Fermentation diagnosis by multivariate statistical analysis

During the course of fermentation, online measuring procedures able to estimate the performance of the current operation are highly desired. Unfortunately, the poor mechanistic understanding of most biologic systems hampers attempts at direct online evaluation of the bioprocess, which is further complicated by the lack of appropriate online sensors and the long lag time associated with offline assays. Quite often available data lack sufficient detail to be directly used, and after a cursory evaluation are stored away. However, these historic databases of process measurements may still retain some useful information. A multivariate statistical procedure has been applied for analyzing the measurement profiles acquired during the monitoring of several fed-batch fermentations for the production of erythromycin. Multivariate principal component analysis has been used to extract information from the multivariate historic database by projecting the process variables onto a low-dimensional space defined by the principal components. Thus, each fermentation is identified by a temporal profile in the principal component plane. The projections represent monitoring charts, consistent with the concept of statistical process control, which are useful for tracking the progress of each fermentation batch and identifying anomalous behaviors (process diagnosis and fault detection).     

用于无创产前诊断的SRY基因高灵敏高特异检测方法研究

通过检测母体外周血中胎儿游离DNA(cffDNA)的SRY基因,确定胎儿性别,可评估胎儿性连锁遗传病的发病风险,降低病儿出生率.本研究建立了高灵敏、高特异、闭管检测不易污染的实时荧光PCR偶联核酸侵入反应方法用于SRY基因的检测.通过优化反应体系中的检测探针浓度、FEN1酶用量、Taq酶用量及预扩增退火温度,确定了最佳的反应条件,即检测探针浓度为250 nmol/L、FEN1酶用量为7.5 U、Taq酶用量为0.5 U、预扩增退火温度为67℃.在最佳反应条件下,实现对含量低至4%(4 copies/μL)的模拟样本的检测,并成功检测两例孕期分别为9周和10周的临床实际样本.结果表明,所建立的方法可用于母体外周血cffDNA的SRY基因检测,为临床开展基于SRY基因的无创产前诊断提供了新方法.     

癌变与正常直肠组织的核磁共振氢谱差异的研究

核磁共振(NMR)波谱法是一种表征分子结构、组成变化的有效手段,能够得到生物组织中的核酸、蛋白质、脂类和糖类等生物大分子的含量、分子的空间排列和结构特征等信息,可以从分子水平上研究肿瘤与对照组织之间的差别,更深入地揭示肿瘤的发生、发展中产生的各种分子水平变化。文章对9例直肠癌组织及癌旁正常组织进行了核磁共振氢谱的测定。结果表明,直肠正常和癌变组织的核磁共振氢谱存在显著的差异,这可以通过对谱图特征峰区域积分面积相对比值的差别看出来。直肠正常组织核磁共振氢谱中A0.9/A3.0,A1.3/A3.0,A2.0/A3.0,A1.3/A0.9及A4.1/A3.0值较相应的癌组织偏大,直肠癌组织核磁共振氢谱中A3.2/A3.0值较相应正常直肠组织偏大。通过这些差异核磁共振氢谱技术有可能发展成为早期诊断直肠癌组织的一种方法。     

Laser-Induced Fluorescence at 488 nm Excitation for Detecting Benign and Malignant Lesions in Stomach Mucosa

This work aims the detection of the histopathologic alterations of in vitro human gastric mucosa using spectral informations from laser-induced fluorescence spectroscopy (LIFS) technique with excitation at 488 nm (argon laser). A total of 108 biopsies with endoscopic diagnosis of gastritis and gastric cancer were obtained at the antral gastric region, from 35 patients with dyspeptic digestive complaints. The biopsies were collected during the endoscopic examination. On each biopsy fragment the autofluorescence spectrum was collected in two random points, through a fiber-optic catheter coupled to the excitation laser. The fluorescence emission spectra collected by the fibers were directed to the spectrograph and detected by the CCD camera. The spectra were then separated in groups (N, normal; LI, light inflammation; MI, moderated inflammation; CA, adenocarcinoma), based on the histopathology. The ratio between the emission wavelengths 550 and 600 nm was used as a diagnostic parameter. Analysis of fluorescence spectra was able to identify the normal tissue from adenocarcinoma lesions with 100% of sensibility and specificity. The ratio intensities between inflammation (light and moderated), although presented significantly statistical differences when compared to the normal mucosa, do not furnish enough sensibility and specificity for use as an identification method due to high variations. LIFS, with excitation of 488 nm, could be used in the differentiation of normal tissue and neoplasic lesions, assisting a less invasive diagnosis.     

