Cross-sectional measurement of grain boundary segregation using WDS.

A new method is proposed for the quantification of grain boundary segregation using Wavelength Dispersive Spectroscopy (WDS) in a Scanning Electron Microscope (SEM). Analyses are undertaken on a simple metallographically polished section of material. The method is demonstrated for the model system of sulphur segregation to nickel grain boundaries. Quantification was carried out from sulphur concentration profiles acquired across 11 grain boundaries of a nickel specimen containing 5.4wtppm of sulphur in the bulk and equilibrated at 550°C. The average sulphur grain boundary concentration determined is µ=35.2ngcm-2=6.6×1014 atoms cm-2≈0.5 monolayer, which is in good agreement with a previous quantification obtained from SIMS (Secondary Ion Mass Spectrometry) on the same material. However this is lower by a factor of two than the quantification obtained using "surface" techniques on fractured specimens of the same material. With the conditions of analysis used in this study, the limit of detection of the method developed is found to be better than 10% of a sulphur monolayer.

Oolemma rupture inside the intracytoplasmic sperm injection needle significantly improves the fertilization rate and reduces oocyte damage.

OBJECTIVE: To compare the effect on fertilization, oocyte damage, embryo freezing, and pregnancy rates of two different techniques for rupturing the oolemma during intracytoplasmic sperm injection (ICSI). DESIGN: Retrospective study. SETTING: Fertility Center, Alliant Health System Hospital. PATIENT(S): Seventy-nine consecutive IVF-ICSI cases. INTERVENTION(S): Patients in group I had ICSI performed by pushing the needle into the oocyte until the oolemma was observed to break outside the needle. In group II the oolemma was aspirated into the needle until it ruptured inside the needle. MAIN OUTCOME MEASURE(S): In group II ICSI resulted in significantly higher fertilization and lower oocyte damage rates (66% and 13%) than in group 1 (39% and 29%). There were no statistically significant differences in embryo cleavage rates or pregnancy rates per retrieval between the two groups. A greater number of cases had embryos cryopreserved in group II than in group I. RESULT(S): Rupturing the oolemma by aspirating it into the ICSI needle (group II) improved laboratory outcomes compared with the more traditional technique of breaking this membrane by the stabbing action of the needle (group I). This modification of the ICSI technique also increased the number of patients with cryopreserved embryos and therefore could increase the pregnancy rate per patient. CONCLUSION(S): The site and technique used to rupture the oolemma during ICSI has a significant effect on the fertilization and damage rates.

Improved clinical outcomes for in vitro fertilization with delay of embryo transfer from 48 to 72 hours after oocyte retrieval: use of glucose- and phosphate-free media.

OBJECTIVE: To evaluate clinical outcomes of day 2 versus day 3 ET using a culture media with no glucose or phosphate. DESIGN: Retrospective clinical study. SETTING: Hospital-based fertility clinic. PATIENT(S): One hundred seventy-six IVF-ET patients undergoing controlled ovarian supraovulation. INTERVENTION(S): IVF and delaying the ET by 1 day. MAIN OUTCOME MEASURE(S): Number of blastomeres per embryo, implantation and pregnancy rates. RESULT(S): Delaying the ET from day 2 to day 3 after oocyte retrieval significantly increased implantation rates (13% versus 24%) and ongoing/delivered pregnancy rates per retrieval (26% versus 44%). Day 3 embryos with > or = 8 blastomeres resulted in a significantly higher pregnancy rate (53%) than day 3 embryos with < 8 cells (23%) and day 2 embryos with > or = 4 cells (31%) or < 4 cells (11%). CONCLUSION(S): Day 3 ET was associated with a significant increase in implantation and pregnancy rates. Delaying the ET until day 3 may permit the selection of more viable embryos than on day 2. The absence of glucose and phosphate from the culture media is compatible with good IVF outcomes.

Quantitative analysis of orb web patterns in four species of spiders.

The orb webs of the four species Araneus pima (species nova), Araneus diadematus (Clerck), Argiope aurantia (Lucas), and Neoscona domiciliorum (Hentz) built under controlled laboratory conditions were compared and evaluated quantitatively at two different points in the life cycle in regard to size, regularity, shape, and fine structure. Orb webs of two species from one genus can be distinguished, but are more alike than webs from different genera. Mature spiders built highly specific webs, a fact which may play a role in species isolation during courtship. In adults, web measures correlated in size with the spiders' taxon; young spiders' web size measurements corresponded rather to their body weight or leg length. A web's regularity seemed to be closely related to age. Adult and young spiders built oval-shaped webs with eccentric hubs. Mesh width was correlated with leg length at both age levels. Web data support the likelihood of a monophyletic evolution of the four species.