Thermodynamics of calcite growth: baseline for understanding biomineral formation

The complexity of biomineralized structures suggests the potential of organic constituents for controlling energetic factors during crystal synthesis. Atomic force microscopy was used to investigate the thermodynamic controls on carbonate growth and to measure the dependence of step speed on step length and the dependence of critical step length on supersaturation in precisely controlled solutions. These data were used to test the classic Gibbs-Thomson relationship and provided the step edge free energies and free energy barriers to one-dimension nucleation for calcite. Addition of aspartic acid, a common component in biomineralizing systems, dramatically affected growth morphology and altered the magnitude of the surface energy.     

Heat Shock Protein 70 and Sex Steroid Receptors in the Follicular Structures of Induced Ovarian Cysts

The purpose of this study was to estimate the expression and relative amounts of estrogen (ER) and progesterone receptors (PR) and their isoforms as well as heat shock protein 70 (HSP70) in ovaries of rats with induced cystic ovarian disease (COD). Primary, secondary, tertiary, atretic and cystic follicles were evaluated by immunohistochemistry and total ovarian proteins were analyzed by Western blot. In the granulosa layer, growing and cystic follicles in the treated group have a higher expression of ERα than growing follicles of control individuals. In the theca interna layer, tertiary follicles presented a significantly higher expression of ERα in the treated group. An increase in total ERα protein was detected in the treated group. Granulosa cells of all growing, atretic and cystic follicles show a lower expression of ERβ in animals with COD, and the total protein expression of ERβ was lower in this group. The expression of PR was lower in the granulosa cell layer of tertiary and cystic follicles in treated animals, and theca interna layer had less intense immunostaining in this group. Although there were no differences in the expression of PR-B by Western blotting, the expression of PR-A was higher and the expression of PR-C was smaller in the treated group. An intense HSP70 immunostaining was observed in the cells of cystic follicles. By Western blotting, higher protein expression of HSP70 was detected in the ovarian samples of the control group than those of the treated ones. Ovaries of animals with COD exhibited an altered steroid receptor expression and subtype balance as compared with control animals, and an increase in HSP70 immunoexpression.     

Effects of carbon nanotubes on morphological structure, thermal and flammability properties of electrospun composite fibers consisting of lauric acid and polyamide 6 as thermal energy storage materials

The ultrafine composite fibers consisting of lauric acid (LA) and polyamide 6 (PA6) as form-stable phase change materials (PCMs), were prepared successfully by electrospinning. The effect of carbon nanotubes (CNTs) on the structural morphology, phase change behaviors, thermal stability, flammability and thermal conductivity properties of electrospun LA/PA6 composite fibers was investigated by field-emission scanning electron microscopy (FE-SEM), differential scanning calorimetry (DSC), thermogravimetric analyses (TGA), microscale combustion calorimeter (MCC) and melting/freezing times measurements, respectively. SEM observations indicated that the LA/PA6 and LA/PA6/CNTs composite fibers possessed flat and ribbon-shaped morphologies, but the neat PA6 fibers had cylindrical shape with smooth surface; and the average fiber diameters for LA/PA6 composite fibers decreased generally with the addition of CNTs. DSC measurements indicated that the heat enthalpies of the composite fibers were lower that that of neat LA powders, while the amounts of CNTs had no appreciable effect on the phase change temperatures and heat enthalpies of the composite fibers. TGA results showed that the addition of CNTs increased the onset thermal degradation temperature, maximum weight loss temperature and charred residue at 700 °C of the composite fibers, attributed to the improved thermal stability properties. It could be found from MCC tests that there were two-step combustion processes for composite fibers, and corresponded respectively to combustion of LA and polymer chains (PA6) in composite fibers. The addition of CNTs reduced the peak of heat release rate (PHRR) of electrospun composite fibers, contributing to the decreased flammability properties. The improved thermal conductivity performances of LA/PA6/CNTs composite fibers was also confirmed by comparing the melting/freezing times of LA/PA6 composite fibers with that of neat LA powders. The results from the SEM observation showed that the composite fibers had no appreciable variations in shape and diameter after heating/cooling processes.     

