41 resultados para Hine, Lewis
Resumo:
The preparation of chelated difluoroboron cations (DD)BF2+, where DD is a saturated polydentate tertiary-amine or polydentate aromatic ligand, has been systematically studied by using multinuclear solution and solid state nuclear magnetic resonance spectroscopy and fast atom bombardment mass spectrometry. Three new methods of synthesis of (DD)BF2+ cations are reported, and compared with the previous method of reacting a chelating donor with Et20.BF3. The methods most effective for aromatic donors such as 1,1O-phenanthroline are ineffective for saturated polydentate tertiary-amines like N,N,N' ,Nil ,Nil-pentamethyldiethylenetriamine. Polydentate tertiary-amine donors that form 5-membered rings upon bidentate chelation were found to chelate effectively when the BF2 source contained two leaving groups (a heavy halide and a Lewis base such as pyridine =pyr or isoxazole =ISOX), i.e., pyr.BF2X (X = CI or Br), ISOX.BF2X and (pyr)2BF2+. Those that would form 6membered rings upon chelation do not chelate by any of the four methods. Polydentate aromatic ligands chelate effectively when the BF2 source contained a weak Lewis base, e.g., ISOX.BF3, ISOX.BF2X and Et20.BF3. Bidentate chelation by polydentate tertiaryamine and aromatic donors leads to nmr parameters that are significantly different then their (D)2BF2+ relatives (D =monod~ntate t-amines or pyridines). The chelated haloboron cations (DD)BFCI+, and (DD)BFBr+ were generated from D.BFX2 adducts for all ligands that form BF2+ cations above. In addition, the (DD)BCI2+ and (DD)BBr2+ cations were formed from D.BX3 adducts by the chelating aromatic ligands, except for the aromatic ligand 1,8-bis(dimethylamino)naphthalene, which formed only the (DD)BF2+ cation, apparently due to its extreme steric hindrance. Chelation by a donor is a two-step reaction. For polydentate tertiary-amine ligands, the two rates appear to be very dependent on the two possible leaving groups on the central boron atom. The order of increasing ease of displacement for the donors was: pyr < Cl < Br < ISOX. The rate of chelation by polydentate aromatic ligands appears to be dependent on the displacement of the first ligand from the boron. The order of increasing ease of displacement for the donors was: pyr < CI < ISOX ~ Br < Et20.
Resumo:
Exchange reactions between molecular complexes and excess acid
or base are well known and have been extensively surveyed in the
literature(l). Since the exchange mechanism will, in some way
involve the breaking of the labile donor-acceptor bond, it follows
that a discussion of the factors relating to bonding in molecular complexes
will be relevant.
In general, a strong Lewis base and a strong Lewis acid form a
stable adduct provided that certain stereochemical requirements are
met.
A strong Lewis base has the following characteristics (1),(2)
(i) high electron density at the donor site.
(ii) a non-bonded electron pair which has a low ionization potential
(iii) electron donating substituents at the donor atom site.
(iv) facile approach of the site of the Lewis base to the
acceptor site as dictated by the steric hindrance of the
substituents.
Examples of typical Lewis bases are ethers, nitriles, ketones,
alcohols, amines and phosphines.
For a strong Lewis acid, the following properties are important:(
i) low electron density at the acceptor site.
(ii) electron withdrawing substituents. (iii) substituents which do not interfere with the close
approach of the Lewis base.
(iv) availability of a vacant orbital capable of accepting
the lone electron pair of the donor atom.
Examples of Lewis acids are the group III and IV halides such
(M=B, AI, Ga, In) and MX4 - (M=Si, Ge, Sn, Pb).
The relative bond strengths of molecular complexes have been
investigated by:-
(i)
(ii)
(iii)
(iv)
(v]
(vi)
dipole moment measurements (3).
shifts of the carbonyl peaks in the IIIR. (4) ,(5), (6) ..
NMR chemical shift data (4),(7),(8),(9).
D.V. and visible spectrophotometric shifts (10),(11).
equilibrium constant data (12), (13).
heats of dissociation and heats of reactions (l~),
(16), (17), (18), (19).
