5,549 research outputs found
Infrared studies of ortho-para conversion at Cl-atom and H-atom impurity centers in cryogenic solid hydrogen
No full textAbstract not availableP. L. Raston, S. C. Kettwich, and D. T. Anderso
The Cl + H(2) -> HCl + H Reaction Induced by IR + UV Irradiation of Cl(2) in Solid para-H(2): experiment
No full textWe report IR + UV coirradiation photolysis experiments conducted on Cl2-doped para-hydrogen (p-H2) crystals at 1.8 K, using pulsed 355 nm UV radiation and cw broad-band near-IR light from a FTIR tungsten source. The amount of HCl photoproduct is monitored using FTIR spectroscopy as a function of the IR + UV exposure time. Detailed analysis of the HCl growth kinetics reveals that the reaction Cl + H2(v=1,J=0) → HCl + H is playing a significant (15%) role in the in situ photochemistry. In contrast, UV-only photolysis experiments conducted under similar conditions produce almost exclusively (99%) isolated Cl atom photofragments, indicating the reaction Cl + H2(v=0,J=0) → HCl + H is not readily occurring. This combination of photolysis experiments confirms that under these conditions, the Cl + H2 reaction probability increases by a factor greater than 25 for Cl atom reactions with H2(v=1) versus H2(v=0). These results are therefore consistent with the expectation that vibrational excitation of the H2 reagent lowers the reaction threshold and increases the reaction cross section for the Cl + H2 reaction. These experimental studies were motivated by and are compared to the quantum model simulations reported by Korolkov, Manz, and Schild in the accompanying paper.Sharon C. Kettwich, Paul L. Raston, and David T. Anderso
Room-Temperature Vortex Fluidic Flow Chemistry Synthesis of Full Color Carbon Dots
No full textCarbon dots (CDs) as a new class of photoluminescent zero-dimension carbon nanoparticles have attracted significant research interests owing to their extraordinary opto-electro-properties and biocompatibility. So far, almost all syntheses of CDs require either heat treatment or exertion of high energy fields. Herein, a scalable room-temperature vortex fluidic method is introduced to the CDs synthesis using the angled vortex fluidic device (VFD). By judicious selection of the solvent, typical CDs precursor of phenylenediamine has been converted into high crystalline CDs through VFD processing. The VFD-synthesized CDs cover the full color spectrum from blue to red with the highest quantum yield of 45.6 %. The synthesis shows that the dynamic thin liquid film generated by VFD spun at high rotational speed (7–9 k RPM) is able to induce cycloaddition reactions. The new method for CD synthesis is facile, occurring under ambient conditions in the VFD, potentially offering industrial scaling up of production of full color carbon dots.Full Tex
Infrared studies of ortho-para conversion at Cl-atom and H-atom impurity centers in cryogenic solid hydrogen
No full textWe report infrared spectroscopic studies of H₂ ortho-para (o/p) conversion in solid hydrogen doped with Clatoms at 2 K while the Cl+H₂(v=1)→HCl+H infrared-induced chemical reaction is occurring. The Cl-atom doped hydrogen crystals are synthesized using 355 nm in situ photodissociation of Cl₂ precursor molecules. For hydrogen solids with high ortho-H₂ fractional concentrations (Xo=0.55), the o/p conversion kinetics is dominated by Cl-atom catalyzed conversion with a catalyzed conversion rate constant Kcc=1.16(11) min⁻¹ and the process is rate-limited by ortho-H₂ quantum diffusion. For hydrogen crystals with low ortho-H₂ concentrations (Xo=0.03), single-exponential decay of the ortho-H₂ concentration with time is observed which is attributed to H-atom catalyzed o/p conversion by the H-atoms produced during the infrared-induced Cl+H₂ reaction. The measured H-atom catalyzed o/p conversion kinetics indicates the H-atoms are mobile under these conditions in agreement with previous ESR measurements.This work was sponsored in part by the Chemistry Division of the US National Science Foundation (CHE 03-16268, CHE 08-48330)
Thin Film Mechano-Energy Induced Slicing of Carbon Nanotubes under Flow
No full textControlling the length of CNTs is important for their applications. As-prepared CNTs are typically nonuniform in length and are entangled, but for applications in electronics and biomedical research in particular, specific lengths are desirable; this has attracted intensified research efforts. We have developed a versatile thin film microfluidic method, which is high in green chemistry metrics, for controlled disentangling and slicing both single-walled CNTs and multiwalled CNTs. The method uses the mechanoenergy generated in a biphasic immiscible mixture of water and o-xylene in a titled vortex fluidic device (VFD) operating at ambient temperature, without the need for using surfactants or other axillary reagents and without the need for applying external fields. Importantly, this simple method can achieve a yield of 93% under continuous flow conditions. The high shear in the dynamic thin film in the VFD is also effective for such processing under continuous flow conditions, such that the method is scalable.No Full Tex
Open access self-archiving: An author study
