自耦合射流强化掺混的数值研究

针对同向两股气流掺混的某一特定物理模型,对自耦合射流作用下的气流掺混过程进行了数值模拟研究.与未施加自耦合射流激励的掺混过程相比,自耦合射流周期性的吹/吸诱导流场内产生复杂的大尺度涡系结构,使得同向两股气流形成对流型混合,有效缩减了主流核心区长度;相对于在燃烧室单侧放置激励器的方式,双侧自耦合射流激励时温度均匀分布线较...     

Effects of several different flux enhancing chemicals on filterability and fouling reduction of membrane bioreactor (MBR) mixed liquors

The main objective of this work was to determine the effectiveness of various chemicals on filterability and fouling reduction in MBR mixed liquors. Different lab-scale experiments were conducted with a total of 7 different additives (3 cationic polymers (MPL30, MPE50, KD452), a biopolymer (Chit), a starch (Sta), and 2 metal salts (FeCl₃, PACl)). Initially, batch shaker tests were performed for each additive to determine the optimum dosages in terms of soluble microbial products (SMP) removal. Then, short-term filtration trials and critical flux tests were performed. All tested additives were able to remove SMP, but at different extent; 33, 45, 51, 36, 38, 54, and 56% for MPL30, MPE50, KD452, FeCl₃, PACl, Chit, and Sta, respectively. The cationic polymer KD452 exhibited the best performance in terms of the extent of SMP removal and the required dosage. All tested cationic polymers, starch and chitosan significantly reduced fouling rates and increased permeability values. At their optimum dosages, the cationic polymers MPE50, MPL30 and KD452 provided 96, 80 and 74% reductions in fouling rates, respectively. The enhancements in critical flux achieved by MPL30, MPE50, KD452, FeCl₃, PACl, Chit, and Sta were 38, 46, 38, 14, 14, 0, and 22% in comparison with raw mixed liquor. Cationic polymers increased critical flux values to levels above 50 L m⁻² h⁻¹. SMP removal from MBR mixed liquors and further improvement in filtration performance and fouling control did not always correlate. Overall, based on the lab-scale tests conducted, cationic polymeric additives were found to be favorable over the other additives due to their steady and successful performance in fouling control. The performance of cationic polymers was independent of small variations in dosing, while for other additives over- or under-dosing showed detrimental effects on filterability.     

丙氨酸酯衍生物的合成及其对吲哚美辛的经皮促渗活性

以N,N-二乙基-l-丙氨酸为原料,N,N'-二环己基碳二亚胺为缩合剂,4-甲氨基吡啶为催化剂,合成了7个新型的2-(N,N'-二乙基氨基)丙酸酯(1a~1g),其结构经1H NMR,MS(ESI)和元素分析表征。研究了其对药物吲哚美辛的体外经皮促渗活性。结果表明:1g对吲哚美辛的经皮促渗活性最好(94.2%)。     

混合增效分析试剂对不稳定配合物显色体系应用探讨——1 Cd~(2+)-GBHA体系

Cd~(2+)与乙二醛-双-(2-羟基缩苯胺)所成配合物在水溶液中极不稳定,立即退色,无法测定其吸光度.本文试验了混合增效分析试剂(Triton X-100+PVA+CTMAB)对此体系的增稳、增敏和增溶作用.在此三种增效分析试剂的协同作用下,使体系可稳定20min以上,表观摩尔吸光系数达1.12×10~4 L.mol~(-1)·Cm~(-1),有可能应用于分析实践.并初步探讨了有关机理.     

Enhanced emission of the laser generated plume in Ar gas

We report an effect of enhanced emission of laser generated plume in gas ambi-ent.Nonreactive argon gas was used in the experiment of UV laser ablation of copper plate.The emission of Cu atoms from the plume was increased more than the times.The emission in-tensity is sensitive to the gas pressure,but in a certain region of gas pressure,the enhanced ef-fect can be controlled stably.For the emission lines from other element,Zn,in the plume,the intensities are subjected to the same factor of increasement.     

