Atomic layer deposition for spacer defined double patterning of sub-10 nm titanium dioxide features.

The next generation of hard disk drive technology for data storage densities beyond 5 Tb/in2 will require single-bit patterning of features with sub-10 nm dimensions by nanoimprint lithography. To address this challenge master templates are fabricated using pattern multiplication with atomic layer deposition (ALD). Sub-10 nm lithography requires a solid understanding of materials and their interactions. In this work we study two important oxide materials, silicon dioxide and titanium dioxide, as the pattern spacer and look at their interactions with carbon, chromium and silicon dioxide. We found that thermal titanium dioxide ALD allows for the conformal deposition of a spacer layer without damaging the carbon mandrel and eliminates the surface modification due to the reactivity of the metal-organic precursor. Finally, using self-assembled block copolymer lithography and thermal titanium dioxide spacer fabrication, we demonstrate pattern doubling with 7.5 nm half-pitch spacer features.

Low temperature dry etching of chromium towards control at sub-5 nm dimensions.

Patterned chromium and its compounds are crucial materials for nanoscale patterning and chromium based devices. Here we investigate how temperature can be used to control chromium etching using chlorine/oxygen gas mixtures. Oxygen/chlorine ratios between 0% and 100% and temperatures between -100 °C and +40 °C are studied. Spectroscopic ellipsometry is used to precisely measure rates, chlorination, and the thickness dependence of n and k. Working in the extremes of oxygen content (very high or very low) and lower temperatures, we find rates can be controlled to nanometers per minute. Activation energies are measured and show that etch mechanisms are both temperature and oxygen level dependent. Furthermore, we find that etching temperature can manipulate the surface chemistry. One surprising consequence is that at low oxygen levels, Etching rates increase with decreasing temperature. Preliminary feature-profile studies show the extremes of temperature and oxygen provide advantages over commonly used room temperature processing conditions. One example is with higher ion energies at -100 °C, where etching products deposit.

Directed Self-Assembly of Poly(2-vinylpyridine)-b-polystyrene-b-poly(2-vinylpyridine) Triblock Copolymer with Sub-15 nm Spacing Line Patterns Using a Nanoimprinted Photoresist Template.

Low molecular weight P2VP-b-PS-b-P2VP triblock copolymer (poly(2-vinlypyridine)-block-polystyrene-block-poly(2-vinylpyridine)] is doped with copper chloride and microphase separated into lamellar line patterns with ultrahigh area density. Salt-doped P2VP-b-PS-b-P2VP triblock copolymer is self-assembled on the top of the nanoimprinted photoresist template, and metallic nanowires with long-range ordering are prepared with platinum-salt infiltration and plasma etching.

Solvent-assisted directed self-assembly of spherical microdomain block copolymers to high areal density arrays.

The fabrication process for 5 Tb/in(2) bit patterns using solvent-assisted directed self-assembly is investigated. The N-methyl-2-pyrrolidone solvent vapor-annealing method was used to achieve good long-range lateral ordering of low-molecular-weight polystyrene-block-polydimethylsiloxane with a lattice spacing of 11 nm on flat Si substrates, PS modified substrates and lithographically patterned substrates, respectively.

Fabrication of silicon oxide nanodots with an areal density beyond 1 teradots inch(-2).

The combination of solvent annealing, surface reconstruction, and a tone-reversal etching procedure provides an attractive approach to utilize block copolymer (BCP) lithography to fabricate highly ordered and densely packed silicon oxide nano-dots on a surface. The obtained silicon oxide nano-dots feature an areal density of 1.3 teradots inch(-2) .

Aligned nanowires and nanodots by directed block copolymer assembly.

The directed self-assembly of block copolymers (BCPs) is a promising route to generate highly ordered arrays of sub-10 nm features. Ultradense arrays of a monolayer of spherical microdomains or cylindrical microdomains oriented parallel to the surface have been produced where the lateral ordering is guided by surface patterning and the lattice defined by the patterning can be commensurate or incommensurate with the natural period of the BCP. Commensurability between the two can be used to elegantly manipulate the lateral ordering and orientation of the BCP microdomains so as to form well-aligned arrays of 1D nanowires or 2D addressable nanodots. No modification of the substrate surface, aside from the patterning, was used, making the influence of lattice mismatch and pattern amplification on the size, shape and pitch of the BCP microdomains more transparent. A skew angle between incommensurate lattices, defining a stretching or compression of the BCP chains to compensate for the lattice mismatch, is presented.

Helicobacter pylori infection in Korea.

