棕榈仁冷榨饼造粒浸出制油的工艺研究

为改善棕榈仁进料饼粕质量,提高棕榈仁油浸出效率,通过对压榨饼进行造粒后再浸出制油的工艺进行了探索性研究,系统地考察了物料水分、模板孔径对造粒过程的影响,比较分析了造粒料与未造粒料的浸出效果。试验结果表明:造粒过程中机械力可以有效的破碎压榨过程没有破碎的棕榈仁,提高物料的渗透性和浸出效果。对于含油18%的棕榈仁压榨饼造粒,其最佳造粒水分为9.5%～10.5%,造粒模板孔径4mm,浸出粕的残油在0.86%～0.93%之间,比压榨饼直接浸出可降低粕中残油0.7%～0.8%。     

Multi-scale structure finite element analyses of damage behaviors of multi-axial warp-knitted composite materials subjected to quasi-static and high strain rate compressions

This paper reports a multi-scale structure finite element modeling scheme to analyze the damage behaviors of biaxial multi-layer warp-knitted composite materials subjected to quasi-static and high strain rate compressions. The multi-scale structure model includes: (1) a micro/meso/macro structure model with periodic boundary conditions for homogenizing the heterogeneous fiber/resin system into unit cells, and (2) a macroscopic rate-dependent plasticity model for the knitting composite materials combined with critical damage area failure theory, which accounts for the stiffness degradation and failure strength of the material. The finite element results from the model provide the locations of stress propagation, the stress distribution, and the progressive failure behavior within the biaxial multi-layer warp-knitted composite materials. The effects of the knitted yarns and the element number sensitivity of the macro-scale model have also been discussed.     

Co-production of Lactic Acid and <Emphasis Type="Italic">Lactobacillus rhamnosus</Emphasis> Cells from Whey Permeate with Nutrient Supplements

Lactic acid and cell production from whey permeate by Lactobacillus rhamnosus with different nutrient supplements were investigated in this study. Yeast extract was identified as the most effective nutrient affecting lactic acid production. Increase in inoculum size from 0.05% to 1% (v/v) resulted in a substantial increase in lactic acid productivity from 0.66 to 0.83 g L⁻¹ h⁻¹ (P < 0.001). The optimal temperature for lactic acid production was 37 °C, while the highest cell production was obtained at 42 °C. When whey permeate and yeast extract concentrations were 6.8% (w/v) and 3 g L⁻¹, respectively, lactic acid productivity reached 0.85 g L⁻¹ h⁻¹ after 48-h cultivation, which is 3.40 times of those without nutrient supplements.     

二次纤维聚集态结构的研究进展

为了研究二次纤维的角质化机理并提出抑制方法,实现二次纤维的高效绿色循环利用,综述了基于共结晶角质化机理的纤维素聚集态结构的研究现状和进展,介绍了纤维素聚集态结构模型和氢键链接方式,着重介绍了目前纤维素聚集态结构研究和氢键研究的进展,综述了目前纤维素聚集态研究手段的多样化:计算机分子模拟、广角X衍射衍射(XRD)、交叉极化/魔角旋转固体核磁共振13C(CP/MAS13C NMR),同步辐射XRD衍射、中子衍射和傅里叶红外(FT-IR)。研究内容从对天然纤维素的基本建模深入到分子链水平的原子链接、氢键模式的研究,研究手段经历了从使用单一仪器发展到多种仪器手段辅助表征的过程。纤维素聚集态结构的研究将是二次纤维角质化机理研究以及纤维素化学研究的重要课题。     

超声波协同过氧化氢氧化法制备低分子质量大豆多糖

以大分子质量的大豆多糖为原料,探讨制备低分子质量可溶性大豆多糖的降解方法及工艺。通过初步对比超声波法、过氧化氢法和超声波协同过氧化氢氧化降解法,发现超声波协同过氧化氢氧化法降解效果最好。继而对这一降解方法进行了单因素和正交试验研究,研究结果表明:在超声波功率100 W的条件下,大豆多糖超声波协同过氧化氢氧化降解法的最佳工艺为过氧化氢浓度8%,70℃降解1.5 h,大豆多糖的分子质量可以由1.6×105降解到1.09×104。     

Effects of organic carbon supply rates on uranium mobility in a previously bioreduced contaminated sediment

