Chemical components of organic aerosol (OA) selectively absorb light at short wavelengths. In this study, the prevalence, sources, and optical importance of this so-called brown carbon (BrC) aerosol ...component are investigated throughout the North American continental tropospheric column during a summer of extensive biomass burning. Spectrophotometric absorption measurements on extracts of bulk aerosol samples collected from an aircraft over the central USA were analyzed to directly quantify BrC abundance. BrC was found to be prevalent throughout the 1 to 12 km altitude measurement range, with dramatic enhancements in biomass-burning plumes. BrC to black carbon (BC) ratios, under background tropospheric conditions, increased with altitude, consistent with a corresponding increase in the absorption Aangstrom exponent (AAE) determined from a three-wavelength particle soot absorption photometer (PSAP). The sum of inferred BC absorption and measured BrC absorption at 365 nm was within 3 % of the measured PSAP absorption for background conditions and 22 % for biomass burning. A radiative transfer model showed that BrC absorption reduced top-of-atmosphere (TOA) aerosol forcing by ~ 20 % in the background troposphere. Extensive radiative model simulations applying this study background tropospheric conditions provided a look-up chart for determining radiative forcing efficiencies of BrC as a function of a surface-measured BrC : BC ratio and single scattering albedo (SSA). The chart is a first attempt to provide a tool for better assessment of brown carbon's forcing effect when one is limited to only surface data. These results indicate that BrC is an important contributor to direct aerosol radiative forcing.
•HITRAN2016 molecular spectroscopic database is described.•Dynamic web interface at www.hitran.org is introduced.•HITRAN Application Programming Interface is introduced.•Substantial extent of the ...amount and quality of the data highlighted.•Many new spectroscopic parameters are now available in HITRAN.
This paper describes the contents of the 2016 edition of the HITRAN molecular spectroscopic compilation. The new edition replaces the previous HITRAN edition of 2012 and its updates during the intervening years. The HITRAN molecular absorption compilation is composed of five major components: the traditional line-by-line spectroscopic parameters required for high-resolution radiative-transfer codes, infrared absorption cross-sections for molecules not yet amenable to representation in a line-by-line form, collision-induced absorption data, aerosol indices of refraction, and general tables such as partition sums that apply globally to the data. The new HITRAN is greatly extended in terms of accuracy, spectral coverage, additional absorption phenomena, added line-shape formalisms, and validity. Moreover, molecules, isotopologues, and perturbing gases have been added that address the issues of atmospheres beyond the Earth. Of considerable note, experimental IR cross-sections for almost 300 additional molecules important in different areas of atmospheric science have been added to the database. The compilation can be accessed through www.hitran.org. Most of the HITRAN data have now been cast into an underlying relational database structure that offers many advantages over the long-standing sequential text-based structure. The new structure empowers the user in many ways. It enables the incorporation of an extended set of fundamental parameters per transition, sophisticated line-shape formalisms, easy user-defined output formats, and very convenient searching, filtering, and plotting of data. A powerful application programming interface making use of structured query language (SQL) features for higher-level applications of HITRAN is also provided.
Background
Chronic subdural haematoma (CSDH) is a pathology that is frequently encountered by neurosurgeons. Nevertheless, there is a lack of guidelines based on solid evidence. There has been a ...recent and considerable increase in the interest on management and outcomes for CSDH. Therefore, we systematically reviewed all currently running randomised controlled trials (RCTs) in chronic subdural haematoma to understand the areas under investigation and plan future collaborative trials.
Methods
Clinical trials databases (Cochrane Controlled Register of Trials, WHO ICTRP and clinical
trials.gov
) were searched for trials relevant to chronic subdural haematoma. It was then established which trials were currently running and fulfilled robust research methodology for a RCT.
Results
There are 26 currently running RCTs in CSDH, with the most common topics covering application of steroids (7), surgical techniques (5) and tranexamic acid (5). Further to this, there are trials running on other pharmacological agents (4), middle meningeal artery (MMA) embolisation (2) and peri-operative management (3).
Conclusions
Pharmacological agents are a particular focus of CSDH management currently, and a wealth of studies on steroids will hopefully lead to more harmonised, evidence-based practice regarding this in the near future. Surgical techniques and new procedures such as MMA embolisation are also important focuses for improving patient outcomes. There is an on-going need for future RCTs and evidence-based guidelines in CSDH, particularly including low- and middle-income countries, and it is hoped that the establishment of the iCORIC (International COllaborative Research Initiative on Chronic Subdural Haematoma) will help address this.
