Laser annealing effects on the electrical characteristics of SOS transistors

Successful incorporation of laser annealing techniques into standard processing methods requires that the electrical characteristics of the devices not be degraded. In this work, a range of energy densities from pulsed u.v. and visible lasers which can be utilized in silicon on sapphire (SOS) technology to improve device performance without introducing any deleterious side effects is determined experimentally. Silicon islands were photolithographically defined and chemically etched (KOH) on standard SOS wafers which were subsequently exposed to pulsed (25 nsec) ruby ($\text{λ = 6943}\text{A}\text{?}$) and excimer ($\text{λ = 2490}\text{A}\text{?}$) laser radiation. Comparative studies of the effect of front and back side (through the sapphire) irradiation of the silicon on device performance were conducted. Using standard processing techniques, MOS transistors were fabricated after laser irradiation and electrically characterized. It was found that under certain conditions utilization of lasers in SOS processing, can result in an increase in the interface state density at both the top 〈100〉 Si-SiO₂ interface and the bottom Al₂O₃-Si interface. However, a set of conditions exists, in which it is possible to apply laser annealing to standard SOS processing so as to increase MOS/SOS transistor channel mobility by over 30% without causing any degradation of the device electrical characteristics.     

Some practical aspects connected with the presence of calcium in soybean oils

Presence of calcium in crude and degummed soybean oils prevents complete elimination of phosphatides by hydration and enhances the formation of heavy precipitates. They block industrial centrifuges at the later stages of the refining processes. Industrially extracted degummed soybean oils contain appreciable amounts of calcium (ca. 100 ppm) and its source was traced to the processed soybeans. Various pre-extraction treatments of the soybeans in industry augment the calcium content in the oils, since crude Soxhlet-extracted soybean oils contained only 15 ppm calcium. Additions at the alkali-refining stages of EDTA or of polyphosphate, to stabilize aqueous suspensions which also contain calcium salts, are suggested as a partial remedy to the frequent blocking of the centrifuges.     

Absorption and distribution of orally administered jojoba wax in mice

The liquid wax obtained from the seeds of the arid-land shrub jojoba (Simmondsia chinensis) is finding increasing use in skin treatment preparations. The fate of this wax upon reaching the digestive tract was studied.¹⁴C-Labeled wax was administered intragastrically to mice, and the distribution of the label in the body was determined as a function of time. Most of the wax was excreted, but a small amount was absorbed, as was indicated by the distribution of label in the internal organs and the epididymal fat. The label was incorporated into the body lipids and was found to diminish with time.Lipids 17: 169–171. 1982.     

Advanced IEEE 802.11ax TCP aware scheduling under unreliable channels

In this paper, we suggest advanced IEEE 802.11ax (WiFi) TCP‐aware scheduling strategies for optimizing the TCP Goodput AP operation under transmission of unidirectional TCP traffic to downloading stations. Our scheduling strategies optimize the TCP Goodput performance using the capability for Multi User transmissions over the Uplink, first introduced in IEEE 802.11ax, together with Multi User transmissions over the Downlink. The scheduling strategies are based on Transmission Opportunities (TXOP), and we suggest three scheduling strategies determining the TXOP formation parameters. In one of the strategies, one can control the achieved TCP Goodput vs the delay. We also assume saturated TCP transmission queues. We show that with minimal TCP Goodput degradation, one can avoid considerable delays: It turns out that for TCP Data segments of 1460 bytes, achieving optimal TCP Goodput requires TXOPs of 25 ms, while if one loses only 5% of the optimal Goodput, TXOPs can be of only 3 ms. For TCP Data segments of 256 bytes, the TXOPs are of 13 and 5 ms, respectively.     

