Philip Owende

Enhancement of BODIPY505/515 lipid fluorescence method for applications in biofuel-directed microalgae production.

This paper describes a microalgal cell lipid fluorescence enhancement method using BODIPY(505/515), which can be used to screen for lipids in wild-type microalgae and to monitor lipid content within microalgae production processes to determine optimal harvesting time. The study was based on four microalgae species (Dunaliella teteriolecta, Tetraselmis suecica, Nannochloropsis oculata, and Nannochloris atomus) selected because of their inherent high lipid content. An extended analysis was carried out with N. oculata due to the depressed fluorescence observed when compared with the other experimental strains. BODIPY(505/515) lipid fluorescence was determined for two solvent pre-treatment methods (DMSO and glycerol) and four staining condition parameters (analysis time, staining temperature, dye concentration, and algal cell concentration). It was found that lipid fluorescence of thick cell-walled microalgae, such as N. oculata, is significantly enhanced by both the pre-treatment methods and staining condition parameters, thereby significantly enhancing lipid fluorescence by ca. 800 times the base autofluorescence. The lipid fluorescence enhancement method provides a quick and simple index for in vivo Flow Cytometry quantification of total lipid contents for purposes of species screening or whole culture monitoring in biofuel-directed microalgae production.

A Method For Relating GPS Performance To Forest Canopy

Abstract This paper describes the development of a quantitative method of classifying forest canopy that can be related to degradation in Differential GPS (DGPS) performance. Using digital images taken vertically skywards at 20 sites within a forest on the east coast of Ireland, canopy cover was described using percentage sky obstruction (Op ), largest hole (DTmax ), and the fragmentation of sky view (DTp ) using pixel count and distance transform data. Statistical methods were used to produce three clusters which related to canopy cover in stands of Picea sitkensis and Picea contorta. DGPS data were then collected on 10 separate dates at the 20 sites, every two seconds for five minutes, and the two–dimensional standard deviation of the position fix was used to represent DGPS precision. The standard deviations ranged from 0.5 m to 9.7 m (compared to the manufacturer’s specification of approximately 1 m in the horizontal). Precision was found to be related to the total obstruction, the size of the largest hole in the canopy, and the fragmentation of the sky view. Where there was little obstruction (<20%) or fragmentation, the DGPS performance was effectively the same as outside the forest, open canopy caused a 2–3 fold degradation in precision, and closed canopy a 5–7 fold degradation. It is suggested that the methods presented could be used to rapidly relate DGPS performance to forest canopy, and therefore may be useful in pre–planning inventory mapping and future machine operations using guidance systems.

Biofuels from Microalgae: Towards Meeting Advanced Fuel Standards

Continued reliance on fossil fuel reserves as the primary energy resource is increasingly becoming unsustainable, owing to the need for: minimal exposure to the associate price volatility, reduction of greenhouse gas emissions by energy conservation, and deployment of cleaner and locally produced energy feedstock (including recovery from waste). Based on current knowledge and technology projections, third-generation biofuels (low input-high yielding feedstock) specifically derived from microalgae are considered to be viable alternative energy resource. They are devoid of the major drawbacks associated with first-generation biofuels (mainly terrestrial crops, e.g. sugarcane, sugar beet, maize and rapeseed) and second-generation biofuels (derived from lignocellulosic energy crops and agricultural and forest biomass residues). This chapter focuses on technologies underpinning microalgae-to-biofuels production systems, and evaluates the scale-up and commercial potential of biofuel production, including benchmarking of fuel standards. It articulates the importance of integrating biofuels production with the production of high-value biomass fractions in a biorefinery concept. It also addresses sustainability of resource deployment through the synergistic coupling of microalgae propagation techniques with CO2 sequestration and bioremediation of wastewater treatment potential for mitigation of environmental impacts associated with energy conversion and utilisation.

Influence of forest machine function on operator exposure to whole-body vibration in a cut-to-length timber harvester

The influence of machine function (tree felling and processing, and machine movement over the terrain) on operator exposure to whole-body vibration in a cut-to-length (CTL) timber harvester was evaluated. Vibrations were measured on the seat and the cabin chassis in three orthogonal (x, y, z) axes for the tree felling and processing, and during motion on a test track. It was found that the level of vibration transmitted to the operator during felling and processing was mainly affected by the tree size (diameter). For tree diameter at breast height (dbh) range of 0.25 – 0.35 m that was investigated, the vertical (z-axis) vibration component during processing increased by up to 300%, and increased by 50% during felling. However, the associated vibration levels were not sufficient to pose any serious health risks to the operator for an exposure limit of 8 h. Vibration at the operator seat and cabin chassis was predominant in the lateral (y-axis) and vertical (z-axis) respectively, during vehicle motion over the standard test track. Vibration peaks of approximately 0.20 and 0.17 ms−2 occurred at 5 and 3.2 Hz respectively.

