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An alternative catalytic method was employed using the reduction of Pd ions on the surface of cetyltrimethylammonium bromide (CTAB) treated laponite to initiate the electroless plating of copper; the deposition features of the Pd nanoparticles produced were investigated in detail. Results indicated intercalation and reduction of Pd nanoparticles occurred at room temperature and involved interaction between the laponite and the cetyltrimethylammonium cationic templates. Organic species and amount on laponite were optimized to adjust silicate platelet interlayer distances and platelet organophilic properties. Intercalation of Pd nanoparticles occurred between the magnesium silicate layers of laponite and this was dependent on pre-treatment and impregnation times. As impregnation is a method of producing heterogeneous catalysts, we considered Pd nanoparticles on laponite templates could catalyze the electroless deposition of Cu to initiate metallization. Cu films fabricated on laponite templates exhibited excellent surface roughness (˜1.7 nm) and low resistivity (˜3.42 μΩ). The devised approach enabled the facile formation of a network suitable for Cu metallization without causing substrate damage and produced metal surfaces with excellent flatness and resistivity.

Boron-diffused samples passivated by Al2O3/TiO2 stacks with different types of TiO2 were investigated. An emitter saturation current density of 11 × 10−15 A/cm2 was obtained for Al2O3/TiO2 passivated samples with symmetrical 100 Ω/sq. boron diffusion. The surface passivation of Al2O3/TiO2 stacks was strongly impacted by the temperature, gas, and sequence during two-step annealing. In addition, the saturation current density of the Al2O3/TiO2 stacks is influenced by the TiO2 layers with an O3 treatment. Enhanced passivation performance of the Al2O3/TiO2 stacks was achieved by a combination of appropriate TiO2 capping layer and post-annealing. The results of this study provide reliable criteria for the design of thermally-stable Al2O3/TiO2 stacks on high-efficiency silicon solar cells.

The characteristics of laser ablation prepared on the structures of a passivated emitter and rear cell (PERC) using additional laser irradiation were investigated. Particular emphasis was placed on the distribution of laser damage and contact geometry on the cell performance. The residual Al2O3 passivation layer of the Al2O3/SiNx passivated samples was removed almost completely by three laser shots. No severe damage profile was observed near the silicon surface, but damage profiles with a thickness of 10–15 nm were observed in the form of amorphous silicon. Additional laser irradiation after contact opening generally degraded the passivation quality with increasing laser shots, and the depth of laser-induced damage was a few micrometers. Interestingly, the PERC cells fabricated using three laser shots had higher efficiency than that produced by one laser shot. This was attributed to the chemical reaction between the silicon and Al paste, resulting in a eutectic alloy and back surface field, which was much thicker than the depth of laser damage. Consequently, the laser damage by the ablation process can be recovered by metallization during the fabrication of PERC cells. The experimental analyses highlighted that the fraction of point contact is a fundamental parameter in the design of PERC cells. The reduction of fraction of point contacts to reduce the recombination losses at rear surface led to an increase of series resistance. Therefore it is necessary to optimize the width and pitch of point contacts for high-efficiency solar cells.

N-type phosphorus diffusion in silicon using phosphorus oxychloride, POCl3, has been widely used in the production of p-type silicon solar cells. The thermal diffusion process in a furnace generally involves two steps: pre-deposition and drive-in. The phosphorous doping by thermal diffusion often shows high surface concentrations, leading to an increase in charge recombination, which should be inhibited in order to fabricate high efficiency silicon solar cells. In this study, we investigate the influence of 3 drive-in steps at sequentially increasing temperatures during the POCl3 diffusion on the emitter performance. As a result, it was found that the kink region was made shorter while maintaining surface concentration for a good metal contact without losing its passivation quality. This result is attributed to the higher active dopant concentration of the 3 drive-in step samples, leading to a lower series resistance and higher fill factor in the PERC solar cells. The results show that slight changes in the PSG process conditions can contribute to the improvement of high efficiency solar cells.

Al2O3/TiO2 stacks formed by atomic layer deposition are known to provide a high level of passivation for boron-doped silicon. In previous works, the TiO2 layer was deposited on a pre-annealed Al2O3 layer, however this stack showed passivation degradation after post-deposition annealing. This work presents an alternative to using the as-deposited Al2O3 for the Al2O3/TiO2 stack, which shows no degradation of passivation after post-deposition annealing up to 400 °C. This approach simplifies the processing, allowing continuous layer deposition, and eliminates the undesirable vacuum breaking. This simplified processing leads to better thermal stability of the Al2O3/TiO2 stacks and a low emitter saturation current density. In order to understand the underlying mechanism of surface passivation, an investigation on the effect of thermal SiO2 on the passivation of the Al2O3/TiO2 stack was performed, which indicates that the TiO2 capping layer enhances the field-effect passivation for both the Si/Al2O3 and SiO2/Al2O3 structures.

