Self-Catalyzed Hydrogenated Carbon Nano-Onions Facilitates Mild Synthesis of Transparent Nano-Polycrystalline Diamond.

Transparent nano-polycrystalline diamond (t-NPD) possesses superior mechanical properties compared to single and traditional polycrystalline diamonds. However, the harsh synthetic conditions significantly limit its synthesis and applications. In this study, a synthesis routine is presented for t-NPD under low pressure and low temperature conditions, 10 GPa, 1600 °C and 15 GPa, 1350 °C similar with the synthesis condition of organic precursor. Self-catalyzed hydrogenated carbon nano-onions (HCNOs) from the combustion of naphthalene enable synthesis under nearly industrial conditions, which are like organic precursor and much lower than that of graphite and other carbon allotropes. This is made possible thanks to the significant impact of hydrogen on the thermodynamics, as it chemically facilitates phase transition. Ubiquitous nanotwinned structures are observed throughout t-NPD due to the high concentration of puckered layers and stacking faults of HCNOs, which impart a Vickers hardness about 140 GPa. This high hardness and optical transparency can be attributed to the nanocrystalline grain size, thin intergranular films, absence of secondary phase and pore-free features. The facile and industrial-scale synthesis of the HCNOs precursor, and mild synthesis conditions make t-NPD suitable for a wide range of potential applications.

Modulating Charge-Density Wave Order and Superconductivity from Two Alternative Stacked Monolayers in a Bulk 4Hb-TaSe2 Heterostructure via Pressure.

Two-dimensional (2D) van der Waals heterostructures (VDWHs) containing a charge-density wave (CDW) and superconductivity (SC) have revealed rich tunability in their properties, which provide a new route for optimizing their novel exotic states. The interaction between SC and CDW is critical to its properties; however, understanding this interaction within VDWHs is very limited. A comprehensive in situ study and theoretical calculation on bulk 4Hb-TaSe2 VDWHs consisting of alternately stacking 1T-TaSe2 and 1H-TaSe2 monolayers are investigated under high pressure. Surprisingly, the superconductivity competes with the intralayer and adjacent-layer CDW order in 4Hb-TaSe2, which results in substantially and continually boosted superconductivity under compression. Upon total suppression of the CDW, the superconductivity in the individual layers responds differently to the charge transfer. Our results provide an excellent method to efficiently tune the interplay between SC and CDW in VDWHs and a new avenue for designing materials with tailored properties.

Synthesis, Characterization, and First-Principles Analysis of the MAB-Like Ternary Transition-Metal Boride Fe(MoB)2.

Novel transition-metal borides have attracted considerable attention because they exhibit high stability under extreme conditions. Compared with binary borides, ternary transition-metal borides (TTMBs) exhibit novel boron substructures and diverse properties, which result in excellent designability. In this study, we synthesized the MAB-like (where M = iron, A = molybdenum, and B = boron) phase Fe(MoB)2 using a high-pressure and high-temperature method. Fe(MoB)2 exhibited ferromagnetic metastable characteristics with a saturation magnetization of 8.35 emu/g at room temperature. Microhardness measurement revealed an indentation hardness of 10.72 GPa, which was higher than those of conventional magnetic materials. First-principles calculations revealed excellent mechanical properties, which mainly originated from the strong covalent short B2 chains. Furthermore, magnetism was attributed to the Fe 3d electrons. Numerous d-d hybridizations existed between the Fe 3d eg and Mo 4d orbitals, and the antibonding/nonbonding state difference for up/down-spin electrons in the hybridization orbitals led to the local magnetic moment of Fe(MoB)2. The magnetic anisotropy energy analyses reveal that Fe(MoB)2 prefers the easy magnetization axis along the z direction, and Mo atom acts as a medium to realize the exchange action between two Fe atoms. The B-B and Fe-B bonds were considerably stronger than the Fe-Mo and Mo-B bonds, and Fe(MoB)2 exhibited a class of atomically laminate composed of FeB2 and Mo layers. These results may provide guidance for the design of novel multifunctional TTMBs by adjusting the interactions between binary metal components.

