Passive Absorption Research Articles

Role of ion exchange membranes and capacitive electrodes in membrane capacitive deionization (MCDI) for CO2 capture

Recently we showed that membrane capacitive deionization (MCDI) can be used to capture CO2, but we found that the performance decreases with decreasing current density. In the present study, we investigate the effect of electrodes and ion exchange membranes by performing experiments with two membranes (CO2-MCDI), with one membrane (cation or anion exchange membrane), and without membranes (CO2-CDI). We find that the anion exchange membrane is essential to keep high CO2 absorption efficiencies (Λa=nCO2(g)/ncharge), while the absorption efficiency of the CO2-CDI cell was lower than expected (Λa≈0.5 for CO2-MCDI against Λa≈0.18 for CO2-CDI). Moreover, we theoretically investigate ion adsorption mechanisms in the electrodes by comparing experimental data of a CO2-CDI cell with theoretical results of the classic amphoteric-Donnan model developed for conventional CDI. By comparing the experimental results with the amph-D model, we find that the model overestimates the absorption efficiency in CO2-CDI experiments. To understand this discrepancy, we investigate the effects of other phenomena, i.e., (i) low ion concentration, (ii) passive CO2 absorption, and (iii) the effect of acid-base reactions on the chemical surface charge.

Scalable Top-to-Bottom Design on Low Tortuosity of Anisotropic Carbon Aerogels for Fast and Reusable Passive Capillary Absorption and Separation of Organic Leakages.

Creation of sustainable, cost-effective, and scalable absorbents with ideal absorption properties is a worldwide challenge because many high-performance absorbents are still restricted in laboratory scope due to several critical defects (like complex and eco-unfriendly synthesis process, high cost, and difficulty in large-scale production). Herein, a facile and scalable top-to-bottom design is proposed to create a kind of novel anisotropic carbon aerogels with low tortuosity of stacked laminated structure, derived from the hierarchical cellular channels of balsa wood. By virtue of this unique structure and favorable oleophilicity, fast passive capillary absorption with low flow resistance is achieved (as demonstrated by the theoretical modeling). As a result, the anisotropic carbon aerogels have quite sensitive selectivity to separate organic pollutants from water, broad-spectrum and high absorption capacity for different organic liquids (13 277-31 597 mg g-1), and superior recyclability (98.7% absorption capacity retention after five cycles). Combining these outstanding performances with a cheap preparation strategy as well as good environmental friendliness, this work provides a kind of potential scalable materials for efficient reusable absorption and separation of organic leakages.

Positive impact of vermicompost leachate on salt stress resistance in tomato (Solanum lycopersicum L.) at the seedling stage: a phytohormonal approach

Vermicompost leachate (VCL) produced by earthworms is a valuable biostimulant but its hormonal impact on salt-treated plants remains elusive. Plants of Solanum lycopersicum L. were cultivated in nutrient solution and exposed during 7 days to 125 mM NaCl in the presence or absence of VCL (18 mL.L−1). Mineral nutrition, water and hormonal status were quantified in roots, young and old leaves and analyzed in relation to phytohormone content of VCL. VCL improved plant growth and reduced Na+ accumulation in salt-stressed plants. It delayed senescence in young leaves through a decrease in ethylene synthesis and an increase in proline and anthocyanin contents. VCL contains high amounts of salicylic acid, benzoic acid and aminocyclopropane carboxylic acid (ACC) but low concentrations of jasmonates, cytokinins and proline. VCL did not increase abscisic acid content in salt-stressed plants and did not lead to ACC accumulation while it increased jasmonate accumulation and modified the pattern of cytokinin profile with an increase in dihydrozeatin-types in old leaves and N6-(∆2-isopentenyl)adenine-types in young ones. VCL reduces the impact of salinity on leaf senescence, which is related to its impact on endogenous phytohormones rather than to a passive absorption of exogenous hormonal compounds.

