基于MBF参数模型的安全完整性等级定量评估

介绍了安全完整性等级验证的相关内容,并对系统发生危险失效因素进行分析;在引入MBF(Multiple Beta Factor)参数模型的基础上,定量计算系统发生共因失效的概率,并研究系统发生独立危险失效的概率及其影响;最后给出应用实例进行验证。结果表明:本文方法不仅更接近工业生产中安全仪表系统冗余结构的实际情况,也大大简化了计算,弥补了马尔可夫模型法分析计算过程复杂的缺陷。     

Construction of pH/reduction dual responsive MSN-HAgel containing HApt for tumor targeting carriers

In this study, a pH/reduction dual responsive carrier containing 42nt-nucleic acid HApt based on mesoporous silica nanoparticles (MSNs) was designed. Two kinds of low molecular weight oligomeric hyaluronic acid (HA) were used to graft onto MSN for better drug encapsulation. Crosslinked MSN-HA₃₀₀₀gel and MSN-HA₁₁₀₀₀gel were prepared by crosslinking the HA chain through the sulfhydrylization of the carboxyl group on the HA side chain. An appropriate amount of sulfhydryl nucleic acid (HApt-SH) was added during the crosslinking reaction, which realized the targeting ability and apoptosis function to cancer cells overexpressing the HER2 receptor. Crosslinked HA had a good effect on decreasing the side effect of DOX that the drug leakage was less than 20% under a normal body environment. However, it could realize rapid and efficient drug release in a tumor environment. As to the release of HApt, it exhibited a good response to GSH. The cytotoxicity test showed that HApt contained in HAgel had a great targeting effect and significant cytotoxicity to SKBR3 cells. As a whole, this MSN-HAgel enabled the combination of gene therapy and chemotherapy, showing the synergistic effect of “1 + 1 > 2”, providing a novel idea for cancer treatments.

A dual-responsive MSN-based nanocarrier for the combination of gene therapy and chemotherapy in cancer treatments.     

Selecting features for BCI control based on a covert spatial attention paradigm

Covert attention to spatial locations in the visual field is a relatively new control signal for brain–computer interfaces. Previous EEG research has shown that trials can be classified by thresholding based on left and right hemisphere alpha power in covert spatial attention paradigms. We reexamine the covert attention paradigm based on MEG measurements for fifteen subjects. It is shown that classification performance can be improved by applying sparse logistic regression in order to select a subset of the sensors specific to each subject as the basis for classification. Furthermore, insight is gained into how classification performance changes as a function of the length of the attention period and as a function of the number of trials. Classification performance steadily increases as the length of the attention period over which is averaged is increased, although this does not necessarily translate into higher bit rates. Good classification performance using early components of the attention period may be related to evoked response. With regard to the number of used trials, classification performance became maximal after 150 samples had been obtained, requiring a training time of approximately eleven minutes under the current experimental paradigm.     

一种用于噪声估计的改进最小值搜索方法

含噪语音短时功率谱的最小值搜索是噪声估计的基础。为了提高非平稳噪声估计的准确性,减小噪声水平上升时的噪声估计延时,提出了一种同时使用大、小两个搜索窗进行并行搜索的方法,最小值搜索的最终结果由两个并行搜索结果和基于噪声分类的语音存在二值判决共同决定。实验结果表明：对于高度非平稳的噪声,该方法能够有效地减小噪声估计的延时问题,显著提高增强后语音的质量。     

克雷伯氏肺炎杆菌生产1,3-丙二醇代谢途径中的酶活变化

考察了不同条件下克雷伯氏肺炎杆菌(Klebsiella.pneumoniae)合成1,3-丙二醇(1,3-PD)的3种关键酶(甘油脱氢酶(GDH)、1,3-PD氧化还原酶(PDOR)及甘油脱水酶(GDHz))的表观酶活变化。结果显示:这3种酶的酶活变化与Klebsiella.pneumoniae的1,3-PD代谢不完全相关。用SDS-PAGE电泳分析上述不同发酵条件下酶活变化,结果显示不同于3种酶的蛋白条带,Mr约为4.0×104位置的蛋白条带有明显的变化,这可能与菌体代谢过程相关,结论有待进一步深入研究。     

盐酸硫胺(VB1)催化合成四氢咔唑类化合物

1,2,3,4-四氢咔唑类衍生物广泛应用于医药领域。在盐酸硫胺（VB₁）催化作用下,苯肼盐酸盐和环己酮在乙醇中反应,可以简便、高产率地得到四氢咔唑类化合物。将不同基团取代的环己酮和含有吸电子或供电子基团的苯肼用VB₁进行底物扩展,大部分目标产物的产率在90%以上,证实在合成四氢咔唑的反应中,VB₁是一种温和、高效、环保型的催化剂。对VB₁进行回收再利用,催化效率没有明显降低。     

Identification of a novel ene reductase from Pichia angusta with potential application in (R)-levodione production

Asymmetric reduction of electronically activated alkenes by ene reductases (ERs) is an attractive approach for the production of enantiopure chiral products. Herein, a novel FMN-binding ene reductase (PaER) from Pichia angusta was heterologously expressed in Escherichia coli BL21(DE3), and the recombinant enzyme was characterized for its biocatalytic properties. PaER displayed optimal activity at 40 °C and pH 7.5, respectively. The purified enzyme was quite stable below 30 °C over a broad pH range of 5.0–10.0. PaER was identified to have a good ability to reduce the C C bond of various α,β-unsaturated compounds in the presence of NADPH. In addition, PaER exhibited a high reduction rate (k_cat = 3.57 s⁻¹) and an excellent stereoselectivity (>99%) for ketoisophorone. Engineered E. coli cells harboring PaER and glucose dehydrogenase (for cofactor regeneration) were employed as biocatalysts for the asymmetric reduction of ketoisophorone. As a result, up to 1000 mM ketoisophorone was completely and enantioselectively converted to (R)-levodione with a >99% ee value in a space–time yield of 460.7 g L⁻¹ d⁻¹. This study provides a great potential biocatalyst for practical synthesis of (R)-levodione.

Asymmetric reduction of electronically activated alkenes by ene reductases (ERs) is an attractive approach for the production of enantiopure chiral products.     

IFA和FA联合方法在化工过程监控中的应用

工业过程数据具有高斯和非高斯混合分布的特点。独立因子分析（IFA）采用一维高斯混合模型拟合任意的因子分布,因此可以处理高斯和非高斯混合的问题。虽然在给定因子数的前提下变分IFA算法可以有效地缩短建模时间,但是独立因子数的选择仍然需要较长的计算时间。此外,若IFA的因子数选择不当,会造成部分因子的信息遗留在观察变量的残差中,导致GSPE监控指标的监控性能变差。为了解决IFA在实际应用中存在的问题,本文结合了IFA和FA方法。首先使用FA辅助IFA选取独立因子数,以进一步减小IFA建模时间;其次使用FA对IFA的残差进行再处理,以解决由于独立因子数选择不当造成的问题。最后将该方法应用于田纳西-伊斯曼（TE）过程和乙烯裂解炉过程的监控中,实验结果验证了该联合方法的有效性。