Blue, green and yellow carbon dots derived from pyrogenic carbon: Structure and fluorescence behaviour

Fluorescence lifetimes and quantum yields featuring polycyclic aromatic hydrocarbons (PAHs) and other organics constituting pyrogenic carbon particulate matter (PM) are seldom measured. In this work, PM sampled in a fuel-rich ethylene flame was firstly separated in organic carbon (OC), soluble in dichloromethane, and refractory organic carbon (ROC), soluble in N-methyl pyrrolidinone, and then analyzed by size exclusion chromatography (SEC) coupled with online UV and fluorescence detection, and by offline fluorescence spectroscopy and mass spectrometry. It was found that three classes of differently light emitting carbon dots (CDs) could be bottom-up synthesized in the same flame system by selecting appropriately the residence time. Actually, OC presented blue fluorescence regardless the residence time, whereas ROC sampled at low and high residence time emitted fluorescence in the green (green CDs) and in the yellow (yellow CDs) region, respectively. The SEC molecular weight of all CDs presented similar trimodal distributions, centered around 300, 1000 and 10,000 u. For the first time fluorescence lifetimes and quantum yields of pyrogenic CD fractions were measured as additional parameters useful for discriminating the fluorescent components and inferring their structural properties, with the support of mass spectrometry. The different spectroscopic features of CDs could be associated to different compositional characteristics as the polydispersity of molecular components featuring blue CDs, opposed to the oligomer-like nature of green and yellow CDs. Pyrogenic CDs showed different fluorescence emission ranges, quantum yield and lifetimes, appealing for their possible applications in the fields of imaging, electronics and sensors

spectroscopic measurements for deuterium retention and lithium influx studies with lithium limiter on ftu

Spectroscopic measurements to determine deuterium and lithium fluxes were performed in recent experiments on FTU with a liquid lithium limiter (LLL) and an actively cooled limiter (CLL) using a multichannel spectrometer and using LiI–Dα filtered photodiodes. Using the S/XB method in combination with an absolute calibration, measurements of the LiI (670.8nm) and Dβ (464.8nm) spectral lines were used to estimate the deuterium and lithium fluxes from the limiters. The estimation of the lithium fluxes has shown increased values when the CLL is closer towards the last closed magnetic surface (LCMS), according to the measurements of infrared camera. This work shows that the spectroscopic diagnostics in the visible range can be an efficient tool to determine deuterium and liquid metal fluxes in FTU in order to better investigate the interaction between the plasma and the limiter materials. Keywords: Plasma spectroscopy, FTU, Limiter, LLL, CLL, Lithium flu

PAHs and fullerenes as structural and compositional motifs tracing and distinguishing organic carbon from soot

Examining the features distinguishing organic carbon from soot is crucial for understanding the source, the effect on the environment and their respective role in aerosol chemistry and soot formation. Beside to the obvious PAH picking-out in the low-mass mode (C number 40) of organic carbon, separated by carbon particulate matter extraction from young and mature soot thermophoretically sampled in premixed flames, was done by laser-desorption-time-of-flight mass spectrometry, exploiting the laser power increase. The perusal of organic carbon mass spectra through mathematical tools in comparison to aromatic and alkyl-substituted PAH-laden samples and the persistence of high-mass mode at high laser power led to exclude the contribution of dimers and alkyl-bridged PAHs attributing the second mode to both fully-benzenoid and cyclopenta-PAHs. Profound differences between mass spectra of organic carbon and soot were noticed as neither molecules nor radicals of PAHs could be drawn out from soot, even at high laser power, and only small radicals and carbon clusters like fullerenes were observed, especially for young soot. These inferences evidenced the importance of analysing separately organic carbon and soot especially if insights into soot particles nucleation are to be obtained. In the case of benzene flame, already at the inception, soot consists of strongly tangled aromatic motifs crosslinked each other, presumably deriving from reactive coagulation/clustering of relatively small aromatic hydrocarbons/radicals early formed. In methane and ethylene flames, coalesced liquid-like material composed of soot and PAHs is formed and transformed later on undergoing some carbonization and molecular growth, respectively

Optical Properties of Organic Carbon and Soot Produced in an Inverse Diffusion Flame

