Synthesis and Oligonucleotide Incorporation of Fluorescent Cytosine Analogue tC: a Promising Nucleic Acid Probe

The tricyclic cytosine, tC, is a fluorescent base analogue with excellent properties for investigating intrinsic characteristics of nucleic acid as well as interactions between nucleic acids and other molecules. Its unique fluorescence properties and insignificant influence on overall structure and dynamics of nucleic acid after incorporation makes tC particularly interesting in fluorescence resonance energy transfer and anisotropy measurements. We here describe a straightforward synthesis of the standard monomer form of tC for DNA solid-phase synthesis, the tC phosphoramidite, and its subsequent incorporation into oligonucleotides. The total synthesis of the tC phosphoramidite takes approximately 8 days and its incorporation and the subsequent oligonucleotide purification an additional day

On the Inability of Markov Models to Capture Criticality in Human Mobility

We examine the non-Markovian nature of human mobility by exposing the inability of Markov models to capture criticality in human mobility. In particular, the assumed Markovian nature of mobility was used to establish a theoretical upper bound on the predictability of human mobility (expressed as a minimum error probability limit), based on temporally correlated entropy. Since its inception, this bound has been widely used and empirically validated using Markov chains. We show that recurrent-neural architectures can achieve significantly higher predictability, surpassing this widely used upper bound. In order to explain this anomaly, we shed light on several underlying assumptions in previous research works that has resulted in this bias. By evaluating the mobility predictability on real-world datasets, we show that human mobility exhibits scale-invariant long-range correlations, bearing similarity to a power-law decay. This is in contrast to the initial assumption that human mobility follows an exponential decay. This assumption of exponential decay coupled with Lempel-Ziv compression in computing Fano's inequality has led to an inaccurate estimation of the predictability upper bound. We show that this approach inflates the entropy, consequently lowering the upper bound on human mobility predictability. We finally highlight that this approach tends to overlook long-range correlations in human mobility. This explains why recurrent-neural architectures that are designed to handle long-range structural correlations surpass the previously computed upper bound on mobility predictability

Higher media multi-tasking activity is associated with smaller gray-matter density in the anterior cingulate cortex

Media multitasking, or the concurrent consumption of multiple media forms, is increasingly prevalent in today’s society and has been associated with negative psychosocial and cognitive impacts. Individuals who engage in heavier media-multitasking are found to perform worse on cognitive control tasks and exhibit more socio-emotional difficulties. However, the neural processes associated with media multi-tasking remain unexplored. The present study investigated relationships between media multitasking activity and brain structure. Research has demonstrated that brain structure can be altered upon prolonged exposure to novel environments and experience. Thus, we expected differential engagements in media multitasking to correlate with brain structure variability. This was confirmed via Voxel-Based Morphometry (VBM) analyses: Individuals with higher Media Multitasking Index (MMI) scores had smaller gray matter density in the anterior cingulate cortex (ACC). Functional connectivity between this ACC region and the precuneus was negatively associated with MMI. Our findings suggest a possible structural correlate for the observed decreased cognitive control performance and socio-emotional regulation in heavy media-multitaskers. While the cross-sectional nature of our study does not allow us to specify the direction of causality, our results brought to light novel associations between individual media multitasking behaviors and ACC structure differences

Chronic psychosocial and financial burden accelerates 5-year telomere shortening: findings from the Coronary Artery Risk Development in Young Adults Study.

