An Organoid for Woven Bone

Bone formation (osteogenesis) is a complex process in which cellular differentiation and the generation of a mineralized organic matrix are synchronized to produce a hybrid hierarchical architecture. To study the mechanisms of osteogenesis in health and disease, there is a great need for functional model systems that capture in parallel, both cellular and matrix formation processes. Stem cell-based organoids are promising as functional, self-organizing 3D in vitro models for studying the physiology and pathology of various tissues. However, for human bone, no such functional model system is yet available. This study reports the in vitro differentiation of human bone marrow stromal cells into a functional 3D self-organizing co-culture of osteoblasts and osteocytes, creating an organoid for early stage bone (woven bone) formation. It demonstrates the formation of an organoid where osteocytes are embedded within the collagen matrix that is produced by the osteoblasts and mineralized under biological control. Alike in in vivo osteocytes, the embedded osteocytes show network formation and communication via expression of sclerostin. The current system forms the most complete 3D living in vitro model system to investigate osteogenesis, both in physiological and pathological situations, as well as under the influence of external triggers (mechanical stimulation, drug administration).     

JackPot: A novel model to study the influence of current non-uniformity and cabling patterns in cable-in-conduit conductors

JackPot is a new model that is used to analyse how and to what extend current non-uniformity among strands in a cable-in-conduit conductor (CICC) affects its performance. The joints at the extremities of the CICCs in coils and short samples introduce a non-uniform current distribution among the strands. A detailed and quantitative study down to strand level is required to explain the involved phenomena, to understand their implications on short sample and coil tests and to provide adequate solutions for improvements. The model can be used to evaluate the influence of the joint design and to define its baseline requirements for short-sample qualification testing, and for optimum magnet performance of for example the ITER coils.JackPot is an electrical network model that simulates the interaction between the superconducting strands in the cable (following their precise trajectories), the interstrand contact resistances, the conduit, and the cable’s connection to the joints. The backbone of JackPot is its cable geometry model, from which all relevant properties are derived. All parameters are derived from well defined experimental measurements on conductor sections and joints, except the axial strain for Nb₃Sn strands, which is the only free parameter in the model.The simulations demonstrate that the current non-uniformity is the source for a number of observed phenomena. Another conclusion is that completely filling the bottom joints and upper terminations of a short sample with solder, opposed to only (partly) soldering the cable surface, improves short-sample testing significantly for qualifying the ITER type CICCs. This paper describes the model and gives a few examples of applications for its validation.     

Dependence of aortic pulse wave assessments on behavioural state in normal term fetus

To investigate any influence of behavioural states on the pulse waves in the descending aorta, 21 human fetuses were studied in utero in uncomplicated gestation at the age of 36-41 weeks. The fetal behavioural states were identified using two real-time scanners and one cardiotocograph. The aortic waveform data and pulse wave velocity (PWV) were recorded by means of two double phase-locking echo-trackers. The PWV of the fetal aorta was significantly lower in fetal behavioural state (FBS) 2F than in FBS 1F, when the fetus was apnoeic, and was also reduced in both states during fetal breathing. The calculated pulse pressure showed the same trend as the PWV. The fetal aortic end diastolic diameter and the pulse amplitude did not alter, when the two states changed. Our data suggest that the central haemodynamics in term fetuses are independently influenced by their behavioural state as well as by fetal breathing. The study of pulse waves in the fetal aorta should preferably be performed during apnoea in state 1F, when neither gross body movements nor breathing movements disturb the recording.     

河流样式框架：基于水文地貌评估支撑 河流景观的可持续修复与管理

河流景观是人类需求与自然基底相互作用形成的复 杂、多尺度嵌套的社会生态和水文地貌系统。基于水文地貌学 原理的“河流样式框架”为理解河流“形式与过程”之间的关 系提供了一个成熟的分析工具。系统梳理河流样式框架的基本 原则、具体步骤与核心内容,提出多尺度的空间层级划分、河 流样式与地貌单元的分类体系是该框架解释河流特征与河流行 为的核心方法。进而在流域尺度依据地貌状况与修复潜力评估 结果确定各个河段修复管理的优先次序,在河段尺度通过河流 演变轨迹分析预测河流的变化趋势。以期为“基于过程”的河 流景观修复设计与行动计划提供理论支持。     

Selection of elastomeric membranes for the removal of volatile organics from water

