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Systematic characterization of cleanroom-free fabricated macrovalves,demonstrating pumps and mixers for automated fluid handling tuned for organ-on-chip applications

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Microsystems & Nanoengineering 2022年第3期8卷 163-176页

作者： Elsbeth G.B.M.Bossink Anke R.Vollertsen Joshua T.Loessberg-Zahl andries d.van der meer Loe l.Segerink Mathieu Odijk BIOs Lab on a Chip Group MESA+instituteTechnical Medical CenterMax Planck Institute for Complex Fluid DynamicsUniversity of TwenteEnschedeThe Netherlands Applied Stem Cell Technologies Group Technical Medical CenterUniversity of TwenteEnschedeThe Netherlands

Integrated valves enable automated control in microfuidic systems,as they can be applied for mixing,pumping and compartmentalization *** automation would be highly valuable for applications in organ-on-chip(OoC)***,OoC systems typically have channel dimensions in the range of hundreds of micrometers,which is an order of magnitude larger than those of typical microfluidic *** most-used fabrication process for integrated,normally open polydimethylsiloxane(PdMS)valves requires a reflow photoresist that limits the achievable channel *** addition,the low stroke volumes of these valves make it challenging to achieve flow rates of microliters per minute,which are typically required in OoC ***,we present a mechanical'macrovalve'fabricated by multilayer soft lithography using micromilled direct *** demonstrate that these valves can close off rounded channels of up to 700μm high and 1000μm ***,we used these macrovalves to create a peristaltic pump with a pumping rate of up to 48μL/min and a mixing and metering device that can achieve the complete mixing of a volume of 6.4μL within only 17 *** initial cell culture experiment demonstrated that a device with integrated macrovalves is biocompatible and allows the cell culture of endothelial cells over multiple days under continuous perfusion and automated medium refreshment.

关键词： pumping mixer pump

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Rangeland degradation Impacts on Vegetation Cover, Soil Properties and Ecosystem Functioning in an Arid and Semi-Arid Climate, South Africa

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Journal of Geoscience and Environment Protection 2022年第2期10卷 10-32页

作者： Hermias Cornelius van der Westhuizen Christiaan Cornelius du Preez Hendrik andries Snyman Free State department of Agriculture and Rural development Glen South Africa department of Soil Crop and Climate Sciences University of the Free State Bloemfontein South Africa department of Animal Wildlife and Grassland Sciences University of the Free State Bloemfontein South Africa

The negative effect of soil erosion and soil compaction is well documented for the purpose of optimum rangeland functioning, while the impact of rangeland degradation on effective soil depth is seldom quantified. The aim of this study was to quantify the response of vegetation cover and soil properties, particularly effective soil depth and soil texture to rangeland degradation. Forty-one farms were sampled in the arid and semi-arid climate of South Africa. Within these farms, data was collected over a vegetation degradation gradient. Results showed a significant decline in relative basal cover (94% ± 15% to 39% ± 17%) and soil depth (90% ± 14% to 73% ± 24%) as rangeland degraded. Soil texture changes over the degradation gradients vary for different homogeneous vegetation types. Indications regarding the loss of a functioning rangeland ecosystem were also demonstrated, using objective long-term relations between rangeland conditions and grazing capacity. The study highlights the importance of sustainable rangeland management practices to reduce the loss in effective soil depth and to ensure the sustainable utilization of the rangeland ecosystem. These results can probably extrapolate to other arid and semi-arid rangelands worldwide.

关键词： Rangeland Condition Soil degradation Effective Soil depth Soil Erosion Soil Compaction Ecosystem Functioning

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Multi-photon quantum cutting in Gd_(2)O_(2)S:Tm^(3+) to enhance the photo-response of solar cells

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Light(Science & Applications) 2015年第1期4卷 144-151页

作者： de-Chao Yu Rosa Martin-Rodriguez Qin-Yuan Zhang andries Meijerink Freddy T Rabouw State Key Laboratory of Luminescence Materials and devices and Institute of Optical Communication Materials South China University of TechnologyGuangzhou 510641China debye Institute for Nanomaterials Science Utrecht UniversityP.O.Box 800003508 TA Utrechtthe Netherlands

Conventional photoluminescence(PL)yields at most one emitted photon for each absorption ***(or quantum cutting)materials can yield more than one photon by virtue of energy transfer processes between luminescent *** this work,we introduce Gd2O2S:Tm^(3+) as a multi-photon quantum *** can convert near-infrared,visible,or ultraviolet photons into two,three,or four infrared photons of,1800 nm,*** cross-relaxation steps between Tm^(3+) ions that lead to quantum cutting are identified from(time-resolved)PL as a function of the Tm^(3+) concentration in the crystal.A model is presented that reproduces the way in which the Tm^(3+) concentration affects both the relative intensities of the various emission lines and the excited state dynamics and providing insight in the quantum cutting ***,we discuss the potential application of Gd2O2S:Tm^(3+) for spectral conversion to improve the efficiency of next-generation photovoltaics.

关键词： downconversion infrared emission quantum cutting solar cells spectral conversions

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