Three-Dimensional Morphology of Polymeric Membranes from Electron Tomography.

Recent advances in the water-energy landscape hinge upon our improved understanding of the complex morphology of materials involved in water treatment and energy production. Due to their versatility and tunability for applications ranging from drug delivery to fuel cells, polymeric systems will play a crucial role in shaping the future of water-energy nexus applications. Electron tomography (ET) stands as a transformative approach for elucidating the intricate structures inherent to polymers, offering unparalleled insights into their nanoscale architectures and functional properties in three dimensions. In particular, the various morphological and chemical characteristics of polymer membranes provide opportunities for perturbations to standard ET for the study of these systems. We discuss the applications of transmission electron microscopy in establishing structure-function relationships in polymeric membranes with an emphasis on traditional ET and cryogenic ET (cryo-ET). The synergy between ET and cryo-ET to unravel structural complexities and dynamic behaviors of polymer membranes holds immense potential in driving progress and innovation across frontiers related to water-energy nexus applications. Expected final online publication date for the Annual Review of Chemical and Biomolecular Engineering , Volume 15 is June 2024. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.

Cold Sintering Enables the Reprocessing of LLZO-Based Composites.

All-solid-state batteries have the potential for enhanced safety and capacity over conventional lithium ion batteries, and are anticipated to dominate the energy storage industry. As such, strategies to enable recycling of the individual components are crucial to minimize waste and prevent health and environmental harm. Here, we use cold sintering to reprocess solid-state composite electrolytes, specifically Mg and Sr doped Li7 La3 Zr2 O12 with polypropylene carbonate (PPC) and lithium perchlorate (LLZO-PPC-LiClO4 ). The low sintering temperature allows co-sintering of ceramics, polymers and lithium salts, leading to re-densification of the composite structures with reprocessing. Reprocessed LLZO-PPC-LiClO4 exhibits densified microstructures with ionic conductivities exceeding 10-4  S/cm at room temperature after 5 recycling cycles. All-solid-state lithium batteries fabricated with reprocessed electrolytes exhibit a high discharge capacity of 168 mA h g-1 at 0.1 C, and retention of performance at 0.2 C for over 100 cycles. Life cycle assessment (LCA) suggests that recycled electrolytes outperforms the pristine electrolyte process in all environmental impact categories, highlighting cold sintering as a promising technology for recycling electrolytes.

Improvement of oxygen reduction activity and stability on a perovskite oxide surface by electrochemical potential.

The instability of the surface chemistry in transition metal oxide perovskites is the main factor hindering the long-term durability of oxygen electrodes in solid oxide electrochemical cells. The instability of surface chemistry is mainly due to the segregation of A-site dopants from the lattice to the surface. Here we report that cathodic potential can remarkably improve the stability in oxygen reduction reaction and electrochemical activity, by decomposing the near-surface region of the perovskite phase in a porous electrode made of La1-xSrxCo1-xFexO3 mixed with Sm0.2Ce0.8O1.9. Our approach combines X-ray photoelectron spectroscopy and secondary ion mass spectrometry for surface and sub-surface analysis. Formation of Ruddlesden-Popper phase is accompanied by suppression of the A-site dopant segregation, and exsolution of catalytically active Co particles onto the surface. These findings reveal the chemical and structural elements that maintain an active surface for oxygen reduction, and the cathodic potential is one way to generate these desirable chemistries.

A multiscale ion diffusion framework sheds light on the diffusion-stability-hysteresis nexus in metal halide perovskites.

Stability and current-voltage hysteresis stand as major obstacles to the commercialization of metal halide perovskites. Both phenomena have been associated with ion migration, with anecdotal evidence that stable devices yield low hysteresis. However, the underlying mechanisms of the complex stability-hysteresis link remain elusive. Here we present a multiscale diffusion framework that describes vacancy-mediated halide diffusion in polycrystalline metal halide perovskites, differentiating fast grain boundary diffusivity from volume diffusivity that is two to four orders of magnitude slower. Our results reveal an inverse relationship between the activation energies of grain boundary and volume diffusions, such that stable metal halide perovskites exhibiting smaller volume diffusivities are associated with larger grain boundary diffusivities and reduced hysteresis. The elucidation of multiscale halide diffusion in metal halide perovskites reveals complex inner couplings between ion migration in the volume of grains versus grain boundaries, which in turn can predict the stability and hysteresis of metal halide perovskites, providing a clearer path to addressing the outstanding challenges of the field.

