advantages make lignocellulosic biomass an attractive carbon source in establishing a biorefinery for the production of LA-based polymers. PLA is a biocompatible and biodegradable material employed in various applications. Recently, LA-based polyester production system has been established in microorganisms using a lactate-polymerizing enzyme (LPE). This system was achieved by cultivating cells expressing LPE to produce LA-based polymers from refined glucose.

Background: The most common milk handling containers used by dairy actors along the informal milk value chain in developing countries are plastics jerry cans which are difficult to effectively be cleaned thus contributing immensely to milk contamination and consequently post-harvest losses. The aim of this study was to determine the effectiveness of some common cleaning regimes used by the dairy actors in Kenya against reduction of surface microbial load on jerry cans. Milk handling plastic jerry can containers (n = 16) were obtained from dairy actors and then subjected to four different commonly used cleaning regimes alongside a control experiment of aluminium cans (n = 4). These containers were aseptically swabbed in three replicates before and after the application of a cleaning regime and the swabs (n = 120) analyzed for Total Viable Count (TVC), Total Coliform Count (TCC) and Lactic Acid Bacteria (LAB). The quantitative mean difference of the bacterial load reduction between before and after the application of a cleaning regime was used as the measure of its effectiveness. Results: The study found out that irrespective of the cleaning, the type of container was significant (P < 0.001) in the reduction of microbial contaminants, whereby the aluminium cans had the highest microbial load reduction of 86, 85 and 96 % for TVC, TCC and LAB respectively as compared to 40, 28 and 42 % for TVC, TCC and LAB respectively for plastic jerry cans. The use of a commercial scourer in the cleaning was found to significantly reduce (P < 0.05) only TVC and TCC. Conclusions: The results from this study explains the unsuitability of plastic jerry cans in handling of milk and a risk factor for milk post-harvest losses in Kenya through microbial contamination.

Pastoral communities in Kenya have used smoke from specific herbs as a technique of disinfecting milk-handling containers, preserving milk and to impart a characteristic desired flavour to raw camel milk. The smoking is expected to extend the shelf life of the camel milk, despite the high environmental temperatures (>28°C). The aim of this study was to determine the antimicrobial effect of smoke on plastic milk-handling container surfaces and determine the efficacy of smoking as a preservation method. Smoked plastic milk-handling containers (n = 25) were conveniently collected from pastoral community households in Isiolo County, Kenya. Two containers were prepared by either washing and rinsing using hot water to be the negative control or rinsing and disinfecting using a chlorine-based agent to be the positive control. The inner surfaces of the containers were aseptically swabbed and analysed for total viable count (TVC), total coliform count (TCC), and lactic acid bacteria (LAB). The TVC from the smoked containers was 4.64 ± 0.43 log 10 cfu/cm 2 while the TCC was 4.00 ± 0.66 log 10 cfu/cm 2 and the LAB were 3. 75 ± 0.59 log 10 cfu/cm 2 , and those of the negative control (plain-water-washed non-smoked plastic container) were 5.99 ± 1.03, 5.07 ± 0.91, and 4.81 ± 0.81 log 10 cfu/cm 2 for TVC, TCC, and LAB, respectively. The mean microbial load of milk bulked in smoked containers was 5.10 ± 0.96, 3.61 ± 2.13, and 3.84 ± 2.22 log 10 cfu/ml for TVC, TCC, and LAB, respectively, while the mean microbial load of milk bulked in chlorine-disinfected containers was 5.23 ± 1.11, 2.46 ± 2.18, and 2.04 ± 1.35 log 10 cfu/ml for TVC, TCC, and LAB, respectively. The common types of microbes were Gramnegative rods (57.3 %), Gram-positive rods (25.5 %), and Gram-positive cocci (17.2 %). The most prevalent coliforms from all types of the containers and milk were Escherichia coli spp. and Enterobacter spp. while the LAB were Lactobacillus spp. and Lactococcus spp. Therefore, smoking of milk-handling containers can be recommended as an effective method for disinfection of milk-handling containers and as a method of preservation of camel milk in the arid and semi-arid areas of Kenya, where the cold chain or processing infrastructure is poor.

