Evaluation of Digital Image Recognition Methods for Mass Spectrometry Imaging Data Analysis

Analyzing mass spectrometry imaging data can be laborious and time consuming, and as the size and complexity of datasets grow, so does the need for robust automated processing methods. We here present a method for comprehensive, semi-targeted discovery of molecular distributions of interest from mass spectrometry imaging data, using widely available image similarity scoring algorithms to rank images by spatial correlation. A fast and powerful batch search method using a MATLAB implementation of structural similarity (SSIM) index scoring with a pre-selected reference distribution is demonstrated for two sample imaging datasets, a plant metabolite study using Artemisia annua leaf, and a drug distribution study using maraviroc-dosed macaque tissue.

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2D temperature measurements in the wake of a heated cylinder using LIF

A technique is described to measure the instantaneous 2D temperature distribution in the wake of a heated cylinder using `laser-induced fluorescence'. Rhodamine B, a fluorescent dye, is used as a temperature indicator. The relation between fluorescence intensity and temperature is determined by means of calibration experiments in the temperature range of 20–35 °C with an accuracy of ±0.1 °C. The temperature distribution behind the heated cylinder is well visible and can be measured with a high spatial resolution. Corrections for variation in laser energy and intensity distribution in the laser sheet have to be made to further improve the accuracy of the measuring method. Received: 3 January 2001/Accepted: 18 May 2001     

Hadronization of quark systems

Hadronization in simple models of quark systems is discussed with emphasis on the combinatorial aspects. The numberN of quarks and the numberN _c of colours are the relevant variables. In onedimension and in the meson and baryon sector the problem is completely soluble. When multiquark hadrons are included an iterative procedure still allows a complete solution. Higher dimensions are difficult to treat but global hadronization, without dimensionality constraints, is again soluble. As a general result the baryon/meson ratio is, for large quark densities, rather large, ?1/3 and may grow without limit asN→∞.     

Synthesis of novel 3-deoxy-3-C-triazolylmethyl-allose derivatives and evaluation of their biological activity

Recently, monosaccharide-triazole conjugates have proved to possess a large variety of useful biological activities. This paper describes synthesis of a new series of 3-deoxy-3-C-triazolylmethyl-allose derivatives. These new compounds are obtained from acetonide-protected 3-deoxy-3-azidomethyl allose and commercial alkynes via Cu(I) catalyzed 1,3-dipolar cycloaddition. The obtained molecular scaffolds differ from those described earlier by the presence of a methylene linker (-CH₂-) between the C(3) of allose and the triazole moiety. It was demonstrated that acetonide-protected monosaccharide, 3-deoxy-3-C-(4-phenyl-1H-1,2,3-triazol-1-yl)methyl-1,2:5,6-di-O-isopropylidene-α-d-allofuranose, inhibited α-L-fucosidase for 26% at 0.1 mM concentration, but a deprotected analog, 3-deoxy-3-C-(4-(4-tert-butylphenyl)-1H-1,2,3-triazol-1-yl)methyl-β-d-allofuranose, showed 15% inhibition of β-glucosidase at 1 mM concentration.      

Spin-disorder resistivity in the Cu2Mn(Al1−xSnx) heusler alloys

Electrical resistivity measurements have been performed on the Cu₂Mn(Al_1?xSn_x) Heusler alloys, where x = 0; 0.05; 0.10; 0.15, in the temperature range of 4–800 K. The experimental curves clearly show the importance of the ferromagnetic character on the resistivities of the alloys. The results obtained are in agreement with an interpretation in terms of a spin-disorder model.     

Expeditious asymmetric synthesis of a stereoheptad corresponding to the C(19)-C(27)-ansa chain of rifamycins: formal total synthesis of Rifamycin S

In the presence of sulfur dioxide and an acid promoter, (-)-(1E,3Z)-2-methyl-1-((1S)-1-phenylethoxy)penta-1,3-dien-3-yl isobutyrate reacts with (Z)-3-(trimethylsilyloxy)pent-2-ene giving a silyl sulfinate intermediate that undergoes, in the presence of palladium catalyst, a desilylation and retro-ene elimination of SO(2) with formation of (-)-(1Z,2S,3R,4S)-1-ethylidene-2,4-dimethyl-5-oxo-3-((1S)-1-phenylethoxy)-heptyl isobutyrate as major product. This ethyl ketone undergoes cross-aldol reaction with (2S)-2-methyl-3-[(tert-butyldimethylsilyl)oxy]propanal giving an aldol that is reduced into a stereoheptad corresponding to the C(19)-C(27)-segment of Rifamycins with high diastereoselectivity and enantiomeric excess.     

Transamidation reactions of 2-(2-sulfonylguanidino)acetamides

The reactivity of a series of sulfonylguanidinoacetamides 2A-E towards amines is reported. Guanidinoacetamides 2A-C, containing the arylsulfonylimino moiety, undergo a facile transamidation to give substituted carboxamides 4A-C, through the imidazolidinone intermediate 3. Acetamide 2D, having a methanesulfonylimino substituent, affords the imidazolidinone 3D and no transamidated carboxamides 4 are detected. In the case of guanidinoacetamide 2E, with a p-nitrobenzenesulfonylimino substituent, a Smiles rearrangement was observed.     

Synthesis of long-chain polyketide fragments by reaction of 1,3-dioxy-1,3-dienes with allylsilanes: umpolung with sulfur dioxide

[reaction: see text] In the presence of a Lewis or protic acid and at low temperature, 1,3-dioxy-1,3-dienes add to sulfur dioxide generating zwitterionic intermediates that can react with carbon nucleophiles such as allylsilanes. After a retro-ene elimination of SO(2), valuable polyketide precursors are obtained.