Correction: Synthesis and characterization of a strong ferromagnetic and high hardness intermetallic compound Fe2B.

Correction for 'Synthesis and characterization of a strong ferromagnetic and high hardness intermetallic compound Fe2B' by Xingbin Zhao et al., Phys. Chem. Chem. Phys., 2020, 22, 27425-27432, DOI: 10.1039/D0CP03380D.

Three-dimensional construction of micrometer level in rat stomach by synchrotron radiation.

BACKGROUND: The structural changes of gastric mucosa are considered as an important window of early gastric lesions. This article shows an imaging method of the stomach that does not use imaging agents. X-ray phase-contrast images of different stages of gastric development were taken using micrometer level X-ray in-line phase-contrast imaging (XILPCI) technique on synchrotron radiation facility. The aim of the study was to demonstrate that the imaging technique is an appropriate method for micron imaging of the gastric structures. METHODS: The stomachs of 4-, 6- and 12-week-old rats were removed and cleaned. XILPCI has 1000 times greater soft tissue contrast than that of X-ray traditional absorption radiography. The projection images of the rats stomachs were recorded by an XILPCI charge coupled device (CCD) at 9-µm image resolution. RESULTS: The X-ray in-line phase-contrast images of the different stages of rats' gastric specimens clearly showed the gastric architectures and the details of the gastro-duodenal region. 3-dimensional (3D) stomach anatomical structure images were reconstruction. CONCLUSION: The reconstructed gastric 3D images can clearly display the internal structure of the stomach. XILPCI may be a useful method for medical research in the future.

Compression-Driven Internanocluster Reaction for Synthesis of Unconventional Gold Nanoclusters.

Can the active kernels in ultrasmall metal nanoparticles (nanoclusters, NCs) react with one another, or can the internanocluster reaction occur when they are in close enough proximity? To resolve this fundamental issue, we investigated the solid-state internanocluster reaction of the most studied gold NC Au25 (SR)18 (SR: thiolate). A novel NC was produced by increasing the pressure to 5 GPa, whose composition was determined to be Au32 (SC2 H4 Ph)24 by mass spectrometry and thermogravimetric analysis. As revealed by single-crystal X-ray crystallography, the structure, a bicuboid Au14 kernel and three pairs of interlocked trimetric staples, has not been reported and endows the NC with obvious photoluminescence. DFT calculations indicate that the staples contribute substantially to the absorption properties. Further experiments reveal the pressure (internanocluster distance) can tune the internanocluster reaction, and the resulting product is not necessarily the thermodynamic product.

Synthesis and characterization of a strong ferromagnetic and high hardness intermetallic compound Fe2B.

Magnetic materials attract great attention due to their fundamental importance and practical application. However, the relatively inferior mechanical properties of traditional magnetic materials limit their application in a harsh environment. In this work, we report an outstanding magnetic material that exhibits both fantastic mechanical and excellent magnetic properties, CuAl2-type Fe2B, synthesized by the high pressure and high temperature method. The magnetic saturation of Fe2B is 156.9 emu g-1 at room temperature and its Vickers hardness is 12.4 GPa which outclasses those of traditional magnetic materials. It exhibits good conductivity with a resistivity of 5.6 × 10-7 Ω m. Fe2B is a promising strong ferromagnetic material with high hardness, which makes it a good candidate for multifunction applications in a harsh environment. The high hardness of Fe2B originates from the Fe-B bond framework, and the strong ferromagnetism is mainly attributed to the large number of unpaired Fe 3d electrons. The competition of Fe 3d electrons to fall into Fe-B bonds or Fe-Fe bonds is the main factor for its magnetism and hardness. This work bridges the chasm between strong ferromagnetism and high hardness communities.

Long non-coding RNA TGLC15 advances hepatocellular carcinoma by stabilizing Sox4.

