Highly stable Pt-Co bimetallic catalysts prepared by atomic layer deposition for selective hydrogenation of cinnamaldehyde

Pt-Co bimetallic catalysts were deposited onγ-Al₂O₃nanoparticles by atomic layer deposition (ALD) and were used for selective hydrogenation of cinnamaldehyde (CAL) to cinnamyl alcohol (COL). High resolution transmission electron microscopy, hydrogen temperature-programmed reduction, x-ray diffraction, and x-ray photoelectron spectroscopy were used to identify the strong interaction between Pt and Co. The obtained catalysts with an optimal Pt/Co ratio achieved a COL selectivity of 81.2% with a CAL conversion of 95.2% under mild conditions (i.e., 10 bar H₂and 80 °C). During the CAL hydrogenation, the addition of Co on Pt significantly improved the activity and selectivity due to the synergetic effects of Pt-Co bimetallic catalysts, resulted from the transfer of electrons from Co to Pt, which can stabilize the carbonyl groups. The obtained Pt-Co bimetallic catalysts also showed excellent stability due to the strong interaction between the metal nanoparticles and the alumina support. Negligible losses in the activity and selectivity were observed during the recycling experiments, showing the potential for practical applications.

AlF3-Al2O3 ALD Thin-Film-Coated Li1.2Mn0.54Co0.13Ni0.13O2 Particles for Lithium-Ion Batteries: Long-Term Protection

Improving the performance of existing cathode materials of lithium-ion batteries (LIBs) through surface modification has been proven to be an effective way to improve the performance of LIBs. However, it is a challenge to use a traditional method to prepare an effective coating film, which meets the requirements of uniformity, continuity, electrochemical stability, and strong mechanical properties. In this study, an ultrathin AlF₃-Al₂O₃ film was coated on the surface of Li_1.2Mn_0.54Co_0.13Ni_0.13O₂ (LRNMC) particles by atomic layer deposition (ALD) in a fluidized bed reactor. A cathode electrolyte interphase layer mainly composed of inorganic components was formed on the surface of AlF₃-Al₂O₃-coated LRNMC during the charge/discharge cycling process, which led to the enhancement of capacity and cycling stability. In addition, the coating layer significantly increased the shelf life of the cathode particles. For LRNMC particles with one cycle of Al₂O₃ ALD and one cycle of AlF₃ ALD coatings, there was no obvious degradation of electrochemical performance after being stored for more than 1 year, indicating long-term protection of ALD films for LIB cathode particles.

Improving the Comprehensive Performance of Na0.7MnO2 for Sodium Ion Batteries by ZrO2 Atomic Layer Deposition

Sodium ion batteries with Na-Mn-O compounds as cathodes have been widely studied as substitutes for lithium ion batteries due to their abundant resources. However, the relatively poor cycling stability and low capacity of Na-Mn-O compounds significantly limit their applications. Different approaches, including element substitution and surface modification, have been applied to improve the electrochemical performance of those cathode materials. Herein, element doping and coating of ZrO₂ on Na_0.7MnO₂ particles have been achieved by atomic layer deposition followed by post-annealing. The rate capability and cycling stability of the modified materials were significantly improved, and the mechanism of performance enhancement was revealed. The ZrO₂ coatings acted as a stable interfacial layer to enhance the cycling stability of Na_0.7MnO₂ by suppressing side reactions between the electrode and electrolyte. The doping of transition metal ions reduced energy barriers for sodium ion insertion and deintercalation during charge/discharge cycling, further improving the charge/discharge capacity and rate performance of Na_0.7MnO₂.

Solvent-Free Solid-State Lithium Battery Based on LiFePO4 and MWCNT/PEO/PVDF-HFP for High-Temperature Applications

Rechargeable lithium-ion batteries (LIBs) have a wide range of applications but face challenges in harsh working or operating environments at high temperatures. In this work, a solid polymer electrolyte with MWCNT-COOH as an additive (MWCNT-SPE) was obtained. MWCNT-SPE has a high thermal stability and can be used in high-temperature operating environments. Solid-state lithium batteries based on MWCNT-SPE and LiFePO₄ were assembled. The resulting lithium batteries exhibited excellent electrochemical properties at 70 and 120 °C, demonstrating a wide range of operations suitable for solid-state batteries with extreme demands. The symmetrical Li/MWCNT-SPE/Li cell operated for 1800 h with low polarization voltage and no short circuit, and the LiFePO₄/MWCNT-SPE/Li cell delivered superior cycling performance under both 0.2 and 0.5 C-rates, indicating that the interface compatibility between the lithium metal and MWCNT-SPE membrane was good and could effectively suppress the formation of lithium dendrites. The superior performance of the resulting MWCNT-SPE was due to the weak interaction between PEO, PVDF-HFP, and MWCNT-COOH, which reduced the tendency of PEO's crystallinity and thereby significantly increased the Li⁺ migration ability and improved the cycling life of the batteries.