Jam is a type of a fruit preserve/spread usually made from all types of fruits, sugar, and pectin for consumption during the off-season. Jams are famous mainly due to their availability, organoleptic properties, and low cost that are usually canned or sealed after production in sterilized bottles (Muresan, Pop, Muste, Scrob, & Rat, 2014). Jam was traditionally prepared to preserve seasonal fruits by heating them with sugar and pectin in the fruit (Patrick, 1982). Currently, fruit preserves are made both commercially and in homebased operations. The jam is prepared by chopping the fruits then followed by cooking with sugar and pectin until the required consistency is achieved, after which it is packed in sterilized jars or cans (Ihekoronye, 1999). Pineapple is one fruit that is used for making jam that is an excellent source of vitamin C and manganese among other nutrients.

 Local marketing of raw milk has been increased in the low and middle income countries.  Emerging economies are at risk of illnesses from food-borne pathogens due to poor milk handling.  The regulatory bodies from low and middle income countries are usually underfunded.  It is necessary for the low and middle income countries to invest in infrastructures and establishments.

The objective of the study was to evaluate the physicochemical, antioxidant and sensory properties of fermented milk beverage with added prebiotic and caja-manga pulp. Three milk beverage formulations were prepared, with 25% and 30% caja-manga pulp and a control (pulp-free) formulation. The following were evaluated: physicochemical characteristics (pH, acidity, proximal composition, color), total phenolics, antioxidants (DPPH, ABTS, FRAP), and sensory properties (preference, acceptance, and purchase intention). Differences were observed between the beverages regarding the physicochemical characteristics, and the composition varied according to the pulp concentration added. The beverages with pulp presented higher phenolic content than control formulation. The formulations with 25% and 30% pulp presented antioxidant capacity by the DPPH method with no significant difference between them. However, it was not possible to observe the antioxidant capacity of the pulp-free beverage for this method. No antioxidant capacity was detected by the ABTS and FRAP methods for all beverages studied. The milk beverages presented good sensory acceptance and antioxidant capacity due to the bioactive compounds present in the caja-manga pulp, which contributes to the claim of functionality of this food.

Background: Consumer interest in convenience foods is a new trend worldwide that is expected to increase due to busy lifestyles. Studies have shown that sweet potato has unique nutrients, which if incorporated into cheese, can make it a functional food. Food product development process requires that before a product is commercialized, it is subjected to consumer acceptability and shelf-life tests. Objective: The objective of this study was to determine the sensory acceptability and shelf life of mozzarella cheese that was enriched with orange-fleshed sweet potato to improve fiber content. Methods: Mozzarella cheese was prepared with orange-fleshed sweet potato powder at 0% up to 5.5% at intervals of 0.5% and a seven-point hedonic scale was used to evaluate product acceptability based on colour, aroma, acidity, texture, and fibrousness. Cluster analysis and principal component analysis were carried out using Minitab® software. For shelf life, total coliform count, E. coli, and yeasts...

This study evaluated the diversity, distribution and abundance of grasshoppers and locusts in three ecological zones of Nakuru County, Kenya. A total of 456 individuals belonging to Acrididae family (93.4% with 16 species) and Pyrgomorphidae family (6.6% with 2 species) were recorded. Ailopus thalassinus was the most abundant (27.4%) and distributed species. There were 5 dominant and 3 rare species (in zone II only). Abundance was highest in zone II (47%) and lowest in zone IV (24.3%) but was not significantly different (p&gt; 0.05) among the zones. Species diversity and abundance were highly correlated (r = 0.99, d.f. = 2, p&lt;0.05). Zone II and III, and Zone II and IV had highest species similarity (Jaccard and Sørensens similarity indices), while zone III and IV had the lowest. Zone II had the highest diversity (2.45), while zone III and IV had the lowest (1.37 and 1.30, respectively) at t=0.04 (Shannon-Wiener indices). Species were distributed more equitably (evenness) in zone ...

Many spontaneously fermented milk products are produced in Kenya, where they are integral to human diet and play a central role in enhancing food security and income generation. Some of these products have demonstrated therapeutic and probiotic effects although recent reports have linked some to death, biotoxin infections, and esophageal cancer. These products are mostly processed from poor quality raw materials under unhygienic conditions resulting to inconsistent product quality and limited shelf-lives. Though very popular, research on their processing technologies is low. This review provides a comprehensive summary of the most common spontaneously fermented milk products from Kenya including Mursik, Kule naoto, Amabere amaruranu and Suusa. Their production challenges and future perspectives are highlighted; emphasizing the need for application of high throughput biotechnologies in their study. Available literature on their microbiology, biochemistry, and chemical composition is summarized. Moreover, knowledge on the value of clean starting raw material, fermentation parameters definition, and employment of standard equipment are discussed.