一种带有精准调谐结构的有源RC低通滤波器的设计

提出了一种带有精准调谐结构的有源RC低通滤波器的设计方案,其截止频率为5MHz,并在0.18μm标准CMOS工艺线上流片得到验证.调谐精度达到（-1.24%, +2.16%) ,测试中得到验证.调谐系统所占芯片面积仅为主滤波器面积的1/4.调谐系统完成调谐功能后会自动关闭,降低了功耗以及对主滤波器的串扰.以50Ω作为源阻抗,滤波器带内3阶交调量（IIP3）好于16.1dBm.滤波器输入参考噪声为36μVrms.滤波器群延迟时间波动测试结果为24ns.滤波器功耗为3.6mW.带有这种调谐结构的滤波器容易被实现,可以用于很多无线低中频应用中,例如全球定位系统、全球通和码分多址等芯片系统中.     

K-shell X-ray cross-section ratios for 1H, 4He and 6Li projectiles on targets from fluorine to titanium

Experimental K X-ray emission ratios have been measured for nine elements ranging from F to Ti (9 ? Z₂ ? 22) using ¹H⁺, and ⁶Li⁺ projectiles. The experimental ratios are in fair agreement with theoretical predictions for the velocity range studied, $\text{?}{}_{\mathrm{k}}\text{\$}\text{?}\text{1}$.     

The effect of the electrode gap on breakdown in liquid dielectrics

It is a well known fact that the breakdown voltage of an insulating liquid increases nonlinearly with increasing electrode gap. Under nonuniform field dc conditions two breakdown voltages are determined depending on the electrode polarity. Using point-plane geometries, with gaps of 5 mm or larger, one finds that typical transformer oils have higher breakdown voltages when the point is negative than when it is positive. Recently, perfluorinated polyethers have been found to produce opposite results when using average gap sizes of 5 to 10 mm. To elucidate this situation a study of the effect of gap size on breakdown voltage has been undertaken. The results show that for the polyethers at larger gaps the sequence is reversed. These observations are explained in terms of the respective streamer developments in these liquids and the relative stability of their negative ions. In the case of the conventional hydrocarbon type oils, the positive streamer usually grows slightly faster than the negative one, but the streamer inception voltages of both are rather similar. In the case of perfluorinated polyethers the positive streamers move at least 10× faster than the negative ones, but they require much higher inception voltages than negative ones. At gaps ≳12 mm and the associated higher applied voltages this breakdown at negative polarity occurs at higher voltages than at the positive one. The negative ions of the perfluoro compounds are much more stable than those of conventional hydrocarbons. The discharge of the negatively charged perfluoro ions requires much higher fields than do those of conventional hydrocarbons. The implications of these observations are discussed in some detail     

Prognostic value of ploidy of primary tumour and nodal secondaries in colorectal cancers

Tumour ploidy is of prognostic value in colorectal cancer, DNA aneuploid tumours having a worse outlook. Nearly all studies have concentrated on the DNA content of the primary tumour. We have examined the ploidy of the primary tumour and its lymph node metastases in 71 cases of Dukes' stage C disease, to see whether this provides greater prognostic information than the primary alone. Analysis was performed using formalin-fixed, paraffin-embedded tumour sections. Ploidy of primary and metastases was different in 20 cases (28%), aneuploid nodes being seen with diploid primaries and vice versa. Ploidy of both the primary (chi 2 = 4.86, P = 0.03) and secondary (chi 2 = 4.86, P = 0.03) tumours predicted survival in univariate analysis. Combining the ploidy of primary and nodes, three prognostic groups could be defined--diploid primaries with diploid metastases (hazard relative to both aneuploid, 0.36) had significantly better survival than cases where the ploidy of the primary and nodes were mixed (relative hazard 0.47-0.56), which did better than cases with aneuploid primary and nodes. This study demonstrates that ploidy variation between primary and secondary tumours is common, and better prognostic information may be gained by studying both.     

Activated sludge characteristics in relation to stable foam formation

This paper examines the hydrophobicity and the surface charge of a range of foaming and nonfoaming activated sludges, together with an appraisal of the species involved. The results show that the solids in foaming sludges possess a higher hydrophobicity than those in nonfoaming sludges. The data also indicate that there are two distinct hydrophobicity/surface charge trends, depending on whether the sludges are foaming or nonfoaming. Sludges in which Nostocoida limicola was the dominant species did not conform to these patterns. In addition, the stability of the foam formed by these sludges was significantly lower.     