Helicobacter pylori is a gram-negative bacterium that was first isolated in 1982. Since then, H. pylori infection in humans has been shown to be associated with gastritis, peptic ulcer disease, gastric carcinoma, and mucosa-associated lymphoid tissue (MALT) lymphoma as well. The epidemiology, transmission, and pathogenicity of H. pylori has been a subject of intensive study. Successful treatment improves the cure rate of peptic ulcerations and treatment with antimicrobials also decreases the recurrence rate of these diseases. Better regimens having less toxicity and a good eradication rate have also been developed. A better understanding of the pathophysiologic mechanisms relating to H. pylori induced mucosal damages would result in more options for the prevention of peptic ulcers and carcinogenesis. Korea has a relatively high incidence of H. pylori infection and gastric cancer. Growing interest has developed in view of its importance in being associated with various gastroduodenal diseases. Furthermore, along with a high incidence of H. pylori-related disease in Korea, because the interaction between H. pylori, host factors and environmental factors is important in disease pathogenesis, we need to have precise data on the characteristics of H. pylori-related diseases that occur in Korea. In the present report we review the epidemiology, transmission route, diagnosis, pathogenesis, treatment methods and relationship with gastroduodenal diseases with in special references to basic and clinical data that have been published.

Fatty acid patterns in gastric mucosa of stomach cancer patients.

omega6 and omega3 fatty acids are important cellular components and known to be involved in disease processes. However, few studies have focused on mucosa fatty acid in human gastric cancer. The purpose of this study was to investigate how fatty acid patterns of mucosa are altered in gastric cancer. Fatty acids were analyzed by gas chromatography and their relative compositions (%) were determined and evaluated both in mucosa total-fatty acids and in phospholipid-fatty acids in paired cancerous and non-cancerous gastric cancer tissues (n = 18). The level of arachidonic acid (20:4omega6, AA) appeared significantly higher both in phospholipid-fatty acids (p < 0.05) and in total-fatty acids (p < 0.001) in cancerous mucosa compared to non-cancerous mucosa. The omega6/omega3 fatty acid ratio of phospholipid-fatty acids was also significantly higher in cancerous mucosa. The higher level of AA in cancerous tissue can be partially explained by the higher ratio of 20:4omega 6/20:3omega6 (desaturation index) and the lower ratio of 22:4omega6/20:4 omega6 (elongation index). The change in the relative composition of arachidonic acid may influence the production of prostaglandins and related metabolites, which regulate cell differentiation and proliferation. The findings of this study with respect to fatty acid changes, especially in terms of arachidonic acid metabolism, may be of relevance in the understanding of the roles of specific fatty acids and possibly of eicosanoids in gastric cancer.

Serum concentrations of antioxidant nutrients in healthy American, Chinese and Korean adults.

Population variabilities of serum carotenoid and tocopherol levels using reverse-phase HPLC in healthy American (Caucasian), Chinese and Korean adults were determined. Considerable variation in serum nutrient concentrations was found among these groups. The mean serum concentration of lutein/zeaxanthin was significantly higher in the Chinese than in the white Americans (p<0.001), whereas serum α-carotene and lycopene concentrations were significantly higher in white Americans than in Chinese (p<0.001). Serum ß-carotene concentrations in Koreans were significantly higher than in either white Americans or in Chinese. The mean serum lycopene concentration in Koreans was lower than in Americans. The mean serum retinol concentration was significantly higher in white Americans than in Chinese or Koreans (p<0.005). American serum γ-tocopherol concentrations were significantly higher (p<0.005) than those of the Chinese, whereas γ-tocopherol values were significantly lower (p<0.001) than those of the Chinese. These differences probably reflect differences in dietary intakes among these population groups.

Endogenous carotenoid concentrations in cancerous and non-cancerous tissues of gastric cancer patients in Korea.

Carotenoid concentrations were measured in serum and in both non-cancerous and cancerous gastric mucosal tissues of Korean patients with gastric cancer (n = 18). Carotenoids in serum and gastric tissue were extracted with chloroform/methanol (2:1), and measured using reverse-phase high-performance liquid chromatography with a C30 column. Cryptoxanthin and -carotene were the major carotenoids in the Korean blood and they had a median ratio of non-cancerous tissue/serum levels which was less than 1.0. No significant differences of cryptoxanthin and -carotene levels were found between non-cancerous and cancerous tissues. After incubation of -carotene with gastric tissue, significantly higher levels of -carotene breakdown products were produced in the homogenates of cancerous tissue when compared with non-cancerous tissue. Lutein, zeaxanthin and -carotene were the minor carotenoid constituents in the blood and their median ratio of non-cancerous tissue/serum levels was greater than 1.0. Cancerous tissue had significantly lower levels of lutein, zeaxanthin and -carotene than did non-cancerous tissue. It appears that the increased breakdown of -carotene and cryptoxanthin in cancerous tissue can be compensated for by an increased uptake of circulating carotenoids by cancerous tissue, whereas lutein, zeaxanthin and -carotene levels in cancerous tissue are not able to be maintained.

