Chemical-Labeling-Assisted Detection of Nucleobase Modifications by Quantum-Tunneling-Based Single-Molecule Sensing

Quantum-tunneling-based DNA sensing is a single-molecule technique that promises direct mapping of nucleobase modifications. However, its applicability is seriously limited because of the small difference in conductivity between modified and unmodified nucleobases. Herein, a chemical labeling strategy is presented that facilitates the detection of modified nucleotides by quantum tunneling. We used 5-Formyl-2′-deoxyuridine as a model compound and demonstrated that chemical labeling dramatically alters its molecular conductance compared with that of canonical nucleotides; thus, facilitating statistical discrimination, which is impeded in the unlabeled state. This work introduces a chemical strategy that overcomes the intrinsic difficulty in quantum-tunneling-based modification analysis—the similarity of the molecular conductance of the nucleobases of interest.     

The quadratic finite element thermal analysis of silicon irradiated by a pulsed KrF excimer laser

The melting and solidification process of crystalline silicon (c-Si) sample flashed by a pulsed KrF excimer laser is studied numerically. The dynamics of pulsed nanosecond laser melting process is simulated by the solution of the one-dimensional heat conduction equation. The quadratic finite element method (FEM) is applied to solve the equation. This method is based upon a higher order FEM with a smaller error and allowing faster convergence to the exact solution. The surface temperatures obtained by the quadratic FEM are in good agreement with the exact solutions. In addition to this, the temperature-dependent optical and thermal properties of the irradiated c-Si have been taken into account and the calculated results are compared with the experimental data published.     

α‐Complementation in an Artificial Genome Replication System in Liposomes

Genome size is considered one of the limiting factors for the replication of primitive life forms. However, the relationship between genome size and replication efficiency has not been tested experimentally. In this study, we examined the effect of genome size on genome replication by using an artificial cell model: a self‐replicating RNA genome encapsulated in a liposome. For the reduced genome size we used α‐complementation of the lacZ gene. We first characterized α‐complementation in the purified translation system and then applied α‐complementation to the genome replication system. The reduction in the genome size together with the addition of ω‐fragment increased the replication efficiency approximately eightfold. This result provides experimental evidence that genome size can be a limiting factor for primitive self‐replication systems; it also implies that this artificial cell model could be a useful experimental model to identify possible mechanisms of genome enlargement.     

The Behavior of the Centrally Pivoted Thrust Bearing Pad with Hydrostatic Recesses Pressurized by a Constant-Rate Flow

The tilting behavior of the centrally pivoted, externally pressurized tilting thrust pad is investigated. The pressure distribution in the oil film is obtained by solving the Reynolds' equation which takes into account the external pressurization induced by a constant-rate flow. The relation between the size of the hydrostatic recess and the tilt angle of the pad is described. Calculations show that a pad with pressure recesses may have a negative tilt angle, depending on the size of the recess. The pressure variation around the hydrostatic pressure recess causes the moment to force the pad to tilt backward. At high shaft rotational speeds, the pad tilts backward too much and eventually fails to support the load. The hydrostatic pressure recess that is utilized to avoid the metal contact may cause this. The result was confirmed by experiments.     

Radical polimerization of methyl α-crotonyloxymethyl) acrylate to soluble polymer bearing pendant double bonds

Methyl α-(crotonyloxymethyl)acrylate (MCRMA) of which the α-substituted acryloyl and crotonyl groups are sterically hindered and reluctant to homopolymerize, respectively, was synthesized and polymerized. The polymerization of MCRMA primarily took place through homopolymerization of the α-(substituted methyl)acryloyl group to yield a soluble polymer bearing a large number of the pendant crotonyloxy groups. The ratio of the rate constants for the inter- and intramolecular additions of the propagating radical to form the linear and cyclic repeating units, respectively, indicates that this monomer exhibits an exceptionally low possibility of cyclopolymerization because of the sterically hindered intramolecular addition of the crotonyloxymethyloyl radical to the crotonyl group. Crosslinking by the reaction of the pendant double bond slowly proceeded due to an extremely low reactivity of the crotonyloxy group towards poly-[α-(crotonyloxymethyl)acrylate] radical. Received: 1 October 1999/Accepted: 2 November 1999     

Thermodynamic Behavior of Stable Carbon Isotopic Compositions of Individual Polycyclic Aromatic Hydrocarbons Derived from Automobiles

