Palladium-catalysed fragmentary esterification-induced allylic alkylation of allyl carbonates and cyclic vinylogous anhydrides.

An unprecedented palladium-catalysed fragmentary esterification-induced allylic alkylation (FEAA) of cyclic vinylogous anhydrides (CVAs) and allyl carbonates has been disclosed. The protocol features broad sp3-rich scaffold tolerance, rendering highly functionalized 1,6 and 1,7-dicarbonyls in up to high yields and diastereoselectivities. Three-component FEAA is also well tolerant to generate 1,6-dicarbonyls through the addition of extra O/N-nucleophiles. Furthermore, cyclic allyl carbonate-involved FEAA provides an efficient approach for the synthesis of structurally complex medium-sized rings.

Quartz Nonadherent and Clean Exfoliation of the Heteroatom-Doped Bulk Carbon Nanotubes Array.

Vertically aligned carbon nanotubes array offers unique properties for various applications. Detaching them from the growth substrate, while preserving their vertical structure, is essential. Quartz, a cost-effective alternative to silicon wafers and metal-based substrates, can serve as both a reaction chamber and a growth substrate. However, the strong adhesive interaction with the quartz substrate remains an obstacle for further applications. Herein, we presented a simple and well-controlled exfoliation strategy assisted by the introduction of heteroatoms at root ends of a carbon nanotubes array. This strategy forms lower surface polarity of the carbon fragment to significantly reduce adhesion to the quartz substrate, which contributes to the effortless exfoliation. Furthermore, this scalable approach enables potential mass production on recyclable quartz substrates, enhancing the cost-effectiveness and efficiency. This work can establish a solid foundation for cost-competitive carbon nanotube-based technologies, offering a promising avenue for their widespread applications.

In situ TEM investigation of nucleation and crystallization of hybrid bismuth nanodiamonds.

Despite great progress in the non-classical homogeneous nucleation and crystallization theory, the heterogeneous processes of atomic nucleation and crystallization remain poorly understood. Abundant theories and experiments have demonstrated the detailed dynamics of homogeneous nucleation; however, intensive dynamic investigations on heterogeneous nucleation are still rare. In this work, in situ transmission electron microscopy (TEM) at the atomic scale was carried out with temporal resolution for heterogeneous nucleation and crystallization. The results show a reversible amorphous to crystal phase transformation that is manipulated by the size threshold effect. Moreover, the two growth pathways of Bi particles can be mainly assigned to the atomic adsorption expansion in the amorphous state and effective fusion in the crystal contact process. These interesting findings, based on a real dynamic imaging system, strongly enrich and improve our understanding of the dynamic mechanisms in the non-classical heterogeneous nucleation and crystallization theory, providing insights into designing innovative materials with controlled microstructures and desired physicochemical properties.

Enantioselective Synthesis of Ten-Membered Lactones via Palladium-Catalyzed [5 + 5] Annulation.

Ten-membered lactones are the core units of many biologically active natural products but with a great synthetic challenge. Based on the principle of vinylogy, novel types of cyclic vinylogous anhydrides have been designed as five-carbon carbonyl synthons, further applied in [5 + 5] annulation with vinylethylene carbonates under chiral palladium catalysis. This strategy features excellent regioselectivity, mild conditions, and broad substrate scope, affording a range of spiro ten-membered lactones bearing oxindole and pyrrolidinone motif in excellent yield (up to 99%) with moderate to high enantioselectivity (up to 89% ee).

Exosomal miRNAs-mediated macrophage polarization and its potential clinical application.

Macrophages are highly heterogeneous and plastic immune cells that play an important role in the fight against pathogenic microorganisms and tumor cells. After different stimuli, macrophages can polarize to the M1 phenotype to show a pro-inflammatory effect and the M2 phenotype to show an anti-inflammatory effect. The balance of macrophage polarization is highly correlated with disease progression, and therapeutic approaches to reprogram macrophages by targeting macrophage polarization are feasible. There are a large number of exosomes in tissue cells, which can transmit information between cells. In particular, microRNAs (miRNAs) in the exosomes can regulate the polarization of macrophages and further affect the progression of various diseases. At the same time, exosomes are also effective "drug" carriers, laying the foundation for the clinical application of exosomes. This review describes some pathways involved in M1/M2 macrophage polarization and the effects of miRNA carried by exosomes from different sources on the polarization of macrophages. Finally, the application prospects and challenges of exosomes/exosomal miRNAs in clinical treatment are also discussed.

