Evaluating the metabolic perturbations in Mangifera indica (mango) ripened with various ripening agents/practices through gas chromatography ‐ mass spectrometry based metabolomics

Mangifera indica L. (mango) is said to be the king of fruits due to its rich nutritional properties and mainly originates from the Indian sub‐continent. The consumption pattern of the mangoes has increased drastically, due to which, many ripening practices/agents were used to make it ready‐to‐eat fruit or juice for the consumers. The fruit quality and metabolic composition are said to be altered due to different ripening agents/practices. The present communication mainly deals to understand the metabolic perturbations in mango fruits due to different ripening practices/agents (room temperature ripening, ethylene, and calcium carbide) using gas chromatography ‐ mass spectrometry based metabolomics. The partial least square‐discriminant analysis has found 16 differential metabolites for different ripening agents/practices which are belong to the classes of amino acids, fatty acids, sugars, and polyols. Four metabolic pathways were found to alter in the fruit metabolome due to different ripening agents/practices. Fructose, glucose, and galactose were found to be significantly up‐regulated due to calcium carbide ripening in comparison to other ripening agents/practices. Overall findings from the present study advocates that mass spectrometry based metabolomics can be valuable tool to understand the fruit quality and safety with respect to consumer health.     

Data shaving: a focused screening approach

The number of compounds available for evaluation as part of the drug discovery process continues to increase. These compounds may exist physically or be stored electronically allowing screening by either actual or virtual means. This growing number of compounds has generated an increasing need for effective strategies to direct screening efforts. Initial efforts toward this goal led to the development of methods to select diverse sets of compounds for screening, methods to cluster actives into related groups of compounds, and tools to select compounds similar to actives of interest for further screening. In this work we extend these earlier efforts to exploit information about inactive compounds to help make rational decisions about which sets of compounds to include as part of a continuing screening campaign, or as part of a focused follow-up effort. This method uses the information from inactive compounds to "shave" off or deprioritize compounds similar to inactives from further consideration. This methodology can be used in two ways: first, to provide a rational means of deciding when sufficient compounds containing certain structural features have been tested and second as a tool to enhance similarity searching around known actives. Similarity searching is improved by deprioritizing compounds predicted to be inactive, due to the presence of structural features associated with inactivity.     

Characterization of diamond surface terminations using electrochemical grafting with diazonium salts

A new characterization technique to identify qualitatively diamond surface terminations and to measure quantitatively the density of hydrogen atoms bonded to the diamond surface is introduced using electrochemical grafting of diamond with diazonium salts. The cathodic peak potentials for the grafting of nitrophenyl layers reveal qualitative information about surface terminations ranging from –H, to –OH to –O–. The charges consumed during the conversion of nitro- to aminophenyl are used to calculate quantitatively the density of hydrogen atoms bonded to the diamond surface. As hydrogen is generally very difficult to detect by other methods like X-ray Photon Spectroscopy, this new method will add significantly to the understanding of surface related properties of transducers.     

Resisting resistance: new chemical strategies for battling superbugs

As microbes become increasingly resistant to antibiotics, and in many cases to several drugs simultaneously, the search is on to find new therapies. One method to combat resistance is to use inhibitors of resistance mechanisms to potentiate existing antibiotics. Recent efforts are encouraging and highlight the importance of research at the chemistry-microbiology interface in developing new approaches to tackle resistance.     

Investigation of isothiocyanate addition to alkylidene derivatives of malononitrile and cyanoacetic acid esters

Addition of arylisothiocyanates to active methylene compounds leads to a variety of compounds depending on the structure of the starting material and conditions used to conduct the addition. Addition of arylisothiocyanate to 1c leads to a pyrido[2,3-d]pyrimidine resulting from addition of a second mole of cyanate to the initial adduct. Addition of arylisothiocyanate to 1b led to a mixture of pyridine and thiopyran adducts, while addition to 1a led to open chain structures.     

Static fatigue fracture of polyethylene: A morphological analysis

The fracture properties of a number of high-density polyethylenes were evaluated and related to their morphology. The resistance to initiation of fracture is related to the resistance to voiding of the materials and the rate of coalescence of voids. The propensity of the materials to void has been shown to be related to the size of the amorphous region. The resistance to propagation of the fracture is also related to the above factors as well as the ease of stretching and rupture of fibrils. The ease of fibril formation has been shown to be related to the degree of perfection of the crystallites.     

