Plastic Membrane Research Articles

Elastic effect on the final deflection of rigid-plastic square plates under pulse loading

Rigid-perfectly plastic (R-PP) models are widely employed in the study of structural impact dynamics. However, due to the complexity of dynamic elastic-plastic behavior and the limitations of numerical simulation, it is of great significance to evaluate the elastic effect on the structural response to pulse loading. This paper examines the validity of the R-PP theoretical solutions on large deflection of pulse-loaded square plates. First, by exploring the characteristic of “plastic membrane” and considering the effect of membrane forces and bending moments on energy dissipation, an energy ratio R and a characteristic time ratio are precisely defined. Then based on the R-PP complete solutions recently developed for square plates under rectangular pressure pulse, the discrepancies in final deflection and in saturated impulse between the R-PP theoretical predictions and the elastic-perfectly plastic (E-PP) simulation results are evaluated and elaborated. It is revealed that the discrepancy in final deflection is dependent on the dimensionless stiffness ζplate and the dimensionless pulse magnitude λ. Moreover, the discrepancies in final deflection are compared between square plates and beams via a thorough analysis of key parameters, indicating that most characteristics of the elastic effect are similar for both cases, i.e., the R-PP solutions for both square plates and beams can reliably provide theoretical predictions for engineering applications if energy ratios R>5, with no limitation on the pulse duration. With the same geometric and material parameters, however, the energy ratio R of square plates is about twice that of beams, the discrepancy in final deflection of plates is larger than that of beams, but the absolute value of the discrepancy in final deflection for the clamped square plates remains in the order of 1/(1.5R) and can be bounded by 1/[4λ(λ-1)].

All-in-one membrane micro-supercapacitors for implantable devices

The integration of energy storage devices into a single design is crucial for achieving a stable and efficient energy supply for implantable electronic devices that are compatible with soft human organs and tissues. Here we present a novel approach to fabricate all-in-one flexible energy storage devices based on phase inversion engineering of plastic polyethersulfone membrane. This method is simple, controllable, and highly scalable, and the membrane devices have no extra separator and electrolyte. Furthermore, one can effectively control the membrane structure, hydrophilicity, mechanical property, and electrochemical performance by regulating the content and kinds of active material, additives amount, and device thickness. The obtained all-in-one supercapacitor is very thin and light, with a mass of only 6.3 mg per 1.2 × 1.2 × 0.01 cm3, and applied in an opening-up system within a body fluid environment with good electrochemical performance (3.01 F cm−3 at 0.1 A cm−3), mechanical properties (Young’s modulus is similar to the biological tissue), and long-term stability (capacitance retention of 94.03% after 40, 000 cycles). This plastic polymer-based membrane device has excellent biocompatibility and can be used as power supply systems, including supercapacitors and batteries for long-life, miniaturized implantable devices.

An innovative design approach for anchored wire meshes

AbstractAnchored wire meshes are commonly adopted to stabilize potentially unstable soil slopes. This reinforcement technique, employed either as an active or a passive anchoring system, is commonly designed according to ultimate limit state approaches. In this paper, an interaction model, useful for the design of anchored wire meshes, is proposed. The model is based on the results of a series of 3D large displacement finite element numerical analyses, in which the wire mesh mechanical behaviour is modelled as either an elastic or an elastic–plastic membrane. The model is inspired to standard load–displacement curves for shallow foundations, and the wire mesh presence is taken into account by suitably modifying the bearing capacity formula. The proposed model predictions are compared with experimental punching test results. The use of the model, only requiring the definition of geometry and soil–wire mesh mechanical properties, allows the pre-design of the reinforcement system without performing ad hoc finite element numerical analyses.

Cross-linked PI membranes with simultaneously improved CO2 permeability and plasticization resistance via tunning polymer precursor orientation degree

Polyimides (PIs) have gained recognition as highly desirable membrane materials for efficient CO2/CH4 separation. However, the practical utilization of these materials has been impeded by the issue of the substantial susceptibility to plasticization when exposed to high-feed-pressure conditions. Although thermal cross-linking has been widely employed to enhance plasticization resistance in PI membranes, cross-linking will normally sacrifice CO2 permeability. Thus, the advancement of PI membranes that exhibit both remarkable CO2 permeability and exceptional plasticization resistance is highly desired. The current work designed a series of cross-linkable PIs with different polymer chain orientation degrees. Different from conventional PIs, by properly controlling the polymer chain orientation, the CO2 permeability can be enhanced by 2.3 times without compromising the membrane plasticization resistance. Various techniques, including FTIR, WAXD, TGA, and DMA, were employed to thoroughly characterize the obtained membranes. These characterizations verified that optimizing the polymer chain orientation constitutes an efficacious strategy to enhance the resistance of PI membranes against plasticization, while simultaneously preserving their CO2 permeability. Additionally, the thermally cross-linked membranes exhibited good long-term stability during an 1100-h test.

