Tunable green syngas generation from CO2 and H2O with sunlight as the only energy input.

The carbon-neutral synthesis of syngas from CO2 and H2O powered by solar energy holds grand promise for solving critical issues such as global warming and the energy crisis. Here we report photochemical reduction of CO2 with H2O into syngas using core/shell Au@Cr2O3 dual cocatalyst-decorated multistacked InGaN/GaN nanowires (NWs) with sunlight as the only energy input. First-principle density functional theory calculations revealed that Au and Cr2O3 are synergetic in deforming the linear CO2 molecule to a bent state with an O-C-O angle of 116.5°, thus significantly reducing the energy barrier of CO2RR compared with that over a single component of Au or Cr2O3. Hydrogen evolution reaction was promoted by the same cocatalyst simultaneously. By combining the cooperative catalytic properties of Au@Cr2O3 with the distinguished optoelectronic virtues of the multistacked InGaN NW semiconductor, the developed photocatalyst demonstrated high syngas activity of 1.08 mol/gcat/h with widely tunable H2/CO ratios between 1.6 and 9.2 under concentrated solar light illumination. Nearly stoichiometric oxygen was evolved from water splitting at a rate of 0.57 mol/gcat/h, and isotopic testing confirmed that syngas originated from CO2RR. The solar-to-syngas energy efficiency approached 0.89% during overall CO2 reduction coupled with water splitting. The work paves a way for carbon-neutral synthesis of syngas with the sole inputs of CO2, H2O, and solar light.

Selective Electrified Propylene-to-Propylene Glycol Oxidation on Activated Rh-Doped Pd.

Renewable-energy-powered electrosynthesis has the potential to contribute to decarbonizing the production of propylene glycol, a chemical that is used currently in the manufacture of polyesters and antifreeze and has a high carbon intensity. Unfortunately, to date, the electrooxidation of propylene under ambient conditions has suffered from a wide product distribution, leading to a low faradic efficiency toward the desired propylene glycol. We undertook mechanistic investigations and found that the reconstruction of Pd to PdO occurs, followed by hydroxide formation under anodic bias. The formation of this metastable hydroxide layer arrests the progressive dissolution of Pd in a locally acidic environment, increases the activity, and steers the reaction pathway toward propylene glycol. Rh-doped Pd further improves propylene glycol selectivity. Density functional theory (DFT) suggests that the Rh dopant lowers the energy associated with the production of the final intermediate in propylene glycol formation and renders the desorption step spontaneous, a concept consistent with experimental studies. We report a 75% faradic efficiency toward propylene glycol maintained over 100 h of operation.

An Active and Robust Catalytic Architecture of NiCo/GaN Nanowires for Light-Driven Hydrogen Production from Methanol.

On-site hydrogen production from liquid organic hydrogen carriers e.g., methanol provides an emerging strategy for the safe storage and transportation of hydrogen. Herein, a catalytic architecture consisting of nickel-cobalt nanoclusters dispersed on gallium nitride nanowires supported by silicon for light-driven hydrogen production from methanol is reported. By correlative microscopic, spectroscopic characterizations, and density functional theory calculations, it is revealed that NiCo nanoclusters work in synergy with GaN nanowires to enable the achievement of a significantly reduced activation energy of methanol dehydrogenation by switching the potential-limiting step from *CHO → *CO to *CH3O → *CH2O. In combination with the marked photothermal effect, a high hydrogen rate of 5.62 mol·gcat-1·h-1 with a prominent turnover frequency of 43,460 h-1 is achieved at 5 Wcm-2 without additional energy input. Remarkably, the synergy between Co and Ni, in combination with the unique surface of GaN, renders the architecture with outstanding resistance to sintering and coking. The architecture thereby exhibits a high turnover number of >16,310,000 over 600 h. Outdoor testing validates the viability of the architecture for active and robust hydrogen evolution under natural concentrated sunlight. Overall, this work presents a promising architecture for on-site hydrogen production from CH3OH by virtually unlimited solar energy.

MiR-421 mediates PM2.5-induced endothelial dysfunction via crosstalk between bronchial epithelial and endothelial cells.

