106 research outputs found
Formation and Properties of Some Uretediones
ofmann (Ber., 4, 246. 1871.) found that triethylphosphine served as a catalyst to cause the polymerization of phenyl isocyanate to a dimer which he designated as diphenyl diisocyanate. Staudinger ( Die Ketene , Enke, Stuttgart, 1912, p. 126.) regarded this product as a four atomic ring derivative. It has now been found that triethylphosphine polymerizes a number of substituted phenylisocyanates, such as λ- and ÎČ-naphthyl isocyanates, and p-xenyl isocyanate. These products which have more recently been listed as derivatives of uretedione, react with aliphatic amines to produce substituted biurets
Action of Thionyl Chloride on Urethanes (Abstract)
Raiford and Shelton [J. Org. Chem., 4, 207 (1939)] found that hot pyridine causes 2-carbophenoxyamino-4-methy 1-6-bromophenyl p-tolylsulfonate to lose phenol and give a condensation product which was found to be a 1,3- derivative of uretedione (uretidone). This type of derivative was also obtained by Warren and Wilson [Ber., 68, 957 (1935) J by the action of thionyl chloride on phenylurethane. But it has now been found that the last-named reaction is specific for phenylure thane. When the phenyl radical contains a negative substituent, thionyl chloride causes no action after five hours refluxing. If the substituent is alkyl the treatment causes tar formation, from which nothing definite could be isolated. Ethyl and n-butyl carbamates react with thionyl chloride to give the corresponding esters of allophanic acid and small amounts of cyanuric acid. Under the same treatment 2-naphthylurethane undergoes chlorination to give the 1-chloro derivative, while the 1-naphthyl compound gives the 4-chloro derivative
Labor and delivery service use: indigenous womenâs preference and the health sector response in the Chiapas Highlands of Mexico
First Results for the Beam Commissioning of the CERN Multi-Turn Extraction
The Multi-Turn Extraction (MTE), a new type of extraction based on beam trapping inside stable islands in horizontal phase space, has been commissioned during the 2008 run of the CERN Proton Synchrotron. Both singleand multi-bunch beams with a total intensity up to 1.4 1013 protons have been extracted with efficiencies up to 98%. Furthermore, injection tests in the CERN Super Proton Synchrotron were performed, with the beam then accelerated and extracted to produce neutrinos for the CERN Neutrino-to-Gran Sasso experiments. The results of the extensive measurement campaign are presented and discussed in detail
Evidence of a dibaryon spectrum in coherent Ï0Ï0d photoproduction at forward deuteron angles
The coherent reaction, was studied with the BGOOD experiment at ELSA from threshold to a centre-of-mass energy of 2850 MeV. A full kinematic reconstruction was made, with final state deuterons identified in the forward spectrometer and decays in the central BGO Rugby Ball. The strength of the differential cross section exceeds what can be described by models of coherent photoproduction and instead supports the three isoscalar dibaryon candidates reported by the ELPH collaboration at 2.38, 2.47 and 2.63 GeV/c2. A low mass enhancement in the invariant mass is also observed at the
â
centre-of-mass energy which is consistent with the ABC effect. At higher centre-of-mass energies, a narrow peak in the invariant mass at 2114 MeV/c2 with a width of 20 MeV/c2 supports a sequential two-dibaryon decay mechanism
Photoproduction of K+ Î(1405) â K+ Ï0 ÎŁ0 extending to forward angles and low momentum transfer
K+ Lambda (1405) photoproduction has been studied at the BGOOD experiment via the all neutral decay, Lambda(1405)-> Sigma0 Pi0. The unique BGOOD experimental setup allows both the cross section and
invariant mass Lamba(1405) distribution (line shape) to be measured over a broad K+ polar angle range, extending to extreme forward K+ angles unattainable at previous experiments.
Evidence is provided for the role of a triangle singularity driven by the N*(2030)â
resonance, which appears to contribute significantly to K+Lambda(1405)
photoproduction. This is observed in the integrated cross section which was determined with unprecedented energy resolution and supported by the angular distributions. The measured line shape is also in agreement with the previous results of CLAS and ANKE, and is consistent with two poles derived in ÏPT based models
Measurement of the Îł n â K0 0 differential cross section over the Kâ threshold
The differential cross section for the quasi-free photoproduction reaction gamma(n)-> K-0 Sigma(0) was measured at BGOOD at ELSA from threshold to a centre-of-mass energy of 2400 MeV. Close to threshold the results are consistent with existing data and are in agreement with partial wave analysis solutions over the full measured energy range, with a large coupling to the Delta(1900)1/2(-) evident. This is the first dataset covering the K* threshold region, where there are model predictions of dynamically generated vector meson-baryon resonance contributions
Incorporating Genomics and Bioinformatics across the Life Sciences Curriculum
Undergraduate life sciences education needs an overhaul, as clearly described in the National Research Council of the National Academiesâ publication BIO 2010: Transforming Undergraduate Education for Future Research Biologists. Among BIO 2010âs top recommendations is the need to involve students in working with real data and tools that reflect the nature of life sciences research in the 21st century [1]. Education research studies support the importance of utilizing primary literature, designing and implementing experiments, and analyzing results in the context of a bona fide scientific question [1â12] in cultivating the analytical skills necessary to become a scientist. Incorporating these basic scientific methodologies in undergraduate education leads to increased undergraduate and post-graduate retention in the sciences [13â16]. Toward this end, many undergraduate teaching organizations offer training and suggestions for faculty to update and improve their teaching approaches to help students learn as scientists, through design and discovery (e.g., Council of Undergraduate Research [www.cur.org] and Project Kaleidoscope [ www.pkal.org])
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