Gapless interdigitated back contact (IBC) solar cells were fabricated with phosphorous back surface field on a boron emitter, using an ion implantation process. Boron emitter (boron ion implantation) is counter doped by the phosphorus back surface field (BSF) (phosphorus ion implantation) without gap. The gapless process step between the emitter and BSF was compared to existing IBC solar cell with gaps between emitters and BSFs obtained using diffusion processes. We optimized the doping process in the phosphorous BSF and boron emitter region, and the implied Voc and contact resistance relationship of the phosphorous and boron implantation dose in the counter doped region was analyzed. We confirmed the shunt resistance of the gapless IBC solar cells and the possibility of shunt behavior in gapless IBC solar cells. The highly doped counter doped BSF led to a controlled junction breakdown at high reverse bias voltages of around 7.5 V. After the doping region was optimized with the counter doped BSF and emitter, a large-area (5 inch pseudo square) gapless IBC solar cell with a power conversion efficiency of 22.9% was made.

Silicon oxynitride (SiON) could be used in combination with silicon nitride (SiN) to form a multilayer anti-reflection coating on the front side of selective emitter solar cells. In this study, these double anti-reflection layers were fabricated by a continuous deposition technique using the plasma enhanced chemical vapor deposition method. We attempted to determine whether this method is fast and cost effective and can achieve higher efficiency for solar cell manufacture. The results show that the short circuit current density for the double layer anti-reflection coating on selective emitter solar cells was higher by 0.5 mA/cm2 compared to the single layer coating owing to the improved optical reflectance. The incorporation of a SiN/SiON stack into the anti-reflection layer of the CZ selective emitter solar cells yields an energy conversion efficiency of 19.4%, which is higher than the efficiency (19.18%) for the reference solar cells with single layer SiN anti-reflection coating.

Copper has unique properties, such as low electrical resistivity, that are exploited in a number of applications, including an interconnect layer in integrated circuits and microelectronic devices. Etching techniques are essential for the fabrication of fine structures, devices, and circuits. This article addresses the methods of copper etching with an emphasis on approaches using ferric nitrate. Potentiodynamic polarization tests using benzotriazole as an inhibitor showed that ferric nitrate has higher inhibition efficiency than conventional etchants. This is because benzotriazole in a ferric nitrate solution is adsorbed on the copper surface to a greater extent than in a ferric chloride and cupric chloride solution, as confirmed by Fourier transform infrared analysis. Quantitative atomic force microscopy characterization showed that good surface quality with significantly lower surface roughness can be obtained from a copper film etched in a ferric nitrate solution, which has potential use in microelectronics manufacturing.

The illuminated current-voltage characteristics of Cu(In,Ga)(S,Se)2 (CIGSSe) thin film solar cells fabricated using two different buffer layer processes: chemical bath deposition (CBD) and atomic layer deposition (ALD) were investigated. The CIGSSe solar cell with the ALD buffer showed comparable conversion efficiency to the CIGSSe solar cell with CBD buffer but lower shunt resistance even though it showed lower point shunt defect density as measured in electroluminescence. The shunt paths were investigated in detail by capturing the high-resolution dark lock-in thermography images, resolving the shunt resistance contributions of the scribing patterns (P1, P3), and depth profiling of the constituent elements. It was found that the concentration of Na from the soda-lime glass substrate played a key role in controlling the shunt paths. In the ALD process, Na segregated at the surface of CIGSSe and contributed to the increase in the shunt current through P1 and P3, resulting in a reduction in the fill factor of the CIGSSe solar cells.

Silicon solar cells passivated with Al2O3 require a capping layer that protects the passivation layer from humidity because of sensitivity of Al2O3 to moisture. Al2O3/TiO2 stacks obtained by atomic layer deposition have been known to provide a high level of passivation layers because of their excellent field-effect passivation. In this work, degradation of this Al2O3/TiO2 stack, when exposed to humidity, is examined, and an attempt is made for a humidity-resistant encapsulation layer by adding Al2O3/TiO2 nanolaminates that can be deposited in-situ without breaking vacuum. Placing the nanolaminate on top of the TiO2 and Al2O3 stack is found to lead to almost no degradation even after 10 days of humidity exposure. (© 2015 WILEY-VCH Verlag GmbH &Co. KGaA, Weinheim)

The spin-coating method, which is widely used for thin film device fabrication, is incapable of large-area deposition or being performed continuously. In perovskite hybrid solar cells using CH(3)NH(3)PbI(3) (MAPbI(3)), large-area deposition is essential for their potential use in mass production. Prior to replacing all the spin-coating process for fabrication of perovskite solar cells, herein, a mesoporous TiO(2) electron-collection layer is fabricated by using the electro-spray deposition (ESD) system. Moreover, impedance spectroscopy and transient photocurrent and photovoltage measurements reveal that the electro-sprayed mesoscopic TiO(2) film facilitates charge collection from the perovskite. The series resistance of the perovskite solar cell is also reduced owing to the highly porous nature of, and the low density of point defects in, the film. An optimized power conversion efficiency of 15.11% is achieved under an illumination of 1 sun; this efficiency is higher than that (13.67%) of the perovskite solar cell with the conventional spin-coated TiO(2) films. Furthermore, the large-area coating capability of the ESD process is verified through the coating of uniform 10 × 10 cm(2) TiO(2) films. This study clearly shows that ESD constitutes therefore a viable alternative for the fabrication of high-throughput, large-area perovskite solar cells.