Leukocyte telomere length, a marker of immune system function, is sensitive to exposures such as psychosocial stressors and health-maintaining behaviors. Past research has determined that stress experienced in adulthood is associated with shorter telomere length, but is limited to mostly cross-sectional reports. We test whether repeated reports of chronic psychosocial and financial burden is associated with telomere length change over a 5-year period (years 15 and 20) from 969 participants in the Coronary Artery Risk Development in Young Adults (CARDIA) Study, a longitudinal, population-based cohort, ages 18-30 at time of recruitment in 1985. We further examine whether multisystem resiliency, comprised of social connections, health-maintaining behaviors, and psychological resources, mitigates the effects of repeated burden on telomere attrition over 5 years. Our results indicate that adults with high chronic burden do not show decreased telomere length over the 5-year period. However, these effects do vary by level of resiliency, as regression results revealed a significant interaction between chronic burden and multisystem resiliency. For individuals with high repeated chronic burden and low multisystem resiliency (1 SD below the mean), there was a significant 5-year shortening in telomere length, whereas no significant relationships between chronic burden and attrition were evident for those at moderate and higher levels of resiliency. These effects apply similarly across the three components of resiliency. Results imply that interventions should focus on establishing strong social connections, psychological resources, and health-maintaining behaviors when attempting to ameliorate stress-related decline in telomere length among at-risk individuals

A new Rhodococcus aetherivorans strain isolated from lubricant-contaminated soil as a prospective phenol biodegrading agent

Microbe-based decontamination of phenol-polluted environments has significant advantages over physical and chemical approaches by being relatively cheaper and ensuring complete phenol degradation. There is a need to search for commercially prospective bacterial strains that are resistant to phenol and other co-pollutants, e.g. oil hydrocarbons, in contaminated environments, and able to carry out efficient phenol biodegradation at a variable range of concentrations. This research characterizes the phenol-biodegrading ability of a new actinobacteria strain isolated from a lubricant-contaminated soil environment. Phenotypic and phylogenetic analyses showed that the novel strain UCM Ac-603 belonged to the species Rhodococcus aetherivorans, and phenol degrading ability was quantitatively characterized for the first time. R. aetherivorans UCM Ac-603 tolerated and assimilated phenol (100% of supplied concentration) and various hydrocarbons (56.2–94.4%) as sole carbon sources. Additional nutrient supplementation was not required for degradation and this organism could grow at a phenol concentration of 500 mg L −1 without inhibition. Complete phenol assimilation occurred after 4 days at an initial concentration of 1750 mg L −1 for freely-suspended cells and at 2000 mg L −1 for vermiculite-immobilized cells: 99.9% assimilation of phenol was possible from a total concentration of 3000 mg L −1 supplied at daily fractional phenol additions of 750 mg L −1 over 4 days. In terms of phenol degradation rates, R. aetherivorans UCM Ac-602 showed efficient phenol degradation over a wide range of initial concentrations with the rates (e.g. 35.7 mg L −1 h −1 at 500 mg L −1 phenol, and 18.2 mg L −1 h −1 at 1750 mg L −1 phenol) significantly exceeding (1.2–5 times) reported data for almost all other phenol-assimilating bacteria. Such efficient phenol degradation ability compared to currently known strains and other beneficial characteristics of R. aetherivorans UCM Ac-602 suggest it is a promising candidate for bioremediation of phenol-contaminated environments. </p

Application of Graphene within Optoelectronic Devices and Transistors

Scientists are always yearning for new and exciting ways to unlock graphene's true potential. However, recent reports suggest this two-dimensional material may harbor some unique properties, making it a viable candidate for use in optoelectronic and semiconducting devices. Whereas on one hand, graphene is highly transparent due to its atomic thickness, the material does exhibit a strong interaction with photons. This has clear advantages over existing materials used in photonic devices such as Indium-based compounds. Moreover, the material can be used to 'trap' light and alter the incident wavelength, forming the basis of the plasmonic devices. We also highlight upon graphene's nonlinear optical response to an applied electric field, and the phenomenon of saturable absorption. Within the context of logical devices, graphene has no discernible band-gap. Therefore, generating one will be of utmost importance. Amongst many others, some existing methods to open this band-gap include chemical doping, deformation of the honeycomb structure, or the use of carbon nanotubes (CNTs). We shall also discuss various designs of transistors, including those which incorporate CNTs, and others which exploit the idea of quantum tunneling. A key advantage of the CNT transistor is that ballistic transport occurs throughout the CNT channel, with short channel effects being minimized. We shall also discuss recent developments of the graphene tunneling transistor, with emphasis being placed upon its operational mechanism. Finally, we provide perspective for incorporating graphene within high frequency devices, which do not require a pre-defined band-gap.Comment: Due to be published in "Current Topics in Applied Spectroscopy and the Science of Nanomaterials" - Springer (Fall 2014). (17 pages, 19 figures