Reactive Oxygen Species-Triggered Hydrogen Sulfide Release and Cancer-Selective Antiproliferative Effect of Anethole Dithiolethione-Containing Polymeric Micelles.

Hydrogen sulfide (H2 S) is a gaseous signaling molecule in the human body and has attracted attention in cancer therapy due to its regulatory roles in cancer cell proliferation and migration. Accumulating evidence suggests that continuous delivery of H2 S to cancer cells for extended periods of time suppresses cancer progression. However, one major challenge in therapeutic applications of H2 S is its controlled delivery. To solve this problem, polymeric micelles are developed containing H2 S donating-anethole dithiolethione (ADT) groups, with H2 S release profiles optimal for suppressing cancer cell proliferation. The micelles release H2 S upon oxidation by reactive oxygens species (ROS) that are present inside the cells. The H2 S release profiles can be controlled by changing the polymer design. Furthermore, the micelles that show a moderate H2 S release rate exert the strongest anti-proliferative effect in human colon cancer cells in in vitro assays as well as the chick chorioallantoic membrane cancer model, while the micelles do not affect proliferation of human umbilical vein endothelial cells. This study shows the importance of fine-tuning H2 S release profiles using a micelle approach for realizing the full therapeutic potential of H2 S in cancer treatment.

Single High-Dose Systemic Methylprednisolone Administered Preoperatively Improves Pain Control and Sleep Quality After Total Hip Arthroplasty: A Double-Blind, Randomized Controlled Trial.

Background: This study was performed to evaluate the efficacy of preoperative high-dose methylprednisolone on pain levels and sleep quality following primary total hip arthroplasty. Material and methods: A double-blind, randomized controlled trial was performed in adults underdoing total hip arthroplasty. A computer-generated, permuted-block randomization scheme with a 1:1 ratio between the intervention (125 mg methylprednisolone) and control groups (normal saline) was utilized. Patients underwent a similar preoperative and postoperative protocol. Pain was assessed using the visual analog scale (VAS). Sleep quality was assessed at the 2-week postoperative visit using the Pittsburgh Sleep Quality Index (PSQI). Results: With a total of 70 patients, 35 patients were included in the intervention and placebo groups. Hospital stay was significantly shorter in the intervention group (1.5 ± 0.7 vs 2.0 ± 0.5 days, P = .03). Preoperative pain levels were similar between groups, while satisfactory pain control was achieved in a significantly larger number of patients in the intervention group (18 vs 8 patients, P = .009). The intervention group was significantly more likely to have a good sleep quality than the placebo groups (74% vs 31%, P = .001). No significant differences were found between preoperative and postoperative blood sugar levels. We did not observe any cases of early postoperative wound complication, infection, or deep vein thrombosis among our patients. Conclusion: In this randomized controlled trial, preoperative administration of 125 mg of methylprednisolone was found to improve pain control, as measured by VAS, 24 hours after surgery, and sleep quality, as measured by PSQI, 2 weeks following surgery.

Thioether-Based Polymeric Micelles with Fine-Tuned Oxidation Sensitivities for Chemotherapeutic Drug Delivery.