Imaging through scattering media using characteristics of the temporal distribution of transmitted laser pulses

An object consisting of small inhomogeneities embedded in a highly scattering solution was imaged using measurements of the time-resolved transmitted intensity of picosecond pulses of near-infrared light. Data acquisition involved translating the object in two orthogonal directions across the beam, and recording the temporal distribution of transmitted light at a series of discrete positions. Images were constructed from the total transmitted light, the first four moments of the temporal distribution, and from parameters derived from a comparison of the distribution with an analytical model, based on the diffusion approximation to the radiative transfer theory. The results show that the optical properties along a line-of-sight between source and detector influence some of these characteristics more than others.     

组态软件在冷水机组实时监视与故障诊断方面的应用

先进行冷水机组监测参数的选择和数据采集的硬件配置,然后在MCGS组态软件的组态环境下进行组态工程的开发,组成冷水机组实时监视与故障诊断系统。该系统实现对冷水机组的运行参数实时监视、参数超限报警和故障人工智能诊断的功能;便于严密监视设备的运行工况,减少故障发生;也便于在设备发生故障后分析和判断故障产生的原因。     

采用氧合血红蛋白吸收带的漫反射光谱比率R（540）/R（575）检测浅表性膀胱癌

采用氧合血红蛋白在540和575 nm吸收带的漫反射光谱比率(R540/R575)对人浅表性膀胱癌进行了鉴别诊断,实验采用带积分球附件的分光光度计获取组织的漫反射光谱。结果表明:正常膀胱的粘膜/粘膜下层组织的漫反射光谱比率(R540/R575)在组织离体后2 h的平均值为111%,3 h的平均值为107%,4 h的平均值为104%,5 h的平均值为102%,而浅表性的膀胱癌的粘膜/粘膜下层组织的漫反射光谱比率(R540/R575)在组织离体后2 h的平均值为98.4%,3 h的平均值为95.5%,4 h的平均值为93.1%,5 h的平均值为91.6%,正常膀胱与浅表性膀胱癌的粘膜/粘膜下层组织在组织离体后2,3,4和5 h的漫反射光谱比率(R540/R575)均有显著性的差异(p<0.05),分别为12.6%,11.5%,10.9%和10.4%。这结论为快速、低成本、非入侵的浅表性膀胱癌的光活检提供了一种新的方法。     

淀粉自由基弛豫发光

为了研究淀粉自由基的变化规律,以生物光子辐射理论为基础.根据化学发光的动力学模型,建立了淀粉自由基的发光动力学方程,并根据自由基发光强度与自由基浓度的关系,通过分析得到了淀粉自由基的湮没方程,得到了光强随时间的变化函数.通过拟合发现,函数在不同温度下随时间的变化曲线与实验曲线的相关系数都在0.98以上,能很精确地刻画自由基的弛豫发光规律.     

Three-dimensional non-destructive optical evaluation of laser-processing performance using optical coherence tomography

We demonstrate the use of optical coherence tomography (OCT) as a non-destructive diagnostic tool for evaluating laser-processing performance by imaging the features of a pit and a rim. A pit formed on a material at different laser-processing conditions is imaged using both a conventional scanning electron microscope (SEM) and OCT. Then using corresponding images, the geometrical characteristics of the pit are analyzed and compared. From the results, we could verify the feasibility and the potential of the application of OCT to the monitoring of the laser-processing performance.     

A preliminary in vitro assessment of polymer-shelled microbubbles in contrast-enhanced ultrasound imaging

This paper focuses on the use of poly (vinyl alcohol)-shelled microbubbles as a contrast agent in ultrasound medical imaging. The objective was an in vitro assessment of the different working conditions and signal processing methods for the visual detection (especially in small vessels) of such microbubbles, while avoiding their destruction. Polymer-shelled microbubbles have recently been proposed as ultrasound contrast agents with some important advantages. The major drawback is a shell that is less elastic than that of the traditional lipidic microbubbles. Weaker echoes are expected, and their detection at low concentrations may be critical. In vitro experiments were performed with a commercial ultrasound scanner equipped with a dedicated acquisition board. A concentration of 100 bubbles/mm³, excitation pressure amplitudes from 120 kPa to 320 kPa, and a central frequency of 3 MHz or 4.5 MHz were used. Three multi-pulse techniques (i.e., pulse inversion, contrast pulse sequence based on three transmitted signals, and contrast pulse sequence in combination with the chirp pulse) were compared. The results confirmed that these microbubbles produce a weaker ultrasound response than lipidic bubbles with a reduced second-order nonlinear component. Nevertheless, these microbubbles can be detected by the contrast pulse sequence technique, especially when the chirp pulse is adopted. The best value of the contrast-to-tissue ratio was obtained at an excitation pressure amplitude of 230 kPa: although this pressure amplitude is higher than what is typically used for lipidic microbubbles, it does not cause the rupture of the polymeric contrast agent.