Chirality Determination of Nanocrystals by Electron Crystallography.

Chirality is a common phenomenon in nature and plays an important role in the properties of matter. The rational synthesis of chiral compounds and exploration of their applications in various fields require an unambiguous determination of their handedness. However, in many cases, determinations of the chiral crystal structure and chiral morphology have been a challenging task due to the lack of proper characterization methods, especially for nanosized crystals. Therefore, it is crucial to develop novel and efficient characterization methods. Owing to the strong interactions between matter and electrons, electron crystallography has become a powerful tool for structural analysis of nanomaterials. In recent years, methods based on electron crystallography, such as high-resolution electron microscopy imaging and electron diffraction, have been developed to unravel the chirality of nanomaterials. This brings new opportunities to the design, synthesis, and applications of versatile chiral nanomaterials. In this perspective, we summarize the recent methodology developments and ongoing research of electron crystallography for chiral structure and morphology determination of nanocrystals, including inorganic and organic materials, as well as highlight the potential and further improvement of these methods in the future.

Designable Synthesis of Layered Silicates and Tunable Interlayer Expanded to Zeolites.

Layered zeolitic silicates and corresponding interlayer-expanded porous materials exhibit attractive application potential in wide fields. Nonetheless, designable synthesis and structure analysis of layered silicates remain challenging. Herein, two kinds of layered silicates are synthesized using different di-quaternary ammonium-type organic structure-directing agents (OSDAs). Their crystal structures are analyzed and verified by 3D electron diffraction (3D ED) and high-resolution TEM imaging. The suitable configurations of OSDA can lead to desirable interlayer states. Additionally, two new zeolite structures both with 12-membered ring (MR) channels intersected by 8 MR channels and larger interlayer spaces are constructed from layered silicate precursors by interlayer silylation. The new zeolitic material exhibits potential application in adsorption of organic pollution and catalytic reaction. This study is expected to develop versatile ways for the design and synthesis of layered silicates even zeolites and provide references in characterizing layered materials and zeolites as well.

Structural analysis of nanocrystals by pair distribution function combining electron diffraction with crystal tilting.

As an important characterization method, pair distribution function (PDF) has been extensively used in structural analysis of nanomaterials, providing key insights into the degree of crystallinity, atomic structure, local disorder etc. The collection of scattering signals with good statistics is necessary for a reliable structural analysis. However, current conventional electron diffraction experiments using PDF (ePDF) are limited in their ability to acquire continuous diffraction rings for large nanoparticles. Herein, a new method - tilt-ePDF - is proposed to improve the data quality and compatibility of ePDF by a combination of electron diffraction and specimen tilting. In the present work, a tilt-series of electron diffraction patterns was collected from gold nanoparticles with three different sizes and a standard sample polycrystalline aluminium film for ePDF analysis. The results show that tilt-ePDF can not only enhance the continuity of diffraction rings, but can also improve the signal-to-noise ratio in the high scattering angle range. As a result, compared with conventional ePDF data, tilt-ePDF data provide structure parameters with a better accuracy and lower residual factors in the refinement against the crystal structure. This method provides a new way of utilizing ePDF to obtain accurate local structure information from nanoparticles.

A Stable Extra-Large Pore and High-Silica Zeolite Derived from Ge-Rich Precursor.

A multidimensional extra-large pore zeolite with highly hydrothermal stability, denoted as -IRT-HS, has been developed successfully, starting from Ge-rich germanosilicate precursor hydrothermally directed by a small and commercially available piperidinium-type organic structure-directing agent (OSDA). -IRT-HS, with the supermicropores, is structurally analogues to 28-membered ring -IRT topology as confirmed by various spectroscopic techniques. And it is the high-silica (Si/Ge=58) zeolite with the largest pore size as well. Notably, using acid-washed as-made Ge-rich -IRT precursor as the silicon source is crucial to restore partially collapsed structure into a stable framework by OSDA-assisted recrystallization. The calcined -IRT-HS maintains a high crystallinity, even when stored in a humid environment for extended periods or directly exposed to water. Additionally, high silica Al-containing analogue is also readily synthesized, serving as an active solid-acid catalyst in 1,3,5-triisopropylbenzene cracking reaction, yielding an impressive initial conversion up to 76.1 % much higher than conventional large-pore Beta zeolite (30.4 %). This work will pave the way for the designed synthesis of targeted high-silica zeolites with stable and extra-large pore frameworks, mimicking the structures of existing Ge-rich counterparts.

