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1.
JACS Au ; 4(3): 919-929, 2024 Mar 25.
Artigo em Inglês | MEDLINE | ID: mdl-38559709

RESUMO

Solvation and ion valency effects on selectivity of metal oxyanions at redox-polymer interfaces are explored through in situ spatial-temporally resolved neutron reflectometry combined with large scale ab initio molecular dynamics. The selectivity of ReO4- vs MoO42- for two redox-metallopolymers, poly(vinyl ferrocene) (PVFc) and poly(3-ferrocenylpropyl methacrylamide) (PFPMAm) is evaluated. PVFc has a higher Re/Mo separation factor compared to PFPMAm at 0.6 V vs Ag/AgCl. In situ techniques show that both PVFc and PFPMAm swell in the presence of ReO4- (having higher solvation with PFPMAm), but do not swell in contact with MoO42-. Ab initio molecular simulations suggest that MoO42- maintains a well-defined double solvation shell compared to ReO4-. The more loosely solvated anion (ReO4-) is preferably adsorbed by the more hydrophobic redox polymer (PVFc), and electrostatic cross-linking driven by divalent anionic interactions could impair film swelling. Thus, the in-depth understanding of selectivity mechanisms can accelerate the design of ion-selective redox-mediated separation systems for transition metal recovery and recycling.

2.
Materials (Basel) ; 17(3)2024 Jan 24.
Artigo em Inglês | MEDLINE | ID: mdl-38591400

RESUMO

This paper introduces a method for high-resolution lattice image reconstruction and dislocation analysis based on diffraction extinction. The approach primarily involves locating extinction spots in the Fourier transform spectrum (reciprocal space) and constructing corresponding diffraction wave functions. By the coherent combination of diffraction and transmission waves, the lattice image of the extinction planes is reconstructed. This lattice image is then used for dislocation localization, enabling the observation and analysis of crystal planes that exhibit electron diffraction extinction effects and atomic jump arrangements during high-resolution transmission electron microscopy (HRTEM) characterization. Furthermore, due to the method's effectiveness in localizing dislocations, it offers a unique advantage when analyzing high-resolution images with relatively poor quality. The feasibility of this method is theoretically demonstrated in this paper. Additionally, the method was successfully applied to observed edge dislocations, such as 1/6[211-], 1/6[2-11-], and 1/2[01-1], which are not easily observable in conventional HRTEM characterization processes, in electro-deposited Cu thin films. The Burgers vectors were determined. Moreover, this paper also attempted to observe screw dislocations that are challenging to observe in high-resolution transmission electron microscopy. By shifting a pair of diffraction extinction spots and superimposing the reconstructed images before and after the shift, screw dislocations with a Burgers vector of 1/2[011-] were successfully observed in electro-deposited Cu thin films.

3.
J Orthop Surg (Hong Kong) ; 32(1): 10225536241248707, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38636168

RESUMO

PURPOSE: To investigate the diagnostic value of anti-Mullerian hormone (AMH) and Inhibin B (InhB) in menopausal women with osteoporosis from the Chinese Daur ethnic group. METHODS: A total of 175 menopausal women were selected and divided into the osteoporosis group (N = 90) and the control group (N = 85). BMD was measured by dual-energy X-ray absorptiometry, and laboratory indicators of osteoporosis, for example, serum osteocalcin (OC), ß-collagen special sequence (ß-CTX), and procollagen type I amino-terminal propeptide (PINP), bone alkaline phosphatase (BALP), AMH, and InhB were measured by commercial kits. The relationship between osteoporosis and AMH or InhB was analyzed. The predictive values of AMH and InhB were reflected by the ROC curve and logistic regression. RESULTS: The level of BMD was decreased and the levels of OC, ß-CTX, PINP, and BALP of the menopausal osteoporosis group were increased. The concentration of AMH and InhB in the menopausal osteoporosis group was decreased and they had connections with each other. AMH and InhB could be used as independent indicators for the occurrence of osteoporosis in menopausal women and their combination had a higher diagnostic value. CONCLUSION: AMH and InhB measurements in menopausal women had a certain clinical significance in the detection of osteoporosis. The occurrence of osteoporosis was related to BMD, OC, ß-CTX, BALP, AMH, and InhB.