A wide range of homogeneous elastomeric membranes has been prepared using dicumylperoxide as a general cross-linking agent. The membranes have been used for both equilibrium sorption measurements and steady-state pervaporation experiments to study solution–diffusion phenomena in the removal of volatile organic components from aqueous solutions. Pervaporation experiments have been performed under identical hydrodynamic conditions in order to fix the boundary layer mass transfer coefficient at a constant and known value. For comparison of the permeabilities of different pervaporation membrane materials, this is of utmost importance. A wide range of selectivity factors up to a value of 100,000 are obtained, whereas usually the permeabilities for the organic component are in the range of 10^?10?10^?9m²/s and 10^?14?10^?12m²/s for water. The permeation and sorption data obtained for the various elastomers have been related to the chemical and physical nature of the elastomers through the solubility parameter and the glass transition temperature, respectively. Both diffusional and sorption effects seem to be important, determining the water-transport behavior in the elastomeric membranes. The solubility of the organic component appears to be independent of this combined solubility parameter. Differences in the permeabilities of the organic component can primarily be ascribed to structural parameters in the membrane material, like degree of unsaturation and presence of steric side groups. © 1993 John Wiley & Sons, Inc.     

The role of production control in the development of burnout

Burnout is an increasingly important problem in modern work organizations. Few studies, however, have explicitly applied an adequate theoretical understanding of the performance of modern organizations. This article aims to initiate both a discussion of this phenomenon and higher-quality research into the emergence of burnout based on an understanding of the economic-technological rationalization and control (management control) of production and service processes. In applying production control, both technical and bureaucratic, group and attitudinal control systems are increasingly integrated. This so-called systematic control strategy is one of the major causes of burnout. The cumulative effect of an increasing workload combined with reduced resources due to economic considerations and technocratic implementation of production control is assumed to be relevant to the development of burnout. The authors' propositions apply to service workers in human service organizations and to key workers in enterprises using flexible specialization combined with self-directed work groups.     

Switching off propene hydrogenation in the direct epoxidation of propene over gold–titania catalysts

Low gold-loaded gold–titanium catalysts with very small gold nanoparticles for the direct epoxidation of propene have a remarkably high epoxidation activity. A disadvantage, however, is that these catalysts in certain cases also have a very high activity for the unwanted hydrogenation of propene to propane. The addition of a small amount of carbon monoxide to the feed gas can completely switch off this propene hydrogenation, while at the same time also reducing the rate of direct water formation. The co-ordination environment of titanium plays an important role in propene hydrogenation.     

基于森林景观恢复策略的庄园遗产景观设计探寻——以荷兰海德兰省巴克塞比克地区为例

庄园遗产景观是指包含花园和农业用地的历史乡村庄园集群。在气候变化、工业发展和快速城市化的背景下,庄园遗产景观正面临水生态环境失衡、空间碎片化和文化特征消失等挑战,而这些挑战只能从区域规划尺度去应对。以荷兰海德兰省巴克塞比克地区为例,在考虑地方景观异同的同时,以景观自身特性为基底,结合未来发展趋势,进一步诠释了一种旨在提升庄园遗产景观韧性的多尺度景观设计方法。发现森林砍伐为地域空间变化的主要因素之一,它对水系统与生态多样性造成了负面影响。基于在区域尺度上对庄园遗产景观历史发展的分析,森林景观恢复(FLR)作为主要设计策略,旨在从不同尺度上对“退化的”景观进行生态功能修复并提升人类福祉。这种新的空间设计方法将在不同尺度上促进文化遗产景观发展。     

Does the fluid elasticity influence the dispersion in packed beds?

Reasons are given why the axial dispersion in a gas flowing through a packed bed may be influenced by the elasticity - or compressibility - of the fluid. To support this hypothesis, experiments have been done in a packed column at pressures from 0.13 to 2.0 MPa. The elasticity E of a gas is proportional to the pressure P and the compressibility to 1/P. The axial dispersion coefficients as determined were found to be a function of the pressure in the packed bed in the turbulent flow region of 3 < Re_p < 150 if the Bodenstein number is plotted as a function of the particle Reynolds number. This is shown to be an artifact. The pressure influence is eliminated, if Bo_{m, ax} is plotted versus the ratio of the kinetic forces over the elastic forces ?u²/E. Regrettably, Bo_{m, ax} seems to be independent of ?u²/E. For the moment we only can conclude that Bo_{m, ax} in the turbulent region is a unique function of the velocity of the gas which flows through the packed bed. Although the fact that a constant Bo value is obtained when plotted against ?u²/E, the experimental results are so intriguing we wanted to make them public already now. The experimental work proceeds.