Interface properties and built-in potential profile of a LaCr O3/SrTi O3 superlattice determined by standing-wave excited photoemission spectroscopy

LaCrO3(LCO)/SrTiO3(STO) heterojunctions are intriguing due to a polar discontinuity along [001], exhibiting two distinct and controllable charged interface structures [(LaO)+/(TiO2)0 and (SrO)0/(CrO2)-] with induced polarization, and a resulting depth-dependent potential. In this study, we have used soft- and hard-x-ray standing-wave excited photoemission spectroscopy (SW-XPS) to quantitatively determine the elemental depth profile, interface properties, and depth distribution of the polarization-induced built-in potentials. We observe an alternating charged interface configuration: a positively charged (LaO)+/(TiO2)0 intermediate layer at the LCOtop/STObottom interface and a negatively charged (SrO)0/(CrO2)- intermediate layer at the STOtop/LCObottom interface. Using core-level SW data, we have determined the depth distribution of species, including through the interfaces, and these results are in excellent agreement with scanning transmission electron microscopy and electron energy-loss spectroscopy mapping of local structure and composition. SW-XPS also enabled deconvolution of the LCO and STO contributions to the valence-band (VB) spectra. Using a two-step analytical approach involving first SW-induced core-level binding-energy shifts and then VB modeling, the variation in potential across the complete superlattice is determined in detail. This potential is in excellent agreement with density functional theory models, confirming this method as a generally useful tool for interface studies

GYY4137, a slow-releasing hydrogen sulfide donor, ameliorates renal damage associated with chronic obstructive uropathy.

PURPOSE: Chronic obstructive uropathy can cause irreversible kidney injury, atrophy, and inflammation, which can ultimately lead to fibrosis. Epithelial-mesenchymal transition (EMT) is a key trigger of fibrosis and is caused by upregulation of transforming growth factor beta 1 (TGF-β1) and angiotensin II (ANGII). Hydrogen sulfide (H2S) is an endogenously produced gasotransmitter with cytoprotective properties. The present study aims to elucidate the effects of the slow-releasing H2S donor GYY4137 on chronic ureteral obstruction and evaluate potential mechanisms. MATERIALS AND METHODS: Following unilateral ureteral obstruction (UUO), male Lewis rats were given daily intraperitoneal (IP) administration of phosphate buffered saline (PBS) vehicle (UUO group) or PBS+200μmol/kg GYY4137 (UUO+GYY4137 group) for 30 days. Urine and serum samples were collected to determine physiological parameters of renal function and injury. Kidneys were removed on post-operative day 30 for evaluation of histopathology and protein expression. EMT in pig kidney epithelial cells (LLC-PK1) was induced with TGF-β1 and treated with GYY4137 to evaluate potential mechanisms via in vitro scratch wound assays. RESULTS: H2S treatment decreased serum creatinine and urine protein/creatinine excretion ratio following UUO. In addition, H2S mitigated cortical loss, inflammatory damage, and tubulointerstitial fibrosis. Tissues exhibited decreased expression of EMT markers upon H2S treatment. EMT progression in LLC-PK1 was alleviated upon in vitro administration of GYY4137. CONCLUSIONS: Our findings demonstrate, for the first time, the protective effects of H2S in chronic obstructive uropathy and may represent a potential therapeutic solution to ameliorate renal damage and improve clinical outcomes of urinary obstruction.This work was supported by a grant from the Lawson Health Research Foundation

Diets containing sea cucumber (Isostichopus badionotus) meals are hypocholesterolemic in young rats

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