Electrified Operando-Freezing of Electrocatalytic CO2 Reduction Cells for Cryogenic Electron Microscopy.

The ability to freeze and stabilize reaction intermediates in their metastable states and obtain their structural and chemical information with high spatial resolution is critical to advance materials technologies such as catalysis and batteries. Here, we develop an electrified operando-freezing methodology to preserve these metastable states under electrochemical reaction conditions for cryogenic electron microscopy (cryo-EM) imaging and spectroscopy. Using Cu catalysts for CO2 reduction as a model system, we observe restructuring of the Cu catalyst in a CO2 atmosphere while the same catalyst remains intact in air at the nanometer scale. Furthermore, we discover the existence of a single valence Cu (1+) state and C-O bonding at the electrified liquid-solid interface of the operando-frozen samples, which are key reaction intermediates that traditional ex situ measurements fail to detect. This work highlights our novel technique to study the local structure and chemistry of electrified liquid-solid interfaces, with broad impact beyond catalysis.

Cryogenic Electron Microscopy for Energy Materials.

The development of clean energy generation, transmission, and distribution technology, for example, high energy density batteries and high efficiency solar cells, is critical to the progress toward a sustainable future. Such advancement in both scientific understanding and technological innovations entail an atomic- and molecular-resolution understanding of the key materials and fundamental processes governing the operation and failure of the systems. These dynamic processes span multiple length and time scales bridging materials and interfaces involved across the entire device architecture. However, these key components are often highly sensitive to air, moisture, and electron-beam radiation and therefore remain resistant to conventional nanoscale interrogation by electron-optical methods, such as high-resolution (scanning) transmission electron microscopy and spectroscopy.Fortunately, the rapid progress in cryogenic electron microscopy (cryo-EM) for physical sciences starts to offer researchers new tools and methods to probe these otherwise inaccessible length scales of components and phenomena in energy science. Specifically, weakly bonded and reactive materials, interfaces and phases that typically degrade under high energy electron-beam irradiation and environmental exposure can potentially be protected and stabilized by cryogenic methods, bringing up thrilling opportunities to address many crucial yet unanswered questions in energy science, which can eventually lead to new scientific discoveries and technological breakthroughs.Thus, in this Account, we aim to highlight the significance of cryo-EM to energy related research and the impactful results that can be potentially spawned from there. Due to the limited space, we will mainly review representative examples of cryo-EM methodology for lithium (Li)-based batteries, hybrid perovskite solar cells, and metal-organic-frameworks, which have shown great promise in revealing atomic resolution of both structural and chemical information on the sensitive yet critical components in these systems. We will first emphasize the application of cryo-EM to resolve the nanostructure and chemistry of solid-electrolyte interphases, cathode-electrolyte interphase, and electrode materials in batteries to reflect how cryo-EM could inspire rational materials design and guide battery research toward practical applications. We then discuss how cryo-EM helped to reveal guest intercalation chemistry in weakly bonded metal-organic-frameworks to develop a complete picture of host-guest interaction. Next, we summarize efforts in hybrid perovskite materials for solar cells where cryo-EM preserved the volatile organic molecules and protected perovskites from any air or moisture contamination. Finally, we conclude with perspectives and brief discussion on future directions for cryo-EM in energy and materials science.

CD44V3, an Alternatively Spliced Form of CD44, Promotes Pancreatic Cancer Progression.

