The Preparation of Barium Hexaferrite Coatings Using HVOF

Thick coatings of barium hexaferrite with the compositions BaFe₁₂O₁₉ and BaCoTiFe₁₀O₁₉ were prepared using high-velocity oxygen-fuel (HVOF) spraying technology. Nanocrystalline precursors embedded in an amorphous matrix were obtained on both Fe and glass–ceramic substrates. To promote the crystallization of the hexaferrites, the coatings were annealed at 800°–1000°C, and single-phase coatings were obtained at 1000°C. The crystallization process was studied with X-ray powder diffraction and with electron microscopy. The magnetic measurements of the coatings were carried out in a static field and at high frequencies. The magnetization of the coatings increased with the annealing temperature to above 50 emu/g for both compositions. The coercivity of BaFe₁₂O₁₉ increased with the annealing temperature to above 2400 Oe, whereas the coercivity of BaCoTiFe₁₀O₁₉ decreased from over 800 Oe, for the as-deposited sample, to 400 Oe for the sample annealed at 1000°C. A minimum 90% absorption was calculated for the BaFe₁₂O₁₉ coatings with thicknesses of 0.15–0.25 mm at around 47 GHz and for the 1–4-mm-thick coatings of BaCoTiFe₁₀O₁₉ at 3–9 GHz.     

Transesterification of trimethylolpropane and rapeseed oil methyl ester to environmentally acceptable lubricants

Biodegradable trimethylolpropane [2-ethyl-2-(hydroxymethyl)-1,3-propanediol] esters of rapeseed oil fatty acids were synthesized by transesterification with rapeseed oil methyl ester both by enzymatic and chemical means, both in bench and pilot scales. Nearly complete conversions were obtained with both techniques. A reduced pressure of about 2 to 5 kPa, to remove the methanol formed during transesterification, was critical for a high product yield. The quantity of added water was also critical in the biocatalysis. Candida rugosa lipase was used as biocatalyst and an alkaline catalyst in chemical transesterifications. In biocatalysis the maximum total conversion to trimethylolpropane esters of up to 98% was obtained at 42°C, 5.3 kPa, and 15% added water. The maximum conversion of about 70% to the tri-ester was obtained at the slightly higher temperature of 47°C. The reaction time was longer in the biocatalysis, but considerably higher temperatures were required in chemical synthesis. In the chemical synthesis tri-ester yields increased when the temperature was first held at 85 to 110°C for 2.5 h and subsequently increased to up to 120°C for 8 h. The trimethylolpropane esters obtained were tested as biodegradable hydraulic fluids and compared to commercially available hydraulic oils. The hydraulic fluids based on trimethylolpropane esters of rapeseed oil had good cold stability, friction and wear characteristics, and resistance against oxidation at elevated temperatures.     

The salmon-peloton: Hydraulic habitat shifts of adult Atlantic salmon (Salmo salar) due to behavioural thermoregulation

In recent decades, there has been an increase in conservation and restoration projects targeting Atlantic salmon (Salmo salar – AS), as populations in eastern Canada decline. Missing however, is an understanding of thermo-hydraulic habitat use by adult AS during summer, and thus the actual benefits of altering in-river physical structures. Here, we illustrated how optical and thermal infrared (TIR) imagery acquired from a UAV can be used in concert with in-situ depth and velocity data to map adult AS and develop models of thermo-hydraulic habitats in the Miramichi River, New Brunswick. We found during normal temperature conditions (<19°C) boulder proximity, depth, velocity, and Froude number, a non-dimensional hydraulic metric, were key parameters that characterized adult AS habitat. However, during behavioural thermoregulation events (>19°C), proximity to the cool thermal plume and Froude number were critical controls on habitat use. We also observed AS forming a distinct geometric formation during behavioural thermoregulation events, and term this formation a “thermal-peloton”; in reference to competitive cycling in which groups of cyclists pack together. The primary function of the peloton is undoubtedly to reduce thermally induced stressed; however, we conceptualize that the geometry of the peloton attenuates hydraulic-drag, and reduces the energetic expenditure of individuals practicing behavioural thermoregulation. These data provide a blue print for Atlantic salmon restoration work. The use of UAV-based sensors has the potential to initiate a paradigm shift for river sciences.     

