Structure and physical properties of aluminium alkoxides: 1. Mass spectra of aluminium isopropoxides

6-(Furan-2-yl)-2,4-tetrakis(dimethylamino)-1-aza-2λ5, 4λ5-diphosphirine (2) and 6-(N-pyrrolidinyl)-2,4-tetrakis(dimethylamino)-1-aza-2λ5, 45-diphosphirine (3) were prepared by reacting 1,1,3,3-tetrakis(dimethylamino)-1 λ5,3 λ5-diphosphete with 2-cyanofuran, and N-cyanopyrrolidine, respectively. 2 and 3 are characterized by their physical properties, NMR, IR, and mass spectra. In 2 two 6J(PH) long range coupling constants could be identified.

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Evidence for Biosynthetical Equivalence of the Epimeric Isoleucine Residues in Angolide

Canadian Journal of Biochemistry ◽

10.1139/o72-058 ◽

1972 ◽

Vol 50 (4) ◽

pp. 428-439 ◽

Cited By ~ 5

Author(s):

R. O. Okotore ◽

D. W. Russell

Keyword(s):

Amino Acid ◽

Physical Properties ◽

Acid Hydrolysis ◽

Column Chromatography ◽

Mass Spectra ◽

Mathematical Treatment ◽

Amino Acid Residues ◽

Analytical Results ◽

Cyclic Intermediate

Pithomyces sacchari was grown on media containing L-valine. Instead of the metabolite angolide (cyclo-L-α-hydroxyisovaleryl1-erythro-L-isoleucyl2-L-α-hydroxyisovaleryl3-threo-D-isoleucyl4), synthesized on un-supplemented media, it produced a mixture with very similar physical properties. Acid hydrolysis liberated erythro-L- and threo-D-isoleucines (1:1), and DL-valine in amounts proportional to the exogenous valine concentration; L-α-hydroxyisovaleric acid was the only other component. Radioactivity from L-valine-U-14C was incorporated without dilution into valine, and with extensive dilution into the hydroxy acid.Partial fractionation of the mixture was achieved by column chromatography. Mass spectra of two fractions, containing different proportions of valine, were compared with the spectrum of angolide. A simple mathematical treatment showed that the fractions contained angolide, its divaline homologue, and a homologue with only one isoleucine replaced by valine. This must be a 1: 1 mixture of the two possible isomers, since any deviation from this ratio is inconsistent with the analytical results. It follows that the erythro-L- and the threo-D-isoleucine residues of angolide are equivalent with respect to their replacement by valine. It is inferred that angolide biosynthesis involves a cyclic intermediate containing both amino acid residues in the L configuration.

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Physical Properties of Cometary Dust

International Astronomical Union Colloquium ◽

10.1017/s0252921100012811 ◽

1991 ◽

Vol 116 (2) ◽

pp. 1043-1073 ◽

Cited By ~ 34

Author(s):

J.A.M. McDonnell ◽

P.L. Lamy ◽

G.S. Pankiewicz

Keyword(s):

Physical Properties ◽

Mass Spectra ◽

Size Range ◽

Dust Production ◽

Full Size ◽

Cometary Dust ◽

Dust Coma ◽

Comet Halley ◽

Complete Process

AbstractPrior to the 1986 apparition of comet Halley, all attempts to determine the physical properties of cometary dust were limited to remote observations and the analysis of various particles captured by the Earth’s atmosphere. The in situ measurements made by the three spacecraft that passed within 10,000 km of the nucleus provided the first opportunity to investigate both the full size-range of particles and the complete process of dust production. Information on composition is derived through mass spectra and the scattering and emission of light from the grains, whilst the dynamics of the dust coma can be modeled from the three separate sets of measurements made over a period of eight days.

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Structure and physical properties of aluminium alkoxides. Part II: Changes in physical properties of liquid aluminium isopropoxide during storage

Recueil des Travaux Chimiques des Pays-Bas ◽

10.1002/recl.19700890210 ◽

2010 ◽

Vol 89 (2) ◽

pp. 175-185 ◽

Cited By ~ 12

Author(s):

W. Fieggen ◽

H. Gerding

Keyword(s):

Physical Properties ◽

Aluminium Isopropoxide ◽

Liquid Aluminium ◽

Aluminium Alkoxides

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Contrasting physical properties of black carbon in urban Beijing between winter and summer

Atmospheric Chemistry and Physics ◽

10.5194/acp-19-6749-2019 ◽

2019 ◽

Vol 19 (10) ◽

pp. 6749-6769 ◽

Cited By ~ 30

Author(s):

Dantong Liu ◽

Rutambhara Joshi ◽

Junfeng Wang ◽

Chenjie Yu ◽

James D. Allan ◽

...