Tropospheric NO2 Monitoring Using the Multi-Axis Differential Optical Absorption Spectroscopy in Urban Area

Spectroscopic methods have played an important role in the study of chemical and physical processes related to the composition of the atmosphere and the differential optical absorption spectroscopy (DOAS) has been one of the most powerful methods to measure a wide range of trace gases. The pollutants are identified by their respective ranges of wavelengths that must be previously known. A Passive Differential Optical Absorption Spectroscopy system that uses the ultraviolet region from 400 to 480 nm of the solar radiation is presented. In this research diurnal variation of NO2 was remotely measured by means of MAX-DOAS system which uses multiple viewing angles to monitor pollutant concentrations in urban area at the city of Rio de Janeiro. The instrument was placed on the roof of a building oriented to the center of the city. Tropospheric NO2 amounts are retrieved from the measured spectra using the DOAS technique. In this paper we give a general description of the procedure and present the results from measurements during four days in winter 2017 associated with the prevailing meteorological aspects. These days were characterized by mostly sunny and dry conditions, no convection, periods of medium clouds and clear sky. The tropospheric NO2 slant column densities values are presented and the results are consistent for all three used elevation angles (5º, 10º, and 15º). The results demonstrate the capability and the potential of the MAX-DOAS technique to derive information on spatial distribution of NO2 in an urban environment.

China's Healthcare Costing in Times of Crisis: Conflicts, Interactions, and Hidden Agendas

This paper presents a longitudinal interpretive case study on the development of healthcare costing in China over the period 2002 to 2015. Adopting a middle‐range theory lens, the study explores dynamic interactions in the use of cost information among societal institutions and organizations. It reports the successful internalization of costing systems in public hospitals in Beijing, which supports the effectiveness of a hybrid steering mechanism combining both transactional and relational features; however, such successful internalization does not indicate the success of steering the lifeworld of institutions and organizations towards change. Notably, hospitals' responses to steering alter over time, from passive absorption to active manipulation, revealing how cost information may underpin hospital beliefs in marketization. At an institutional level, the paper provides empirical evidence for relational steering among societal institutions, where a reaction of ‘rebuttal’ is observed. It offers insights on how accounting can be a powerful tool in legitimizing such rebuttal, while keeping political considerations as hidden agendas. The findings suggest the importance of understanding lifeworld complexity at both societal and organizational levels, and cross‐institutional collaboration in using accounting as a steering mechanism. The findings have important policy implications for public sector reform, both in China and worldwide.

Hydrodynamic Performance of Rectangular Heaving Buoys for an Integrated Floating Breakwater

Recently, the integrated development of wave energy converters and breakwaters has become popular, moving from traditional passive wave absorption to active energy capture. In this study, rectangular heaving buoys are considered as floating breakwater modules to absorb wave energy. A numerical wave tank is established based on Reynolds Averaged Navier-Stokes equation and User-Define-Function in ANSYS-Fluent commercial software. The numerical results show that incident wave conditions and submerged depth have significant effects on the heaving performance and wave energy absorption of a rectangular buoy. Flow structures around the buoy are shown to exhibit flow separations and vortex shedding, which can provide more information on buoy optimization. Power take-off (PTO) reaction forces are assumed to be a linear function of the translation velocities of the buoy. Numerical results demonstrate that a suitable PTO module can improve the wave power absorption by up to 34.2% for certain buoy and wave conditions, which is valuable for further investigations.

Semi-active control of smart porous structure for sound absorption enhancement

For sound absorption of conventional porous materials, its noise-reducing ability in low frequencies is less than that in high frequency bands. A porous layer offers effective sound absorption when the thickness of layer is a quarter wavelength of the sound wave. Increasing the layer thickness is not an effective solution. Adjustment of rear air cavity volume for the porous medium has been used in practical applications to increase low frequency sound absorption. Noise reduction using only passive sound absorption characteristics is a challenge, especially when the operation conditions of noise source changes. In this study, we propose a smart porous material having noise reduction ability in the broad frequency band. We implement semi-active control by applying a magnetic reactive material to a porous medium. The smart foam proposed in this study reduced noise with adjustment of the magnitude and polarity of the magnetic field. Evaluation of its noise reduction performance is performed with the impedance tube method. Experiments are conducted for semi-active noise control of the proposed smart foam. The sound absorption characteristics are controlled efficiently with relatively low electric power consumption. A theoretical model to predict absorption characteristics is proposed using the transfer-matrix method, and its results show good agreement with measured behaviors.

