Freestanding oxide membranes:synthesis,tunable physical properties,and functional devices

The study of oxide heteroepitaxy has been hindered by the issues of misfit strain and substrate clamping,which impede both the optimization of performance and the acquisition of a fundamental understanding of oxide systems.Recently,however,the development of freestanding oxide membranes has provided a plausible solution to these substrate limitations.Single-crystalline functional oxide films can be released from their substrates without incurring significant damage and can subsequently be transferred to any substrate of choice.This paper discusses recent advancements in the fabrication,adjustable physical properties,and various applications of freestanding oxide perovskite films.First,we present the primary strategies employed for the synthesis and transfer of these freestanding perovskite thin films.Second,we explore the main functionalities observed in freestanding perovskite oxide thin films,with special attention to the tunable functionalities and physical properties of these freestanding perovskite membranes under varying strain states.Next,we encapsulate three representative devices based on freestanding oxide films.Overall,this review highlights the potential of freestanding oxide films for the study of novel functionalities and flexible electronics.

Veno-venous-extracorporeal membrane oxygenation treatment for severe capillary leakage syndrome: A case report

BACKGROUND Capillary leak syndrome(CLS)is characterized by the leakage of large amounts of fluid and plasma proteins into the interstitial space,resulting in hypoalbuminemia,hypovolemic shock,elevated blood concentration,systemic progressive edema,and multiple serosal cavity effusion.Clinical syndromes such as cavity effusion pose a grave threat to the life and health of the patient.CASE SUMMARY A 58-year-old female patient was admitted to the hospital after being in a coma for 6 h following accidental ingestion of a pesticide.She was treated with phencyclidine hydrochloride and pralidoxime iodide for detoxification,mechanical ventilation to maintain oxygen supply,continuous renal replacement therapy to maintain the internal environment,and hemoperfusion to promote the excretion of toxins.She also received a transfusion of red blood cells and massive fluid resuscitation.However,her blood pressure was not maintained.The patient was diagnosed with CLS due to pesticide poisoning.Oxygenation was difficult to maintain under full ventilator support;therefore,veno-venous-extracorporeal membrane oxygenation(VV-ECMO)treatment was given 13 h after admission.Her oxygenation level improved,but a large amount of ascites and pleural effusion soon became apparent.We continued drainage with an indwelling drainage tube,and the ECMO flow stabilized.The leakage gradually decreased,and ECMO was discontinued 3 d later.On the 6th day,the patient recovered from unconsciousness,but on gastroscopic evaluation,severe erosions were found in her entire stomach.With the family’s consent,treatment was stopped,and the patient was discharged from the hospital on the 7th day.CONCLUSION ECMO,liquid resuscitation and management,and improvement in plasma colloidal osmotic pressure,circulation,and tissue oxygen supply are crucial in treating CLS.

Solid oxide membrane-assisted electrolytic reduction of Cr_(2)O_(3) in molten CaCl_(2)

Solid oxide membrane-assisted electrolytic reduction of solid Cr_(2)O_(3) to Cr in molten CaCl_(2) was performed using a sintered porous Cr_(2)O_(3) cathode paired with an yttria-stabilized zirconia(YSZ)tube anode containing carbon-saturated liquid copper alloy.Analyses of the reduction mechanism,ion migration behavior,and effects of cathode pellet porosity and particle size on the electrolysis products and reduction rate revealed that the cathode microstructure and electrolytic conditions were key factors influencing the electrolysis process.Optimal results were obtained when the cathode was characterized by high porosity and a small particle size because this combination of features contributed to ion migration.Good electrochemical activation was observed when cathode pellets prepared by 4 MPa molding followed by 2 h of sintering at 1150℃ were applied.The electrode reduction process(Cr^(3+)→Cr^(2+)→Cr)was promoted by high electrode voltages,and Cr metal was efficiently formed.The proposed method appears to be well suited for electrolytic Cr production because it does not require expensive pre-electrolysis techniques or generate harmful by-products.

Unexpected Selective Absorption of Lithium in Thermally Reduced Graphene Oxide Membranes

Lithium plays an increasingly important role in scientific and industrial processes, and it is extremely important to extract lithium from a high Mg^(2+)/Li^(+) mass ratio brine or to recover lithium from the leachate of spent lithiumion batteries. Conventional wisdom shows that Li^(+) with low valence states has a much weaker adsorption(and absorption energy) with graphene than multivalent ions such as Mg^(2+). Here, we show the selective adsorption of Li^(+) in thermally reduced graphene oxide(rGO) membranes over other metal ions such as Mg^(2+), Co^(2+), Mn^(2+),Ni^(2+), or Fe^(2+). Interestingly, the adsorption strength of Li^(+) reaches up to 5 times the adsorption strength of Mg^(2+),and the mass ratio of a mixed Mg^(2+)/Li^(+) solution at a very high value of 500 : 1 can be effectively reduced to 0.7 : 1 within only six experimental treatment cycles, demonstrating the excellent applicability of the rGO membranes in the Mg^(2+)/Li^(+) separation. A theoretical analysis indicates that this unexpected selectivity is attributed to the competition between cation–π interaction and steric exclusion when hydrated cations enter the confined space of the rGO membranes.

