Microdevices in mass spectrometry

Miniaturization of laboratory instrumentation is becoming critical in achieving the speed and throughput required by the current revolutionary progress in biology. This mini review critically summarizes the present status of microfluidic devices designed for use in mass spectrometry.     

Semiempirical and DFT computations of the influence of Tb(III) dopant on unit cell dimensions of cerium(III) fluoride

Several computational methods, both semiempirical and ab initio, were used to study the influence of the amount of dopant on crystal cell dimensions of CeF₃ doped with Tb³⁺ ions (CeF₃:Tb³⁺). AM1, RM1, PM3, PM6, and PM7 semiempirical parameterization models were used, while the Sparkle model was used to represent the lanthanide cations in all cases. Ab initio calculations were performed by means of GGA+U/PBE projector augmented wave density functional theory. The computational results agree well with the experimental data. According to both computation and experiment, the crystal cell parameters undergo a linear decrease with increasing amount of the dopant. The computations performed using Sparkle/PM3 and DFT methods resulted in the best agreement with the experiment with the average deviation of about 1% in both cases. Typical Sparkle/PM3 computation on a 2×2×2 supercell of CeF3:Tb3+ lasted about two orders of magnitude shorter than the DFT computation concerning a unit cell of this material. © 2014 Wiley Periodicals, Inc.     

Fragment‐based similarity searching with infinite color space

Fragment‐based searching and abstract representation of molecular features through reduced graphs have separately been used for virtual screening. Here, we combine these two approaches and apply the algorithm RedFrag to virtual screens retrospectively and prospectively. It uses a new type of reduced graph that does not suffer from information loss during its construction and bypasses the necessity of feature definitions. Built upon chemical epitopes resulting from molecule fragmentation, the reduced graph embodies physico‐chemical and 2D‐structural properties of a molecule. Reduced graphs are compared with a continuous‐similarity‐distance‐driven maximal common subgraph algorithm, which calculates similarity at the fragmental and topological levels. The performance of the algorithm is evaluated by retrieval experiments utilizing precompiled validation sets. By predicting and experimentally testing ligands for endothiapepsin, a challenging model protease, the method is assessed in a prospective setting. Here, we identified five novel ligands with affinities as low as 2.08 μM. © 2015 Wiley Periodicals, Inc.     

1H and 13C NMR Analysis of Poly(succinimide) Prepared by Microwave-Enhanced Polycondensation of L-Aspartic Acid

Poly(succinimide) (PSI) is a polymer of aspartic acid with interesting properties and numerous possible uses. Application areas include agriculture, cleaning agents, metallurgy, the building industry, wastewater treatment, medicine, pharmaceuticals, bioengineering, and many more. Therefore, the particular structure analysis is crucial for these purposes, especially considering possible reactions between monomer and solvent used in the polycondensation process. Moreover, utilization of microwave irradiation in such synthesis is conducive to reducing reaction time and improving yield. In this article, the detailed structure analysis of PSI prepared under microwave irradiation conditions as well as a comparison study with thermally synthesized PSI are presented.     

Natural radioactivity in groundwater – a review

The issue of natural radioactivity in groundwater is reviewed, with emphasis on those radioisotopes which contribute in a significant way to the overall effective dose received by members of the public due to the intake of drinking water originating from groundwater systems. The term ‘natural radioactivity’ is used in this context to cover all radioactivity present in the environment, including man-made (anthropogenic) radioactivity. Comprehensive discussion of radiological aspects of the presence of natural radionuclides in groundwater, including an overview of current regulations dealing with radioactivity in drinking water, is provided. The presented data indicate that thorough assessments of the committed doses resulting from the presence of natural radioactivity in groundwater are needed, particularly when such water is envisaged for regular intake by infants. They should be based on a precise determination of radioactivity concentration levels of the whole suite of radionuclides, including characterisation of their temporal variability. Equally important is a realistic assessment of water intake values for specific age groups. Only such an evaluation may provide the basis for possible remedial actions.