Angiotensin-(1-7) and the rat aorta: modulation by the endothelium

Peptide metabolites of angiotensin I and II are active components of the renin-angiotensin system. One such peptide is angiotensin-(1-7), which has been shown to be present in various tissues and has properties distinct from those of angiotensin II. We examined the effects of angiotensin-(1-7) on endothelium-intact and denuded rat aorta. Second, we evaluated whether an interaction occurred between angiotensin-(1-7) and angiotensin peptides, as well as noradrenaline. Finally, we addressed whether the responses to angiotensin-(1-7) were mediated by an AT1 receptor. Angiotensin-(1-7) produced concentration-dependent relaxations of the rat aorta that were significantly greater in endothelium-intact preparations (81.1 +/- 18.9% and 29.6 +/- 2.9% for intact and denuded, respectively). Angiotensin-(1-7) inhibited responses generated to angiotensin I, II, III, and noradrenaline. In endothelium-denuded preparations, angiotensin-(1-7) produced a rightward shift of the concentration-effect curves to angiotensin II and noradrenaline. In addition, the inhibition against angiotensin I and II was significantly greater in endothelium-intact preparations [mean median inhibitory concentration (IC50) values for endothelium-intact preparations, 1.25 x 10(-9) M and 1.57 x 10(-9) M for angiotensin I and II, respectively; and for endothelium-denuded preparations, 1.77 x 10(-8) M and 1.17 x 10(-8) M for angiotensin I and II, respectively). Losartan did not affect relaxations in endothelium-intact preparations but caused a significant potentiation of the relaxation by angiotensin-(1-7) in denuded preparations. We conclude that angiotensin-(1-7) is a component of the renin-angiotensin system that acts to modulate the pressor effects of angiotensin II and noradrenaline.     

Atopic dermatitis in early infancy predicts allergic airway disease at 5 years

The two geminal ethyl groups in the succinic acid moiety of CGP57698 (4-[3-(7-fluoro-2-quinolinyl-methoxy)phenyl-amino]-2,2-diethyl-4-oxo- butanoic acid) are responsible for the high in vitro and in vivo potency of this peptidoleukotriene antagonist of the quinoline type. The synthesis and structure activity relationships of CGP57698 and its analogs are described.     

Cord blood-IgE as risk factor and predictor for atopic diseases

PURPOSE: To investigate whether radiation-induced micronucleus formation as expressed by the cytochalasin-blocked Mn-assay correlates with cellular radiosensitivity measured by a colony assay in primary fibroblast cultures from cancer patients. MATERIALS AND METHODS: Studies were made on skin fibroblasts from 36 breast cancer patients. The micronucleus assay was performed using treatment with cytochalasin-B to create binucleate cells. Response was scored in terms of the percentage of binucleate cells with micronuclei, also as the number of micronuclei per binucleate cell. The data were related to previously published results of cell survival measurements on these cell lines. RESULTS: Neither endpoint for micronucleus formation showed a correlation with radiosensitivity by the colony assay. The fraction of fibroblasts that reach mitosis without micronuclei also failed to correlate with cell survival. CONCLUSIONS: Among these primary fibroblast cell lines radiation-induced micronucleus formation was not associated with radiosensitivity as measured by a colony assay.     

Suppression of the Keto‐Emission in Polyfluorene Light‐Emitting Diodes: Experiments and Models

The spectral characteristics of polyfluorene (PF)‐based light‐emitting diodes (LEDs) containing a defined low concentration of either keto‐defects or of the polymer poly(9,9‐octylfluorene‐co‐benzothiadiazole) (F8BT) are presented. Both types of blend layers were tested in different device configurations with respect to the relative and absolute intensities of green and blue emission components. It is shown that blending hole‐transporting molecules into the emission layer at low concentration or incorporation of a suitable hole‐transporting layer reduces the green emission contribution in the electroluminescence (EL) spectrum of the PF:F8BT blend, which is similar to what is observed for the keto‐containing PF layer. We conclude that the keto‐defects in PF homopolymer layers mainly constitute weakly emissive electron traps, in agreement with the results of quantum‐mechanical calculations.