Some practical aspects connected with the presence of calcium in soybean oils

Presence of calcium in crude and degummed soybean oils prevents complete elimination of phosphatides by hydration and enhances the formation of heavy precipitates. They block industrial centrifuges at the later stages of the refining processes. Industrially extracted degummed soybean oils contain appreciable amounts of calcium (ca. 100 ppm) and its source was traced to the processed soybeans. Various pre-extraction treatments of the soybeans in industry augment the calcium content in the oils, since crude Soxhlet-extracted soybean oils contained only 15 ppm calcium. Additions at the alkali-refining stages of EDTA or of polyphosphate, to stabilize aqueous suspensions which also contain calcium salts, are suggested as a partial remedy to the frequent blocking of the centrifuges.     

Study of DNA Origami Dimerization and Dimer Dissociation Dynamics and of the Factors that Limit Dimerization

Organizing DNA origami building blocks into higher order structures is essential for fabrication of large structurally and functionally diverse devices and molecular machines. Unfortunately, the yields of origami building block attachment reactions are typically not sufficient to allow programed assembly of DNA devices made from more than a few origami building blocks. To investigate possible reasons for these low yields, a detailed single‐molecule fluorescence study of the dynamics of rectangular origami dimerization and origami dimer dissociation reactions is conducted. Reactions kinetics and yields are investigated at different origami and ion concentrations, for different ion types, for different lengths of bridging strands, and for the “sticky end” and “weaving welding” attachment techniques. Dimerization yields are never higher than 86%, which is typical for such systems. Analysis of the dynamic data shows that the low yield cannot be explained by thermodynamic instability or structural imperfections of the origami constructs. Atomic force microscopy and gel electrophoresis evidence reveal self‐dimerization of the origami monomers, likely via blunt‐end interactions made possible by the presence of bridging strands. It is suggested that this mechanism is the major factor that inhibits correct dimerization and means to overcome it are discussed.     

The geriatric gravida: multifetal pregnancy reduction, donor eggs, and aggressive infertility treatments

OBJECTIVE: Recent technologic advances and societal acceptance have dramatically increased the use of donor eggs for infertile couples who require assisted reproductive technologies. Now many "older" couples can access assisted reproductive technologies to achieve pregnancies. We sought to evaluate the changing pattern of patients referred for multifetal pregnancy reduction as a result of donor eggs and age factors in aggressive infertility treatment. STUDY DESIGN: Patients undergoing multifetal pregnancy reduction from 1986 to 1996 were included and categorized by year groupings, age, and the use of donor eggs. RESULTS: A total of 523 patients were referred for and underwent multifetal pregnancy reduction. Before 1994, only 4 of 226 (1.8%) had received donor eggs, whereas in 1994 to 1996, 29 of 297 (9.8%) had received donor eggs (chi 2 = 12.6, p < 0.001). Eight of 9 patients aged > or = 45 years undergoing multifetal pregnancy reduction received donor eggs. There were no patients aged > or = 45 years before 1994 but 9 in 1994 to 1996. Four of 9 patients aged > or = 45 years with multifetal pregnancies chose reduction to singleton gestation. The proportions of patients aged > or = 40 years have increased from 0% to 11% in the last 8 years. CONCLUSIONS: The availability of donor eggs has dramatically increased the use of assisted reproductive technologies and subsequent use of multifetal pregnancy reduction in older patients. Older patients are more inclined to want reduction to singleton gestation; they cite parental demands, financial issues, and their ability to parent in their 60s and 70s as reasons for reduction to singleton gestation.     

Synthetic mimic of selective transport through the nuclear pore complex

The nuclear pore complex is a large protein channel present universally in eukaryotic cells. It generates an essential macromolecular separation between the nucleus and cytoplasm. The transport mechanism relies on recognition of molecular cargos by receptor proteins, and on specific interaction between the receptors and the pores. We present a chemical mimic of this "receptor-mediated" transport using modified nanoporous membrane filters, polyisopropylacrylamide as the carrier molecule, or receptor, and single-stranded DNA as the cargo. We show that a complex of ssDNA and polyisopropylacrylamide diffuses faster through the modified pores than does the bare ssDNA, in spite of the larger size of the complex. The mobile polymer thus acts as a soluble receptor to usher a macromolecular cargo specifically through the pores.