Pancreatic cancer is one of the most lethal malignant tumors. However, the molecular mechanisms responsible for its progression are little known. This study aimed to understand the regulatory role of CD44V3 in pancreatic cancer. A Kaplan-Meier analysis was performed to reveal the correlation between CD44/CD44V3 expression and the prognosis of pancreatic cancer patients. CD44V3 and U2AF1 were knocked down using shRNAs. The proliferation, migration, invasion, and stemness of two pancreatic cell lines, BxPC-3 and AsPC-1, were examined. The expression of CD44V3, cancer-associated markers, and the activation of AKT signaling were detected by qRT-PCR and Western blot. Both CD44 and CD44V3 expression levels were associated with a poor prognosis in pancreatic cancer patients. Interestingly, the expression of CD44V3, instead of CD44, was greatly increased in tumor tissues. CD44V3 knockdown inhibited the proliferation, migration, invasion, and stemness of cancer cells. CD44V3 splicing was regulated by U2AF1 and downregulation of U2AF1 enhanced CD44V3 expression, which promoted pancreatic cancer progression. CD44V3 is an important cancer-promoting factor, which may serve as a potential candidate for pancreatic cancer intervention.

C-X-C chemokine receptor 2 (Cxcr2) promotes hepatocellular carcinoma immune evasion via regulating programmed death-ligand 1 (PD-L1).

Strategies to sensitize hepatocellular carcinomas (HCC) to programmed death-1 (PD1)/programmed death-ligand 1 (PD-L1) inhibitor therapies are important in improving the survival of HCC patients. The aim of the study was to characterize C-X-C chemokine receptor 2 (Cxcr2) as a therapeutic target in HCC and evaluate the effects of Cxcr2 suppression in sensitizing HCC to PD1/PD-L1 inhibitor therapies. To this end, we constructed a Cxcr2-knockout HCC cell line (Hepa1-6 KO) using the CRISPR-Cas9 approach and assessed the tumor growth rate and survival of mice after subcutaneously inoculating Hepa1-6 KO cells in mice. We show that Cxcr2 knockdown does not dramatically inhibit tumor growth and improve mouse survival. In tumor xenografts, the proportion of T cells is not affected but the ratio of M1/M2 macrophage is greatly increased. Cxcr2 knockdown does not alter cell viability but macrophages co-cultured with Hepa1-6 KO cells are shifted to M1 phenotypes compared to WT cells. Hepa-1-6 KO cells exhibit lower levels of PD-L1 expression. c-Myc is suppressed in Hepa1-6 KO cells, which contributes to PD-L1 downregulation. Knockdown of Cxcr2 decreases PD-L1 levels and consequently promotes the shift of macrophages to the M1 phenotype, which is mediated by downregulating c-Myc. In summary, Cxcr2 is a potential target for suppressing immune escape in HCC.

Trends in mica-mica adhesion reflect the influence of molecular details on long-range dispersion forces underlying aggregation and coalignment.

Oriented attachment of nanocrystalline subunits is recognized as a common crystallization pathway that is closely related to formation of nanoparticle superlattices, mesocrystals, and other kinetically stabilized structures. Approaching particles have been observed to rotate to achieve coalignment while separated by nanometer-scale solvent layers. Little is known about the forces that drive coalignment, particularly in this "solvent-separated" regime. To obtain a mechanistic understanding of this process, we used atomic-force-microscopy-based dynamic force spectroscopy with tips fabricated from oriented mica to measure the adhesion forces between mica (001) surfaces in electrolyte solutions as a function of orientation, temperature, electrolyte type, and electrolyte concentration. The results reveal an ∼60° periodicity as well as a complex dependence on electrolyte concentration and temperature. A continuum model that considers the competition between electrostatic repulsion and van der Waals attraction, augmented by microscopic details that include surface separation, water structure, ion hydration, and charge regulation at the interface, qualitatively reproduces the observed trends and implies that dispersion forces are responsible for establishing coalignment in the solvent-separated state.

Genetic polymorphism of 17 Y chromosomal STRs in Kazakh and Uighur populations from Xinjiang, China.

To evaluate the utility of Y-STR data for DNA testing in two ethnic populations of Xinjiang province, a sample of 338 subjects (121 Kazakhs and 217 Uighurs) was tested. In the Kazakh and Uighur populations, the haplotype diversity was 0.868 and 0.996, respectively, and the discrimination capacity was 0.5950 and 0.8940, respectively. High numbers of singleton haplotypes were observed among Xinjiang Uighurs, but fewer were found in Kazakhs. Our results were also compared with geographically and linguistically close populations.

