Studying Systematic Errors on Estimation Decision, Detection, and Quantification Limit on Micro-TLC

The decision limit (CCα), capability of detection (CCβ) and quantification limit (QL) are importance performance characteristics in method validation. The TLC-Scanner 3 from Camag provides the possibility to choose the slit dimension of light to determine the peak chromatogram of a substance. The influence of the slit dimension for determination of CCα, CCβ and QL of paracetamol has been carried out. Paracetamol was spotted onto plates of AL-TLC Si G 60 F254 by linomat 4 in the range of 50–400 ng/spot and 10–400 ng/band, then on twin chambers eluted with TAEA (toluene:acetone-ethanol:conc.ammonia, 45 + 45 + 7 + 3 v/v) for 45 mm. Eluted spots were scanned in different slit dimensions at 248 nm. The CCα, CCβ and QL of paracetamol were estimated through the linear regression (LRM) and signal-to-noise (S/N) methods. Slit lengths between 50 and 133 % of the band width of the spots, and with the noise factor of the slit under 2.6, produced good precision measurements of TLC-densitometry between plates, while slit lengths between 50 and 83 % of the band width of the spots introduced a higher sensitivity response of the detector. The estimated CCα, CCβ and QL were determined by how the data were collected, the analytical optical setting, and the usage method for the estimation of both validation parameters.     

Archetypal shapes based on landmarks and extension to handle missing data

Archetype and archetypoid analysis are extended to shapes. The objective is to find representative shapes. Archetypal shapes are pure (extreme) shapes. We focus on the case where the shape of an object is represented by a configuration matrix of landmarks. As shape space is not a vectorial space, we work in the tangent space, the linearized space about the mean shape. Then, each observation is approximated by a convex combination of actual observations (archetypoids) or archetypes, which are a convex combination of observations in the data set. These tools can contribute to the understanding of shapes, as in the usual multivariate case, since they lie somewhere between clustering and matrix factorization methods. A new simplex visualization tool is also proposed to provide a picture of the archetypal analysis results. We also propose new algorithms for performing archetypal analysis with missing data and its extension to incomplete shapes. A well-known data set is used to illustrate the methodologies developed. The proposed methodology is applied to an apparel design problem in children.     

Synthesis of C3 benzo[1,2-e:3,4-e':5,6-e"]tribenzo[l]acephenanthrylenes ("crushed fullerene" derivatives) by intramolecular palladium-catalyzed arylation

The C60 polyarenes 4, 5, 18 a, and 18 b have been synthesized from truxene by triple alkylation at C5, C10, and C15 followed by a palladium-catalyzed intramolecular arylation. The synthesis of "crushed fullerene" C60H30 (2) is the most efficient reported to date and proceeds in 33% overall yield.     

A semiempirical conformational analysis of the 3-phenyl-1,2,3-oxathiazolidine 2-oxide

An extensive conformational search for the heterocyclic compound 3-phenyl-1,2,3-oxathiazolidine 2-oxide has been carried out using the semiempirical quantum-mechanical method PM3. All torsion angles were varied in the geometry optimization procedure which led to the prediction of four distinct conformers. Barriers to internal rotation leading to conformational interconversions were also calculated. The results of the present study indicate that this five-member ring substituted heterocyclic system may be expected to exist as a mixture of stable conformers rather than a unique molecular entity.     

Probing the differential effects of infrared light sources IR1072 and IR880 on human lymphocytes: evidence of selective cytoprotection by IR1072

Light therapy, both laser and LED, have been shown to provide clinical benefit in many therapeutic arenas. The effects of IR1072 and IR880 were investigated, using a range of single and multiple irradiation protocols, for their effect on freshly prepared human lymphocytes stimulated with phytohemagglutinin. Viable cell numbers remained significantly higher after irradiation with IR1072 and were significantly lower after IR880 irradiation compared to untreated controls, following a daily single irradiation over a 5-day period. Cell numbers were significantly higher after pre-treatment with IR1072 and exposure to UVA, compared to cells treated with UVA only. Cells irradiated twice on Day 3 post-harvest with various wavebands confirm on Day 5, an increase in % cell viability after IR1072, and IR1072 alternating with IR1268 irradiation, and a decrease in % cell viability after IR880 irradiation alone. Further, wavebands tested displayed no significant differences compared to the control. Cells were collected after exposure on Days 3 and 5 with IR1072 and IR880 treatments and protein levels were compared using quantitative immunoblotting probed with an anti-iNOS antibody. Following IR1072, but not IR880, treatment there was a 4.9+/-2.1-fold higher iNOS protein expression in treated cells compared to the control on Day 5 post-treatment.     

A case study in forensic chemistry: The Bali bombings

The Bali bombings on 12 October 2002 killed 202 people and caused international outrage. The police investigation referred to as “Operation Alliance” involved the Indonesian National Police, the Australian Federal Police and others, resulted in the arrests of key personnel and exposed the link between Jemaah Islamiah (JI) and al-Queda.This paper describes aspects of the investigation from a forensic chemists perspective. The recovery of water soluble residues from blast scenes and suspect's residences is a challenging task that requires a meticulous and methodical approach. The concept of deploying forensic chemists and setting up a “mobile laboratory” from the outset proved to be a highly effective and efficient way to process large numbers of samples and assist investigators with relevant information at the time that it was most needed. It also identified the need for a new generation of field portable instruments.     

Modified Taylor approximation of functions with periodic behaviour

We approximate a function with periodic behaviour by means of a small modification of its Taylor polynomial. This modification is based on the work of Scheifele and will simplify the construction of special numerical methods for differential equations with near periodic solutions.     

The $$$$-means algorithm for 3D shapes with an application to apparel design

Clustering of objects according to shapes is of key importance in many scientific fields. In this paper we focus on the case where the shape of an object is represented by a configuration matrix of landmarks. It is well known that this shape space has a finite-dimensional Riemannian manifold structure (non-Euclidean) which makes it difficult to work with. Papers about clustering on this space are scarce in the literature. The basic foundation of the \(k\)-means algorithm is the fact that the sample mean is the value that minimizes the Euclidean distance from each point to the centroid of the cluster to which it belongs, so, our idea is integrating the Procrustes type distances and Procrustes mean into the \(k\)-means algorithm to adapt it to the shape analysis context. As far as we know, there have been just two attempts in that way. In this paper we propose to adapt the classical \(k\)-means Lloyd algorithm to the context of Shape Analysis, focusing on the three dimensional case. We present a study comparing its performance with the Hartigan-Wong \(k\)-means algorithm, one that was previously adapted to the field of Statistical Shape Analysis. We demonstrate the better performance of the Lloyd version and, finally, we propose to add a trimmed procedure. We apply both to a 3D database obtained from an anthropometric survey of the Spanish female population conducted in this country in 2006. The algorithms presented in this paper are available in the Anthropometry R package, whose most current version is always available from the Comprehensive R Archive Network.