OBJECTIVE: PM2.5 is closely linked to vascular endothelial injury and has emerged as a major threat to human health. Our previous research indicated that exposure to PM2.5 induced an increased release of miR-421 from the bronchial epithelium. However, the role of miR-421 in PM2.5-induced endothelial injury remains elusive. MATERIALS AND METHODS: We utilized a subacute PM2.5-exposure model in mice in vivo and an acute injury cell model in vitro to simulate PM2.5-associated endothelial injury. We also used quantitative real-time polymerase chain reaction, western blot, enzyme-linked immunosorbent assay, and immunohistochemistry to investigate the role of miR-421 in PM2.5-induced endothelial injury. RESULTS: Our findings reveal that inhibition of miR-421 attenuated PM2.5-induced endothelial injury and hypertension. Mechanistically, miR-421 inhibited the expression of angiotensin-converting enzyme 2 (ACE2) in human umbilical vein endothelial cells and upregulated the expression of the downstream molecule inducible nitric oxide synthase (iNOS), thereby exacerbating PM2.5-induced endothelial injury. CONCLUSIONS: Our results indicate that PM2.5 exposure facilitates crosstalk between bronchial epithelial and endothelial cells via miR-421/ACE2/iNOS signaling pathway, mediating endothelial damage and hypertension. MiR-421 inhibition may offer a new strategy for the prevention and treatment of PM2.5-induced vascular endothelial injury.

Air-Promoted Light-Driven Hydrogen Production from Bioethanol over Core/Shell Cr2O3@GaN Nanoarchitecture.

Light-driven hydrogen production from biomass derivatives offers a path towards carbon neutrality. It is often however operated with the limitations of sluggish kinetics and severe coking. Herein, a disruptive air-promoted strategy is explored for efficient and durable light-driven hydrogen production from ethanol over a core/shell Cr2O3@GaN nanoarchitecture. The correlative computational and experimental investigations show ethanol is energetically favorable to be adsorbed on the Cr2O3@GaN interface, followed by dehydrogenation toward acetaldehyde and protons by photoexcited holes. The released protons are then consumed for H2 evolution by photogenerated electrons. Afterward, O2 can be evolved into active oxygen species and promote the deprotonation and C-C cleavage of the key C2 intermediate, thus significantly lowering the reaction energy barrier of hydrogen evolution and removing the carbon residual with inhibited overoxidation. Consequently, hydrogen is produced at a high rate of 76.9 mole H2 per gram Cr2O3@GaN per hour by only feeding ethanol, air, and light, leading to the achievement of a turnover number of 266,943,000 mole H2 per mole Cr2O3 over a long-term operation of 180 hours. Notably, an unprecedented light-to-hydrogen efficiency of 17.6 % is achieved under concentrated light illumination. The simultaneous generation of aldehyde from ethanol dehydrogenation enables the process more economically promising.

Dicarboxylic Acid-Assisted Surface Oxide Removal and Passivation of Indium Antimonide Colloidal Quantum Dots for Short-Wave Infrared Photodetectors.

Heavy-metal-free III-V colloidal quantum dots (CQDs) are promising materials for solution-processed short-wave infrared (SWIR) photodetectors. Recent progress in the synthesis of indium antimonide (InSb) CQDs with sizes smaller than the Bohr exciton radius enables quantum-size effect tuning of the band gap. However, it has been challenging to achieve uniform InSb CQDs with band gaps below 0.9 eV, as well as to control the surface chemistry of these large-diameter CQDs. This has, to date, limited the development of InSb CQD photodetectors that are sensitive to ≥ ${\ge }$ 1400 nm light. Here we adopt solvent engineering to facilitate a diffusion-limited growth regime, leading to uniform CQDs with a band gap of 0.89 eV. We then develop a CQD surface reconstruction strategy that employs a dicarboxylic acid to selectively remove the native In/Sb oxides, and enables a carboxylate-halide co-passivation with the subsequent halide ligand exchange. We find that this strategy reduces trap density by half compared to controls, and enables electronic coupling among CQDs. Photodetectors made using the tailored CQDs achieve an external quantum efficiency of 25 % at 1400 nm, the highest among III-V CQD photodetectors in this spectral region.

