Spread Of Solutions Research Articles

A bi-objective optimization for finance-based and resource-constrained robust project scheduling

Numerous finance-based projects encounter disturbances from a variety of uncertain factors during their execution, under which both the original baseline schedule and financing alternative become infeasible. However, many previous studies on the finance-based project scheduling problem (FBSP) neglected a potential feature of stochastic activity durations. In this paper, we address the issue of generating a robust project schedule that not only satisfies financing credit and renewable resource limits, but also tackles disruptions due to activity uncertainty. A bi-objective model for finance-based and resource-constrained robust project scheduling problem (FBRCRPSP) is constructed, where the trade-off between profit and robustness is considered. Based on the transformed integer programming model, an exact procedure of ε- constraints is proposed to obtain Pareto-optimal solutions for small-sized instances. For large-scale projects, a non-dominated sorting genetic algorithm with local search (NSGA-II-LS) that deeply explores the neighboring solution space is developed, in which a generic procedure with two new recursion policies is proposed to determine the robustness of schedules. Benchmarking is conducted to evaluate the efficiency of the algorithms via some performance criteria. The results show that all developed approaches have good performance in small-sized instances, and the NSGA-II-LS outperforms the non-dominated sorting genetic algorithm without local search (NSGA-II) in terms of the spread, convergence, and diversity of Pareto-optimal solutions significantly. In addition, some managerial insights are summarized to enlighten project managers.

A Primer on Seq2Seq Models for Generative Chatbots

The recent spread of Deep Learning-based solutions for Artificial Intelligence and the development of Large Language Models has pushed forwards significantly the Natural Language Processing area. The approach has quickly evolved in the last ten years, deeply affecting NLP, from low-level text pre-processing tasks –such as tokenisation or POS tagging– to high-level, complex NLP applications like machine translation and chatbots. This article examines recent trends in the development of open-domain data-driven generative chatbots, focusing on the Seq2Seq architectures. Such architectures are compatible with multiple learning approaches, ranging from supervised to reinforcement and, in the last years, allowed to realise very engaging open-domain chatbots. Not only do these architectures allow to directly output the next turn in a conversation but, to some extent, they also allow to control the style or content of the response. To offer a complete view on the subject, we examine possible architecture implementations as well as training and evaluation approaches. Additionally, we provide information about the openly available corpora to train and evaluate such models and about the current and past chatbot competitions. Finally, we present some insights on possible future directions, given the current research status.

Dynamic Fluid Connectivity Controls Solute Dispersion in Multiphase Porous Media Flow

AbstractSolute transport in multiphase flow through porous media plays a central role in many natural systems and geoengineering applications. The interplay between fluid flow and capillary forces leads to transient flow dynamics and phase distributions. However, it is not known how such dynamic flow affects the dispersion of transported species. Here, we use highly resolved numerical simulations of immiscible two‐phase flow to investigate dispersion in multiphase flows. We show that repeated activation and deactivation of different flow pathways under the effect of capillary forces accelerates the spreading of solutes compared to single phase flow. We establish the transport laws under dynamic multiphase flows by linking the dispersion coefficient to the Bond number, the ratio of the force driving the flow and the surface tension. Our results determine the controlling factors for solute dispersion in porous media, opening a range of applications for understanding and controlling transport in porous geological systems.

Distributed dominance graph-based neural multi-objective evolutionary strategy for sponsored search real-time bidding

In industrial online advertising, real-time bidding optimization has brought substantial profits. Existing methods usually set fixed bids for advertisers which causes collusion among advertisers, resulting in unsatisfactory performance. In this work, by considering both advertisers’ and the platform’s objectives, we formulate the problem as a multiobjective optimization problem and propose a neural evolutionary strategy-based framework to learn the optimal bidding strategy. Since the objectives of advertisers and the platform are conflicting to some extent, it is crucial to properly balance them. A straightforward idea is to simply add up the objectives. However, this could limit the diversity of solutions, leading to suboptimal performance. To this end, we innovatively develop a distributed dominance graph-based neural Pareto multiobjective evolutionary strategy, which can learn a better spread of solutions to improve the model performance. In addition, it can distribute the total computational cost among thousands of workers, improving computational efficiency. We conduct a suite of offline experiments as well as the standard online A/B test on the Taobao platform. The experimental results indicate that our method can significantly improve the profits of both advertisers and the platform.