We investigate the effect of O3 and H2O oxidant pre-pulse prior to Al2O3 atomic layer deposition for Si surface passivation. Interfacial oxide SiOx formed by the O3 pre-pulse is more beneficial than that by H2O to a high level of surface passivation. The passivation of thinner H2O–Al2O3 films is more improved by this O3 pre-pulse. O3 pre-pulse for 10 nm H2O–Al2O3 reduces saturation current density in boron emitter to 18 fA cm–2 by a factor of 1.7. Capacitance–voltage measurements reveal this interfacial oxide plays a role of decreasing interface trap density without detrimental effect to negative charge density of Al2O3. (© 2014 WILEY-VCH Verlag GmbH &Co. KGaA, Weinheim)

films from damp-heat stress.Two degradation regimes are proposed to explain thedegradation: (i) initial reversible degradation at shorter timeexposures, which is ascribed to the loss of field effectpassivation; (ii) severe degradation after longer term exposure,which is believed to be due to a substantial loss of chemicalpassivationwiththegenerationofnewspeciesfromthereactionof Al

Chemical processes are very important for the development of high-efficiency crystalline solar cells, mainly for surface texturing to improve light absorption and cleaning processes to reduce surface recombination. Recently, research has been focusing on the impact of chemical polishing on the performance of a passivated emitter and rear cells (PERC), with particular emphasis on the dielectric passivation layers on the front side. This study examined the influence of etching on the passivation of Al2O3/TiO2 stacks, where the films may each be deposited using a range of deposition and post-annealing parameters. Most TiO2 films deposited at 300 &deg, C were resistant to chemical etching, and higher temperature deposition and annealing produced more chemical-resistant films. TiO2 films deposited at 100 &deg, C were etched slightly by SC1 and SC2 solutions at room temperature, whereas they were etched at a relatively high rate in an HF solution, even when capped with a thick TiO2 layer (up to 50 nm in thickness), blistering occurred in 20-nm-thick Al2O3 films. In contrast to the as-deposited films, the annealed films showed a lower level of passivation as 1% HF etching proceeded. The implied open circuit voltage of the samples annealed at 300 &deg, C after HF etching decreased more than those annealed at 400 &deg, C. The dark area in the photoluminescence images was not resistant to the HF solution and showed more etch pits. The etching strategies developed in this study are expected to help setup integration processes and increase the applicability of this stack to solar cells.

In this work atomic layer deposition of Al2O3 and TiO2 has been used to obtain dielectric stacks for passivation of silicon surfaces. Our experiments on n- and p-type silicon wafers deposited by thin Al2O3/TiO2 stacks show that a considerably improved passivation is obtained compared to the Al2O3 single layer. For Al2O3 films thinner than 20 nm the emitter saturation current density decreases with increasing TiO2 thickness. Especially the passivation of ultrathin (∼5 nm) Al2O3 is very effectively enhanced by TiO2 due to a decreased interface defect density as well as an increased fixed negative charge in the stacks. Hence, the thin Al2O3/TiO2 stacks developed in this work can be used as a passivation coating for Si-based solar cells. (© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)

The electrical characteristics of Al2O3 layers prepared by the atomic layer deposition technique using O3, H2O, and plasma O2, as oxidants are investigated through capacitance–voltage measurements of metal–insulator–semiconductor capacitors. Particular emphasis is placed on the properties of thermal annealed Al2O3 for surface passivation. Capacitance measurements at flatband voltage before and after the application of constant voltage stress in the inversion regime indicate that the charge trapping and hysteresis behavior of the capacitors are more dominant at low temperature annealing. Positive flatband voltage shifts due to negative charge tunneling are also observed under both negative and positive bias voltage polarities. The interface trap densities of O3 and plasma O2-based Al2O3 samples at 450 °C decrease by an order of magnitude with increasing annealing temperature, approaching the interface trap density levels in the 1011 eV− 1 cm− 2 range. However, H2O-based Al2O3 doesn't change considerably. The interface trap density distribution shows that H2O-based Al2O3/Si annealed over 400 °C has depassivated defects, similar to those observed in SiO2/Si interfaces. A comparison of the emitter saturation current density and the interface defect density shows that the interface density at the midgap is not so useful in predicting interface recombination after corona charging.