Assuntos
Osteoporose Pós-Menopausa , Osteoporose , Humanos , Feminino , Hormônio Antimülleriano , Etnicidade , Inibinas , Menopausa , Fosfatase Alcalina , Osteocalcina , China , Biomarcadores
4.
Opt Express ; 32(6): 10230-10240, 2024 Mar 11.
Artigo em Inglês | MEDLINE | ID: mdl-38571239

RESUMO

A four-channel ultrawideband photodetector (PD) module with a size of 26.1 mm ×33.2 mm × 8.5 mm has been demonstrated in our laboratory. We propose a method to improve the bandwidth of the PD module based on compensating parasitic parameters by dual resistance regulation on the P and N terminals of the PD chip. A small signal equivalent circuit model with package matching network is established for the PD module, and the effectiveness of the proposed method and the accuracy of the model are verified by experiments. A four-channel photodetector module with a -3 dB bandwidth of up to 67 GHz is fabricated by using photodetector chips with -3 dB bandwidths of 46 GHz, and the responsivity is up to 0.50A/W.

5.
J Phys Chem Lett ; 15(16): 4444-4450, 2024 Apr 25.
Artigo em Inglês | MEDLINE | ID: mdl-38626466

RESUMO

Neutron reflectometry has long been a powerful tool to study the interfacial properties of energy materials. Recently, time-resolved neutron reflectometry has been used to better understand transient phenomena in electrochemical systems. Those measurements often comprise a large number of reflectivity curves acquired over a narrow q range, with each individual curve having lower information content compared to a typical steady-state measurement. In this work, we present an approach that leverages existing reinforcement learning tools to model time-resolved data to extract the time evolution of structure parameters. By mapping the reflectivity curves taken at different times as individual states, we use the Soft Actor-Critic algorithm to optimize the time series of structure parameters that best represent the evolution of an electrochemical system. We show that this approach constitutes an elegant solution to the modeling of time-resolved neutron reflectometry data.

6.
Nanomaterials (Basel) ; 14(7)2024 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-38607154

RESUMO

Topological Weyl semimetals are characterized by open Fermi arcs on their terminal surfaces, these materials not only changed accepted concepts of the Fermi loop but also enabled many exotic phenomena, such as one-way propagation. The key prerequisite is that the two terminal surfaces have to be well separated, i.e., the Fermi arcs are not allowed to couple with each other. Thus, their interaction was overlooked before. Here, we consider coupled Fermi arcs and propose a Weyl planar waveguide, wherein we found a saddle-chips-like hybridized guiding mode. The hybridized modes consist of three components: surface waves from the top and bottom surfaces and bulk modes inside the Weyl semimetal. The contribution of these three components to the hybridized mode appears to be z-position-dependent rather than uniform. Beyond the conventional waveguide framework, those non-trivial surface states, with their arc-type band structures, exhibit strong selectivity in propagation direction, providing an excellent platform for waveguides. Compared with the conventional waveguide, the propagation direction of hybridized modes exhibits high z-position-dependency. For example, when the probe plane shifts from the top interface to the bottom interface, the component propagating horizontally becomes dimmer, while the component propagating vertically becomes brighter. Experimentally, we drilled periodic holes in metal plates to sandwich an ideal Weyl meta-crystal and characterize the topological guiding mode. Our study shows the intriguing behaviors of topological photonic waveguides, which could lead to beam manipulation, position sensing, and even 3D information processing on photonic chip. The Weyl waveguide also provides a platform for studying the coupling and the interaction between surface and bulk states.