BACKGROUND: The hepatocellular carcinoma (HCC) belongs to a common malignancy especially in China. Recent data have clarified important roles of long non-coding RNAs (lncRNAs) in HCC. However, the role of a novel intergenic lncRNA termed TGLC15 is still elusive. METHODS: We screened for novel lncRNAs using lncRNA profiling. TGLC15 expression was quantified by qRT-PCR. In vitro experiments such as migration and viability assays were performed. In vivo implantation experiments were conducted to investigate tumorigenic functions of TGLC15. Combined RNA immunoprecipitation (RIP) and mass spectrometry (MS) were utilized to uncover Sox4 as TGLC15 binding protein. RESULTS: TGLC15 is significantly overexpressed in tumor tissues and HCC cell lines. Higher TGLC15 levels correlated with advanced malignant characteristics such as TNM stages, tumor size, and metastasis. TGLC15 advanced HCC migration and viability. The in vivo experiments supported that xenograft tumor growth and proliferation were facilitated by TGLC15 overexpression. Mechanistic studies showed that TGLC15 interacted with Sox4 and interaction between TGLC15 and Sox4 could stabilize Sox4 via reduction in proteasome-mediated degradation. CONCLUSIONS: Collectively, our data have identified a novel lncRNA TGLC15 during HCC development. The TGLC15-Sox4 signaling might be a potential target for pharmaceutical intervention.

Revealing the Unusual Rigid Boron Chain Substructure in Hard and Superconductive Tantalum Monoboride.

Poor electrical conductivity severely limits the diverse applications of high hardness materials in situations where electrical conductivities are highly desired. A "covalent metal" TaB with metallic electrical conductivity and high hardness has been fabricated by a high pressure and high temperature method. The bulk modulus, 302.0(4.9) GPa, and Vickers hardness, 21.3 GPa, approaches and even exceeds that of traditional insulating hard materials. Meanwhile, temperature-dependent electrical resistivity measurements show that TaB possesses metallic conductivity that rivals some widely-used conductors, and it will transform into a superconductor at Tc =7.8 K. Contrary to common understanding, the hardness of TaB is higher than that of TaB2 , which indicates that low boron concentration borides could be mechanically better than the higher boron concentration counterparts. Compression behavior and first principles calculations denote that the high hardness is associated with the ultra-rigid covalent boron chain substructure. The hardness of TaB with different topologies of boron substructure shows that besides incorporating higher boron content, manipulating light element backbone configurations is also critical for higher hardness amongst transition metal borides with identical boron content.

Role of TM-TM Connection Induced by Opposite d-Electron States on the Hardness of Transition-Metal (TM = Cr, W) Mononitrides.

Recent reports exposed an astonishing factor of high hardness that the connection between transition-metal (TM) atoms could enhance hardness, which is in contrast to the usual understanding that TM-TM will weaken hardness as the source of metallicity. It is surprising that there are two opposite mechanical characteristics in the one TM-TM bond. To uncover the intrinsic reason, we studied two appropriate mononitrides, CrN and WN, with the same light-element (LE) content and valence electron concentration. The two high-quality compounds were synthesized by a new metathesis under high pressure, and the Vickers hardness is 13.0 GPa for CrN and 20.0 GPa for WN. Combined with theoretical calculations, we found that the strong correlation of d electrons in TM-TM could seriously affect hardness. Thus, we make the complementary suggestions of the previous hardness factors that the antibonding d-electron state in TM-TM near the Fermi level should be avoided and a strong d covalent coupling in TM-TM is very beneficial for high hardness. Our results are very important for the further design of high-hardness and multifunctional TM and LE compounds.

Double-zigzag boron chain-enhanced Vickers hardness and manganese bilayers-induced high d-electron mobility in Mn3B4.