Interannual variation in spawning success of striped bass (Morone saxatilis) in the Saint John River,New Brunswick

Barriers such as dams have been cited as a serious threat to striped bass survival, especially when they affect or impede migration and access to spawning grounds. On the Saint John River, New Brunswick, the installation of the large Mactaquac Dam in the immediate vicinity of a historic striped bass spawning location was suspected to have caused the arrest of striped bass reproduction and the collapse of the native striped bass population. In 2014, juvenile striped bass of confirmed Saint John River origin were documented in the river for the first time since 1979. In the current study, we examined juveniles from 6 years of sampling to determine corresponding years of successful recruitment. We also tracked adult striped bass matching the ancestry of native Saint John River juveniles to determine the timing and location of spawning. Over 5 years, we observed an annual upstream migration by adult striped bass to historic spawning areas near Fredericton, identified a dominant year class of Saint John River origin juveniles reproduced in 2013, and linked the apparent successful production of year classes to definable discharge conditions, that is, extended periods of sustained flow >36 hr downstream from the Mactaquac Dam. The results of this study suggest important first management actions towards recovering and sustaining the re‐discovered striped bass population in the Saint John River, New Brunswick.     

TUTWLAN – QoS Supporting Wireless Network

Quality of Service (QoS) support has generally been lacking from WPAN and WLAN technologies, which has motivated the research of TUTWLAN. Design objectives have been relatively simple network architecture and capability to support real time services ranging from sensor data to multimedia streaming. The main TUTWLAN entities for QoS support are the Medium Access Control (MAC) protocol called TUTMAC and TUTWLAN Access Point (AP). The channel access is based on dynamic reservation Time Division Multiple Access (TDMA). TUTWLAN is shown to be suitable for wireless home and office applications. It provides flexibility, interoperability and availability of services exceeding the recent QoS proposals that has been accounted at the standardisation bodies for standard wireless technologies. This revised version was published online in September 2006 with corrections to the Cover Date.     

Lipid effects of an intrauterine levonorgestrel device or oral vs. vaginal natural progesterone in post-menopausal women treated with percutaneous estradiol

The clinical characteristics of 191 adolescent inpatients were examined in relation to frequency of previous suicide attempts, predictors of suicide attempts prior to hospitalization, and lifetime suicide attempts. Overall, more than 50% of the adolescent inpatients had attempted suicide during their lifetime, and of these more than half (58%) had made more than one attempt. Approximately half of the suicide attempters had made a serious attempt prior to hospitalization. Girls reported higher levels of depressive symptoms and suicidal ideation than boys, in addition to having attempted suicide prior to hospitalization (33%) or during lifetime (37%) more often than the boys (13% and 26%, respectively). Although about two thirds of the adolescent inpatients reported that they had received some help after a suicide attempt, approximately half of the repeaters had not received any help. The results of multivariate analyses showed that suicide attempts made prior to hospitalization were predicted by depressive symptom levels and a clinical diagnosis of depressive disorder, whereas frequency of lifetime suicide attempts was predicted by suicidal ideation levels and having a family member or a friend who had attempted (or committed) suicide. The high prevalence of lifetime and repeated suicide attempts among the psychiatric inpatients underscores the importance of identifying risk factors in the clinical evaluation of adolescent suicide attempters.     

Determinants of household energy consumption in India

Improving access to affordable modern energy is critical to improving living standards in the developing world. Rural households in India, in particular, are almost entirely reliant on traditional biomass for their basic cooking energy needs. This has adverse effects on their health and productivity, and also causes environmental degradation. This study presents a new generic modelling approach, with a focus on cooking fuel choices, and explores response strategies for energy poverty eradication in India. The modelling approach analyzes the determinants of fuel consumption choices for heterogeneous household groups, incorporating the effect of income distributions and traditionally more intangible factors such as preferences and private discount rates. The methodology is used to develop alternate future scenarios that explore how different policy mechanisms such as fuel subsidies and micro-financing can enhance the diffusion of modern, more efficient, energy sources in India.