Towards Formulation of Highly Acidic Active Ingredients: Development of Clinically Effective Concentrated Trichloroacetic Acid Gel for Wart Management.

Common warts are benign skin lesions caused by the human papillomavirus. Although they are usually not harmful, they can cause pain, depending on their location. While many modalities are available for treatment of warts, none is a gold standard, and many are not affordable and/or have suboptimal outcomes. Trichloroacetic acid (TCA) is a chemical tissue-destroying agent used as a highly concentrated solution for wart management. While available and efficient, it is difficult to handle as the solution spreads to tissue surrounding the wart causing pain and burning. Hence, we developed a new polymer-based gel of high TCA content (100% w/v). Gels were formed successfully as hydroxyethyl cellulose (HEC) and chitosan were used to impart viscosity and bioadhesion. Formulae of different concentrations were tested for their physical properties, and the optimal formulation was selected for clinical evaluation. A combination of 3% HEC and 2% chitosan provided optimal viscosity and limited water content and have acceptable stability. The efficacy and safety of the biweekly application of TCA gel were evaluated in 30 patients. The clinical study revealed gel's efficacy and tolerability; half of the patients showed a complete cure, and 90% showed improvement within 6weeks. Only 10-12% of the patients reported side effects. In summary, transforming TCA solution into a gel enabled its application and handling in a practical manner by physicians and patients alike, while maintaining its efficacy as a tissue-destroying agent. Moreover, it is economic and easy to apply, rendering it a promising formulation for similar conditions requiring controlled tissue ablation.

Examples for the application of rule-based algorithms in the simulation modeling of the physical separation of automated guided vehicles

Nowadays, in parallel with the rapid spread of modern automation and digitalization solutions, different autonomous systems are playing an increasingly important role in the field of industry and logistics, a classic example of which is the case of automated guided vehicles (AGVs). Although these devices have been in use for a long time in the aforementioned areas, at the same time, in parallel with the progress of automation in the recent period, in many cases they can be seen more and more as autonomous mobile robots (AMRs), which perform the tasks assigned to them with a high degree of independence. At the same time, issues such as the problem of preventing collisions between individual freely moving vehicles in industrial environments naturally come to the fore. The purpose of this publication is to provide an example for the structure of some simpler rule-based algorithms in response to the former question, which may be relevant in terms of avoiding some potential collision situations of lower complexity. The operation of the algorithms was represented using the Siemens Tecnomatix Plant Simulation discrete event simulation software.

Exploring the role of different data types and timescales in the quality of marine biogeochemical model calibration