A sulfur-modified pore-blocking method to enhance the electrocatalytic stability of carbon-supported platinum nanoparticles.

Currently, the durability of electrode materials remains a big obstacle to the widespread adoption of proton exchange membrane fuel cells (PEMFCs). Herein thiourea and sodium dodecyl benzene sulfonate (SDS) were employed as sulfur source and carbon source to modify the pristine carbon black (Ketjen black EC300 J). A highly durable carbon supported Pt nanosized catalyst with higher platinum utilization for oxygen reduction reaction (ORR) in PEMFCs was produced by doping elemental sulfur into carbon supports and decreasing the carbon pore sizes and volume through a successive impregnation technique. The catalyst exhibits an initial activity of 0.167 A mgPt -1 at 0.90 V and demonstrates minimal activity loss after acceleration stress test (30,000 cycles of AST). The half-wave potential loss for representative sample (Pt/S-C-3) is only 14 mV with only 21.8 % ECSA decrease, 27.5 % MA loss and 5.9 % SA loss. A sintering test at various temperature shows a minor average size increase for sulfur-doped carbon (S-C) supported one (from 2.09 to 2.52 nm). In single-cell test, the MEA sample employing the platinum catalyst on modified carbon as cathode exhibited almost negligible performance loss after 30,000 cycles of AST.

Portsite metastasis of adenocarcinoma after laparoscopic cholecystectomy with an unknown primary tumor: a case report.

Port site metastasis of adenocarcinoma after laparoscopic cholecystectomy with an unknown primary tumor is rare. To the best of our knowledge, there are only four such cases reported worldwide. We report a woman in her 70s with cholecystitis who underwent laparoscopic cholecystectomy. Intraoperative laparoscopic exploration did not reveal an abdominal tumor, and postoperative gallbladder pathology did not suggest malignancy. However, 11 months later, she developed an incisional mass in the epigastric port site. In another 6 months, magnetic resonance imaging revealed an abdominal wall tumor. Therefore, she underwent radical resection of the subcutaneous tumor, and postoperative pathology revealed adenocarcinoma. However, no primary tumor was found after systemic imaging examination.

Duodenal stenosis caused by locally advanced upper tract urothelial carcinoma: a case report.

Duodenal stenosis caused by upper tract urothelial carcinoma (UTUC) is rare. A 70-year-old male patient was diagnosed with a UTUC invading the duodenum 3 months before admission. Owing to duodenal stenosis, enteral nutrition was necessary. We performed pancreaticoduodenectomy with right nephroureterectomy and right hemicolectomy using a multi-disciplinary approach. Postoperative pathology revealed a UTUC invading the right kidney, duodenum, pancreas, and transverse colon. The patient underwent chemotherapy and immunotherapy after surgery, which improved his quality of life.

Structure and composition of natural ferrihydrite nano-colloids in anoxic groundwater.

Fe-rich mobile colloids play vital yet poorly understood roles in the biogeochemical cycling of Fe in groundwater by influencing organic matter (OM) preservation and fluxes of Fe, OM, and other essential (micro-)nutrients. Yet, few studies have provided molecular detail on the structures and compositions of Fe-rich mobile colloids and factors controlling their persistence in natural groundwater. Here, we provide comprehensive new information on the sizes, molecular structures, and compositions of Fe-rich mobile colloids that accounted for up to 72% of aqueous Fe in anoxic groundwater from a redox-active floodplain. The mobile colloids are multi-phase assemblages consisting of Si-coated ferrihydrite nanoparticles and Fe(II)-OM complexes. Ferrihydrite nanoparticles persisted under both oxic and anoxic conditions, which we attribute to passivation by Si and OM. These findings suggest that mobile Fe-rich colloids generated in floodplains can persist during transport through redox-variable soils and could be discharged to surface waters. These results shed new light on their potential to transport Fe, OM, and nutrients across terrestrial-aquatic interfaces.

