甲酚红褪色分光光度法测定芬布芬的研究及其应用

在pH9.00的tris-HCl缓冲溶液中,甲酚红与芬布芬反应形成离子缔合物,使甲酚红溶液褪色.实验结果表明:最大褪色波长位于569.0nm,芬布芬浓度在0.05086～10.17μg/mL范围内遵循比尔定律,回归方程为ΔA=0.1702c+0.0107(c=μg/mL),相关系数为r=0.9996,表观摩尔吸光系数为4.537×104 L·mol-1·cm-1.据此建立了测定药物制剂和生物样品中芬布芬含量的褪色分光光度法,样品测定平均回收率为97.97%～101.6%.     

Towards 5G: Performance evaluation of 60 GHz UWB OFDM communications under both channel and RF impairments

Detailed analysis on the impact of RF and channel impairments on the performance of Ultra-Wideband (UWB) wireless Orthogonal Frequency Division Multiplexing (OFDM) systems based on the IEEE 802.15.3c standard, for high data-rate applications using the 60 GHz millimetre frequency band is presented in this paper. This frequency band, due to the large available bandwidth is very attractive for future and 5G wireless communication systems. The usage of OFDM at millimetre-wave (mmWaves) frequencies is severely affected by non-linearities of the Radio Frequency (RF) front-ends. The impact of impairments is evaluated, in terms of some of the most important key performance indicators, including spectral efficiency, power efficiency, required coding overhead and system complexity, Out-Of-Band Emissions (OOBEs), Bit Error Rate (BER) target and Peak Signal-to-Noise Ratio (PSNR). Additionally, joint distortion effects of coexisting Phase-Noise (PN), mixer IQ imbalances and Power Amplifier (PA) non-linearities, on the performance degradation of a mmWave radio transceiver, combined with various multipath fading channels, are investigated. Subsequently, the power efficiency of the system is evaluated by estimating values of the PA Output-Power-Backoff (OBO) needed to meet the requirements for the Transmit Spectrum Mask (TSM) and BER target. Finally, a comparison of the system overall performance between uncoded and coded OFDM systems combined with Quadrature Amplitude Modulations (16 and 64 QAM) and its maximum operable range are evaluated by transmitting a Full HD uncompressed video frame under five different RF impairment conditions over a typical LOS kiosk 60 GHz IEEE channel model.     

DSB optical mm-wave with signal only on optical carrier generated by embedded LiNbO3 Mach-Zehnder modulator

We have investigated the generation of the 40-GHz double-sideband optical millimeter (mm)-wave with signal carried only by its optical carrier via an embedded LiNbO₃ Mach-Zehnder modulator (LN-MZM). Since the optical carrier and its two first-order sidebands are dominant and their powers are well balanced, the first-order harmonic in the photocurrent gets maximal. As the optical mm-wave signal is transmitted along the fiber, there is no code outline distortion because the signal is only modulated on the optical carrier. Although the first-order harmonic shows the periodical fading effect when the optical mm-wave signal is transmitted along the fiber, its degradation on the radio-over-fiber link can be avoided by adjusting the position of the fading nodes via varying the main MZM bias voltage, and the signal still keeps much good eye diagram even after 50-km fiber transmission. The experimental results prove our theory.     

Studies on recoil proton tracks in NTA films with the T(d,n)He reaction

Recoil proton tracks in nuclear emulsion are counted by scanning them using strip, square or circular field of view of optical microscope. In this paper, the overestimate due to the edge effects in counting recoil proton tracks at different neutron energies produced from the T(d,n)⁴He reaction has been determined by measuring the true track density in NTA film. The overestimate has also been calculated using the measured value of the mean projected track length (L) in the film. The percentage of measured overestimates has been compared with those obtained by calculation and the results agree reasonably well. Fading effect in NTA film has been studied and found to be 22% more in the summer than in the winter season. A great reduction in fading rate could be achieved if the films are desiccated and sealed in highly pure dry nitrogen maintained at an over-pressure of 1000 Pa to reduce water vapour ingress. After the edge effect correction, the sensitivity of NTA film has been calculated from (1.72±0.08)×10⁻³ tracksn⁻¹ to (1.97±0.16)×10⁻³ tracksn⁻¹ in the neutron energy ranges from 15.91 to 18.88 MeV. The response was found to be from 0.24±0.02 trackscm⁻² permSv to 0.26±0.01 trackscm⁻² permSv in the same energy range.     

