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首頁> 外文學位 >Ribbonators in magnetic resonance imaging of the hand and wrist, a dynamical approach to NMR of macromolecule bound nuclei of half-integer spin greater than 1/2, and cross-polarization NMR in polymers at liquid helium temperatures.
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Ribbonators in magnetic resonance imaging of the hand and wrist, a dynamical approach to NMR of macromolecule bound nuclei of half-integer spin greater than 1/2, and cross-polarization NMR in polymers at liquid helium temperatures.

機譯：手腕和腕部磁共振成像中的帶式成像儀，一種動態(tài)方法，用于對大于整數(shù)的半整數(shù)自旋的大分子結(jié)合核進行NMR核磁共振，以及在液氦溫度下聚合物中的交叉極化NMR。

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he optimization of single-turn solenoids for use in magnetic resonance imaging of the hand and wrist was studied. A "ribbonator" is a device that is electrically similar to a loop-gap resonator but is of rectangular geometry. These resonators exhibited radio-frequency magnetic field homogeneity superior to commonly used surface coils, and eliminated artifacts caused by inhomogeneous transmission and detection field distributions. These devices allowed reorientation of the hand to radial and ulnar deviations, with the hand in place within the resonator. Images are presented that show excellent anatomical detail and no significant artifacts from field inhomogeneity.;Decreasing the temperature of a sample increases its thermal equilibrium nuclear magnetization, and, if the temperature of a sample is decreased from room temperature to near liquid helium temperatures, a net increase in NMR signal of nearly 70 fold is expected. However, decreasing the sample temperature also increases longitudinal relaxation rates in the solid and, because of changes in the spin dynamics of the system at low temperatures, can possibly introduce spectral artifacts. The combination of decreasing sample temperature along with the ;The effect on linewidth of manipulating the rotational correlation time of a macromolecule to which a quadrupolar nucleus is bound was explored. A dynamical regime is sought in which the molecule rotates quickly enough such that second order quadrupolar interaction contributions are averaged, but still slowly enough that transverse relaxation times are long and first order quadrupolar interactions are not averaged away. Bovine serum albumen and ethylenediaminetetraacetic acid complexes with aluminum were studied as well as aluminum in various clays. No dynamical regime was found that yields aluminum resonance line-widths smaller than
機譯：研究了用于手和腕部磁共振成像的單匝螺線管的優(yōu)化。 “帶狀諧振器”是一種電氣上類似于環(huán)形間隙諧振器但具有矩形幾何形狀的設備。這些諧振器表現(xiàn)出優(yōu)于常用表面線圈的射頻磁場均勻性，并消除了由不均勻的傳輸和檢測場分布引起的偽影。這些設備允許將手重新定位到徑向和尺骨偏斜，并且將手放在共振器內(nèi)。所顯示的圖像顯示出出色的解剖學細節(jié)，并且沒有場不均勻性造成的明顯偽影。;降低樣品的溫度會增加其熱平衡核磁化強度;并且，如果樣品的溫度從室溫降低到接近液氦溫度，則預計NMR信號將凈增加近70倍。但是，降低樣品溫度也會增加固體中的縱向弛豫速率，并且由于低溫下系統(tǒng)的自旋動力學變化，可能會引入光譜偽影。探索了降低樣品溫度以及結(jié)合使用的影響；研究了操縱四極核所結(jié)合的大分子的旋轉(zhuǎn)相關時間對線寬的影響。尋求一種動態(tài)機制，其中分子旋轉(zhuǎn)得足夠快，以使得對二階四極相互作用的貢獻被平均，但是仍然足夠慢，使得橫向弛豫時間長并且一階四極相互作用沒有被抵消。研究了牛血清蛋白和乙二胺四乙酸與鋁的絡合物以及各種粘土中的鋁。沒有發(fā)現(xiàn)產(chǎn)生鋁共振線寬小于

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  • 作者

    Marshall, Eric Alan.;

  • 作者單位

    University of Rochester.;

  • 授予單位 University of Rochester.;
  • 學科 Biophysics.;Biophysics.
  • 學位 Ph.D.
  • 年度 1990
  • 頁碼 242 p.
  • 總頁數(shù) 242
  • 原文格式 PDF
  • 正文語種 eng
  • 中圖分類
  • 關鍵詞

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