No full textThis, our second author international, cross-disciplinary study on open access had 1296 respondents. Its focus was on self-archiving. Almost half (49%) of the respondent population have self-archived at least one article during the last three years. Use of institutional repositories for this purpose has doubled and usage has increased by almost 60% for subject-based repositories. Self-archiving activity is greatest amongst those who publish the largest number of papers. There is still a substantial proportion of authors unaware of the possibility of providing open access to their work by self-archiving. Of the authors who have not yet self-archived any articles, 71% remain unaware of the option. With 49% of the author population having self-archived in some way, this means that 36% of the total author population (71% of the remaining 51%), has not yet been appraised of this way of providing open access. Authors have frequently expressed reluctance to self-archive because of the perceived time required and possible technical difficulties in carrying out this activity, yet findings here show that only 20% of authors found some degree of difficulty with the first act of depositing an article in a repository, and that this dropped to 9% for subsequent deposits. Another author worry is about infringing agreed copyright agreements with publishers, yet only 10% of authors currently know of the SHERPA/RoMEO list of publisher permissions policies with respect to self-archiving, where clear guidance as to what a publisher permits is provided. Where it is not known if permission is required, however, authors are not seeking it and are self-archiving without it. Communicating their results to peers remains the primary reason for scholars publishing their work; in other words,
researchers publish to have an impact on their field. The vast majority of authors (81%) would willingly comply with a mandate from their employer or research funder to deposit copies of their articles in an institutional or subject-based repository. A further 13% would comply reluctantly; 5% would not comply with such a mandate
Progress of international hydrogen production network for the thermochemical Cu–Cl cycle
No full textThis paper presents recent advances by an international team which is developing the thermochemical copper–chlorine (Cu–Cl) cycle for hydrogen production. Development of the Cu–Cl cycle has been pursued by several countries within the framework of the Generation IV International Forum (GIF) for hydrogen production with the next generation of nuclear reactors. Due to its lower temperature requirements in comparison with other thermochemical cycles, the Cu–Cl cycle is particularly well matched with Canada's Generation IV reactor, SCWR (Super-Critical Water Reactor), as well as other heat sources such as solar energy or industrial waste heat. In this paper, recent developments of the Cu–Cl cycle are presented, specifically involving unit operation experiments, corrosion resistant materials and system integration.Atomic Energy of Canada LimitedOntario Research Excellence FundNatural Sciences and Engineering Research Council of CanadaUniversity Network of Excellence in Nuclear Engineering (UNENE)Canada Research Chairs progra
Lewis-Base Adducts of Main Group 1 Metal Compounds. IV. Synthesis and Structure of the XLiL3 System (X = Cl, Br, I, L = 4-t-Butylpyridine, and X = I, L = Quinoline)
No full textComplexes [XLiL3], X = Cl , Br, I; L = 4-t-butylpyridine, (1)-(3) have been synthesized by recrystallization of the anhydrous lithium halide from the parent base, and characterized structurally by single-crystal X-ray structure determination. (1) and (2) are isomorphous (monoclinic, P21), a ≈ 11.8, b ≈ 12.1, c ≈ 11.8 Ǻ, β 120°, Z 2 (R 0.051, 0.040 for No 1491, 1499 'observed' reflections); (3) is orthorhombic, Pbca, a 22.119(10), b 21.108(10), c 12.845(10) Ǻ, Z 8, R 0.067 for No 967. (1)- (3) are all pseudo- trigonal and contain four-coordinate XLiN3 arrays [Li-X, 2.33(1); 2.53(1); 2.76(4) Ǻ; Li-N, 2.03(1)-2.11(1); 2.04(1)-2.09(2); 2.03(4)-2.07(4)Ǻ]. Similar data are also recorded for X = I, L = quinoline (4)[monoclinic, P21/c, a 15.684(6), b 7.693(4), c 26.758(12) Ǻ,β 107.71(3)°, Z 4; R 0.072, No 3096; Li-I, 2.78(2); Li-N, 2.08(2)- 2.13(2)Ǻ]. While a close parallel may be drawn between the similarity of the chemistry of lithium(I) and copper(I) in respect of (1)-(3), (4) is unusual being the first XML3 derivative for a quinoline -type ligand; it is a monoquinoline solvate. </jats:p
Crystal structure of chlorobis(thiourea)mercury(II) chloride
No full textThe crystal structure of the title compound, has been determined by single-crystal X-ray diffraction by conventional heavy-atom methods, and refined by block-diagonal least-squares to R 0簸 for 359 visually estimated reflections. Crystals are orthorhombic, space group Pmmn, a= 6紴 ᠰ簱, b= 12緶 ᠰ簲, c= 5繱 ᠰ簱 Ż Z= 2.The mercury atom is co-ordinated in an unusual approximately trigonal planar conformation by the two equivalent thiourea sulphur atoms and a chlorine atom (Hg-S 2紲 ᠰ簱, Hg-Cl 2絷 ᠰ簱 Ż S-Hg-Cl 110縠ᠰ粬 S-Hg-S 138素ᠰ粰). The other ionic chlorine atom lies normal to this plane, between and equidistant from a pair of mercury atoms at 3粲 Ů The thiourea molecules and the mercury and co-ordinated chlorine atoms are coplanar (Hg-S-C 110簠ᠰ繰); their intramolecular geometry is as expected.No Full Tex
ŻYCIE UKRYTE W SŁOWIE. "BEKSIŃSCY. PORTRET PODWÓJNY" MAGDALENY GRZEBIAŁKOWSKIEJ W ŚWIETLE POSTSTRUKTURALIZMU
No full textLife Hidden in Words. Magdalena Grzebiałkowska\u27s "Beksińscy. Portret podwójny" and Poststructuralism
The article analyzes Magdalena Grzebiałkowska\u27s biographical "Beksińscy. Portret podwójny" which focuses on the lives of Zdzisław Beksiński and Tomasz Beksiński. The author looks at the construction of the biography and its relationship to poststructuralism, which allows for an appreciation of the literary features of the book. He points to how the specificity of the content, language, a mode of narration in Grzebiałkowska\u27s book make it a full-fledged literary work itself. As such the book departs from a typical biographical scheme. Juxtaposing the book with poststructural ideas leads to the reconsideration of the role of the author in the process of shaping of a biographical narrative
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