The stress and metabolic responses of juvenile Atlantic cod Gadus morhua L. to an acute thermal challenge

Survival, oxygen consumption (M_O2), total plasma cortisol and glucose levels and gill heat-shock protein 70 (hsp70) expression were measured in 10 and 50 g juvenile Atlantic cod Gadus morhua during an acute temperature increase (2° C h⁻¹) to their critical thermal maximum. Ninety three per cent of the fish in both size classes survived to 24° C; however, mortality was 100% within 15 min of reaching this temperature. The M_O2 for both size classes increased significantly with temperature, reaching peak values at 22° C that were c. 2·8-fold those of control (10° C) fish. Resting plasma cortisol and glucose levels were lower in 10 g as compared to 50 g fish. Plasma glucose levels were highly variable in both size classes, and significant increases were only seen at >22° C for the 10 g fish. In contrast, plasma cortisol showed an exponential increase with temperature starting at 16° C in both size classes, and reached maximum levels at 22° C that were 19-fold (10 g fish) and 35-fold (50 g fish) higher than their respective control groups. Both the constitutive (73 kDa) and inducible (72 kDa) isoforms of hsp70 were detected in both size classes using the widely utilized mouse monoclonal antibody. Expression of these isoforms, however, did not change when Atlantic cod were exposed to elevated temperature, and the 72 kDa isoform was not detected using salmonid-specific antibodies. These results indicate that juvenile Atlantic cod are very sensitive to acute increases in water temperature. In addition, they (1) show that M_O2and plasma cortisol, but not plasma glucose or gill hsp 70 levels, are sensitive indicators of thermal stress in Atlantic cod and (2) support previous reports that the upper critical temperature for this species is 16° C.

Chemical and thermal stability of surface‐modified porous polyethylene membranes

In this paper, we describe the surface modification of porous polyethylene by the adsorption of polyelectrolyte mutilayers on plasma‐activated polyethylene surfaces. We use the migration rates of deionized water as an effective alternative to contact angle measurements in order to probe the interfacial energy of the modified surface. The newly acquired surface properties that result from the surface modification are monitored with respect to several key chemical and environmental variables. These variables were chosen so that they will reflect some of the common handling procedures in a laboratory or health care environments, such as exposure to solvents of different pH and polarities, and fluctuations of ambient temperature over an extended period, i.e., “shelf‐life” duration. The stability of these surface properties of the modified membranes is a fundamental requirement for their potential use in a variety of applications involving lateral flow and binding media for bio‐assays. In this paper, we show that a membrane modified by a polyelectrolyte monolayer is more stable than a membrane that has undergone plasma activation alone, while a membrane modified by a polyelectrolyte bilayer exhibits retention of the enhanced surface hydrophilic properties under various conditions and over a long period of time.

Measurement and solutions to thermal comfort, CO2 and ventilation rates in schools

An Australian research facility, conducted a study on several different school classrooms in regards to their thermal comfort, CO2 levels, air temperature stratification and ventilation rates in a selection of Victorian (Melbourne, Australia) schools during a winter season. A brief literature review reveals similar IAQ problems elsewhere (outside Australia) and suggests several HVAC concepts that provide potential solutions. Our intention is to highlight particular IAQ discrepancies in existing school classroom design resulting from these case study measurements, suggesting construction and mechanical operational conditioning improvements.In particular this research confirms the urgency and necessity of addressing IAQ problems in schools, world wide. Our results of the Australian school classroom measurements are similar to other parts of the world, indicating that CO2 levels, ventilation rates and air temperatures are non-compliant with the standards.

