Induction and prepatterning of the zebrafish pectoral fin bud requires axial retinoic acid signaling

Vertebrate forelimbs arise as bilateral appendages from the lateral plate mesoderm (LPM). Mutants in aldh1a2 (raldh2), an embryonically expressed gene encoding a retinoic acid (RA)-synthesizing enzyme, have been used to show that limb development and patterning of the limb bud are crucially dependent on RA signaling. However, the timing and cellular origin of RA signaling in these processes have remained poorly resolved. We have used genetics and chemical modulators of RA signaling to resolve these issues in the zebrafish. By rescuing pectoral fin induction in the aldh1a2/neckless mutant with exogenous RA and by blocking RA signaling in wild-type embryos, we find that RA acts as a permissive signal that is required during the six- to eight-somite stages for pectoral fin induction. Cell-transplantation experiments show that RA production is not only crucially required from flanking somites, but is sufficient to permit fin bud initiation when the trunk mesoderm is genetically ablated. Under the latter condition, intermediate mesoderm alone cannot induce the pectoral fin field in the LPM. We further show that induction of the fin field is directly followed by a continued requirement for somite-derived RA signaling to establish a prepattern of anteroposterior fates in the condensing fin mesenchyme. This process is mediated by the maintained expression of the transcription factor hand2, through which the fin field is continuously posteriorized, and lasts up to several hours prior to limb-budding. Thus, RA signaling from flanking somites plays a dual early role in the condensing limb bud mesenchyme.

Photocatalytic decolorization of lanasol blue CE dye solution using a flat-plate reactor

This paper reports the effectiveness of the photocatalysis TiO₂ in degrading Lanasol Blue CE. A flat-plate reactor (FPR) with a reactor area of 0.37 m² and ultraviolet (UV) light source of six 36 W blacklight lamps was used in the study. Operating variables including dosage of the photocatalyst, flow rates through the FPR, UV intensity, and tilted angle of the reactor were investigated to degrade Lanasol Blue CE. Results showed that the photocatalytic process can efficiently remove the color in textile dyeing effluent. The degradation process was approximated using first-order kinetics. The photocatalytic apparent reaction rate increased with the increasing UV intensity received by the photocatalyst TiO₂ in slurry. The liquid flow rate and tilted angle influenced the film thickness. The apparent reaction rate constant was mainly determined by the liquid film thickness, UV intensity, and the dosage of the photocatalyst. The findings of this research can be utilized as preliminary input for potential solar photocatalytic applications on color removal from dye solutions.

Surface bands on deepwater squalid dorsal-fin spines : an alternative method for ageing centroselachus crepidater

Bands on the external surface of the second dorsal-fin spine proved to be a novel method of estimating the age and growth of Centroselachus crepidater. Bands that followed the shape of the spine base were enhanced with an alizarin red derivative. Internal bands in spine cross sections were also examined. The number of both external and internal bands increased with animal size, although most spines had more external than internal bands. External bands were more reliable and were assumed to be annuli. The rate of band formation differed after five bands had been formed, and internal bands ceased forming after 30 years. Females to 54 years old and males to 34 years old were examined. Maturity occurred over a wide age range, with estimates of 20 years for females and 9 years for males. The youngest pregnant female was 27 years old. The Francis reparameterized von Bertalanffy growth model found similar growth for males and females, and the von Bertalanffy equations were L _t = 96.12^{(1 – e(–0.072(t+6.13))}) for females and L_t = 73.22(1 – e^{(–0.141(t+2.99))}) for males.

Photocatalytic degradation of dyes in wastewater using TiO2/UV in a flat-plate reactor

The photocatalyst TiO₂ with UV irradiation was used to degrade dyes in textile effluent in a flat-plate photoreactor. A test system was built with the reactor area of 1 x 0.3m2, UV light of six 36W-blacklight. TiO₂ powder P25 with BET surface area 50±15m2/g, average primary particle size 21 nm, purity> 99.5% and content of 83.9% anatase and 16.1 % rutile was used as the photocatalyst. A number of dyes commonly present in dyeing wastewater were tested in this study. The different operating parameters, such as dosage of photocatalyst, the structure of the reactor, flow rates through the flat-plate reactor, UV radiation intensity and tilted angle of the reactor, were investigated. The results showed that the photocatalytic process could efficiently remove most of the colour contained in the dyeing wastewater. It was experimentally observed that first-order kinetics was adequate for characterising the process. The flow rate and the tilted angle had some influence on the film thickness of the fluid in the reactor and the empirical correlation between the film thickness of the fluid and these two parameters was developed. The photoreaction rate was mainly determined by the film thickness of the fluid on the reactor surface and the dosage of the photocatalyst. Optimum operating parameters of the system were found to be at the film thickness of about 1.4mm and a TiO₂ dosage of 1 gIL. The higher the UV intensity, the faster the reaction rate was. The results of these experiments showed that this method has the great potential for colour removal from wastewater at commercial scale.