Oxidation-sensitive drug delivery systems (DDSs) have attracted attention due to the potential to improve efficacy and safety of chemotherapeutics. These systems are designed to release the payload in response to oxidative stress conditions, which are associated with many types of cancer. Despite extensive research on the development of oxidation-sensitive DDS, the lack of selectivity toward cancer cells over healthy cells remains a challenge. Here, we report the design and characterization of polymeric micelles containing thioether groups with varying oxidation sensitivities within the micellar core, which become hydrophilic upon thioether oxidation, leading to destabilization of the micellar structure. We first used the thioether model compounds, 3-methylthiopropylamide (TPAM), thiomorpholine amide (TMAM), and 4-(methylthio)benzylamide (TPhAM) to investigate the effect of the chemical structures of the thioethers on the oxidation by hydrogen peroxide (H2O2). TPAM shows the fastest oxidation, followed by TMAM and TPhAM, showing that the oxidation reaction of thioethers can be modulated by changing the substituent groups bound to the sulfur atom. We next prepared micelles containing these different thioether groups within the core (TP, TM, and TPh micelles). The micelles containing the thioether groups with a higher oxidation sensitivity were destabilized by H2O2 at a lower concentration. Micelle destabilization was also tested in human liver cancer (HepG2) cells and human umbilical vein endothelial cells (HUVECs). The TP micelles having the highest oxidation sensitivity were destabilized in both HepG2 cells and HUVECs, while the TPh micelles, which showed the lowest reactivity toward H2O2, were stable in these cell lines. The TM micelles possessing a moderate oxidation sensitivity were destabilized in HepG2 cells but were stable in HUVECs. Furthermore, the micelles were loaded with doxorubicin (Dox) to evaluate their potential in drug delivery applications. Among the micelles, the TM micelles loaded with Dox showed the enhanced relative toxicity in HepG2 cells over HUVECs. Therefore, our approach to fine-tune the oxidation sensitivity of the micelles has potential for improving therapeutic efficacy and safety of drugs in cancer treatment.

Upper and Apparent Lower Critical Solution Temperature Branches in the Phase Diagram of Polymer:Small Molecule Semiconducting Systems.

Solution-processable semiconducting materials are complex materials with a wide range of applications. Despite their extensive study and utility, their molecular interactions as manifested, for example, in phase behavior are poorly understood. Here, we aim to understand the phase behavior of conjugated systems by determining phase diagrams spanning extensive temperature ranges for various combinations of the highly disordered semiconducting polymer (PTB7-Th) with crystallizable (IT-M and PC61BM) and noncrystallizable (di-PDI) small molecule acceptors (SMAs), with polystyrene as an amorphous control, a nonsemiconducting commodity polymer. We discover that the apparent binodal of the studied blends frequently consists of an upper critical solution temperature (UCST) and lower critical solution temperature (LCST) branch, exhibiting a sharp kink where the branches join. Our work suggests that phase diagrams might be a probe in combination with sophisticated models to understand the complexity of semiconducting materials, including microstructure and molecular interactions.

A molecular interaction-diffusion framework for predicting organic solar cell stability.

Rapid increase in the power conversion efficiency of organic solar cells (OSCs) has been achieved with the development of non-fullerene small-molecule acceptors (NF-SMAs). Although the morphological stability of these NF-SMA devices critically affects their intrinsic lifetime, their fundamental intermolecular interactions and how they govern property-function relations and morphological stability of OSCs remain elusive. Here, we discover that the diffusion of an NF-SMA into the donor polymer exhibits Arrhenius behaviour and that the activation energy Ea scales linearly with the enthalpic interaction parameters χH between the polymer and the NF-SMA. Consequently, the thermodynamically most unstable, hypo-miscible systems (high χ) are the most kinetically stabilized. We relate the differences in Ea to measured and selectively simulated molecular self-interaction properties of the constituent materials and develop quantitative property-function relations that link thermal and mechanical characteristics of the NF-SMA and polymer to predict relative diffusion properties and thus morphological stability.

The Role of Demixing and Crystallization Kinetics on the Stability of Non-Fullerene Organic Solar Cells.