Strategies for improving the thermal performance and comfort levels of a kindergarten in the mountains of Nepal

Located on the Annapurna trekking trail in Nepal, Siurung is a remote mountain village where outside influences are almost non-existent. The thermal comfort levels of a recently-constructed kindergarten are well below international standards because of the climate and poor building envelope. A TRNSYS model of the kindergarten has been used to predict the current occupant comfort levels and subsequently determine the most effective way to alter the traditional construction methods to improve comfort levels. Improvements investigated were: reduced air infiltration, roof and wall insulation (separately and together), installation of a smokeless stove and a combination of all strategies.The model predicted that in the current building the PMV ranges from -1.94 in October to - 0.99 in July. It also predicted that the current PPD (%) ranges from 100 in January to 26 in July. With the combination of strategies, the predicted PMV values were all improved to between -1.08 and +0.34, and the PPD values of all months except January were reduced to below 10%. When improving the comfort levels of an existing school, reducing air infiltration, adding roof insulation and installing a smokeless stove are the most effective strategies. When constructing a new school, however, reducing air infiltration and adding insulation to the walls and roof are the most effective and feasible strategies. If a smokeless stove can be afforded and transported to the site, it is recommended that one be installed as it provides a more significant improvement than any other single strategy.

Thermal degradation kinetics and mechanism of epoxidized natural rubber

Thermal resistance is one of the most dominative properties for polymer materials. Thermal degradation mechanisms of epoxidized natural rubber (ENR) and NR are studied by thermogravimetric analysis (TGA) and differential thermal analysis (DTA). The results show that, the introduction of epoxy groups into the NR molecular main chain leads to a remarkable change in the degradation mechanism. The thermal stability of ENR is worse than that of NR. For the first thermooxidative degradation stage, the thermal decomposition mechanism of ENR is similar to that of NR, which corresponds to a mechanism involving one-dimensional diffusion. For the second stage, the thermal decomposition mechanism of ENR is a three-dimensional diffusion, which is more complex than that of NR. Kinetic analysis showed that activation energy (E?), activation entropy (?H) and activation Gibbs energy (?G) values are all positive, indicating that the thermooxidative degradation process of ENR is non-spontaneous.

Towards person authentication by fusing visual and thermal face biometrics

In this chapter we focus on face appearance-based biometrics. The cheap and readily available hardware used to acquire data, their non-invasiveness and the ease of employing them from a distance and without the awareness of the user, are just some of the reasons why these continue to be of great practical interest. However, a number of research challenges remain. Specifically, face biometrics have traditionally focused on images acquired in the visible light spectrum and these are greatly affected by such extrinsic factors such as the illumination, camera angle (or, equivalently, head pose) and occlusion. In practice, the effects of changing pose are usually least problematic and can oftentimes be overcome by acquiring data over a time period, e.g., by tracking a face in a surveillance video. Consequently, image sequence or image set matching has recently gained a lot of attention in the literature [137–139] and is the paradigm adopted in this chapter as well. In other words, we assume that the training image set for each individual contains some variability in pose, but is not obtained in scripted conditions or in controlled illumination. In contrast, illumination is much more difficult to deal with: the illumination setup is in most cases not practical to control and its physics is difficult to accurately model. Thermal spectrum imagery is useful in this regard as it is virtually insensitive to illumination changes, as illustrated in Fig. 6.1. On the other hand, it lacks much of the individual, discriminating facial detail contained in visual images. In this sense, the two modalities can be seen as complementing each other. The key idea behind the system presented in this chapter is that robustness to extreme illumination changes can be achieved by fusing the two. This paradigm will further prove useful when we consider the difficulty of recognition in the presence of occlusion caused by prescription glasses.

Rapid development of non-alcoholic steatohepatitis in Psammomys obesus (Israeli Sand Rat)

Background and AimsA major impediment to establishing new treatments for non-alcoholic steatohepatitis is the lack of suitable animal models that accurately mimic the biochemical and metabolic characteristics of the disease. The aim of this study was to explore a unique polygenic animal model of metabolic disease as a model of non-alcoholic steatohepatitis by determining the effects of 2% dietary cholesterol supplementation on metabolic and liver endpoints in Psammomys obesus (Israeli sand rat).MethodsP. obesus were provided ad libitum access to either a standard rodent diet (20% kcal/fat) or a standard rodent diet supplemented with 2% cholesterol (w/w) for 4 weeks. Histological sections of liver from animals on both diets were examined for key features of non-alcoholic steatohepatitis. The expression levels of key genes involved in hepatic lipid metabolism were measured by real-time PCR.ResultsP. obesus fed a cholesterol-supplemented diet exhibited profound hepatomegaly and steatosis, and higher plasma transaminase levels. Histological analysis identified extensive steatosis, inflammation, hepatocyte injury and fibrosis. Hepatic gene expression profiling revealed decreased expression of genes involved in delivery and uptake of lipids, and fatty acid and triglyceride synthesis, and increased expression of genes involved in very low density lipoprotein cholesterol synthesis, triglyceride and cholesterol export.ConclusionsP. obesus rapidly develop non-alcoholic steatohepatitis when fed a cholesterol-supplemented diet that appears to be histologically and mechanistically similar to patients.

