Sulphur mineralization and adsorption in soils

Summary Studies were conducted to determine the comparative sulphur mineralizing capacity of selected Malaysian and Iowan soils and to determine the amounts of available and adsorbed sulphate in a number of Malaysian soils. Results of the mineralization study indicated that more sulphur mineralised from Malaysian soils although their average contents of total sulphur were lower compared to Iowan Soils. For both sets of soils, significant correlations between contents of organic carbon and total sulphur existed indicating that most of the sulphur was in organic combination. Phosphate solution consistently extracted higher quantities of sulphate in comparison to chloride solution in the Malaysian surface soils implying that a portion of the sulphate existed in adsorbed form. Adsorption of sulphate in soils was found to be dependent on concentration of sulphate added and followed the Langmuir adsorption isotherm.     

Cytoplasmic streaming inParamecium

Summary Certain species ofParamecium demonstrate rotational cytoplasmic streaming, in which most cytoplasmic particles and organelles flow along permanent route, in a constant direction. By means of novel methods of immobilization, observation and recording, some dynamic properties of cytoplasmic streaming have been described. It was found that the velocity profiles of coaxial layers of cytoplasm have a (parabolic) paraboidal shape and the mean output of cytoplasm flow in different examined zones of streaming is constant. As the consequence of randomly distributed elementary propulsion units within the cytoplasm, particles, which serve as markers of movement, exhibit movements of a saltatory nature; this form of movement is seen inParamecium streaming only in cases of error due to polarization of the saltating particles. Interaction of actin filaments and myosin is likely to occur under specific conditions in microcompartments of cytoplasm where local solations are generated eventually leading to contractions which might propagate on gelated neighbouring areas. Places of elementary contractions are scattered. Therefore the motile effect appears as streaming. Rotational cytoplasmic streaming inParamecium may serve as a convenient model for the study of the dynamics and function of cytoplasmic motility.     

A simple process for the isolation of epithelial cells from bacteria-contaminated samples using anchoring molecules

A simple and efficient tool to isolate epithelial cells from bacteria-contaminated samples has been developed using two different microparticles functionalized with chemical molecules. The epithelial cells could be captured simply by biocompatible anchors for membranes (BAM), consisting of poly(ethylene glycol) functionalized with oleyl-chain-conjugated NHS (N-hydroxysuccinimide) on glass microparticles, whereas bacteria were adsorbed on 3-aminopropyltrimethoxysilane (ATPS)-functionalized magnetic microparticles. In the case of samples highly contaminated with bacteria, epithelial cells were not isolated successfully by both of the single BAM- and antibody-functionalized microparticles. Therefore, serial isolation steps of these two different chemical functionalized microparticles were introduced. The concentration of bacteria was decreased dramatically by using APTS-functionalized magnetic particles prior to the isolation of epithelial cells by BAM microparticles. With these serial processes, successful isolation of epithelial cells was achieved from bacteria-contaminated epithelial samples. The applicability of this method was verified with bacteria-contaminated intestinal samples biopsied from a BALB/C mouse for primary cell cultivation.     

HepG2细胞中线粒体形状的动态变化

目的:研究HepG2细胞中线粒体形状动态变化过程中的功能变化及其初步分子机制。方法:HepG2细胞经过HBSS缓冲液饥饿处理后,使用线粒体氧化磷酸化解偶联剂CCCP、脂肪酸受体GPR40/120激动剂GW9508、脂肪酸油酸OA和钙离子载体Ionomycin等4种不同药物处理,通过共聚焦显微镜观察和流式细胞分析的手段检测细胞中线粒体形状和功能发生的改变。然后,通过基因沉默Drp1,Mff或者Fis1蛋白,初步研究调控线粒体形状改变的分子机制。结果:经过CCCP和GW9508处理细胞中产生甜甜圈线粒体,而OA和Ionomycin处理产生球状线粒体。CCCP,OA和Ionomycin使线粒体去极化,CCCP、GW9508、OA或者Ionomycin单独处理在一定程度上影响细胞中活性氧化簇ROS。甜甜圈线粒体产生由Drp1介导,而球状线粒体形成依赖于Drp1和Mff。结论:线粒体的形态与其功能相互联系,Drp1和Mff蛋白对于细胞线粒体形状动态改变过程中形状的调整和适应具有很重要的作用。     

Dynamic control of toxic natural product biosynthesis by an artificial regulatory circuit

To mimic the delicately regulated metabolism in nature for improved efficiency, artificial and customized regulatory components for dynamically controlling metabolic networks in multiple layers are essential in laboratory engineering. For this purpose, a novel regulatory component for controlling vanillin biosynthetic pathway was developed through directed evolution, which was responsive to both the product vanillin and substrate ferulic acid, with different capacities. This regulatory component facilitated pathway expression via dynamic control of the intracellular substrate and product concentrations. As vanillin is an antimicrobial compound, low pathway expression and vanillin formation levels enabled better cell growth at an early stage, and the product feedback-activated pathway expression at later stages significantly improved biosynthesis efficiency. This novel multiple-layer dynamic control was demonstrated effective in managing the trade-off between cell growth and production, leading to improved cell growth and vanillin production compared to the conventional or quorum-sensing promoter-controlled pathway. The multiple-layer dynamic control enabled by designed regulatory components responsive to multiple signals shows potential for wide applications in addition to the dynamic controls based on biosynthetic intermediate sensing and quorum sensing reported to date.     

