Living organisms enhance their survival rate by excreting fluids at their surface, but man-made materials can also benefit from liquid secretion from a solid surface. Known approaches to secrete a ...liquid from solids are limited to passive release driven by diffusion, surface tension, or pressure. Remotely triggered release would give active control over surface properties but is still exceptional. Here, we report on an artificial skin that secretes functional fluids by means of radiofrequency electrical signals driven by dielectric liquid transport in a (sub-)microporous smectic liquid crystal network. The smectic order of the polymer network and its director determine the flow direction and enhance fluid transport toward the surface at pre-set positions. The released fluid can be reabsorbed by the skin using capillary filling. The fluid-active skins open avenues for robotic handling of chemicals and medicines, controlling tribology and fluid-supported surface cleaning.
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•Liquid ejection by RF electric field•Release of functional liquid droplets•Spontaneous reabsorption of the secreted liquid at field-off state
We developed an artificial skin that administers fluids by a triggered release. The principle is based on a radio frequency actuated liquid crystal polymer network that squeezes out the initially locked liquid from its nano-/microsized pores. We demonstrate that chemical reagents or medicine can also be released upon secretion of the fluids. The polymer skin can be refilled by absorption in a controlled manner. We anticipate this trigger-induced liquid secretion to be integrated into soft robotics and microfluidics, for instance to control chemical reactions, drug delivery, and to tune surface wettability and adhesion.
An artificial organic skin that can secrete liquid and wet its surface is demonstrated. The secretion is triggered by an alternating electric field at radio frequency. The polymer skin is constructed of a porous liquid crystal polymer network with the embedded dielectric liquid. The electric field accumulates the liquid in between the electrodes. By network contraction, the liquid is ejected at the surface of the polymer skin.
Purpose
Patients with Hirschsprung disease (HD) can have persistent obstructive symptoms after resection of the aganglionic segment. If obstructive symptoms are treated inadequately, this may lead to ...recurrent faecal stasis and impaction, and may result in severe distension of the bowel. A permanently distended bowel which not responds to conservative treatment may be an indication for redo surgery. The aim of this study is to describe our experiences and the short-term results of a novel technique: longitudinal antimesenteric resection with a longitudinal anastomosis.
Methods
We reviewed the medical records of our three patients who underwent longitudinal resection of severe distended bowel. This technique aims to improve defecation by improving faecal passage and is characterized by resection of the antimesenteric side of the distended intestinal segment, followed by plication with a longitudinal anastomosis. In this paper, this novel technique is described in detail, as well as short-term outcomes.
Results
All patients had an uneventful recovery after longitudinal antimesenteric resection. During follow-up, the functional outcomes were excellent, with a large improvement of bowel function. All patients were continent for faeces, and treated with low-dose laxatives or occasional preventive irrigation in one patient. There were no more complaints of persistent constipation or soiling.
Conclusion
Longitudinal resection is a surgical redo-procedure offering large benefits for patients with Hirschsprung disease with distended bowel after primary surgery.
The purpose of this study was to evaluate the impact of postoperative complications and the presence of a stoma on long-term quality of life in patients with rectal cancer.
Consecutive patients with ...an adenocarcinoma of the rectum who underwent surgery at Maastricht University Medical Center or VieCuri Medical Center between 2003 and 2005 were included in this study. Data on surgical treatment and complications were collected. Severe postoperative complications were classified according to a standardized complication severity score. Quality of life was assessed by use of the European Organization for Research and Treatment of Cancer core and colorectal cancer-specific quality-of-life questionnaires.
One hundred seventy patients received a questionnaire, and 121 (71%) responded. Of the responders, 33 (27.3%) patients suffered from severe postoperative complications. The median follow-up was 36 months. In the univariate analysis, patients with severe postoperative complications had a lower score on physical functioning (73 vs. 85, P = 0.031) and higher scores on pain (17 vs. 0, P = 0.025) and fatigue (33 vs. 22, P = 0.036). Stoma construction (n = 51) was associated with a higher global health status (83 vs. 75, P = 0.019), and these patients reported fewer gastrointestinal problems (P = 0.001).
