E12 technique: Conventional epoxy resin sheet plastination

Epoxy plastination techniques were developed to obtain thin transparent body slices with high anatomical detail. This is facilitated because the plastinated tissue is transparent and the topography of the anatomical structures well preserved. For this reason, thin epoxy slices are currently used for research purposes in both macroscopic and microscopic studies. The protocol for the conventional epoxy technique (E12) follows the main steps of plastination—specimen preparation, dehydration, impregnation and curing/casting. Preparation begins with selection of the specimen, followed by freezing and slicing. Either fresh or fixed (embalmed) tissue is suitable for epoxy plastination, while slice thickness is kept between 1.5 and 3 mm. Impregnation mixture is made of epoxy E12 resin plus E1 hardener (100 ppw; 28 ppw). This mixture is reactive and temperature sensitive, and for this reason, total impregnation time under vacuum at room laboratory temperature should not last for more than 20–24 hr. Casting of impregnated slices is done in either flat chambers or by the so‐called sandwich method in either fresh mixture or the one used for impregnation. Curing is completed at 40°C to allow a complete polymerization of the epoxy‐mixture. After curing, slices can be photographed, scanned or used for anatomical study under screen negatoscope, magnification glass or fluorescent microscope. Based on epoxy sheet plastination, many anatomical papers have recent observations of and/or clarification of anatomical concepts in different areas of medical expertice.     

Effects on chick performance and nutrient digestibility of an endo‐xylanase added to a wheat‐ and rye‐based diet in relation to fat source

1. A study with growing chicks investigated the effects of an inclusion of an endo‐xylanase preparation (LYXASAN®) to a wheat‐ and rye‐based diet on performance and nutrient digestibility in relation to the fat source.

2. The basal diet contained 500 g wheat and 100 g rye/kg of diet. The basal diet was supplemented with either 65 g soya oil/kg or 60 g blended animal fat and 5 g soya oil/kg.

3. Endo‐xylanase added to the soya oil diet did not affect weight gain, but there was a numerical improvement in food conversion efficiency which was not statistically significant. When the endo‐xylanase preparation was added to the blended animal fat diet, both weight gain and food utilisation were improved by 9.5% and 6.0%, respectively (P< 0.05).

4. Digestibilities of organic matter, crude fat, crude fibre and NFE were not significantly affected by adding endo‐xylanase to the soya oil diet. However, when endo‐xylanase was included in the blended animal fat diet, digestibility of organic matter, crude fat, crude fibre and NFE were improved (P<0–05). The improvement in fat digestibility was the most pronounced, amounting to 9–4%. Nitrogen retention and metabolisable energy content were improved significantly by the addition of an endo‐xylanase to the animal fat diet (P< 0.05), by 6.6% and 6.5% respectively.

5. From the results of this study, it can be concluded that the effects on chick performance and nutrient digestibility of a dietary endo‐xylanase in a wheat‐ and rye‐based diet are influenced to a considerable degree by the type of fat in the diet.     

Horizontal transmission of Mycobacterium avium subsp. paratuberculosis in cattle in an experimental setting: calves can transmit the infection to other calves

In September 2001, two subsequent transmission experiments both lasting 3 months were carried out to study cow-calf transmission of Mycobacterium avium subsp. paratuberculosis (Map) (Period 1), followed by calf-calf transmission of the infection (Period 2). Every 2 weeks, serum, heparinised blood and faecal samples were collected from all animals. After these experiments, the 20 calves were housed individually for more than 3 years to be able to detect the infection status and excretion pattern of each animal. In autumn 2004, the animals were inseminated, to observe a possible increase in faecal excretion of Map shortly before expected calving. One month before the expected calving date in 2005, animals were slaughtered and several tissues per cow and unborn calf were sampled for culture. The results indicate that horizontal cow-calf transmission is readily achieved (Period 1). At the highest infection pressure (six shedding cows of which three high shedders in Period 1) all five calves excreted Map in their faeces during Period 1 (shortly after infection), and four of these calves during Period 2 (when the shedding cows were absent). After that, excretion became less frequently. Horizontal calf-calf transmission did take place (Period 2), as the four donor-calves infected two receiver-calves. Transmission rates during the 3 months periods were quantified as a reproduction ratio R. The R [95% CI] of cow-calf and calf-calf transmission were estimated as 2.7 [1.1, 6.6] and 0.9 [0.1, 3.2] new infections per infectious animal during 3 months.     

