Crystal structures of two new high-pressure oxynitrides with composition SnGe4N4O4, from single-crystal electron diffraction.

SnGe4N4O4 was synthesized at high pressure (16 and 20 GPa) and high temperature (1200 and 1500°C) in a large-volume press. Powder X-ray diffraction experiments using synchrotron radiation indicate that the derived samples are mixtures of known and unknown phases. However, the powder X-ray diffraction patterns are not sufficient for structural characterization. Transmission electron microscopy studies reveal crystals of several hundreds of nanometres in size with different chemical composition. Among them, crystals of a previously unknown phase with stoichiometry SnGe4N4O4 were detected and investigated using automated diffraction tomography (ADT), a three-dimensional electron diffraction method. Via ADT, the crystal structure could be determined from single nanocrystals in space group P63mc, exhibiting a nolanite-type structure. This was confirmed by density functional theory calculations and atomic resolution scanning transmission electron microscopy images. In one of the syntheses runs a rhombohedral 6R polytype of SnGe4N4O4 could be found together with the nolanite-type SnGe4N4O4. The structure of this polymorph was solved as well using ADT.

Significant Improvement of Mechanical Properties of SiC-Nanowire-Reinforced SiCf/SiC Composites via Atomic Deposition of Ni Catalysts.

This study aimed to study the effects of different catalyst introduction methods on the distribution of SiC nanowires (SiCNWs) and the mechanical properties of SiCf/SiC composites. Two different catalyst-introduction methods (electroplating (EP) vs. atomic deposition (AD)) have been used to catalyze the growth of SiC nanowires in SiCf preforms. The morphology, structure and phase composition were systematically investigated using scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD). The SiCNWs-reinforced SiCf/SiC composited was densified by CVI. The compressive strength of the SiCNWs-reinforced SiCf/SiC composites was evaluated by radial crushing test. Compared with EP, atomic Ni catalysts fabricated by AD have higher diffusivity for better diffusion into the SiCf preform. The yield of SiCNWs is effectively increased in the internal pores of the SiCf preform, and a denser network forms. Therefore, the mechanical properties of SiCNW-containing SiCf/SiC composites are significantly improved. Compared with the EP-composites and SiCf/SiC composites, the compressive strength of AD-composites is increased by 51.1% and 56.0%, respectively. The results demonstrate that the use of AD method to grow SiCNWs is promising for enhancing the mechanical properties of SiCf/SiC composites.

The memory of neuronal mitochondrial stress is inherited transgenerationally via elevated mitochondrial DNA levels.

The memory of stresses experienced by parents can be passed on to descendants as a forecast of the challenges to come. Here, we discovered that the neuronal mitochondrial perturbation-induced systemic mitochondrial unfolded protein response (UPRmt) in Caenorhabditis elegans can be transmitted to offspring over multiple generations. The transgenerational activation of UPRmt is mediated by maternal inheritance of elevated levels of mitochondrial DNA (mtDNA), which causes the proteostasis stress within mitochondria. Furthermore, results from intercrossing studies using wild C. elegans strains further support that maternal inheritance of higher levels of mtDNA can induce the UPRmt in descendants. The mitokine Wnt signalling pathway is required for the transmission of elevated mtDNA levels across generations, thereby conferring lifespan extension and stress resistance to offspring. Collectively, our results reveal that the nervous system can transmit stress signals across generations by increasing mtDNA in the germline, enabling descendants to better cope with anticipated challenges.

Endoscopic endonasal open reduction for fractures of the frontal process of the maxilla.

OBJECTIVE: This study was performed to evaluate the clinical efficacy of endoscopic endonasal open reduction of fractures of the frontal process of the maxilla (FFPM). METHODS: We performed a retrospective study of patients who underwent endoscopic endonasal open reduction of FFPM from December 2013 to October 2018. The preoperative assessment included nasal endoscopy, computed tomography imaging, and three-dimensional craniofacial reconstruction. The clinical results were evaluated with a visual analog scale at 2 days and 1 year postoperatively. RESULTS: Thirty-two patients (25 male, 7 female) with an average age of 39 years were included in the study. All patients successfully underwent a surgical operation via the endoscopic endonasal approach with a nasal mucosal incision, and the nasal deformities were corrected. At the 1-year follow-up, six (18.8%) and 26 (81.2%) patients were somewhat satisfied and very satisfied with the aesthetic result, respectively, and five (15.6%) and 27 (84.4%) were somewhat satisfied and very satisfied with the functional result, respectively. CONCLUSION: Endoscopic endonasal open reduction can be considered a reliable method for anatomical reduction of FFPM. This technology provides a viable choice for the treatment of FFPM.