7.
Cancer Med ; 13(8): e7208, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38659399

RESUMO

OBJECTIVE: To elucidate the potential benefits of combining radiotherapy and epidermal growth factor receptor-tyrosine kinase inhibitors (EGFR-TKIs) for individuals with Stage IV lung adenocarcinoma (LUAD) harboring either exon 19 deletion (19-Del) or exon 21 L858R mutation (21-L858R). METHODS: In this real-world retrospective study, 177 individuals with Stage IV LUAD who underwent EGFR-TKIs and radiotherapy at Shandong Cancer Hospital from June 2012 to August 2017 were included. The main focus of this real-world study was overall survival (OS). RESULTS: The clinical characteristics of patients with Stage IV LUAD harboring 19-Del were similar to those harboring 21-L858R (p > 0.05). Overall, the patients had a median OS (mOS) of 32.0 months (95% confidence interval [CI]: 28.6-35.5). Subsequently, multivariate analysis indicated that both EGFR mutations and thoracic radiotherapy were independent predictors of OS (p = 0.001 and 0.013). Furthermore, subgroup analysis highlighted a longer OS for the 19-Del group compared to the 21-L858R group, especially when EGFR-TKIs were combined with bone metastasis or thoracic radiotherapy (mOS: 34.7 vs. 25.1 months and 51.0 vs. 29.6 months; p = 0.0056 and 0.0013, respectively). However, no significant differences were found in OS when considering patients who underwent brain metastasis radiotherapy (mOS: 34.7 vs. 25.1 months; p = 0.088). CONCLUSIONS: Patients with Stage IV LUAD harboring 19-Del experience a notably prolonged OS following combined therapy with EGFR-TKIs and radiotherapy, while this OS benefit is observed despite the absence of substantial differences in the clinical characteristics between the 19-Del and 21-L858R groups.


Assuntos
Adenocarcinoma de Pulmão , Receptores ErbB , Neoplasias Pulmonares , Mutação , Estadiamento de Neoplasias , Inibidores de Proteínas Quinases , Humanos , Masculino , Feminino , Receptores ErbB/genética , Receptores ErbB/antagonistas & inibidores , Pessoa de Meia-Idade , Inibidores de Proteínas Quinases/uso terapêutico , Adenocarcinoma de Pulmão/genética , Adenocarcinoma de Pulmão/patologia , Adenocarcinoma de Pulmão/terapia , Adenocarcinoma de Pulmão/tratamento farmacológico , Adenocarcinoma de Pulmão/radioterapia , Adenocarcinoma de Pulmão/mortalidade , Estudos Retrospectivos , Neoplasias Pulmonares/genética , Neoplasias Pulmonares/patologia , Neoplasias Pulmonares/terapia , Neoplasias Pulmonares/tratamento farmacológico , Neoplasias Pulmonares/radioterapia , Neoplasias Pulmonares/mortalidade , Idoso , Prognóstico , Adulto , Éxons , Quimiorradioterapia/métodos , Deleção de Sequência
8.
J Pharm Pharmacol ; 2024 Mar 26.
Artigo em Inglês | MEDLINE | ID: mdl-38530642

RESUMO

OBJECTIVES: Several studies have shown that propofol administration during surgery effectively attenuates remifentanil-induced hyperalgesia (RIH). Ciprofol, a novel intravenous sedative agent analogous to propofol, has not yet been proven efficacious in alleviating RIH. The present study aimed to investigate the effect of ciprofol on RIH and the possible mechanisms involved. METHODS: The RIH model was established by an infusion of remifentanil (1 µg·kg-1·min-1) 60 min in rats with incisional pain. Ciprofol (0.1, 0.25, and 0.4 mg·kg-1·min-1) was simultaneously infused to evaluate its effect on RIH. The antinociception of ciprofol was verified by measured paw withdrawal mechanical threshold (PWMT) and paw withdrawal thermal latency (PWTL). γ-aminobutyric acid type A receptor α2 subunit (α2GABAAR), N-methyl-d-aspartate receptor NR2B subunit (NR2B), calcium/calmodulin-dependent protein kinase II α (CaMKIIα), and phosphorylated CaMKIIα (P-CaMKIIα) in the spinal cord and hippocampus of rats were assessed by western blotting and immunohistochemistry. KEY FINDINGS: The results showed that ciprofol dose-dependently increased PWMT and PWTL values in RIH rats. Moreover, ciprofol upregulated α2GABAAR and downregulated NR2B and P-CaMKIIα in the rat spinal cord and hippocampus. CONCLUSIONS: Ciprofol alleviates RIH effectively, and the anti-hyperalgesic mechanisms may involve increasing α2GABAAR levels and decreasing NR2B and P-CaMKIIα levels in the spinal cord and hippocampus.