Manipulation of Particle/Cell Based on Compressibility in a Divergent Microchannel by Surface Acoustic Wave.

The mechanical properties (compressibility or deformability) of cells are closely related to their death, migration, and differentiation. Accurate separation and manipulation of bioparticles based on these mechanical properties are still a challenging in the field of acoustofluidics. In this work, based on surface acoustic waves (SAW) and divergent microchannels, we developed a new method for separating and detecting particles or cells with different compressibility. The difference in acoustic radiation force (Fr) caused by compressibility are gradually amplified and accumulated by decreasing the flow velocity, and they are finally reflected in the particle migration distance. During the transverse migration process, the alternating dominance of the acoustic radiation force and the Stokes resistance force (Fs) drives the particles to create three typical migration patterns: intermittent migration, compound migration, and near-wall migration. In the present tilted SAW device, a 91% separation success rate of ∼10 µm polystyrene (PS) and polydimethylsiloxane (PDMS) particles can be achieved by optimizing the acoustic field input power and the fluid velocity. The application potential of the present divergent microchannel is validated by separating the myelogenous leukemia cell K562 and the natural killer cell NK92 that have similar densities and sizes (∼15 µm) but different compressibility. The results of this work are expected to provide valuable insights into the acoustofluidics separation and detection of the cells that are with different compressibility.

Fast and Reversible Quasi-Solid-State Anion Exchange in Highly Luminescent CsPbX3 Perovskite Nanocrystals for Dual-Mode Encryption-Decryption.

Solid-state anion exchange method is easy to handle and beneficial to improve stability of CsPbX3 (X = Cl, Br, I) perovskites nanocrystals (NCs) with respect to anion exchange in liquid phase. However, the corresponding exchange rate is rather slow due to the limited diffusion rate of anions from solid phases, resulting in mixed-halide perovskite NCs. Herein,  a fast and reversible post-synthetic quasi-solid-state anion exchange method in CsPbX3 NCs with inorganic potassium halide KX salts/polyvinylpyrrolidone (PVP) thin film is firstly reported. Original morphology of the exchanged NCs is well-preserved for all samples. Complete anion exchange from Br- to Cl- or I- is successfully achieved in CsPbX3 NCs within ≈20 min through possible vacancies-assisted ion exchange mechanism, under ambient conditions and vice versa. Particularly, Br- -exchanged CsPbCl3 and CsPbI3 NCs exhibit improved optical properties. Encouraged by the attractive fluorescence and persistent luminescence as well as good stability of the resulted CsPbX3 NCs, an effective dual-mode information storage-reading application is demonstrated.  It is believed that this method can open a new avenue for the synthesis of other direct-synthesis challenging quantum-confined perovskite NCs/nanoplates/nanodisks or CsSnX3 NCs/thin film and provide an opportunity for advanced information storage compatible for practical applications.

Divorce rate in monogamous birds increases with male promiscuity and migration distance.

Socially monogamous birds may break up their partnership by a so-called 'divorce' behaviour. Divorce rates vary immensely across avian taxa that have a predominantly monogamous social mating system. Although various factors associated with divorce have been tested, broad-scale drivers of divorce rate remain contentious. Moreover, the influence of sexual roles in divorce still needs further investigation because of the conflicting interests of males and females over mating and fertilization. Here, we applied phylogenetic comparative methods to analyse one of the largest datasets ever compiled that included divorce rates from published studies of 186 avian species from 25 orders and 61 families. We tested correlations between divorce rate and a group of factors: 'promiscuity' of both sexes (propensity to polygamy), migration distance and adult mortality. Our results showed that only male promiscuity, but not female promiscuity, had a positive relationship with divorce rate. Furthermore, migration distance was positively correlated with divorce rate, whereas adult mortality rate showed no direct relationship with divorce rate. These findings indicated that divorce might not be a simple adaptive (by sexual selection) or non-adaptive strategy (by accidental loss of a partner) in birds but it could be a mixed response to sexual conflict and stress from the ambient environment.

