White organic light-emitting device with\ both phosphorescent and fluorescent emissive layers

This paper reports the fabrication of novel white organic light-emitting device（WOLED） by using a high efficiency blue fluorescent dye N-（4-（（E）-2-（6-（（E）-4-（diphenylamino）styryl）naphthalen-2-yl）vinyl）phenyl）oN- phenylbenzenamine （N-BDAVBi） and a red phosphoresecent dye bis （1-（phenyl） isoquinoline） iridium （III） acetylanetonate （Ir（piq）2（acac））. The configuration of the device was ITO/PVK：TPD/CBP： N-BDAVBi /CBP/ BALq： Ir（piq）2（acac）/BCP/Alq3/LiF：AL. By adjusting the proportion of the dopants （N-BDAVBi, Ir（piq）2（acac）） in the light-emitting layer, white light with Commission Internationale de l＇Eclairage （CIE） coordinates of （0.35, 0.35） and a maximum luminance of 25350cd/m2 were obtained external quantum and current efficiency of 6.78% and between the two light-emitting layers and using BCP at an applied voltage of 22V. The WOLED exhibits maximum 12cd/A respectively. By placing an undoped spacer CBP layer as hole blocking layer, the colour stabilization slightly changed when the driving voltage increased from 6 to 22 V.     

利用三维荧光结合平行因子算法研究金属离子对溶解性有机物的猝灭和校正

溶解性有机物的荧光组份由于受到金属离子的影响其荧光强度受到变化,从而为溶解性有机物的定量分析带来挑战。利用三维荧光结合平行因子分析方法研究了Cu(Ⅱ), Fe(Ⅲ), Ni(Ⅱ), Sr(Ⅱ), Hg(Ⅱ), K(Ⅰ), Mg(Ⅱ) 和Mn(Ⅱ)八个金属离子对典型溶解性有机物荧光组分的荧光猝灭作用,五个水样来源各不相同。实验表明水样被平行因子成功分解为三个荧光组分(色氨酸、腐殖酸、富里酸),这三个荧光组份的荧光得分随着Fe(Ⅲ), Cu(Ⅱ), Hg (Ⅱ)和 Ni(Ⅱ)浓度的增加呈线性或指数下降。在这四种离子中,Fe(Ⅲ)和Cu(Ⅱ)对腐殖酸和富里酸的荧光猝灭作用明显大于Hg (Ⅱ)和 Ni(Ⅱ)。Sr(Ⅱ), K(Ⅰ), Mg(Ⅱ)和Mn(Ⅱ)基本没有影响。其中Fe(Ⅲ)对于三个荧光组分的荧光猝灭都有较好的分析。由于只考虑Fe(Ⅲ) 和Cu(Ⅱ)的影响,对于含有金属离子的饮用水的荧光强度的校正曲线也被建立。不同来源的饮用水中荧光组份的荧光得分的衰减规律也是不一样的,因此水样的来源也是测量时需要考虑的因素。实验证实了金属离子对溶解性有机物的荧光猝灭作用以及其他因素比如Fe(Ⅲ) 和Cu(Ⅱ)和溶解性有机物本身的多样性都是我们荧光测量典型荧光组份时需要考虑的。表明三维荧光结合平行因子分析方法是一个有效的准确测量溶解性有机物荧光组份的工具。     

卟啉配合物-巯基棉体系分光光度法测定中药中铅、镉、铜

研究了卟啉与铅、镉、铜的反应及配合物的电子吸收光谱。结合巯基棉分离富集方法 ,将此金属卟啉配合物体系成功地应用于中药中微量铅、镉、铜的测定。方法简便 ,测定体系抗干扰的效果好 ,灵敏度高。实际样品测定的RSD在 3 3%～ 9 6 %之间。样品加标回收率在 90 %～ 1 0 3%之间。     

The zonal architecture of human articular cartilage described by T2 relaxation time in the presence of Gd-DTPA2-

