Absorption Cross Sections and Kinetics of Formation of AlO at 298 K

The rate coefficient of the Al + O2 reaction has been measured in a laser ablation-fast flow tube apparatus by monitoring atomic Al resonance absorption and AlO laser induced fluorescence (LIF). The rate constant has been found to be k(298 K) = (1.68 ± 0.24) × 10-10 cm3 molecule-1 s-1. Under conditions of near-stoichiometric conversion of Al into AlO, the absorption cross section of AlO at the bandhead of the B2Σ+(v'=0)←X2Σ+(v''=0) transition has been determined to be σ(298 K, 1 hPa) = (6.7 ± 1.6) × 10-15 cm2 molecule-1 (0.003 nm resolution), in very good agreement with theoretical predictions

A highly selective, label-free, homogenous luminescent switch-on probe for the detection of nanomolar transcription factor NF-kappaB

Transcription factors are involved in a number of important cellular processes. The transcription factor NF-κB has been linked with a number of cancers, autoimmune and inflammatory diseases. As a result, monitoring transcription factors potentially represents a means for the early detection and prevention of diseases. Most methods for transcription factor detection tend to be tedious and laborious and involve complicated sample preparation, and are not practical for routine detection. We describe herein the first label-free luminescence switch-on detection method for transcription factor activity using Exonuclease III and a luminescent ruthenium complex, [Ru(phen)2(dppz)]2+. As a proof of concept for this novel assay, we have designed a double-stranded DNA sequence bearing two NF-κB binding sites. The results show that the luminescence response was proportional to the concentration of the NF-κB subunit p50 present in the sample within a wide concentration range, with a nanomolar detection limit. In the presence of a known NF-κB inhibitor, oridonin, a reduction in the luminescence response of the ruthenium complex was observed. The reduced luminescence response of the ruthenium complex in the presence of small molecule inhibitors allows the assay to be applied to the high-throughput screening of chemical libraries to identify new antagonists of transcription factor DNA binding activity. This will allow the rapid and low cost identification and development of novel scaffolds for the treatment of diseases caused by the deregulation of transcription factor activity

Handover Optimization in GSM

In telecommunications in general and in GSM in particular, the handover is a feature that guarantees a smooth transition of a call from one base station - that is for the purpose of this project an antenna - to another. In the recent ten years, the amount of data traffic through mobile telecommunications has doubled annually, putting an enormous strain on the network and forcing operators to upgrade with more and more base stations and new features. Although 3G and 4G are responsible for data traffic in most countries, GSM still provides more than 80% of the coverage for mobile devices around the world. Due to the increase in data traffic, 3G and 4G need to use more and more frequencies at the expense of GSM. An optimization of the GSM network is thus vital. In this project, we research two methods to automatically choose the parameters of interest (PoI) that govern the handover feature in each cell which is, roughly speaking, the area of coverage of one antenna. In one of these methods, the choice of cell- and cell-to-cell-specific parameters has its origins in control theory while the other method is based on mathematical optimization. In the mathematical sense, our goal is to optimize the quality of service over PoIs. Extensive simulations have been run using these PoIs in order to evaluate if and how the two different methods can effectively be used in reality. Several useful insights have been gained that will provide the basis for future work. The optimization approach in particular has proved to deliver good results within the limitations of the simulated environment used for testing

Handover Optimization in GSM

In telecommunications in general and in GSM in particular, the handover is a feature that guarantees a smooth transition of a call from one base station - that is for the purpose of this project an antenna - to another. In the recent ten years, the amount of data traffic through mobile telecommunications has doubled annually, putting an enormous strain on the network and forcing operators to upgrade with more and more base stations and new features. Although 3G and 4G are responsible for data traffic in most countries, GSM still provides more than 80% of the coverage for mobile devices around the world. Due to the increase in data traffic, 3G and 4G need to use more and more frequencies at the expense of GSM. An optimization of the GSM network is thus vital. In this project, we research two methods to automatically choose the parameters of interest (PoI) that govern the handover feature in each cell which is, roughly speaking, the area of coverage of one antenna. In one of these methods, the choice of cell- and cell-to-cell-specific parameters has its origins in control theory while the other method is based on mathematical optimization. In the mathematical sense, our goal is to optimize the quality of service over PoIs. Extensive simulations have been run using these PoIs in order to evaluate if and how the two different methods can effectively be used in reality. Several useful insights have been gained that will provide the basis for future work. The optimization approach in particular has proved to deliver good results within the limitations of the simulated environment used for testing

Spatial imaging of the furnace atomization plasma emission spectrometry source

The spatial distribution of background species and analyte in a He FAPES source have been determined using a charge-coupled device (CCD) imaging system. Imaging of the He 667.82 nm support gas line reveals the presence of two distinct plasmas: an intense luminous zone located around the centre electrode and a diffuse plasma near the tube walls. In a graphite tube at room temperature, the plasma system exhibits a significant dependence on the d.c. bias of the centre electrode for a constant forward r.f. power of 50 W. Polyatomic background species exhibit similar overall distributions and response to changes in the centre electrode d.c. bias. The ingress of atmospheric nitrogen into the plasma can be indirectly detected at elevated tube wall temperatures. Images obtained for Ag atomized into 30 W and 50 W plasmas point out the role of the centre electrode as a primary condensation and secondary re-volatilization site. Condensation and re-evaporation is alleviated when Ag is atomized into a 70 W plasma as the result of plasma-induced heating of the centre electrode.NRC publication: Ye

Two-dimensional imaging of excited analyte species in electrothermal vaporizers

Applications of a charge-coupled device (CCD) imaging spectrometer as a detection system for the determination of two-dimensional images of transient atomization events in a furnace atomization plasma emission spectrometric (FAPES) source are reviewed. Spectrally, spatially and temporally resolved images of the emission from analyte species (Ag(I), Ca(I) and Ca(II)) and plasma support gas (He(I)) in a 50 W He rf plasma are presented and the advantages of using a CCD camera system for fundamental characterization of vaporization, atomization, and ionization processes in the FAPES source are discussed. The limitations associated with the current system \u2014 insensitivity and limited spectral resolution \u2014 are highlighted and means of overcoming them are suggested.NRC publication: Ye

Condensation of analyte vapor species in graphite furnace atomic absorption spectrometry

NRC publication: Ye