Evaluation Method of Comprehensive Quality of Environmental Protection Teachers Based on Big Data Analysis Technology.

In order to improve the shortcomings that the weight of each index is easily affected by human influence in the evaluation of traditional teachers' comprehensive literacy, on the basis of the analysis of index coefficients, feature reorganization, and feature analysis, this paper constructs the comprehensive literacy of environmental protection professional teachers' education in the big data environment. The evaluation model is proposed, and a weight distribution scheme for teachers' comprehensive literacy evaluation indicators is proposed based on the hierarchical Bayesian beta-return model, so as to improve the rationality of the indicator distribution and make the prediction results more accurate. The simulation results further verify the superiority of the proposed model in improving the comprehensive quality evaluation level of environmental protection teachers.

Electron crystallography of chiral and non-chiral small molecules.

Electron crystallography has recently gained attentions in multiple fields of research, as it has been demonstrated to determine atomic structures for inorganic, organic, and macromolecular materials from nano-sized crystals that were not amenable to conventional X-ray crystallography. Here, we demonstrate continuous-rotation microcrystal electron diffraction (microED) in a 200 kV transmission electron microscope using a DE-64 camera-a low-noise direct electron detector that can accommodate a linear response up to ∼1200 electrons per pixel per second at 20 fps with 2x-hardware-binning, making it ideal for acquisition of high-quality diffraction patterns. We have used this method and camera to determine a 0.75 Å structure of an organic molecule, biotin, with an exceptional goodness-of-fit, as well as a 0.88 Å structure of a chiral molecule, L-serine.

Clear Cell Renal Cell Carcinoma Metastasized to the Ampulla of Vater 16 Years after Nephrectomy-A Rare Case.

Although clear cell renal cell carcinoma (ccRCC) is easy to diagnose early and most can be radically resected, nearly one-third of patients still experience metastases after radical nephrectomy. The most common distant metastases sites of ccRCC are lung, bone and liver. However, periampullary metastasis of ccRCC is very rare and easy to misdiagnose. A 59-year-old male patient was hospitalized for recurrent hematochezia. He had a history of nephrectomy 16 years ago due to ccRCC. Enhanced upper abdominal computed tomography (CT) suggested a mass in the ampulla of vater, and active hemorrhage of duodenal papilla was observed by endoscopy. He underwent an emergency pancreaticoduodenectomy because endoscopic hemostasis and transcatheter arterial embolization (TAE) both failed. Intraoperatively, we found that the tumor located in the ampulla and invaded the pancreatic tissue. The operation was successful, with no postoperative complications. Postoperative pathology suggested metastatic ccRCC.

Light-activatable multifunctional paclitaxel nanoprodrug for synergistic chemo-photodynamic therapy in liver cancer.

Paclitaxel (Ptx) is widely utilized to treat liver cancer, and the treatment benefit of reactive oxygen species (ROS)-responsive Ptx nanoprodrug is investigated in this study. The one-step nano-precipitation method was utilized to self-assembly DSPE-PEG2000 -thioketal linker (TK)-Ptx with pyropheophorbide acid nanoparticles (PPa NPs) to form PPa/Ptx NPs. Dynamic light scattering and transmission electron microscopy were used for characterization, and 2'-7'dichlorofluorescin diacetate staining was utilized for intracellular ROS detection. HepG2 cells viability and tumor growth rate of HepG2 bearing mice were assayed. Hematoxylin and eosin staining, proliferating cell nuclear antigen detection, and terminal deoxynucleotidyl transferase dUTP nick-end labeling assay were utilized for histology assessment. PPa/Ptx NPs incubation with light irradiation showed superior cytotoxicity to HepG2 cells with increased intracellular ROS production than PPa/Ptx NPs incubation without light irradiation or PPa NPs incubation with light irradiation. At the same time, PPa/Ptx NPs with light irradiation could significantly decrease the tumor growth in vivo as indicated by diminished tumor volume with the largest necrotic area, the highest rate of apoptotic cells, and the least proliferating cells. PPa/Ptx NPs show synergistic chemo-photodynamic characteristics, which could be considered as a promising treatment option for liver cancer.