Boron-diffused p+/n/p+ and undiffused silicon samples with (1 0 0) and (1 1 1) orientations passivated by aluminum oxide (Al2O3) that is synthesized by atomic layer deposition (ALD) have been investigated. Emitter saturation current densities of ~24, 29, and 33 fA/cm2 were obtained for (1 0 0) samples with symmetrical 85Ω/□ B diffusions that were passivated by plasma-assisted, H2O-based, and O3-based ALD Al2O3, respectively. Compared with undiffused samples, it was found that the additional surface doping from the diffusion reduces recombination at the Al2O3/Si interface in the case of relatively low surface boron concentrations (

Passivated emitter and rear contact (PERC) is a promising technology owing to high efficiency can be achieved with p-type wafer and their easily applicable to existing lines. In case of using p-type mono wafer, 0.5–1% efficiency increase is expected with PERC technologies compared to existing Al BSF solar cells, while for multi-wafer solar cells it is 0.5–0.8%. We addressed the optimization of PERC solar cells using the Al paste. The paste was prepared from the aluminum–silicon alloy with eutectic composition to avoid the formation of voids that degrade the open-circuit voltage. The glass frit of the paste was changed to improve adhesion. Scanning electron microscopy revealed voids and local back surface field between the aluminum electrode and silicon base. We confirmed the conditions on the SiNx passivation layer for achieving higher efficiency and better adhesion for long-term stability. The cell characteristics were compared across cells containing different pastes. PERC solar cells with the Al/Si eutectic paste exhibited the efficiency of 19.6%.

We used genomic sequencing of Korean subjects to identify the uncoupling protein-1 (UCP1) polymorphism -412A>C (rs3811787 in the dbSNP database). This study is the first to associate this polymorphism with a human phenotype. The frequency of the major A allele was 0.53 and that of the minor C allele was 0.47. The -412A>C polymorphism was not linked to the well-known -3826A>G (rs1800592; ∣D’∣=0.60 and r2=0.33), yielding four predicted haplotypes from these two polymorphisms. We associated -412A>C, -3826A>G and their haplotypes with computed tomography-measured body fat areas from 367 Korean female subjects. The G allele of -3826A>G and the C allele of -412A>C were significantly associated with larger areas of abdominal subcutaneous fat in a dominant model (p=0.001 and p=0.0004, respectively); combining them together (ht2[GC]) enhanced this significance (p=0.00005). In contrast, presence of the A allele in both polymorphisms (ht1[AA]) was significantly associated with smaller areas of abdominal subcutaneous fat (p=0.003). We observed no significant associations between these UCP1 genetic polymorphisms and thigh fat areas, visceral fat areas, or blood biochemical profiles, suggesting that this polymorphism might differentially affect fat accumulation in different parts of the human body, even though further study is needed to elucidate the mechanism of it.

Recent studies have provided some clues with regard to the relationship existing between uncoupling protein 1 (UCP1) and blood pressure in animal experiments. In an attempt to determine the genetic polymorphisms that are associated with blood pressure in humans, we have analyzed genetic polymorphisms in UCP1 gene. In this study, we assessed the association between UCP1 genotypes and systolic blood pressure (SBP) and diastolic blood pressure (DBP), in a population comprised of 832 Korean female subjects, using a general linear model, which was adjusted for age and body mass index (BMI). Among 4 genetic polymorphisms and the haplotypes constructed from them, haplotype3 of UCP1, UCP1-ht3[GAGA], evidenced significant associations with SBP (p=0.005) and DBP (p=0.013). However, this haplotype was not significantly associated with obesity phenotypes, including BMI or fat mass (p>0.05), thereby suggesting that its association with blood pressure was independent of obesity phenotypes.

The purpose of this study is to estimate the effects of Ala55Val genetic polymorphism of uncoupling protein 2 on computed tomography-measured body fat area and calorie restriction-induced changes. Among 386 Korean female subjects, the AlaAla type was seen in 30.3%, the AlaVal type was seen in 47.2%, and the ValVal type was seen in 22.5%. This finding was in agreement with Hardy-Weinberg equilibrium. The frequency of the major Ala allele was 0.54, and that of the minor Val allele was 0.46, which were similar to those seen in Caucasian populations. When cross-sectional areas of fat tissues in the subjects were measured by computed tomography, it was shown that the total abdominal fat area and abdominal subcutaneous fat area were significantly smaller in the ValVal type compared with the AlaVal or AlaAla type (p=0.043 and p=0.044, respectively). The Ala55Val polymorphism had no effects on visceral fat area and thigh subcutaneous fat area. Among the 386 subjects, 236 subjects finished the 1-month calorie restriction program. The results showed that the body fat was reduced significantly less in the ValVal type compared with the other types (p=0.016), whereas the changes in lean body mass, protein, mineral, and water contents were not significantly different according to the Ala55Val polymorphism.

A permeability- and surface-energy-controllable polyurethane acrylate (PUA) mold, a "capillary-force material (CFM)" mold, is introduced for capillary-force lithography (CFL). In CFL, the surface energy and gas permeability of the mold are crucial. However, the modulation of these two main factors at a time is difficult. Here, we introduce new CFM molds in which the surface energy and permeability can be modified by controlling the degree of cross-linking of the CFM. As the degree of cross-linking of the CFM mold increases, the surface energy and air permeability decrease. The high average functionality of the mold material makes it possible to produce patterns relatively finely and rapidly due to the high rate of capillary rise and stiffness, and the low functionality allows for patterns to form on a curved surface with conformal contact. CFMs with different functionality and controllable-interfacial properties will extend the capabilities of capillary force lithography to overcome the geometric limitations of patterning on a scale below 100 nm and micro- and nanopatterning on the curved region.