Natural killer cell homing and trafficking in tissues and tumors: from biology to application.

Natural killer (NK) cells, a subgroup of innate lymphoid cells, act as the first line of defense against cancer. Although some evidence shows that NK cells can develop in secondary lymphoid tissues, NK cells develop mainly in the bone marrow (BM) and egress into the blood circulation when they mature. They then migrate to and settle down in peripheral tissues, though some special subsets home back into the BM or secondary lymphoid organs. Owing to its success in allogeneic adoptive transfer for cancer treatment and its "off-the-shelf" potential, NK cell-based immunotherapy is attracting increasing attention in the treatment of various cancers. However, insufficient infiltration of adoptively transferred NK cells limits clinical utility, especially for solid tumors. Expansion of NK cells or engineered chimeric antigen receptor (CAR) NK cells ex vivo prior to adoptive transfer by using various cytokines alters the profiles of chemokine receptors, which affects the infiltration of transferred NK cells into tumor tissue. Several factors control NK cell trafficking and homing, including cell-intrinsic factors (e.g., transcriptional factors), cell-extrinsic factors (e.g., integrins, selectins, chemokines and their corresponding receptors, signals induced by cytokines, sphingosine-1-phosphate (S1P), etc.), and the cellular microenvironment. Here, we summarize the profiles and mechanisms of NK cell homing and trafficking at steady state and during tumor development, aiming to improve NK cell-based cancer immunotherapy.

Pd-Catalyzed Tandem [5 + 2] Cycloaddition/Ring Contraction of Phthalide-Derived Alkenes and Vinylethylene Carbonates for the Construction of Benzo-[5,5]-spiroketal Lactones.

An annulation of phthalide-derived activated alkenes is initially disclosed in this work. Specifically, we have developed an unprecedented [5 + 2] cycloaddition/ring-contraction tandem process of activated tetrasubstituted alkenes derived from phthalides or butyrolactone with vinylethylene carbonates under Pd(0) catalysis. Differing from the traditional spirolactonization strategy, this method renders an efficient and mechanistically distinct approach to benzo-[5,5]-spiroketal lactones and [5,5]-spiroketal lactones bearing two vicinal tetrasubstituted centers with high diastereoselectivity.

An outstanding role of novel virus-like heterojunction nanosphere BOCO@Ag as high performance antibacterial activity agent.

The development of highly efficient photonic nanomaterials with synergistic biological effects is critical and challenging task for public hygiene health well-being and has attracted extensive interest. In this study, a type of near-infrared (NIR) driven, virus-like heterojunction was first developed for synergistic biological application. The Ag-coated Bi2CO5 nanomaterial (BOCO@Ag) demonstrated good biocompatibility, low cytotoxicity, high antibacterial activity and excellent light utilization stability. The synthesized BOCO@Ag performed a potential high photothermal conversion (efficiency~46.81%) to generate high temperatures when irradiated with near-infrared light illumination. As expected, compared to single Ag+ disinfection, BOCO@Ag can exhibit better antibacterial performance when combined with photothermal energy and released Ag+ . These results suggest that BOCO@Ag can be a promising photo-activate antimicrobial candidate and provide security for humans health and the environment treatment.

Cu-Based Conductive MOF Grown in situ on Cu Foam as a Highly Selective and Stable Non-Enzymatic Glucose Sensor.

A non-enzymatic electrochemical sensor for glucose detection is executed by using a conductive metal-organic framework (MOF) Cu-MOF, which is built from the 2,3,6,7,10,11-hexahydroxytriphenylene (HHTP) ligand and copper acetate by hydrothermal reaction. The Cu-MOF demonstrates superior electrocatalytic activity for glucose oxidation under alkaline pH conditions. As an excellent non-enzymatic sensor, the Cu-MOF grown on Cu foam (Cu-MOF/CF) displays an ultra-low detection limit of 0.076 µM through a wide concentration range (0.001-0.95 mM) and a strong sensitivity of 30,030 mA µM-1 cm-2. Overall, the Cu-MOF/CF exhibits a low detection limit, high selectivity, excellent stability, fast response time, and good practical application feasibility for glucose detection and can promote the development of MOF materials in the field of electrochemical sensors.

π-Lewis-Base-Catalyzed Asymmetric Vinylogous Umpolung Reactions of Cyclopentadienones and Tropone.

