Material issues for nanoporous ultra low-k dielectrics

Using the molecularly designed porogen (pore generating agent) approach, novel nanoporous low-k materials with improved mechanical properties have been achieved based on poly(methylsilsesquioxane), PMSSQ, structure. Two different methods, microphase separation system and grafted porogen system, were adopted to realize nonporous ultra low-k dielectrics with superior mechanical properties. We found that the behavior of dielectric constant as well as thin film modulus depends on the molecular structure of a porogen. Within the decomposition temperature windows of grafted porogens, a low-k material with k 6 Gpa was achieved. These results indicate that it is possible to design and fabricate nanoporous thin films with balanced low dielectric constant and robust mechanical properties, which are highly desired for microelectronic industry.This work is supported by the Collaborative Project for Excellence in Basic System IC Technology. Financial supports from the Ministry of Science and Technology (MOST) (the National Research Laboratory Fund) and the Korean Ministry of Education through the Brain Korea 21 Program are also greatly acknowledged

Synthesis of Porous Silica with Hierarchical Structure Directed by a Silica Precursor Carrying a Pore-Generating Cage

We have obtained a new class of porous silica with good structural order and additional corrugated nanopores clustered around the primary mesopores from the co-condensation of TEOS and adamantylphenol-grafted trimethoxysilane (adam-graft SQ) using a triblock Pluronic P123 (EO20PO70EO20,Mw = 5800) copolymer as a structure-directing agent. Thermally activated removal of pore-generating moieties (i.e., adamantylphenol groups) in adam-graft SQ involves the generation of secondary micro-to-small mesopores, while the block copolymer template generates 2D-hexagonal mesopores. We found that the mesostructural characteristics and the generation of secondary indented pores right next to the mesopores can be tailored by the addition order of the two silica precursors (TEOS and adam-graft SQ), varying the molar ratio between TEOS and adam-graft SQ in the starting sol mixture, and the degree of silica polymerization. The increase in the hexagonal unit cell parameters is attributed to the increment of pore size originating from the removal of adamantylphenol moieties. It is believed that the hydrophobicity of adamantylphenol groups plays a key role in its selective incorporation into the region near the PPO core blocks and the subsequent generation of corrugated pores along the silica channels resulting in the increase of pore diameter.This work was financially supported by the Korea Science and Engineering Foundation (KOSEF) grant through the Acceleration Research Program (R17-2007-059-01000-0) and the NANO Systems Institute – National Core Research Center (R15-2003-032-02002-0) funded by the Ministry of Education, Science and Technology (MEST) and the Brain Korea 21 Program endorsed by the MEST. Financial support from the Korean Collaborative Project for Excellence in Basic System IC Technology (System IC 2010) is also greatly acknowledged

Estimation of Stellate Ganglion Block Injection Point Using the Cricoid Cartilage as Landmark Through X-ray Review

BACKGROUND: Stellate ganglion block is usually performed at the transverse process of C6, because the vertebral artery is located anterior to the transverse process of C7. The purpose of this study is to estimate the location of the transverse process of C6 using the cricoid cartilage in the performance of stellate ganglion block. METHODS: We reviewed cervical lateral neutral-flexion-extension views of 48 patients who visited our pain clinic between January and June of 2010. We drew a horizontal line at the surface of the cricoid cartilage in the neutral and extension views of cervical lateral x-rays. We then measured the change in the shortest distance from this horizontal line to the lowest point of the transverse process of C6 between the neutral and extension views. RESULTS: There was a statistically significant difference in the shortest distance from the horizontal line at the surface of the cricoid cartilage to the lowest point of transverse process of C6 between neutral position and neck extension position in both males and females, and between males and females in both neutral position and neck extension position. The cricoid cartilage level was 4.8 mm lower in males and 14.4 mm higher in females than the lowest point of transverse process of C6 in neck extension position. CONCLUSIONS: Practitioners should recognize that the cricoid cartilage has cephalad movement in neck extension. In this way, the cricoid cartilage can be still useful as a landmark for stellate ganglion block.ope

Genetic analysis of ORF5 of recent Korean porcine reproductive and respiratory syndrome viruses (PRRSVs) in viremic sera collected from MLV-vaccinating or non-vaccinating farms

The 23 open reading frame (ORF) 5 sequences of Korean type II porcine reproductive and respiratory syndrome virus (PRRSV) were collected from viremic sera from the (modified live vaccine) MLV-vaccinating and non-vaccinating farms from 2007 to 2008. The samples were phylogenetically analyzed with previous ORF5 sequences, including type I Korean PRRSV, and previously reported or collected sequences from 1997 to 2008. A MN184-like subgroup of type II Korean PRRSV was newly identified in the viremic sera collected from 2007 to 2008. And of the type I PRRSVs, one subgroup had 87.2~88.9% similarity with the Lelystad virus, showing a close relationship with the 27~2003 strain of Spain. The maximum parsimony tree of type II PRRSV from 1997 to 2008 showed that they had evolved to four lineages, subgroups 1, 2, 3 and 4. Most of the recently collected type II PRRSVs belonged to subgroup 4 (48%). The region of three B-cell epitopes and two T-cell epitopes of ORF5 amino acids sequences was considerably different from the MLV in subgroups 3 and 4. In conclusion, the existence of type I PRRSV, which was genetically different from Lelystad virus (Prototype of type I PRRSV), and heterologous type II PRRSVs of viremic pigs detected even in the MLV-vaccinating farms indicated the need for new vaccine approaches for the control of PRRSV in Korea