Productivity and Cost of Mechanized Whole-Tree Harvesting of Fast-Growing Eucalypt Stands

Abstract The performance of alternative equipment for the whole-tree harvesting of eucalypt stands was evaluated, using data from five different commercial operations. The study covered three machines for felling and bunching, two for extraction (skidding), and two for combined delimbing, debarking and chipping. Productivity and operating cost models were evaluated for each of the machines, in order to estimate the net harvesting costs under varying forest stand and site conditions. It was found that under easy terrain conditions (flat terrain, dry ground), trees should be felled by threewheeled feller-bunchers and extracted by front-end loaders, as this combination had the lowest harvesting costs. Due to mobility limitations, this equipment may have to be replaced by tracked feller-bunchers and conventional skidders in steep terrain and/or soft ground. It was estimated that the cost of using the wheeled feller-buncher and the front-end loader system ranged between 16–22

Bearing capacity of forest access roads built on peat soils

per oven-dry-ton (odt), depending on tree size. If difficult terrain imposes a shift towards the second, more expensive combination, harvesting cost will increase by about 30% and may exceed 25

Characteristic loading of light mouldboard ploughs at slow speeds

/odt for an average tree weight less than 0.1 odt. Unit costs are inflated by 30% if the hog fuel is considered a by-product and the harvesting cost is charged entirely on the clean chip.

Performance of a Differential GPS in Dynamic Mode under Sitka Spruce Canopies

Abstract Significance of the thickness of peat substratum on the bearing capacity of forest access roads laid on peat soils in Ireland is evaluated. Bearing capacity of an experimental pavement was assessed on the basis of its surface deflection measured using a Benkelman beam. The mean deflections for winter, spring and summer seasons were 2.7, 5.1 and 5.4 mm, respectively, and the lower value for winter was attributed to the frozen pavement and lower soil moisture conditions. Pavement response in winter was a function of the interaction term of linear components of thickness of pavement layers and the peat substratum ( R 2 =0.67), while in spring ( R 2 =0.70) and summer ( R 2 =0.72), it also included a moderating quadratic term of thickness of the peat substratum. Deflection generally increased with thickness of pavement and the peat substratum, and effect of pavement thickness was pronounced under peat layer greater than 1000 mm which was attributed to inherent weakness of the pavements over such areas. It is suggested that thickness of the peat substratum may be a basis for developing specifications for timber haulage vehicles, or routeing of such traffic for minimal environmental impact.

Reaction forces of lightweight mouldboard ploughs at slow speeds of tillage in Nitosol, Vertisol and Ferralsol soils under two moisture conditions

Abstract A study on four mouldboard ploughs, that are commonly used with animal traction in Kenya, was conducted. Draught, suction and torsion loads were measured and specific draught evaluated in field tests on four sites with typical agricultural soil conditions. Draught and suction are the horizontal and vertical components of the reaction to soil force, respectively, while torsion is the resisting moment about the plough shank. The objective was to quantify these parameters and to study their characteristics under variable conditions at operation, at speeds up to 1.12 m/s and tillage depths between 0 and 150 mm in an attempt to optimize the design, selection and utilization of mouldboard ploughs for animal traction in Kenya. It was found that depth of tillage is the most critical factor, and draught and suction increased significantly with depth while specific draught increased or decreased depending on the soil type. Draught and specific draught increased significantly with speed. The increase in suction with depth probably implies an increased stability in the ploughing operation, while its reduction with speed indicates a potential instability of plough control with varying speeds. Consequently, aiming for steady motion in the utilization of animal traction may aid in the optimization. It was also found that ploughs with a high specific draught (kN/m) are expected to experience higher torsional loads on the shanks. The characteristic draught, specific draught and suction loads of the ploughs were described by quadratic functions in speed and depth of tillage with coefficients of determination ( R 2 ) ranging from 0.55 to 0.99. A significant difference in the coefficient of variation of draught loads in the three soil types probably implies that optimal duration for use of animal traction in tillage should be dependent on soil type.

DEVELOPMENT OF A TOWED RIG FOR TILLAGE STUDIES

Abstract Quantified, performance indicators for dynamic mode Differential GPS (DGPS) were collected at 31 sites established under 3 canopy classes (none, pre-first thinning and mature) of Sitka spruce stands in Ireland with varying altitude (100–500 m) and aspect. Canopy cover was quantified using total obstruction, size of largest opening and fragmentation of sky view. At sites with no canopy above 2 m, a mean precision of 1.5 m was recorded. Where canopy was present, precision ranged between 2.6 m and 2.8 m. The results indicated that in dynamic mode, differences in DGPS performance between canopy cover types were limited to a presence/absence effect. Loss of 3-dimensional operation (i.e. only 3 satellites in view) occurred more frequently than loss of differential correction signal and thus had a greater impact on recorded precision over the duration of the experiment. It was concluded from the data collected that the most versatile approach when using dynamic DGPS is to collect more (potentially poorer quality) data, rather than to apply a filter at the signal acquisition stage. The observations made, and the conclusions drawn in this paper are relevant to the forest industry in the selection and operation of DGPS equipment for dynamic tasks where ~ 2 m precision is required.