Tagging saccharides for signal enhancement in mass spectrometric analysis

MALDI-MS provides a rapid and sensitive analysis of large biomolecules such as proteins and nucleic acids. However, oligo- and polysaccharides are less sensitive in MS analysis partly due to their neutral and hydrophilic nature to cause low ionization efficiency. In this study, four types of oligosaccharides including aldoses, aminoaldoses, alduronic acids and α-keto acids were modified by appropriate tags at the reducing termini to improve their ionization efficiency. Bradykinin (BK), a vasoactive nonapeptide (RPPGFSPFR), containing two arginine and two phenylalanine residues turned out to be an excellent MS signal enhancer for maltoheptaose, GlcNAc oligomers and oligogalacturonic acids. In the MALDI-TOF-MS analysis using 2,5-dihydroxybenzoic acid (2,5-DHB) as the matrix, the GalA4-BK and GalA5-BK conjugates prepared by reductive amination showed the detection limit at 0.1 fmol, i.e. ～800-fold enhancement over the unmodified pentagalacturonic acids. The remarkable MS enhancement was attributable to the synergistic effect of the basic arginine residues for high proton affinity and the hydrophobic property phenylalanine residues for facile ionization. A tetrapeptide GFGR(OMe) and an arginine linked phenylenediamine (H(2) N)(2) Ph-R(OMe) were thus designed to act as potent tags of oligosaccharides in MS analysis. Interestingly, concurrent condensation and lactonization of α2,8-linked tetrasialic acid (SA4) was carried out with (H(2) N)(2) Ph-R(OMe) to obtain a quinoxalinone derivative, which showed > 200-fold enhancement over unmodified SA4 in the MALDI-TOF-MS analysis.     

Comparison of methods to enhance flame ionization detector (FID) signals in gas chromatography

The performances of some numerical methods to improve the signal to noise ratio are compared and applied to enhance noisy signals obtained in gas chromatography with capillary columns and a flame Ionization detector. Several methods have been considered: cutoffs In the Fourier transform of the recorded signal; real time numerical filtering; theoretical model curve fitting; and the correlation of a chromatogram recorded from a pseudorandomly injected sample with the pseudorandom injection function. Numerical real time filtering is shown to be the most convenient method when the main periodic component of the noise has been determined by Fourier analysis.     

强化对流传热场协同唯象机制及其控制

根据对流传热强度与流体中存在的各种内场及其外场的关系,从唯象上阐明了降低温度边界层厚度、增加流体扰动和增加近壁面速度梯度的强化对流传热方法的物理机制,其本质是控制流体中内场及其外场之间的相互协同。给出了当流体中存在内场和外场时强化对流传热场协同控制方法,以此可指导发展强化对流传热单元的新方法。     

基于独立分量分析的红外线列扫描图像处理方法

独立分量分析(Independent component analysis,ICA)作为一种有效的盲源分离方法,其目的是从由传感器收集到的混合信号中分离出相互独立的源信号,使得这些分离出来的信号之间尽可能的相互独立。针对红外线列扫描图像,提出了一种基于ICA的图像增强方法,该方法能够有效地去除红外线列扫描图像的非均匀性干扰。阐述了ICA的基本原理,介绍了基于负熵判据的FastICA算法,给出了该方法的具体实现步骤及相应的实验处理结果。结果表明,利用该方法能够达到图像增强的目的。     

Using low frequency and intensity ultrasound to enhance start-up and operation performance of Anammox process inoculated with the conventional sludge

A lab-scale ultrasound enhancing Anammox reactor (R1) was established and irradiated once a week by ultrasound with the optimal parameter (frequency of 25 kHz, intensity of 0.2 W cm⁻² and exposure time of 3 min) obtained by batch experiments. R1 and the controlled Anammox reactor (R2) without exposure to the ultrasound were operated in parallel. The start-up period of Anammox process (53 days) in R1 was shorter than that (61 days) in R2. The nitrogen loading-enhancing period (day 53-day 135) in R1 was also shorter than that (day 61-day 151) in R2. At the end of the nitrogen loading-enhancing period, NLR (0.76 kg N m⁻³ d⁻¹) and NRR (0.68 kg N m⁻³ d⁻¹) of R1 were both higher than NLR (0.66 kg N m⁻³ d⁻¹) and NRR (0.56 kg N m⁻³ d⁻¹) of R2. Moreover, The stability of Anammox process in R1 was better than that in R2. The results demonstrated that the periodical irradiation of ultrasound enhanced the start-up and operational performance of Anammox reactor. Microbial community analysis indicated that the ultrasound accelerated the microbial succession from some other bacteria to Anammox bacteria so that shorten the start-up period of Anammox process from the conventional activated sludge. It also indicated that the ultrasound strengthened the competitive advantage of Candidatus Kuenenia stuttgartiensis in Anammox bacteria of the mature sludge so as to enhance the nitrogen removal performance of the Anammox reactor under the operation condition of high nitrogen loading.