New insight into non-isothermal crystallization of PVA-graphene composites

The melt crystallization of poly(vinyl alcohol) (PVA) and PVA composites has been a controversial subject due to inconclusive evidence and different opinions for its decomposition during crystallization. Using graphene as a model, the melt crystallization of PVA and PVA-graphene composites occurring during single-cycle and multiple-cycle non-isothermal annealing processes was systematically analyzed using different characterization techniques. The results obtained using single-cycle non-isothermal annealing indicated that the entire crystallization process took place through two main stages. The graphene in the PVA matrix regulates the nucleation and crystal growth manner of the PVA, yet resulting in retardation of the entire crystallization. The FTIR and Raman spectroscopic results particularly demonstrated that the annealing process not only improved the crystallinity but also led to clear decomposition in PVA and PVA-graphene composites, such as the elimination of hydroxyl groups and the production of C=C double bonds. The newly produced C=C double bonds were found to be responsible for the retardation of PVA macromolecule crystallization and the breaking of hydrogen bonds among the hydroxyl groups in the PVA chains. In addition, the morphological observation and multi-cycle non-isothermal crystallization further confirmed the existence of decomposition based on the surface damage as well as decreased crystallization enthalpy and crystallization peak temperature. Therefore, the non-isothermal crystallizations of the pure PVA and the PVA-graphene composites were in fact the combination of non-isothermal crystallization and non-isothermal degradation processes.

Investigation of hybrid ion-exchange membranes reinforced with non-woven metal meshes for electro-dialysis applications

Salt and solvent permeations across ion-exchange membranes used in electro-dialysis are directly related to the membrane material structure and chemistry. Although primarily used for aqueous effluents desalination, electro-dialysis was recently shown to be a promising technology for industrial wastewater and co-solvent mixtures purification. The harsh working conditions imposed by these liquid effluents, including high suspended solids, require the development of more chemically and mechanically resistant membranes. In this study, commercial porous stainless steel media filters (240 μm thick) were used as a backbone to prepare hybrid ion-exchange membranes by casting ion-exchange materials within the porous metal structure. The surface of the metal reinforcements was modified by plasma treatment prior to sol-gel silane grafting to improve the interface between the metal and the ion-exchange resins. The morphology of novel hybrid materials and the interface between the metal fibers and the ion-exchange material have been characterized using techniques such as scanning electron microscopy and FTIR mapping. The thickness of the silane coating was found to lie between 1 and 2 μm while water contact angle tests performed on membrane surfaces and corrosion test behaviors revealed the formation of a thin passivating oxide layer on the material surfaces providing anchoring for the silane grafting and adequate surface energy for the proper incorporation of the ion-exchange material. The hybrid membranes desalination performance were then tested in a bench top electro-dialysis cell over a range of flow rate, current densities and salt concentration conditions to evaluate the ability of the novel hybrid materials to desalinate model streams. The performance of the hybrid membranes were benchmarked and critically compared against commercially available membranes (Selemion™). Although the salt transfer kinetics across the hybrid ion-exchange composite membranes were shown to be comparable to that of the commercial membranes, the low porosity of the stainless steel reinforcements, around 60%, was shown to impede absolute salt permeations. The hybrid ion-exchange membranes were however found to be competitive at low current density and low flow velocity desalination conditions.

