Synthesis and Solubility Study of the Polyamides Containing 4,4'-(9- fluorenylidene)dianiline in the Backbone as an Antireflecting Spin-on Hardmask Materials

Due to the continuous demand for smaller microelectronic devices, there exists a need to reduce the size of structural shapes in microelectronics and other related industries. Toward this end, effective lithographic techniques are essential to achieve a reduction in the size of microelectronic structures. Typical lithographic processes involve etch resistant photoresist underlying materials having antireflecting properties at a certain wavelength exposure. In this work, such materials were synthesized by the step-polymerization of diamines 2,2'-bis(3-amino- 4-hydroxyphenyl)hexafluoropropane (6FP) and 4,4'-(9-fluorenylidene)dianiline (BAFL) with a variety of diacid chlorides [terepthaloyl, isophthaloyl, glutaryl, and succinyl chlorides] and characterized by 1H NMR in tetrahydrofuran (THF-d8), and gel permeation chromatography (GPC) using polystyrene standards. The effect of the structure of the components on the copolymer solubility in mixture of propylene glycol monoethylether acetate (PGMEA) and cyclohexanone used in microelectronics processing was studied by UV-visible spectroscopy. The solubility of the copolymers was found to be in trade-off relationship with BAFL content needed for its antireflective properties and high plasma etch resistance. The polymers that were prepared by using the equimolar mixture of isophthaloyl dichloride and glutaryl dichloride equimolar mixture showed the best solubility, processability and functionality and are applicable as spin-on antireflecting hardmask materials for deep ultra violet (DUV) litfhography technology. They showed good coatability, chemical resistance, plasma etch resistance, and plasma etch selectivity

Clinical features and outcomes of gastric variceal bleeding: retrospective Korean multicenter data

Background/AimsWhile gastric variceal bleeding (GVB) is not as prevalent as esophageal variceal bleeding, it is reportedly more serious, with high failure rates of the initial hemostasis (>30%), and has a worse prognosis than esophageal variceal bleeding. However, there is limited information regarding hemostasis and the prognosis for GVB. The aim of this study was to determine retrospectively the clinical outcomes of GVB in a multicenter study in Korea.MethodsThe data of 1,308 episodes of GVB (males:females=1062:246, age=55.0±11.0 years, mean±SD) were collected from 24 referral hospital centers in South Korea between March 2003 and December 2008. The rates of initial hemostasis failure, rebleeding, and mortality within 5 days and 6 weeks of the index bleed were evaluated.ResultsThe initial hemostasis failed in 6.1% of the patients, and this was associated with the Child-Pugh score [odds ratio (OR)=1.619; P<0.001] and the treatment modality: endoscopic variceal ligation, endoscopic variceal obturation, and balloon-occluded retrograde transvenous obliteration vs. endoscopic sclerotherapy, transjugular intrahepatic portosystemic shunt, and balloon tamponade (OR=0.221, P<0.001). Rebleeding developed in 11.5% of the patients, and was significantly associated with Child-Pugh score (OR=1.159, P<0.001) and treatment modality (OR=0.619, P=0.026). The GVB-associated mortality was 10.3%; mortality in these cases was associated with Child-Pugh score (OR=1.795, P<0.001) and the treatment modality for the initial hemostasis (OR=0.467, P=0.001).ConclusionsThe clinical outcome for GVB was better for the present cohort than in previous reports. Initial hemostasis failure, rebleeding, and mortality due to GVB were universally associated with the severity of liver cirrhosis

Primordial Germ Cell-Mediated Chimera Technology Produces Viable Pure-Line Houbara Bustard Offspring: Potential for Repopulating an Endangered Species

BACKGROUND: The Houbara bustard (Chlamydotis undulata) is a wild seasonal breeding bird populating arid sandy semi-desert habitats in North Africa and the Middle East. Its population has declined drastically during the last two decades and it is classified as vulnerable. Captive breeding programmes have, hitherto, been unsuccessful in reviving population numbers and thus radical technological solutions are essential for the long term survival of this species. The purpose of this study was to investigate the use of primordial germ cell-mediated chimera technology to produce viable Houbara bustard offspring. METHODOLOGY/PRINCIPAL FINDINGS: Embryonic gonadal tissue was dissected from Houbara bustard embryos at eight days post-incubation. Subsequently, Houbara tissue containing gonadal primordial germ cells (gPGCs) was injected into White Leghorn chicken (Gallus gallus domesticus) embryos, producing 83/138 surviving male chimeric embryos, of which 35 chimeric roosters reached sexual maturity after 5 months. The incorporation and differentiation of Houbara gPGCs in chimeric chicken testis were assessed by PCR with Houbara-specific primers and 31.3% (5/16) gonads collected from the injected chicken embryos showed the presence of donor Houbara cells. A total of 302 semen samples from 34 chimeric roosters were analyzed and eight were confirmed as germline chimeras. Semen samples from these eight roosters were used to artificially inseminate three female Houbara bustards. Subsequently, 45 Houbara eggs were obtained and incubated, two of which were fertile. One egg hatched as a male live born Houbara; the other was female but died before hatching. Genotyping confirmed that the male chick was a pure-line Houbara derived from a chimeric rooster. CONCLUSION: This study demonstrates for the first time that Houbara gPGCs can migrate, differentiate and eventually give rise to functional sperm in the chimeric chicken testis. This approach may provide a promising tool for propagation and conservation of endangered avian species that cannot breed in captivity

Production of germline chimeric chickens by transfer of cultured primordial germ cells

Primordial germ cells (PGCs) from stage 27 (5.5-day-old) Korean native ogol chicken embryonic germinal ridges were cultured in vitro for 5 days. As in in vivo culture, these cultured PGCs were expected to have already passed beyond the migration stage. Approximately 200 of these PGCs were transferred into 2.5-day-old white leghorn embryonic blood stream, and then the recipient embryos were incubated until hatching. The rate of hatching was 58.8% in the manipulated eggs. Six out of 60 recipients were identified as germline chimeric chickens by their feather colour. The frequency of germline transmission of donor PGCs was 1.3–3.1% regardless of sex. The stage 27 PGCs will be very useful for collecting large numbers of PGCs, handling of exogenous DNA transfection during culture, and for the production of desired transgenic chickens