Relationship between Vitamin D, Parathyroid Hormone, and Bone Mineral Density in Elderly Koreans

There is controversy regarding definition of vitamin D inadequacy. We analyzed threshold 25-hydroxyvitamin D (25[OH]D) below which intact parathyroid hormone (iPTH) increases, and examined age- and sex-specific changes of 25(OH)D and iPTH, and association of 25(OH)D and iPTH with bone mineral density (BMD) in elderly Koreans. Anthropometric parameters, serum 25(OH)D and iPTH, lumbar spine and femur BMD by dual-energy radiography absorptiometry (DXA) were measured in 441 men and 598 postmenopausal women. iPTH increased below serum 25(OH) of 36.7 ng/mL in men, but failed to reach plateau in women. Femur neck BMD above and below threshold differed when threshold 25(OH)D concentrations were set at 15-27.5 ng/mL in men, and 12.5-20 ng/mL in postmenopausal women. Vitamin D-inadequate individuals older than 75 yr had higher iPTH than those aged ≤ 65 yr. In winter, age-associated iPTH increase in women was steeper than in summer. In conclusion, vitamin D inadequacy threshold cannot be estimated based on iPTH alone, and but other factors concerning bone health should also be considered. Older people seemingly need higher 25(OH)D levels to offset age-associated hyperparathyroidism. Elderly vitamin D-inadequate women in the winter are most vulnerable to age-associated hyperparathyroidism

Simultaneous Detection of EGFR and VEGF in Colorectal Cancer using Fluorescence-Raman Endoscopy

Fluorescence endomicroscopy provides quick access to molecular targets, while Raman spectroscopy allows the detection of multiple molecular targets. Using a simultaneous fluorescence-Raman endoscopic system (FRES), we herein demonstrate its potential in cancer diagnosis in an orthotopically induced colorectal cancer (CRC) xenograft model. In the model, epidermal growth factor receptor (EGFR) and vascular endothelial growth factor (VEGF) were targeted with antibody-conjugated fluorescence and surface-enhanced Raman scattering (F-SERS) dots. FRES demonstrated fast signal detection and multiplex targeting ability using fluorescence and Raman signals to detect the F-SERS dots. In addition, FRES showed a multiplex targeting ability even on a subcentimeter-sized CRC after spraying with a dose of 50 µg F-SERS dots. In conclusion, molecular characteristics of tumor cells (EGFR in cancer cell membranes) and tumor microenvironments (VEGF in the extracellular matrix) could be simultaneously investigated when performing a colonoscopy

Preparation of Nanoporous Poly(methyl silsesquioxane) Thin Films Derived from Chemically Linked Carbon Cages

This work was supported by the Korean Collaborative Project for Excellence in Basic Systems IC Technology (98-B4-CO-00-01-00-02). Financial supports from the Ministry of Education of Korea through the Brain Korea 21 Program the National Research Laboratory Fund (M1-0104-00-0191), and Thin Film Solutions are also acknowledged

Genome sequence of type strain of Staphylococcus aureus subsp aureus

Background: Staphylococcus aureus is a pathogen that causes food poisoning and community-associated infection with antibiotic resistance. This species is an indigenous intestinal microbe found in infants and not found in adult intestine. The relatively small genome size and rapid evolution of antibiotic resistance genes in the species have been drawing an increasing attention in public health. To extend our understanding of the species and use the genome data for comparative genomic studies, we sequenced the type strain of S. aureus subsp. aureus DSM 20231T. Results: Seventeen contigs were generated using hybrid assembly of sequences derived from the Roche 454 and Illumina systems. The length of the genome sequence was 2,902,619 bases with a G + C content of 32.8%. Among the 2,550 annotated CDSs, 44 CDSs were annotated to antibiotic resistance genes and 13 CDSs were related to methicillin resistance. It is interesting to note that this strain was first isolated in 1884 before methicillin was generally used on patients. Conclusions: The present study analyzed the genome sequence of S. aureus subsp. aureus type strain as the reference sequence for comparative genomic analyses of clinical isolates. Methicillin resistance genes found in the genome indicate the presence of antibiotic resistance mechanism prior to the usage of antibiotics. Further comparative genomic studies of methicillin-resistant strains based on this reference genome would help to understand the evolution of resistance mechanism and dissemination of resistance genes.Y