The D7b-type structure Mn3B4 was fabricated by high-temperature and high-pressure (HPHT) methods. Hardness examination yielded an asymptotic Vickers hardness of 16.3 GPa, which is much higher than that of Mn2B and MnB2. First principle calculations and XPS results demonstrated that double zigzag boron chains form a strong covalent skeletons, which enhances this structure's integrity with high hardness. Considering that the hardensses of MnB and Mn3B4 are higher than those of Mn2B and MnB2, zigzag and double zigzag boron backbones are superior to isolated boron and graphite-like boron layer backbones for achieving higher hardness. This situation also states that a higher boron content is not the sole factor for the higher hardness in the low boron content transition metal borides. Futhermore, the co-presence of metallic manganese bilayers contribute to the high d-electron mobility and generate electrical conductivity and antiferromagnetism in Mn3B4 which provide us with a new structure prototype to design general-purpose high hardness materials.

Structure stabilization effect of configuration entropy in cubic WN.

The microscopic structure of cubic WN has been studied combining scanning transmission electron microscopy and first-principles calculations. Because of the contribution of configurational entropy, NaCl-type WN with disordered vacancies becomes more stable at high temperatures than NbO-type WN. Moreover, electron beam irradiation can induce an order-disorder transition in cubic WN. It is suggested that the ordered NbO-type WN can be obtained after annealing below the transition temperature. The results shed light on the stability of materials synthesized at high pressures and high temperatures.

A faster and simpler way of operation for Meckel's diverticulum: basal ligation combined with intraoperative frozen section.

BACKGROUND: The key step in Meckel's diverticulectomy (MD) is to achieve complete resection of MD along with the ectopic epithelium. Currently main treatment methods for Meckel's diverticulum are either intestinal resection and anastomosis or wedge resection. Here we introduced a new method to treat MD. The goal of this study was to investigate the clinical effects and advantages of a new operation method for Meckel's diverticulum: basal ligation combined with intraoperative frozen section. METHODS: 262 cases of Meckel's diverticulum were resected with simple basal ligation operation. Intraoperative frozen pathological section was performed to determine surgery strategies. Based on the existence of basal residual ectopic mucosa, surgery was either terminated or further wedge intestinal resection or bowel resection was performed. RESULTS: All 262 surgeries were successfully completed. Additional wedge resection or bowel resection was performed in only 23 of them due to the presence of ectopic basal residual gastric mucosa. No ectopic mucosa was found for the other cases, and the operation ended after basal ligation. All patients had no complications such as intestinal fistula, bleeding for 6 months-7.6 years after surgery. CONCLUSIONS: Intraoperative frozen pathological examination can well determine whether ectopic Meckel's diverticulum mucosa locates at the basal part. Basal ligation is a safe and effective operation method, and it can significantly shorten the operation time and postoperative fasting time.

Antidepressant Imipramine Protects Bupivacaine-Induced Neurotoxicity in Dorsal Root Ganglion Neurons Through Coactivation of TrkA and TrkB.

In our work, we used an in vitro culture model to investigate whether antidepressant imipramine (Ip) may protect bupivacaine (Bv)-induced neurotoxicity in mouse dorsal root ganglion (DRG). Adult mouse DRG was treated with 5 mM Bv in vitro to induce neurotoxicity. DRG was then pre-treated with Ip, prior to Bv, to examine its effects on protecting Bv-induced DRG apoptosis and neurite degeneration. Ip-induced dynamic changes in Trk receptors, including TrkA/B/C and phosphor (p-)TrkA/B/C, were examined by qPCR and Western blot. TrkA and TrkB were inhibited by siRNAs to further investigate their functional role in Ip- and Bv-treated DRG. Ip protected Bv-induced apoptosis and neurite loss in DRG. Ip did not alter TrkA/B/C expressions, whereas significantly augmented protein productions of p-TrkA and p-TrkB, but not p-TrkC. SiRNA-mediated TrkA or TrkB downregulation inhibited Trk receptors, and reduced p-TrkA and p-TrkB in DRG. TrkA or TrkB downregulation alone had no effect on Ip-induced protection in Bv-injured DRG. However, co-inhibition of TrkA and TrkB significantly ameliorated the protective effect of Ip on Bv-induced apoptosis and neurite loss in DRG. Imipramine protected bupivacaine-induced neurotoxicity in DRG, likely via the co-activation of TrkA and TrkB signaling pathways. J. Cell. Biochem. 118: 3960-3967, 2017. © 2017 Wiley Periodicals, Inc.

