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1.
Chem Commun (Camb) ; 56(88): 13623-13626, 2020 Nov 05.
Article in English | MEDLINE | ID: mdl-33057496

ABSTRACT

Transformations catalyzed by germanium are scarce, with examples mainly limited to widely catalyzed processes such as polymerisation of lactide and hydroboration of carbonyls. Reported is the first example of hydrophosphination using a germanium pre-catalyst, yielding anti-Markovnikov products when diphenylphosphine is reacted with styrenes or internal alkynes at room temperature.

2.
Chem Commun (Camb) ; 54(74): 10443-10446, 2018 Sep 13.
Article in English | MEDLINE | ID: mdl-30152503

ABSTRACT

A catalytic hydrophosphination route to 1,1-diphosphines is yet to be reported: these narrow bite angle pro-ligands have been used to great effect as ligands in homogeneous catalysis. We herein demonstrate that terminal alkynes readily undergo double hydrophosphination with HPPh2 and catalytic potassium hexamethyldisilazane (KHMDS) to generate 1,1-diphosphines. A change to H2PPh leads to the formation of P,P-divinyl phosphines.

3.
Sci Rep ; 8(1): 1676, 2018 01 26.
Article in English | MEDLINE | ID: mdl-29374211

ABSTRACT

Type III solar radio bursts are the Sun's most intense and frequent nonthermal radio emissions. They involve two critical problems in astrophysics, plasma physics, and space physics: how collective processes produce nonthermal radiation and how magnetic reconnection occurs and changes magnetic energy into kinetic energy. Here magnetic reconnection events are identified definitively in Solar Dynamics Observatory UV-EUV data, with strong upward and downward pairs of jets, current sheets, and cusp-like geometries on top of time-varying magnetic loops, and strong outflows along pairs of open magnetic field lines. Type III bursts imaged by the Murchison Widefield Array and detected by the Learmonth radiospectrograph and STEREO B spacecraft are demonstrated to be in very good temporal and spatial coincidence with specific reconnection events and with bursts of X-rays detected by the RHESSI spacecraft. The reconnection sites are low, near heights of 5-10 Mm. These images and event timings provide the long-desired direct evidence that semi-relativistic electrons energized in magnetic reconnection regions produce type III radio bursts. Not all the observed reconnection events produce X-ray events or coronal or interplanetary type III bursts; thus different special conditions exist for electrons leaving reconnection regions to produce observable radio, EUV, UV, and X-ray bursts.

4.
Dalton Trans ; 46(14): 4483-4498, 2017 Apr 05.
Article in English | MEDLINE | ID: mdl-28262881

ABSTRACT

Although ß-diketiminate complexes have been widely explored in stoichiometric studies, their use as catalysts is largely underdeveloped. With growing interest in the catalytic activity of complexes of the first row transition metals, primarily due to the untapped potential of such metal centers, along with the growing global focus on sustainable chemistry with earth abundant metals, this Perspective focuses on the use of ß-diketiminate complexes of the first row transition metals as catalysts for the synthesis of small organic molecules.

5.
J Sep Sci ; 39(13): 2537-43, 2016 Jul.
Article in English | MEDLINE | ID: mdl-27159197

ABSTRACT

Measurement of contamination of marine and naval diesel fuels (arising from product mixing or adulteration) with biodiesel or fatty acid methyl esters can be problematic, especially at very low levels. A suitable solution for this task for trace amounts of individual fatty acid methyl esters with resolution and quantification can be achieved by using a multidimensional gas chromatographic approach with electron and chemical ionization mass spectrometric detection. A unique column set comprising a 100 m methyl-siloxane nonpolar first dimension column and high-temperature ionic liquid column in the second dimension enabled identification of individual fatty acid methyl esters at below the lowest concentrations required to be reported in a diesel fuel matrix. Detection limits for individual fatty acid methyl esters compounds ranged from 0.5 to 5.0 mg/L, with excellent linearity up to 5000 mg/L and repeatability of the method from 1.3 to 3.2%. The method was applied to the analysis of diesel fuel samples with suspected biodiesel contamination. Contamination at 568 mg/L was calculated for an unknown sample and interpretation of the results permitted the determination of a likely source of the contamination.

6.
Dalton Trans ; 44(22): 10253-8, 2015 Jun 14.
Article in English | MEDLINE | ID: mdl-25958825

ABSTRACT

We report a rare example of the malonamide functionality being used as a ligand in copper catalysis. We have ligated a homologous series of these O,O-chelating architectures to copper, investigated their structure and exploited them in azide-alkyne cycloaddition reactions for the step-growth synthesis of oligo(triazoles) and in the synthesis of small organic azoles.

7.
Chem Commun (Camb) ; 50(81): 12109-11, 2014 Oct 18.
Article in English | MEDLINE | ID: mdl-25168587

ABSTRACT

Phosphines are fundamentally important to the fine chemicals, pharmaceutical and agrochemical industries. Reported is the first example of alkene hydrophosphination using a designed iron pre-catalyst which yields the anti-Markovnikov products in high yield at room temperature. The phosphine products are excellent pro-ligands for Fe-catalyzed Negishi cross-coupling.