Sound transmission through a thick-walled FGM piezo-laminated cylindrical shell filled with and submerged in compressible fluids

Estimation of sound transmission loss (TL) due to the piezoelectric effects, as an attenuation of acoustic waves, is studied for a thick-walled piezo-composite cylindrical shell excited by an oblique incident plane wave. The cylinder is filled with and submerged in an acoustic media. The three-dimensional (3D) exact theory of elasticity and piezoelasticity are engaged to model the cylindrical shell, while the classical Helmholtz equation governs the propagation of waves through the internal cavity and external surrounding fluid. A state space method, as well as the transfer matrix technique is utilized to describe the deformation and stress in the cylindrical shell. TL is calculated by exact integration over the shell’s outer surface. The validity of the current analytical solutions is cross-checked with various data from the simplified case found in the relevant literature as well as a finite element package known as Comsol Multiphysics. Parameter studies are conducted to investigate the effects of piezoelectric material properties, piezoelectric polarization direction, shell thickness ratio, electrical boundary conditions and functionally graded piezoelectric material (FGPM) on the sound transmission loss due to the piezoelectricity. New results and findings provide guidance of piezoelectric coupled with thick shell design for passive wave absorption.

Hepatic cholesterol accumulation ascribed to the activation of ileum Fxr-Fgf15 pathway inhibiting hepatic Cyp7a1 in high-fat diet-induced obesity rats

AimsHigh-fat diet (HFD)-induced obesity resulting in cholesterol accumulation is one of the common pathogenic factors for lipids metabolic disorders. However, the potential mechanisms about cholesterol accumulation during obesity are still not clearly identified. Bile acids (BAs) as the natural ligands of farnesoid x receptor (Fxr) are demonstrated that can regulate the relevant enzymes and transporters at transcriptional level to determine the cholesterol homeostasis. Here, we explored the underlying mechanisms of hepatic cholesterol accumulation in HFD-induced obesity rats via the BAs-Fxr-enzymes/transporters signaling pathways. Materials and methodsBAs and cholesterol levels as well as mRNA expressions of enzymes, transporters and nuclear receptors involving in cholesterol homeostasis in liver and ileum tissue were evaluated in 4-week HFD-induced obesity rats. Key findingsHFD promoted BAs intestine passive absorption to increase the concentrations of BAs especially the chenodeoxycholic acids (CDCAs) in ileum of HFD-induced obesity rats. The increased CDCAs concentrations activated Fxr-Fgf15 pathway in ileum to result in the mRNA expression of Cyp7a1 in liver down-regulation, which inhibited cholesterol metabolizing into primary BAs to contribute to the cholesterol level increase in liver tissue in HFD-induced obesity rats. SignificanceThe hepatic cholesterol accumulation should be ascribed to the activation of ileum Fxr-Fgf15 pathway by the increased BAs passive absorption into ileal enterocytes under the condition of rats fed with HFD, which inhibited hepatic Cyp7a1 gene transcription to reduce metabolic elimination of cholesterol. Moreover, these findings are expected to provide a cue for the treatment of cholesterol metabolism disorders in obesity patient.

Enteric hyperoxaluria: role of microbiota and antibiotics.