Synthesis of trioctyl polyvinyl chloride ammonium, membrane extraction properties, and electrodriven mass transfer behavior of Chromium (VI)

Trioctyl polyvinyl chloride ammonium (PVCTQAS) with quaternary ammonium salt content (QAS) of 25 % was synthesized by a nucleophilic substitution reaction of between polyvinyl chloride (PVC) and trioctylamine (TOA) for the first time. The mass transfer behavior of HCrO4−, CdCl3−, CoCl42−, FeCl4−, and CuCl42− metal complex anions within the plasticized PVCTQAS membrane followed a first-order kinetic rate equation. Taking the Cr(Ⅵ)-PVCTQAS system as a representative, the influences of plasticizer content and membrane thickness on the mass transfer performance were investigated, and the electrodriven mass transfer behavior of Cr(VI) was studied. The results showed that the mass transfer of HCrO4− in PVCTQASD followed a jumping mechanism, with a QAS content threshold of 22 %. In the Cr(VI)-PVCTQAS electrodriven mass transfer system, the PVCTQASD exhibited uniform electrochemical properties, and the membrane thickness had little influence on the mass transfer rate. The response of HCrO4− mass transfer rate to voltage depended on the distribution density of QAS in the membrane. The mass transfer performance of PVCTQASD with QAS between 15 % and 20 % had a high dependence on the voltage, while the permeability coefficient of Cr(VI)-PVCTQAS system became stable when the voltage exceeded 10 V after surpassing the QAS content threshold. 50 μm QAS 25 % Cr(VI)-PVCTQAS system had a treatment efficiency of 710 mg·m−2·h−1 for HCrO4− at 10 V, while maintaining exceptional selectivity and stability.

Highly selective potentiometric determination of nitrate ions using silver bisdiethyldithiocarbamate based membrane electrodes

A new all-solid-state PVC membrane nitrate electrode was developed and nitrate ions were potentiometrically analyzed. Silver (I) bisdiethyldithiocarbamate ((C2H5)2NCS2)2Ag+) (Ag(dtc)2) compound was used as electroactive positive charged carrier (ionophore) in the plasticized PVC membrane structure of the developed electrode. The developed nitrate selective polymeric membrane electrode (nitrate-ISE) exhibited linear potentiometric behavior in the concentration range of nitrate ions from 1.0 × 10−1 to 1.0 × 10−5 mol L−1 and the detection limit was determined as 6.71 × 10−6 mol L−1. Although nitrate-ISE has good reproducibility, the pH working range is determined to be 4 – 9. The proposed nitrate-ISE has been successfully applied for the determination of nitrate ions in different water samples and fruit juices.

Plastic membrane sensor for the determination of hydroxyzine dihydrochloride in the pharmaceutical formulation

The construction and performance characteristics of a plastic membrane potentiometric sensor for the determination of hydroxyzine dihydrochloride were described. The sensor is based on hydroxyzine-tetraphenylborate ion pair as an electroactive species and dibutyl phthalate as a plasticizer. The proposed sensor has a nernstian slope of 58 + 1.23 mV concentration per decade at 25 °C in the concentration range 1.96 × 10−5 – 1 × 10−2 M hydroxyzine dihydrochloride with a detection limit of 6.34 × 10−6 M (2.84 µg/ ml) hydroxyzine dihydrochloride, and the response time was 10 s. The sensor shows good selectivity for the drug over many inorganic cations, sugars, vitamins and, amino acids. The suggested sensor was effectively employed for the determination of the drug in its pharmaceutical formulation Atarax injection and in spiked human urine samples.

Ionic Liquid-Assisted Antibacterial Membranes: Successful Preparation and Enhanced Antibacterial Effect

In this study, we synthesized a supramolecular antibacterial ionic salt, [PHMB][Sal], based on poly(hexamethylene biguanide) hydrochloride (PHMB) and sodium salicylate (SS) to endow plastic membranes with antibacterial function. The antibacterial composites of polyelectrolyte-nonsteroidal ionic salt can be blended with polymer materials, such as polybutylene adipate terephthalate (PBAT), because the melting point of the salt can be coordinated with that of the polymer material. The properties of the prepared membranes containing polyelectrolyte-nonsteroidal ionic salts did not change significantly. The mechanical properties and antimicrobial activities of the prepared hydrophobic membranes were investigated. When 3% of [PHMB][Sal] was added, the antimicrobial activities against Gram-positive Staphylococcus aureus and Escherichia coli were 4.12 and 4.30, respectively, and the antibacterial rate was as high as 99.9%, exhibiting extremely excellent antimicrobial properties. Biodegradable [PHMB][Sal] membrane materials are expected to be used in medical environments as well as on packaging surfaces in logistics, which can effectively prevent bacterial cross-infection.

