Substituent effects on absorption spectra of pH indicators: an experimental and computational study of sulfonphthaleine dyes

Sulfonphthaleine dyes are an important class of pH indicators, finding applications in novel (textile) sensors. In this paper, we present a combined experimental and theoretical study to elucidate the halochromic behaviour of a large set of sulfonphthaleine compounds. Starting from an experimental analysis consisting of UV-Vis spectroscopy, the pH region and the absorption wavelengths related to the colour shift are obtained and pK(a) values are derived. The effect of the substituents on the pH region can be traced back to their electron donating/withdrawing properties. Time-Dependent Density Functional Theory (TD-DFT) is able to adequately produce the trend in experimental wavelengths. Proton affinities are used to assess the effect of substituents on the pH region. The combination of theory and experiment is able to give a better understanding of the pH sensitivity; the methodology in this work will be useful in future dye design and is applicable to other dye classes as well. (C) 2013 Elsevier Ltd. All rights reserved

Polycaprolactone and polycaprolactone/chitosan nanofibres functionalised with the pH-sensitive dye Nitrazine Yellow

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The pH-sensitive properties of azo dyes in aqueous environment

Azo dyes consist of a double nitrogen-nitrogen bond connected to two aromatic moieties, creating a large conjugated pi-system. A relatively simple synthesis and large variety of colours have made azo dyes the most abundant class of colourants. The dye studied in this research, ethyl orange (EO), is a prototypical example of a halochromic (pH-sensitive) azo dye. Halochromic dyes have already proven useful for application in textile sensors since the colour change of such sensors is easy to perceive and the advantages of the parent materials (e.g. flexibility) are maintained.[1] The key to further development of smart materials is combining multiple responses that can be separately addressed by different triggers.[2] To achieve this, we need a full knowledge of the colour changing mechanism and the influence of the environment. Herein, both theoretical and experimental methods were used to unravel the halochromic properties of EO.[3] Experimental UV-VIS and Raman spectra point towards a structural change of EO in water between pH 5 and pH 3. This pH-sensitivity is modeled through a series of ab initio computations on the neutral, various singly and doubly protonated structures. Static calculations (with inclusion of implicit solvation) are successful in assigning the most probable protonation site. However, to fully understand the origin of the main absorption peaks, a molecular dynamics simulation study in a water molecular environment is used in combination with Time Dependent-DFT calculations to deduce average UV-VIS spectra which take into account the flexibility of the dye and the explicit interactions with the surrounding water molecules. The proposed methodology allows to achieve a remarkable agreement between the theoretical and experimental UV-VIS spectrum and enables to fully unravel the pH sensitive behaviour of EO in aqueous environment. References: [1] L. Van der Schueren and K. De Clerck, Textile Research Journal 80(7) 590-603 (2010). [2] M. A. C. Stuart et al., Nature Materials, 9(2) 101-113 (2010). [3] T. De Meyer et al., submitted to Chemistry - A European Journa

Тантризм в контексте теории мистического опыта просветления

У статті досліджується індійський тантризм і робиться висновок, що він постає іманентним містичним напрямом, який стверджує тотожність індивідуального та абсолютного духовного начал. Він відноситься до холічного містицизму, що закликає до прийняття матеріального буття у всіх його аспектах. Основними методами просвітлення у тантризмі є медитація і різноманітні види йоги тіла (пранаяма, асана, сексуальна йога). Не використовується в цій формі містичного досвіду такий метод як бхакті, почуттєво-емоційне служіння Абсолюту шляхом віри та любові.В статье исследуется индийский тантризм и делается вывод, что он является имманентным мистическим направлением, которое утверждает тождественность индивидуального и абсолютного духовного начал. Он относится к холическому мистицизму, который призывает к приятию всех аспектов материального бытия. В качестве основных методов просветления в тантризме используется медитация и разнообразные виды йоги тела (пранаяма, асана, сексуальная йога). Практически не используется в данной форме мистического опыта такой метод как бхакти, чувственно-эмоциональное служение Абсолюту путем любви и веры.The article studies Indian tantrism and the conclusion can be made that it is an immanent mystical policy which affirms the identity of individual and absolute origins. It has to do with the whole mysticism which appeals to accept all the aspects of the material being. As the main methods of enlightening tantrism uses meditation and different kinds of body yoga (pranayama, asana, sexual yoga). Such method as bhakti, the sensual and emotional service to the Absolute by means of love and faith, is not practically used in this form of the mystical experience

Paternal age at birth is an important determinant of offspring telomere length

Although evidence supports the function of telomere length (TL) as a marker for biological aging, no major determinants of TL are known besides inheritance, age and gender. Here we validate and, more importantly, assess the impact of paternal age at birth as a determinant for the offspring's peripheral blood leukocyte TL within the Asklepios study population. Telomere restriction fragment length and paternal age information were available for 2433 volunteers (1176 men and 1257 women) aged similar to 35-55 years old. Paternal age at birth was positively associated with offspring TL (offspring age and gender adjusted, P < 10 (-14)). The increase in TL was estimated at 17 base pairs for each supplemental year at birth and was not statistically different between male and female offspring. The effect size of paternal age outweighed the classical TL determinant gender by a factor of 2, demonstrating the large impact. Maternal age at birth was not independently associated with offspring TL. The peculiar interaction between paternal age at birth and inheritance might explain a large part of the genetic component of TL variance on a population level. This finding also provides further proof for the theory that TL is not completely reset in the zygote. Furthermore, as paternal age is subject to demographic evolution, its association with TL might have a substantial impact on the results and comparability of TL within and between epidemiological studies. In conclusion, paternal age is an important determinant for TL, with substantial consequences for future studies