With the emerging role of hematopoietic stem cells as potential gene and cell therapy vehicles, there is an increasing need for safe and effective nonviral gene delivery systems. Here, we report that gene transfer and transfection efficiency in human hematopoietic and cord blood CD34+ cells can be enhanced by the use of low molecular weight polyethylenimine (PEI). PEIs of various molecular weights (800-750,000) were tested, and our results showed that the uptake of plasmid DNA by hematopoietic TF-1 cells depended on the molecular weights and the N/P ratios. Treatment with PEI 2K (m.w. 2000) at an N/P ratio of 80/1 was most effective, increasing the uptake of plasmid DNA in TF-1 cells by 23-fold relative to Lipofectamine 2000. PEI 2K-enhanced transfection was similarly observed in hematopoietic K562, murine Sca-1+, and human cord blood CD34+ cells. Notably, in human CD34+ cells, a model gene transferred with PEI 2K showed 21,043- and 513-fold higher mRNA expression levels relative to the same construct transfected without PEI or with PEI 25 K, respectively. Moreover, PEI 2K-treated TF-1 and human CD34+ cells retained good viability. Collectively, these results indicate that PEI 2K at the optimal N/P ratio might be used to safely enhance gene delivery and transfection of hematopoietic and human CD34+ stem cells.

Although prolonged transgene expression in progenitor cells might be desirable for modified cell therapy, the viral promoter-based expression vector tends to promote transgene expression only for a limited period. Here, we examined the ability of cellular promoters from elongation factor-1alpha (EF-1alpha) and ubiquitin C to drive gene expression in hematopoietic TF-1 and mesenchymal progenitor cells. We compared the expression levels and duration of a model gene, interleukin-2, generated by the cellular promoters to those by the cytomegalovirus (CMV) promoter. The EF-1alpha and ubiquitin C promoters drove prolonged gene expression in hematopoietic TF-1 and mesenchymal progenitor cells, whereas the CMV promoter did not. At day 7 after transfection in TF-1 cells, the mRNA expression levels of interleukin-2 driven by the EF-1alpha and ubiquitin C promoters were 118- and 56-fold higher, respectively, than those driven by the CMV promoter. Similarly, in mesenchymal progenitor cells, the expression levels of interleukin-2 driven by the EF-1alpha and ubiquitin C promoters were 98- and 20-fold higher, respectively, than that driven by the CMV promoter-encoding plasmid. Moreover, the ubiquitin C promoter directed higher levels of green fluorescence protein expression in mesenchymal progenitor cells than did the CMV promoter. These results indicate that the use of cellular promoters such as those for EF-1alpha and ubiquitin C might direct prolonged gene expression in hematopoietic and mesenchymal progenitor cells.

Modulus-tunable ultraviolet (UV) curing molds allow not only physical patterning of imprinting but also chemical patterning of microcontact printing. The mechanical properties of the mold can be tailored by the chain length of an acrylate modulator in the cross-linking reaction. This tunability can be utilized to obtain a proper balance that is needed for a given patterning technique between the rigidity requirement (tensile modulus = 320 MPa) of a mold for patterning a fine structure and the flexibility requirement (tensile modulus = 19.8 MPa) for a conformal contact. Successful low-pressure imprinting of sub-100-nm patterns and microcontact printing of submicrometer patterns verify the suitability of the mold for a wide spectrum of patterning techniques.

The xeroderma pigmentosum complementation group F (XPF) protein is a structure-specific endonuclease in a complex with ERCC1 and is essential for nucleotide excision repair (NER). We report a single cDNA of Caenorhabditis elegans (C. elegans) encoding highly similar protein to human XPF and other XPF members. We propose to name the corresponding C. elegans gene xpf. Messenger RNA for C. elegans xpf is 5'-tagged with a SL2 splice leader, suggesting an operon-like expression for xpf. Using RNAi, we showed that loss of C. elegans xpf function caused hypersensitivity to ultra-violet (UV) irradiation, as observed in enhanced germ cell apoptosis and increased embryonic lethality. This study suggests that C. elegans xpf is conserved in evolution and plays a role in the repair of UV-damaged DNA in C. elegans.

A method of transferring a bilayer of polymer capped with metal to a substrate is developed with a mould that is coated with a metal followed by a polymer. A self-assembled monolayer chemisorbed on the mould surface plays a key role in the bilayer transfer. This bilayer reversal imprint lithography offers a distinct advantage over other imprint techniques in allowing for a high aspect ratio of the pattern transferred onto a substrate, which has been difficult to obtain for small feature sizes. The method requires only one etching step as opposed to the two etching steps typically needed in the imprint lithography, which can degrade the pattern fidelity.

This study reports the use of erythrocyte ghosts (EG) as a biocompatible nonviral delivery system for extended circulation and prolonged expression of plasmid DNA in the blood. Murine interleukin-2-expressing plasmid DNA was efficiently loaded to EG by electroporation in hypotonic condition. The presence of plasmid DNA in EG was confirmed by fluorescence-labeled plasmid DNA. At 21 min after intravenous administration into mice, the level of plasmid DNA in the blood was 92 000-fold higher following EG-mediated delivery as compared to the injection of naked form. EG-mediated gene delivery revealed higher and more prolonged mRNA expression levels of plasmid DNA in the blood until 9 days after the single intravenous injection. Moreover, plasmid DNA-loaded EG showed gene expression targeted to the blood cells. At 3 days post-dose, substantial expression levels of plasmid DNA delivered in EG were observed only in the blood and not in the other organs. Of the blood cells, the subpopulation containing granulocytes showed higher expression of plasmid DNA than mononuclear cells. These results indicate the potential of EG as a safe, prolonged and blood-targeted delivery system of therapeutic genes.

