Detailed morphological analysis of axolotl sperm

The axolotl has extraordinary regeneration capacity compared to other vertebrates. This remarkable potential has been attributed to its life-long neoteny, characterized by the exhibition of embryonic characteristics at the adult stage. A recent study provided a detailed morphological analysis of the sperm morphology of the Ambystoma mexicanum using routine and detailed histological techniques. The primary purpose of the present study is to describe a simple and inexpensive method for evaluating the morphology of axolotl sperm. In this study, spermatophore structures were collected and spread on slides and air-dried. The slides were stained with periodic acid Schiff, toluidine blue, Masson’s trichrome, Giemsa, Spermac, and Diff-Quik dye for a morphological examination. The slides were coated with gold/palladium for a scanning electron microscopy examination. The sperm of the axolotl consisted of an elongated head, a neck, and a flagellum covered with an undulating membrane. The lengths of the midpiece, tail, and head were 8.575 µm, 356.544 µm, and 103.661 µm, respectively. In the flagellum part, the wavy membrane structure, whose function has not been explained, surrounds the tail. The data obtained from this study will constitute an important step in designing future research on the reproductive and regeneration capacity of the axolotl.

Study on Microstructure and Properties of 12Ag–Cu–Zn–Sn Cadmium-Free Filler Metals with Trace in Addition

The effect of different In contents on the melting characteristics, mechanical properties, and microstructure of 12Ag–Cu–Zn–Sn filler metal was investigated in this paper, and flame brazing of 304 stainless steel and copper plates was done using the 12Ag–Cu–Zn–Sn–xIn filler metal. The results indicate that adding appropriate amount of In can evidently decrease the solidus and liquidus temperatures and improve the wettability of the low silver based filler metals. In addition, the shear strength of 304 stainless steel and copper plates joint brazed by 12Ag–Cu–Zn–Sn–1In are satisfactory due to the solution strength effect, and scanning electron microscopy examination of the braze-zone revealed that more relatively sound joints were obtained when brazing was done with 12Ag–Cu–Zn–Sn–xIn filler metal than with Indium free one; its performance is comparable to that of the joint brazed with the 20Ag–Cu–Zn–Sn filler metal, having a remarkable silver-saving effect.

Revision of the genus Setosella (Bryozoa: Cheilostomata) with description of new species from deep-waters and submarine caves of the Mediterranean Sea

The genus Setosella included to date six species. After revision, only four of these species were retained, i.e. S. vulnerata, S. cavernicola, S. folini and S. spiralis. The remaining two species were tentatively placed in Woodipora, W.? antilleana n. comb., and Andreella, A.? fragilis n. comb. On the other hand, scanning electron microscopy examination of Mediterranean material, revealed the presence of three new species previously included in species complexes: S. cyclopensis n. sp. from the open-shelf, S. rossanae n. sp. from submarine caves, and S. alfioi n. sp. from deep-waters. The diagnosis of the genus was amended to include the occurrence of kenozooids in S. cyclopensis n. sp. and S. cavernicola, and of free-living ring-shaped and scorpioid colonies in S. folini and S. alfioi n. sp. All the seven species n 1ow in Setosella have present-day representatives; the geographic distribution of the genus 1sinian of southern Italy and insular Greece, with only three species occasionally and discontinuously reported. All species are able to produce numerous, subsequent intramural buds and morphological differences seem to be consistently associated with exploitation of particular habitats and substrata.

WEAR MECHANISM OF TICN AND TIALN COATED DRILL IN DRILLING OF CARBON STEEL

TiCN and TiAlN coated twist drills were subjected to drilling tests to investigate the failure mechanisms during drilling operation. The drilling tests were performed on a carbon steel plate with a thickness of 25 mm and the depth of drill was set at 20 mm. The drill performance parameters were set at a spindle rotation of 1,600 rpm and feed rate of 20 mm/min. Each sample was then subjected to Scanning Electron Microscopy examination to investigate the wear mechanisms operated during drilling. Microstructural examination showed that the abrasion, adhesion and thermal wear mechanisms are operated during drilling process.

Spark Plasma Sintered WC-Ni Cemented Carbides with Various Contents of ZrC Nano-Powder

WC-10Ni cemented carbides with various contents (0-9 wt.%) of ZrC nanopowder were fabricated by spark plasma sintering at 1350 °C with a pressure of 50 MPa. The phase composition, microstructure and mechanical properties of the as-prepared samples were investigated. X-ray diffraction analysis revealed that excepting WC hard phase, a solid solution phase Ni (W,Zr) with different amounts of individual metal was formed with increasing ZrC nanopowder content. Scanning electron microscopy examination indicated that a proper addition content of ZrC can suppress the abnormal growth of WC grains and improve the relative density of WC-Ni cemented carbides. However, with further increase in the content of ZrC (more than 7 wt.%), the agglomeration of ZrC became more and more serious. The samples with 5 wt.% ZrC nanopowder possess a relative higher flexural strength (~1750 MPa) among all the investigated samples. When the addition content of ZrC nanopowder was 3 wt.%, the Vickers hardness of the samples reached its maximum value (~1810 HV10).