To overcome the common difficulty of separating the used TiO₂ suspension after treatment precipitation followed with filtration was used in this study to determine the separation efficiencies. On the other hand, TiO₂ in a small pillar shape was also studied for photocatalytic degradation of textile dye effluent. The pillar pellet was made in Oegussa Company, Germany ranging from 2.5 to 5.3mm long and with a diameter of 3.7mm. It was almost pure TiO₂ (83.2% anatase and 16.8% rutile), with a S-content of <20 ppm and a CI content of the order of 0.1 wt. %. No further elements are present in contents above 0.05 wt.%. The TiO₂ pillars were placed on the flat-plate reactor that was divided by the rectangular slots and irradiated under UV light when the treated solution went through the reactor. Four dyes and their mixtures were tested. The results showed that the photocatalytic process under this configuration efficiently remove the colour from textile dyeing effluent, and pillar shape TiO₂ photocatalyst was not dissolved in water and very easy to be separated from solution, enabling it to be reused many times. The first-order kinetics was adequate for characterising the photocatalytic degradation process and the photocatalytic performance was comparable to TiO₂ powder. It is believed that the TiO₂ pellet would be a preferable form of photocatalyst in applications for textile effluent treatment process, and other wastewater treatment processes.

A solar collector with the absorber divided by rectangular slots

A new solar absorber structure has been proposed and studied in this paper. The metal tubes running perpendicular to a set of parallel rectangular metal fins make the solar absorber with rectangular slots. Studies on the collector were theoretically carried out in the aspects of heat transfer, thermodynamics and . hydrodynamics. The calculating methods for calculating fin efficiency F and efficiency factors of the collector F' were obtained. The results showed that the new solar collector would have the higher efficiency and better performance at higher fluid temperature than that of the traditional flat-plate collectors. A collector prototype with the new structure was built and tested. The testing results agree with our theoretical results.

Solar photocatalytic oxidation (PCO) process with a flat-plate reactor

An experimental rig with a flat-plate solar reactor was built to study the effectiveness of degradation using the reactive methylene blue as sensitive objective. The factors that affect the degradation performance, such as dosages of photocatalyst (Ti0₂), initial concentration of reactive methylene blue, flow rate through the flat-plate reactor, solar UV radiation intensity and decolourising efficiency of the solution, have been investigated. The results showed that the solar PCO process with a Flat-plate Reactor could degrade the methylene blue and decolour in methylene blue solution efficiently.

A comparative study of microstructures and mechanical properties obtained by bar and plate rolling

Microstructures and mechanical properties of a low carbon steel were studied after plate rolling and bar rolling. Plate rolling is characterized as a monotonic compressive loading, while bar rolling is characterized as a cross-compressive loading. A four-pass plate rolling and bar rolling experiment was designed so that the material experiences the same amount of strain at each pass during rolling. The rolling experiment was performed at moderately high temperatures (450, 550 and 650 °C). The microstructures and mechanical properties of the low carbon steel acquired from the two types of rolling experiments were compared. The results revealed that differences of loading path attributed by monotonic loading (plate rolling) and cross loading (bar rolling) significantly influenced the microstructures and mechanical properties such as yield stress, ultimate tensile stress, strain hardening exponent and elongation of the low carbon steel.

Seasonality of blue and fin whale calls and the influence of sea ice in the Western Antarctic Peninsula

The calling seasonality of blue (Balaenoptera musculus) and fin (B. physalus) whales was assessed using acoustic data recorded on seven autonomous acoustic recording packages (ARPs) deployed from March 2001 to February 2003 in the Western Antarctic Peninsula. Automatic detection and acoustic power analysis methods were used for determining presence and absence of whale calls. Blue whale calls were detected year round, on average 177 days per year, with peak calling in March and April, and a secondary peak in October and November. Lowest calling rates occurred between June and September, and in December. Fin whale calling rates were seasonal with calls detected between February and June (on average 51 days/year), and peak calling in May. Sea ice formed a month later and retreated a month earlier in 2001 than in 2002 over all recording sites. During the entire deployment period, detected calls of both species of whales showed negative correlation with sea ice concentrations at all sites, suggesting an absence of blue and fin whales in areas covered with sea ice. A conservative density estimate of calling whales from the acoustic data yields 0.43 calling blue whales per 1000 n mi² and 1.30 calling fin whales per 1000 n mi², which is about one-third higher than the density of blue whales and approximately equal to the density of fin whales estimated from the visual surveys.