LOXL2-enriched small extracellular vesicles mediate hypoxia-induced premetastatic niche and indicates poor outcome of head and neck cancer

Small extracellular vesicles (sEVs) operate as a signaling platform due to their ability to carry functional molecular cargos. However, the role of sEVs in hypoxic tumor microenvironment-mediated premetastatic niche formation remains poorly understood. Methods: Protein expression profile of sEVs derived from normoxic and hypoxic head and neck squamous cell carcinoma (HNSCC) cells were determined by Isobaric Tagging Technology for Relative Quantitation. In vitro invasion assay and in vivo colonization were performed to evaluate the role of sEV-delivering proteins. Results: We identified lysyl oxidase like 2 (LOXL2) which had the highest fold increase in hypoxic sEVs compared with normoxic sEVs. Hypoxic cell-derived sEVs delivered high amounts of LOXL2 to non-hypoxic HNSCC cells to elicit epithelial-to-mesenchymal transition (EMT) and induce the invasion of the recipient cancer cells. Moreover, LOXL2-enriched sEVs were incorporated by distant fibroblasts and activate FAK/Src signaling in recipient fibroblasts. Increased production of fibronectin mediated by FAK/Src signaling recruited myeloid-derived suppressor cells to form a premetastatic niche. Serum sEV LOXL2 can reflect a hypoxic and aggressive tumor type and can serve as an alternative to tissue LOXL2 as an independent prognostic factor of overall survival for patients with HNSCC. Conclusion: sEVs derived from the hypoxic tumor microenvironment of HNSCC can drive local invasion of non-hypoxic HNSCC cells and stimulate premetastatic niche formation by delivering LOXL2 to non-hypoxic HNSCC cells and fibroblasts to induce EMT and fibronectin production, respectively.

Insight Into the Molecular Mechanism of Podophyllotoxin Derivatives as Anticancer Drugs

Podophyllotoxin (PTOX) is a biologically active compound derived from the podophyllum plant, and both it and its derivatives possess excellent antitumor activity. The PTOX derivatives etoposide (VP-16) and teniposide (VM-26) have been approved by the U.S. Food and Drug Administration (FDA) for cancer treatment, but are far from perfect. Hence, numerous PTOX derivatives have been developed to address the major limitations of PTOX, such as systemic toxicity, drug resistance, and low bioavailability. Regarding their anticancer mechanism, extensive studies have revealed that PTOX derivatives can induce cell cycle G2/M arrest and DNA/RNA breaks by targeting tubulin and topoisomerase II, respectively. However, few studies are dedicated to exploring the interactions between PTOX derivatives and downstream cancer-related signaling pathways, which is reasonably important for gaining insight into the role of PTOX. This review provides a comprehensive analysis of the role of PTOX derivatives in the biological behavior of tumors and potential molecular signaling pathways, aiming to help researchers design and develop better PTOX derivatives.

Transcriptomic analyses reveal dynamic changes of defense response in Glycyrrhiza uralensis leaves under enhanced ultraviolet-B radiation

The amount of solar ultraviolet-B (UV-B) radiation reaching the Earth's surface is increasing due to stratospheric ozone dynamics and global climate change. Increased UV-B radiation poses a major threat to ecosystems. Although many studies have focused on the potential effects of enhanced UV-B radiation on plants, the dynamic changes of defense response in plants under continuous UV-B radiation remains enigmatic. In this study, we investigated the effect of UV-B radiation at 0.024 W/m² on the UVR8-and reactive oxygen species (ROS-) signaling pathways, antioxidant system, and wax synthesis of G. uralensis. These parameters were investigated at different UV-B radiation stages (2 h, 6 h, 12 h, 24 h, 48 h, and 96 h). The results revealed that the uvr8 expression level was significantly repressed after 2 h of UV-B radiation, partly because G. uralensis rapidly acclimated to UV-B. Significant H₂O₂ accumulation occurred after 12 h UV-B radiation, resulting in activation of the ROS signaling pathway and the antioxidant system. After 24 h of UV-B radiation, wax synthesis was enhanced alongside a decrease in the capacity of the main antioxidant system. The dynamic and ordered changes in these pathways reveal how different strategies function in G. uralensis at different times during adaption to enhanced UV-B radiation. This study will help us better understand dynamic changes of defense response in plant under enhanced UV-B radiation, further providing fundamental knowledge to develop plant resistance gene resources.