The carbonaceous matter (soot plus organic carbon) sampled downstream of an ethylene inverse diffusion flame (IDF) was chemically and spectroscopically analyzed in detail. In particular, the H/C ratio, the UV-Visible absorption coefficient and Raman parameters were measured and found to be representative of a highly disordered sp2 -rich carbon as the early soot sampled in a premixed flame. In contrast, the optical band gap was found to be relatively low (0.7eV), closer to the optical band gap of graphite than to that of medium-sized polycyclic aromatic hydrocarbons (\u3e2eV) which are widely considered to be soot precursors and are mostly contained in the organic carbon. The significance of the optical band gap as signature of different structural levels (nano-, micro- and macro-structure) of sp2 -rich aromatic disordered carbons was critically analyzed in reference to their molecular weight/size distribution. The relevance of the optical band analysis to the study of the soot formation mechanism was also highlighted

NMDA Receptor Phosphorylation at a Site Affected in Schizophrenia Controls Synaptic and Behavioral Plasticity

Phosphorylation of the NR1 subunit of NMDA receptors (NMDARs) at serine (S) 897 is markedly reduced in schizophrenia patients. However, the role of NR1 S897 phosphorylation in normal synaptic function and adaptive behaviors are unknown. To address these questions, we generated mice in which the NR1 S897 is replaced with alanine (A). This knock-in mutation causes severe impairment in NMDAR synaptic incorporation and NMDAR-mediated synaptic transmission. Furthermore, the phosphomutant animals have reduced AMPA receptor (AMPAR)-mediated synaptic transmission, decreased AMPAR GluR1 subunit in the synapse, and impaired long-term potentiation. Finally, the mutant mice exhibit behavioral deficits in social interaction and sensorimotor gating. Our results suggest that an impairment in NR1 phosphorylation leads to glutamatergic hypofunction that can contribute to behavioral deficits associated with psychiatric disorders

Characterization of Chimeric Lipopolysaccharides from Escherichia coli Strain JM109 Transformed with Lipooligosaccharide Synthesis Genes (lsg) from Haemophilus influenzae

Previously, we reported the expression of chimeric lipopolysaccharides (LPS) in Escherichia coli strain JM109 (a K-12 strain) transformed with plasmids containing Haemophilus influenzae lipooligosaccharide synthesis genes (lsg) (Abu Kwaik, Y., McLaughlin, R. E., Apicella, M. A., and Spinola, S. M. (1991) Mol. Microbiol. 5, 2475–2480). In this current study, we have analyzed the O-deacylated LPS and free oligosaccharides from three transformants (designated pGEMLOS-4, pGEMLOS- 5, and pGEMLOS-7) by matrix-assisted laser desorption ionization, electrospray ionization, and tandem mass spectrometry techniques, along with composition and linkage analyses. These data show that the chimeric LPS consist of the complete E. coli LPS core structure glycosylated on the 7-position of the non-reducing terminal branch heptose with oligosaccharides from H. influenzae. In pGEMLOS-7, the disaccharide Gal13 3GlcNAc13 is added, and in pGEMLOS-5, the structure is extended to Gal134GlcNAc133Gal133GlcNAc13. PGEMLOS-5 LPS reacts positively with monoclonal antibody 3F11, an antibody that recognizes the terminal disaccharide of lacto-N-neotetraose. In pGEMLOS-4 LPS, the 3F11 epitope is apparently blocked by glycosylation on the 6-position of the terminal Gal with either Gal or GlcNAc. The biosynthesis of these chimeric LPS was found to be dependent on a functional wecA (formerly rfe) gene in E. coli. By using this carbohydrate expression system, we have been able to examine the functions of the lsg genes independent of the effects of other endogenous Haemophilus genes and expressed proteins

Environmental protection through nuclear energy

Environmental protection through implementation of green energies is progressively becoming a daily reality. Numerous sources of green energy were introduced in recent years. Although this process initially started with difficulties, it finally resulted in an acceleration and implementation of new green energy technologies. Nonetheless, new major obstacles are emerging. The most worldwide difficult obstacle encountered, especially for wind and photovoltaic electric power plants, is the not regular and predictable green energy production. This study proposes solutions designed to solve this unpleasant aspect of irregular production of green energy. The basic idea refers to the construction of specially designed nuclear power plants acting as energy buffers. Nuclear power plants, indeed, may behave as proper energy buffers able to work to a minimum capacity when the green energy (i.e., wind power or PV) is steadily produced (namely, when the energy generated by the turbines or PV panels is at full constant capacity) but that can also run at progressively increased capacities when the wind or solar energy production reduces or stops. The work get two major contributions: 1-propose to the achievement of an energy buffer using nuclear power plants (for the moment on nuclear fission); 2-shows some theoretical aspects important needed to carry out the reaction of the fusion