The secret behind excitation-dependent/-independent photoluminescence of carbon nanodots (CDs) is not yet revealed completely. To address this issue, a detailed investigation on solvent ...polarity-dependent optical properties of citric acid–urea co-derived nitrogen-doped carbon nanodots (NCDs) was carried out. The interpretation on UV–visible spectral data reveals the presence of H-aggregates formed through hydrogen bonding. In addition, dipole–dipole interaction-mediated J-aggregates are clearly evident. The broad and intense excitation band of NCDs is mostly contributed by highly emissive J-like self-assembly of H-aggregates in polar solvents. Time-resolved fluorescence spectra of NCDs show triexponential decay kinetics. The three lifetime components correspond to long-lived H-aggregates, short-lived J-aggregates, and JH-aggregates of intermediate lifetime. Moreover, fluorescence of NCD is influenced by concentration and storage time. Accordingly, mismatch in spectral shapes of excitation and absorption spectra of NCD can be successfully correlated to aggregate species of NCDs that exist even in very dilute solutions.
Detection of TNT by fluorescent and colorimetric method by using polyethylene imine capped fluorescent copper nanocluster.
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•Polyethylene imine capped fluorescent copper nanoclusters ...were prepared via a one pot microwave assisted method.•The cost-effective nanosensor served as fluorescent and colorimetric TNT sensor with excellent sensitivity and selectivity.•In fluorescent and colorimetric detection LOD obtained is as low as 14 pM and 0.05nM respectively.•A portable paper sensor was developed which can selectively detect TNT vapors.
Rapid, reliable, onsite approaches for the trace level detection of trinitrotoluene (TNT) is a pressing necessity for both homeland security and environmental protection. Selective detection of TNT from other nitroaromatics is still challenging as it possess similar chemical structure and properties with its analogues. In the present work, the water soluble polyethylene imine protected copper nanoclusters (PEI CuNC) were developed as fluorescent and colorimetric probe which can detect TNT selectively and sensitively both in aqueous and vapour form. The PEI CuNC with size less than 3nm was prepared via a simple one pot microwave method and exhibited bright blue emission at 480nm. The fluorescence of PEI CuNC can be remarkably quenched by TNT through the formation of amine-TNT Meisenheimer complex. Quenching was further facilitated by fluorescence resonance energy transfer (FRET) and inner filter effect (IFE). A good linearity was observed for the PEI CuNC based fluorescence detection of TNT with limit of detection 14 pM. Meanwhile the formation of Meisenheimer complex resulted in a significant colour change of the solution from pale green to red, which enables visual detection of TNT with detection limit down to 0.05nM. The fluorescence as well as colorimetric method displayed excellent selectivity and sensitivity over other interfering compounds and ions. Fluorescent paper strip sensor was developed to detect TNT in vapour phase as well as solution form. PEI CuNC coated paper strips were able to detect TNT vapours with in one minute with a limit of detection 10nM, providing a valuable platform for sensing TNT in public safety and security.
Paper-based sensors are a new alternative technology for fabricating simple, low-cost, portable and disposable analytical devices for many application areas including clinical diagnosis, food quality ...control and environmental monitoring. The unique properties of paper which allow passive liquid transport and compatibility with chemicals/biochemicals are the main advantages of using paper as a sensing platform. Depending on the main goal to be achieved in paper-based sensors, the fabrication methods and the analysis techniques can be tuned to fulfill the needs of the end-user. Current paper-based sensors are focused on microfluidic delivery of solution to the detection site whereas more advanced designs involve complex 3-D geometries based on the same microfluidic principles. Although paper-based sensors are very promising, they still suffer from certain limitations such as accuracy and sensitivity. However, it is anticipated that in the future, with advances in fabrication and analytical techniques, that there will be more new and innovative developments in paper-based sensors. These sensors could better meet the current objectives of a viable low-cost and portable device in addition to offering high sensitivity and selectivity, and multiple analyte discrimination. This paper is a review of recent advances in paper-based sensors and covers the following topics: existing fabrication techniques, analytical methods and application areas. Finally, the present challenges and future outlooks are discussed.
Hyperbilirubinemia is the condition when bilirubin exceeds normal concentration in body (19.80 mg/mL in newborns and 1.19 × 10−2 mg/mL in adults). Bilirubin encephalopathy in newborns may cause ...irreversible neurological disorders. Current methods for detection of bilirubin suffer from compromising accuracy. In the present work, bovine serum albumin stabilized copper nanocluster (BSA-CuNCs) was synthesized via a one pot microwave assisted method as a turn on detector for bilirubin. The synthesized BSA-CuNCs having size less than 4 nm, exhibited bright blue emission at 405 nm. Interestingly, no observable change in fluorescence emission was noticed over a wide pH range (1–11) or at high ionic conditions. However, the interaction of Fe3+ with BSA-CuNCs induces quenching of fluorescence. Moreover, the fluorescence can be regained by the addition of bilirubin over other possible coexisting biomolecules. A good linearity was observed for BSA-CuNCs based turn on probe with a Limit of Detection (LoD) 6.62 nM. Furthermore, real sample analyses were carried out with human serum and urine which showed good recovery percentage.
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•BSA-CuNCs were synthesized via microwave assisted method.•BSA-CuNCs can be quenched by Fe3+.•BSA-CuNCs/ Fe3+ act as a turn on platform for bilirubin.•The designed probe shows LOD of 6.62 nM.