9.
Sci Bull (Beijing) ; 2024 Mar 20.
Artigo em Inglês | MEDLINE | ID: mdl-38553347

RESUMO

,、、、、。,。,TPD-L1。PD-L1,T。T,T,PD-L1。。.

10.
J Virol Methods ; 327: 114921, 2024 Mar 28.
Artigo em Inglês | MEDLINE | ID: mdl-38552881

RESUMO

Dendritic cells (DCs) play a pivotal role in maintaining immune tolerance. Using recombinant adenovirus (rAd) to deliver vectors to immature dendritic cells (imDCs) is an important method for studying the tolerogenic function of DCs. We found that using RPMI medium and a higher MOI during transduction increased the expression of CD80, CD86, and MHC-II on the surface of imDCs. Our data reveal a significant increase in the secretion of the pro-inflammatory cytokine IL-6 in the group showing the most pronounced phenotypic changes. In the mouse heart transplant model, imDCs with unstable phenotype and function due to adenoviral transduction resulted in an increased proportion of Th1 and Th17 cells in recipients. However, these effects can be managed, and our proposed optimized transduction strategy significantly minimizes these adverse effects. Our study holds significant implications for the development and optimization of immunotherapy utilizing tolerogenic dendritic cells.

11.
Angew Chem Int Ed Engl ; : e202402950, 2024 Mar 21.
Artigo em Inglês | MEDLINE | ID: mdl-38512110

RESUMO

The electrochemical synthesis of ethylene oxide (EO) using ethylene and water under ambient conditions presents a low-carbon alternative to existing industrial production process. Yet, the electrocatalytic ethylene epoxidation route is currently hindered by largely insufficient activity, EO selectivity, and long-term stability. Here we report a single atom Ru-doped hollandite structure KIr4O8 (KIrRuO) nanowire catalyst for efficient EO production via a chloride-mediated ethylene epoxidation process. The KIrRuO catalyst exhibits an EO partial current density up to 0.7 A cm-2 and an EO yield as high as 92.0 %. The impressive electrocatalytic performance towards ethylene epoxidation is ascribed to the modulation of electronic structures of adjacent Ir sites by single Ru atoms, which stabilizes the *CH2CH2OH intermediate and facilitates the formation of active Cl2 species during the generation of 2-chloroethanol, the precursor of EO. This work provides a single atom modulation strategy for improving the reactivity of adjacent metal sites in heterogeneous electrocatalysts.

13.
Front Microbiol ; 15: 1364425, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38450166

RESUMO

Engineering Saccharomyces cerevisiae for biodegradation and transformation of industrial toxic substances such as catechol (CA) has received widespread attention, but the low tolerance of S. cerevisiae to CA has limited its development. The exploration and modification of genes or pathways related to CA tolerance in S. cerevisiae is an effective way to further improve the utilization efficiency of CA. This study identified 36 genes associated with CA tolerance in S. cerevisiae through genome-wide identification and bioinformatics analysis and the ERG6 knockout strain (ERG6Δ) is the most sensitive to CA. Based on the omics analysis of ERG6Δ under CA stress, it was found that ERG6 knockout affects pathways such as intrinsic component of membrane and pentose phosphate pathway. In addition, the study revealed that 29 genes related to the cell wall-membrane system were up-regulated by more than twice, NADPH and NADP+ were increased by 2.48 and 4.41 times respectively, and spermidine and spermine were increased by 2.85 and 2.14 times, respectively, in ERG6Δ. Overall, the response of cell wall-membrane system, the accumulation of spermidine and NADPH, as well as the increased levels of metabolites in pentose phosphate pathway are important findings in improving the CA resistance. This study provides a theoretical basis for improving the tolerance of strains to CA and reducing the damage caused by CA to the ecological environment and human health.