Correlation between carotenoid concentrations in serum and normal breast adipose tissue of women with benign breast tumor or breast cancer.

To evaluate the relationship between carotenoid concentrations in serum and breast tissue, we measured serum carotenoid concentrations and endogenous carotenoid levels in breast adipose tissue of women with benign breast tumor (n = 46) or breast cancer (n = 44). Before extraction, serum was digested with lipase and cholesterol esterase, and breast adipose tissue was saponified. Serum and tissue carotenoids were extracted with ether/hexane and measured by using HPLC with a C30 column. Serum retinoic acid was extracted with chloroform/methanol and measured using HPLC with a C18 column. There were no significant differences in serum carotenoids [lutein, zeaxanthin, cryptoxanthin (both alpha- and beta-), alpha-carotene, all-trans beta-carotene, 13-cis beta-carotene and lycopene], retinoids (retinol, all-trans and 13-cis retinoic acids), and alpha- and gamma- tocopherol concentrations between benign breast tumor patients and breast cancer patients. A substantial amount of 9-cis beta-carotene was present in adipose tissue and was the only carotenoid that had a significantly lower level in benign breast tumor patients than in breast cancer patients. Correlations between carotenoid concentrations in serum and in breast adipose tissue were determined by combining the data of the two groups. Concentrations of the major serum carotenoids except cryptoxanthin showed significant correlations with breast adipose tissue carotenoid levels. When the concentrations of serum carotenoids were adjusted for serum triglycerides or LDL, correlations between serum carotenoid concentrations and breast adipose tissue carotenoid levels markedly increased, including that of cryptoxanthin (P <0. 001). The strong correlation between serum carotenoid concentrations and endogenous breast adipose tissue carotenoid levels indicate that dietary intake influences adipose tissue carotenoid levels as well as serum concentrations, and that adipose tissue is a dynamic reservoir of fat-soluble nutrients.

Relationship between fatty acid compositions and taurine concentration in breast milk from Chinese rural mothers.

Long chain ω3 and ω6 fatty acids and taurine have been suggested to have structural and/or functional roles in the brain. In this study the levels of fatty acids and taurine in breast milk and their correlations were investigated in 46 lactating women from an area 100 km north-east of Beijing, China. The subjects consisted of two groups: group 1 was 22-47 days postpartum and group 2 was 75-106 days postpartum. Fatty acids and taurine in breast milk were measured by gas-liquid chromatography and high-performance liquid chromatography, respectively. The relative compositions of long chain ω6 and ω3 fatty acids decreased significantly (20:3 ω6, 20:4 ω6, 22:4 ω6, 22:5 ω6 and 22:6 ω3; all P < 0.01) in the course of lactation, while long chain saturated (20:0, 22:0) and monounsaturated (20:1, 22:1) fatty acids tended to increase. The ratio of ω6/ω3 fatty acids in breast milk fat appeared to be higher (12.3 ± 4.3 for group 1, and 16.5 ± 7.4 for group 2) than the desired range of 4-10. Breast milk taurine concentrations from Chinese rural mothers were 186 ± 48 nmol/mL and 157 ± 65 nmol/mL for groups 1 and 2, respectively. A significantly inverse relationship was observed between breast milk taurine concentration and the ratio of arachidonic acid ω6 to docosahexaenoic acid ω3 (r = -0.323, P = 0.028). Further studies on the physiological function(s) of taurine as an antioxidant and as a neurotransmitter are worth pursuing in relation to the balance of long chain ω6 and ω3 fatty acids, especially as regards its role in retina and brain development.

Serum levels of antioxidant vitamins in relation to coronary artery disease: a case control study of Koreans.