Methane Conversion to C_2 Hydrocarbons in Solid State Oxide Electrolyte Membrane Reactor

Provskite-type catalysts, Ln0.6 Sr0.4 FexCo1-x O3 (Ln = Nd,Pr, Gd, Sm, La, 0＜x＜1) and Ln0.8Na0.2CoO3(Ln= La,Gd, Sm) were synthesized, their catalytic properties in the oxidative coupling of methane (OCM) were examined in a fixed-bed reactor. The former group presented higher activity in the OCM, but the main product was carbon dioxide. While the later group showed lower activity but much higher selectivity to C2 hydrocarbons compared with the former. Electrochemical measurements were conducted in a solid oxide membrane reactor with La0.8 Na0.2CoO3 as catalyst. The results showed that methane was oxidized to carbon dioxide and ethane by two parallel reactions. Ethane was oxidized to ethene and carbon dioxide. A fraction of ethene was oxidized deeply to carbon dioxide. The total selectivity to C2 hydrocarbons exceeded 70%. Based on the experimental results, a kinetic model was suggested to describe the reaction results.

Poly(amide-6-b-ethylene oxide)/[Bmim][Tf2N] blend membranes for carbon dioxide separation

Poly（amide-6-b-ethylene oxide）（Pebax1657）/1-butyl-3-methylimidazo-lium bis[trifluoromethyl）sulfonyl]-imide（[Bmim][Tf2N]） blend membranes with different [Bmim][Tf2N] contents were prepared via solution casting and solvent evaporation method. The permeation properties of the blend membranes for CO2, N2,CH4 and H2 were studied, and the physical properties were characterized by differential scanning calorimeter（DSC） and X-ray diffraction（XRD）. Results showed that [Bmim][Tf2N] was dispersed as amorphous phase in the blend membranes, which caused the decrease of Tg（PE） and crystallinity（PA）. With the addition of [Bmim][Tf2N], the CO2 permeability increased and reached up to approximately 286 Barrer at 40 wt%[Bmim][Tf2N], which was nearly double that of pristine Pebax1657 membrane. The increase of CO2 permeability may be attributed to high intrinsic permeability of [Bmim][Tf2N], the increase of fractional free of volume（FFV） and plasticization effect. However, the CO2 permeability reduced firstly when the [Bmim][Tf2N]content was below 10 wt%, which may be due to that the small ions of [Bmim][Tf2N] in the gap of polymer chain inhibited the flexibility of polymer chain; the interaction between Pebax1657 and [Bmim][Tf2N]decreased the content of EO units available for CO2 transport and led to a more compact structure. For Pebax1657/[Bmim][Tf2N] blend membranes, the permeabilities of N2, H2 and CH4decreased with the increase of feed pressure due to the hydrostatic pressure effect, while CO2 permeability increased with the increase of feed pressure for that the CO2-induced plasticization effect was stronger than hydrostatic pressure effect.

Study on the Tin Oxide Sol-Gel Membrane as a pH Sensing Electrode

In this study,tin oxide sensing membrane was derived by sol-gel method and was coated onto indium tin oxide (ITO) glass substrate by spin-coating technique to fabricate a pH sensing electrode.Besides,the morphology of the tin oxide membrane has been discussed through the instrumental analysis.Furthermore,the sensing characteristics of the pH electrode was measured by commercial instrumental amplifier as the readout circuit.Owing to the sol-gel method has many advantages such as easy fabrication of gel solution,ability to dope other materials without any expensive fabricating equipment.Hence,it is suitable for the mass production of a disposable sensor.