MYRINGOPLASTY WITH APPLICATION XENOGRAFT FROM SHEEP PERICARDIA

To date, there is no consensus on the question of which tissues are more appropriate to use for tympanic membrane plastic surgery. We decided to study the use of xenograft from sheep pericardium in myringoplasty in rabbits in the experiment, and in patients with chronic dry mesotympanitis. Experimental morphological studies using a xenograft were carried out in 28 rabbits. In the experiment, a positive result was obtained in 25 (89.3%) rabbits. In addition, 77 patients with dry perforation of the tympanic membrane were examined. To compare the results of the study, these patients underwent myringoplasty: 54 patients with the use of a xenograft from the sheep pericardium, 23 patients with the use of the fascia of the temporal muscle. Reliable engraftment of a xenograft from sheep pericardium after surgery was observed in 48 patients (88.9%), and with the use of temporal muscle fascia in 20 patients (86.9%).

MORPHOLOGICAL RESULTS WITH THE APPLICATION OF A XENOGRAFT IN EXPERIMENTAL TYMPANOPLASTY

To date, there is no consensus on the question of which tissues are more appropriate to use for tympanic membrane plastic surgery. We decided to study the use of xenograft from sheep pericardium in tympanoplasty in rabbits in an experiment with chronic dry mesotympanitis. Experimental morphological studies using a xenograft were carried out in 28 rabbits. In the experiment, a positive result was obtained in 25 (89.3%), negative in 3 (10.7%) rabbits.

Types of cell culture inserts affect cell crosstalk between co-cultured macrophages and adipocytes

Cell culture inserts offer an in vivo-like microenvironment to investigate cell-cell interactions between co-cultivated cells. However, it is unclear if types of inserts affect cell crosstalk. Here, we developed an environment-friendly cell culture insert, XL-insert, which can reduce plastic waste with lower cost. We compared XL insert with two types of commercial disposable culture inserts, Koken® insert with atelocollagen membrane (Col-inserts) and Falcon® inserts with plastic membrane (PET-inserts) on cell-cell interactions in co-cultivated THP-1 macrophages and OP9 adipocytes. Scanning electron microscope, immunoassay and imaging analysis showed that among three types of inserts, XL-inserts allowed cytokines from co-cultivated macrophages and adipocytes to diffuse freely and offered preferable in vivo-like microenvironment for cell-cell interactions. PET-inserts showed limitations for intercellular communication due to some pores being blocked by somas on the membrane that caused much lower permeability for cytokines passing through. Col-inserts blocked large sized cytokines but allowed small sized molecules to permeate resulting in improved lipid accumulation and adiponectin secretion in OP9 adipocytes. Taken together, our data demonstrated that membrane type and pore size on the membrane affect the cross-talk between co-cultivated cells very differently. Some previous co-culture studies might have different results if the inserts were changed.

The pattern of photosynthetic response and adaptation to changing light conditions in lichens is linked to their ecological range

Epiphytic lichens constitute an important component of biodiversity in both deforested and forest ecosystems. Widespread occurrence is the domain of generalist lichens or those that prefer open areas. While, many stenoecious lichens find shelter only in a shaded interior of forests. Light is one of the factors known to be responsible for lichen distribution. Nevertheless, the effect of light intensity on photosynthesis of lichen photobionts remain largely unknown. We investigated photosynthesis in lichens with different ecological properties in relation to light as the only parameter modified during the experiments. The aim was to find links between this parameter and habitat requirements of a given lichen. We applied the methods based on a saturating light pulse and modulated light to perform comprehensive analyses of fast and slow chlorophyll fluorescence transient (OJIP and PSMT) combined with quenching analysis. We also examined the rate of CO2 assimilation. Common or generalist lichens, i.e. Hypogymnia physodes, Flavoparmelia caperata and Parmelia sulcata, are able to adapt to a wide range of light intensity. Moreover, the latter species, which prefers open areas, dissipates the excess energy most efficiently. Conversely, Cetrelia cetrarioides considered an old-growth forest indicator, demonstrates definitely lower range of energy dissipation than other species, although it assimilates CO2 efficiently both at low and high light. We conclude that functional plasticity of the thylakoid membranes of photobionts largely determines the dispersal abilities of lichens and light intensity is one of the most important factors determining the specificity of a species to a given habitat.