Reversal of aging-induced increases in aortic stiffness by targeting cytoskeletal protein-protein interfaces

Background: The proximal aorta normally functions as a critical shock absorber that protects small downstream vessels from damage by pressure and flow pulsatility generated by the heart during systole. This shock absorber function is impaired with age because of aortic stiffening. Methods and Results: We examined the contribution of common genetic variation to aortic stiffness in humans by interrogating results from the AortaGen Consortium genome-wide association study of carotid-femoral pulse wave velocity. Common genetic variation in the N-WASP (WASL) locus is associated with carotid-femoral pulse wave velocity (rs600420, P=0.0051). Thus, we tested the hypothesis that decoy proteins designed to disrupt the interaction of cytoskeletal proteins such as N-WASP with its binding partners in the vascular smooth muscle cytoskeleton could decrease ex vivo stiffness of aortas from a mouse model of aging. A synthetic decoy peptide construct of N-WASP significantly reduced activated stiffness in ex vivo aortas of aged mice. Two other cytoskeletal constructs targeted to VASP and talin-vinculin interfaces similarly decreased aging-induced ex vivo active stiffness by on-target specific actions. Furthermore, packaging these decoy peptides into microbubbles enables the peptides to be ultrasound-targeted to the wall of the proximal aorta to attenuate ex vivo active stiffness. Conclusions: We conclude that decoy peptides targeted to vascular smooth muscle cytoskeletal protein-protein interfaces and microbubble packaged can decrease aortic stiffness ex vivo. Our results provide proof of concept at the ex vivo level that decoy peptides targeted to cytoskeletal protein-protein interfaces may lead to substantive dynamic modulation of aortic stiffness

Leukocyte telomere length and diet in the apparently healthy, middle-aged Asklepios population

Telomere length is a prognostic biomarker for aging diseases. As it is unknown whether diet plays a role in these associations, we aimed to assess the impact of diet on telomere length. Moreover, given that telomere length is modulated by oxidative stress and inflammation, an additional goal was to evaluate whether the latter may mediate possible telomere - diet associations. Southern blot measured leukocyte telomere length and food frequency questionnaire data were compared for 2509 apparently healthy men and women (similar to 35 to 55 years) from the Asklepios population. No significant associations were found between telomere length and overall dietary characteristics, such as dietary diversity, quality, equilibrium, and the dietary inflammatory index. Exploratory analysis of individual dietary variables revealed that a higher daily intake of deep fried potato products was associated with shorter telomeres (P = 0.002, 151 bp per 100 g/day), also in both sexes separately. Deep fried potato product consumption was also significantly associated with C-reactive protein (P = 0.032) and uric acid (P = 0.042), but not other inflammation and oxidative stress markers. These results suggest an at most limited association between overall dietary patterns and telomere length in the general population. Nevertheless, the association between telomere length and deep fried potato product intake warrants additional research

Detuning effects in the one-photon mazer

The quantum theory of the mazer in the non-resonant case (a detuning between the cavity mode and the atomic transition frequencies is present) is written. The generalization from the resonant case is far from being direct. Interesting effects of the mazer physics are pointed out. In particular, it is shown that the cavity may slow down or speed up the atoms according to the sign of the detuning and that the induced emission process may be completely blocked by use of a positive detuning. It is also shown that the detuning adds a potential step effect not present at resonance and that the use of positive detunings defines a well-controlled cooling mechanism. In the special case of a mesa cavity mode function, generalized expressions for the reflection and transmission coefficients have been obtained. The general properties of the induced emission probability are finally discussed in the hot, intermediate and cold atom regimes. Comparison with the resonant case is given.Comment: 9 pages, 8 figure

Using next-generation sequencing to improve DNA barcoding: lessons from a small-scale study of wild bee species (Hymenoptera, Halictidae)

International audienceAbstractThe parallel sequencing of targeted amplicons is a scalable application of next-generation sequencing (NGS) that can advantageously replace Sanger sequencing in certain DNA barcoding studies. It can be used to sequence different PCR products simultaneously, including co-amplified products. Here, we explore this approach by simultaneously sequencing five markers (including the DNA barcode and a diagnostic marker of Wolbachia) in 12 species of Halictidae that were previously DNA barcoded using Sanger sequencing. Consensus sequences were obtained from fresh bees with success rates of 74–100% depending on the DNA fragment. They improved the phylogeny of the group, detected Wolbachia infections (in 8/21 specimens) and characterised haplotype variants. Sequencing cost per marker and per specimen (11.43 €) was estimated to decrease (< 5.00 €) in studies aiming for a higher throughput. We provide guidelines for selecting NGS or Sanger sequencing depending on the goals of future studies