Concentrations, molecular compositions, and compound-specific stable carbon isotopic compositions ( i 13 C) of polycyclic aromatic hydrocarbons (PAHs) in gasoline exhaust particles (GEPs) and diesel exhaust particles (DEPs) were investigated in this study. i 13 C of PAHs in GEPs ranged from m 13.3 to m 26.8, and that in DEPs ranged from m 21.7 to m 26.3. The interspecies i 13 C variations in each sample were 5.3 - 2.2 in GEPs and 2.6 - 1.3 in DEPs. PAHs in GEPs show larger interspecies i 13 C variation than those in DEPs; hence, a degree of carbon isotopic fractionation during the conversion from fuel to PAH seems to be larger in gasoline engines than that in diesel engines. Pyrene series PAHs, which consist of only hexagonal rings, in almost all GEP samples show strong negative correlation between the H/C ratio and i 13 C whereas fluoranthene series PAHs, which contain a pentagonal ring, show less systematic isotopic behavior in GEP samples. A kinetic isotope effect in thermal cracking of organic macromolecules may be minor for PAH formation in vehicle engines. We suggest that the isotopic trend of pyrene series in GEPs can be explained by a thermodynamic isotope effect, and that disturbance from isotopic equilibrium may cause a weak correlation between the isotopic behavior and the H/C ratio among the interspecies PAHs.     

Fast redox of composite electrode of nitroxide radical polymer and carbon with polyacrylate binder

For organic radical batteries, poly(2,2,6,6-tetramethylpiperidinyloxy-4-yl methacrylate) (PTMA) has been reported as a promising positive electrode material. The PTMA/C composite electrode prepared with polyacrylate binder demonstrated the fast redox performance for the application to aprotic secondary batteries. When the variation in discharge capacities of the PTMA/C composite electrode was tested galvanostatically at 20C rates, the electrode retained 96% of the initial capacity after 1000 cycles. This is attributed to the fact that the redox of PTMA is a simple reaction to form the oxoammonium salt doped with ClO₄^? anions in the electrolyte. When the PTMA/C composite electrode was discharged at different C rates, the electrode retained 81% of the theoretical capacity even at 50C rates. This remarkably high rate capability originates from the fast electron-transfer kinetic of the 2,2,6,6-tetramethylpiperidine-N-oxyl (so-called TEMPO) radical, partially jelled polyacrylate binder, and the improved conductivity throughout the electrode by thoroughly mixing with carbon.     

Direct ortho‐Hydroxylation of 2‐Phenylpyridines using Palladium(II) Chloride and Hydrogen Peroxide

Direct functionalization of the ubiquitous C H bond is receiving much attention because complex structures can be formed from simple precursors. This paper reports a useful method for the direct hydroxylation of 2‐phenylpyridines using palladium(II) chloride and aqueous hydrogen peroxide. In this method, hydrogen peroxide, which has high atom efficiency, is employed as the oxidant and phenol derivatives are generated via C H activation.

     

Simulation results of a hexahedron-octahedron based spherical stepping motor

The simulation results of a novel stepping motor based on a pair of a regular hexahedron and a regular octahedron (call “6-8 spherical stepping motor” afterward) are presented. The 3D electromagnet and motion coupled simulation program “Magnet 6” is used for the simulation. As the conditions of simulation, the excitation current and frequency is 1 A and 5.3 Hz, respectively. Three phase sinusoidal excitation currents are applied to two pairs of three coils of the stator individually at 120 deg intervals. The simulation results show that the rotor rotates along the rotating magnetic field and the output torque is 0.04 Nm. The simulation results prove the correctness of the 6–8 spherical motor driving method. The developed 6–8 spherical stepping motor is air-core type without back yoke for avoiding the cogging torque. When using iron core with back yoke, the proposed motor will be a high-torque spherical motor. The 6–8 spherical stepping motor was tested and the experimental results were compared with the simulation results. Then, the simulation program was used for optimum design of the 6–8 spherical stepping motor.     

A comparative study on co-combustion performance of municipal solid waste and Indonesian coal with high ash Indian coal: A thermogravimetric analysis

In recent years there has been an increasing utilization of coal blends in the Indian power industry, with Indonesian coal, due to high ash content and shortages in domestic coal production. On the other hand, rapid economic growth is aggravating the municipal solid waste (MSW) related environmental problems. In this study, an attempt has been made to compare the co-combustion characteristics of hydrothermally treated MSW and Indonesian coal with high ash Indian coal, so as to replace the Indonesian coal with MSW. The effect of blending Indonesian coal and hydrothermally treated MSW with Indian coal on ignition behavior was studied. MSW blends of 10%, 20%, 30% and 50% (in wt.%), and an Indonesian blend of 10% with Indian coal were tested in a thermogravimetric analyzer (TGA) in the temperature from ambient to 700 °C with a temperature increase of 10 °C/min. From the results, at 10% of blend, ignition and carbon burnout were similar for Indonesian and MSW blend, analogous to coal combustion and even better than the Indonesian coal blend, which indicated the feasibility for replacing Indonesian coal with hydrothermally treated MSW. Further, the results show a scope to increase the MSW blend in Indian coal up to 20%, as the constituents behave as a single fuel.