With power conversion efficiency now over 17%, a long operational lifetime is essential for the successful application of organic solar cells. However, most non-fullerene acceptors can crystallize and destroy devices, yet the fundamental underlying thermodynamic and kinetic aspects of acceptor crystallization have received limited attention. Here, room-temperature (RT) diffusion coefficients of 3.4 × 10-23 and 2.0 × 10-22 are measured for ITIC-2Cl and ITIC-2F, two state-of-the-art non-fullerene acceptors. The low coefficients are enough to provide for kinetic stabilization of the morphology against demixing at RT. Additionally profound differences in crystallization characteristics are discovered between ITIC-2F and ITIC-2Cl. The differences as observed by secondary-ion mass spectrometry, differential scanning calorimetry (DSC), grazing-incidence wide-angle X-ray scattering, and microscopy can be related directly to device degradation and are attributed to the significantly different nucleation and growth rates, with a difference in the growth rate of a factor of 12 at RT. ITIC-4F and ITIC-4Cl exhibit similar characteristics. The results reveal the importance of diffusion coefficients and melting enthalpies in controlling the growth rates, and that differences in halogenation can drastically change crystallization kinetics and device stability. It is furthermore delineated how low nucleation density and large growth rates can be inferred from DSC and microscopy experiments which could be used to guide molecular design for stability.

The Critical Role of Materials' Interaction in Realizing Organic Field-Effect Transistors Via High-Dilution Blending with Insulating Polymers.

High-performance low-band-gap polymer semiconductors are visibly colored, making them unsuitable for transparent and imperceptible electronics without reducing film thickness to the nanoscale range. Herein, we demonstrate polymer/insulator blends exhibiting favorable miscibility that improves the transparency and carrier transport in an organic field-effect transistor (OFET) device. The mesoscale structures leading to more efficient charge transport in ultrathin films relevant to the realization of transparent and flexible electronic applications are explored based on thermodynamic material interaction principles in conjunction with optical and morphological studies. By blending the commodity polymer polystyrene (PS) with two high-performing polymers, PDPP3T and P (NDI2OD-T2) (known as N2200), a drastic difference in morphology and fiber network are observed due to considerable differences in the degree of thermodynamic interaction between the conjugated polymers and PS. Intrinsic material interaction behavior establishes a long-range intermolecular interaction in the PDPP3T polymer fibrillar network dispersed in the majority (80%) PS matrix resulting in a ca. 3-fold increased transistor hole mobility of 1.15 cm2 V-1 s-1 (highest = 1.5 cm2 V-1 s-1) as compared to the pristine material, while PS barely affects the electron mobility in N2200. These basic findings provide important guidelines to achieve high mobility in transparent OFETs.

Highly Efficient, Stable, and Ductile Ternary Nonfullerene Organic Solar Cells from a Two-Donor Polymer Blend.

Organic solar cells (OSCs) are one of the most promising cost-effective options for utilizing solar energy, and, while the field of OSCs has progressed rapidly in device performance in the past few years, the stability of nonfullerene OSCs has received less attention. Developing devices with both high performance and long-term stability remains challenging, particularly if the material choice is restricted by roll-to-roll and benign solvent processing requirements and desirable mechanical durability. Building upon the ink (toluene:FTAZ:IT-M) that broke the 10% benchmark when blade-coated in air, a second donor material (PBDB-T) is introduced to stabilize and enhance performance with power conversion efficiency over 13% while keeping toluene as the solvent. More importantly, the ternary OSCs exhibit excellent thermal stability and storage stability while retaining high ductility. The excellent performance and stability are mainly attributed to the inhibition of the crystallization of nonfullerene small-molecular acceptors (SMAs) by introducing a stiff donor that also shows low miscibility with the nonfullerene SMA and a slightly higher highest occupied molecular orbital (HOMO) than the host polymer. The study indicates that improved stability and performance can be achieved in a synergistic way without significant embrittlement, which will accelerate the future development and application of nonfullerene OSCs.

Use of cerium oxide nanoparticles: a good candidate to improve skin tissue engineering.