Abstract. Global biogeochemical ocean models help to investigate the present and potential future state of the ocean, its productivity and cascading effects on higher trophic levels such as fish. They are often subjectively tuned against data sets of inorganic tracers and surface chlorophyll and only very rarely against organic components such as particulate organic carbon or zooplankton. The resulting uncertainty in biogeochemical model parameters (and parameterisations) associated with these components can explain some of the large spread of global model solutions with regard to the cycling of organic matter and its impacts on biogeochemical tracer distributions, such as oxygen minimum zones (OMZs). A second source of uncertainty arises from differences in the model spin-up length as, so far, there seems to be no agreement on the required simulation time that should elapse before a global model is assessed against observations. We investigated these two sources of uncertainty by optimising a global biogeochemical ocean model against the root-mean-squared error (RMSE) of six different combinations of data sets and different spin-up times. Besides nutrients and oxygen, the observational data sets also included phyto- and zooplankton, as well as dissolved and particulate organic phosphorus (DOP and POP, respectively). We further analysed the optimised model performance with regard to global biogeochemical fluxes, oxygen inventory and OMZ volume. Following the optimisation procedure, we evaluated the RMSE for all tracers located in the upper 100 m (except for POP, for which we considered the entire vertical domain), regardless of their consideration during optimisation. For the different optimal model solutions, we find a narrow range of the RMSE, between 14 % of the average RMSE after 10 years and 24 % after 3000 years of simulation. Global biogeochemical fluxes, global oxygen bias and OMZ volume showed a much stronger divergence among the models and over time than RMSE, indicating that even models that are similar with regard to local surface tracer concentrations can perform very differently when assessed against the global diagnostics for oxygen. Considering organic tracers in the optimisation had a strong impact on the particle flux exponent (Martin b) and may reduce much of the uncertainty in this parameter and the resulting deep particle flux. Independent of the optimisation setup, the OMZ volume showed a particularly sensitive response with strong trends over time, even after 3000 years of simulation time (despite the constant physical forcing); a high sensitivity to simulation time; and the highest sensitivity to model parameters arising from the tuning strategy setup (variation of almost 80 % of the ensemble mean). In conclusion, calibration against observations of organic tracers can help to improve global biogeochemical models even after short spin-up times; here especially, observations of deep particle flux could provide a powerful constraint. However, a large uncertainty remains with regard to global OMZ volume and its evolution over time, which can show very dynamic behaviour during the model spin-up, which renders temporal extrapolation to a final equilibrium state difficult if not impossible. Given that the real ocean shows variations on many timescales, the assumption of observations representing a steady-state ocean may require some reconsideration.

Spreading and Extinction of Solutions to the Logarithmic Diffusion Equation with a Logistic Reaction

We investigate the behavior of positive solutions of \begin{equation*} \left\{ \ \begin {aligned} &\partial_t u = \partial_x^2 (\log u) + u(1-u), \qquad \quad x\in \mathbb {R}, \\ & \lim_{x\to -\infty } \partial_x (\log u) = \alpha, \quad \lim_{x\to \infty } \partial_x (\log u) = - \beta, \end {aligned} \right. \nonumber \end{equation*} where are given nonnegative constants. This equation has a traveling pulse solution if and only if , and any solution vanishes in a finite time when . For the case of , we successfully classified the behavior of solutions into three categories: spreading, boundedness of total mass, and vanishing. Then, we describe in detail the asymptotic behavior of solutions in each category. First, the transition layer of the spreading solution propagates with the speed of a traveling front. Second, the mass-bounded solution converges to a traveling pulse solution. Third, a rescaled profile of vanishing solution converges to some traveling pulse in an asymptotically self-similar manner. In addition, the heteroclinic orbits that connect the traveling pulse to are constructed.

Surfactants Improving the Wetting Behavior and Adhesion Mechanism of Pesticide Dilution Droplets on Jujube Leaf Surfaces.

Fruit tree leaves have different chemical compositions and diverse wax layer structures that result in different patterns of wetting and pesticide solution spreading on their surface. Fruit development is a time when pests and diseases occur, during which a large number of pesticides are needed. The wetting and diffusion properties of pesticide droplets on fruit tree leaves were relatively poor. To solve this problem, the wetting characteristics of leaf surfaces with different surfactants were studied. The contact angle, surface tension, adhesive tension, adhesion work, and solid-liquid interfacial tension of five surfactant solution droplets on jujube leaf surfaces during fruit growth were studied by the sessile drop method. C12E5 and Triton X-100 have the best wetting effects. Two surfactants were added to a 3% beta-cyfluthrin emulsion in water, and field efficacy tests were carried out on peach fruit moths in a jujube orchard at different dilutions. The control effect is as high as 90%. During the initial stage when the concentration is low, due to the surface roughness of the leaves, the surfactant molecules adsorbed at the gas-liquid and solid-liquid interfaces reach an equilibrium, and the contact angle on the leaf surface changes slightly. With increasing surfactant concentration, the pinning effect in the spatial structure on the leaf surface is overcome by liquid droplets, thereby significantly decreasing the contact angle. When the concentration is further increased, the surfactant molecules form a saturated adsorption layer on the leaf surface. Due to the existence of a precursor water film in the droplets, surfactant molecules on the interface continuously move to the water film on the surface of jujube tree leaves, thus causing interactions between the droplets and the leaves. The conclusion of this study provides theoretical guidance for the wettability and adhesion of pesticides on jujube leaves, so as to achieve the purpose of reducing pesticide use and improving pesticide efficacy.

