21 resultados para Double wishbone suspension

em Brock University, Canada


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Therllloelynalllics of lllodel 11lel1ll)rane systeills containing 1110nollnsaturatecl I)lloSI)holil) ids is strongly infllienced l)y the I)osition of the C==C dOlll)le })ond in tIle acyl chain. The telllI)eratllres of both chain-nlelting (TM) and La -+ HI! (TH) I)hase traIlsitions are lowered by IIp to 20°C when C==C is Inoved froln positions 6 or 11 to I)osition 9 in an 18-carl)on chain. This work is an attellll)t to ellicidate the uIlderlying Illoleclilar Illechanisllls reSI)Onsi])le for tllese draillatic tllerillodynaillic changes. Mixtllres of di-18: 1 l)hoSI)hatidylethanolanline with C==C at l)ositioIlS 6, 9, 11 were llsed, witll a sI1lall aI1lOlint of I)erdellterated tetradecanol, known to })e a gooel rel)Orter of the cllain Illoleclilar order. SI)ectral second 11I0I1lents were llsed to Illonitor tIle La -+ HII I)hase transition, which was fOllnd to ])e ])road (2-6°C), with a slight llysteresis on heatiIlg/cooling. The orientational order I)rofiles were nleasllred 1lSiIlg 2H Illiclear Illagnetic resonance and changes in these order I)rofiles between La aIld HII I)hases silow l)oth a local increase in order in the vicinity of the C==C bonds and an o\Terall decrease ill the average orientational order of the chain as a whole. These Sll])tle changes recluire })oth high-fidelity SI)ectrosCol)y and a careflll data analysis that takes into aCCOllnt the effects due to l)artiall1lagnetically-indllced orientational ordering of the l)ilayers. In tIle COIltext of SOllle recently rel)Orted cross-relaxation 11leaSlirenlents in Silllilar l)llOSI)llolil)iels, 0111' reslilts sllggest that large-anll)litllde conforlllational changes in the interior of tIle I110del 111eI11])ranes I)lay a 1110re significant role than I)reviollsly thOllght.

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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.

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The steeply dipping, isoclinally folded early Precambrian (Archean) Berry Creek Metavolcanic Complex comprises primary to resedimented pyroclastic, epiclastic and autoclastic deposits. Tephra erupted from central volcanic edifices was dumped by mass flow mechanisms into peripheral volcanosedimentary depressions. Sedimentation has been essentially contemporaneous with eruption and transport of tephra. The monolithic to heterolithic tuffaceous horizons are interpreted as subaerial to subaqueous pumice and ash flows, secondary debris flows, lahars, slump deposits and turbidites. Monolithic debris flows, derived from crumble breccia and dcme talus, formed during downslope collapse and subsequent gravity flowage. Heterolithic tuff, lahars and lava flow morphologies suggest at least temporary emergence of the edifice. Local collapse may have accompanied pyroclastic volcanism. The tephra, produced by hydromagmatic to magmatic eruptions, were rapidly transported, by primary and secondary mechanisms, to a shallow littoral to deep water subaqueous fan developed upon the subjacent mafic metavolcanic platform. Deposition resulted from traction, traction carpet, and suspension sedimentation from laminar to turbulent flows. Facies mapping revealed proximal (channel to overbank) to distal facies epiclastics (greywackes, argillite) intercalated with proximal vent to medial fan facies crystal rich ash flows, debris flows, bedded tuff and shallow water to deep water lava flows. Framework and matrix support debris flows exhibit a variety of subaqueous sedimentary structures, e.g., coarse tail grading, double grading, inverse to normal grading, graded stratified pebbly horizons, erosional channels. Pelitic to psammitic AE turbidites also contain primary stru~tures, e.g., flames, load casts, dewatering pipes. Despite low to intermediate pressure greenschist to amphibolite grade metamorphism and variably penetrative deformation, relicts of pumice fragments and shards were recognized as recrystallized quartzofeldspathic pseudomorphs. The mafic to felsic metavolcanics and metasediments contain blasts of hornblende, actinolite, garnet, pistacitic epidote, staurolite, albitic plagioclase, and rarely andalusite and cordierite. The mafic metavolcanics (Adams River Bay, Black River, Kenu Lake, Lobstick Bay, Snake Bay) display _holeiitic trends with komatiitic affinities. Chemical variations are consistent with high level fractionation of olivine, plagioclase, amphibole, and later magnetite from a parental komatiite. The intermediate to felsic (64-74% Si02) metavolcanics generally exhibit calc-alkaline trends. The compositional discontinuity, defined by major and trace element diversity, can be explained by a mechanism involving two different magma sources. Application of fractionation series models are inconsistent with the observed data. The tholeiitic basalts and basaltic andesites are probably derived by low pressure fractionation of a depleted (high degree of partial melting) mantle source. The depleted (low Y, Zr) calc-alkaline metavolcanics may be produced by partial melting of a geochemically evolved source, e.g., tonalitetrondhjemite, garnet amphibolite or hydrous basalt.

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In 1846, the governments of Upper Canada and the State of New York initiated the creation of two companies that would be authorized to build a bridge over the Niagara River. The bridge was to be owned by both companies, respectively known as the Niagara Falls Suspension Bridge Company (Canadian) and the International Bridge Company (American). A suspension bridge was completed in 1848. This bridge was later replaced by a second suspension bridge that accommodated railways, built in 1853-54. However, the increasing weight of trains made it necessary for the bridge to be redesigned, and a third bridge was completed in 1886. Eventually, this bridge was replaced by a steel arch bridge, which was completed in 1897.

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Final Report of John A. Roebling, Civil Engineer, to the Presidents and Directors of the Niagara Falls International Bridge Companies.

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Final report of John A. Roebling, Civil Engineer, to the presidents and directors of the Niagara Falls Suspension and Niagara Falls International Bridge Companies, on the condition of the Niagara Railway Suspension Bridge.

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Contains "Acts of Parliament of Province of Canada and Acts of Parliament of Dominion of Canada."

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The Niagara Suspension Bridge Bank operated in Queenston in 1840. The bank issued notes in denominations of ten dollars, five dollars and one dollar, and featured a drawing of the Queenston-Lewiston Bridge, ten years prior to its construction. The notes are signed by the bank’s Cashier, Gilbert McMicken, and President, Joseph Hamilton. The bank failed a year after its establishment.

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This thesis describes the chemoenzymatic synthesis of three morphine alkaloids. The total synthesis of dihydrocodeine and hydrocodone was accomplished starting from bromobenzene in 16 and 17 steps, respectively. The key steps included a microbial oxidation of bromobenzene by E. coli JM109 (pDTG601A), a Kazmaier-Claisen rearrangement of glycinate ester to generate C-9 and C-14 stereo centers, a Johnson-Claisen rearrangement to set the C-13 quaternary center, and a C-10/C-11 ring closure via a Friedel-Crafts reaction. In addition, the total synthesis of ent-hydromorphone starting from β-bromoethylbenzene in 12 steps is also described. The key reactions included the enzymatic dihydroxylation of β-bromoethylbenzene to the corresponding cis-cyclohexadienediol, a Mitsunobu reaction, and an oxidative dearomatization followed by an intramolecular [4+2] cycloaddition.

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The summary of the article reads "A new double rail conveyor restrainer for handling cattle at the slaughter plant is described. It has improved safety and ergonomics compared to the V restrainer conveyor it replaces. Cattle ride astride a moving conveyor. This design could also be adapted for veterinary work."