Complete thermodynamic binding profiles for the interaction of the anticancer drug, daunomycin with natural DNA and synthetic deoxypolynucleotides were described. Fluorescence titration method was used to estimate the equilibrium binding constants. Binding isotherms were found to be surprisingly complex in some cases, presumably because there were heterogeneous sites even in simple deoxypolynucleotides of repeating sequence. Some polynucleotides consisting of alternating sequence contain at least two different binding sites for daunomycin. The binding affinity of the primary binding sites of alternating and non-alternating sequences was found to differ by two orders of magnitude. An isothermal microtitration calorimeter was used to directly measure the binding enthalpy at 25 degrees C with a high sensitivity. The binding enthalpy of poly[d(A-T)] was found to be -5.5 Kcal/mol, which was much lower than any other polynucleotides, while the binding constant of the high affinity sites, was similar. In this report, the complete thermodynamic profiles of daunomycin binding to deoxypolynucleotides were reliably shown for the first time.

The binding mode of DNA sequence specific compounds can be established by characterizing the binding agents completely. A variety of solution studies may indirectly be used for determining the binding mode. The sequence specificity of certain DNA binding drugs has been found to be related to the specific mode of binding. In this study, only certain methods are found to be reliable to infer the binding mode of DNA binding drugs. Comparative fluorescence and hydrodynamic studies have been done. The results in this study show that most fluorescence measurements are not sensitive indicators of the mode of binding. The fluorescence intensity, fluorescence polarization, and quenching measurements can detect the binding interaction of ligands with DNA. Fluorescence contact energy transfer studies can reliably indicate the different mode of binding. These results illustrate reliable criteria that may be used to distinguish the intercalation from the groove binding. They also infer the mode of binding in the absence of high-resolution structural data.

DNA binding compounds were previously shown to bind to the right-handed DNA forms and hybrid B-Z forms in a highly cooperative manner and indicate that structural specificity plays a key role in a ligand binding to DNA. In this study, the modes of binding and structural specificity of agents to unusual DNA are examined by a variety of fluorescence techniques (intensity, polarization and quenching, etc.) to explore a reliable method to detect the association environment of ligands to deoxyoligonucleotides initially containing a B-Z junction between the left-handed Z-DNA and right-handed B-DNA. The results of fluorescence energy transfer measurement demonstrated that the ligand molecules bind to the allosterically converted DNA structures by intercalation. In the absence of high-resolution structural data, this fluorescence energy transfer measurement allowed reliable measures and infer the binding environment of ligands to the allosteric DNA structures.

The binding of the anticancer drug daunomycin to double-helical DNA has been investigated by DNase I footprinting and fluorescence titration, using a series of polymerase chain reaction (PCR) synthesized DNA fragments that contained systematic base substitutions to alter the disposition of functional groups within the minor groove. The 160 bp tyrT DNA fragment constituted the starting material. Fragments in which (i) inosine was substituted for guanosine, (ii) diaminopurine was substituted for adenine, and (iii) both inosine and diaminopurine were substituted for guanosine and adenine, respectively, were studied. These fragments permit the role of the 2-amino group in the minor groove to be systematically explored. The results of DNase I footprinting experiments confirmed that daunomycin binds preferentially to 5'(A/T)GC and 5'(A/T)CG triplets in the normal fragment. Substitution of inosine for guanosine, with the concomitant loss of the N-2 in the minor groove, weakened binding affinity but did not dramatically alter the sequence preference associated with daunomycin binding. Complete reversal of the location of the N-2 group by the double substitution, however, completely altered the sequence preference of daunomycin and shifted its binding from the canonical triplets to ones with a 5'IDD motif. These results have critically tested and confirmed the proposed key roles of the daunosamine moiety and the 9-OH group of daunomycin in dictating binding to preferred sites. In a parallel study, both macroscopic and microscopic binding to the normal tyrT fragment were investigated, experiments made possible by using PCR to prepare large quantities of the long, defined DNA sequence. The results of these experiments underscored the complexity of the interaction of the drug with the DNA lattice and revealed unequivocal heterogeneity in its affinity for different binding sites. A class of high-affinity sites, most probably corresponding to the 5'(A/T)GC and 5'(A/T)CG triplets, was identified and characterized in macroscopic binding isotherms.

A detailed study of the passivation quality of Al2O3 and TiO2 stacks on boron-doped emitters, where the stacks were deposited by thermal atomic layer deposition. The passivation quality was studied for different post-TiO2 anneal temperature, as a function of Al2O3 and TiO2 layer thickness. For annealed Al2O3 layers, as-deposited TiO2 capping layer decreased emitter saturation current density considerably, which was more significant on Al2O3 with thickness below 10 nm. However, post-TiO2 deposition anneal in O2 environment degraded the passivation, which was attributed to the increasing interface trap density in spite of increasing effective fixed charge density.