Severe postoperative complications seem to be associated with several lower quality-of-life subscores over the long term. In contrast, a stoma is associated with improved global health status and leads to fewer gastrointestinal complaints. In patients prone to complications, it may be sensible to avoid creating a low anastomosis and to construct a permanent stoma immediately.
Summary
Plant roots selectively forage for soil nutrients when these are heterogeneously distributed. In turn, effects of plant roots on biotic and abiotic conditions in the soil, which result in ...so‐called plant–soil feedback can be heterogeneously distributed as well, but it is unknown how this heterogeneity affects root distribution, nutrient uptake and plant biomass production. Here, we investigate plant root distribution patterns as influenced by spatial heterogeneity of plant–soil feedback in soil and quantify consequences for plant nitrogen uptake and biomass production.
We conditioned soils by four grassland plant species to obtain ‘own’ and ‘foreign’ soils that differed in biotic conditions similar as is done by the first phase of plant–soil feedback experiments. We used these conditioned soils to create heterogeneous (one patch of own and three patches of foreign soils) or homogeneous substrates where own and foreign soils were mixed. We also included sterilized soil to study the effect of excluding soil biota, such as pathogens, symbionts and decomposers. We supplied 15N as tracer to measure nutrient uptake.
In nonsterile conditions, most plant species produced more biomass in heterogeneous than in homogeneous soil. Root biomass and 15N uptake rates were higher in foreign than own soil patches. These differences between heterogeneous and homogeneous soil disappeared when soil was sterilized, suggesting that the effects in nonsterilized soils were due to species‐specific soil biota that had responded to soil conditioning.
We conclude that plants produce more biomass when own and foreign soils are patchily distributed than when mixed. We show that this enhanced productivity is due to nutrient uptake being overall most efficient when own and foreign soils are spatially separated. We propose that spatial heterogeneity of negative plant–soil feedback in species diverse plant communities may provide a better explanation of overyielding than assuming that plant–soil feedback effects are diluted.
Lay Summary
Double Porphyrin Cage Compounds Stout, Kathleen; Peters, Theo P. J.; Mabesoone, Mathijs F. J. ...
European journal of organic chemistry,
December 7, 2020, Letnik:
2020, Številka:
45
Journal Article
Recenzirano
Odprti dostop
The synthesis and characterization of double porphyrin cage compounds are described. They consist of two porphyrins that are each attached to a diphenylglycoluril‐based clip molecule via four ...ethyleneoxy spacers, and are linked together by a single alkyl chain using “click”‐chemistry. Following a newly developed multistep synthesis procedure we report three of these double porphyrin cages, linked by spacers of different lengths, i.e. 3, 5, and 11 carbon atoms. The structures of the double porphyrin cages were fully characterized by NMR, which revealed that they consist of mixtures of two diastereoisomers. Their zinc derivatives are capable of forming sandwich‐like complexes with the ditopic ligand 1,4‐diazabicyclo2,2,2octane (dabco).
The synthesis of double porphyrin cage compounds based on glycoluril is described. Through a multistep synthesis, three double cage compounds linked by spacers of variable length are obtained. The binding and conformational properties of their zinc derivatives towards the ditopic ligand dabco have been investigated into detail.