A Bioinspired Robot Growing like Plant Roots

Plants are usually considered static organisms, but they can perform a wide range of movements that can be a source of inspiration for robots. The roots’ growing motion is the most noteworthy since they are excellent diggers that can move in unstructured environments and navigate past barriers. Furthermore, root growth has a high energy efficiency since it penetrates the soil at its tip, adding new material without displacing the already grown portion, minimizing the energy dissipation due to friction and lowering the inertia. A robot inspired by the growth of roots could be used in search and rescue or environmental monitoring. The design of a soft robot inspired by root growth is presented in this article. The robot body consists of a cylindrical plastic membrane folded inside itself. The robot body is inflated, and its tip is everted, expanding its length as air is blown from the base. Velcro straps are placed on the membrane’s exterior surface to keep it folded. The head is positioned inside the tip, which houses the mechanism that controls the growth direction. It consists of housing for two balloons that are selectively inflated, and their expansion applies pressure on the exterior surface, opening the Velcro straps and determining the growth direction. The robot was constructed, and a kinematic model of its motion in the plane was created and compared with experimental data. The error in predicting the turning angle is only 5%, and the resulting predicted position differs on average by 55 mm on a total length of 850 mm.

Development of the New Sensor Based on Functionalized Carbon Nanomaterials for Promethazine Hydrochloride Determination

Promethazine hydrochloride (PM) is a widely used drug so its determination is important. Solid-contact potentiometric sensors could be an appropriate solution for that purpose due to their analytical properties. The aim of this research was to develop solid-contact sensor for potentiometric determination of PM. It had a liquid membrane containing hybrid sensing material based on functionalized carbon nanomaterials and PM ions. The membrane composition for the new PM sensor was optimized by varying different membrane plasticizers and the content of the sensing material. The plasticizer was selected based on calculations of Hansen solubility parameters (HSP) and experimental data. The best analytical performances were obtained using a sensor with 2-nitrophenyl phenyl ether (NPPE) as the plasticizer and 4% of the sensing material. It had a Nernstian slope (59.4 mV/decade of activity), a wide working range (6.2 × 10-7 M-5.0 × 10-3 M), a low limit of detection (1.5 × 10-7 M), fast response time (6 s), low signal drift (-1.2 mV/h), and good selectivity. The working pH range of the sensor was between 2 and 7. The new PM sensor was successfully used for accurate PM determination in a pure aqueous PM solution and pharmaceutical products. For that purpose, the Gran method and potentiometric titration were used.

Waste to treasure: A superwetting fiber membrane from waste PET plastic for water-in-oil emulsion separation

Polyethylene terephthalate (PET) plastic membrane has attracted significant attention in chemical separation and pollution control due to its high mechanical properties and excellent chemical stability. However, designing inexpensive and efficient PET membrane materials for oil-water separation from waste PET plastics is still challenging but of great significance to environmental safety and resource protection. In this work, a superwetting PET fiber membrane with excellent structural stability and wetting selectivity was prepared from waste PET plastic, via electrostatic spinning, in-situ deposition and surface modification. The obtained superwetting PET fiber membrane exhibits the flourishing pore structure, wettability of superhydrophobic/super-oleophilic, and corrosion resistance (weak acid, strong base). Due to its stable porous structure and wettability properties, the membrane is capable of separating multi-type water-in-oil emulsion successfully, while with ideal separation flux (over 1100 L ·m−2·h−1), and separation efficiency (99.0–99.9%). Additionally, after the reusability tests with the least number of 40 cycles, the membrane shows favorable separation stability and excellent reusing performance, which possesses tremendous potential for efficient and continuous separation of water-in-oil emulsions. Therefore, the simple yet effective waste-to-resource strategy for waste PET plastic can not only reduce the environmental pollution caused by microplastics, but also develop an inexpensive and efficient membrane material for industrial emulsion separation.

Biophysical adaptations of cell membranes to hydrostatic pressure: From deep-sea marine invertebrates to model microorganisms.