The digital world and atypical work: Perceptions and difficulties of teleworking in Hungary and Romania

IT solutions have been transforming the world of work, albeit with varying intensity, for decades. They affect, among other things, the organisation of work, work structures, employment patterns and working time. Solutions such as artificial intelligence (AI), business intelligence (BI), robotic process automation (RPA), workflow, process mining, etc. are now a daily reality in the corporate sector, be it physical or mental work. However, the spread of digital solutions across organisations, spaces and sectors is uneven. Can the impact of this uneven spread be observed in employment, especially in atypical forms of employment? In our questionnaire research, we seek to establish how employees with tertiary education in two pairs of sectors (Hungarian and Romanian non-profit sectors and Hungarian non-profit and for-profit sectors) in two countries perceive some demographic characteristics of teleworking. In our research, we analysed the responses of Hungarian and Romanian working-age citizens with tertiary education who had been working in telework for at least one year at the time of completing the questionnaire. In addition to the deterioration of work relationships and the lack of personal contacts already shown by many studies, it is observed that the work-life balance is upset for single people and those without children, while the number of children does not influence opinions on teleworking. The differences observed and presented in the study are typically not gender-specific but largely based on globalised perspectives.

Performance of Six Metaheuristic Algorithms for Multi-Objective Optimization of Nonlinear Inelastic Steel Trusses

This paper presents a multi-objective optimization of steel trusses using direct analysis. The total weight and the inter-story drift or displacements of the structure were two conflict objectives, while the constraints relating to strength and serviceability load combinations were evaluated using nonlinear inelastic and nonlinear elastic analyses, respectively. Six common metaheuristic algorithms such as nondominated sorting genetic algorithm-II (NSGA-II), NSGA-III, generalized differential evolution (GDE3), PSO-based MOO using crowding, mutation, and ε-dominance (OMOPSO), improving the strength Pareto evolutionary algorithm (SPEA2), and multi-objective evolutionary algorithm based on decomposition (MOEA/D) were applied to solve the developed MOO problem. Four truss structures were studied including a planar 10-bar truss, a spatial 72-bar truss, a planar 47-bar powerline truss, and a planar 113-bar truss bridge. The numerical results showed a nonlinear relationship and inverse proportion between the two objectives. Furthermore, all six algorithms were efficient at finding feasible optimal solutions. No algorithm outperformed the others, but NSGA-II and MOEA/D seemed to be better at both searching Pareto and anchor points. MOEA/D was also more stable and yields a better solution spread. OMOPSO was also good at solution spread, but its stability was worse than MOEA/D. NSGA-III was less efficient at finding anchor points, although it can effectively search for Pareto points.

The history of UK weather forecasting: the changing role of the central guidance forecaster. Part 5: rapid advances in the forecasting process – the late twentieth century