Investigation of hybrid ion-exchange membranes reinforced with non-woven metal meshes for electro-dialysis applications

Salt and solvent permeations across ion-exchange membranes used in electro-dialysis are directly related to the membrane material structure and chemistry. Although primarily used for aqueous effluents desalination, electro-dialysis was recently shown to be a promising technology for industrial wastewater and co-solvent mixtures purification. The harsh working conditions imposed by these liquid effluents, including high suspended solids, require the development of more chemically and mechanically resistant membranes. In this study, commercial porous stainless steel media filters (240. μm thick) were used as a backbone to prepare hybrid ion-exchange membranes by casting ion-exchange materials within the porous metal structure. The surface of the metal reinforcements was modified by plasma treatment prior to sol-gel silane grafting to improve the interface between the metal and the ion-exchange resins. The morphology of novel hybrid materials and the interface between the metal fibers and the ion-exchange material have been characterized using techniques such as scanning electron microscopy and FTIR mapping. The thickness of the silane coating was found to lie between 1 and 2. μm while water contact angle tests performed on membrane surfaces and corrosion test behaviors revealed the formation of a thin passivating oxide layer on the material surfaces providing anchoring for the silane grafting and adequate surface energy for the proper incorporation of the ion-exchange material. The hybrid membranes desalination performance were then tested in a bench top electro-dialysis cell over a range of flow rate, current densities and salt concentration conditions to evaluate the ability of the novel hybrid materials to desalinate model streams. The performance of the hybrid membranes were benchmarked and critically compared against commercially available membranes (Selemion™). Although the salt transfer kinetics across the hybrid ion-exchange composite membranes were shown to be comparable to that of the commercial membranes, the low porosity of the stainless steel reinforcements, around 60%, was shown to impede absolute salt permeations. The hybrid ion-exchange membranes were however found to be competitive at low current density and low flow velocity desalination conditions.

Milled non-mulberry silk fibroin microparticles as biomaterial for biomedical applications

Silk fibroin has been widely employed in various forms as biomaterials for biomedical applications due to its superb biocompatibility and tunable degradation and mechanical properties. Herein, silk fibroin microparticles of non-mulberry silkworm species (Antheraea assamensis, Antheraea mylitta and Philosamia ricini) were fabricated via a top-down approach using a combination of wet-milling and spray drying techniques. Microparticles of mulberry silkworm (Bombyx mori) were also utilized for comparative studies. The fabricated microparticles were physico-chemically characterized for size, stability, morphology, chemical composition and thermal properties. The silk fibroin microparticles of all species were porous (∼5μm in size) and showed nearly spherical morphology with rough surface as revealed from dynamic light scattering and microscopic studies. Non-mulberry silk microparticles maintained the typical silk-II structure with β-sheet secondary conformation with higher thermal stability. Additionally, non-mulberry silk fibroin microparticles supported enhanced cell adhesion, spreading and viability of mouse fibroblasts than mulberry silk fibroin microparticles (p<0.001) as evidenced from fluorescence microscopy and cytotoxicity studies. Furthermore, in vitro drug release from the microparticles showed a significantly sustained release over 3 weeks. Taken together, this study demonstrates promising attributes of non-mulberry silk fibroin microparticles as a potential drug delivery vehicle/micro carrier for diverse biomedical applications.

Enhanced thermal stability and lifetime of epoxy nanocomposites using covalently functionalized clay: Experimental and modelling

The present work aims at finding a relationship between kinetic models of thermal degradation process with the physiochemical structure of epoxy-clay nanocomposites in order to understand its service temperature. In this work, two different types of modified clays, including clay modified with (3-aminopropyl)triethoxysilane (APTES) and a commercial organoclay, were covalently and non-covalently incorporated into epoxy matrix, respectively. The effect of different concentrations of silanized clay on thermal behaviour of epoxy nanocomposites were first investigated in order to choose the optimum clay concentration. Afterwards, thermal characteristics of the degradation process of epoxy nanocomposites were obtained by TGA analysis and the results were employed to determine the kinetic parameters using model-free isoconversional and model-fitting methods. The obtained kinetic parameters were used to model the entire degradation process. The results showed that the incorporation of the different modified clay into epoxy matrix change the mathematical model of the degradation process, associating with different orientations of clay into epoxy matrix confirming by XRD results. The obtained models for each epoxy nanocomposite systems were used to investigate the dependence of degradation rate and degradation time on temperature and conversion degree. Our results provide an explanation as to how the life time of epoxy and its nanocomposites change in a wide range of operating temperatures as a result of their structural changes.