The depth-wise variation of T(2) relaxation time is known to reflect the collagen network architecture in cartilage, while the delayed Gadolinium Enhanced MRI of Cartilage (dGEMRIC) technique is sensitive to tissue proteoglycan (PG) concentration. As the cartilage PG content varies along the tissue depth, the depth-dependent accumulation of the contrast agent may affect the inherent T(2) of cartilage in a nonconstant manner. Therefore, T(2) and dGEMRIC are typically measured in separate MRI sessions. In the present in vitro MRI study at 9.4 T, depth-wise T(2) profiles and collagenous zone thicknesses as determined from T(2) maps in the absence and presence of Gd-DTPA(2-) (T(2) and T(2Gd), respectively) were compared in samples of intact human articular cartilage (n=65). These T(2) measures were further correlated with birefringence (BF) of polarized light microscopy (PLM) to quantify the ability of MRI to predict the properties of the collagen fibril network. The reproducibility of the T(2) measurement in the current setup was also studied. Typical tri-laminar collagen network architecture was observed both with and without Gd-DTPA(2-). The inverse of BF (1/BF) correlated significantly with both T(2) and T(2Gd) (r=0.91, slope=0.56 and r=0.90, slope=0.63), respectively. The statistically significant linear correlations between zone thicknesses as determined from T(2) and T(2Gd) were r=0.55 (slope=0.49), r=0.74 (slope=0.71) and r=0.95 (slope=0.94) for superficial, middle and deep tissue zones, respectively. Reproducibility of the T(2) measurement was worst for superficial cartilage. Consistent with PLM, T(2) and T(2Gd) measurements reveal highly similar depth-dependent information on collagen network in intact human cartilage. Thus, dGEMRIC and T(2) measurements in one MRI session are feasible for intact articular cartilage in vitro.     

Principal eigenvector field segmentation for reproducible diffusion tensor tractography of white matter structures

The study was aimed to test the feasibility of utilizing an algorithmically determinable stable fiber mass (SFM) map obtained by an unsupervised principal eigenvector field segmentation (PEVFS) for automatic delineation of 18 white matter (WM) tracts: (1) corpus callosum (CC), (2) tapetum (TP), (3) inferior longitudinal fasciculus (ILF), (4) uncinate fasciculus (UNC), (5) inferior fronto-occipital fasciculus (IFO), (6) optic pathways (OP), (7) superior longitudinal fasciculus (SLF), (8) arcuate fasciculus (AF), (9) fornix (FX), (10) cingulum (CG), (11) anterior thalamic radiation (ATR), (12) superior thalamic radiation (STR), (13) posterior thalamic radiation (PTR), (14) corticospinal/corticopontine tract (CST/CPT), (15) medial lemniscus (ML), (16) superior cerebellar peduncle (SCP), (17) middle cerebellar peduncle (MCP) and (18) inferior cerebellar peduncle (ICP). Diffusion tensor imaging (DTI)-derived fractional anisotropy (FA) and the principal eigenvector field have been used to create the SFM consisting of a collection of linear voxel structures which are grouped together by color-coding them into seven natural classes to provide PEVFS signature segments which greatly facilitate the selection of regions of interest (ROIs) for fiber tractography using just a single mouse click, as compared with a manual drawing of ROIs in the classical approach. All the 18 fiber bundles have been successfully reconstructed, in all the subjects, using the single ROIs provided by the SFM approach, with their reproducibility characterized by the fact that the ROI selection is user independent. The essentially automatic PEVFS method is robust, efficient and compares favorably with the classical ROI methods for diffusion tensor tractography (DTT).     