Many experiments have bben carried out on boron trihalides in
order to determine their relative acid strengths. Using pyridine,
nitrobenzene, acetonitrile and trimethylamine as reference Lewis
bases, it was found that the acid strength varied in order:RBx3 >
BC1
3 >BF 3
• For the acetonitrile-boron trihalide and trimethylamine
boron trihalide complexes in nitrobenzene, an-NMR study (7) showed
that the shift to lower field was. greatest for the BB~3 adduct ~n~
smallest for the BF 3 which is in agreement with the acid strengths. If electronegativities of the substituents were the only
important effect, and since c~ Br ,one would expect
the electron density at the boron nucleus to vary as BF3
Resumo:
Genetic chimeras made by aggregating early mouse embryos have many uses in developmental biology and have also provided insights into embryonic growth regulation. There is an indication that the embryo can regulate for an increase in size because although aggregation chimeras are twice as big as normal embryos when made, they are born of normal size. Upward regula..... tion of size reduced embryos is also possible. Half embryos made by the isolation or destruction of one of the blastomeres of a 2-cell embryo are also born of normal size. Little is known about the timing or the mechanism of this size regulation. In this study, the timing of size regulation in double and half embryos was clearly established by comparison of cell numbers derived from serial reconstruction of light microscope sections of control and experimental embryos. It was shown that size regulation in double embryos occurred around 6dl6h and in half embryos by 7dOh. Size regulation occurred in all tissues at the same time indicating a single control mechanism for the entire embryo. More detailed examination of the growth of double embryos revealed that size regulation occurred by alteration in cell cycle length~ No excessive cell death was found in double embryos compared to the controls and continuous labelling with [3H] thymidine showed no large non-dividing cell population in double embryos. However, a comparison of the mitotic index of double and control embryos after colcemid treatment, revealed a large difference between the two around 5dl6h to 6d16h. During this period, control embryos underwent a proliferative burst not shown by the double embryos. The mechanism for cell cycle control is not clear; it may be intrinsic to the embryo or determined by the uterine environment. Evidence was found suggesting that differentiation in the postimplantation embryo was cell number dependent. The timing of differentiative events was examined in half, double and control embryos. Proamnion formation, which occurs prior to size regulation, occurs at the same cell number but at different times in the three groups of embryos. However mesoderm which appears after size regulation was seen at the same time in all grollps of embryos.
Resumo:
Recent research on the sources of cognitive competence in infancy and early childhood has highlighted the role of social and emotional factors (for example, Lewis, 1993b). Exploring the roots of competence requires a longitudinal and multivariate approach. To deal with the resulting complexity, potentially integrative theoretical constructs are required. One logical candidate is self-regulation. Three key developmental questions were the focus of this investigation. 1) Does infant self-regulation (attentional, emotional, and social) predict preschool cognitive competence? 2) Does infant self-regulation predict preschool self-regulation? 3) Does preschool self-regulation predict concurrent preschool cognitive competence? One hundred preschoolers (46 females, 54 males; mean age = 5 years, 11 months) who had participated at 9- and/ or 12-months of age in an object permanence task were recruited to participate in this longitudinal investigation. Each subject completed four scales of the WPPSI-R and two social cognitive tasks. Parents completed questionnaires about their preschoolers' regulatory behaviours (Achenbach's Child Behavior Checklist [1991] and selected items from Eisenberg et ale [1993] and Derryberry & Rothbart [1988]). Separate behavioural coding systems were developed to capture regulatory capabilities in infancy (from the object permanence task) and preschool (from the WPPSIR Block Design). Overall, correlational and multiple regression results offered strong affirmative answers to the three key questions (R's = .30 to .38), using the behavioural observations of self-regulation. Behavioural regulation at preschool substantially predicted parental reports of regulation, but the latter variables did not predict preschool competence. Infant selfregulation and preschool regulation made statistically independent contributions to competence, even though regulation at Time 1 and Time 2 ii were substantially related. The results are interpreted as supporting a developmental pathway in which well-regulated infants more readily acquire both expertise and more sophisticated regulatory skills. Future research should address the origins of these skills earlier in infancy, and the social contexts that generate them and support them during the intervening years.