X-Ray Triggered Coordination-Bond Breakage in Dysprosium-Organic Framework and its Impact on Magnetic Properties.

Photosensitive lanthanide-based single-molecule magnets (Ln-SMM) are very attractive for their potential applications in information storage, switching, and sensors. However, the light-driven structural transformation in Ln-SMMs hardly changes the coordination number of the lanthanide ion. Herein, for the first time it is reported that X-ray (λ=0.71073 Å) irradiation can break the coordination bond of Dy-OH2 in the three-dimensional (3D) metal-organic framework Dy2 (amp2 H2 )3 (H2 O)6 ⋅ 4H2 O (MDAF-5), in which the {Dy2 (OPO)2 } dimers are cross-linked by dianthracene-phosphonate ligands. The structural transformation proceeds in a single-crystal-to-single-crystal (SC-SC) fashion, forming the new phase Dy2 (amp2 H2 )3 (H2 O)4 ⋅ 4H2 O (MDAF-5-X). The phase transition is accompanied by a significant change in magnetic properties due to the alteration in coordination geometry of the DyIII ion from a distorted pentagonal bipyramid in MDAF-5 to a distorted octahedron in MDAF-5-X.

A Multicenter Study on Preoperative Assessment of Lymphovascular Space Invasion in Early-Stage Cervical Cancer Based on Multimodal MR Radiomics.

BACKGROUND: As lymphovascular space invasion (LVSI) was closely related to lymph node metastasis and prognosis, the preoperative assessment of LVSI in early-stage cervical cancer is crucial for patients. PURPOSE: To develop and validate nomogram based on multimodal MR radiomics to assess LVSI status in cervical cancer patients. STUDY TYPE: Retrospective. POPULATION: The study included 168 cervical cancer patients, of whom 129 cases (age 51.36 ± 9.99 years) from institution 1 were included as the training cohort and 39 cases (age 52.59 ± 10.23 years) from institution 2 were included as the external test cohort. FIELD STRENGTH/SEQUENCE: There were 1.5 T and 3.0 T MRI scans (T1-weighted imaging [T1WI], fat-saturated T2-weighted imaging [FS-T2WI], and contrast-enhanced [CE]). ASSESSMENT: Six machine learning models were built and selected to construct the radiomics signature. The nomogram model was constructed by combining the radiomics signature with the clinical signature, which was then validated for discrimination, calibration, and clinical usefulness. STATISTICAL TESTS: The clinical characteristics were compared using t-tests, Mann-Whitney U tests, or chi-square tests. The Spearman and LASSO methods were used to select radiomics features. The receiver operating characteristic (ROC) analysis was performed, and the area under the curve (AUC), accuracy, sensitivity, and specificity were calculated. RESULTS: The logistic regression (LR) model performed best in each sequence. The AUC of CE-T1-T2WI-combined was the highest in the LR model, with an AUC of 0.775 (95% CI: 0.570-0.979) in external test cohort. The nomogram showed high predictive performance in the training (AUC: 0.883 [95% CI: 0.823-0.943]) and test cohort (AUC: 0.830 [95% CI: 0.657-1.000]) for predicting LVSI. Decision curve analysis demonstrated that the nomogram was clinically useful. DATA CONCLUSION: Our findings suggest that the proposed nomogram model based on multimodal MRI of CE T1WI-T2WI-combined could be used to assess LVSI status in early cervical cancer. EVIDENCE LEVEL: 4. TECHNICAL EFFICACY: Stage 2.

Multi-omics analyses of serum metabolome, gut microbiome and brain function reveal dysregulated microbiota-gut-brain axis in bipolar depression.