Transcriptional profiling identifies the metabolic phenotype of gonococcal biofilms

Neisseria gonorrhoeae, the etiologic agent of gonorrhea, is frequently asymptomatic in women, often leading to chronic infections. One factor contributing to this may be biofilm formation. N. gonorrhoeae can form biofilms on glass and plastic surfaces. There is also evidence that biofilm formation may occur during natural cervical infection. To further study the mechanism of gonococcal biofilm formation, we compared transcriptional profiles of N. gonorrhoeae biofilms to planktonic profiles. Biofilm RNA was extracted from N. gonorrhoeae 1291 grown for 48 h in continuous-flow chambers over glass. Planktonic RNA was extracted from the biofilm runoff. In comparing biofilm with planktonic growth, 3.8% of the genome was differentially regulated. Genes that were highly upregulated in biofilms included aniA, norB, and ccp. These genes encode enzymes that are central to anaerobic respiratory metabolism and stress tolerance. Downregulated genes included members of the nuo gene cluster, which encodes the proton-translocating NADH dehydrogenase. Furthermore, it was observed that aniA, ccp, and norB insertional mutants were attenuated for biofilm formation on glass and transformed human cervical epithelial cells. These data suggest that biofilm formation by the gonococcus may represent a response that is linked to the control of nitric oxide steady-state levels during infection of cervical epithelial cells

Something about the Balancing of Thermal Motors

Internal combustion engines in line (regardless of whether the work in four-stroke engines and two-stroke engines Otto cycle engines, diesel and Lenoir) are, in general, the most used. Their problem of balancing is extremely important for their operation is correct. There are two possible types of balancing: Static and dynamic balance. The total static to make sure that the sum of the forces of inertia of a mechanism to be zero. There are also a static balance partial. Dynamic balance means to cancel all the moments (load) inertia of the mechanism. A way of the design of an engine in a straight line is that the difference between the crank 180 [°] or 120 [°]. A different type of construction of the engine is the engine with the cylinders in the opposite line, called "cylinder sportsmen". In this type of engine (regardless of their position, which is most often vertical) for engines with two cylinders, one has a static balance total and an imbalance in the dynamic. Similar to the model of the earth concentrated in rotation movement are resolved and load balancing shafts rotating parts. An important way to reduce losses of heat engines is how to achieve a better balance. The methods may be used in equal measure and on engines with external combustion, type Stirling or Watt

Metabolic state alters economic decision making under risk in humans

Background: Animals' attitudes to risk are profoundly influenced by metabolic state (hunger and baseline energy stores). Specifically, animals often express a preference for risky (more variable) food sources when below a metabolic reference point (hungry), and safe (less variable) food sources when sated. Circulating hormones report the status of energy reserves and acute nutrient intake to widespread targets in the central nervous system that regulate feeding behaviour, including brain regions strongly implicated in risk and reward based decision-making in humans. Despite this, physiological influences per se have not been considered previously to influence economic decisions in humans. We hypothesised that baseline metabolic reserves and alterations in metabolic state would systematically modulate decision-making and financial risk-taking in humans. Methodology/Principal Findings: We used a controlled feeding manipulation and assayed decision-making preferences across different metabolic states following a meal. To elicit risk-preference, we presented a sequence of 200 paired lotteries, subjects' task being to select their preferred option from each pair. We also measured prandial suppression of circulating acyl-ghrelin (a centrally-acting orexigenic hormone signalling acute nutrient intake), and circulating leptin levels (providing an assay of energy reserves). We show both immediate and delayed effects on risky decision-making following a meal, and that these changes correlate with an individual's baseline leptin and changes in acyl-ghrelin levels respectively. Conclusions/Significance: We show that human risk preferences are exquisitely sensitive to current metabolic state, in a direction consistent with ecological models of feeding behaviour but not predicted by normative economic theory. These substantive effects of state changes on economic decisions perhaps reflect shared evolutionarily conserved neurobiological mechanisms. We suggest that this sensitivity in human risk-preference to current metabolic state has significant implications for both real-world economic transactions and for aberrant decision-making in eating disorders and obesity