The early 1980s ushered in rapid advances in forecasting skill with the introduction of the Met Office 15-level model in 1982, including much improved forecasting of cyclogenesis. Nevertheless, there remained many opportunities for forecasters to add value to computer output, for example by using an increasing range of satellite imagery. However, failure to predict the impacts from the Great Storm of October 1987 forced a major rethink of the severe weather warnings strategy. Outputs from other forecasting centres became available, in particular, ensembles from European Centre for Medium-Range Weather Forecasts. New operational working procedures evolved to maximise benefits derived from this ever-increasing volume of information. Figure S1. (a) Infra-red image and global model 6-h forecasts of sea-level pressure valid 1200 utc 27 November 2002 over the eastern Pacific Ocean. Bold red arrow shows an observation of 980hPa which was 12hPa below model expectations. (b) Model forecast and observations for same time on the Met Office ‘intervention’ display screen. Observations differing from the model by >3hPa are shown in red (also circled in red). The wind plotted in cyan has been corrected from an assumed erroneous value. (c) As (b) but with cyan plots including additional ‘bogus’ observations created to attempt to replicate the correct position of the low, as inferred from imagery and observations shown in (b). (d) Imagery and observations for 1200 utc 27 November 2002 with original model 6-h forecast (red) and new analysis following intervention (cyan). (e) As (d) but for 1800 utc 27 November 2002 showing that the benefit of intervention has been retained in the new forecast, with the new forecast (cyan) placing the more vigorous depression centre correctly in the dry slot. Crown copyright. Figure S2. (a) Individual solutions (postage stamps) from the ECMWF ensemble for 1200 utc 17 December 1997 from a forecast initiated at 1200 utc 10 December 1997. (b) Plume of 850hPa temperatures at Herstmonceux (Sussex) up to 10 days ahead from the same ensemble forecast showing the spread of solutions, which typically increases with time. The bold dashed line represents the higher resolution deterministic model solution and the bold solid line the unperturbed (control) run at the lower resolution of the ensemble members. Contours represent probability for 1.0 degC intervals, with increasing density of stippling for successive intervals; 0.5–10%, 10–30%, 30–50% and 50–100%. The deterministic run is an outlier, falling outside the range of the ensemble around days 7 to 8. (c) is the ‘central cluster’, effectively a mean of the most common solutions in the ensemble at 1200 utc 17 December 1997, (d) and (e) are ensemble members representative of minority solutions verifying at the same time. Data S1 Supporting Information Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

Langmuir and Langmuir-Blodgett Films of Gold and Silver Nanoparticles.

Recently the focus of the Langmuir-Blodgett technique as a method of choice to transfer monolayers from the air/water interface onto solid substrates in a controllable fashion has been shifting toward purely hydrophobic gold and silver nanoparticles. The fundamental interactions between particles that become relevant in the absence of polar groups range from dispersive attractions from the metal cores and repulsions between ligand shells to weaker entropic factors. The layer evolution is explored, starting with interfacial self-assembly upon solution spreading and domain and circular island formation, which subsequently merge into a complete monolayer and finally form multilayers or macroscopic wrinkles. Moreover, structural properties such as the core:ligand size ratio are investigated in the context of dispersive forces, whereby the nanoparticles with small cores and long ligands tend not to aggregate sufficiently to produce continuous films, those with large cores and short ligands were found to aggregate irreversibly, and those in between the two extremes were concluded to be able to form highly organized crystalline films. Similarly, the characteristics of the spreading solution such as the concentration and the solvent type crucially influence the film crystallinity, with the deciding factor being the degree of affinity between the capping ligand and the solvent used for spreading. Finally, the most common strategies employed to enhance the mechanical stability of the metal nanoparticle films along with the recent attempts to functionalize the particles in attempts to improve their applicability in the industry are summarized and evaluated in relation to their future prospects. One of the objectives of this feature article is to elucidate the differences between hydrophobic metal nanoparticles and typical amphiphilic molecules that the majority of the literature in the field describes and to familiarize the reader with the knowledge required to design Langmuir-Blodgett nanoparticle systems as well as the strategies to improve existing ones.

Evaluating Patterns of Injectate Spread After Rectus Sheath Block: A Cadaveric Dissection Study.

This cadaveric dye study assesses the effect of volume and number of injections on the spread of solution after ultrasound-guided rectus sheath injections. In addition, this study evaluates the impact of the arcuate line on solution spread. Ultrasound-guided rectus sheath injections were performed on seven cadavers on both sides of the abdomen, for a total of 14 injections. Three cadavers received one injection of 30 mLof a solution consisting of bupivacaine and methylene blue at the level of the umbilicus. Four cadavers received two injections of 15 mLof the same solution, one midway between the xiphoid process and umbilicus and one midway between the umbilicus and pubis. Six cadavers were successfully dissected and analyzed for a total of 12 injections, while one cadaver was excluded due to poor tissue quality that was inadequate for dissection and analysis. There was a significant spread of solution with all injections caudally to the pubis without limitation by the arcuate line. However, a single 30 mLinjection showed inconsistent spread to the subcostal margin in four of six injections, including in a cadaver with an ostomy. A double injection of 15 mLshowed consistent spread from xiphoid to pubis in five of six injections, except in a cadaver with a hernia. Injections deep to the rectus abdominis muscle, using the same technique as an ultrasound-guided rectus sheath block, achieve spread along a large and continuous fascial plane without limitation by the arcuate line and may provide coverage of the entire anterior abdomen. A large volume is necessary for complete coverage and spread is improved with multiple injections. We suggest that two injections with a total volume of at least 30 mLper side may be needed to achieve adequate coverage in the absence of preexisting abdominal abnormalities.