Resumo:
The 3700 A - 3000 A absorption spectra of CH3CHO and its isotopic compounds such as CH3CDO, CD3CHO and CD3CDO were studied in the gas phase at room temperature and low temperatures. The low resolution spectra of the compounds were recorded by a 1.5 m Baush and Lomb grating spectrograph. The high resolution spectra were recorded by a Ebert spectrograph with the Echelle grating and the holographic grating separately. The multiple reflection cells were used to achieve the long path length. The pressure-path length used for the absorption spectrum of CH 3CHO was up to 100 mm Hg )( 91 . 43mo The emission spectrum and the excitation spectrum of CH3CHO were also recorded in this research. The calculated satellite band patterns \vhich were ob-tailied by the method of Lewis were used to compare with the observed near UV absorption spectrum of acetaldehyde. These calculated satellite band patterns belonged to two cases: namely, the barriers-in-phase case and the barriers- out-of-phase case. Each of the calculated patterns corresponded to a stable conformation of acetaldehyde in the excited state . The comparisons showed that the patterns in the observed absorption spectra corresponded to the H-H eclipsed conformations of acetaldehyde in the excited state . The least squares fitting analysis showed that the barrier heights in the excited state were higher than in the ground state. Finally, the isotopic shifts for the isotopic compounds of acetaldehyde were compared to the compounds with the similar deuterium substitution.
Resumo:
Boron trihalide and mixed boron trihalide adducts of trimethylamine have been prepared, and characterized by proton and fluorine N.M.R. spectroscopy. The acceptor power of the boron trihalides was seen to increase in the order BF3 < BC13 < BBr3 < BI3, corroborating previous evidence. The mixed boron trihalides had intermediate Lewis acidities. Solution reactions between adducts and free boron trihalides rapidly led to the formation of mixed adducts when the free boron trihalide is a stronger Lewis acid than that in the adduct. A slower reaction is observed when the free BX3 is a weaker Lewis aoid than that complexed. The mechanism of halogen exchange leading to the mixed (CH3)3NBX3 adducts was investigated. 10B labelling experiments precluded B-N bond rupture as a possible mechanism in solution; results are discussed in terms of halogen-bridged intermediates. Pre-ionization may be important for some systems. At higher temperatures, during gas phase reactions,B-N coordinate bond rupture may be the initial step of reaction. Two mixed adduots, namely (CH3)3NBClBr2 and (CH3)3NBHOIBr were prepared and characterized by Mass Spectrometry
Resumo:
Fifty-six percent of Canadians, 20 years of age and older, are inactive (Canadian Community Health Survey, 200012001). Research has indicated that one of the most dramatic declines in population physical activity occurs between adolescence and young adulthood (Melina, 2001; Stephens, Jacobs, & White, 1985), a time when individuals this age are entering or attending college or university. Colleges and universities have generally been seen as environments where physical activity and sport can be promoted and accommodated as a result of the available resources and facilities (Archer, Probert, & Gagne, 1987; Suminski, Petosa, Utter, & Zhang, 2002). Intramural sports, one of the most common campus recreational sports options available for post-secondary students, enable students to participate in activities that are suited for different levels of ability and interest (Lewis, Jones, Lamke, & Dunn, 1998). While intramural sports can positively affect the physical activity levels and sport participation rates of post-secondary students, their true value lies in their ability to encourage sport participation after school ends and during the post-school lives of graduates (Forrester, Ross, Geary, & Hall, 2007). This study used the Sport Commitment Model (Scanlan et aI., 1993a) and the Theory of Planned Behaviour (Ajzen, 1991) with post secondary intramural volleyball participants in an effort to examine students' commitment to intramural sport and 1 intentions to participate in intramural sports. More specifically, the research objectives of this study were to: (1.) test the Sport Commitment Model with a sample of postsecondary intramural sport participants(2.) determine the utility of the sixth construct, social support, in explaining the sport commitment of post-secondary intramural sport participants; (3.) determine if there are any significant differences in the six constructs of IV the SCM and sport commitment between: gender, level of competition (competitive A vs. B), and number of different intramural sports played; (4.) determine if there are any significant differences between sport commitment levels and constructs from the Theory of Planned Behaviour (attitudes, subjective norms, perceived behavioural control, and intentions); (5.) determine the relationship between sport commitment and intention to continue participation in intramural volleyball, continue participating in intramurals and continuing participating in sport and physical activity after graduation; and (6.) determine if the level of sport commitment changes the relationship between the constructs from the Theory of Planned Behaviour. Of the 318 surveys distributed, there were 302 partiCipants who completed a usable survey from the sample of post-secondary intramural sport participants. There was a fairly even split of males and females; the average age of the students was twenty-one; 90% were undergraduate students; for approximately 25% of the students, volleyball was the only intramural sport they participated in at Brock and most were part of the volleyball competitive B division. Based on the post-secondary students responses, there are indications of intent to continue participation in sport and physical activity. The participation of the students is predominantly influenced by subjective norms, high sport commitment, and high sport enjoyment. This implies students expect, intend and want to 1 participate in intramurals in the future, they are very dedicated to playing on an intramural team and would be willing to do a lot to keep playing and students want to participate when they perceive their pursuits as enjoyable and fun, and it makes them happy. These are key areas that should be targeted and pursued by sport practitioners.