14.
Nat Commun ; 15(1): 2440, 2024 Mar 18.
Artigo em Inglês | MEDLINE | ID: mdl-38499579

RESUMO

As a milestone in the exploration of topological physics, Fermi arcs bridging Weyl points have been extensively studied. Weyl points, as are Fermi arcs, are believed to be only stable when preserving translation symmetry. However, no experimental observation of aperiodic Fermi arcs has been reported so far. Here, we continuously twist a bi-block Weyl meta-crystal and experimentally observe the twisted Fermi arc reconstruction. Although both the Weyl meta-crystals individually preserve translational symmetry, continuous twisting operation leads to the aperiodic hybridization and scattering of Fermi arcs on the interface, which is found to be determined by the singular total reflection around Weyl points. Our work unveils the aperiodic scattering of Fermi arcs and opens the door to continuously manipulating Fermi arcs.

15.
Clin Med (Lond) ; 24(1): 100006, 2024 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-38354621

RESUMO

We conducted a service evaluation of the medical support worker (MSW) role at Oxford University Hospitals NHS Foundation Trust following the Coronavirus 2019 (COVID-19) pandemic. The aim was to explore the roles of MSWs, their contributions to the NHS, factors influencing their career choices, and the goals of the MSW position, to inform quality improvement in relation to their integration into the Trust. The perspectives of MSWs, their supervisors and recruiters were analysed through nine semi-structured interviews and two focus group discussions involving 18 participants. Results were categorised into micro-, meso-, and macro-levels of the health system. At the micro-level, MSWs were recognised as a diverse group of highly qualified international medical graduates (IMGs) who had a crucial role during the pandemic. At the meso-level, participants emphasised the importance of a comprehensive induction by the hospital, to clarify responsibilities and familiarise MSWs with the health system. At the macro-level, the role facilitated MSW integration within the NHS, with the aim of practising as doctors. The importance of comprehensive hospital induction, with role clarity for both MSWs and their teams, supportive supervision and assistance with applying for registration with the General Medical Council, were highlighted as key quality improvement areas.


Assuntos
COVID-19 , Pandemias , Humanos , Hospitais Universitários , Medicina Estatal , Reino Unido/epidemiologia
16.
Front Endocrinol (Lausanne) ; 15: 1293842, 2024.
Artigo em Inglês | MEDLINE | ID: mdl-38370351

RESUMO

Background: Non-invasive prognostic predictors for rare pancreatic neuroendocrine tumors (PNETs) are lacking. We aimed to approach the prognostic value of preoperative systemic inflammatory markers in patients with PNETs. Methods: The clinical data of 174 patients with PNETs undergoing surgical treatment were retrospectively analyzed to explore the correlation of neutrophil to lymphocyte ratio (NLR), platelet to lymphocyte ratio (PLR), lymphocyte to monocyte ratio (LMR), and platelet to white blood cell ratio (PWR) with clinicopathological parameters and the progression of tumor after the operation. The optimal cutoff values for predictors and the area under the curve (AUC) of the receiver operating characteristic (ROC) were estimated. Univariate and multivariate Cox proportional hazards models were used to assess the relation between NLR, LMR, PLR, and progression-free survival (PFS), examined by the Kaplan-Meier and log-rank tests. Results: The scores of the NLR (P = 0.039) and PLR (P = 0.011) in the progression group were significantly higher than those in the progression-free group, and the LMR was significantly lower than those in the progression-free group (P = 0.001). The best cutoff values of NLR, LMR, and PLR before operation were 2.28, 4.36, and 120.91. The proportions of tumor progression in the high NLR group (P = 0.007) and high PLR group (P = 0.013) obviously increased, and the proportion of tumor development in the low LMR group was higher than that in the high LMR group (P < 0.001). The K-M survival curve showed that the progression-free survival rate was lower in the high NLR group (P = 0.004), the low LMR group (P < 0.001), and the high PLR group (P = 0.018). The results of the multivariate Cox proportional hazards model suggested that preoperative LMR (HR = 3.128, 95% CI: 1.107~8.836, P = 0.031) was an independent predictor of PFS. Conclusion: The markers of systemic inflammation, especially LMR, can predict the postoperative progression of PNETs.