The intricate processes of microbiota-gut-brain communication in modulating human cognition and emotion, especially in the context of mood disorders, have remained elusive. Here we performed faecal metagenomic, serum metabolomics and neuroimaging studies on a cohort of 109 unmedicated patients with depressed bipolar disorder (BD) patients and 40 healthy controls (HCs) to characterise the microbial-gut-brain axis in BD. Across over 12,000 measured metabolic features, we observed a large discrepancy (73.54%) in the serum metabolome between BD patients and HCs, spotting differentially abundant microbial-derived neuroactive metabolites including multiple B-vitamins, kynurenic acid, gamma-aminobutyric acid and short-chain fatty acids. These metabolites could be linked to the abundance of gut microbiota presented with corresponding biosynthetic potentials, including Akkermansia muciniphila, Citrobacter spp. (Citrobacter freundii and Citrobacter werkmanii), Phascolarctobacterium spp., Yersinia spp. (Yersinia frederiksenii and Yersinia aleksiciae), Enterobacter spp. (Enterobacter cloacae and Enterobacter kobei) and Flavobacterium spp. Based on functional neuroimaging, BD-related neuroactive microbes and metabolites were discovered as potential markers associated with BD-typical features of functional connectivity of brain networks, hinting at aberrant cognitive function, emotion regulation, and interoception. Our study combines gut microbiota and neuroactive metabolites with brain functional connectivity, thereby revealing potential signalling pathways from the microbiota to the gut and the brain, which may have a role in the pathophysiology of BD.

Carboxymethyl cellulose-alginate interpenetrating hydroxy ethyl methacrylate crosslinked polyvinyl alcohol reinforced hybrid hydrogel templates with improved biological performance for cardiac tissue engineering.

Cardiac tissue engineering is an emerging approach for cardiac regeneration utilizing the inherent healing responses elicited by the surviving heart using biomaterial templates. In this study, we aimed to develop hydrogel scaffolds for cardiac tissue regeneration following myocardial infarction (MI). Two superabsorbent hydrogels, CAHA2A and CAHA2AP, were developed employing interpenetration chemistry. CAHA2A was constituted with alginate, carboxymethyl cellulose, (hydroxyethyl) methacrylate, and acrylic acid, where CAHA2AP was prepared by interpenetrated CAHA2A with polyvinyl alcohol. Both hydrogels displayed superior physiochemical characteristics, as determined by attenuated total reflection infrared spectroscopy spectral analysis, differential scanning calorimetry measurements, tensile testing, contact angle, water profiling, dye release, and conductivity. In vitro degradation of the hydrogels displayed acceptable weight composure and pH changes. Both hydrogels were hemocompatible, and biocompatible as evidenced by direct contact and MTT assays. The hydrogels promoted anterograde and retrograde migration as determined by the z-stack analysis using H9c2 cells grown with both gels. Additionally, the coculture of the hydrogels with swine epicardial adipose tissue cells and cardiac fibroblasts resulted in synchronous growth without any toxicity. Also, both hydrogels facilitated the production of extracellular matrix by the H9c2 cells. Overall, the findings support an appreciable in vitro performance of both hydrogels for cardiac tissue engineering applications.

Analysis of the Pattern Shapes Obtained By Micro/Nanospherical Lens Photolithography.

Micro/nanospherical lens photolithography (SLPL) constitutes an efficient and precise micro/nanofabrication methodology. It offers advantages over traditional nanolithography approaches, such as cost-effectiveness and ease of implementation. By using micrometer-sized microspheres, SLPL enables the preparation of subwavelength scale features. This technique has gained attention due to its potential applications. However, the SLPL process has a notable limitation in that it mostly produces simple pattern shapes, mainly consisting of circular arrays. There has been a lack of theoretical analysis regarding the possible shapes that can be created. In our experiments, we successfully prepared annular and ring-with-hole pattern shapes. To address this limitation, we applied the Mie scattering theory to systematically analyze and summarize the various patterns that can be obtained through the SLPL process. We also proposed methods to predict and obtain different patterns. This theoretical analysis enhances the understanding of SLPL and expands its potential applications, making it a valuable area for further research.

Two-dimensional III-nitride alloys: electronic and chemical properties of monolayer Ga(1-x)AlxN.