The effects of dissolved oxygen upon amide proton relaxation and chemical shift in a perdeuterated protein

The effects of dissolved molecular oxygen upon amide proton ((1)H(N)) longitudinal and transverse relaxation rates and chemical shifts were studied for a small protein domain, the second type 2 module of fibronectin ((2)F2)-isotopically enriched to 99% (2)H, 98% (15)N. Longitudinal relaxation rate enhancements, R(O(2))((1)H(N)), of individual backbone (1)H(N) nuclei varied up to 14 fold between a degassed and oxygenated (1 bar) solution, indicating that the oxygen distribution within the protein is inhomogeneous. On average, smaller relaxation rate enhancements were observed for (1)H(N) nuclei associated with the core of the protein compared to (1)H(N) nuclei closer to the surface, suggesting restricted oxygen accessibility to some regions. In agreement with an O(2)-(1)H(N) hyperfine interaction in the extreme narrowing limit, the (1)H(N) transverse relaxation rates showed no significant change, up to an oxygen pressure of 9.5 bar (the maximum pressure used in this study). For most (1)H(N) resonances, small deltadelta(O(2))((1)H(N)) hyperfine chemical shifts could be detected between oxygen pressures of 1 bar and 9.5 bar.     

Improved thermoelectric performance in p-type Bi_(0.48)Sb_(1.52)Te_3 bulk material by adding MnSb_2Se_4

Bismuth telluride(Bi_2Te_3) based alloys, such as p-type Bi_(0.5)Sb_(1.5)Te_3, have been leading candidates for near room temperature thermoelectric applications. In this study, Bi_(0.48)Sb_(1.52)Te_3 bulk materials with MnSb_2Se_4 were prepared using high-energy ball milling and spark plasma sintering(SPS) process. The addition of MnSb_2Se_4 to Bi_(0.48)Sb_(1.52)Te_3 increased the hole concentration while slightly decreasing the Seebeck coefficient, thus optimising the electrical transport properties of the bulk material. In addition, the second phases of MnSb_2Se_4 and Bi_(0.48)Sb_(1.52)Te_3 were observed in the Bi_(0.48)Sb_(1.52)Te_3 matrix. The nanoparticles in the semi-coherent second phase of MnSb_2Se_4 behaved as scattering centres for phonons,yielding a reduction in the lattice thermal conductivity. Substantial enhancement of the figure of merit, ZT, has been achieved for Bi_(0.48)Sb_(1.52)Te_3 by adding an Mn_(0.8)Cu_(0.2)Sb_2Se_4(2mol%) sample, for a wide range of temperatures, with a peak value of 1.43 at 375 K, corresponding to ~40% improvement over its Bi_(0.48)Sb_(1.52)Te_3 counterpart. Such enhancement of the thermoelectric(TE) performance of p-type Bi_2Te_3 based materials is believed to be advantageous for practical applications.     

纳米相氟氧化物玻璃陶瓷中Er3+Yb3+离子对的量子剪裁发光造成的强的光谱调制

研究了纳米相氟氧化物玻璃陶瓷中Er3+Yb3+离子对的量子剪裁发光造成的强的光谱调制现象。测量了Er3+Yb3+双掺纳米相氟氧化物玻璃陶瓷的X射线衍射谱、表面形貌、激发光谱、吸收光谱、和发光光谱;而且也与Tb3+Yb3+双掺纳米相氟氧化物玻璃陶瓷的相对应的光谱参数进行了比较。发现378 nm光激发样品(A) Er(1%)Yb(8.0%)∶FOV和样品(B) Er(0.5%)Yb(3.0%)∶FOV所导致的652.0 nm红色发光强度为522 nm光激发时的680.85倍和303.80倍;我们还发现378 nm光激发所导致的样品(A) Er(1%)Yb(8.0%)∶FOV和样品(B) Er(0.5%)Yb(3.0%)∶FOV的 652.0 nm红色发光强度为样品(C) Er(0.5%)∶FOV 的491.05和184.12倍。我们还发现在378 nm光激发时的样品(A) Er(1%)Yb(8.0%)∶FOV和样品(B) Er(0.5%)Yb(3.0%)∶FOV的{978.0和1 012.0 nm}红外发光强度依次分别为样品(C) Er(0.5%)∶FOV 的{58.00和293.62}倍和{25.11和 67.50}倍。更进一步,对于652.0 nm波长发光的激发谱,发现(A) Er(1%)Yb(8.0%)∶FOV和(B) Er(0.5%)Yb(3.0%)∶FOV的378.5 nm激发谱峰强度是(C) Er(0.5%)∶FOV的大约606.02和199.83倍。同时,也发现样品(A) Er(1%)Yb(8.0%)∶FOV和样品(B) Er(0.5%)Yb(3.0%)∶FOV的一级量子剪裁红外1 012或978 nm发光强度为样品(D) Tb(0.7%)Yb(5.0%)∶FOV的二级量子剪裁红外976 nm发光强度的101.38和29.19倍。发现的该量子剪裁是目前所报道的最强的量子剪裁。因此,相信所发现的氟氧化物纳米玻璃陶瓷中Er3+Yb3+离子对的一级量子剪裁发光是强的可以作为量子剪裁层应用到提高晶硅太阳能电池的发电效率。研究结果也能加速对目前国际热点的下一代环保的光谱调制太阳能电池的探索。     