Assuntos
Tumores Neuroectodérmicos Primitivos , Tumores Neuroendócrinos , Neoplasias Pancreáticas , Humanos , Estudos Retrospectivos , Tumores Neuroendócrinos/diagnóstico , Tumores Neuroendócrinos/cirurgia , Inflamação/diagnóstico , Neoplasias Pancreáticas/diagnóstico , Neoplasias Pancreáticas/cirurgia
17.
Phytomedicine ; 126: 155372, 2024 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-38382281

RESUMO

BACKGROUND: Renal fibrosis is a common pathway that drives the advancement of numerous kidney maladies towards end-stage kidney disease (ESKD). Suppressing renal fibrosis holds paramount clinical importance in forestalling or retarding the transition of chronic kidney diseases (CKD) to renal failure. Schisandrin A (Sch A) possesses renoprotective effect in acute kidney injury (AKI), but its effects on renal fibrosis and underlying mechanism(s) have not been studied. STUDY DESIGN: Serum biochemical analysis, histological staining, and expression levels of related proteins were used to assess the effect of PKCß knockdown on renal fibrosis progression. Untargeted metabolomics was used to assess the effect of PKCß knockdown on serum metabolites. Unilateral Ureteral Obstruction (UUO) model and TGF-ß induced HK-2 cells and NIH-3T3 cells were used to evaluate the effect of Schisandrin A (Sch A) on renal fibrosis. PKCß overexpressed NIH-3T3 cells were used to verify the possible mechanism of Sch A. RESULTS: PKCß was upregulated in the UUO model. Knockdown of PKCß mitigated the progression of renal fibrosis by ameliorating perturbations in serum metabolites and curbing oxidative stress. Sch A alleviated renal fibrosis by downregulating the expression of PKCß in kidney. Treatment with Sch A significantly attenuated the upregulated proteins levels of FN, COL-I, PKCß, Vimentin and α-SMA in UUO mice. Moreover, Sch A exhibited a beneficial impact on markers associated with oxidative stress, including MDA, SOD, and GSH-Px. Overexpression of PKCß was found to counteract the renoprotective efficacy of Sch A in vitro. CONCLUSION: Sch A alleviates renal fibrosis by inhibiting PKCß and attenuating oxidative stress.


Assuntos
Ciclo-Octanos , Nefropatias , Lignanas , Compostos Policíclicos , Obstrução Ureteral , Camundongos , Animais , Fator de Crescimento Transformador beta1/metabolismo , Nefropatias/tratamento farmacológico , Rim , Fibrose , Obstrução Ureteral/patologia , Estresse Oxidativo
18.
J Am Chem Soc ; 146(4): 2701-2710, 2024 Jan 31.
Artigo em Inglês | MEDLINE | ID: mdl-38291994

RESUMO

Macromolecular crowding is the usual condition of cells. The implications of the crowded cellular environment for protein stability and folding, protein-protein interactions, and intracellular transport drive a growing interest in quantifying the effects of crowding. While the properties of crowded solutions have been extensively studied, less attention has been paid to the interaction of crowders with the cellular boundaries, i.e., membranes. However, membranes are key components of cells and most subcellular organelles, playing a central role in regulating protein channel and receptor functions by recruiting and binding charged and neutral solutes. While membrane interactions with charged solutes are dominated by electrostatic forces, here we show that significant charge-induced forces also exist between membranes and neutral solutes. Using neutron reflectometry measurements and molecular dynamics simulations of poly(ethylene glycol) (PEG) polymers of different molecular weights near charged and neutral membranes, we demonstrate the roles of surface dielectrophoresis and counterion pressure in repelling PEG from charged membrane surfaces. The resulting depletion zone is expected to have consequences for drug design and delivery, the activity of proteins near membrane surfaces, and the transport of small molecules along the membrane surface.