Keyword(s):

Physical Properties ◽

Human Health ◽

Black Carbon ◽

Mass Spectra ◽

Industrial Sector ◽

Cold Season ◽

Absorption Efficiency ◽

Urban Environments ◽

Pollution Level ◽

Core Diameter

Abstract. Black carbon (BC) is known to have major impacts on both human health and climate. The populated megacity represents the most complex anthropogenic BC emissions where the sources and related impacts are very uncertain. This study provides source attribution and characterization of BC in the Beijing urban environment during the joint UK–China APHH (Air Pollution and Human Health) project, in both winter (November–December 2016) and summer (May–June 2017). The size-resolved mixing state of BC-containing particles was characterized by a single-particle soot photometer (SP2) and their mass spectra was measured by a soot particle aerosol mass spectrometer (SP-AMS). The refractory BC (rBC) mass loading was around a factor of 2 higher in winter relative to summer, and more variable coatings were present, likely as a result of additional surface emissions from the residential sector and favourable condensation in the cold season. The characteristics of the BC were relatively independent of air mass direction in summer, whereas in winter air masses from the Northern Plateau were considerably cleaner and contained less-coated and smaller BC, but the BC from the Southern Plateau had the largest core size and coatings. We compare two online source apportionment methods using simultaneous measurements made by the SP2, which measures physical properties of BC, and the chemical approach using the positive matrix factorization (PMF) of mass spectra from the SP-AMS for the first time. A method is proposed to isolate the BC from the transportation sector using a mode of small BC particles (core diameter Dc<0.18 µm and coating thickness ct < 50 nm). This mode of BC highly correlated with NOx concentration in both seasons (∼14 ng m−3 BC ppb−1 NOx) and corresponded with the morning traffic rush hour, contributing about 30 % and 40 % of the total rBC mass (35 % and 55 % in number) in winter and summer respectively. The BC from coal burning or biomass burning was characterized by moderate coatings (ct = 50–200 nm) contributing ∼20 %–25 % of rBC mass. Large uncoated BC particles (Dc>0.18 µm and ct < 50 nm) were more likely to be contributed by coal combustion, as these particles were not present in urban London. This mode was present in Beijing in both winter (∼30 %–40 % rBC mass) and summer (∼40 % rBC mass) but may be dominated by the residential and industrial sector respectively. The contribution of BC thickly coated with secondary species (ct > 200 nm) to the total rBC mass increased with pollution level in winter but was minor in summer. These large BC particles importantly enhanced the absorption efficiency at high pollution levels – in winter when PM1 > 100 µg m−3 or BC > 2 µg m−3, the absorption efficiency of BC increased by 25 %–70 %. The reduction of emissions of these large BC particles and the precursors of the associated secondary coating will be an effective way of mitigating the heating effect of BC in urban environments.

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Synthesis and Vibrational and Mass Spectra of (n-Bu)2Sn(O2PMe2)2, (n-Bu)2Sn(O2PMePh)2 and (n-Bu)2Sn(O2PPh2)2

Zeitschrift für Naturforschung B ◽

10.1515/znb-1995-0510 ◽

1995 ◽

Vol 50 (5) ◽

pp. 745-749 ◽

Cited By ~ 2

Author(s):

Abdel-Fattah Shihada

Keyword(s):

Physical Properties ◽

Vibrational Spectra ◽

Mass Spectra ◽

Base Peak ◽

Trans Position ◽

Octahedral Environment ◽

In Trans ◽

Fragmentation Processes

Abstract Di-n-butyltin dimethylphosphinate has been synthesized by the reaction of (n-Bu)2Sn(OCOCH3)2 with HO2PMe2 in benzene. The ractions of (n-Bu)2Sn(OCOCH3)2 with MePhPOCl and Ph2POCl in toluene have been used to prepare (n-Bu)2Sn(O2PMePh)2 and (n-Bu)2Sn(O2PPh2)2 respectively. On the basis of vibrational spectra and physical properties it is conclu ded that the title compounds are polymerized and the ligands function as O-P-O bridges between the tin atoms. The n-butyl groups are in trans position in the resulting octahedral environment around tin. Loss of n-butyl radicals and of the diorganophosphinate group from tin represent the main fragmentation processes in the El mass spectra of (n-Bu)2Sn(O2PRR′)2(RR′=Me2, MePh, Ph2). The mass spectra show Sn(O2PRR′)+ as the base peak.

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