Expression of inducible nitric oxide synthase induced by lipid-associated membrane proteins of Ureaplasma urealyticum is regulated by nuclear factor κB-mediated mechanism in murine macrophages

The aim was to investigate the molecular mechanisms responsible for the inducible nitric oxide synthase （iNOS） gene expression stimulated by lipid associated membrane proteins （LAMPs） of Ureaplasma urealytictan （ U. urealyticum ）. Detection of NO, the expression of iNOS and the activation of nuclear factor κB （NF-κB） in direct response to U. urealyticum LAMPs in a murine macrophages, the effects of pyrrolidine dithiocarbamate （PDTC）, an inhibitor of NF-κB and of cycloheximide （CHX）, a protein synthase inhibitor were available. The results indicated that U. urealyticum LAMPs stimulated mouse macrophages to express iNOS and thus produce NO in dose- and time-dependent manner by activating NF-κB. The expression of iNOS, NO production and the activation of NF-κB were inhibited by U. urealyticum LAMPs combination with PDTC or CHX. In conclusion, our findings suggest that U. urealyticum may be an etiological factor to certain diseases due to its ability to stimulate the expression of iNOS, which is probably mediated through the activation of NF-κB.

Synthesis and characterization of Ba_(0.5)Sr_(0.5)Co_(0.8)Fe_(0.2)O_(3-σ)

Perovskite-type Ba0.5Sr0.5Co0.8Fe0.2O3-σ （BSCFO） powders were synthesized using two methods, solid-state reaction （SSR） method and citrate-EDTA complexing method （CC-EDTA）. Then the powders were pressed to green disks of 19 nun in diameter and sintered at 1140℃ for 5 h. The shrinkage rate and relative density of the membranes prepared from the perovskite-type powders were determined and calculated, and the powders and derived membranes were characterized by X-ray diffraction （XRD） and scanning electron microscopy （SEM）. The resuits show that the shrinkage rates of the two kinds of disks are nearly the same （about 10%）. The disks prepared by the SSR method had a bigger grain size and lower relative density than those prepared by the CC-EDTA method. The conductivity of the membranes prepared by the SSR method was about 38 S/cm, higher than that of the membranes prepared by the CC-EDTA method, which was about 30 S/cm, at the same temperature of600℃.

Highly efficient separation of Sc^(3+) and Y^(3+) in acid solution by a graphene oxide membrane with interlayer sieving

Sc and Y are key rare earth elements and are widely used in lamp phosphors,lasers and high-performance alloys.However,highly efficient extraction and separation of Sc^(3+) and Y^(3+) is laborious,harmful,slow,and costly,strongly necessitating more efficient extraction and separation techniques.Here,we produced hydrated Sc^(3+)-and hydrated Y^(3+)-controlled graphene oxide(GO) membranes and find that both hydrated cations were completely self-rejected by the membrane.By combining this selfrejection effect of the larger hydrated Y^(3+)-controlled GO membrane and the rapid passage of the membrane through the smaller hydrated Sc^(3+),we proposed a strategy to separate Sc^(3+) and Y^(3+) by using a hydrated Y^(3+)-controlled GO membrane.The experimental results show that the permeation rate of Sc^(3+) exceeds that of Y^(3+) when the separation factor reaches 4.02,which can be attributed to the interlayer sieving effects of the GO membrane.Our finding illustrates the use of a forward osmosis process with a GO membrane for the efficient separation of Sc^(3+) and Y^(3+) by interlayer sieving,which provides a new effective and eco-friendly method for the separation of rare earth elements.

The use of graphene oxide membranes for the softening of hard water

Strong chemical interactions between the oxygen-containing functional groups on graphene oxide(GO)sheets and the ions of divalent metals were exploited for the softening of hard water.GO membranes were prepared and evaluated for their ability to absorb Ca2+and Mg2+ions.These GO membranes can effectively absorb Ca2+ions from hard water;a 1 mg GO membrane can remove as much as 0.05 mg Ca2+ions.These GO membranes can be regenerated and used repeatedly.

Constructing 2D ultrathin graphene oxide membranes with supramolecular-assembled nano-adhesives for enhancing water stability

Atomic-thick two-dimensional(2D)graphene oxide(GO)has emerged as an ideal building block in developing ultrathin 2D membranes for separating substances.However,due to the negative charge of GO sheets when hydrated,electrostatic repulsion causes GO membranes to disintegrate easily in water,limiting their wide application in aqueous solutions.Here,we introduce and apply the concept of localized gluing by designing ultra-small supramolecular-assembled nanoparticles as nanoadhesives(NPA)to construct robust GO membranes with a thickness of only 24 nm.The supramolecular-assembled NPA were synthesized by cyclodextrin(CD)and tannic acid(TA)with a uniform size distribution of about 4.5 nm,and exposed surface pyrogallols that could strongly interact with GO sheets.The physical sizing of the NPA confines the interlayer spacing and maintains the nanochannel,while the natural molecular properties of the NPA enhance the connection between adjacent layers and inhibit swelling detachment.The fabricated ultrathin 2D membranes show a remarkable two times enhancement of water permeance over pristine GO membranes and exhibit excellent durability with record-breaking stability for 720 h immersion in water.This strategy provides meaningful insights into the design and fabrication of robust ultrathin membranes for practical application.