Resumo:
In 1833 William Clarke, the collector of customs at Niagara, completed and signed four forms for the movement of goods between Niagara and York, and Niagara and Brantford. The forms were issued to the firm of Lewis & Gray, James Armstrong, J.A. Wilks, and William Blackely. The goods being transported included scythes, corn brooms, hide whips, sacks, snuff, shovels, spades and two apple trees.
Resumo:
Item one is a minute book for Grantham Township, Ontario. It records the proceedings of meetings from 1818-1854 and the names of parish and town officers from 1818 to 1842. Names include: Chisholm, Ball, Steele, TenBroeck, Shipman, Laraway, McKerney, Adams, Pawling, Merritt, Rolls, Robertson, Lampman, Phelps, Darling. Also notes the laws agreed upon for the period - mainly dealing with livestock. Item two is a report and evidence of boundary line disputes in the Township of Grantham. Includes affidavits from witnesses to the boundary dispute and a report to the Honourable the Commissioner of Crown Lands Quebec. The affadavits were recorded in 1844, and transcribed into the folio in 1852. Lewis A. Ball was the commissioner before whom the affadavits were sworn and duly recorded. Includes field notes by Frederic F. Passmore, Provincial land surveyor. The boundary lines in dispute were 1. between the 2nd and 3rd Concessions, from Lot no. 1 to Lot no. 5, 2. between the 4th and 5th concessions, from lot no. 4 to lot no. 5 and 3. between lots 14 in the 9th and 10th concession of the Township of Grantham.
Resumo:
Lewis Tyrell married Jane Gains on August 31, 1849 in Culpeper Court House, Virginia. Jane Gains was a spinster. Lewis Tyrell died September 25, 1908 at his late residence, Vine St. and Welland Ave., St. Catharines, Ont. at the age of 81 years, 5 months. Jane Tyrell died March 1, 1886, age 64 years. Their son? William C. Tyrell died January 15, 1898, by accident in Albany, NY, age 33 years, 3 months. John William Taylor married Susan Jones were married in St. Catharines, Ont. on August 10, 1851 by William Wilkinson, a Baptist minister. On August 9, 1894 Charles Henry Bell (1871-1916), son of Stephen (1835?-1876) and Susan Bell, married Mary E. Tyrell (b. 1869?) daughter of Lewis and Alice Tyrell, in St. Catharines Ontario. By 1895 the Bell’s were living in Erie, Pennsylvania where children Delbert Otto (b. 1895) and Edna Beatrice (b. 1897) were born. By 1897 the family was back in St. Catharines where children Lewis Tyrell (b. 1899), Gertrude Cora (b. 1901), Bessie Jane (b. 1902), Charles Henry (b. 1906), Richard Nelson (b. 1911) and William Willoughby (b. 1912) were born. Charles Henry Bell operated a coal and ice business on Geneva Street. In the 1901 Census for St. Catharines, the Bell family includes the lodger Charles Henry Hall. Charles Henry Hall was born ca. 1824 in Maryland, he died in St. Catharines on November 11, 1916 at the age of 92. On October 24, 1889 Charles Hall married Susan Bell (1829-1898). The 1911 Census of Canada records Charles Henry Hall residing in the same household as Charles Henry and Mary Bell. The relationship to the householder is step-father. It is likely that after Stephen Bell’s death in 1876, his widow, Susan Bell married Hall. In 1939, Richard Nelson Bell, son of Charles Henry and Mary Tyrell Bell, married Iris Sloman. Iris (b. 22 May 1912 in Biddulph Township, Middlesex, Ontario) was the daughter of Albert (son of Joseph b. 1870 and Elizabeth Sloman, b. 1872) and Josie (Josephine Ellen) Butler Sloman of London, Ont. Josie (b. 1891) was the daughter of Everett Richard and Elizabeth McCarthy (or McCarty) Butler, of Lucan Village, Middlesex North. According to the 1911 Census of Canada, Albert, a Methodist, was a porter on the railroad. His wife, Josephine, was a Roman Catholic. Residing with Albert and Josie were Sanford and Sadie