Single molecular switch based on thiol tethered iron(II)clathrochelate on gold

Molecular electronics has been associated with high density nano-electronic devices. Developments of molecular electronic devices were based on reversible switching of molecules between the two conductive states. In this paper, self-assembled monolayers of dodecanethiol (DDT) and thiol tethered iron(II)clathrochelate (IC) have been prepared on gold film. The electrochemical and electronic properties of IC molecules inserted into the dodecanethiol monolayer (IC-DDT SAM) were investigated using voltammetric, electrochemical impedance spectrpscopy (EIS), scanning tunneling microscopy (STM) and cross-wire tunneling measurements. The voltage triggered switching behaviour of IC molecules on mixed SAM was demonstrated. Deposition of polyaniline on the redox sites of IC-DDT SAM using electrochemical polymerization of aniline was performed in order to confirm that this monolayer acts as nano-patterned semiconducting electrode surface.     

HEAT EFFECTS FOR PHYSICAL AND CHEMICAL ABSORPTION IN TURBULENT LIQUID FILMS

An eddy diffusivity model was used to describe simultaneous heat and mass transfer for chemical absorption in turbulent liquid films. For absorption accompanied by a first-order reaction an approximate expression for the mass transfer coefficient is derived and shown to be in excellent agreement with exact numerical calculations. An equation is developed for the temperature rise at the free surface due to both the heat of reaction and the heat of solution. Relationships are also developed for the concentration of the liquid phase product at the free surface and the depletion of the liquid phase reactant at the free surface.

The temperature rise at the free surface for gas absorption accompanied by an instantaneous reaction due to both the heat of solution and the heat of reaction was determined. An equation is also derived for the concentration of liquid phase product at the free surface for the case of an instantaneous reaction.     

Diode pumped operation of thulium doped fluoride fibre amplifiersuitable for first window systems

A fully connectorised diode laser pumped first window amplifier has been constructed, for the first time, around a thulium doped fluoride fibre. For a 780/806 nm combination of pump and signal wavelengths, small signal gains of 25-26 dB and gain efficiencies of 2.4 dB/mW have been achieved. In addition, output powers approaching +13 dBm are possible for a launched pump power of 31 mW, which corresponds to a conversion efficiency of around 650%     

Overexpression and large-scale purification of recombinant hamster polymorphic arylamine N-acetyltransferase as a dihydrofolate reductase fusion protein

N-Acetyltransferases (NATs) are enzymes that catalyze the detoxification and/or bioactivation of a variety of xenobiotics. Rapid kinetic, biophysical, structural, and bioactivation studies on NATs require quantities of purified enzyme capable of being obtained only through recombinant DNA technology. This laboratory has previously developed a protein expression and purification system in which NATs are expressed as proteins fused to a FLAG octapeptide followed by a thrombin-cleavage site to allow liberation of the rNAT. Typically, however, only 0.5-1.5 mg of the recombinant NAT's could be readily purified in a single isolation sequence by immunoaffinity chromatography. Therefore, the expression system was modified by inserting the L54F dihydrofolate reductase (DHFR) mutant gene sequence between the FLAG octapeptide and the thrombin-cleavage site. Expression was carried out with TOPP3 Escherichia coli cells. The new purification methodology utilizes the unique pH dependence of binding to a methotrexate (MTX)-affinity column by the L54F DHFR mutant. Unfortunately, the affinity chromatography strategy did not work satisfactorily. Although the specific activity of the purified rNAT2 was comparable to that of NAT2 obtained from hamster tissue, only 3% of the activity was recovered. The apparent cause of the low recovery is the unanticipated irreversible binding of rNAT2 to MTX. Ion-exchange chromatography was investigated as an alternative purification method. An initial DEAE anion-exchange column resulted in partial purification of the fusion protein. The fusion protein was cleaved with thrombin and reapplied to a DEAE anion-exchange column. The second DEAE column resulted in not only the separation of rNAT2-70D from FLAG-L54F DHFR, but also the purification of rNAT2-70D to near homogeneity. Application of the nearly homogeneous rNAT2-70D to a gel-filtration column resulted in recovery of homogeneous protein. The ion-exchange method of purifying rNAT2-70D is inexpensive and simple and yields more than 8 mg of pure enzyme from 1 liter of cell culture.     

Effect of curing conditions on the total water content of hardened portland cement paste

The effect of various curing conditions on the amount of water held by pastes with low water/cement ratios was investigated. It was concluded from the results that factors significantly influencing the total water content of a cement paste made with ordinary Portland cement and cured at room temperature are: water/cement ratio, curing medium, curing period and curing history.     

An advanced start algorithm for all-integer programming

In this paper, we present an all-integer cutting plane technique called the Advanced Start Algorithm (ASA), for solving the all-integer (otherwise linear) programming problem (IP). We develop a good advanced primal-infeasible start based on the optimal solution to the LP relaxation, and use a two-stage dual/primal algorithm to obtain the optimal solution to (IP). We illustrate the operation of the ASA on three small problems, and exhibit computational results on a set of standard test problems.     

Effect of moisture content of raw materials on the viscosity of limestone–marl slurry

Viscosity measurements were performed to investigate the effect of moisture contained in Portland cement raw materials on the flow characteristics of limestonemarl slurry. Under conditions of constant total water content, the fluidity of the slurry increased as the moisture content of the raw materials decreased. The effect of moisture content of the raw materials becomes significant on reducing the water content of the slurry. In the presence of slurry thinners, the extent of deflocculation is greater with the raw materials of lower moisture content.     

Uncertainty orientation and trust in close relationships: Individual differences in cognitive styles.

Because coping with uncertainty is an important aspect of close relationships and is critical to issues of trust, the authors expected individual differences in uncertainty orientation to play a central role in shaping people's representations of their relationships. For a 3-week period, 77 couples completed a series of questionnaires and kept diaries on their interactions. As expected, certainty-oriented persons' need for cognitive closure resulted in either high or low trust for their partners, whereas uncertainty-oriented persons typically attained only a moderate level of trust. Several other measures indicated that certainty-oriented partners found their relationships most aversive under moderate trust. Memory data indicated that certainty-oriented individuals, but not uncertainty-oriented individuals, used conclusions about trust as a heuristic for reconstructing the past in ways that maintained cognitive clarity. Uncertainty orientation also combined with gender in many interesting ways. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Die unterschiedliche Zähigkeit verschieden wärmebehandelter hochfester Stähle gleicher Zugfestigkeit am Beispiel des Vergütungsstahls 50 CrMo 4

Erzeugung von vier Gefügen mit gleicher Zugfestigkeit von rd. 1200 MPa durch geeignete Wärmebehandlungen. Differenzierung der Gefüge durch die Brucheinschnürung bei 77 K und die Bruchzähigkeit bei 173 K. Zusammenhang der Zähigkeitswerte mit dem raster-elektronenmikroskopisch festgestellten Bruchflächenaussehen und mit den elektronenmikroskopisch festgestellten Anordnungen der Versetzungen und Ausscheidungen. Folgerungen für eine günstige Zähigkeit bei hoher Streckgrenze und hohem Streckgrenzenverhältnis.