紫外差光谱测定Gd(Ⅲ), Yb(Ⅲ)与HBED配合物的条件稳定常数

在0.01 mol·L-1 N-2-羟乙基哌嗪-N'-2-乙磺酸(Hepes), pH 7.4, 室温条件下, 应用紫外差光谱滴定观察了Gd(Ⅲ), Yb(Ⅲ)与N, N'-二(2-羟苄基)乙二胺-N, N'-二乙酸(HBED)的结合. 结果表明 Gd(Ⅲ), Yb(Ⅲ)与HBED均形成1∶1的配合物, 其紫外差光谱均于237和291 nm处出现吸收峰, 在237 nm处配合物Gd-HBED与Yb-HBED的摩尔吸光系数分别为 ΔεGd=(22.52±0.20)×103 cm-1·mol-1·L, ΔεYb=(27.15±0.11)×103 cm-1·mol-1·L; 配合物Gd-HBED与Yb-HBED的条件稳定常数分别为 lgKGd-HBED=13.56±0.28, lgKYb-HBED=16.06±0.03, 符合线性自由能关系.     

吸光度比值-导数光谱法同时测定铜(Ⅱ)和铬(Ⅲ)的研究

提出了运用吸光度比值-导数光谱法同时测定Cr(Ⅲ)与Cu(Ⅱ)含量的新方法。在pH 5.7的HAc-NaAc的缓冲溶液中,Cr3+,Cu2+与铬天青S(CAS)和溴化十六烷基三甲胺(CTMAB)可分别形成蓝色三元络合物。其摩尔吸光系数分别为2.52×105 L·mol-1·cm-1和1.01×105 L·mol-1·cm-1。Cu2+和Cr3+的浓度分别在0.08～1.2 μg·mL-1和0.05～0.52 μg·mL-1范围内符合比尔定律,其检测限分别为0.014和0.013 μg·mL-1。此方法应用于环境水中Cr(Ⅲ),Cu(Ⅱ)的同时测定,取得了满意的结果。     

Zn1-xMgxO薄膜p型导电和光学性能

采用超声喷雾热分解(Ultrasonic Spray Pyrolysis,USP)方法,以醋酸锌、醋酸镁、醋酸铵、氯化铝的混合水溶液为前驱溶液,在单晶Si(100)衬底上制备了ZnO,Zn_0.81Mg_0.19O,N-Al共掺杂ZnO和N-Al共掺杂Zn_0.81Mg_0.19O薄膜。以X射线衍射(XRD)、场发射-扫描电镜(FE-SEM)、霍尔效应(Hall-effect)、光致发光(Photoluminescence,PL)谱等手段研究了薄膜的晶体结构、表面形貌、电学性能、光学性能和带隙变化。电学测试结果表明,未掺杂ZnO及Zn_0.81Mg_0.19O薄膜为n型导电;而N-Al共掺杂ZnO和N-Al共掺杂Zn_0.81Mg_0.19O薄膜呈p型导电。Zn_0.81Mg_0.19O和N-Al共掺杂Zn_0.81Mg_0.19O(p型)薄膜在维持ZnO纤锌矿结构的前提下,光学带隙随Mg掺杂量增加而增大。初步结果显示,优化工艺参数下通过Mg掺杂制备光学带隙可调的p型Zn_0.81Mg_0.19O薄膜,对于试制Zn_1-xMg_xO基同质p-n结、短波长(紫外、深紫外)器件等方面有重要意义。     