Nutrient intake and plate waste from an Australian residential care facility

Objective: To determine the plate waste, energy and selected-nutrient intake, from elderly residents living in a high-level care (HLC) and low-level care (LLC) facility.

Design: Three, single, whole day assessments of plate waste, energy, and selected nutrients, using a visual rating plate waste scale.

Setting: Long-term residential care establishment.

Subjects: One hundred and sixty-nine (93 HLC and 76 LLC) individual daily intakes.

Main findings: The mean energy wasted throughout the whole day was 17%. The energy wasted from main meals (16%) was significantly less than the energy wasted at mid-meals (22%, P=0.049). The lowest mean energy wastage occurred at breakfast (8%) compared to lunch (22%) and dinner (25%, P<0.001). The mean (s.d.) daily energy served and consumed was 8.1 (2.0) and 6.6 (2.2) MJ, respectively. There was no difference in energy served or consumed between HLC and LLC residents. On the observation day, 60% of residents consumed less than their estimated energy requirement. The mean calcium intake was 796 (346) mg, and the median (inter-quartile range) vitamin D intake was 1.78 (2.05) μg.

Conclusion: On 1 day, more than half the residents surveyed were at risk of consuming an inadequate energy intake, which over-time, may result in body weight loss. Although wastage was not excessive and energy served was adequate, the amount of food eaten was insufficient to meet energy and calcium requirements for a significant number of residents and it is not possible to consume sufficient vitamin D through food sources.

Laminated plate elements based on higher-order shear deformation theories

Efficient and accurate finite elements are crucial for finite element analysis to provide adequate prediction of the structural behavior. A large amount of laminated plate elements have been developed for finite element analysis of laminated composite plates based on the various lamination theories. A recent and complete review of the laminated finite elements based on the higher-order shear deformation theories, including the global higher-order theories, zig-zag theories and the global-local higher-order theories is presented in this paper. Finally some points on the development of the laminated plate elements are summarized.

Process for the production of ultrafine plate-like alumina particles

A process for producing plate-like alumina particles with a high aspect ratio is described. Nano-sized particles of an aluminium precursor compound, optionally formed by milling, are mixed with a sufficient volume fraction of a diluent and heat treated to form substantially discrete plate-like alpha alumina particles dispersed in the diluent. A mineraliser may be added to lower the effective melting point of the system. Substantially discrete plate-like particles may be formed without agitation when the heat treatment is conducted below the melting point of the diluent.

A simple displacement-based quadrilateral laminated composite plate element - part I : linear analysis

Based on the first-order shear deformation theory (FSDT) and Timoshenko's laminated composite beam functions, a simple displacement-based 4-node, 24-dof quadrilateral laminated plate element is proposed in this paper for linear analysis of thin to moderately thick laminates. The deflection and rotation functions of the element boundary are obtained from the Timoshenko's laminated composite beam functions, hence convergence to the thin plate solution can be achieved theoretically and shear-locking problem is avoided naturally. The in-plane displacement functions of a quadrilateral plane element with drilling degrees of freedom are taken as the in-plane displacements of the proposed quadrilateral element. Some numerical examples of linear analysis of composite laminated plates are calculated, and the results show that the proposed element is convergent, shear-locking free, efficient, accurate and not sensitive to mesh distortion.

A simple displacement-based quadrilateral laminated composite plate element : Part II : linear analysis

The 4-node, 24-dof quadrilateral displacement-based element (Zhang et al. 2004), which have been developed successfully for linear analysis of thin to thick laminated composite plates, is extended further for geometrically nonlinear analysis in this paper. The proposed element is based on the first-order shear deformation theory (FSDT) and von-Karman's large deflection theory, and the total Lagrangian approach is employed to formulate the element. The deflection and rotation functions of the element boundary are obtained from Timoshenko's laminated composite beam functions. The developed element is simple in formulation, free from shear-locking, and include conventional engineering degrees of freedom. Numerical examples demonstrate that the element is accurate and efficient for large deformation, small rotation geometrically nonlinear analysis of thin to moderately thick laminated composite plates.