Clinical and CT features of mild-to-moderate COVID-19 cases after two sequential negative nucleic acid testing results: a retrospective analysis

Background

The clinical and imaging features of patients with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections that progressed to coronavirus disease 2019 (COVID-19) have been explored in numerous studies. However, little is known about these features in patients who received negative respiratory nucleic acid test results after the infections resolved. In this study, we aim to describe these features in a group of Chinese patients.

Methods

This retrospective study includes 51 patients with mild-to-moderate COVID-19 (median age: 34.0 years and 47.1% male) between January 31 and February 28, 2020. Demographic, clinical, laboratory, and computed tomography (CT) imaging data were collected before and after two consecutive negative respiratory SARS-CoV-2 tests.

Results

Following a negative test result, the patients’ clinical symptoms continued to recover, but abnormal imaging findings were observed in all moderate cases. Specifically, 77.4% of patients with moderate COVID-19 exhibited multi-lobar lung involvement and lesions were more frequently observed in the lower lobes. The most common CT imaging manifestations were ground-glass opacities (51.6%) and fibrous stripes (54.8%%). Twelve of the 31 patients with moderate COVID-19 underwent repeated chest CT scans after a negative SARS-CoV-2 test. Among them, the ground-glass opacities decreased by > 60% within 1 week in seven patients (58.3%), but by < 5% in four patients (13.8%).

Conclusions

Following a positive and subsequent negative SARS-CoV-2 tests, patients with COVID-19 continued to recover despite exhibiting persistent clinical symptoms and abnormal imaging findings.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12879-021-06013-x.

Fibroblasts in cancer dormancy: foe or friend?

Cancer dormancy is defined that the residual cancer cells could enter into a state of quiescence and patients remain asymptomatic for years or even decades after anti-tumor therapies. Fibroblasts, which represent a predominant cell type in tumor microenvironment, play a pivotal role in determining the ultimate fate of tumor cells. This review recapitulates the pleiotropic roles of fibroblasts which are divided into normal, senescent, cancer-associated fibroblasts (CAFs) and circulation CAFs in tumor dormancy, relapse, metastasis and resistance to therapy to help the treatment of cancer metastasis.

Correlation of the ratio of IgM/IgG concentration to days after symptom onset (IgM/T or IgG/T) with disease severity and outcome in non-critical COVID-19 patients

BACKGROUND

Correlation of SARS-CoV-2 serum antibodies with COVID-19 development and outcome has not been fully studied. Due to the time dynamic of antibodies, the antibody concentration of the same patient varies greatly at different times during the course of the disease. Therefore, our study used IgM/T or IgG/T (the ratio of serum antibody concentration to days after symptom onset) to reflect the patient's humoral immune status, and analyzed their correlation with COVID-19 development and outcome.

METHODS

Clinical data of 50 non-critical COVID-19 patients were retrospectively analyzed. Time-resolved fluorescence immunochromatography was used to quantitatively detect SARS-CoV-2 IgM and IgG. Correlation analysis was performed.

RESULTS

IgM antibody was positive on day 5 of symptom onset, increased within 2 weeks, and then gradually decreased. However, IgG antibody was positive on week 2 of symptom onset and continued to increase since. Additionally, IgM/T, but not IgG/T of recovery period (Spearman ρ=0.17; P=0.283), was negatively correlated with disease course in 2 weeks of symptom onset (Spearman ρ=-0.860; P=0.000). IgG/T of recovery period was positively correlated with clinical classification (Spearman ρ=0.432; P=0.004), number of involved lung lobes (Spearman ρ=0.343; P=0.026), and lung lesions (Spearman ρ=0.472; P=0.002).

CONCLUSIONS

Within 2 weeks of symptom onset, higher IgM/T indicates faster recovery and shorter disease course. In recovery period, higher IgG/T suggests more serious disease. IgM/T or IgG/T may predict disease severity and outcome in non-critical COVID-19 patients.