界面对Fe65Co35薄膜微结构和软磁性的影响

用不同的材料（Co₉₃Fe₇和Fe）作衬底层,利用磁控溅射法成功制备了Fe₆₅Co₃₅（主层）/衬底层结构的双层薄膜．通过X射线衍射和磁性测量发现,在不同的衬底上沉积的Fe₆₅Co₃₅薄膜的织构不同,并且（200）取向的Fe₆₅Co₃₅薄膜的面内各向异性和软磁性优于（110）取向的Fe₆₅Co_{35关键词： 65}Co₃₅薄膜')" href="#">Fe₆₅Co₃₅薄膜 衬底层 界面各向异性 软磁性     

The v(1)+v(3) Bands of the (16)O(17)O(16)O and (16)O(16)O(17)O Isotopomers of Ozone

Using 0.002 cm(-1) resolution Fourier transform absorption spectra of an (17)O enriched ozone sample, an extensive analysis of the v(1)+v(3) bands of the (16)O(17)O(16)O and (16)O(16)O(17)O isotopomers of ozone has been performed for the first time. The experimental rotational levels of the (101) vibrational states were satisfactorily reproduced using a Hamiltonian matrix that takes into account the observed rovibrational resonances. More precisely, for (16)O(17)O(16)O, as for the other C(2v)-type ozone isotopomers, it was necessary to account for the Coriolis type resonances linking the (101) rotational levels with the levels of the (200) and (002) vibrational states and the Darling-Dennison interaction coupling the levels of (200) with those of (002). For the C(s)-type isotopomer, namely (16)O(16)O(17)O, as for (16)O(16)O(18)O and (16)O(18)O(18)O, it proved necessary to also account for an additional DeltaK(a)&equals+/-2 resonance involving the rotational levels from (101) and (002) (J.-M. Flaud and R. Bacis, Spectrochimica Acta Part A 54, 3-16 (1998)). Using a Hamiltonian matrix which takes these resonances explicitly into account, precise vibrational energies and rotational and coupling constants were deduced, leading to the following band centers: v(0)(v(1)+v(3))=2078.3496 cm(-1) for (16)O(17)O(16)O and v(0)(v(1)+v(3))=2098.8631 cm(-1) for (16)O(16)O(17)O. Copyright 2001 Academic Press.     

PEG-Na2SO4-PAR体系中Pd(Ⅱ)、U(Ⅵ)、Mo(Ⅵ)的萃取分离

本文研究了在聚乙二醇－２０００（ＰＥＧ）－硫酸钠（Ｎａ２ＳＯ４）－４－（２－吡啶偶氮）－间苯二酚（ＰＡＲ）体系中,Ｐｄ（Ⅱ）、Ｕ（Ⅵ）、Ｌａ（Ⅲ）、Ｍｏ（Ⅵ）的萃取行为。实验结果表明,在ｐＨ４．５￣７．５溶液中,Ｐｄ（Ⅱ）、Ｕ（Ⅵ）、可被ＰＥＧ相几乎完全萃取,Ｌａ（Ⅲ）部分被萃取,而Ｍｏ（Ⅵ）则不被蔺取,从而实现了Ｍｏ（Ⅵ）与Ｐｄ（Ⅱ）、Ｕ（Ⅵ）混合离子间的定量分离,并初步探讨了ＰＥＧ相的萃取机理     