Highly Active, Nonprecious Electrocatalyst Comprising Borophene Subunits for the Hydrogen Evolution Reaction.

Developing nonprecious hydrogen evolution electrocatalysts that can work well at large current densities (e.g., at 1000 mA/cm2: a value that is relevant for practical, large-scale applications) is of great importance for realizing a viable water-splitting technology. Herein we present a combined theoretical and experimental study that leads to the identification of α-phase molybdenum diboride (α-MoB2) comprising borophene subunits as a noble metal-free, superefficient electrocatalyst for the hydrogen evolution reaction (HER). Our theoretical finding indicates, unlike the surfaces of Pt- and MoS2-based catalysts, those of α-MoB2 can maintain high catalytic activity for HER even at very high hydrogen coverage and attain a high density of efficient catalytic active sites. Experiments confirm α-MoB2 can deliver large current densities in the order of 1000 mA/cm2, and also has excellent catalytic stability during HER. The theoretical and experimental results show α-MoB2's catalytic activity, especially at large current densities, is due to its high conductivity, large density of efficient catalytic active sites and good mass transport property.

Synthesis and Mechanical Character of Hexagonal Phase δ-WN.

In this work, high-quality bulk WC-structured WN (δ-WN) was synthesized via an untraditional method and the structure was accurately determined by X-ray diffraction and Rietveld refinement. In the process of synthesizing δ-WN, W2N3 and melamine were used as tungsten source and nitrogen source, respectively. The result of successfully synthesized high-quality δ-WN indicates that our method is an effective route for synthesizing high-quality bulk δ-WN and melamine is a pure nitrogen source for introducing the nitrogen to the metal precursor. The mechanical properties, bulk modulus, and Vickers hardness (HV) were first investigated by in situ high-pressure X-ray diffraction and Vickers microhardness tests, respectively. It is worth noting that the bulk modulus of δ-WN is 373 ± 8.3 GPa, which is comparable to that of c-BN. The Vickers hardness is 13.8 GPa under an applied load of 4.9 N. It is worth noting that W-W metallic bond and W-N ionic bond are mainly chemical bond in δ-WN based on the analysis of electron localization function (ELF), density of states (DOS), and Mulliken population. This result can well clarify that δ-WN is only a hard material for the lack of strong W-N covalent bonds to form 3D network structure. Our results are helpful to understand the hardness mechanism and design superhard materials in transition-metal nitrides.

WB2: not a superhard material for strong polarization character of interlayer W-B bonding.

In this work, the structure of WB2 synthesized at high pressure and high temperature (HPHT) was accurately determined by X-ray diffraction and Rietveld refinement. Its asymptotic Vickers hardness (Hv) value is 25.5 GPa which is much lower than the previous theoretical results (36-40 GPa). It is worth noting that the chemical bonds between the W layers and two different kinds of B layers show obvious polarization character based on the results obtained from X-ray photoelectron spectroscopy (XPS) and electron localization functions (ELFs), density of states (DOS), topological analysis of the static electron density and Mulliken population. This result can well clarify that WB2 is only a hard but not superhard material. Thus, a 3D network structure can not be formed between the W layers and the B layers which is previously predicted by theoretical calculations. Our results are helpful to understand the hardness mechanism and design superhard materials in TMBs.

Resection vs. ablation for alpha-fetoprotein positive hepatocellular carcinoma within the Milan criteria: a propensity score analysis.