Hydrophilic/underwater superoleophobic graphene oxide membrane intercalated by TiO2 nanotubes for oil/water separation

Membrane technology for oil/water separation has received increasing attention in recent years. In this study, the hydrophilic/underwater superoleophobic membrane with enhanced water permeability and antifouling ability were fabricated by synergistically assembling graphene oxide （GO） nanosheets and titanium dioxide （TiO2） nanotubes for oil/water separation. GO/TiO2 membrane exhibits hydrophilic and underwater superoleophobic properties with water contact angle of 62° and under water oil contact angle of 162.8°. GO/TiO2 membrane shows greater water permeability with the water flux up to 531 L/ （m^2·h·bar）, which was more than 5 times that of the pristine GO membrane. Moreover, GO/TiO2 membrane had excellent oil/water separation efficiency and anti-oil-fouling capability, as oil residual in filtrate after separation was below 5 mg/L and flux recovery ratios were over 80%.The results indicate that the intercalation of TiO2 nanotubes into adjacent GO nanosheets enlarged the channel structure and modified surface topography of the obtained GO/TiO2 membranes, which improved the hydrophilicity, permeability and anti-oil-fouling ability of the membranes, enlightening the great prospects of GO/TiO2 membrane in oil-water treatment.

Theoretical study on Janus graphene oxide membrane for water transport

Graphene oxide(GO)membranes have received considerable attention owing to their outstanding water-permeation properties;however,the effect of the membrane’s microstructures(such as the distribution of oxidized and pristine regions)on the transport mechanism remains unclear.In this study,we performed molecular simulations to explore the permeation of a water-ethanol mixture using a new type of Janus GO membranes with different orientations of oxidized and pristine surfaces.The results indicate that the oxidized upper surface endows the GO membrane with considerable water-capture capability and the in-built oxidized interlayer promotes the effective vertical diffusion of water molecules.Consequently,using the optimized Janus GO membrane,infinite water selectivity and outstanding water flux(-40.9 kg·m^(-2) h^(-1))were achieved.This study contributes to explaining the role of oxidized regions in water permeation via GO membranes and suggests that Janus GO membranes could be used as potential candidates for water-ethanol separation.

Effect of oxide nanoparticles on the morphology and fluidity of phospholipid membranes and the role of hydrogen bonds

Engineered oxide nanoparticles（NPs） are widely applied in insulators,catalyzers,paints,cosmetic products,textiles and semiconductors.Their attachment on cell membrane may lead to cytotoxicity.The effects of Al_2O_3,Fe_2O_3,SiO_2,TiO_2and ZnO NPs on membrane integrity and fluidity were studied using giant or small unilamellar vesicles in this study.Al_2O_3 and SiO_2NPs disrupted the oppositely charged membrane,indicating the important role of electrostatic attraction.However,Fe_2O_3,TiO_2and ZnO NPs did not cause serious membrane disruption as Al_2O_3 and SiO_2 NPs.Membrane fluidity was evaluated by the generalized polarity（GP） values of Laurdan fluorescent emission.SiO_2 NPs induce the membrane gelation of both positively and negatively charged membrane.Al_2O_3 and ZnO NPs induced the gelation of the oppositely charged membrane,but did not cause obvious membrane gelation to the like charged membrane.The phospholipid molecular structural changes after NP exposure were analyzed by Fourier transform infrared（FT-IR） spectroscopy.FT-IR spectra revealed the hydrogen bond formation between NPs and the carbonyl/phosphate groups of phospholipids.Al_2O_3 and SiO_2 NPs showed strongest evidence of hydrogen bonding on their FT-IR spectra.It was consistent with the microscopic observation and fluorescent data that Al_2O_3 and SiO_2 NPs caused more serious membrane disruption and gelation.This study on membrane damage provides further knowledge on the cytotoxicity of nanomaterials and the safety of NP application.

Ion sieving in graphene oxide membranes via cationic control of interlayer spacing

With the support by the National Natural Science Foundation of China,a collaborative study by the research groups led by Prof.Fang Haiping(方海平)from Shanghai Institute of Applied Physics,Chinese Academy of Sciences,Prof.Wu Minghong(吴明红)from Shanghai Applied Radiation Institute。

Phase-selective graphene oxide membranes for advanced microfluidic flow control

For the first time,we harness the unique phase-selectivity of chip-integrated graphene oxide(GO)membranes to significantly enhance flow control on centrifugal microfluidic platforms.In this paper,we present novel processes for the assembly of these GO membranes into polymeric microfluidic systems and demonstrate that multilayer GO membranes allow the passage of water while blocking pressurized air and organic solutions.