Colloidal Synthesis of Metal Nanocrystals: From Asymmetrical Growth to Symmetry Breaking.

Nanocrystals offer a unique platform for tailoring the physicochemical properties of solid materials to enhance their performances in various applications. While most work on controlling their shapes revolves around symmetrical growth, the introduction of asymmetrical growth and thus symmetry breaking has also emerged as a powerful route to enrich metal nanocrystals with new shapes and complex morphologies as well as unprecedented properties and functionalities. The success of this route critically relies on our ability to lift the confinement on symmetry by the underlying unit cell of the crystal structure and/or the initial seed in a systematic manner. This Review aims to provide an account of recent progress in understanding and controlling asymmetrical growth and symmetry breaking in a colloidal synthesis of noble-metal nanocrystals. With a touch on both the nucleation and growth steps, we discuss a number of methods capable of generating seeds with diverse symmetry while achieving asymmetrical growth for mono-, bi-, and multimetallic systems. We then showcase a variety of symmetry-broken nanocrystals that have been reported, together with insights into their growth mechanisms. We also highlight their properties and applications and conclude with perspectives on future directions in developing this class of nanomaterials. It is hoped that the concepts and existing challenges outlined in this Review will drive further research into understanding and controlling the symmetry breaking process.

Template-Directed Synthesis of Colloidal Hollow Particles: Mind the Material Used for the Template.

The dissolution of a polymeric solid typically starts with the absorption of solvent molecules, followed by swelling and volume expansion. Only when the extent of swelling reaches a threshold can the polymer chains be disentangled and then dissolved into the solvent. When the polymeric solid is encapsulated in a rigid shell, the swelling process will be impeded. Despite the widespread use of this process, it is rarely discussed in the literature how the polymeric solid is dissolved from the core for the generation of colloidal hollow particles. Recent studies have started to shed light on the mechanistic details involved in the formation of hollow particles through a template-directed process. Depending on the nature of the material used for the template, the removal of the template may involve different mechanisms and pathways, leading to the formation of distinct products. Here, a number of examples are used to illustrate this important phenomenon that is largely neglected in the literature. This article also discusses how the swelling of a polymeric template encapsulated in a rigid shell can be leveraged to fabricate new types of functional colloidal particles.

Regulating Electrocatalytic Oxygen Reduction Activity of a Metal Coordination Polymer via d-π Conjugation.

Non-noble transition metal complexes have attracted growing interest as efficient electrocatalysts for oxygen reduction reaction (ORR) while their activities still lack rational and effective regulation. Herein, we propose a d-π conjugation strategy for rough and fine tuning of ORR activity of TM-BTA (TM=Mn/Fe/Co/Ni/Cu, BTA=1,2,4,5-benzenetetramine) coordination polymers. By first-principle calculations, we elucidate that the strong d-π conjugation elevates the dxz /dyz orbitals of TM centers to enhance intermediate adsorption and strengthens the electronic modulation effect from substitute groups on ligands. Based on this strategy, Co-TABQ (tetramino benzoquinone) is found to approach the top of ORR activity volcano. The synthesized Co-TABQ with atomically distributed Co on carbon nanotubes exhibits a half-wave potential of 0.85 V and a specific current of 127 mA mgmetal -1 at 0.8 V, outperforming the benchmark Pt/C. The high activity, low peroxide yield, and considerable durability of Co-BTA and Co-TABQ promise their application in oxygen electrocatalysis. This study provides mechanistic insight into the rational design of transition metal complex catalysts.

A Meta-Analysis of the Reliability of Second Language Listening Tests (1991-2022).

To investigate the reliability of L2 listening tests and explore potential factors affecting the reliability, a reliability generalization (RG) meta-analysis was conducted in the present study. A total number of 122 alpha coefficients of L2 listening tests from 92 published articles were collected and submitted to a linear mixed effects RG analysis. The papers were coded based on a coding scheme consisting of 16 variables classified into three categories: study features, test features, and statistical results. The results showed an average reliability of 0.818 (95% CI: 0.803 to 0.833), with 40% of reliability estimates falling below the lower bound of CI. The presence of publication bias and heterogeneity was found in the reliability of L2 listening tests, indicating that low reliability coefficients were likely omitted from some published studies. In addition, two factors predicting the reliability of L2 listening tests were the number of items and test type (standardized and researcher- or teacher-designed tests). The study also found that reliability is not a moderator of the relationship between L2 listening scores and theoretically relevant constructs. Reliability induction was identified in reporting the reliability of L2 listening tests, too. Implications for researchers and teachers are discussed.

Phylogenomics, taxonomy and morphological characters of the Microdochiaceae (Xylariales, Sordariomycetes).