BACKGROUND & AIMS: The lack of histopathological confirmation of hepatocellular carcinoma (HCC) diagnosis for patients receiving ablation may result in misdiagnosis of benign liver nodule as HCC occasionally, contributing to false treatment efficacy. This underestimated issue is one reason why the ablation efficacy remains undetermined compared with hepatic resection. Our aim is to compare the efficacy of ablation and resection for HCC within the Milan criteria after excluding the impact of misdiagnosis. METHODS: Alpha-fetoprotein > 200 ng/ml was introduced as an inclusion criterion to improve diagnosis accuracy. A total of 435 (resection, 310; ablation, 125) HCC patients within the Milan criteria and without portal hypertension were enrolled. Propensity score matching analysis identified 259 (resection, 150; ablation, 109) patients to compare treatment efficacy. RESULTS: Before matching, the survival of resection group were superior to ablation group with 5-year overall survival (OS) rate of 77.6% vs. 53.8% (P < 0.001), respectively, and 5-year recurrence-free survival (RFS) rate of 57.2% vs. 29.1% (P < 0.001) respectively. After matching, the baseline was well-balanced between the two groups. The 5-year OS rates were 71.5% vs. 51.3% (P < 0.001), and 5-year RFS rates were 56.1% vs. 25.6% (P < 0.001) for the resection and ablation groups respectively. Cox regression analysis identified ablation as an independent predictor for mortality and tumour recurrence (HR: 2.123 and 2.308, respectively; both P < 0.01). CONCLUSIONS: Hepatic resection provides better OS and RFS than ablation for alpha-fetoprotein positive HCC patients within the Milan criteria and without portal hypertension.

Investigating Robust Honeycomb Borophenes Sandwiching Manganese Layers in Manganese Diboride.

We report a robust honeycomb boron layers sandwiching manganese layers compound, MnB2, synthesized by high pressure and high temperature. First-principle calculation combined with X-ray photoelectron spectrum unravel that the honeycomb boron structure was stabilized by filling the empty π-band via grabbing electrons from manganese layers. Honeycomb boron layers sandwiching manganese layers is an extraordinary prototype of this type of sandwiched structure exhibiting electronic conductivity and ferromagnetism. Hydrostatic compression of the crystal structure, thermal expansion, and the hardness testing reveal that the crystal structure is of strong anisotropy. The strong anisotropy and first-principle calculation suggests that B-B bonds in the honeycomb boron structure are a strong directional covalent feature, while the Mn-B bonds are soft ionic nature. Sandwiching honeycomb boron layers with manganese layers that combine p-block elements with magnetic transition metal elements could endow its novel physical and chemical properties.

Rational design of D-A1-D-A2 conjugated polymers with superior spectral coverage.

The spectral coverage of a light-harvesting polymer largely determines the maximum achievable photocurrent in organic photovoltaics, and therefore constitutes a crucial parameter for improving their performance. The D-A1-D-A2 copolymer motif is a new and promising design strategy for extending the absorption range by incorporating two acceptor units with complementary photoresponses. The fundamental factors that promote an extended absorption are here determined for three prototype D-A1-D-A2 systems through a combination of experimental and computational methods. Systematic quantum chemical calculations are then used to reveal the intrinsic optical properties of ten further D-A1-D-A2 polymer candidates. These investigated polymers are all predicted to exhibit intense primary absorption peaks at 615-954 nm, corresponding to charge-transfer (CT) transitions to the stronger acceptor, as well as secondary absorption features at 444-647 nm that originate from CT transitions to the weaker acceptors. Realization of D-A1-D-A2 polymers with superior spectral coverage is thereby found to depend critically on the spatial and energetic separation between the two distinct acceptor LUMOs. Two promising D-A1-D-A2 copolymer candidates were finally selected for further theoretical and experimental study, and demonstrate superior light-harvesting properties in terms of significantly extended spectral coverage. This demonstrates great potential for enhanced light-harvesting in D-A1-D-A2 polymers via multiple absorption features compared to traditional D-A polymers.