Effect of the Blade-Coating Conditions on the Electrical and Optical Properties of Transparent Ag Nanowire Electrodes.

Optimizing the coating conditions for a doctor blading system is important when seeking to improve the performance of Ag nanowire electrodes. In this study, the effect of the blading height and speed on the optical and electrical properties of Ag nanowire electrodes was investigated. Ag nanowires were first spread on a PET substrate using a doctor blade with differing heights at a fixed blading speed. An increase in the blading height resulted in the degradation of the optical transmittance and stronger haze due to the higher probability of Ag nanowire agglomeration arising from the greater wet thickness. When the blading speed was varied, the optical transmittance and haze were unaffected up until 20 mm/s, followed by minor degradation of the optical properties at blading speeds over 25 mm/s. The higher speeds hindered the spread of the Ag nanowire solution, which also increased the probability of Ag nanowire agglomeration. However, this degradation was less serious compared to that observed with a change in the blading height. Therefore, optimizing the blading height was confirmed to be the priority for the production of high-performance transparent Ag nanowire electrodes. Our study thus provides practical guidance for the fabrication of Ag nanowire electrodes using doctor blading systems.

Streamlines based methodology for determining the acidity balance of solutions of technological blocks developed by in-situ leaching

The in-situ leaching is a method of developing low-concentration ore deposits occurring in permeable rocks by pumping a leaching solution into the reservoir through injection wells, which dissolve the mineral in situ and pumping the productive solution to the surface through pumping wells. During development, the deposit is divided into technological blocks; developments of each block could be independent from others. To improve the environmental friendliness of work and prevent the spreading of solutions beyond the boundaries of the block, a balance of solutions is observed, i.e. the volumes of injected leaching and pumped out productive solution should be equal. In this connection, the question arises of calculating flow rates at injection wells in adjacent blocks. Currently, the distribution of flow rates of injection wells in adjacent technological blocks is calculated by averaging the extraction wells interacting with a given well. However, the accuracy of this calculation is quite low, since it does not take into account both the reservoir properties and the distances between wells. In this connection, in this paper, it is proposed to calculate well flow rates based on modeling, based on the fundamental laws using streamlines. Thus, the proposed technique makes it possible to take into account the direction of the flow of the solution and the filtration properties of the rock.

Study on Multi-Factor Optimization and Application for Water Mist of a Wetting Dust Suppressant.

Aiming at the problem of low efficiency of capturing respirable and hydrophobic dust in water mist dust removal technology, a chemical dust suppression method is adopted. Based on the research idea of improving the wetting efficiency of water mist, prolonging the droplet retention time, and improving the contact opportunity with dust, the experiments of dust sedimentation time, solution spreading area, and water loss rate are selected to evaluate the wetting efficiency and anti-evaporation performance of dust suppression water mist. Considering the special double-chain structure of the Gemini surfactant and its high wettability, it is preferred as the main dust suppression component. Based on the indoor experimental data, the optimized formula of the composite wet water mist dust suppressant was obtained by CCD-RSM(central composite design-response surface methodology). The comparison of indoor experimental data shows that the sedimentation time of the dust sample in the water mist dust suppressant is 5.0 times faster than that of pure water, the spreading area of the dust suppressant solution is 1.8 times that of pure water, and the water loss rate of the dust sample treated by the dust suppressant is 70% that of pure water. The field investigation results show that compared with pure water mist, the dust removal rates of the Gemini wetting dust suppressant for respirable dust and total dust are 90.3 and 71.1%, respectively, which are 10.5 and 22.5% higher than that of pure water mist. It can be proved that improving the wetting efficiency and anti-evaporation performance of spray mist will increase the dust removal efficiency.