Preparation of Epoxy Shape Memory Polymers for Deployable Space Structures Using Flexible Diamines

In order to develop epoxy shape memory polymers (ESMPs) with high switching temperature and excellent toughness for deployable space structures, the crosslink density and chain flexibility of candidate ESMP samples were tunned by adding two flexible poly(oxypropylene) diamines, Jeffamine D-230 (D230) and Jeffamine D-400 (D400), as a secondary curing agent. The desired switching temperature of ESMPs for deployable space structures was set within the range of 120-135°C. By adding D230 and D400, the switching temperature of the ESMPs could be adjusted to within this range by increasing their crosslink density, and their impact strength could be significantly increased due to the stress relaxation properties of the diamines’ flexible molecular chains. The modulus and tensile strength of the ESMPs increased, but elongation at break decreased, in proportion to the diamine content. The ESMPs with a suitable switching temperature for deployable space structures had a high elongation at break greater than 22 % and good shape recovery and shape fixity ratios. The larger the value of shape recovery ratio, the faster the shape recovery speed.     

An Evaluation of two <Emphasis Type="Italic">H1</Emphasis>-Linked Markers and their Suitability for Selecting <Emphasis Type="Italic">Globodera rostochiensis</Emphasis> Resistant Potatoes in the New York Breeding Program

The golden cyst nematode (Globodera rostochiensis) is a serious pest that can dramatically reduce potato crop yield. Pathotype Ro1 of G. rostochiensis was first detected in the United States in 1941 and is still present on several farms in New York State. The H1 gene confers high levels of resistance to pathotype Ro1 but screening for it with a bioassay is time consuming and expensive. In this study two known molecular markers, 57R and TG689, were evaluated for their ability to identify resistant clones among 38 global cultivars and 350 New York breeding clones. The ability of either marker to predict resistance was high – 99.7% and 98.3% for 57R and TG689, respectively – but the ability to predict susceptibility was much lower, 47% and 41%, respectively. As resistance is the trait of interest, either of these markers is sufficient to make selection decisions in a practical breeding program. Cases exhibiting discordance between presence/absence of diagnostic markers and bioassay results were investigated further. Recombination, inflow of other resistance genes, and occasional failure of marker- and/or bio-assays are discussed as potential causes.     

Transcrytalline structures and crystallization kinetics of Polyarylate/Nylon6 Islands-in-a-Sea conjugate fibers for high performance thermoplastic composite applications

We report the isothermal and non-isothermal crystallization kinetics and associated transcrystalline morphological features of polyarylate(PAR)/nylon6 islands-in-a-sea fibers, where 74 PAR islands serve as reinforcing fibers and nylon6 sea component acts as a semicrystalline matrix in final thermoplastic composites. The temperature-dependent polarized optical microscopic images obtained during a cooling process exhibit that the melt-crystallization is dominated by the interfacial crystallization of nylon6 on the surface of PAR fibers, leading to developing a transcrystalline structure. From the isothermal and non-isothermal melt-crystallization analyses of the islands-in-a sea fiber by using differential scanning calorimetry and the Avrami equation, the overall crystallization rates of the nylon6 sea component in the islands-in-a-sea fiber are found to be highly accelerated by the heterogeneous nucleating effect of the PAR island fibers. In addition, it is revealed that the isothermal and non-isothermal melt-crystallization kinetics of the nylon6 in the islands-in-a-sea fibers consists of two different mechanisms of the primary crystallization owing to the interfacial crystallization and the secondary crystallization due to the bulk crystallization.