Dielectric Properties and Electromagnetic Wave Absorbing Performance of Single-Source-Precursor Synthesized Mo4.8Si3C0.6/SiC/Cfree Nanocomposites with an In Situ Formed Nowotny Phase.

For the first time, dielectric properties and electromagnetic wave (EMW) absorbing performance of single-source-precursor derived Mo4.8Si3C0.6/SiC/Cfree ceramic nanocomposites with a highly electrically conductive intermetallic Nowotny phase (NP, i.e., Mo4.8Si3C0.6) are reported. High-temperature phase evolution of the nanocomposites reveals that free carbon (Cfree) plays a crucial role in the in situ formation of the NP, indicating that the microstructure of the nanocomposites can be tailored via molecular design of the single-source precursors. Compared with SiC/Cfree and MoSi2/SiC/Cfree nanocomposites obtained under the same conditions, the Mo4.8Si3C0.6/SiC/Cfree nanocomposites exhibit significantly enhanced EMW absorbing performance. A minimum reflection loss (RL) of -59 dB was achieved at 8 GHz for the thickness of 2.46 mm, proving the superiority of the Mo4.8Si3C0.6/SiC/Cfree nanocomposite as an outstanding EMW absorbing material. On the basis of our previous discovery that the Mo4.8Si3C0.6 embedded in a SiC-based matrix with high specific surface area exhibits excellent electrocatalytic properties suitable for the electrochemical hydrogen evolution reaction, the present results prove that Mo4.8Si3C0.6/SiC/Cfree nanocomposites have to be considered as novel multifunctional materials with tailorable microstructure and excellent performance in two different fields including electrochemical water splitting and EMW absorption.

Videolaryngoscope-assisted coblation of epiglottic cysts.

PURPOSE: This study aims to investigate the safety and effectiveness of videolaryngoscope-assisted coblation of epiglottic cysts (VACECs) under general anesthesia. METHODS: Twenty-eight consecutive patients with epiglottic cysts (ECs), underwent VACECs in this prospective clinical series from January 2015 to March 2019. The pre-operative electronic flexible laryngoscopic or 70° rigid laryngeal endoscopic examination was carried out to assess the location and size of ECs. There was a periodical follow-up survey for all patients. RESULTS: A total 28 of patients were enrolled, including 12 men and 16 women, with an average age of 55 (range 24-78). The patient's medical history ranged from half a month to 2 years. The size of the cyst arranged from 0.8 to 1.5 cm. All patients were cured without pharyngeal or systemic complications. No tooth loss occurred in five patients (17.9%) with loose anterior teeth. Specimen pathology confirmed the diagnosis in all patients. No recurrence was found after more than half a year's follow-up. CONCLUSIONS: VACECs brings together the advantages of videolaryngoscope and coblation. It is a simple, safe and feasible procedure for patients with ECs and is worthy of clinical application.

Feasibility study on the application of coal gangue as landfill liner material.

Coal gangue is one of the largest industrial solid waste all over the world, and many methods have been proposed for the recycling of coal gangue. In the present study, the feasibility of using coal gangue as landfill liner material is studied through a series of laboratory tests in terms of hydraulic conductivity, sorption characteristics and leaching behavior. The results indicated that the hydraulic conductivity of coal gangue could be smaller than the regulatory requirement 1×10-7cm/s with a void ratio less than 0.60. The batch sorption experiments performed on Pb2+ and Zn2+ illustrated that the coal gangue showed remarkable sorption capacity for the two heavy metals, and the sorption capacity for Pb2+ was larger than that for Zn2+. Both the pseudo first-order and pseudo second-order models fitted well with the sorption kinetics data of the Pb2+ and Zn2+ on the coal gangue, and the Langmuir model was found to best-fit the sorption isotherms. The sorption capacity decreased in presence of multiple heavy metals, both for Pb2+ and Zn2+. Concentrations of heavy metals leached from the coal gangue were all below the regulatory limits from China MEP and U.S. EPA. These desirable characteristics indicated that the coal gangue has potential to be used as landfill liner materials.

Single-source-precursor synthesis of dense SiC/HfC(x)N(1-x)-based ultrahigh-temperature ceramic nanocomposites.