Potential applications of III-nitrides have led to their monolayer allotropes, i.e., two-dimensional (2D) III-nitrides, having attracted much attention. Recently, alloying has been demonstrated as an effective method to control the properties of 2D materials. In this study, the stability, and the electronic and chemical properties of monolayer Ga(1-x)AlxN alloys were investigated employing density functional theory (DFT) calculations and the cluster expansion (CE) method. The results show that 2D Ga(1-x)AlxN alloys are thermodynamically stable and complete miscibility in the alloys can be achieved at ambient temperature (>85 K). By analyzing CE results, the atomic arrangement of 2D Ga(1-x)AlxN was revealed, showing that Ga/Al atoms tend to mix with the Al/Ga atoms in their next nearest site. The band gaps of Ga(1-x)AlxN random alloys can be tuned by varying the chemical composition, and the corresponding bowing parameter was calculated as -0.17 eV. Biaxial tensile strain was also found to change the band gap values of Ga(1-x)AlxN random alloys ascribed to its modifications to the CBM positions. The chemical properties of Ga(1-x)AlxN can also be significantly altered by strain, making them good candidates as photocatalysts for water splitting. The present study can play a crucial role in designing and optimizing 2D III-nitrides for next-generation electronics and photocatalysis.

The synergistic effect of trap deactivation and hysteresis suppression at grain boundaries in perovskite interfaces via multifunctional groups.

In spite of the outstanding photoelectric properties of perovskite materials, numerous defects produced in the preparation process eventually result in decomposition of the perovskite layer. To date, the mechanism of defect passivation and hysteresis reduction via additive engineering has still been obscure for perovskite materials, which seriously restricts performance improvement of the devices. Herein, conductive atomic force microscopy (C-AFM) and Kelvin probe force microscopy (KPFM) measurements were applied to probe carbamic acid ethyl ester (EU)-based trap passivation and suppression of hysteresis in perovskite films. The results indicate that the internal interaction between multifunctional bonds ("CO" and "-NH2") of EU and Pb2+ ions of the perovskite may inactivate the trap state and inhibit ion migration within sub-grains and grain boundaries (GBs), resulting in improvement of the long-term stability of the cells. In consequence, the EU-modified champion device prepared in all-air achieved a power conversion efficiency (PCE) of 20.10%, one of the high performances for the devices fabricated in air to date. In short, this work will propose some interesting speculation about ion migration as well as its influence on hysteresis in perovskite materials.

Structural basis for guide RNA trimming by RNase D ribonuclease in Trypanosoma brucei.

Infection with kinetoplastid parasites, including Trypanosoma brucei (T. brucei), Trypanosoma cruzi (T. cruzi) and Leishmania can cause serious disease in humans. Like other kinetoplastid species, mRNAs of these disease-causing parasites must undergo posttranscriptional editing in order to be functional. mRNA editing is directed by gRNAs, a large group of small RNAs. Similar to mRNAs, gRNAs are also precisely regulated. In T. brucei, overexpression of RNase D ribonuclease (TbRND) leads to substantial reduction in the total gRNA population and subsequent inhibition of mRNA editing. However, the mechanisms regulating gRNA binding and cleavage by TbRND are not well defined. Here, we report a thorough structural study of TbRND. Besides Apo- and NMP-bound structures, we also solved one TbRND structure in complexed with single-stranded RNA. In combination with mutagenesis and in vitro cleavage assays, our structures indicated that TbRND follows the conserved two-cation-assisted mechanism in catalysis. TbRND is a unique RND member, as it contains a ZFD domain at its C-terminus. In addition to T. brucei, our studies also advanced our understanding on the potential gRNA degradation pathway in T. cruzi, Leishmania, as well for as other disease-associated parasites expressing ZFD-containing RNDs.

From marine to freshwater environment: A review of the ecotoxicological effects of microplastics.