Enteric hyperoxaluria is commonly observed in malabsorptive conditions including Roux en Y gastric bypass (RYGB) and inflammatory bowel diseases (IBD). Its incidence is increasing secondary to an increased prevalence of both disorders. In this review, we summarize the evidence linking the gut microbiota to the risk of enteric hyperoxaluria. In enteric hyperoxaluria, fat malabsorption leads to increased binding of calcium to free fatty acids resulting in more soluble oxalate in the intestinal lumen. Bile acids and free fatty acids in the lumen also cause increased gut permeability allowing more passive absorption of oxalate. In recent years, there is more interest in the role of the gut microbiota in modulating urinary oxalate excretion in enteric hyperoxaluria, stemming from our knowledge that microbiota in the intestines can degrade oxalate. Oxalobacter formigenes reduced urinary oxalate in animal models of RYGB. The contribution of other oxalate-degrading organisms and the microbiota community to the pathophysiology of enteric hyperoxaluria are also currently under investigation. Gut microbiota might play a role in modulating the risk of enteric hyperoxaluria through oxalate degradation and bile acid metabolism. O. formigenes is a promising therapeutic target in this population; however, further studies in humans are needed to test its effectiveness.

Sono‐Immunotherapeutic Nanocapturer to Combat Multidrug‐Resistant Bacterial Infections

Antibiotic-free methods hold particular promise for preventing and controlling multidrug-resistant (MDR) bacterial infection via eradiation of bacteria and their pathogenic virulence. A facile and bioinspired strategy is presented for bridging antibacterial sonodynamic therapy and antivirulence immunotherapy. As a proof-of-concept, an antibody which neutralizes alpha-toxin of methicillin-resistant Staphylococcus aureus (MRSA) is genetically engineered on to the surface of cell membrane nanovesicles, which then undergo sonosensitizer encapsulation. Compared with conventional passive virulence absorption using natural red blood membrane, the highly active antibody-toxin interaction enables the nanovesicles to capture virulence more potently in vitro. Upon ultrasound activation, the sonosensitizers efficiently generate reactive oxygen species to kill bacteria and accelerate the virulence clearance. In vivo optical imaging shows that the antibody-piloted nanocapturer can successfully locate MRSA infection and accurately distinguish the foci from sterile inflammation. In situ magnetic resonance imaging and oxyhemoglobin saturation detection visualize the treatment progression, revealing a complete sono-immunotherapeutic eradication of MRSA myositis in mice. The first combination of antibacterial sonodynamic therapy and antivirulence immunotherapy, which promises a new way for antibiotic-free nanotheranostics to robustly combat MDR bacterial infections, is presented.

Passive vibration control in a civil structure: Experimental results

The problem of vibrations in civil structures is common; nevertheless, its negative effects can be significantly reduced using structural control methods with intention of maintaining structural welfare as much as possible. This work deals with the study of structural vibration control in a model of a civil-like structure, which consists of three-level building with a tuned mass damper implemented as a passive vibration absorber, mounted on the top of the structure, to attenuate the harmonic vibrations provided by an electromagnetic actuator connected at the base of the primary system. The action of the tuned mass damper is evaluated from an energy approach. The dissipation of energy in the overall system is conducted in an experimental way, where the passive control technique is designed to minimize the undesirable forced dynamic response of the main structure via the tuned mass damper. Experimental results are provided to show the effective performance of the proposed passive vibration absorption scheme to suppress resonant frequency harmonic excitations disturbing the primary system, evaluating the performance energy and contribution of the dissipative device for the energy release in the overall system.

The energy distribution of a train impact process based on the active–passive energy-absorption method