A novel single-source precursor was synthesized by the reaction of an allyl hydrido polycarbosilane (SMP10) and tetrakis(dimethylamido)hafnium(iv) (TDMAH) for the purpose of preparing dense monolithic SiC/HfC(x)N(1-x)-based ultrahigh temperature ceramic nanocomposites. The materials obtained at different stages of the synthesis process were characterized via Fourier transform infrared (FT-IR) as well as nuclear magnetic resonance (NMR) spectroscopy. The polymer-to-ceramic transformation was investigated by means of MAS NMR and FT-IR spectroscopy as well as thermogravimetric analysis (TGA) coupled with in situ mass spectrometry. Moreover, the microstructural evolution of the synthesized SiHfCN-based ceramics annealed at different temperatures ranging from 1300 °C to 1800 °C was characterized by elemental analysis, X-ray diffraction, Raman spectroscopy and transmission electron microscopy (TEM). Based on its high temperature behavior, the amorphous SiHfCN-based ceramic powder was used to prepare monolithic SiC/HfC(x)N(1-x)-based nanocomposites using the spark plasma sintering (SPS) technique. The results showed that dense monolithic SiC/HfC(x)N(1-x)-based nanocomposites with low open porosity (0.74 vol%) can be prepared successfully from single-source precursors. The average grain size of both HfC0.83N0.17 and SiC phases was found to be less than 100 nm after SPS processing owing to a unique microstructure: HfC0.83N0.17 grains were embedded homogeneously in a ß-SiC matrix and encapsulated by in situ formed carbon layers which acted as a diffusion barrier to suppress grain growth. The segregated Hf-carbonitride grains significantly influenced the electrical conductivity of the SPS processed monolithic samples. While Hf-free polymer-derived SiC showed an electrical conductivity of ca. 1.8 S cm(-1), the electrical conductivity of the Hf-containing material was analyzed to be ca. 136.2 S cm(-1).

[Nasopharyngeal teratomas (a case report and review of the literature)].

OBJECTIVE: To investigate the clinical characteristics of nasopharyngeal teratomas (NPT), improve the diagnosis and treatment of the disease. METHOD: We reported a 14 years old girl with NPT, and reviewed the literatures. RESULT: NPT was transorally expected under nasal endoscope, no recurrence was found over a 5 year follow-up. CONCLUSION: NPT is rare,the diagnosis of the disease relies on clinical manifestations, imaging and pathological examination. Transoral endoscopic surgery is an effective method of treatment.

Iron, lanthanum and manganese oxides loaded on gamma-AI2O3 for selective catalytic reduction of NO with NH3 at low temperature.

A series of Mn/Al2O3, La-Mn/Al2O3 and Fe-La-Mn/Al2O3 catalysts were prepared by an impregnation method and investigated for selective catalytic reduction of NO with NH3 at low temperature. The experimental results revealed that NO conversion over La-Mn/Al2O3 was obviously improved after La doping. Addition of Fe increased both NO conversion and the resistance to H2O and SO2. The catalyst Fe0.04La0.03Mn0.06/Al2O3 with a load mass of MnO2 = 6%, La2O3 = 3% and Fe2O3 = 4% exhibited relatively high catalytic activity and yielded 98% NO conversion at 260 degrees with a space velocity of 15,000 h(-1). Meanwhile, the catalytic activity was slightly decreased in the presence of H2O and SO2. Moreover, the catalysts were characterized by N2 adsorption measurement, X-ray diffraction and X-ray photoelectron spectroscopy. The results showed that the doping of La enhanced the dispersion and oxidation states of Mn on the surface of Al2O3. On the surface of the Fe0.04La0.03Mn0.06/Al2O3 catalyst, La was highly dispersed and a mixed oxidation state of Mn existed, while iron ions were only in the Fe3+ state. The mechanism of selective catalytic reduction over these catalysts is also discussed. In this experiment, metal oxides loaded on the support were catalytic centres which served as electron transfer during NO reduction. The electron transfer between Mn3+ and Fe3+ might also exist and the mixture oxidation states of Mn on the surface of the Fe0.04La0.03Mn0.06/Al2O3 catalyst contributed to the SCR activity.

Adsorption mechanism of sodium dodecyl benzene sulfonate on carbon blacks by adsorption isotherm and zeta potential determinations.

Surfactant solutions were propounded to remove fine and hydrophobic carbon black particles from coal-fired flue gas. The adsorption mechanisms between sodium dodecyl benzene sulfonate (SDBS, an anionic surfactant) and carbon black particles in suspension were investigated. The influence of inorganic salt (NaCl) was also considered. As results showed, hydrophobic interactions contributed to the strong adsorption between SDBS and carbon black particles in the absence of NaCl, and adding NaCl affected the adsorption process. The adsorption amount of SDBS significantly increased when NaCl was added into the SDBS solution; however, when SDBS was in low concentration, the amount of adsorbed SDBS, which was responsible for the shift of zeta potentials, varied little under different concentrations of NaCl. This indicated that the adsorption of SDBS was mainly caused by hydrophobic interaction and Na+ could not change the adsorption of SDBS on adsorption site when SDBS was in low concentration. Moreover, the adsorbed SDBS and Na+ were retained in the Stern layer.