Investigation of regeneration effect of blue luminescence in NaCl using variable delay optically stimulated luminescence (VD-OSL)

Optically stimulated luminescence (OSL) of pure analytical sodium chloride (NaCl) was studied. Performing series of CW-OSL (continuous wave OSL) readouts it was found that subsequent CW-OSL decay, after some delay, starts from significantly higher intensity level than the final intensity of the previous readout. To study this ‘regeneration effect’ a new type of measurements was implemented – the variable delay OSL (VD-OSL) method. The idea of VD-OSL is explained – it allows to study OSL kinetics at very long time scale. VD-OSL data confirm coexistence of two effects in NaCl – regeneration and fading of the OSL signal. After partial CW-OSL readout, regeneration predominates in the short time scale of the order of 10³ s. Then, fading becomes dominant. The same measurements were applied to commonly used Al₂O₃:C material as well. Nevertheless, the results do not show such behavior at the studied time scale. Theoretical arguments are presented that the regeneration mechanism cannot be explained on the basis of the simple trap model.     

Attractors for the nonclassical diffusion equations with fading memory

We discuss long-time dynamical behavior of the nonclassical diffusion equation with fading memory when nonlinearity is critical. The existence and regularity of global attractors in weak topological space and strong topological space are obtained, while the forcing term only belongs to H⁻¹(Ω) and L²(Ω) respectively. The results in this part are new and appear to be optimal corresponding to the forcing term.     

SYNTHESIS AND PHOTOCHROMISM OF ACRYLIC ESTER COPOLYMERS BEARING PENDANT VIOLOGEN GROUPS

A series of acrylic ester copolymers with viologen group as pendant were synthesizedthrough the reaction of MMA-EBA (Ethenyl bromoacetate) copolymer with 4-(4'-pyridyl)-N-alkyl (or arylalkyl) pyridiniums. These viologen copolymers can exchange their anionwith NH_4PF_6 in methanol to improve their solubility in organic solvents such as DMFand acetone. Compared with the corresponding low molecular viologens, these viologencopolymers have relatively lower color development rate under UV light and fade fasterin air due to less affinity to photo-reductant and deficiency of association between theircation radicals. Their photofatigue resistant ability is also slightly better than that of lowmolecular vinlogens.     

次甲基蓝褪色光度法测定脱氧核糖核酸

研究了碱性染料次甲基蓝与脱氧核糖核酸的结合反应。在pH8.0～8.5的三羟甲基氨基甲烷-HCl介质中,次甲基蓝于630nm处有最大吸收,随着脱氧核糖核酸加入量的增加,其在630nm处的吸光度显著下降,下降程度与脱氧核糖核酸的量成正比。据此,建立了测定脱氧核糖核酸的新方法,方法的线性范围为0～7mg/L。该方法可用于合成样品分析。     

颜料层微观形貌对古代壁画褪色及显现影响

文物壁画在自然环境下产生褪色现象具有复杂性,严格意义上讲,人们无法重现自然环境下这种褪色发生的条件,但这并不妨碍人们研究其褪色原因的可能性和途径。通过实验来验证所提出机制的合理性,这也符合自然科学普遍采用的研究方法。提出颜料层微观形貌变化是引起壁画褪色的一种重要原因。胶料作为颜料层的连续相,当胶料分解时,颜料层微观形貌必然产生变化,为证明这种变化会引起颜料层褪色,而非颜料变化所致。建立了以具有较高热稳定性的赭石为颜料,以明胶作为粘接剂制成模拟的壁画颜料层。然后通过加热处理使胶料发生氧化分解,从而造成颜料层微观形貌发生变化,但赭石颜料依然稳定,期望证明在颜料赭石不发生变化时,由于颜料层微观形貌变化也可引起颜料褪色。实验通过煅烧壁画颜料层模拟样获得胶料降解的壁画模型,分别以SEM及多角度反射率光谱等技术,考察模拟样胶料降解前后表面微观形貌和光学性质变化。结果表明：壁画模拟样煅烧后,颜料层表面产生空隙结构,样品表面多角度反射率光谱表明煅烧后样品颜料层对可见光的反射增加而吸收降低,并观察到模拟样颜色淡化。以无色,难挥发,且不与颜料层发生化学反应的离子液体涂覆褪色样品表面,以上述技术表征涂覆处理前后颜料层表面微观形貌和表面光学性质变化,结果表明：离子液体填充了褪色样品表面颗粒间空隙,检测到样品表面对可见光的反射降低而吸收增加,观察到褪色样品的颜色加深。以上实验结果证明了推测合理性,即微观形貌变化确实会引起颜色变化。依据此原理以唐代墓室褪色壁画为例,进行了显现修复应用研究,其颜色显现效果显著。     

甲酚红褪色分光光度法测定吡罗昔康

用褪色分光光度法(测定药物制剂和生物样品中吡罗昔康含量。)在pH8.75的tris-HCl缓冲溶液中,甲酚红与吡罗昔康反应形成离子缔合物,使甲酚红溶液褪色,最大褪色波长位于570nm,吡罗昔康浓度在0.06628～11.60μg/mL范围内遵循比尔定律,回归方程为ΔA=0.1404c+0.0067,相关系数为r=0.9996,表观摩尔吸光系数为4.703×104L·mol-1.cm-1。据此建立了方法,样品测定平均回收率为97.51%～101.4%。