Abstract This paper examines the energy-absorption characteristics of trains for active–passive safety protection. A one-dimensional collision-simulation model of traditional subway vehicles and active–passive safety vehicles was developed based on the multibody dynamics theory using MATLAB simulation software. The effectiveness of the simulation model was verified by scaled-collision tests. Then, the energy-absorption characteristics of traditional trains and the active–passive safety trains under different marshalling conditions were studied. The results showed that as the number of marshalling vehicles increased from 5 to 8, the energy absorption of interface 1 for the active–passive safety trains during the collision was 681 kJ, 775 kJ, 840 kJ and 901 kJ, and the physical compression of the interface of the head car of the active–passive safety trains was 619 mm, 704 mm, 764 mm and 816 mm, which was far below the maximum value of 1773 mm. The head car of the active–passive safety subway vehicles therefore had sufficient energy-absorption capacity. Finally, to find the maximum safe impact velocity of the active–passive safety trains, the energy distribution of the active–passive safety subway vehicles with 8-car marshalling at different impact velocities was studied. It was found that the safe impact velocity of an active–passive safety subway vehicle conforming to the requirements of the EN15227 collision standard reached 32 km/h, far exceeding the safe impact velocity of 25 km/h allowed by traditional trains, and representing an increase in the safe impact velocity of 28%. The total collision-energy absorption of the interface of the head car of the active–passive trains was 89.1% higher than that of the traditional trains at the safe impact velocity. The active–passive energy absorption method was therefore effective at improving the crashworthiness of the subway trains.

A Full-Solid-State Humidity Pump for Localized Humidity Control

Summary Humidity management is essential and widely needed in various fields. Traditional moisture removal technologies are mostly based on cooling condensation or desiccant dehumidification. These methods come with inherent defects of energy efficiency and are bulky and complex for small-space humidity-control applications. Here, we demonstrate a full-solid-state humidity pump using the advantages of commercial thermoelectric coolers and silica gel materials. Silica gel is coated on the surface of heat sinks to minimize contact thermal resistance between the material and heat source while maintaining enough heat and mass transfer area between the desiccant and the air. The humidity pump device exhibits 0.61 g W−1 h−1 humidity transfer efficiency, corresponding to a humidity transfer rate of 28.38 g h−1. The proposed device neither uses refrigerant nor introduces liquid water. It opens up the possibility of use in localized humidity control applications with higher efficiency and a wider ambient temperature range than traditional technologies.

Embedding and assessing project based statistics

Traditional approaches to learning and teaching in statistics often involves the passive absorption of information through lectures, a focus on mathematical theory and assessments which test mastery of procedures. This often results in students struggling to apply their statistics knowledge in practical and authentic contexts particularly within final year projects and in the workplace. For some time, statistics educational literature has recommended shifting the focus of teaching and assessment from theory to statistical problem solving, application based statistics using real-life scenarios, and effective communication of statistics. This research has led to the production of guidelines for statistics educators from the American Statistical Association.This paper discusses how educational literature and guidelines have been used to implement changes in the teaching of a first year probability and statistics module for mathematics undergraduates at Sheffield Hallam University. Changing to project based learning with a focus on active learning, effective decision making and communication enabled students to successfully undertake an open group project by the end of their first year. In addition, attendance, engagement and understanding were noticeably improved. The rationale, challenges and benefits to changing the focus of the course and also the teaching style are discussed.

Can the inerter be a successful shock-absorber? The case of a ball-screw inerter with a variable thread lead

This paper investigates an application of a ball-screw inerter for mitigation of impact loadings. The problem of impact absorption is to provide a minimum reaction force that optimally decelerates and eventually stops an impacting object within the available absorber stroke. It significantly differs from vibration mitigation problems which are typical application of inerters. The paper demonstrates that the optimum absorption can be achieved by fully passive means. For known values of the object mass and inerter parameters, the obtained solution is independent of the impact velocity. The optimum passive absorption is achieved by employing a variable thread lead. As a result, two force components emerge, the typical inertance-related force and a damping-like term, and sum up to provide the optimum constant deceleration force. This result is relatively unique: conventional absorbers do not provide a constant force even with complex active control systems. Finally, an optimization problem is formulated to reduce the influence of process uncertainties (range of possible mass values, unknown friction). The results are verified and analyzed in a numerical example.