Internal quality controls applied in inductively coupled plasma mass spectrometry multi-elemental analysis in the second French Total Diet Study

In 2006, the French Food Safety Agency (AFSSA) started the second French Total Diet Study to assess exposure to essential and non-essential elements through dietary intake by analysing 1352 food samples. A total of 21 elements were analysed to date by Inductively Coupled Plasma Mass Spectrometry after closed vessel microwave digestion, in 660 samples corresponding to at half of the study. This work presents and discusses the results of the various internal quality controls (IQC) applied to ensure that the analytical procedure is correctly carried out, from digestion to analysis, and to enable analytical chemists to validate the results obtained. The whole IQC allows to estimate uncertainties according to elements and to select those that should be discarded from the study or only given as indicative values for elements that were not within defined quality limits.     

Gradient Elution Centrifugal Partition Chromatography: Comparison with HPLC Gradients and use of Ternary Diagrams to Build Gradients

Abstract

Just as with HPLC, gradient elution provides to CPC an easy way to fractionate solutes of widely differing polarities and partition coefficients, and to reduce run times. The easiest way to design a gradient for CPC is to refer to ternary diagrams corresponding to the ternary liquid mixtures generally encountered in centrifugal partition chromatography.     

Synthetic, self-assembly ABCD nanoparticles; a structural paradigm for viable synthetic non-viral vectors

Gene therapy research is still in trouble owing to a paucity of acceptable vector systems to deliver nucleic acids to patients for therapy. Viral vectors are efficient but may be too dangerous. Synthetic non-viral vectors are inherently safer but are currently not efficient enough to be clinically viable. The solution for gene therapy lies with improved synthetic non-viral vectors systems. This review is focused on synthetic cationic liposome/micelle-based non-viral vector systems and is a critical review written to illustrate the increasing importance of chemistry in gene therapy research. This review should be of primary interest to synthetic chemists and biomedical researchers keen to appreciate emerging technologies, but also to biological scientists who remain to be convinced about the relevance of chemistry to biology.     

NMR spectroscopic study of the Murex trunculus dyeing process

It is widely accepted that indigo dyes derived from Murex trunculus were used to produce the biblical dyes tekhelet and argaman. We describe a method of following the debromination of natural leucoindigos and their binding to wool using NMR spectroscopy. Debromination is observed prior to reaction with the wool and prior to oxidation. Binding to the wool is shown to occur prior to oxidation. NMR allows the dyeing process to be followed. This, in principle, could be used to correct problems during dyeing that would increase the reliability of the process.     

Precision of Flash Pyrolysis-GC-MS Analysis: Experimental Evaluation of the Sources of Variability

The present study was carried out to evaluate the precision and to identify significant sources of variability in flash pyrolysis-GC-MS experiments. The analysis of variance has been applied to the example of polyethylene pyrolysis to estimate the impact of several controlled factors: sample handling, flash pyrolysis filament ageing and calibration. It was demonstrated that to get the best precision in experimental results, it is recommended to set the operator to reduce the impact of sample handling procedure and the filament to avoid variability due to changes in filament characteristics. In comparison, filament ageing and filament calibration are shown to influence in a limited extent the experimental results.     

Exploring supramolecular interactions and architectures by scanning force microscopies

The development of new methodologies based on scanning force microscopy (SFM) has made it possible to map topographies, chemical functionalities, and numerous other physicochemical properties of complex assemblies, to unravel dynamic processes, to measure forces generated along a reaction coordinate, to nanopattern surfaces and to nanomanipulate objects. This tutorial review highlights the most recent applications of these SFM-based capabilities, on and beyond imaging, to the exploration of supramolecular interactions and architectures, to the fabrication of smart materials and to the optimization of (nano)devices.     

Fragmentations de quelques Derives thiophosphores sous L'impact electronique. II—Migration de groupes phenyles et d'atomes de soufre dans quelques derives dithiophosphores

Some compounds having two diphenylphosphino or diphenylthiophosphoranyl groups give rise by electron-impact-induced fragmentation to varied migrations of phenyl groups or of sulfur atoms. According to the compound, the phenyl moves by migration from one phosphorous to the other, or to the sulfur which is bound to the other phosphorous. Migration of the phenyl from the phosphorous towards the carbon arises when this is strongly electrophilic. The thiophosphorous compounds also give rise to sulfur atom migrations from the phosphorous to the carbon, or to the double bond placed in α of phosphorous atom.     