Processing Additives for Solution‐Deposited Films of Zinc Phthalocyanine

AbstractZinc phthalocyanine (ZnPc) receives attention from the industry of optoelectronic materials; so, a much‐needed algorithm for uniformly crystalline ZnPc films unimpaired by grain boundaries is under development in the laboratory. Such films are obtainable from solutions based on the binary cyclopentanone–3‐dimethylamino‐1‐propanol system where ketone is a solvent and aminoalcohol acts as a multifunctional processing additive. This work reports on auxiliary additives intended to fully control the film formation: 3‐bromopyridine and two ZnPc‐based amphiphiles, including a novel one‐tailed amphiphile mimicking classic surfactants. The former component, removable from deposited films upon mild annealing, amends the vertical development of the three‐dimensional (3D) phase, while the latter ones normalize important physicochemical processes, such as solution spreading and solvent evaporation. Variously shaped ZnPc particles modified with the mentioned additives are prepared by drop‐casting and examined by atomic force microscopy with the emphasis on phase‐contrast imaging. Applied aspects for the said additives are outlined.

Comparison of Lugol’s solution and Fe3O4 nanoparticles as contrast agents for tumor spheroid imaging using microcomputed tomography

Abstract Background Lugol’s solution is well known for its unique contrasting properties to biological samples in in microcomputed tomography imaging. On the other hand, iron oxide nanoparticles (IONPs), which have much lower attenuation capabilities to X-ray radiation show decent cell penetration and accumulation properties, are increasingly being used as quantitative contrast agents in biology and medicine. In our research, they were used to stain 3D cell structures called spheroids. Aim In this study, the micro computed tomography (µCT) technique was used to visualize and compare the uptake and accumulation of two contrast agents, Lugol’s solution and iron (II, III ) oxid e nanoparticles (IONPs) in the in vitro human spheroid tumour model. Methods The metastatic human melanoma cell line WM266-4 was cultured, first under standard 2D conditions, and after reaching 90% confluence cells was seeded in a low adhesive plate, which allows spheroid formation. On the 7th day of growth, the spheroids were transferred to the tubes and stained with IONPs or Lugol’s solution and subjected to µCT imaging. Results Our research allows visualization of the regions of absorption at the level of single cells, with relatively short incubation times - 24h - for Lugol’s solution. IONPs proved to be useful only in high concentrations (1 mg/ml) and long incubation times (96h). Conclusions When comparing the reconstructed visualizations of the distribution of these stating agents, it is worth noting that Lugol’s solution spreads evenly throughout the spheroids, whereas IONPs (regardless of their size 5 and 30 nm) accumulate only in the outer layer of the spheroid structure.

Liquid-liquid interface induced high-flux PEBA pervaporation membrane for ethanol recovery

Bioethanol has achieved increasing attention in alleviating energy crisis and environmental issues. Pervaporation could be a promising technology to separate ethanol from fermentation. Traditionally, the liquid polymetric solution was compounded on solid porous supports to form composite membranes. Through this liquid-solid interface, it is challenging to precisely control the structure and achieve high pervaporation performance. In this work, we aimed to overcome some of these limitations and designed a polyether block amide (PEBA) pervaporation membrane by dropping the membrane solution on a water surface. While the membrane solution spreading, solvent-water exchange and solvent evaporation occurred. Thereafter the polymer precipitation was induced in the solvent-water interface. The defect-free and uniform selective layer with a thickness of 3.9 μm was achieved by optimizing the ratio of solvent, and the temperature of the water. The PEBA layer was deposited onto porous polytetrafluoroethylene (PTFE) substrate for recovering ethanol from water by pervaporation. The membrane represented a total flux and separation factor of 3.9 kg m−2 h−1 and 4.9, which was maintained stable for 100 h. The interface-induced membrane demonstrated high separation performance and membrane stability.