Bioreduction-based strategies for remediating uranium (U)-contaminated sediments face the challenge of maintaining the reduced status of U for long times. Because groundwater influxes continuously bring in oxidizing terminal electron acceptors (O2, NO3(-)), it is necessary to continue supplying organic carbon (OC) to maintain the reducing environment after U bioreduction is achieved. We tested the influence of OC supply rates on mobility of previously microbial reduced uranium U(IV) in contaminated sediments. We found that high degrees of U mobilization occurred when OC supply rates were high, and when the sediment still contained abundant Fe(III). Although 900 days with low levels of OC supply minimized U mobilization, the sediment redox potential increased with time as did extractable U(VI) fractions. Molecular analyses of total microbial activity demonstrated a positive correlation with OC supply and analyses of Geobacteraceae activity (RT-qPCR of 16S rRNA) indicated continued activity even when the effluent Fe(II) became undetectable. These data support our hypothesis on the mechanisms responsible for remobilization of U under reducing conditions; that microbial respiration caused increased (bi)carbonate concentration and formation of stable uranyl carbonate complexes, thereby shifted U(IV)/U(VI) equilibrium to more reducing potentials. The data also suggested that low OC concentrations could not sustain the reducing condition of the sediment for much longer time. Bioreduced U(IV) is not sustainable in an oxidizing environment for a very long time.     

Research on image segmentation of Miao costume patterns based on the RSKP-UNet model北大核心CSCD

The Miao nationality is the sixth largest ethnic group in China which has a history of thousands of years. It has created a unique material culture and spiritual culture in its development process and the Miao costume is a highly condensed collection of the material and spiritual culture of the Miao nationality. As one of the unique symbols of Miao culture the Miao costume has profound cultural heritage and cultural connotations. The patterns of the Miao costume are particularly eye-catching as they not only symbolize the wisdom of the Miao people in thousands of years of production and life but also symbolize the pursuit of the good spirit of the Miao people. However under the impact of modern pop culture and foreign culture these cultural symbols are gradually disappearing. In order to protect and inherit them the Miao costume pattern segmentation has become the most important work. However the Miao costume pattern segmentation is quite difficult. At present there are few studies on the extraction classification identification and preservation of the features of Miao costume pattern segmentation. With the excellent segmentation performance of the U-Net model and the advantages of easy deployment the paper improves the basic structure of the U-Net model and proposes a Miao costume pattern segmentation algorithm based on the RSKP-UNet Residual Selective-Kernel Parallel U-Net model. The algorithm adds Residual modules in the encoder part of the U-Net model to improve the feature extraction capability of the model and embeds the SKNet modules and ParNet modules in the decoder part to enhance the feature expression capability of the model. The paper uses evaluation metrics to measure the segmentation performance of the model and compares it with four segmentation models based on deep learning. The paper not only combines the current research focus-deep learning and attention mechanism but also introduces the Lovász-hinge loss function to effectively solve the problem of class imbalance in the Miao costume patterns. The RSKP-UNet model is better than other models in various segmentation indicators. Compared with the benchmark model U-Net the Dice coefficient IoU precision recall and accuracy are improved by 6. 98% 11. 07% 2. 89% 6. 75% and 3. 92% . The segmentation algorithm proposed in this paper realizes the extraction of the element content of the Miao costume patterns through image segmentation of Miao costume patterns which can be used to build the Miao costume pattern database in this way thus helping designers relevant researchers and organizations to provide research foundation and completing the protection and inheritance of the Miao costume culture. The paper also provides some reference for the segmentation research of other minority costume patterns. © 2022 Authors. All rights reserved.     

“迷魂药”揭秘

人们经常听说“蒙汗药”或者“迷魂药”——在许多中国古典小说中．外国小说中．武侠小说中又或者在一些现实的刑事案件中。这种“迷魂药“或“蒙汗药”效果神奇，人若吃了．便会昏睡过去犹如死人：或者神志迷离．任人摆布…… 究竟是什么药．竟有如此神奇的效果？     

Effects of temperature,pH and light on the stability of aloin A and characterisation of its major degradation products

This study explored the stability and degradation products of aloin A under varying pH, temperature and light conditions usually encountered in processing. The stability of aloin A was significantly affected by temperature and pH. The content of aloin A decreased by more than 90% within 12 h at 50 °C and within 6 h at 70 °C, respectively. A significant decrease in stability was also observed at higher pHs. At pH 8.0, less than 2% of aloin A remained within 12 h. However, aloin A exhibited good stability at acidic pH levels with 94% remaining at pH 2.0 for 14 days. Light exerted no influence on the stability during the experimental period (14 days). Aloe‐emodin, elgonica‐dimers A and B were characterised as major degradation products of aloin A at pH 5.0 or below, and elgonica‐dimers were mainly formed at 4 °C as well. 10‐hydroxyaloins A and B were found under any condition except at pH 2.0 and 3.0, and they were mainly formed under high temperature, neutral‐basic and any light conditions.