We disclose that the carbonates of 4-hydroxy-2-cyclopentenones can form π-allylpalladium-based 1,2-carbodipoles, which isomerize to interesting η2 -Pd0 -cyclopentadienone complexes. Compared with the labile parent cyclopentadienone, the HOMO energy of the related η2 -complex was significantly raised via the back-bonding of Pd0 as a π-Lewis base, rendering the uncoordinated C=C bond an electron-richer dienophile in inverse-electron-demand aza-Diels-Alder-type reactions with diverse 1-azadienes. The vinylogous (aza)Morita-Baylis-Hillman or cross Rauhut-Currier addition to (imine)carbonyls or activated alkenes, respectively, was also realized to afford chiral [4+2] or [2+2] cycloadducts, respectively, after trapping the re-generated π-allylpalladium species. New C1 -symmetric ligands from simple chiral sources were developed, exhibiting high stereoselectivity even with racemic substrates via an unusual dynamic kinetic resolution process. Besides, tropone could be similarly activated by a Pd0 complex.

Ligand-Controlled Regiodivergent Asymmetric [5 + 2] and [3 + 2] Annulations of Vinyl Indoloxazolidones Catalyzed by Palladium.

Here, we present palladium-catalyzed regiodivergent asymmetric annulations of vinyl indoloxazolidones, which can act as 1,5-carbodipoles or 1,3-carbodipoles by tuning the chiral ligands and conditions, in the assemblies with sulfamate-derived cyclic imines and even activated alkenes. A diversity of polycyclic products are generally constructed with high regio- and enantioselectivity.

Hetero-Core-Shell BiNS-Fe@Fe as a Potential Theranostic Nanoplatform for Multimodal Imaging-Guided Simultaneous Photothermal-Photodynamic and Chemodynamic Treatment.

Photothermal/photodynamic therapy (PTT/PDT) and synergistic therapeutic strategies are often sought after, owing to their low side effects and minimal invasiveness compared to chemotherapy and surgical treatments. However, in spite of the development of the most PTT/PDT materials with good tumor-inhibitory effect, there are some disadvantages of photosensitizers and photothermal agents, such as low stability and low photonic efficiency, which greatly limit their further application. Therefore, in this study, a novel bismuth-based hetero-core-shell semiconductor nanomaterial BiNS-Fe@Fe with good photonic stability and synergistic theranostic functions was designed. On the one hand, BiNS-Fe@Fe with a high atomic number exhibits good X-ray absorption, enhanced magnetic resonance (MR) T2-weighted imaging, and strong photoacoustic imaging (PAI) signals. In addition, the hetero-core-shell provides a strong barrier to decline the recombination of electron-hole pairs, inducing the generation of a large amount of reactive oxygen species (ROS) when irradiated with visible-NIR light. Meanwhile, a Fenton reaction can further increase ROS generation in the tumor microenvironment. Furthermore, an outstanding chemodynamic therapeutic potential was determined for this material. In particular, a high photothermal conversion efficiency (η = 37.9%) is of significance and could be achieved by manipulating surface decoration with Fe, which results in tumor ablation. In summary, BiNS-Fe@Fe could achieve remarkable utilization of ROS, high photothermal conversion law, and good chemodynamic activity, which highlight the multimodal theranostic potential strategies of tumors, providing a potential viewpoint for theranostic applications of tumors.

"One stone, two birds": engineering 2-D ultrathin heterostructure nanosheet BiNS@NaLnF4 for dual-modal computed tomography/magnetic resonance imaging guided, photonic synergetic theranostics.

It is interesting yet challenging to design theranostic nanoplatforms for the accurate diagnosis and therapy of diseases; these nanoplatforms consist of single contrast-enhanced imaging or therapeutic agents, and they possess their own unique shortcomings that limit their widespread bio-medical applications. Therefore, designing a potential theranostic agent is an emerging approach for the synergistic diagnosis and therapeutics in bio-medical applications. Herein, a lanthanide-loaded (NaLnF4) heterostructure BiOCl ultrathin nanosheet (BiNS@NaLnF4) as a theranostic agent was synthesized facilely by a solvothermal protocol. BiNS@NaLnF4 was employed as a multi-modal contrast agent for computed tomography (CT) and magnetic resonance imaging (MRI), showing a high-performance X-ray absorption contrast effect, an outstanding T1-weighted imaging function result, good cytocompatibility and favorable in vivo effective imaging for CT. Notably, BiNS@NaLnF4 was applied to achieve a satisfactory photon-thermal conversion efficiency (35.3%). Moreover, the special heterostructure barrier achieved increased utilization of electrons/holes, enhancing the generation of reactive oxygen species (ROS) under visible-light irradiation to further expand the therapeutic effect. Dramatically, visible light emission with the up-conversion law was employed to stimulate ROS after irradiation with a 980 nm laser. Simultaneously, the as-prepared BiNS@NaLnF4 can be applied in photothermal/photodynamic therapy (PTT/PDT) investigation for tumor ablation. In summary, the results reveal that BiNS@NaLnF4 is a potential multi-modal theranostic candidate, providing new insights for synergistic theranostics of tumors.