With the changes in trends of disease pattern from infectious to chronic degenerative disease, cardiovascular disease has been considered as the major cause of death in Korea. Numerous studies have been done on the antioxidant effects of some vitamins in the prevention of chronic illness, but not many in relation to the cardiovascular disease. Therefore, the relation between antioxidant vitamins, mainly alpha-tocopherol (alpha-T) and beta-carotene (beta-C), and coronary artery disease (CAD) such as angina pectoris and myocardial infarction has been investigated in this study. The blood samples were obtained from the CAD patients who were angiographically diagnosed within a month (100 case group). Patients who had an experience of PTCA or CABG were excluded from the study. Control subjects were healthy adults who had normal EKG values, no chest pain and no past history of cardiac disease (100 control group). All subjects were free for serum lipid lowering drugs. Serum alpha-T and beta-C were analysed using HPLC. In addition to antioxidant vitamins, serum lipids (total cholesterol, HDL, TG) were also measured. Each case and control was matched in terms of age and sex. And all the CAD risk factors such as blood pressure, smoking, alcohol, serum lipid profile and BMI were adjusted to determine pure effect(s) of alpha-T and beta-C on the CAD. The concentrations of both alpha-T and beta-C were significantly lower in the CAD group than those in control group (P < 0.05); in CAD group, mean values of alpha-T and beta-C were 11.9 +/- 7.2 (micrograms/ml), 35.8 +/- 3.1 (micrograms/dl) respectively. As for the levels of beta-C, it shows inverse relation with age, but not for the alpha-T levels. Serum levels of both vitamins did not show any significant differences in terms of sex, but men have a tendency o higher levels of beta-C, but lower levels of alpha-T.

Similar metabolites formed from beta-carotene by human gastric mucosal homogenates, lipoxygenase, or linoleic acid hydroperoxide.

To determine the basis for the formation of excentric cleavage products of beta-carotene (beta-C) after incubation with human gastric mucosal homogenates, we have studied the effect of lipoxygenase in beta-C metabolism. beta-C was incubated with human gastric mucosal homogenates, soybean lipoxygenase with linoleic acid, or the lipoxygenase primary product, 13(S)-hydroperoxycis,trans-9,11-octadecadienoic acid (13-LOOH). The beta-C metabolites, beta-apo-14', -12', -10', and -8'-carotenals, beta-apo-13-carotenone, retinoic acid, and retinal were detected and quantified by HPLC after a 30-min incubation with 1.8 microM beta-C. The products from the lipoxygenase plus linoleic acid incubation and from the lipoxygenase primary product, 13-LOOH, with beta-C were exactly the same as the products from a human gastric mucosal homogenate incubation. Significantly larger amounts of the same beta-C metabolites were formed when beta-C was incubated with gastric mucosal homogenates and lipoxygenase together. Furthermore, nordihydroguaiaretic acid (NDGA), a specific lipoxygenase inhibitor, was found to significantly inhibit the formation of beta-apo-carotenoids and retinoids produced by gastric mucosal homogenates incubated with beta-C. The similarity of the beta-C metabolites when beta-C was incubated with human gastric mucosal homogenate, lipoxygenase plus linoleic acid, or 13-LOOH and the inhibition of beta-C metabolite production by NDGA in gastric tissue incubation with beta-C suggest that lipoxygenase is involved in beta-C metabolism in gastric mucosa. The activity of 13-LOOH in our hands would indicate that an enzyme-linked process is occurring in gastric tissue producing fatty acid hydroperoxides, and that the hydroperoxide, or a radical species derived from it, is able to carry out the oxidation of beta-C independently of the enzyme.

Enterohepatic circulation of newly administered alpha-tocopherol in the rat.

We have measured the magnitude of the enterohepatic circulation of newly administered [3H]-alpha-tocopherol in rats. One group of animals (day-1 rats) was used to prepare [3H]-alpha-tocopherol-containing lymph. Another set of animals (day-2 rats) was divided into control and vitamin E supplemented (+E) groups, which were used to study the enterohepatic circulation of [3H]-alpha-tocopherol from day-1 rat lymph administered into the jugular vein of day-2 rats. Mesenteric lymph duct and common bile duct cannulations were performed. The enterohepatic circulation in day-2 rats of intrajugularly administered [3H]-alpha-tocopherol in chylomicrons was found to be 1.78 +/- 0.23% for control and 0.98 +/- 0.08% for +E rats (p less than 0.01). A considerable quantity (13.3 +/- 4.3% in control vs 19.2 +/- 4.7% in +E) of [3H]-radioactivity was recovered in bile over 24 h, of which pure [3H]-alpha-tocopherol was 3.17% in control and 1.04% in +E bile. More than 95% of [3H]-radioactivity recovered in day-2 control and +E bile was more polar than alpha-tocopherol shown by high performance liquid chromatography (HPLC). In contrast, more than 95% of [3H]-radioactivity appearing in day-2 lymph was unchanged alpha-tocopherol. Thus, the magnitude of enterohepatic circulation of alpha-tocopherol is very small in rats. Quantitation of the enterohepatic circulation of vitamin E under different physiological conditions remains to be investigated.