Capturing the swelling of solid-electrolyte interphase in lithium metal batteries.

Although liquid-solid interfaces are foundational in broad areas of science, characterizing this delicate interface remains inherently difficult because of shortcomings in existing tools to access liquid and solid phases simultaneously at the nanoscale. This leads to substantial gaps in our understanding of the structure and chemistry of key interfaces in battery systems. We adopt and modify a thin film vitrification method to preserve the sensitive yet critical interfaces in batteries at native liquid electrolyte environments to enable cryo­electron microscopy and spectroscopy. We report substantial swelling of the solid-electrolyte interphase (SEI) on lithium metal anode in various electrolytes. The swelling behavior is dependent on electrolyte chemistry and is highly correlated to battery performance. Higher degrees of SEI swelling tend to exhibit poor electrochemical cycling.

Multiple episodes of postpancreatectomy hemorrhage resolved by endoscopy and ultrasound-guided percutaneous thrombin injection into a common hepatic artery aneurysm: a case report.

Postpancreatectomy hemorrhage (PPH) is one of the most common complications after pancreatoduodenectomy (PD). It mainly includes gastrointestinal hemorrhage and abdominal hemorrhage. With the development of digestive endoscopy and ultrasonic/radiological interventional technology, hemostasis can be effectively performed by minimally invasive methods in many patients with PPH. This report describes the successful treatment of multiple episodes of postoperative hemorrhage after PD. The patient developed anastomotic hemorrhage after PD and was successfully treated by endoscopic hemostasis. However, he also developed intra-abdominal hemorrhage after PD caused by a pseudoaneurysm that had formed next to the common hepatic artery. We effectively performed hemostasis by injecting lyophilized thrombin powder into the pseudoaneurysm with ultrasound guidance, which is a rarely used method. This case indicates that digestive endoscopy provides great advantages in the treatment of gastrointestinal hemorrhage after PD. For patients who develop PPH with a pseudoaneurysm, interventional ultrasonography is an option if transcatheter arterial embolization or covered stenting fails.

Downregulation of orosomucoid 2 acts as a prognostic factor associated with cancer-promoting pathways in liver cancer.