Homologous cancer cell membrane-camouflaged nanoparticles target drug delivery and enhance the chemotherapy efficacy of hepatocellular carcinoma.

Hepatocellular carcinoma (HCC) is a common digestive tract malignancy that seriously threatens human life and health. Early HCC may be treated by intervention, surgery, and internal radiotherapy, while the choice for late HCC is primarily chemotherapy to prolong patient survival. Lenvatinib (LT) is a Food and Drug Administration (FDA)-approved frontline drug for the treatment of advanced liver cancer and has achieved excellent clinical efficacy. However, its poor solubility and severe side effects cannot be ignored. In this study, a bionic nanodrug delivery platform was successfully constructed. The platform consists of a core of Lenvatinib wrapped with a pH-sensitive polymer, namely, poly(ß-amino ester)-polyethylene glycol-amine (PAE-PEG-NH2), and a shell formed by a cancer cell membrane (CCM). The prepared nanodrugs have high drug loading capacity, long-term stability, good biocompatibility, and a long retention time. In addition, the targeting effect of tumor cell membranes and the pH-responsive characteristics of the polymer materials enable them to precisely target tumor cells and achieve responsive release in the tumor microenvironment, which makes them suitable for effective drug delivery. In vivo experiments revealed that the nanodrug showed superior tumor accumulation and therapeutic effects in subcutaneous tumor mice model and could effectively eliminate tumors within 21 days. As a result, it opens up a new way to reduce side effects and improve the specific therapeutic effect of first-line clinical medications to treat tumors.

Deep learning-based relapse prediction of neuromyelitis optica spectrum disorder with anti-aquaporin-4 antibody.

Objective: We previously identified the independent predictors of recurrent relapse in neuromyelitis optica spectrum disorder (NMOSD) with anti-aquaporin-4 antibody (AQP4-ab) and designed a nomogram to estimate the 1- and 2-year relapse-free probability, using the Cox proportional hazard (Cox-PH) model, assuming that the risk of relapse had a linear correlation with clinical variables. However, whether the linear assumption fits real disease tragedy is unknown. We aimed to employ deep learning and machine learning to develop a novel prediction model of relapse in patients with NMOSD and compare the performance with the conventional Cox-PH model. Methods: This retrospective cohort study included patients with NMOSD with AQP4-ab in 10 study centers. In this study, 1,135 treatment episodes from 358 patients in Huashan Hospital were employed as the training set while 213 treatment episodes from 92 patients in nine other research centers as the validation set. We compared five models with added variables of gender, AQP4-ab titer, previous attack under the same therapy, EDSS score at treatment initiation, maintenance therapy, age at treatment initiation, disease duration, the phenotype of the most recent attack, and annualized relapse rate (ARR) of the most recent year by concordance index (C-index): conventional Cox-PH, random survival forest (RSF), LogisticHazard, DeepHit, and DeepSurv. Results: When including all variables, RSF outperformed the C-index in the training set (0.739), followed by DeepHit (0.737), LogisticHazard (0.722), DeepSurv (0.698), and Cox-PH (0.679) models. As for the validation set, the C-index of LogisticHazard outperformed the other models (0.718), followed by DeepHit (0.704), DeepSurv (0.698), RSF (0.685), and Cox-PH (0.651) models. Maintenance therapy was calculated to be the most important variable for relapse prediction. Conclusion: This study confirmed the superiority of deep learning to design a prediction model of relapse in patients with AQP4-ab-positive NMOSD, with the LogisticHazard model showing the best predictive power in validation.

Neuromyelitis Optica Spectrum Disorder With Anti-Aquaporin-4 Antibody: Outcome Prediction Models.