Modeling of dynamical systems through deep learning

This review presents a modern perspective on dynamical systems in the context of current goals and open challenges. In particular, our review focuses on the key challenges of discovering dynamics from data and finding data-driven representations that make nonlinear systems amenable to linear analysis. We explore various challenges in modern dynamical systems, along with emerging techniques in data science and machine learning to tackle them. The two chief challenges are (1) nonlinear dynamics and (2) unknown or partially known dynamics. Machine learning is providing new and powerful techniques for both challenges. Dimensionality reduction methods are used for projecting dynamical methods in reduced form, and these methods perform computational efficiency on real-world data. Data-driven models drive to discover the governing equations and give laws of physics. The identification of dynamical systems through deep learning techniques succeeds in inferring physical systems. Machine learning provides advanced new and powerful algorithms for nonlinear dynamics. Advanced deep learning methods like autoencoders, recurrent neural networks, convolutional neural networks, and reinforcement learning are used in modeling of dynamical systems.     

A rapid enantioseparation system of capillary electrochromatography modified by electrostatic adsorption with transfersomes

Transfersomes were a special kind of nanomaterials with higher deformability and flexibility. A rapid method for coated-column preparation using anionic transfersomes as a coating material by electrostatic adsorption was developed. With carboxymethyl-β-cyclodextrin added in running buffer as the chiral selector, the capillary electrochromatography enantioseparation system based on the transfersomes-coated column modified by electrostatic adsorption was established for the first time. Propranolol and metoprolol acted as model drugs to evaluate the enantioseparation performance, these two basic drugs achieved baseline separation with satisfactory resolution and selection factor in this transfersomes-electrochromatography system but only partial separation in bare column system. In order to get the optimal separation condition, concentration of chiral selector, buffer pH, and applied voltage were systematically investigated. A rapid and efficient enantioseparation electrochromatography system was established and showed that transfersomes as the stationary phase could efficiently improve chiral separation effect.     

壳聚糖改性竹炭对铜吸附性能研究

为了提高竹炭去除废水中重金属离子能力,采用交联法设计合成新型的磁性壳聚糖改性竹炭复合吸附剂,并采用傅里叶红外光谱对改性竹炭复合吸附剂进行表征,同时开展不同Cu2+初始浓度、吸附剂投加量、吸附时间、pH和温度等因素对Cu2+吸附去除率的影响。结果表明,吸附效率与Cu2+初始浓度和吸附剂投加量成正效应;吸附平衡时间约8 h;在作用温度范围内,吸附效率随温度升高而上升;pH为7时吸附效果最好。振荡条件吸附效果优于静置处理。该结果为废水重金属深度处理及水环境保护提供依据。     

Obtaining maximum muscle excitation for normalizing shoulder electromyography in dynamic contractions

Muscle specific maximal voluntary isometric contractions (MVIC) are commonly used to elicit reference amplitudes to normalize electromyographic signals (EMG). It has been questioned whether this is appropriate for normalizing EMG from dynamic contractions. This study compares EMG amplitude when shoulder muscle activity from dynamic contractions is normalized to isometric and isokinetic maximal excitation as well as a hybrid approach currently used in our laboratory. Anterior, middle and posterior deltoid, upper and lower trapezius, pectoralis major, latissimus dorsi and infraspinatus were monitored during (1) manually resisted MVICs, and (2) maximum voluntary dynamic concentric contractions (MVDC) on an isokinetic dynamometer. Dynamic contractions were performed (a) at 30°/s about the longitudinal, frontal and sagittal axes of the shoulder, and (b) during manual bi-rotation of a tilted wheel at 120°/s. EMG from the wheel task was normalized to the maximum excitation from (i) the muscle specific MVIC, (ii) from any MVIC (MVIC_ALL), (iii) for any MVDC, (iv) from any exertion (maximum experimental excitation, MEE). Mean EMG from the wheel task was up to 45% greater when normalized to muscle specific isometric contractions (method i) than when normalized to MEE (method iv). Seventy-five percent of MEE’s occurred during MVDCs. This study presents an 20 useful and effective process for obtaining the greatest excitation from the shoulder muscles when normalizing dynamic efforts.