Today advancements in nanotechnology have made extensive progress in tissue engineering. Application of cerium oxide nanoparticles (CeO2) has improved regenerative medicine due to their antioxidant properties. In this study, nanoparticles were used to increase the efficacy of skin substitutes. Human skin samples were decellularized using four methods and studied via histological stainings and DNA content analyses. Then CeO2 dispersing and its stability were investigated. The prepared acellular dermal matrices (ADMs) were immersed in CeO2 suspension and their effects were evaluated on growth of cultured human adipose derived-mesenchymal stem cells (hAd-MSCs) using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and histological methods. Moreover, their antioxidant properties were assessed based on DPPH degradation. Changes in the collagen contents of the scaffolds containing cells and CeO2 were also determined by electron microscopy and their tensile strength was compared to ADM. Our results indicated that use of trypsin/NaOH protocol resulted in most efficient cell removal while maintaining extracellular matrix (ECM) architecture. Among different dispersal methods, the approach using Dulbecco's modified Eagle's medium (DMEM), wetting with fetal bovine serum (FBS) and ultrasonic bath resulted in the best stability. Furthermore, it was shown that CeO2 not only had no toxicity on the cells, but also increased the growth and survival of hAd-MSCs by about 27%, improved free radical scavenging, as well as the amount of collagen and tensile strength of the scaffolds containing nanoparticles compared to the ADM. It can be concluded that the combination of ADM/CeO2/hAd-MSCs could be a step forward in skin tissue engineering.

Quantitative relations between interaction parameter, miscibility and function in organic solar cells.

Although it is known that molecular interactions govern morphology formation and purity of mixed domains of conjugated polymer donors and small-molecule acceptors, and thus largely control the achievable performance of organic solar cells, quantifying interaction-function relations has remained elusive. Here, we first determine the temperature-dependent effective amorphous-amorphous interaction parameter, χaa(T), by mapping out the phase diagram of a model amorphous polymer:fullerene material system. We then establish a quantitative 'constant-kink-saturation' relation between χaa and the fill factor in organic solar cells that is verified in detail in a model system and delineated across numerous high- and low-performing materials systems, including fullerene and non-fullerene acceptors. Our experimental and computational data reveal that a high fill factor is obtained only when χaa is large enough to lead to strong phase separation. Our work outlines a basis for using various miscibility tests and future simulation methods that will significantly reduce or eliminate trial-and-error approaches to material synthesis and device fabrication of functional semiconducting blends and organic blends in general.

Competition between exceptionally long-range alkyl sidechain ordering and backbone ordering in semiconducting polymers and its impact on electronic and optoelectronic properties.

Intra- and intermolecular ordering greatly impact the electronic and optoelectronic properties of semiconducting polymers. Despite much prior efforts regarding molecular packing, the interrelationship between ordering of alkyl sidechains and conjugated backbones has not been fully detailed. We report here the discovery of a highly ordered alkyl sidechain phase in six representative semiconducting polymers, determined from distinct spectroscopic and diffraction signatures. The sidechain ordering exhibits unusually large coherence lengths of at least 70 nm, induces torsional/twisting backbone disorder, and results in a vertically layered multilayer nanostructure with ordered sidechain layers alternating with disordered backbone layers. Calorimetry and in-situ variable temperature scattering measurements in a model system PBnDT-FTAZ clearly delineate this competition of ordering that prevents the simultaneous long-range order of both moieties. The long-range sidechain ordering can be exploited as a transient state to fabricate PBnDT-FTAZ films with an atypical edge-on texture and 2.5x improved OFET mobility. The observed influence of ordering between the moieties implies that improved molecular design could produce synergistic rather than destructive ordering effects. Given the large sidechain coherence lengths observed, such synergistic ordering should greatly improve the coherence length of backbone ordering and thereby improve electronic and optoelectronic properties such as charge transport and exciton diffusion lengths.

9.73% Efficiency Nonfullerene All Organic Small Molecule Solar Cells with Absorption-Complementary Donor and Acceptor.

In the last two years, polymer solar cells (PSCs) developed quickly with n-type organic semiconductor (n-OSs) as acceptor. In contrast, the research progress of nonfullerene organic solar cells (OSCs) with organic small molecule as donor and the n-OS as acceptor lags behind. Here, we synthesized a D-A structured medium bandgap organic small molecule H11 with bithienyl-benzodithiophene (BDTT) as central donor unit and fluorobenzotriazole as acceptor unit, and achieved a power conversion efficiency (PCE) of 9.73% for the all organic small molecules OSCs with H11 as donor and a low bandgap n-OS IDIC as acceptor. A control molecule H12 without thiophene conjugated side chains on the BDT unit was also synthesized for investigating the effect of the thiophene conjugated side chains on the photovoltaic performance of the p-type organic semiconductors (p-OSs). Compared with H12, the 2D-conjugated H11 with thiophene conjugated side chains shows intense absorption, low-lying HOMO energy level, higher hole mobility and ordered bimodal crystallite packing in the blend films. Moreover, a larger interaction parameter (χ) was observed in the H11 blends calculated from Hansen solubility parameters and differential scanning calorimetry measurements. These special features combined with the complementary absorption of H11 donor and IDIC acceptor resulted in the best PCE of 9.73% for nonfullerene all small molecule OSCs up to date. Our results indicate that fluorobenzotriazole based 2D conjugated p-OSs are promising medium bandgap donors in the nonfullerene OSCs.