Background: Recognizing the predictors of disease relapses in patients with anti-aquaporin-4 antibody (AQP4-ab)-positive neuromyelitis optica spectrum disorder (NMOSD) is essential for individualized treatment strategy. We aimed to identify the factors that predicted relapses among patients with AQP4-ab-positive NMOSD, develop outcome prediction models, and validate them in a multicenter validation cohort. Methods: Between January 2015 and December 2020, 820 patients with NMOSD were registered at Huashan Hospital. We retrospectively reviewed their medical records, and included 358 AQP4-ab-positive patients with 1135 treatment episodes. Univariate and multivariate analyses were used to explore the predictors of relapse, severe visual or motor disability during follow-up. A model predicting the 1- and 2-year relapse-free probability was developed and validated in an external validation cohort of 92 patients with 213 treatment episodes. Results: Lower serum AQP4-ab titer (< 1:100), higher Expanded Disability Status Scale (EDSS) score at onset (≥ 2.5), and use of intravenous methylprednisolone (IVMP) at the first attack predicted an overall lower annualized relapse rate. Older age (> 48 years), optic neuritis at onset, and higher onset EDSS score (≥ 2.5) significantly increased the risk for blindness, while IVMP at the first attack and maintenance therapy reduced the risk for blindness. Myelitis at onset increased the possibility of motor disability (EDSS ≥ 6.0), severe motor disability or death (EDSS ≥ 8.0), while maintenance therapy reduced these possibilities. Anderson and Gill model identified that the risk factors predicting recurrent relapses under certain treatment status were female gender, high AQP4-ab titer (≥ 1:100), previous attack under same therapy, lower EDSS score at treatment initiation (< 2.5), and no maintenance therapy or oral prednisone lasting less than 6 months. A nomogram using the above factors showed good discrimination and calibration abilities. The concordance indexes in the primary and validation cohort were 0.66 and 0.65, respectively. Conclusion: This study reports the demographic, clinical and therapeutic predictors of relapse, and severe visual or motor disability in NMOSD. Early identification of patients at risk of unfavorable outcomes is of paramount importance to inform treatment decisions.

Molecular physiology of iron trafficking in Drosophila melanogaster.

Iron homeostasis in insects is less-well understood comparatively to mammals. The classic model organism Drosophila melanogaster has been recently employed to explore how iron is trafficked between and within cells. An outline for iron absorption, systemic delivery, and efflux is thus beginning to emerge. The proteins Malvolio, ZIP13, mitoferrin, ferritin, transferrin, and IRP-1A are key players in these processes. While many features are shared with those in mammals, some physiological differences may also exist. Notable remaining questions include the existence and identification of functional transferrin and ferritin receptors, and of an iron exporter like ferroportin, how systemic iron homeostasis is controlled, and the roles of different tissues in regulating iron physiology. By focusing on aspects of iron trafficking, this review updates on presently known complexities of iron homeostasis in Drosophila.

Pneumonia and systemic inflammatory response syndrome as predictors for difficult-/prolonged-weaning after invasive ventilation in myasthenic crisis: A retrospective analysis of a Chinese cohort.

Weaning from invasive mechanical ventilation (MV) represents a pivotal step for myasthenic crisis (MC) patients. The aim was to evaluate the association between the weaning process and clinical outcomes, as well as to determine the independent predictors for difficult-/prolonged-weaning in MC. MC patients requiring invasive MV were recruited from Jan 2014 through Sep 2020. Among 124 consecutive MC patients, we finally included 66 patients (age 48.4 ±â€¯18.7 years, female 45.5%). According to the WIND (Weaning according to a New Definition) classification, these patients were classified into no-weaning (n = 5, 7.6%), short-weaning (n = 13, 19.7%), difficult-weaning (n = 26, 39.4%), and prolonged-weaning group (n = 22, 33.3%). Four-week functional assessment in short-weaning group was more favorable than that in difficult-/prolonged-weaning group (p<0.001). Length of hospital stay (23.0 (15.0-28.0) vs. 37.5 (27.0-54.8), p<0.001), length of ICU stay (17.0 (8.5-22.5) vs. 34.0 (20.3-45.0), p<0.001), duration on ventilation (6.0 (6.0-8.5) vs. 18.0 (13.3-30.0), p<0.001), and time interval from MV to first weaning (6.0 (6.0-8.0) vs. 11.0 (8.0-20.8), p<0.001) in short-weaning group were significantly shorter than those in difficult-/prolonged-weaning group. Short-weaning group had a lower prevalence of pneumonia (23.1% vs. 75.0%) and systemic inflammatory response syndrome (SIRS) (38.5% vs. 85.4%), and a higher value in the lowest hemoglobin level (123.0 ±â€¯12.9 g/L vs. 108.3 ±â€¯18.1 g/L) and the lowest serum albumin level (33.2 ±â€¯3.4 g/L vs. 29.9 ±â€¯4.2 g/L) than difficult-/prolonged-weaning group. Multivariate logistic regression analysis identified pneumonia and the presence of SIRS within one week of MC as independent predictors for difficult-/prolonged-weaning. The weaning process is associated with clinical outcomes in MC patients requiring ventilation. Pneumonia concurrence and the presence of SIRS within one week of MC were identified as independent predictors for difficult-/prolonged-weaning after invasive MV.

