Electrical transport properties of graphene-covered-Cu wires grown by chemical vapor deposition

We investigated the field-effect transistor (FET) characteristics of 15-μm graphene-covered copper wires (G-wires). Unlike the previously reported graphene FET, carries initially showed p-type like FET characteristics in two-terminal transport measurements. Our results indicate that the electrical transport processes in a G-wire FET occur in both the heavily p-doped contact and the p-doped radial graphene channel, as a p-channel. The interfacial potential barrier between the contact electrode and the radial graphene channel is small, but there is a radial potential barrier that limits electrical transport through the copper core in chemical vapor deposition (CVD) grown samples. The p-type FET characteristics appeared clearly after the oxidation of the G-wires.     

Zincon as resonance Raman probe for quantitative evaluation of proteins

This paper demonstrates the potential of using a resonance Raman (RR) based method for the quantitative evaluation of protein concentrations. This method was applied to determine the concentration of bovine serum albumin (BSA) protein using zincon. In the protein–zincon liquid mixture, the number of unbound zincon molecules decreased markedly as the protein concentration increased because of the high affinity of zincon for proteins. We successfully detected very low concentrations of BSA (∼1 ng/ml) using this method, which demonstrates its great potential for the detection of proteins over a much wider range of concentrations in proteomic studies. This new RR‐based method allows the detection of proteins in lower concentration than with the UV–vis‐based and other protein assays commonly used in biochemical laboratories. Copyright © 2011 John Wiley & Sons, Ltd.     

Multifunctional Conjugated Polymers with Main‐Chain Donors and Side‐Chain Acceptors for Dye Sensitized Solar Cells (DSSCs) and Organic Photovoltaic Cells (OPVs)

A novel multifunctional conjugated polymer (RCP‐1) composed of an electron‐donating backbone (carbazole) and an electron‐accepting side chain (cyanoacetic acid) connected through conjugated vinylene and terthiophene has been synthesized and tested as a photosensitizer in two major molecule‐based solar cells, namely dye sensitized solar cells (DSSCs) and organic photovoltaic cells (OPVs). Promising initial results on overall power conversion efficiencies of 4.11% and 1.04% are obtained from the basic structure of DSSCs and OPVs based on RCP‐1, respectively. The well‐defined donor (D)‐acceptor (A) structure of RCP‐1 has made it possible, for the first time, to reach over 4% of power conversion efficiency in DSSCs with an organic polymer sensitizer and good operation stability.     

Tooth Distortion as a Function of Arch Form in Cone Beam Computed Tomography

The cone beam computed tomography enables conducting measurement of length and area in the space where it is impossible to conduct such measurement compared to panorama. The cone beam computed tomography also enables making three-dimensional diagnosis and establishing treatment plan. In this experiment, the cone beam computed tomography was used to analyze image distortion of anatomical structure whose location was different between panorama and reconstructed panoramic image. Multiplanar reformation image was obtained after radiography of mandibular dentition. Then, the axial image was examined to obtain cross-sectional images of teeth that ranged from the right second molar to the left second molar before diameter of crown was measured and compared. Based on the cross-section that was radiographed by using the cone beam computed tomography, comparison was made between reconstructed panorama and standard panorama. According to the results of comparison, diameter of crown was measured with a slight difference of around 0.03 mm between the cone beam computed tomography cross-sectional image and the reconstructed image. It was also found that panorama caused image distortion with the large error of around 0.95 mm. Based on these results, it was confirmed that the cone beam computed tomography panorama that was reconstructed in consideration of patient's anatomical structure showed less distortion than the existing panorama. It was also confirmed that depending on distance, there was decrease in reliability of measurement of anatomical structure whose location was different in the existing panoramic image. It is necessary to develop methods and various programs in the future to improve poor image information that is obtained from the cone beam computed tomography and panorama examination.     