Butler and Sidney Sloman, likely siblings of Albert and Josephine. The Butler family is descended from Peter Butler, a former slave, who had settled in the Wilberforce Colony in the 1830s. Rick Bell b. 1949 in Niagara Falls, Ont. is the son of Richard Nelson Bell. In 1979, after working seven years as an orderly at the St. Catharines General Hospital while also attending night school at Niagara College, Rick Bell was hired by the Thorold Fire Dept. He became the first Black professional firefighter in Niagara. He is a founding member of the St. Catharines Junior Symphony; attended the Banff School of Fine Arts in 1966 and also performed with the Lincoln & Welland Regimental Band and several other popular local groups. Upon the discovery of this rich archive in his mothers’ attic he became passionate about sharing his Black ancestry and the contributions of fugitive slaves to the heritage Niagara with local school children. He currently resides in London, Ont.
Resumo:
Survey map of the Second Welland Canal created by the Welland Canal Company showing the Grantham Township between the Town of St. Catharines and Merritton. Identified structures associated with the Canal include Locks 9 and 10, waste weirs, the towing path, a 2nd towing path, and the Canal waterway itself. The surveyors' measurements and notes can be seen in red and black ink and pencil. Local area landmarks are also identified and include roads (ex. Road to Centreville), hydraulic race, and the Centreville Mill. Properties and property owners of note are: Concession 8 Lots 12 and 12, Lewis Traver, Richard Ash, John Bradley, Owen Clifford, Orson Phelps, C. Bradley, the W. C. Loan Company, and T. Towers Mill Lot.
Resumo:
The Marriages page from the Bell Family Bible listing the marriage of Lewis Tyrell to Jane Gains on Aug. 31, 1849 at Culpepper Court House, Virginia. This Bible was in the possession of the Richard Bell Family of St. Catharines, Ontario. Ancestors of the Bell family include former American slaves who settled in Canada.
Resumo:
The Deaths page from the Bell Family Bible listing the deaths of Jane Tyrrell in 1886, William C. Tyrrell in 1898, and Lewis Tyrrell in 1908. This Bible was in the possession of the Rick Bell family of St. Catharines, Ontario. Relatives of the Bell family were former Black slaves from the United States who settled in Canada.The handwritten entry appears to read as follows: "Jane Tyrrell, died March 1st 1886 age 64 yrs. William C. Tyrrell died January 15th 1898 by accident in Albany N.Y. age 33 yrs 3 months Lewis Tyrrell died September 25th 1908 at his late residence Vine and Welland Ave. St. Catharines age 81 yrs 5 months." There are various spellings of the Tyrrell name within the Bell family archive. Other forms of the name include Tyrell, Tyrrill, and Terrell.
Resumo:
A page from the Bell Family Bible entitled "Miscellaneous" recording the dates and places of birth of the children of Charles and Mary Bell. The birth dates for the eight children listed range from 1895 to 1918. There is also a single entry under the heading "Age of Children of Delbert Bell". This Bible was in the possession of the Rick Bell of St. Catharines. The Bell family is descended from former Black slaves from the United States who settled in Canada.The handwritten entries appear to be as follows: "Ages of the children of Charles and Mary Bell are Wilbert Otto Bell born November 7th 1895 Erie Pa. Edna Beatrice Bell born May 25th 1897 Erie Pa. Lewis Terrell Bell born April 8th 1899 St. Catharines Ont. Gertrude Bell born November 26th 1902 St. Catharines Ont. Charles Henry Bell born June 6th 1906 St. Catharines Ont. Richard Wilson Bell born March 19th 1911 William Willoughby Bell born May 2nd 1912 both in St. Catharines Ontario Age of Children of Delbert Bell March 12th 1918 Delbert Charlie Bell"