Small extracellular vesicles containing miR-192/215 mediate hypoxia-induced cancer-associated fibroblast development in head and neck squamous cell carcinoma

The mechanisms underlying the hypoxic cancer cell-mediated differentiation of cancer-associated fibroblasts (CAFs) have not been elucidated yet. The present study showed that the hypoxic head and neck squamous cell carcinoma (HNSCC) cells promoted CAF-like differentiation through secreting TGF-β and small extracellular vesicles (sEVs) that contain enhanced levels of miR-192/215 family miRNAs. Caveolin-1 (CAV1), which is a target gene of miR-192/215, inhibited the TGF-β/SMAD signaling and promoted CAF-like differentiation of the fibroblasts. Restoring the levels of CAV1 inhibited the hypoxic sEV- and TGF-β-induced CAF-like differentiation. The enhanced levels of miR-192/215 encapsulated in the HNSCC tissue-derived sEVs (but not serum-derived sEVs) indicated hypoxic and aggressive cancer stroma. miR-215 in the tumor tissue-derived sEVs (but not circulating sEVs) was correlated with poor overall survival of patients with HNSCC. This study demonstrated that sEVs function as a "courier" to deliver miRNAs from the cancer cells to the fibroblasts, which promotes the remodeling of the hypoxic tumor microenvironment, and that cancer tissue-derived sEV could potentially serve as a source of biomarker.

Pt–Carbon interaction-determined reaction pathway and selectivity for hydrogenation of 5-hydroxymethylfurfural over carbon supported Pt catalysts

In the hydrogenation of HMF, the main product was DHMF over all carbon supported Pt catalysts prepared by impregnation, and it changed to DMF over the Pt catalysts prepared via atomic layer deposition due to the relatively strong Pt–CNT interaction.

Simple Approach: Heat Treatment to Improve the Electrochemical Performance of Commonly Used Anode Electrodes for Lithium-Ion Batteries

The lithium-ion battery (LIB) industry has been in high demand for simple and effective methods to improve the electrochemical performance of LIBs. Here, we treated three different widely studied anode electrodes (i.e., Li₄Ti₅O₁₂, TiO₂, and graphite) under vacuum at 250 °C, and compared their electrochemical performance with and without a 250 °C treatment. Without changing the composition of the fabricated electrodes, all of the 250 °C treated electrodes exhibited enhanced specific capacities, and the lithium-ion diffusion was improved in different degrees. By comparing the results of scanning electron microscopy (SEM) and energy-dispersive spectroscopy of the pristine and 250 °C treated electrodes, the 250 °C treatment improved the distribution of a polyvinylidene difluoride (PVDF) binder in the electrodes, resulting in a higher porosity of the 250 °C treated electrodes. The results of X-ray photoelectron spectrometry and SEM of the cycled electrodes confirmed that a uniform distribution of the PVDF binder from the 250 °C treatment played a positive role in the formation of a solid electrolyte interphase layer, thereby delivering higher capacities and capacity retentions than those of electrodes without heat treatment. The simplicity of this modification method provides considerable potential for building high-performance LIBs at a larger scale.

Atomic Layer Deposited Ni/ZrO2-SiO2 for Combined Capture and Oxidation of VOCs

This work reports on the development of novel Ni nanoparticle-deposited mixed-metal oxides ZrO₂-SiO₂ through atomic layer deposition (ALD) method and their application in combined capture and oxidation of benzene, as a model compound of aromatic VOCs. Concentrating ppm-level VOCs in situ, before their oxidation, offers a practical approach to reduce the catalyst inventory and capital cost associated with VOC emissions abatement. The benzene vapor adsorption isotherms were measured at 25 °C and in the pressure range of 0 to benzene saturation vapor pressure thereof (0.13 bar). In the combined capture-reaction tests, the materials were first exposed to ca. 86 100 ppm_v benzene vapor at 25 °C, followed by desorption and catalytic oxidation while raising the bed temperature to 250 °C. The textural properties revealed that ALD of Ni or ZrO₂ on SiO₂ decreased surface area and pore volume, while sequential doping with ZrO₂ and then Ni caused the otherwise. The benzene vapor adsorption isotherms followed the type-IV isotherm classification, revealing a combination of monolayer-multilayer and capillary condensation adsorption mechanisms in sequence. At saturation vapor pressure, an average equilibrium adsorption capacity of 15 mmol/g was obtained across the materials. However, the dynamic adsorption capacities were up to 50% less than the corresponding equilibrium uptake for the materials. Benzene desorption temperature was observed around 90 °C, and conversion of 85-95% and TOF of 1.28-16.42 mmol_C6H6/mol_Ni/s were obtained over the materials, with 3Ni/ZrO₂-SiO₂, prepared with 3 ALD cycles, exhibiting the maximum conversion and TOF indicating synergistic effects of Ni nanoparticles and ZrO₂ support based on the number of ALD cycles. However, the yields of CO₂ and H₂O were about 5% and 40%, respectively. The small value of the CO₂ yield was hypothesized to be due to simultaneous high-temperature adsorption of CO₂ as the catalytic reaction progressed. The high adsorption affinity, low desorption temperature, and high catalytic activity of the materials investigated in this study made these materials as promising candidates for the abatement of BTX.