Aquaculture and international trade

Abstract

In contrast to the stabilization or decline of wild fishery harvests, aquaculture's contribution to the world fish supply is steadily increasing. Aquaculture has begun to have a major influence on the trade of export‐orientated species such as salmon and shrimp. This paper reviews the role of aquaculture in international trade and the research which has been conducted to examine its influence. Despite the growing significance of aquaculture on international trade, especially for shrimp and salmon, formal analysis of the shrimp trade is sparse, only moderate for salmon, and essentially nonexistent for other species. This paper also presents specific examples of how aquaculture has played an important role in international trade. These include an examination of: (1) the influence of shrimp aquaculture and trade on the development of a shrimp futures contract; and (2) the countervailing duty and antidumping case against the Norwegian farmed salmon industry.     

Evidence of multiple divergent mitochondrial lineages within the southern African diplopod genus Bicoxidens Attems, 1928 (Spirostreptida)

Two recent studies have suggested that divergent mitochondrial lineages may be present within spirostreptid genera such as Bicoxidens Attems, 1928. Bicoxidens, similar to many other endemic soil invertebrates, exhibits low dispersal capabilities and strict microclimate habitat preferences, attributes that often lead to geographic isolation. Given that prolonged geographic isolation often lays the foundation for population genetic differentiation, genetic divergence and possibly speciation, there was good reason to suspect that Bicoxidens may consist of several distinct lineages. On this basis, the mitochondrial cytochrome c oxidase subunit 1 (COI) was used to reconstruct the phylogeny of Bicoxidens and reveal divergent lineages within the genus. Maximum likelihood and Bayesian inference analyses recovered a paraphyletic Bicoxidens phylogram with divergent lineages present in three species – B. friendi, B. flavicollis and B. brincki – suggesting high genetic diversity within the genus. Bayesian genetic cluster analyses suggested the presence of multiple distinct mitochondrial lineages within the genus with four identified in B. flavicollis alone. It was therefore concluded that the divergent lineages observed among Bicoxidens populations may suggest the presence of hidden species.     

A specific gravity calculator

A low cost, pocket size, specific gravity calculator has been developed that will convert weight in air and weight in water values directly to specific gravity. This calculator is eminently suitable for use in the field and has been developed for use by potato growers in a research project involving specific gravity determinations of developing tubers.     

家禽饲料中的硒强化效果测定

小麦吸收稀亚硒酸钠溶液发芽，使硒有机化。待芽长至１ｃｍ后，干燥。用动力学光度法分别测定小麦强化前后的含硒量。结果表明，强化后麦芽的含硒量有大幅度提高。再加上小麦胚芽中较高含量的维生素Ｅ，使强化后的麦芽成为理想的家禽饲料。以硒强化饲料及对照日粮分别喂养Ｂ、Ｃ两组母鸡。１５ｄ后，取Ｂ、Ｃ两组的鸡蛋作含硒量测定。结果是Ｂ组鸡蛋含硒量为Ｃ组的１１．８倍，可见，在饲料中提高有机硒含量，十分有利于家禽对硒的吸收。     

Passive infrared camera measurements demonstrate modest effect of mechanically induced internal voids on Dracaena fragrans stem temperature

The use of infrared cameras as a tree diagnostic device was proposed on the basis that internal defects reduce thermal conductivity and surface temperatures, but existing research has failed to demonstrate a clear connection between these two features. Consequently, two experiments were designed to evaluate the effect of internal voids on stem surface temperature. Cylindrical voids were created in 5 cm diameter stems of Dracaena fragrans by mechanically removing internal tissue. In each experiment, the dimension of internal voids varied among five experimental treatments with two controls. Infrared (IR) images were collected by directly focusing the camera on the stem surfaces concealing internal voids. Infrared images were analyzed using a concurrent mixed methods approach, including qualitative image evaluation and quantitative surface temperature analysis. In each experiment, IR image evaluation revealed a noticeable reduction in surface temperature around the largest void size (3.8 cm). Analyses of linear temperature trending and surface temperature mostly corroborated the visual evaluation. The average temperature above the largest void size was 0.4–0.6 °C lower than other treatments, which remained substantially similar to one another. Overall, these results suggest the technique is exclusively able to identify relatively large internal defects occupying at least 76% of the stem cross-sectional area.