Effects of stress on reproduction in non-rodent mammals : the role of glucocorticoids and sex differences

The means by which stress influences reproduction is not clearly understood, but may involve a number of endocrine, paracrine and neural systems. Stress impacts on the reproductive axis at the hypothalamus (to affect GnRH secretion) and the pituitary gland (to affect gonadotrophin secretion), with direct effects on the gonads being of less importance. Different stressors have different effects and there are differences in response to short- and long-term stress. Many short-term stresses fail to affect reproduction and there are reports of stimulatory effects of some 'stressors'. There are species differences in the way that specific stressors affect reproduction. Sex differences in the effects of a particular stressor have been delineated and these may relate to effects of stress at different levels of the hypothalamo-pituitary axis. The significance of stress-induced secretion of cortisol varies with species. In some instances, there appears to be little impact of short-term increases in cortisol concentrations and protracted increases in plasma concentration seem to be required before any deleterious effect on reproduction is apparent. Issues of sex, sex steroid status, type of stressor and duration of stress need to be considered to improve understanding of this issue.

Simultaneous crystallization and decomposition of PVA/MMT composites during non-isothermal process

Decomposition of poly(vinyl alcohol)/montmorillonite clay (PVA/MMT) composites during melting-crystallization was experimentally confirmed by morphology and molecular structure changes. In particular, FTIR spectra show the shift of O-H stretching band as well as enhanced intensities of C-O stretching and CH2 rocking vibrational modes. Furthermore, Raman deconvolution indicates that C-H wagging, CH2-CH wagging, CH-CO bending and CH2 wagging modes in amorphous domains were all decreased greatly. Moreover, this decomposition leads to decreased melting enthalpy, melting point, crystallization enthalpy and crystallization temperature. Crystallization analysis shows that the MMT incorporated slows down the crystallization process in the PVA matrix regardless of the nucleation capability of MMT. Despite the severe decomposition, the crystallization kinetics still corroborated well with common classical models. As a result, molecular structure changes and crystallization retardation observed in this study clearly indicate the strong effects of the thermal degradation on the non-isothermal crystallization of PVA/MMT composites.

The effect of marine and non-marine phospholipid rich oils when fed to juvenile barramundi (Lates calcarifer)

An experiment was conducted to assess the response of juvenile barramundi (Lates calcarifer) to four diets containing either marine- or non-marine derived neutral lipid (NL) or polar lipid (PL) sources for eight weeks in a 2 × 2 factorial design. The four diets contained 8.2% added lipid composed of a 1% fish oil base with 7.2% test lipid (n - 3 NL: Fish oil, n - 3 PL: Krill oil, n - 6 NL: Soybean oil, n - 6 PL: Soybean lecithin). The results demonstrated that the different lipid sources (either n - 3 or n - 6 omega series from either NL or PL class) had significant effects on growth performance and feed utilisation with some interaction terms noted. Growth was negatively affected in the n - 6 NL fish and the feed conversion (FCR) was highest in the n - 6 PL fish. Digestibility of total lipid and some specific fatty acids (notably 18:2n - 6 and 18:3n - 3) were also negatively affected in the n - 6 PL fish. Analysis of the whole body neutral lipid fatty acid composition showed that these mirrored those of the diets and significant interaction terms were noted. However, the whole body polar lipid fatty acids appeared to be more tightly regulated in comparison. The blood plasma biochemistry and hepatic transcription of several fatty acid metabolism genes in the n - 6 PL fed and to a lesser extent in the n - 6 NL fed fish demonstrated a pattern consistent with modified metabolic function. These results support that there are potential advantages in using phospholipid-rich oils however there are clear differences in terms of their origin. Statement of relevance: Juvenile barramundi may benefit from dietary phospholipid.