Assuntos
Polímeros , Proteínas , Membrana Celular , Polímeros/química , Proteínas/química , Polietilenoglicóis/química , Soluções/química
19.
Soft Matter ; 20(7): 1554-1564, 2024 Feb 14.
Artigo em Inglês | MEDLINE | ID: mdl-38270211

RESUMO

Bottlebrush random copolymers (BRCPs), consisting of a random distribution of two homopolymer chains along a backbone, can segregate to the interface between two immiscible homopolymers. BRCPs undergo a reconfiguration, where each block segregates to one of the homopolymer phases, adopting a Janus-type structure, reducing the interfacial tension and promoting adhesion between the two homopolymers, thereby serving as a Janus bottlebrush copolymer (JBCP) compatibilizer. We synthesized a series of JBCPs by copolymerizing deuterated or hydrogenated polystyrene (DPS/PS) and poly(tert-butyl acrylate) (PtBA) macromonomers using ruthenium benzylidene-initiated ring-opening metathesis polymerization (ROMP). Subsequent acid-catalyzed hydrolysis converted the PtBA brushes to poly(acrylic acid) (PAA). The JBCPs were then placed at the interface between DPS/PS homopolymers and poly(2-vinyl pyridine) (P2VP) homopolymers, where the degree of polymerization of the backbone (NBB) and the grafting density (GD) of the JBCPs were varied. Neutron reflectivity (NR) was used to determine the interfacial width and segmental density distributions (including PS homopolymer, PS block, PAA block and P2VP homopolymer) across the polymer-polymer interface. Our findings indicate that the star-like JBCP with NBB = 6 produces the largest interfacial broadening. Increasing NBB to 100 (rod-like shape) and 250 (worm-like shape) reduced the interfacial broadening due to a decrease in the interactions between blocks and homopolymers by stretching of blocks. Decreasing the GD from 100% to 80% at NBB = 100 caused an increase the interfacial width, yet further decreasing the GD to 50% and 20% reduced the interfacial width, as 80% of GD may efficiently increase the flexibility of blocks and promote interactions between homopolymers, while maintaining relatively high number of blocks attached to one molecule. The interfacial conformation of JBCPs was further translated into compatibilization efficiency. Thin film morphology studies showed that only the lower NBB values (NBB = 6 and NBB = 24) and the 80% GD of NBB = 100 had bicontinuous morphologies, due to a sufficient binding energy that arrested phase separation, supported by mechanical testing using asymmetric double cantilever beam (ADCB) tests. These provide fundamental insights into the assembly behavior of JBCPs compatibilizers at homopolymer interfaces, opening strategies for the design of new BCP compatibilizers.

20.
Nat Commun ; 15(1): 755, 2024 Jan 25.
Artigo em Inglês | MEDLINE | ID: mdl-38272879

RESUMO

Knowledge of carbonate compounds under high pressure inside Earth is key to understanding the internal structure of the Earth, the deep carbon cycle and major geological events. Here we use first-principles simulations to calculate the structure and elasticity of CaC2O5-minerals with different symmetries under high pressure. Our calculations show that CaC2O5-minerals represent a group of low-density low-seismic-wave velocity mantle minerals. Changes in seismic wave velocity caused by the phase transformation of CaC2O5-Cc to CaC2O5-I[Formula: see text]2d (CaC2O5-C2-l) agree with wave velocity discontinuity at a depth of 660 km in the mantle transition zone. Moreover, when CaC2O5-Fdd2 transforms into CaC2O5-C2 under 70 GPa, its shear wave velocity decreases by 7.4%, and its density increases by 5.8%, which is consistent with the characteristics of large low-shear-velocity provinces (LLSVPs). Furthermore, the shear wave velocity of CaC2O5-I[Formula: see text]2d is very similar to that of cubic Ca-perovskite, which is one of the main constituents of the previously detected LLSVPs. Therefore, we propose that CaC2O5 and its high-pressure polymorphs may be a main component of LLSVPs.

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