Crepe Cake Structured Layered Double Hydroxide/Sulfur/Graphene as a Positive Electrode Material for Li-S Batteries.

Solving the polysulfide shuttle problem is one of the core challenges for the industrialization of lithium-sulfur batteries. In this work, a triphasic composite of LDH/sulfur/rGO (LDH: layered double hydroxide, rGO: reduced graphene oxide) with a crepe cake like structure is designed and fabricated as a positive electrode material for lithium-sulfur batteries. Sulfur nanoparticles are embedded in the interlayer space of the composite and thus are well protected physically via three-dimensional wrapping and chemically via strong interaction of LDH nanoflakes with lithium polysulfides, such as ionic bonds and S···H hydrogen bonds. In addition, the flexible lamellar structure of the composite with soft graphene layers can tolerate the volume expansion of sulfur during lithiation as well as facilitate ionic permeability and electron transport, which is favorable for the redox reactions of polysulfide. The present work sheds light on the future development and industrialization of lithium-sulfur batteries.

Age­ and brain region­associated alterations of cerebral blood flow in early Alzheimer's disease assessed in AßPPSWE/PS1ΔE9 transgenic mice using arterial spin labeling.

It has been suggested that cerebral blood flow (CBF) alterations may be involved in the pathogenesis of Alzheimer's disease (AD). However, how CBF changes with age has not been detailed in AD, particularly in its early stages. The objective of the present study was to evaluate CBF in four brain regions (the hippocampus, entorhinal cortex, frontoparietal cortex and thalamus) of mice in four age groups, to mimic the respective stages of AD in humans [2 months (pre­clinical), 3.5 months (sub­clinical), 5 months (early­clinical) and 8 months (mid­clinical)], to understand the age­associated changes in selected brain regions and to elucidate the underlying vascular mechanisms. CBF was measured using magnetic resonance imaging­arterial spin labelling (ASL) under identical conditions across the age groups of AßPPSWE/PS1ΔE9 (APP/PS1) transgenic mice with AD. The results indicated age­ and brain region­associated changes in CBF were associated with early AD. More precisely, an age­dependent increase in CBF (in the pre­ and sub­clinical AD groups) was observed in the frontoparietal cortex and thalamus. Conversely, increased CBF demonstrated an age­dependent decline (in the early­ and mid­clinical AD groups) in all examined brain regions. Among the regions, the thalamus had the greatest increase in CBF in the 2 and 3.5 months age groups, which was substantially different compared with the age­matched controls. An extension of vessel area was also noted to be age­ and brain region­dependent. In particular, correlation analysis revealed significant associations of CBF with vessel area in the frontoparietal cortex and thalamus of APP/PS1 mice at ages 2 and 3.5 months, indicating that CBF increase may arise from vessel extension. The results of the present study suggested that ASL can detect age­ and brain region­associated changes in CBF in mice with AD, and that ASL­measured CBF increase may be a potential diagnostic biomarker for early AD. The observation that CBF increase resulted from vessel extension may aid in the understanding of the vascular role in age­associated development of AD pathology, and provide preclinical evidence for AD patient management.