Clinical characteristics and risk factors of mild-to-moderate COVID-19 patients with false-negative SARS-CoV-2 nucleic acid

This study investigates the clinical and imaging characteristics of coronavirus disease 2019 (COVID-19) patients with false-negative nucleic acids. Mild-to-moderate COVID-19 patients, including 19 cases of nucleic acid false-negative patients and 31 cases of nucleic acid positive patients, were enrolled. Their epidemiological, clinical, and laboratory examination data and imaging characteristics were analyzed. Risk factors for false negatives were discussed. Compared with the nucleic acid positive group, the false-negative group had less epidemiological exposure (52.6% vs 83.9%; P  = .025), less chest discomfort (5.3% vs 32.3%; P  = .035), and faster recovery (10 [8, 13] vs 15 [11, 18.5] days; P  = .005). The number of involved lung lobes was (2 [1, 2.5] vs 3 [2, 4] days; P  = .004), and the lung damage severity score was (3 [2.5, 4.5] vs 5 [4, 9] days; P  = .007), which was lighter in the nucleic acid false-negative group. Thus, the absence of epidemiological exposure may be a potential risk factor for false-negative nucleic acids. The false-negative cases of COVID-19 are worth noting because they have a risk of viral transmission without positive test results, lighter clinical manifestations, and less history of epidemiological exposure.

Na+-gated water-conducting nanochannels for boosting CO2 conversion to liquid fuels

Robust, gas-impeding water-conduction nanochannels that can sieve water from small gas molecules such as hydrogen (H₂), particularly at high temperature and pressure, are desirable for boosting many important reactions severely restricted by water (the major by-product) both thermodynamically and kinetically. Identifying and constructing such nanochannels into large-area separation membranes without introducing extra defects is challenging. We found that sodium ion (Na⁺)-gated water-conduction nanochannels could be created by assembling NaA zeolite crystals into a continuous, defect-free separation membrane through a rationally designed method. Highly efficient in situ water removal through water-conduction nanochannels led to a substantial increase in carbon dioxide (CO₂) conversion and methanol yield in CO₂ hydrogenation for methanol production.

Myeloid derived suppressor cells contribute to the malignant progression of oral squamous cell carcinoma

Purpose

The tumor-related myeloid derived suppressor cells (MDSCs), important immunosuppressive cells in tumor microenvironment, play an important role in the cancer progression. This study is aimed to investigate the crosstalk between MDSCs and oral squamous cell carcinoma (OSCC) cells and their role in the malignant progression of OSCC.

Methods

Immunochemistry (IHC) was used to investigate the expression of CD33 in 200 OSCC, 36 premalignant. CD33⁺ MDSCs were sorted and enriched via magnetic-activated cell sorting (MACS) from OSCC patients or health donor, and their phenotypes were identified by flow cytometry. With a co-culture system of MDSCs and OSCC, the effects of MDSCs on OSCC proliferation, apoptosis, migration invasion, epithelial-mesenchymal transition (EMT), and vasculogenic mimicry formation (VM) formation were assessed, respectively. Besides, peripheral blood mononuclear cells (PBMCs) from health donor were cultured with OSCC supernatant, the level of MDSCs and expressions of Arginase (Arg-1) and inducible nitric oxide synthase (iNOS) were measured.

Results

The number of MDSCs was increased in tumor tissues of OSCC patients, and was positively related to the T stage, pathological grade, lymph node metastasis and poor prognosis. Tumor-related MDSCs of the co-culture system promoted OSCC progression by contributing to cell proliferation, migration and invasion as well as inducing EMT and VM. In turn, OSCC cells had potential to induce MDSCs differentiation from PBMCs and increase the expression of Arg-1 and iNOS.

Conclusion

These indicated that the crosstalk between MDSCs and tumor cells facilitated the malignant progression of OSCC cells and the immune suppressive properties of MDSCs, which may provide new insights into tumor treatment on targeting tumor-associated immunosuppressive cells.