Investigation of Microstructure and Nanoindentation Hardness of C+ & He+ Irradiated Nanocrystal SiC Coatings during Annealing and Corrosion.

The microstructure and nanoindentation hardness of unirradiated, irradiated, annealed and corroded SiC coatings were characterized. Irradiation of 400 keV C+ and 200 keV He+ with approximately 10 dpa did not cause obvious amorphous transformation to nanocrystal SiC coatings and induced helium bubbles with 2-3 nm dimension distributed uniformly in the SiC matrix. High temperature annealing resulted in the transformation of SiC nanocrystals into columnar crystals in the irradiated region. Line-shaped bubble bands formed at the columnar crystal boundaries and their stacking fault planes and made the formation of microcracks of hundreds of nanometers in length. Meanwhile, some isolated helium bubbles distributed in SiC grains still maintained a size of 2-3 nm, despite annealing at 1200 °C for 5 h. The SiC coating showed excellent corrosion resistance under high-temperature, high-pressure water. The weight of the sample decreased with the increase of corrosion time. The nanoindentation hardness and the elastic modulus increased significantly with C+ and He+ irradiation, while their values decreased with high-temperature annealing. An increase in the annealing temperature led to an increased reduction in the values. Corrosion caused the decrease of nanoindentation hardness and the elastic modulus in the whole test depth range, whether the samples were irradiated or unirradiated.

A Metal-Organic Framework Based on a Nickel Bis(dithiolene) Connector: Synthesis, Crystal Structure, and Application as an Electrochemical Glucose Sensor.

Functionalizing the redox-active tetrathiafulvalene (TTF) core with groups capable of coordination to metals provides new perspectives on the modulation of architectures and electronic properties of organic-inorganic hybrid materials. With a view to extending this concept, we have now synthesized nickel bis(dithiolene-dibenzoic acid), [Ni(C2S2(C6H4COOH)2)2], which can be considered as the inorganic analogue of the organic tetrathiafulvalene-tetrabenzoic acid (H4TTFTB). Likewise, [Ni(C2S2(C6H4COOH)2)2] is a redox-active linker for new functional metal-organic frameworks, as demonstrated here with the synthesis of [Mn2{Ni(C2S2(C6H4COO)2)2}(H2O)2]·2DMF, (1, DMF = N,N-dimethylformamide). 1 is isomorphic to the reported [Mn2(TTFTB)(H2O)2] (2) but is a better electrochemical glucose sensor due to the multiple oxidation-reduction states of the [NiS4] core, which allow glucose to be oxidized to glucolactone by the high oxidation state [NiS4] center. As a non-enzymatic glucose sensor, 1 on Cu foam (CF), 1-CF, was synthesized by a one-step hydrothermal method and exhibited an excellent electrochemical performance. The fabricated 1-CF electrode offers a high sensitivity of 27.9 A M-1 cm-2, with a wide linear detection range from 2.0 × 10-6 to 2.0 × 10-3 M, a low detection limit of 1.0 × 10-7 M (signal/noise = 3), and satisfactory stability and reproducibility.

Cu(I)-Catalyzed Asymmetric α-Allenylation of Activated Ketimines with 3-Butynoates.

An asymmetric α-regioselective allenylation reaction of activated ketimines with 3-butynoates is disclosed under Cu(I) catalysis, probably via the generation of nucleophilic γ-allenylcopper species in the presence of diisopropylethylamine. A broad range of imines, derived from diverse ketones such as isatins, pyrazolediones, isoquinoline-1,3,4-triones, and even trifluoromethyl alkynyl ketones, can be utilized, generally affording the corresponding α-allenyl amine derivatives in high yields (≤97%) with excellent enantioselectivities (≤99% ee).

The development of a hydrogen-helium dual-beam ion implanter.