Towards a new philosophy of history. European Vichianism and Neapolitan Hegelianism (1804–48)

ABSTRACTThis article examines how Hegel’s reception among nineteenth-century Neapolitan authors went hand-in-hand with a renewed interest in Giambattista Vico’s philosophy of history. It considers the mechanisms of circulation and reception that shaped responses to Hegelianism within the broader context of European debates on La Scienza Nuova. These developments largely directed Neapolitans’ understanding of Hegel’s ideas and encouraged the merging of local thought with wider European currents. Neapolitan Hegelians engaged very extensively with the works of French and northern Italian authors, such as Jules Michelet and Carlo Cattaneo, who had understood Vico as a proponent of an absolute concept of historical time that neatly dovetailed with the philosophical preoccupations common among German idealists. The article makes a case for a transnational understanding of Neapolitan Hegelianism, arguing that this current of thought did not merely stem from the passive absorption of Hegel’s ideas, but emerged as the synthesis of a local and a European dimension of philosophy.

High-voltage-gain DC-DC converter with three-winding coupled inductor

A novel DC-DC converter topology that uses a three-winding coupled inductor (TWCI) and a new voltage-multiplication technique is presented for achieving high voltage gain. The proposed converter comprises one boost unit, one passive absorption circuit, and two voltage-multiplier cells. The tertiary winding of the coupled inductor is connected to a capacitor and diode, and this combination acts as a secondary voltage-multiplier cell (SVMC). The SVMC, when combined with two capacitors, the secondary winding of the coupled inductor, a diode, and a switch, forms a primary voltage-multiplier cell, which can achieve a large voltage-conversion ratio that can be adjusted easily. The new voltage-multiplier technique can be used to decrease the number of capacitors and diodes, which improves the transformation efficiency. A prototype circuit with a nominal rating of 300 W is designed to verify the correctness of theoretical analysis.

Bioinspired Solar‐Heated Carbon Absorbent for Efficient Cleanup of Highly Viscous Crude Oil

AbstractEfficient cleanup of viscous crude oil spill is a worldwide challenge due to its sluggish flowability at room temperature. Conventional oil remediation methods using physical absorbers, skimmers, and vacuum technologies either demonstrate low absorption efficiency or have severe operational restrictions. Inspired by the highly efficient and passive transpiration process in trees, a solar‐heated carbon absorber (HC‐Wood) with an inherited wood structure of aligned channels for rapid crude oil absorption is reported. The unique porous structure of the carbon absorber can extend the light absorption paths, guide the direction of heat transport, and decrease the resistance to oil flows, endowing the carbon absorber a large efficiency of solar absorption (>99% of the incident irradiation), excellent thermal management, and fast capillarity‐driven oil absorption behavior. The low tortuosity of the porous structure together with the efficient solar‐thermal conversion enable the absorber to demonstrate a crude oil absorption rate of 1550 mL m−2 in 30 s under 1 sun irradiation, which is 10 times faster than previously reported results for passive absorption of viscous crude oil. Given the unique structural design, low operating cost, and rapid oil absorption speed, this work provides a promising solution for addressing catastrophic large‐area viscous oil spills.

Advances in transdermal insulin delivery.

Insulin therapy is necessary to regulate blood glucose levels for people with type 1 diabetes and commonly used in advanced type 2 diabetes. Although subcutaneous insulin administration via hypodermic injection or pump-mediated infusion is the standard route of insulin delivery, it may be associated with pain, needle phobia, and decreased adherence, as well as the risk of infection. Therefore, transdermal insulin delivery has been widely investigated as an attractive alternative to subcutaneous approaches for diabetes management in recent years. Transdermal systems designed to prevent insulin degradation and offer controlled, sustained release of insulin may be desirable for patients and lead to increased adherence and glycemic outcomes. A challenge for transdermal insulin delivery is the inefficient passive insulin absorption through the skin due to the large molecular weight of the protein drug. In this review, we focus on the different transdermal insulin delivery techniques and their respective advantages and limitations, including chemical enhancers-promoted, electrically enhanced, mechanical force-triggered, and microneedle-assisted methods.