The effect of humidity on boron diffused and undiffused silicon samples passivated by aluminum oxide (Al 2 O 3 ) synthesized by plasma-assisted atomic layer deposition (PA-ALD) has been investigated. We found that undiffused samples show a higher degradation rate than diffused samples. Under an ambient of 100% relative humidity and 50°C, the lifetime of an undiffused sample passivated by Al 2 O 3 decreased from 1500 to 400μs after 28 hours of exposure, whereas the saturation current density of the diffused region J op+ of a boron diffused sample was nearly unchanged after 7 days of exposure. As expected, for both diffused and undiffused samples, the degradation rate is accelerated by increasing the temperature of the humidity environment. A PECVD SiN x , capping layer acts as an effective protection layer for Al 2 O 3 to resist a damp-heat conditions of 100% relatively humidity at 80°C. The electrical resistance of PA-ALD Al 2 O 3 was observed to degrade in humidity. Fourier Transform Infra-red Spectroscopy (FTIR) measurements indicate that damp heat results in a structural modification of the bulk Al 2 O 3 film and the formation of AlO(OH). This change could be responsible for the fast degradation rate of PA-ALD Al 2 O 3 passivation compared with SiO 2 . Finally, we experimentally demonstrated that the degraded passivation of an Al 2 O 3 layer can be repaired by light illumination and negative corona charge deposition.

Fluorescence and absorption spectroscopy, isothermal titration calorimetry, and viscosity measurements have been used to characterize the interaction of Delta and Lambda [Ru(phen)(2)DPPZ](2+) with calf thymus DNA. The method of continuous variations revealed two distinct binding stoichiometries for both Delta- and Lambda-DPPZ, corresponding to 0.7 and 3 mol of base pair/mol of ligand. Binding isotherms were obtained for the two enantiomers, both of which show strong binding to DNA, with K = 3.2 x 10(6) M(-1) bp and 1.7 x 10(6) M(-1) bp for the Delta and Lambda isomers, respectively, at 25 degrees C in solutions containing 50 mM NaCl. Titration calorimetry gave Delta H values of +0.3 kcal mol(-1) for Delta-DPPZ and +2.9 kcal mol(-1) for Lambda-DPPZ for their interaction with DNA. These small positive enthalpies, which were confirmed using thermal difference spectroscopy, indicated that the binding of these compounds to DNA is entropically driven. An enthalpy of +2.5 kcal mol(-1) was obtained for the binding of the parent compound, tris(phenanthroline)-Ru(II), to DNA. Titration of all three compounds into buffer gave a nonnegligible heat of dilution. The salt dependence of the binding constant was examined for both isomers. The slope SK = (delta logK/delta log[Na+]) was found to be 1.9 and 2.1 for the Delta and Lambda isomers, respectively. By using polyelectrolyte theory to interpret the observed salt dependence of the equilibrium constant, it can be shown that there is a significant nonelectrostatic contribution to the binding constant. Relative viscosity experiments showed that both Delta- and Lambda-DPPZ increase the length of rod-like DNA, in a manner consistent with binding by classical intercalation. Fluorescence energy transfer experiments provided additional evidence for the intercalation of Delta- and Lambda-[Ru(phen)(2)DPPZ](2+) into DNA.

The NaCl-induced transition from the right-handed B form to a hybrid form containing both left and right-handed DNA, joined by a B-Z junction, was investigated. Transition curves were constructed from circular dichroism spectra collected as a function of NaCl concentration for a series of 16 bp deoxyoligonucleotides. The sequence of the series (one strand of the duplex) was: 5′ CGCGCGCGAMNGACTG, where C indicates m 5 dc, and -MN- was varied to include the possible Py: Py stacks: -CC-, -CT-, -TC- and -TT-, Transition curves for the conversion of all deoxyoligonucleotides were found to be biphasic. Singular value decomposition was used to analyze the experimental circular dichroism spectra obtained as a function of NaCl, and showed that the transition was not a simple two-state process, but rather required at least three species to account for the experimental data. A sequential three-state model, B⇌1⇌BZ, was derived and applied to analyze experimental transition curves. Non-linear least-squares analysis was used to evaluate the salt-dependent equilibrium constants for each step in the sequential reaction model. The results indicate that the free energy change for B-Z junction formation (ΔG j ) depends on the dinucleotide sequence near the junction. At a Na activity of 5, ΔG j , values ranging from +1·2 to +1·7 kcal mol -1 were determined, depending on the sequence near the junction. ΔG j was found to be strongly dependent on salt concentration, with its magnitude decreasing with increasing Na activity. In addition to studies on linear duplex molecules, the B to BZ transition was also investigated in "dumbbell" forms of selected sequences. In these molecules, the ends were covalently linked by a single-stranded T 4 segment. These studies show that junction formation is energetically more costly in dumbbells than in their linear counterparts. A striking correlation was found between ΔG j and two independent conformational properties of the dinucleotide steps that were introduced into the linear duplex molecules. These are the free energy of unstacking and the estimated free energy change for the conversion of the dinucleotide from the B to the A conformation. The more stable against unstacking, or the more resistant to the B to A conversion, the sequence near the junction site is, the more costly is B-Z junction formation. These correlations reveal that the DNA sequence near the junction apparently must be pliable in order to accommodate the unusual structure of the junction. Thus, junction formation must directly affect, if only in subtle ways, the conformation of the neighboring right-handed region.