8.
Chem Commun (Camb) ; 50(73): 10665-8, 2014 Sep 21.
Article in English | MEDLINE | ID: mdl-25078455

ABSTRACT

A new amide monomer for step growth polymerisation is reported: the chemistry exploits a bulky malonamide for the synthesis of polyesters and polyamides. No additives are needed and the only by-product, an amine, can be recycled.

9.
Psychol Rep ; 88(3 Pt 1): 701-6, 2001 Jun.
Article in English | MEDLINE | ID: mdl-11508006

ABSTRACT

Measures of reported self-confidence in performing financial analysis by 59 professional male analysts, 31 born between 1946 and 1964 and 28 born between 1965 and 1976, were investigated and reported. Self-confidence in one's ability is important in the securities industry because it affects recommendations and decisions to buy, sell, and hold securities. The respondents analyzed a set of multiyear corporate financial statements and reported their self-confidence in six separate financial areas. Data from the 59 male financial analysts were tallied and analyzed using both univariate and multivariate statistical tests. Rated self-confidence was not significantly different for the younger and the older men. These results are not consistent with a similar prior study of female analysts in which younger women showed significantly higher self-confidence than older women.


Subject(s)
Aging/psychology , Financial Audit , Financial Management , Self Efficacy , Adult , Female , Humans , Male , Middle Aged , Sex Factors
10.
J Speech Hear Res ; 38(2): 280-8, 1995 Apr.
Article in English | MEDLINE | ID: mdl-7596094

ABSTRACT

A rating instrument is described that can be used to assess the results of stuttering treatments. The instrument is designed for use with naive listeners. It yields a comprehensive and detailed description of the speech quality in terms of articulation, phonation, pitch, and loudness; in addition, it includes a naturalness scale. Analysis of ratings obtained with the instrument show that naturalness is a multidimensional characteristic. Moreover, the speech characteristics that determine the naturalness ratings appear to be different pretreatment, posttreatment, and at follow-up treatment. The psychometric characteristics of the instrument are analyzed in detail. It is concluded that mixing of samples of stutterers and nonstutterers in one rating experiment may artificially inflate the reliability of the ratings. Also, ratings on equal-appearing interval scales cannot be interpreted in an absolute sense. Solutions for this methodological problem are suggested.


Subject(s)
Severity of Illness Index , Stuttering/diagnosis , Stuttering/therapy , Adolescent , Adult , Humans , Male , Middle Aged , Speech Therapy , Voice Quality
11.
Aviat Space Environ Med ; 59(12): 1190-2, 1988 Dec.
Article in English | MEDLINE | ID: mdl-3240222

ABSTRACT

Thermal evaluation of aircrew clothing in the field usually involves conditions which make it difficult to distinguish clothing effects from other, confounding factors. This paper reports a field study designed to solve this problem. The question concerned possible heat stress effects caused by adding an oxygen mask, an anti-g suit, or both to the usual clothing worn by pilots of OV-10 (twin turboprop) aircraft during 20 hot-weather flights (actual experimental temperatures of Tdb = 28-38 degrees C, rh = 18-20%). The four test ensembles were flown simultaneously, allowing side-by-side comparison to compensate for variations in flight profile and weather. Subjects (n = 10) encountered noticeable heat stress in flight, with rectal temperature = 37.4-37.6 degrees C, skin temperature = 35.0-35.5 degrees C, and weight losses = 2.1-2.4 kg. There were no measurable differences among the four clothing outfits, indicating that the anti-g suit does not present a heat stress problem. The mask and anti-g suit did contribute to aircrew discomfort as their impermeable materials prevented evaporation of sweat and caused 100% skin wetting in covered areas. Under these dry, desert conditions, the body was apparently able to compensate for the loss of evaporative surface area.


Subject(s)
Masks/standards , Military Personnel , Protective Clothing/standards , Space Flight , Gravitation , Heat Exhaustion/etiology , Humans , Risk Factors
12.
J Speech Hear Res ; 23(3): 539-45, 1980 Sep.
Article in English | MEDLINE | ID: mdl-7421157

ABSTRACT

The possibility of a genetic component to the severity of stuttering was investigated using data on 184 adult stutters and their families. Frequency of stuttering during a pre-treatment oral reading task was used as the severity measure for each of the index cases. Information on whether or not a relative ever stuttered was obtained on all first degree relatives. The family data variables, including sex and exact relationship, combined with birthdate and sex of index case were used in three types of analyses: multiple regressions, AID regressions, and stepwise regressions. None of the variables tested, including stuttering among first degree relatives, was a predictor of severity of stuttering in the index case. We conclude that this measure of severity is not related to the genetic factors which predispose to stuttering.


Subject(s)
Stuttering/genetics , Adolescent , Adult , Aged , Female , Humans , Male , Middle Aged , Pedigree , Regression Analysis , Stuttering/diagnosis
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