Species of the family Microdochiaceae (Xylariales, Sordariomycetes) have been reported from worldwide, and collected from different plant hosts. The proposed new genus and two new species, viz., Macroidriella gen. nov., M.bambusae sp. nov. and Microdochiumaustrale sp. nov., are based on multi-locus phylogenies from a combined dataset of ITS rDNA, LSU, RPB2 and TUB2 with morphological characteristics. Microdochiumsinense has been collected from diseased leaves of Phragmitesaustralis and this is the first report of the fungus on this host plant. Simultaneously, we annotated 10,372 to 11,863 genes, identified 4,909 single-copy orthologous genes, and conducted phylogenomic analysis based on genomic data. A gene family analysis was performed and it will expand the understanding of the evolutionary history and biodiversity of the Microdochiaceae. The detailed descriptions and illustrations of species are provided.

Nanoparticles for inducing Gaucher disease-like damage in cancer cells.

Nutrient avidity is one of the most distinctive features of tumours. However, nutrient deprivation has yielded limited clinical benefits. In Gaucher disease, an inherited metabolic disorder, cells produce cholesteryl-glucoside which accumulates in lysosomes and causes cell damage. Here we develop a nanoparticle (AbCholB) to emulate natural-lipoprotein-carried cholesterol and initiate Gaucher disease-like damage in cancer cells. AbCholB is composed of a phenylboronic-acid-modified cholesterol (CholB) and albumin. Cancer cells uptake the nanoparticles into lysosomes, where CholB reacts with glucose and generates a cholesteryl-glucoside-like structure that resists degradation and aggregates into microscale crystals, causing Gaucher disease-like damage in a glucose-dependent manner. In addition, the nutrient-sensing function of mTOR is suppressed. It is observed that normal cells escape severe damage due to their inferior ability to compete for nutrients compared with cancer cells. This work provides a bioinspired strategy to selectively impede the metabolic action of cancer cells by taking advantage of their nutrient avidity.

Early immune surveillance to predict cytomegalovirus outcomes after allogeneic hematopoietic stem cell transplantation.

Background: There is no method of predicting human cytomegalovirus (HCMV) outcomes in allogeneic hematopoietic stem cell transplant recipients clinically, leading in some cases to excessive or insufficient antiviral therapy. We evaluated the early immune response of recipients with disparate HCMV outcomes. Methods: The HCMV outcomes of recipients were determined by long-term monitoring of HCMV DNA levels posttransplant. HCMV IgG and IgM concentrations at 1 week before and 1 week after transplantation, absolute lymphocyte counts, and HCMV-specific IFN-γ secreting cells at 1 month posttransplant were evaluated based on HCMV outcome. Results: All recipients were negative for HCMV IgM. Significant differences between recipients with and without HCMV reactivation were observed in pre- and post-transplant HCMV IgG antibody levels, absolute lymphocyte counts, and HCMV-specific IFN-γ secreting cells (P < 0.05). HCMV IgG antibody levels significantly increased after transplantation in recipients with HCMV reactivation (P = 0.032), but not in those without reactivation. Multivariate analysis revealed that except for the absolute lymphocyte count these biomarkers were related to HCMV reactivation, independent of other clinical factors. In time-to-event analyses, lower levels of these biomarkers were associated with an increased 150-day cumulative incidence of HCMV reactivation (log-rank P < 0.05). In recipients with HCMV reactivation, the duration of HCMV DNAemia had negative correlation with HCMV-specific IFN-γ-secreting cells (P = 0.015, r = -0.372). The relationships between the peak HCMV DNA load and absolute lymphocyte count and HCMV-specific IFN-γ-secreting cells followed the same trends (P = 0.026, r = -0.181 and P = 0.010, r = -0.317). Conclusions: HCMV IgG, absolute lymphocyte count, and HCMV-specific IFN-γ secreting cells represent the humoral and cellular immune response. Early monitoring of these immune markers could enable prediction of HCMV outcomes posttransplant and assessment of the severity of HCMV DNAemia.

Transcriptomics reveals immune-metabolism disorder in acute-on-chronic liver failure in rats.

Acute-on-chronic liver failure (ACLF) is clinical syndrome with high mortality rate. This study aimed to perform detailed transcriptomic analysis in liver cirrhosis-based ACLF rats to elucidate ACLF pathogenesis. ACLF was induced by combined porcine serum with D-galactosamine and lipopolysaccharide. Gene expression profile of liver tissues from ACLF rats was generated by transcriptome sequencing to reveal the molecular mechanism. ACLF rats successfully developed with typical characteristics. Total of 2,354/3,576 differentially expressed genes were identified when ACLF was compared to liver cirrhosis and normal control, separately. The functional synergy analysis revealed prominent immune dysregulation at ACLF stage, whereas metabolic disruption was significantly down-regulated. Relative proportions of innate immune-related cells showed significant elevation of monocytes and macrophages, whereas adaptive immune-related cells were reduced. The seven differentially expressed genes underlying the ACLF molecular mechanisms were externally validated, among them THBS1, IL-10, and NR4A3 expressions were confirmed in rats, patient transcriptomics, and liver biopsies, verifying their potential value in the ACLF pathogenesis. This study indicates immune-metabolism disorder in ACLF rats, which may provide clinicians new targets for improving intervention strategies.