Use of drug discovery tools in rational organometallic catalyst design

A computational procedure is detailed where techniques common in the drug discovery process-2D- and 3D-quantitative structure-activity relationships (QSAR)-are applied to rationalize the catalytic activity of a synthetically flexible, Ti-N=P ethylene polymerization catalyst system. Once models relating molecular properties to catalyst activity are built with the two QSAR approaches, two database mining approaches are used to select a small number of ligands from a larger database that are likely to produce catalysts with high activity when grafted onto the Ti-N=P framework. The software employed throughout this work is freely available, is easy to use, and was applied in a "black box" approach to highlight areas where the drug discovery tools, designed to address organic molecules, have difficulty in addressing issues arising from the presence of a metal atom. In general, 3D-QSAR offers an efficient way to screen new potential ligands and separate those likely to lead to poor catalysts from those that are likely to contribute to highly active catalysts. The results for 2D-QSAR appear to be quantitatively unreliable, likely due to the presence of a metal atom; nonetheless, there is evidence that qualitative predictions from different models may be reliable. Pitfalls in the database mining techniques are identified, none of which are insurmountable. The lessons learned about the potential uses and drawbacks of the techniques described herein are readily applicable to other catalyst frameworks, thereby enabling a rational approach to catalyst improvement and design.     

Measurement of <Emphasis Type="Italic">T</Emphasis><Subscript>g</Subscript> in lyophilized protein and protein excipient mixtures by dynamic mechanical analysis

The glass transition of lyophilized materials is normally measured by conventional or temperature modulated differential scanning calorimetry (TMDSC). However, because of the weakness of these transitions when protein concentrations are high, these techniques are often unable to detect the glass transition (T _g). High ramp rate DSC, where heating rates of 100 K per min and higher are used, has been shown to be able to detect weak transitions in a wide range of materials and has been applied to these materials in previous work. Dynamic mechanical analysis (DMA) is also known to be much more sensitive to the presence of relaxations in materials than other commonly used thermal techniques. The development of a method to handle powders in the DMA makes it now possible to apply this technique to protein and protein-excipient mixtures. HRR DSC, TMA and DMA were used to characterize the glass transition of lyophilized materials and the results correlated. DMA is shown to be a viable alternative to HRR DSC and TMA for lyophilized materials.     

A second-order perturbation theory route to vibrational averages and transition properties of molecules: general formulation and application to infrared and vibrational circular dichroism spectroscopies

A general formulation to compute anharmonic vibrational averages and transition properties at the second-order of perturbation theory is derived from the Rayleigh-Schro?dinger development. This approach is intended to be applicable to any property expanded as a Taylor series up to the third order with respect to normal coordinates or their associated momenta. The equations are straightforward to implement and can be easily adapted to various properties, as illustrated for the case of electric and magnetic dipole moments. From those, infrared and vibrational circular dichroism spectra can be readily obtained. This fully automatic procedure has been applied to several chiral molecules of small-to-medium sizes and compared to the standard double harmonic approximation and to experimental data.     

半夏淀粉的理化特性

研究了不同产地的4种半夏淀粉的理化特性,包括直链淀粉含量、膨胀度、溶解性、持水性、淀粉粒大小和形貌、结晶类型、热特性和糊化特性等。结果表明,这些半夏淀粉中直链淀粉含量为18.60%～23.91%;膨胀度21.53%～23.09%;溶解度11.5%～32.3%;持水性100.3%～119.0%。淀粉粒单粒球形,卵形或圆半球形,直径2～20μm,复粒由2～3个分粒组成,其结晶类型均为C型,结晶度15.0%～37.9%。用差示扫描量热仪测得的转变温度TO、TP和TC分别为71.58～77.75℃、83.03～83.84℃和89.41～90.99℃,热焓为4.316～5.809 J/g。用快速粘度分析仪测定了4种半夏淀粉的糊化特征值:峰值粘度、热糊粘度、冷糊粘度、稀懈值和回复值分别为149.5～226.2、97.7～127.2、141.8～194.3、50.4～99.0和44.2～67.2 RVU。糊化温度77.8～79.9℃,峰值时间8.3～8.7 min。     

Synthesis and Rearrangement Reactions of C-Alkylidene Carbohydrates

Direct: olefinations on one hand in comparison to eliminations of aldols cf various uloses on the other each proved to be specific as to the sice of unsaturation in the branched-chain products, found to be interconvertible with one exception under a variety of conditions. Although shown to be generally equivalent to its Witcig-counterpart:, the Peterson reagent employed is liable to cause eliminations in the initial olefin. One of the branched-chain products appears to be of unusual molecular rigidity as evidenced by a large 5J coupling.     

Advanced Reprocessing Developments in Europe Status on European Projects ACSEPT and ACTINET-I3

Nuclear energy has more than ever to demonstrate that it can contribute safely and on a sustainable way to answer the international increase in energy needs. Actually, in addition to an increased safety of the reactors themselves, its acceptance is still closely associated to our capability to reduce the lifetime of the nuclear waste, to manage them safely and to propose options for a better use of the natural resources. Spent fuel reprocessing can help to reach these objectives. At the European level, ACSEPT and ACTINET-I3 have worked together to improve our knowledge in actinide chemistry and advanced separation process development.