利用光学-光学双共振研究谱线的碰撞增宽

利用光学-光学双共振光谱技术研究了NaK分子21Σ＋→６1Σ＋跃迁线的碰撞增宽。一台单模半导体激光器实现11Σ＋(v″,J″)→21Σ＋(v′,J′)的跃迁,另一单模半导体激光器激发21Σ＋(v′,J′)能级到６1Σ＋的振转能级,二激光束反向平行通过样品池。谱线总线宽与K原子密度成线性关系,由其斜率得到增宽速率系数k_br＝(1.4±0.7)×10-8 cm3·s-1。同时研究了21Σ＋(v＝8,J＝12)→21Σ＋(v＝8,J＝13,14)转动能级间的碰撞激发转移,测量谱线的相对强度,由速率方程得到碰撞转移速率分别为6.1×106和5.2×106 s-1。     

Fang–Howard wave function modelling of electron mobility in AlInGaN/AlN/InGaN/GaN double heterostructures

To study the electron transport properties in InGaN channel-based heterostructures,a revised Fang-Howard wave function is proposed by combining the effect of GaN back barrier.Various scattering mechanisms,such as dislocation impurity(DIS) scattering,polar optical phonon(POP) scattering,piezoelectric field(PE) scattering,interface roughness(IFR) scattering,deformation potential(DP) scattering,alloy disorder(ADO) scattering from InGaN channel layer,and temperature-dependent energy bandgaps are considered in the calculation model.A contrast of AlInGaN/AlN/InGaN/GaN double heterostructure(DH) to the theoretical AlInGaN/AlN/InGaN single heterostructure(SH) is made and analyzed with a full range of barrier alloy composition.The effect of channel alloy composition on InGaN channel-based DH with technologically important Al(In,Ga)N barrier is estimated and optimal indium mole fraction is 0.04 for higher mobility in DH with Al_(0.4)In_(0.07)Ga_(0.53)N barrier.Finally,the temperature-dependent two-dimensional electron gas(2 DEG) density and mobility in InGaN channel-based DH with Al_(0.83)In_(0.13)Ga_(0.0)4 N and Al_(0.4)In_(0.07)Ga_(0.53)N barrier are investigated.Our results are expected to conduce to the practical application of InGaN channel-based heterostructures.     

双水相体系中Cu(Ⅱ),La(Ⅲ),U(Ⅵ),Ce(Ⅳ)光谱行为及萃取分离

利用聚乙二醇2000(PEG)-(NH)2SO4-萃取剂(铜试剂)双水相体系,采用液-液萃取的方法,研究了PEG相、单纯水相中金属离子络合物及萃取剂的光谱行为,探讨了金属离子络合物在PEG相中存在形态及萃取机理。同时实验了在不同酸度,不同盐用量,不同萃取剂用量,以及在不同表面活性剂的影响下,铜、镧、铀、铈的萃取率,通过控制一定条件,实现了Cu(Ⅱ)与La(Ⅲ),Cu(Ⅱ)与Ce(Ⅳ)之间的定量萃取分离。     

图象复原的新后验方法

本文就某系统的动态图象的复原,阐述了复原的主要技术过程。提出了一种新的后验模型,即退化信息不是从退化图象本身中提取,而是从给定样本的一系列退化象中提取,从而可以用线性空不变系统的求解模型来处理非线性空变系统的图象复原问题。本文给出了用此方法所获得的处理结果。     

Equilibrium signal intensity mapping, an MRI method for fast mapping of longitudinal relaxation rates and for image enhancement