The prudent use of antimicrobials (AMs) should be widened in pig farming to reduce the risk of AM resistance (AMR) in human and veterinary medicine. It is therefore important to understand pig ...farmers' motivators and the barriers to AM usage (AMU) on their farms. The authors investigated pig farmers' self-estimated levels of AMU, their perceived benefits and risks and the need for AMs in a cross-sectional survey in Belgium, France, Germany and Sweden. The authors also compared these perceptions between the four countries and related them to pig farmers' actual AMU. The results showed that farmers who used more AMs also estimated their own usage as higher. Farmers perceived many benefits but relatively few risks of AMU in pig farming. Some significant cross-country differences in farmers' perceptions were found, but they were relatively small. After controlling for country differences and farm differences, only perceived risks had a significant association with AMU. The authors therefore conclude that in order to promote prudent AMU, it seems most promising to focus on the structural differences in pig farming and veterinary medicine (e.g. legislation, role of the veterinarian) among countries. In addition, interventions which aim at reducing AMU should increase farmers' awareness of the risks of extensive AMU.
Measurements show correct operation with supply voltages in the range from 1.4 V down to 0.85 V, a reference voltage of 405 mV plusmn 7.5 mV ( sigma = 6 mV chip-to-chip statistical spread), and a ...reference voltage shift of only plusmn1.5 mV (around 0.8%) under irradiation up to 44 Mrad (Si).
On the geometrical design of integrated Micromegas detectors Blanco Carballo, V.M.; Salm, C.; Smits, S.M. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
06/2007, Letnik:
576, Številka:
1
Journal Article
Recenzirano
Odprti dostop
This paper presents the operational characteristics of several integrated Micromegas detectors. These detectors called InGrids are made by means of micro-electronic fabrication techniques. These ...techniques allow a large variety of detector geometry to be made and studied. Gain, gain homogeneity and energy resolution were measured for various amplification gap sizes, hole pitches and hole diameters in Argon/Isobutane. Gain measurements as a function of gap thickness are compared to the Rose and Korff formula and a model of the detector gain. Our model uses electric field maps and MAGBOLTZ calculated amplification coefficients.
Recent developments in soft matter science provide options to add mobility and motility to polymer films and surfaces. Restrictively, the dynamics in these materials are modulated by a pulsated ...trigger and the route to autonomous dynamics is still a most intriguing challenge. Here, is the design of a self‐sustaining oscillating surface is reported that is fueled by a continuous AC electric field without an intermittent on–off switch. The underlying principle is based on the polarity inversion over the poly(dimethyl siloxane) layer with a 10 nm thick silicon oxide top layer by an integrated tri‐electrode structure connected to an alternating power source. In absence of the electric signal, the coating surface is flat. By applying an AC field, the surface corrugates into a sinusoidal morphology and starts oscillating to develop a continuous standing wave. Typically, the oscillation frequency is 0–5 Hz and the modulation depth is 150 nm. The topographical dynamics are analyzed in terms of viscoelastic materials properties and actuation kinetics and are supported by finite element calculations.
Self‐sustaining oscillating waves in a coating surface are created by maximizing the Maxwell effect via a push‐pull mechanism based on sustained volume conservation within a polysiloxane polymer network. A finite element model that predicts the profile and the oscillation frequency of the wave is developed. The results are relevant for fields varying from (soft) robotic manipulation to haptics.
Antimicrobial use in pig farming is influenced by a range of risk factors, including herd characteristics, biosecurity level, farm performance, occurrence of clinical signs and vaccination scheme, as ...well as farmers’ attitudes and habits towards antimicrobial use. So far, the effect of these risk factors has been explored separately. Using an innovative method called multiblock partial least-squares regression, this study aimed to investigate, in a sample of 207 farrow-to-finish farms from Belgium, France, Germany and Sweden, the relative importance of the six above mentioned categories or ‘blocks’ of risk factors for antimicrobial use in pig production. Four country separate models were developed; they showed that all six blocks provided useful contribution to explaining antimicrobial use in at least one country. The occurrence of clinical signs, especially of respiratory and nervous diseases in fatteners, was one of the largest contributing blocks in all four countries, whereas the effect of the other blocks differed between countries. In terms of risk management, it suggests that a holistic and country-specific mitigation strategy is likely to be more effective. However, further research is needed to validate our findings in larger and more representative samples, as well as in other countries.
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