Life in the deep ocean and continental subsurface is estimated to make up more than half of all biomass on the planet, and must withstand the crushing pressures up to 1000 times that at the surface. Lipid membranes encapsulating cells and organelles are sensitive to their physical environments, especially pressure. To understand the mechanisms by which membrane structure adapts to high pressure environments, we have employed lipidomic and structural analyses of extracted membranes from pressure-adapted deep-sea invertebrates (ctenophores), allowing us to identify key chemical and physical signatures of depth adaptation. To validate these findings, we employed yeast and bacterial model organisms, engineered with tuned lipid biosynthesis pathways, and grown under varying pressures in the lab. This multi-scale, comparative approach has revealed lipid properties such as headgroup stoichiometry, ether vs. ester chain linkages, chain unsaturation, and chain length length provide biophysical advantages to buffer against physiologically-incompatible membrane states and preserve membrane plasticity at high pressure. Understanding lipid adaptations to pressure could allow for the identification of the mechanisms by which cells sense the global membrane environment and thereby facilitate homeoviscous, homeophasic, and homeocurvature responses.

Ionic Microporous Polymer Membranes for Advanced Gas Separations

Microporous polymers are uniquely attractive for membrane-mediated gas separations; however, conventional microporous polymers suffer a ubiquitous trade-off between gas permeability and selectivity, leading to bottlenecks in their practical applications. Functionalization of microporous polymers via molecule engineering is an effective way to enhance their gas separation performance and processability. This review outlines the research progress of ionization to improve the gas separation performance of typical microporous polymers (e.g., polymers of intrinsic microporosity (PIM), perfluorinated polymers, microporous polyimides, etc.) and summarizes the different ionization methods, including carboxylation, sulfonation, quaternization, and other ionization processes. Additionally, the review also explores the research progress of ionization to regulate the processability, microporosity, and gas separation properties of microporous polymers. Specifically, ionization can effectively tailor the microporosity, improve the solubility coefficients of gas molecules, especially CO2, and enhance gas selectivities. In addition, ionization can improve the processability of PIMs and enhance the membrane plasticization resistance. Ionic microporous polymers provide an essential platform for developing energy-efficient and high-performance gas separation membranes.

Swelling and plasticization of the polymer membrane under the influence of contaminants containing hydrogen sulfide

Swelling and plasticization of the polymer membrane under the influence of contaminants containing hydrogen sulfide

Sensing and extraction of hazardous metals by di-phosphonates of heterocycles: a combined experimental and theoretical study.

In this study, pyridine and phenanthroline diphosphonate ligands were investigated for the first time from the context of solvent extraction and potentiometric sensing of Co(II), Ni(II), Cu(II), Zn(II), Cd(II), and Pb(II) cations. The extraction efficiency under the same conditions for phenanthroline-diphosphonates is considerably higher than that for pyridine ligands. At the same time, the pyridine-diphosphonates show pronounced selectivity towards lead in this metal series. The extraction systems with phenanthroline diphosphonates provided the most efficient extraction of Cd(II) and Pb(II) cations (D > 90). The newly developed pyridine and phenanthroline diphosphonate ligands have proven to be highly effective components in plasticized polymeric membranes. These ligands can be utilized to construct potentiometric ion sensors that exhibit a notable response specifically towards Pb(II) cations. Among the previously reported tetradentate ligands, the phenanthroline diphosphonate ligand, when incorporated into plasticized polymeric membranes, demonstrated the highest sensitivity towards d-metals and Pb(II). The structure of the single crystal complex of Pb(II) and Cd(II) with pyridine-diphosphonates was studied by X-ray diffraction analysis (XRD). The geometry of Cu(II), Zn(II), Cd(II) and Pb(II) complexes and the energy effect of the complex formation, including pseudo-oligomerization reactions, were determined by DFT calculations. The high sensing and extraction efficiency of diphosphonates with respect to Pb(II) is consistent with the minimum values of complex formation energies. The variation in sensory and extraction properties observed among the studied diphosphonate ligands is influenced by the ability to form polynuclear complexes with Pb(II) cations, whereas such properties are absent in the case of Cd(II) cations.

Ion-Selective Membrane Electrode for Determination of the Octahydrotriborate Anion

An ion-selective electrode (ISE) based on a plasticized polyvinyl chloride membrane chemically doped with tetradecylammonium octahydrotriborate ([(С10H21)4N+]) has been developed. It is shown that the electrode has a reversible potentiometric response with respect to the octahydrotriborate anion in the presence of a number of other inorganic anions. The influence of the concentration of the electrode-active material and the nature of the plasticizer in the membrane phase on the electrochemical characteristics of the fabricated sensor have been studied. The optimal composition of the ion-sensitive membrane has been found. It has been found that the developed sensor provides a wide range of detectable concentrations of(1 × 10–7…1 × 10–2) and a low detection limit (10–7.3 M). The new ISE can be recommended for direct potentiometric detection of free octahydrotriborate anions in technological aqueous solutions.