Multiple ion beam facilities are powerful tools to simulate the irradiation effects of neutrons on relevant nuclear materials. Since hydrogen and helium are often generated in neutron irradiated materials as transmutation products and they play important roles in the defect evolution, the triple beam accelerator and transmission electron microscope link in situ facility instead of a monobeam or dual-beam facility is necessary to simulate neutron irradiation. A hydrogen-helium dual-beam ion implanter has been developed for a triple ion beam in situ facility at Xiamen University. A Penning ion source has been developed to produce H2 + and He+ simultaneously. A special system consisting of two Wien filters and an Einzel lens has been proposed to purify the species from a single Penning source and allow for the measurement of the He+/H2 + ratio, without disturbing the accelerator settings. The detail of this dual-beam ion implanter will be introduced in detail.

Asymmetric Allylic Alkylation with Deconjugated Carbonyl Compounds: Direct Vinylogous Umpolung Strategy.

An atom-economic and highly efficient vinylogous umpolung strategy is developed for deconjugated carbonyl compounds, which generate electron-deficient π-allylpalladium complexes with Pd(OAc)2 under ligand-free conditions. In cooperation with a chiral-phosphonium-based phase-transfer catalyst, the asymmetric direct oxidative allylic alkylations of 3-substituted oxindoles are furnished under O2 atmosphere. The γ- or even remote ϵ-regioselective alkylation products, with substantial substituents, are delivered with excellent enantioselectivity, and can be further used to access diverse chiral spirocyclic architectures effectively. The Mukaiyama dienol silyl ether can be utilized similarly, indicating that the current active π-allylpalladium species results from tautomerization of the PdII -dienolate intermediate.

Ion Irradiation-Induced Microstructural Evolution of Ni⁻Mo⁻Cr Low Alloy Steels.

As leading candidates of sheet steels for advanced nuclear reactors, three types of Ni⁻Mo⁻Cr high-strength low alloy (HSLA) steels named as CNST1, CNST2 and CNSS3 were irradiated by 400 keV Fe⁺ with peak fluence to 1.4 × 1014, 3.5 × 1014 and 7.0 × 1014 ions/cm², respectively. The distribution and morphology of the defects induced by the sample preparation method and Fe⁺ irradiation dose were investigated by transmission electron microscopy (TEM) and positron-annihilation spectroscopy (PAS). TEM samples were prepared with two methods, i.e., a focused ion beam (FIB) technique and the electroplating and twin-jet electropolishing (ETE) method. Point defects and dislocation loops were observed in CNST1, CNST2 and CNSS3 samples prepared via FIB. On the other hand, samples prepared via the ETE method revealed that a smaller number of defects was observed in CNST1, CNST2 and almost no defects were observed in CNST3. It is indicated that artifact defects could be introduced by FIB preparation. The PAS S-W plots showed that the existence of two types of defects after ion implantation included small-scale defects such as vacancies, vacancy clusters, dislocation loops and large-sized defects. The S parameter of irradiated steels showed a clear saturation in PAS response with increasing Fe⁺ dose. At the same irradiation dose, higher values of the S-parameter were achieved in CNST1 and CNST2 samples when compared to that in CNSS3 samples. The mechanism and evolution behavior of irradiation-induced defects were analyzed and discussed.

Investigation of Particles and Gas Bubbles in Zr⁻0.8Sn⁻1Nb⁻0.3Fe Zr Alloys Irradiated by Krypton Ions.

Two types of Zr⁻0.8Sn⁻1Nb⁻0.3Fe Zr alloys were irradiated by krypton ions in the temperature range from 320 to 400 °C. The microstructure of the as-received alloys showed that the sizes of Zr crystals and (Zr, Nb)2Fe particles with face-centered cubic (FCC) structure increased from 3.9 µm to 6.0 µm and from 74.6 nm to 89.6 nm, respectively, after cold rolling and subsequent annealing. Kr⁺ irradiation-induced bubble formation in the Zr matrix was observed. The size of the gas bubbles increased with increasing ion fluence and irradiation temperature. An equation that related the bubble size, ion fluence, and temperature were established. Irradiation-induced amorphization of particles was observed and found to be related to the fabrication process and irradiation parameters. The particles in alloy #1 showed a higher irradiation tolerance than those in alloy #2. The threshold damage dose for the amorphization of particles in alloy #2 was 3.5 dpa at 320 °C and 4.9 dpa at 360 °C. The mechanisms for bubble growth and particle amorphization are also discussed.