Panchromatic Sequentially Cast Ternary Polymer Solar Cells.

A sequential-casting ternary method is developed to create stratified bulk heterojunction (BHJ) solar cells, in which the two BHJ layers are spin cast sequentially without the need of adopting a middle electrode and orthogonal solvents. This method is found to be particularly useful for polymers that form a mechanically alloyed morphology due to the high degree of miscibility in the blend.

Does drill-induced noise have an impact on sensorineural hearing during craniotomy procedure?

OBJECTIVE: It is well known that exposure to noise can lead to hearing loss. Craniotomy drills have significant noise and vibration. Since a noise induced by the drill during craniotomy is thought to be one of the causes, we examined its effect on the sensorineural hearing in this study. METHODS: Thirty-nine patients who had undergone craniotomy operations served as the basis for this study between Jul. 2007 and Dec. 2008. Standard pure-tone audiometry (PTA) and speech recognition thresholds (SRT) were calculated for all subjects before, one week and 1 year after craniotomy. RESULTS: Statistically significant differences were not observed at the lower and middle frequencies (0.25-2 kHz), however, differences in the hearing thresholds at higher frequencies (4-6 kHz) were statistically significant before and after craniotomy. Mean pure-tone thresholds obtained was significantly more in older subjects when compared to young patients. Moreover, the correlation between increased number of burr holes and sensorineural hearing loss (SNHL) was statistically significant. CONCLUSIONS: We conclude that drill-generated noise during craniotomy has been incriminated as a cause of SNHL. Possible noise disturbance to the inner ear can only be avoided by minimizing the number of burr holes and the duration of harmful noise exposure to the cochlear structures.

Pulmonary artery stenosis shortly after lung transplantation: successful balloon dilation and stent insertion in one case.

BACKGROUND: Pulmonary artery stenosis after lung transplantation is a rare complication. It usually requires surgical correction but even after that the outcome is not favorable.
CASE REPORT: The patient was a 53-years-old woman who was candidate for lung transplantation surgery due to pulmonary fibrosis. After 7 months on waiting list, with severe limitations in daily living activities, she received a single lung transplant in 2007. The surgery was performed without any complication. One day after surgery and after extubation, the patient needed oxygen supplementation through mask with reservoir bag. In bronchoscopy, black-and-white exudate and black membrane that blocked the main bronchus in the transplanted lung was observed. By bronchial lavage the membrane and exudate were successfully removed and patient received antibiotics for documented Aspergillus infection and methylprednisolone pulse therapy for evidences of graft rejection. Despite success in treatments of the mentioned complications, the condition of the patient deteriorated and she became totally dependent to supplemental oxygen. Oxygen consumption level had increase and pulmonary artery pressure was increasing gradually. With suspicion to pulmonary artery stenosis, bronchial CT-Scan with contrast was performed 13 days after transplantation surgery which showed a 50% stenosis. Trans-esophageal echocardiography also showed a stenosis with 40 mmHg gradient. 18 days after transplantation surgery, percutaneous balloon angioplasty was performed which was initially successful but re-stenosis occurred. Seven days later, another balloon angioplasty with stent insertion was performed. After the procedure, the gradient has been removed. Patient was discharged 30 days after transplantation. Follow-up after 10 months revealed no stenosis and the stent was working properly.
CONCLUSIONS: Stent angioplasty can be performed with no problem or complication if pulmonary artery stenosis is seen after lung transplantation.