•Dual fuelled hydrogen powered diesel engine studied with nano additives.•CNT is least stable than TiO2 and Al2O3.•TiO2 and CNT shows profound reduction in BSFC and improved BTE.•Reduction in the ...formation of unburned hydrocarbons.•NOx reduced from 450 to 350 ppm of biodiesel blended with CNT nanoadditive.
In this study, the impact of nanoparticles and hydrogen blends on combustion, performance and emission characteristics of modified dual fuel engine was investigated. The nanoparticles TiO2, CNT, Al2O3, CuO and CeO2 are dispersed at a fraction of 100 ppm with 20% hydrogen to form blends HT100, HCT100, HA100, HCE100 and HC100 respectively. The nanoparticles are agitated using ultrasonication process to increase the stability of blends. All blends are tested at 1800 rpm for different engine load varying from 0%, 25%, 50%, 75% and 100% respectively. The addition of nanoparticles does not show a substantial effect on density, kinematic viscosity and flash point and cetane number. Further, the nanoparticles CNT and TiO2 showed a better stability with 30% and 21% absorption rate at 240 h sedimentation time. All tested nanoparticles showed a profound change in the maximum cylinder pressure rates in comparison to neat diesel. Besides, the addition of CeO2 and Al2O3 improves the brake thermal efficiency by 4.3% and 2.5%. Meanwhile no significant change in brake specific fuel consumption is recorded for CeO2. The nanoparticles CNT and TiO2 reports 23% and 22% reduced BSFC than other blends. The results of exhaust emission showed addition of hydrogen and nanoparticles decreases the emission of carbon monoxide, carbon dioxide and hydrocarbon significantly. However, regarding NOx emission only CNT showed a profound decrease in NOx than other blends. From the results it is evident that, addition of nanoparticles and hydrogen on neat diesel improves the combustion characteristics and engine performance with reduced exhaust gas emission.
The HITRAN2012 molecular spectroscopic database Rothman, L.S.; Gordon, I.E.; Babikov, Y. ...
Journal of quantitative spectroscopy & radiative transfer,
November 2013, 2013-11-00, 20131101, 2013-11, Letnik:
130
Journal Article
Recenzirano
Odprti dostop
This paper describes the status of the 2012 edition of the HITRAN molecular spectroscopic compilation. The new edition replaces the previous HITRAN edition of 2008 and its updates during the ...intervening years. The HITRAN molecular absorption compilation is comprised of six major components structured into folders that are freely accessible on the internet. These folders consist of the traditional line-by-line spectroscopic parameters required for high-resolution radiative-transfer codes, infrared absorption cross-sections for molecules not yet amenable to representation in a line-by-line form, ultraviolet spectroscopic parameters, aerosol indices of refraction, collision-induced absorption data, and general tables such as partition sums that apply globally to the data. The new HITRAN is greatly extended in terms of accuracy, spectral coverage, additional absorption phenomena, and validity. Molecules and isotopologues have been added that address the issues of atmospheres beyond the Earth. Also discussed is a new initiative that casts HITRAN into a relational database format that offers many advantages over the long-standing sequential text-based structure that has existed since the initial release of HITRAN in the early 1970s.
•A new edition of the HITRAN molecular spectroscopic database is described.•HITRAN now includes a large number of molecules and their isotopologues.•HITRAN is now applicable to planetary atmospheres in addition to terrestrial.•A new structure for the database is described.•Many new spectroscopic phenomena are now available for the user.
Colorectal cancer is a leading cause of cancer-related deaths. Mutations in the innate immune sensor AIM2 are frequently identified in patients with colorectal cancer, but how AIM2 modulates colonic ...tumorigenesis is unknown. Here, we found that Aim2-deficient mice were hypersusceptible to colonic tumor development. Production of inflammasome-associated cytokines and other inflammatory mediators was largely intact in Aim2-deficient mice; however, intestinal stem cells were prone to uncontrolled proliferation. Aberrant Wnt signaling expanded a population of tumor-initiating stem cells in the absence of AIM2. Susceptibility of Aim2-deficient mice to colorectal tumorigenesis was enhanced by a dysbiotic gut microbiota, which was reduced by reciprocal exchange of gut microbiota with healthy wild-type mice. These findings uncover a synergy between a specific host genetic factor and gut microbiota in determining the susceptibility to colorectal cancer. Therapeutic modulation of AIM2 expression and microbiota has the potential to prevent colorectal cancer.
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•AIM2 is required to mediate protection against colorectal cancer•AIM2 suppresses overt proliferation in enterocytes•AIM2 inhibits expansion of the intestinal stem cell population•Transfer of healthy microbiota dampens tumor development in Aim2-deficient mice
The cytosolic DNA sensor AIM2 regulates stem cell proliferation in the intestinal mucosa in an inflammasome-independent fashion, contributing to a decrease in the likelihood of colorectal cancer development.
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