Equilibrium binding studies are reported that describe the interaction of the simple intercalator ethidium with a hexadecadeoxynucleotide (BZ-1) that contains a stable B-Z junction. The transition of BZ-1 from its low-salt right-handed form to its high-salt hybrid form containing the junction between left- and right-handed DNA was found to greatly facilitate ethidium binding. Ethidium binding to all conformational forms of BZ-1 was found to be complex and highly cooperative, a result that indicates an unusually robust conformational mobility in the molecule. Binding results were quantitatively analyzed by using an allosteric model that provides a description of energetics of the conformational transitions in BZ-1, in addition to estimates of the binding constants for ethidium binding to the different conformations. These results provide a quantitative description of a structurally specific intercalator-DNA interaction.

We used genomic sequencing of Korean subjects to identify the uncoupling protein-1 (UCP1) polymorphism -412AC (rs3811787 in the dbSNP database). This study is the first to associate this polymorphism with a human phenotype. The frequency of the major A allele was 0.53 and that of the minor C allele was 0.47. The -412AC polymorphism was not linked to the well-known -3826AG (rs1800592; mid R:D'mid R:=0.60 and r(2)=0.33), yielding four predicted haplotypes from these two polymorphisms. We associated -412AC, -3826AG and their haplotypes with computed tomography-measured body fat areas from 367 Korean female subjects. The G allele of -3826AG and the C allele of -412AC were significantly associated with larger areas of abdominal subcutaneous fat in a dominant model (p=0.001 and p=0.0004, respectively); combining them together (ht2[GC]) enhanced this significance (p=0.00005). In contrast, presence of the A allele in both polymorphisms (ht1[AA]) was significantly associated with smaller areas of abdominal subcutaneous fat (p=0.003). We observed no significant associations between these UCP1 genetic polymorphisms and thigh fat areas, visceral fat areas, or blood biochemical profiles, suggesting that this polymorphism might differentially affect fat accumulation in different parts of the human body, even though further study is needed to elucidate the mechanism of it.

The purpose of this study is to estimate the effects of Ala55Val genetic polymorphism of uncoupling protein 2 on computed tomography-measured body fat area and calorie restriction-induced changes. Among 386 Korean female subjects, the AlaAla type was seen in 30.3%, the AlaVal type was seen in 47.2%, and the ValVal type was seen in 22.5%. This finding was in agreement with Hardy-Weinberg equilibrium. The frequency of the major Ala allele was 0.54, and that of the minor Val allele was 0.46, which were similar to those seen in Caucasian populations. When cross-sectional areas of fat tissues in the subjects were measured by computed tomography, it was shown that the total abdominal fat area and abdominal subcutaneous fat area were significantly smaller in the ValVal type compared with the AlaVal or AlaAla type (p=0.043 and p=0.044, respectively). The Ala55Val polymorphism had no effects on visceral fat area and thigh subcutaneous fat area. Among the 386 subjects, 236 subjects finished the 1-month calorie restriction program. The results showed that the body fat was reduced significantly less in the ValVal type compared with the other types (p=0.016), whereas the changes in lean body mass, protein, mineral, and water contents were not significantly different according to the Ala55Val polymorphism.

Telomeres are the ends of the linear chromosomes of eukaryotes and consist of tandem GT-rich repeats in telomere sequence i.e. 500-3000 repeats of 5'-TTAGGG-3' in human somatic cells, which are shortened gradually with age. The G-rich overhang of telomere sequence can adopt different intramolecular fold-backs and tetra-stranded DNA structures, in vitro, which inhibit telomerase activity. In this report, DNA binding agents to telomere sequence were studied novel therapeutic possibility to destabilize telomeric DNA sequences. Oligonucleotides containing the guanine repeats in human telomere sequence were synthesized and used for screening potential antitumor drugs. Telomeric DNA sequence was characterized using spectral measurements and CD spectroscopy. CD spectrum indicated that the double-stranded telomeric DNA is in a right-handed conformation. Polyacrylamide gel electrophoresis was performed for binding behaviors of antitumor compounds with telomeric DNA sequence. Drugs interacted with DNA sequence caused changes in the electrophoretic mobility and band intensity of the gels. Depending on the binding mode of the anticancer drugs, telomeric DNA sequence was differently recognized and the efficiency of cleavage of DNA varies in the bleomycin-treated samples under different conditions. DNA cleavage occurred at about 1% by the increments of 1 micromM bleomycin-Fe(III). These results imply that the stability of human telomere sequence is important in conjunction with the cancer treatment and aging process.