搅拌槽流场的实验研究

利用二维激光多普勒测速仪在内径为２５０ｍｍ的搅拌槽内对ＤＴ叶轮和ＰＴ叶轮进行了流场测试，获得了不同几何参数的叶轮在不同工况下的二维时均速度场和湍流强度、雷诺应力、剪切速率分布。为进一步研究搅拌器的流动特性，开发新型搅拌叶轮提供了可靠的实验依据。     

Direct numerical simulation of turbulent pipe flow

Fully developed turbulent pipe flow at low Re-number is studied by means of direct numerical simulation (DNS). In contrast to many previous DNS's of turbulent flows in rectangular geometries, the present DNS code, developed for a cylindrical geometry, is based on the finite volume technique rather than being based on a spectral method. The statistical results are compared with experimental data obtained with two different experimental techniques. The agreement between numerical and experimental results is found to be good which indicates that the present DNS code is suited for this kind of numerical simulations.     

An improved sample-and-hold reconstruction procedure for estimation of power spectra from LDA data

Techniques for deriving the auto or power spectrum (PSD) of turbulence from laser Doppler anemometry (LDA) measurements are reviewed briefly. The low pass filter and step noise errors associated with the sample-and-hold process are considered and a discrete version of the low pass filter for the resampled signal is derived. This is then used to develop a procedure by which the PSD estimates obtained from sample and hold measurements can be corrected. The application of the procedures is examined using simulated data and the results show that the frequency range of the analysis can be extended beyond the Nyquist frequency based on the mean sample rate. The results are shown to be comparable to those obtained using the method of Nobach et al. (1998) but the new procedures are more straightforward to implement. The technique is then used to determine the PSD of real LDA data and the results are compared with those from a hot wire anemometer.     

MS/MS-Based Molecular Networking: An Efficient Approach for Natural Products Dereplication

Natural products (NPs) have historically played a primary role in the discovery of small-molecule drugs. However, due to the advent of other methodologies and the drawbacks of NPs, the pharmaceutical industry has largely declined in interest regarding the screening of new drugs from NPs since 2000. There are many technical bottlenecks to quickly obtaining new bioactive NPs on a large scale, which has made NP-based drug discovery very time-consuming, and the first thorny problem faced by researchers is how to dereplicate NPs from crude extracts. Remarkably, with the rapid development of omics, analytical instrumentation, and artificial intelligence technology, in 2012, an efficient approach, known as tandem mass spectrometry (MS/MS)-based molecular networking (MN) analysis, was developed to avoid the rediscovery of known compounds from the complex natural mixtures. Then, in the past decade, based on the classical MN (CLMN), feature-based MN (FBMN), ion identity MN (IIMN), building blocks-based molecular network (BBMN), substructure-based MN (MS2LDA), and bioactivity-based MN (BMN) methods have been presented. In this paper, we review the basic principles, general workflow, and application examples of the methods mentioned above, to further the research and applications of these methods.     

一种改进的激光二极管纵向泵浦固体激光器的腔模设计方法

以空间相关的速率方程理论为基础，提出了一种改进的激光二极管纵向泵浦固体激光器的设计方法，给出了在一定泵浦耦合方式下，激光腔模尺寸和输出耦合率最佳值的选取依据，以采用不同耦合系统的端面泵浦Ｎｄ：ＹＡＧ激光器设计实例，相应的实验结果与有理论计算符合得较好。     

Adjustment and evaluation of an LDA probe for accurate flow measurement

An LDA probe with optimized measuring volume was obtained based on repeated adjustments of a preconfigured LDA system with a calibrated spinning disc. A retriggerable pulse-width-and-time-delay module was used to trigger and freeze favorable Doppler bursts. After a repeated beam-steering procedure and a fringe-pattern analysis, we found that the variation of fringe spacing throughout the measuring volume was reduced from 3% to 0.28%, such that the adjusted probe gave more accurate measurements. To verify this applicability in velocity calibration, the fringe spacing of the adjusted LDA measuring volume was treated as a velocity coefficient, and its mean and measurement uncertainty was experimentally estimated. Analysis shows that the expanded uncertainty of the coefficient was 0.10% at the 95% level of confidence for both the components of the LDA. The results demonstrated that the adjusted LDA system was qualified to perform accurate flow measurement.     

Insights on colorectal cancer relapse by infrared microscopy from anastomosis tissues: Further analysis

The relapse rate for colorectal cancer (CRC) is high and has a significant impact on survival and quality of life. CRC relapse can be local, at the anastomosis, or distant, as evidenced by metastasis. Reducing the local recurrence of the disease may improve patient survival and quality of life. This could be achieved by determining safe surgical margins of the removed cancerous lesion during colorectal surgery. The detection of abnormal crypts is essential for diagnosis of the spread of CRC and its effective management.Our overall goal in this study is to evaluate and suggest which biological molecules in the cell contribute more to the classification procedure. This may provide clues for biologically understanding the principle of CRC recurrence. Longitudinal sections from normal anastomosis tissues obtain from CRC patients during surgery were used. Fourier transform infrared spectroscopy (FTIR) in tandem with multivariate analysis, principal component analysis (PCA), and linear discriminant analysis (LDA) were used to achieve this purpose.Colonic longitudinal sections are preferable for studying the colonic tissues quantitatively. It was possible to differentiate between the three categories: local recurrence, distant recurrence and control with a 100% success rate.     

Incomplete similarity of a plane turbulent wall jet on smooth and transitionally rough surfaces

This study assesses the hypothesis of incomplete similarity for a plane turbulent wall jet on smooth and transitionally rough surfaces. Typically, a wall jet is considered to consist of two regions: an inner layer and an outer layer. The degree to which these two regions reach equilibrium with each other and interact to produce the property of self-similarity remains an open question. In this study, the analysis of the outer and inner regions indicates that each region is characterised by a half-width which exhibits its own distinct dependence on the streamwise distance x from the slot, and a single self-similar structure for both regions does not exist. More specifically, the inner and outer layers of the wall jet exhibit different scaling laws, which results in two self-similar mean velocity profiles, both of which retain a dependence on the slot height H. As such, incomplete similarity of the wall jet on smooth and transitionally rough surfaces is confirmed by this study. In addition, comparison of the experimental results for the transitionally rough surface with the smooth wall case indicates that the surface roughness modifies the development of the mean velocity profile in both the inner and outer regions, although the effect on the outer region is relatively small and close to the experimental uncertainty.