INTRODUCTION: Inhomogeneity of magnetic fields, both B(0) and B(1), has been a major challenge in magnetic resonance imaging (MRI). Field inhomogeneity leads to image artifacts and unreliability of signal intensity (SI) measurements. This work proposes and shows the feasibility of generating equilibrium signal intensity (SI(Eq)) maps that can be utilized either to speed up relaxation-rate measurement or to enhance image quality and relaxation-rate-based weighting in various applications. METHODS: A 1.5-T MRI scanner was used. In canines (n=4), myocardial infarction was induced, and 48 h after the administration of 0.05 mmol kg(-1) Gd(ABE-DTTA), a contrast agent with slow tissue kinetics, in vivo R(1) mapping was carried out using an inversion recovery (IR)-prepared, fast gradient-echo sequence with varying inversion times (TIs). To test the SI(Eq) mapping method without the confounding effects of motion and blood flow, we carried out ex vivo R(1) mapping after the administration of 0.2 mmol kg(-1) Gd(DTPA) using an IR-prepared, fast spin-echo sequence in another group of dogs (n=2). R(1,full) maps and SI(Eq) maps were generated from the data from both sequences by three-parameter nonlinear curve fitting of the SI versus TI dependence. R(1,full) maps served as the reference standard. Raw IR images were then divided by the SI(Eq) maps, yielding corrected SI maps (COSIMs). Additionally, R(1) values were calculated from each single-TI image separately, using the SI(Eq) value and a one-parameter curve-fitting procedure (R(1,single)). Voxelwise correlation analysis was carried out for the COSIMs and the R(1,single) maps, both versus the standard R(1,full) maps. Deviations of R(1,single) from R(1,full) were statistically evaluated. RESULTS: In vivo, COSIM versus R(1,full) showed significantly (P<.05) better correlation [correlation coefficient (CC)=0.95] than SI versus R(1,full) with a TI=700-800 ms, which is 200-300 ms longer than the tau(null) (500 ms) of viable myocardium. With such TIs, SI versus R(1,full) yielded CCs of 0.86-0.88. R(1,single) versus R(1,full) yielded a peak CC of 0.96 at TI=700-900 ms. Mean deviations of R(1,single) from R(1,full) were below 5% for TIs between 500 and 1000 ms. Ex vivo, where tau(null) was 300 ms, the advantage of correction with SI(Eq) was not in the improvement of linear correlation but more in the reduction of scatter. Peak CCs for SI versus R(1,full) and COSIM versus R(1,full) at TI=500 ms were 0.96 for both. The ex vivo CC for R(1,single) versus R(1,full) at TI=500 ms was 0.98. Mean deviations of R(1,single) from R(1,full) were below 5% for TIs between 400 and 700 ms. CONCLUSIONS: Once the corresponding SI(Eq) map is obtained from a control stack, R(1) can be obtained accurately, using only a single IR image and without the need for a stack of TI-varied images. This approach could be applied in various dynamic MRI studies where short measurement time, once the dynamics has started, is of essence. When using this method with IR-prepared T(1)-weighted images, it is essential that the single TI be chosen such that the longitudinal relaxation in all voxels of interest would have passed tau(null). SI(Eq) maps are also useful in eliminating confounders from MR images to allow obtaining SI values that reflect more faithfully the relaxation parameter (R(1)) sought.     

N-取代酰胺-二苯酮体系光化夺氢反应活泼自由基的ESR研究

本文用自由基捕捉剂2,3,5,6-四甲基亚硝基苯(ND)及苯亚甲基叔丁基氮氧化物(PBN)与ESR相结合的方法研究了十二种取代酰胺RC₆H₄NHC(0)CH₃(R-CH₃、Cl、Br、H、NO₂)、C₆H₅N(R)C(0)CH₃(R=CH₃、C₂H₅)及HC(0)NR₂(R-CH₃、C₂H₅)与二苯酮光化夺氢反应中的活泼自由基。结果表明: 1.对于RC₆H₄NHC(0)CH₃,二苯酮夺取氮上H形成R-C₆H₄NC(0)CH₃自由基。 2.对C₆H₅N(R)C(0)CH₃及HC(O)NR₂,二苯酮夺取与羰基相连的甲基氢、羰基上氢及与N相连碳上的氢分别形成 C₆H₅N(R)C(0)CH₂、C(0)NR₂、C₆H₅N(CHR')C(0)CH₃及。