O-Atom Exchange between H(2)O and CO(2) Mediated by a Bis(dithiolene)tungsten Complex

Inspired by the CO(2)-reductatse activity of tungsten-dependent formate dehydrogenases (W-FDHs), a reduced W-FDH model, [W(IV)(OH)(S(2)C(2)Ph(2))(2)](-), was prepared in situ through hydrolysis of [W(IV)(OPh)(S(2)C(2)Ph(2))(2)](-) (1) and its reactivity with CO(2) was investigated. The reaction between [W(IV)(OH)(S(2)C(2)Ph(2))(2)](-) and CO(2) at room temperature leads to the formation of [W(IV)(O)(S(2)C(2)Ph(2))(2)](2-) (2), which slowly oxidizes to [W(V)(O)(S(2)C(2)Ph(2))(2)](-) (3). Isotopic labeling experiments reveal that the O atom in CO(2) incorporates into 3. This implies that there is carbonic anhydrase like activity, in which carbonation and decarboxylation are mediated by a bis(dithiolene)tungsten complex.     

Effect of nano-filler dispersion on the thermal, mechanical and water sorption properties of green environmental polymer

Partially exfoliated nanocomposite（2） has been synthesized by intercalation of poly（propylene carbonate）（PPC） into commercial clay,Cloisite 20B（PPC/C-20B）.Nanocomposite 2 was characterized phiso-chemically and exhibited high thermal,mechanical and anti-water sorption properties as compared to PPC and intercalated nanocomposite（1） of PPC/C-20B having same amount of clay.TGA results revealed that the thermal decomposition temperature(T_d,50%) of 2 increased significantly,being 40 K and 17 K higher than that of pure PPC and 1,respectively,while DSC measurements indicated that the nano-filler dispersion of 2 increased the glass transition temperature from 21℃to 31℃.Accordingly,2 showed high elastic modulus,hardness and anti-water absorption capacity.These thermal,mechanical and anti-water absorption improvements are of great importance for the application of PPC as packaging and biomaterials.     

Flavonoid profiling in three citrus varieties native to the Republic of Korea using liquid chromatography coupled with tandem mass spectrometry: contribution to overall antioxidant activity

A mixture of flavonoid components was isolated from the fruit peel of three varieties of citrus native to Republic of Korea, Citrus leiocarpa Hort. ex Tanaka (CLHT), Citrus aurantium L. (CAL) and Citrus erythrosa Hort. (CEH), via 70% methanol extraction followed by ethyl acetate elution over a silica gel cartridge. The flavonoid components of the mixture were analyzed via high‐performance liquid chromatography–tandem mass spectrometry (HPLC‐MS/MS) in positive‐ion mode and a comparison of the reported data. Among 17 characterized components, two flavanones, four flavones and two coumarin derivatives in the fruit peel of the three varieties were identified for the first time. The individual characterized components were quantified via HPLC‐UV. The flavanones dominated in CAL, whereas the flavones prevailed in CLHT and CEH. The antioxidant activity of the flavonoid mixture of the fruit peel was determined via DPPH^?, ABTS^?+ and reducing power assays. The antioxidant activity of CEH and CAL was greater than that of CLHT. Copyright © 2011 John Wiley & Sons, Ltd.     

Build-up of symmetry breaking using a titanium suboxide in bulk-heterojunction solar cells

The importance of symmetry breaking was investigated in bulk heterojunction solar cells with a conventional device structure. Artificial symmetry breaking was built up by introducing a titanium suboxide. With sufficient symmetry breaking, the influence of the cathode work-function can be diminished, thereby extracting the same level of open circuit voltage regardless of metal work-function.     

Synthesis of Highly n-Type Graphene by Using an Ionic Liquid

n-Type graphene: A new, easy, and cheap method to produce n-type reduced graphene oxide was developed by synthesizing a partially reduced intermediate containing nitrogen (PrGO-IL, see scheme) by treating graphene oxide (GO) with an ionic liquid (IL) at 160?°C followed by rapid thermal annealing (RTA) at temperatures ranging from 400 to 1000?°C. A high N-doping level of 6?% was achieved and the N-doped rGO exhibits n-type behavior with a Dirac point at -38?V at 400?°C.     

Can commonly used hydrazine produce n-type graphene?

A simple chemical method to obtain bulk quantities of N-doped, reduced graphene oxide (rGO) sheets (see figure) as an n-type semiconductor through the treatment of as-prepared GO sheets with the commonly used reducing reagent hydrazine, followed by rapid thermal annealing (RTA) is described.