[In vitro comparison of transdermal characteristics of xiaoyu ointment and xiaoyu plaster].

OBJECTIVE: Through the comparison of Xiaoyu ointment and xiaoyu plaster by in vitro transdermal demonstrate, to demonstrate the scientificity and feasibility of reformed formulation. METHOD: The improved Franz diffusion cells and in vitro rabbit skin were used in vitro penetration experiment with emodin as an indicator of penetration rate quantitated by HPLC. RESULT: The cumulative penetration rate of emodin in Xiaoyu ointment fit the model of Weibull distribution, while the cumulative penetration rate of emodin in Xiaoyu plaster fit the model of Density equation. Take emodin as an index,the transdermal rate in Xiaoyu plaster was 1.93 times as Xiaoyu ointment, and the total penetrated amount was 2.84 times as Xiaoyu ointment. The results showed that the emodin of xiaoyu plaster reserved in the skin were 3.95 times more than the ointment. CONCLUSION: The penetration rate, total penetrated amount and the reserves in the skin of Xiaoyu plaster were better than the ointment, and the transdermal dosage form was better than the original form.

Effects of cake collapse caused by deposition of fractal aggregates on pressure drop during ceramic filtration.

A cake collapse model was developed by taking the combined effects of fractal dimension, relaxation ratio, coordination number, and aggregate diameter into consideration. The cake porosity including intraaggregate and interaggregate porosities was modeled successively by three typical coordination numbers (n = 6, 8, and 12). Accordingly, an inversion method made it possible to deduce the coordination number using the measured cake porosities, and the reverse-calculated value with minimum error and the corresponding relaxation ratios were applied as the parameters for the model. As a result, the profiles of intraaggregate and interaggregate porosities and cake porosity were respectively predicted in contrast to the integrated variation of the relaxation ratio and the fractal dimension. Furthermore, a comparison between the model predictions of the cake pressure drop gradients with and without aggregate compression was conducted to validate the presence of cake collapse. The results show that the predictions based on the proposed collapse model are in agreement with the experiments, and the coordination number is one of the key factors that must be incorporated into the cake collapse models.

Study on activated carbon derived from sewage sludge for adsorption of gaseous formaldehyde.

The aim of this work is to evaluate the adsorption performances of activated carbon derived from sewage sludge (ACSS) for gaseous formaldehyde removal compared with three commercial activated carbons (CACs) using self-designing adsorption and distillation system. Formaldehyde desorption of the activated carbons for regeneration was also studied using thermogravimetric (TG) analysis. The porous structure and surface characteristics were studied using N2 adsorption and desorption isotherms, scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR). The results show that ACSS has excellent adsorption performance, which is overall superior to the CACs. Adsorption theory indicates that the ACSS outperforms the CACs due to its appropriate porous structure and surface chemistry characteristics for formaldehyde adsorption. The TG analysis of desorption shows that the optimum temperature to regenerate ACSS is 75°C, which is affordable and economical for recycling.

[Research on SCR denitrification of MnOx/Al2O3 modified by CeO2 and its mechanism at low temperature].

The Al2O3,which has large specific surface area and is used as carrier,was prepared by sol-gel method in this study. Series catalysts of MnOx, CeO2 plus MnOx supported on Al2O3 by isometric impregnation method. The SCR denitrification experimental conditions were as follows: NH3 as reductive agent, certain gas velocity and suitable ratio of gas mixed was setup. Furthermore, the experiments of BET, XRD and SEM were also carried out respectively in order to obtain physicochemical properties of the prepared catalysts. The experimental results showed that the loading of active component and calcination temperature made a big difference to the catalysts' performance. With appropriate addition of CeO2, MnOx/Al2O3 exhibits better activity and stability. For MnOx/Al2O3, the catalytic activity on NO was greatly influenced by its loaded content, and 7% MnOx/Al2O3 showed superior catalytic activity among the MnOx/Al2O3. The addition of CeO2 could greatly improve the dispersibility of MnOx on the carrier and increase its catalytic activity. The 4% CeO2 addition was the optimum loaded mass precent. Forthermore, 550 degrees C is the best calcination temperature, as MnOx formed different crystalline phases with temperature, at the same time, the addition of CeO2 could affect MnOx crystalline phase. The catalytic mechanism of SCR on NO was also discussed.