BACKGROUND: Liver cancer has a high mortality and morbidity rate throughout the world. In clinical practice, the prognosis of liver cancer patients is poor, and the complex reasons contribute to treatment failures, including fibrosis, hepatitis viral infection, drug resistance and metastasis. Thus, screening novel prognostic biomarkers is of great importance for guiding liver cancer therapy. Orosomucoid genes (ORMs) encode acute phase plasma proteins, including orosomucoid 1 (ORM1) and ORM2. Previous studies showed their upregulation upon inflammation, but the specific function of ORMs has not yet been determined, especially in the development of liver cancer. AIM: To determine the expression of ORMs and their potential function in liver cancer. METHODS: Analysis of the expression of ORMs in different human tissues was performed on data from the HPA RNA-seq normal tissues project. The expression ratio of ORMs was determined using the HCCDB database, including the ratio between liver cancer and other cancers, normal liver and other normal tissues, liver cancer and adjacent normal liver tissues. Analysis of ORM expression in different cancer types was performed using The Cancer Genome Atlas and TIMER database. The expression of ORMs in liver tumor tissues and adjacent normal tissues were further confirmed using Gene Expression Omnibus data, including GSE36376 and GSE14520. The 10-year overall survival (OS), progression-free survival (PFS) and relapse-free survival (RFS) rates between high and low ORM expression groups in liver cancer patients were determined using the Kaplan-Meier plotter tool. Gene Set Enrichment Analysis (GSEA) was employed to explore the ORM2-associated signaling network. Correlations between ORM2 expression and tumor purity or the infiltration level of macrophages in liver tumor tissues were determined using the TIMER database. The correlation between ORM2 gene levels, tumor-associated macrophage (TAM) markers (including CD68 and TGFß1) and T cell immunosuppression (including CTLA4 and PD-1) in liver tumor tissues and liver GTEx was determined using the GEPIA database. RESULTS: ORM1 and ORM2 were highly expressed in normal liver and liver tumor tissues. ORM1 and ORM2 expression was significantly decreased in liver tumor tissues compared with adjacent normal tissues, and similar results were also noted in cholangiocarcinoma, esophageal carcinoma, and lung squamous cell carcinoma. Further analysis of the Gene Expression Omnibus Database also confirmed the downregulation of ORM1 and ORM2 in liver tumors. Survival analysis showed that the high ORM2 group had better survival rates in OS, PFS and RFS. ORM1 only represented better performance in PFS, but not in OS or RFS. GSEA analysis of ORM2 from The Cancer Genome Atlas liver cancer data identified that ORM2 positively associated with the G2/M checkpoint, E2F target signaling, as well as Wnt/ß-catenin and Hedgehog signaling. Moreover, apoptosis, IFN-α responses, IFN-γ responses and humoral immune responses were upregulated in the ORM2 high group. ORM2 expression was negatively correlated with the macrophage infiltration level, CD68, TGFß1, CTLA4 and PD-1 levels. CONCLUSION: The results showed that ORM1 and ORM2 were highly expressed specifically in liver tissues, whereas ORM1 and ORM2 were downregulated in liver tumor tissues. ORM2 is a better prognostic factor for liver cancer. Furthermore, ORM2 is closely associated with cancer-promoting pathways.

Cryo-EM structures of atomic surfaces and host-guest chemistry in metal-organic frameworks.

Host-guest interactions govern the chemistry of a broad range of functional materials, but direct imaging using conventional transmission electron microscopy (TEM) has not been possible. This problem is exacerbated in metal-organic framework (MOF) materials, which are easily damaged by the electron beam. Here, we use cryogenic-electron microscopy (cryo-EM) to stabilize the host-guest structure and resolve the atomic surface of zeolitic imidazolate framework (ZIF-8) and its interaction with guest CO2 molecules. We image step-edge sites on the ZIF-8 surface that provides insight to its growth behavior. Furthermore, we observe two distinct binding sites for CO2 within the ZIF-8 pore, which are predicted by density functional theory (DFT) to be energetically favorable. This CO2 insertion induces an apparent ~3% lattice expansion along the <002> and <011> directions of the ZIF-8 unit cell. The ability to stabilize and preserve host-guest chemistry opens a rich materials space for scientific exploration and discovery using cryo-EM.

Unravelling Atomic Structure and Degradation Mechanisms of Organic-Inorganic Halide Perovskites by Cryo-EM.

Despite rapid progress of hybrid organic-inorganic halide perovskite solar cells, using transmission electron microscopy to study their atomic structures has not been possible because of their extreme sensitivity to electron beam irradiation and environmental exposure. Here, we develop cryogenic-electron microscopy (cryo-EM) protocols to preserve an extremely sensitive perovskite, methylammonium lead iodide (MAPbI3) under various operating conditions for atomic-resolution imaging. We discover the precipitation of lead iodide nanoparticles on MAPbI3 nanowire's surface after short UV illumination and surface roughening after only 10 s exposure to air, while these effects remain undetected in conventional x-ray diffraction. We establish a definition for critical electron dose, and find this value for MAPbI3 at cryogenic condition to be 12 e-/Å2 at 1.49 Å spatial resolution. Our results highlight the importance of cryo-EM since traditional techniques cannot capture important nanoscale changes in morphology and structure that have important implications for perovskite solar cell stability and performance.