Microplastics (MPs) have been widely detected in the world's water, which may pose a significant threat to the ecosystem as a whole and have been a subject of much attention because their presence impacts seas, lakes, rivers, and even the Polar Regions. There have been numerous studies that report direct adverse effects on marine organisms, but only a few have explored their ecological effects on freshwater organisms. In this field, there is still a lack of a systematic overview of the toxic effects and mechanisms of MPs on aquatic organisms, as well as a consistent understanding of the potential ecological consequences. This review describes the fate and impact on marine and freshwater aquatic organisms. Further, we examine the toxicology of MPs in order to uncover the relationship between aquatic organism responses to MPs and ecological disorders. In addition, an overview of the factors that may affect the toxicity effects of MPs on aquatic organisms was presented along with a brief examination of their identification and characterization. MPs were discussed in terms of their physicochemical properties in relation to their toxicological concerns regarding their bioavailability and environmental impact. This paper focuses on the progress of the toxicological studies of MPs on aquatic organisms (bacteria, algae, Daphnia, and fish, etc.) of different trophic levels, and explores its toxic mechanism, such as behavioral alternations, metabolism disorders, immune response, and poses a threat to the composition and stability of the ecosystem. We also review the main factors affecting the toxicity of MPs to aquatic organisms, including direct factors (polymer types, sizes, shapes, surface chemistry, etc.) and indirect factors (persistent organic pollutants, heavy metal ions, additives, and monomer, etc.), and the future research trends of MPs ecotoxicology are also pointed out. The findings of this study will be helpful in guiding future marine and freshwater rubbish studies and management strategies.

Exosomes Derived from Human Adipose-Derived Stem Cells Cannot Distinctively Promote Graft Survival in Cryopreservation Fat Grafting.

BACKGROUND: Cryopreserved fat has limited clinical applications due to its rapid absorption, high degree of fibrosis, and risk of complications after grafting. Many studies have verified that Adipose-derived mesenchymal stem cell-derived exosomes (ADSC-Exos) can improve fresh fat graft survival. This study assessed whether ADSC-Exos could improve the survival of cryopreserved fat grafts. METHODS: Exosomes were isolated from human ADSCs were subcutaneously engrafted with adipose tissues stored under different conditions (fresh; cryopreserved for 1 month) into the backs of BALB/c nude mice (n = 24), and exosomes or PBS were administered weekly. Grafts were harvested at 1, 2, 4, and 8 weeks, and fat retention rate, histologic, and immunohistochemical analyses were conducted. RESULTS: At 1, 2, and 4 weeks after the transfer, cryopreserved fat grafts in groups of exosome-treated showed better fat integrity, fewer oil cysts, and reduced fibrosis. Further investigations of macrophage infiltration and neovascularization revealed that those exosomes increased the number of M2 macrophages at 2 and 4 weeks (p<0.05), but had limited impact on vascularization (p>0.05). It's important to note that no significant differences (p>0.05) were observed between the two groups in both histological and immunohistochemical evaluations at 8 weeks post-transplantation. CONCLUSIONS: This study suggests that ADSC-Exos could improve the survival of cryopreserved fat grafts in the short term (within 4 weeks), but the overall improvement was poor (after 8 weeks). This suggests that the utility of using ADSC-Exos to treat cryopreserved adipose tissue grafts is limited. NO LEVEL ASSIGNED: This journal requires that authors assign a level of evidence to each submission to which Evidence-Based Medicine rankings are applicable. This excludes Review Articles, Book Reviews, and manuscripts that concern Basic Science, Animal Studies, Cadaver Studies, and Experimental Studies. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Structural Insight into Polymerase Mechanism via a Chiral Center Generated with a Single Selenium Atom.

DNA synthesis catalyzed by DNA polymerase is essential for all life forms, and phosphodiester bond formation with phosphorus center inversion is a key step in this process. Herein, by using a single-selenium-atom-modified dNTP probe, we report a novel strategy to visualize the reaction stereochemistry and catalysis. We capture the before- and after-reaction states and provide explicit evidence of the center inversion and in-line attacking SN2 mechanism of DNA polymerization, while solving the diastereomer absolute configurations. Further, our kinetic and thermodynamic studies demonstrate that in the presence of Mg2+ ions (or Mn2+), the binding affinity (Km) and reaction selectivity (kcat/Km) of dGTPαSe-Rp were 51.1-fold (or 19.5-fold) stronger and 21.8-fold (or 11.3-fold) higher than those of dGTPαSe-Sp, respectively, indicating that the diastereomeric Se-Sp atom was quite disruptive of the binding and catalysis. Our findings reveal that the third metal ion is much more critical than the other two metal ions in both substrate recognition and bond formation, providing insights into how to better design the polymerase inhibitors and discover the therapeutics.