Search

Changquan Fang,1,* Limin Xu,2,* Jiarong Tan,1 Hongyi Tan,1 Junhong Lin,1 Ziwen Zhao3 1Department of Pulmonary and Critical Care Medicine, Huizhou Central People’s Hospital, Huizhou, Guangdong Province, Peoples’ Republic of China; 2Department of Geriatrics, Huizhou First People’s Hospital, Huizhou, Guangdong Province, Peoples’ Republic of China; 3Department of Pulmonary and Critical Care Medicine, Guangzhou First People’s Hospital Affiliated to South China University of Technology, Guangzhou, Guangdong Province, Peoples’ Republic of China*These authors contributed equally to this workCorrespondence: Junhong Lin, Department of Pulmonary and Critical Care Medicine, Huizhou Central People’s Hospital, No. 41 Eling North Road, Huicheng District, Huizhou City, Guangdong Province, 516000, Peoples’ Republic of China, Tel +86 130-7528-2839, Email hz_ljh@163.com Ziwen Zhao, Department of Pulmonary and Critical Care Medicine, Guangzhou First People’s Hospital Affiliated to South China University of Technology, No. 1 Panfu Road, Yuexiu District, Guangzhou City, Guangdong Province, 510180, Peoples’ Republic of China, Tel +86 130-0687-2260, Email zhaozw@yeah.netAbstract: Psittacosis is a rare zoonotic disease caused by Chlamydia psittaci infection, and tetracyclines are the preferred treatment. Omadacycline is a novel tetracycline that has a strong in vitro antibacterial activity against atypical pathogens, including C. psittaci; however, clinical data for its usage are lacking. We report a patient with severe C. psittaci-induced pneumonia presenting with a high fever, muscle aches, severe hepatic and renal insufficiency, and acute respiratory failure requiring tracheal intubation and mechanical ventilation. The condition was diagnosed using metagenomic next-generation sequencing. The patient was discharged after treatment with omadacycline. The findings of this study suggest that metagenomic next-generation sequencing is valuable for the rapid and accurate diagnosis of psittacosis. With its good safety profile and no requirement for dose adjustment in special populations, omadacycline is a new option for the treatment of severe C. psittaci pneumonia. However, additional case reports are needed to support this conclusion.Keywords: Chlamydia psittaci, pneumonia, omadacycline, multiple organ failure, metagenomic next-generation sequencing

The inactivation of molybdenum carbide catalysts by water oxidation is a significant problem in the steam reforming of dimethyl ether (SRD) reaction. In this work, the catalytic performance and stability of molybdenum carbide are greatly improved by ceria modification. Ceria leads to the transformation of methoxy to formate instead of methyl formate, which accelerates the reaction, as identified using in situ diffuse reflectance Fourier-transform infrared spectroscopy (DRIFTS). Moreover, the reactant water is preferentially dissociated on ceria and generates hydroxyl groups instead of being directly dissociated on molybdenum carbide. This reduces the long-time intimate contact of the hydroxyl groups with the molybdenum carbide and protects it from being deactivated by water oxidation. This study not only contributes to the research into molybdenum carbide catalysts for the SRD, but also provides a conceptual approach for overcoming the deactivation of carbide catalysts through oxidation in other similar environments.

To improve the stability of molybdenum carbide catalysts in dimethyl ether steam reforming (DSR), the inactivation mechanism and the performance of Pt modified catalyst has been investigated. The Mo2C oxidation induced by H2O is verified to be the main reason of catalytic deactivation. After modified with Pt, the H2 production rate and selectivity are greatly enhanced, reaches 1605 μmol min−1·gcat−1 at 350 °C, in comparison to that of the Mo2C/Al2O3 catalyst. Moreover, the 2%Pt–Mo2C/Al2O3 catalyst is more stable with only 20% activity loss after 50 h on stream compares to the 73% activity loss in 12 h with Mo2C/Al2O3 catalyst. By means of in-situ diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), the enhancement brought by Pt is ascribed to the consumption acceleration of intermediate oxygen species on catalyst surface and the decline of onset temperature of DSR reaction. It is expected that these findings can lead us to more practical molybdenum carbide catalysts in DSR.

In this work, well-ordered platinum (Pt) nanocubes (NCs), with precise control on the size and the spatial arrangement, are synthesized from a microemulsion overgrowth in a block copolymer (BC) nanotemplate. The nanovials on this self-assembled BC template serve as microreactors for the reduction of the HCl/H

Self-assembly of di-blcok copolymers (di-BCs) with precise control on morphologies and structures of nanomaterials makes it a promising technology for catalyst preparation. However, applications of the BC-synthesized Pt nanoparticles (NPs) on fuel cell have less been discussed. The major challenge may be the difficulty in achieving high-density nanopatterns which require a low degree of polymerization but a high effective segment-segment interaction parameter of the BC templates. As a resolution, sequentially double- or triple-layered BC route provides a new density-increased idea of harnessing these materials. In present work, monolayer of ordered and high-dispersed Pt-NP arrays with a density 27-folded has been achieved by the multiple di-BC routes consisted of identical self-assembly and plasma-cleaning processes. The multiplication has been proved to be equivalent to the duplication and oriented translation of the initial Pt-NP arrays, which provides not only a well-defined approach to control the spacing precisely, but also a bottom-up process to synthesize hexagonal-arranged arrays with predicable densities. Electrochemistry shows that the density multiplication has no negative effects on the Pt utilization of the monolayer arrays, and a remarkable ECSA value of ∼114.5 m2 g−1 is found. Further characterization of the monolayer arrays as cathodic catalysts for PEMFC reveals that, neither the ohmic losses nor the mass-transport losses are enhanced after the density multiplication, and the power density of the PEMFC assembled here is significantly higher than that using commercial Pt/C catalysts. All the results demonstrate that the multiple di-BC approach has great potential in preparation of BC-synthesized Pt-NP arrays for fuel cell applications.

To fabricate effective and stable OER electrode in water electrolysis, self-doped TiO2 nanotube arrays which has a higher electrical conductivity than pristine TiO2 nanotube arrays was used as the support for loading IrO2. The self-doped TNTA was fabricated by a simple electrochemical reduction of TNTA in neutral electrolyte solution, and then IrO2 nano particles were deposited by pulse electro-deposition method. The cyclic voltammetric behavior, electrical conductivity and micro structure of self-doped TNTA prepared at different reduction potential were characterized to obtain an optimal performance, and self-doped TNTA prepared under −1.9 V (vs. Ag/AgCl) shows the best electrochemical performance. After depositing IrO2, the OER activity and stability of new electrodes were also determined. Due to the enhanced electrical conductivity of support, the mass activity of IrO2/self-doped TNTA are 50 times higher than IrO2/TNTA. The OER stability of new electrode was evaluated under constant current of 5 mA/cm2, IrO2/TNTA and IrO2/Ti were also tested for comparison. A higher stability of IrO2/self-doped TNTA electrode is observed than the other two electrodes, and XPS studies indicate a lower oxidation state of Ir in IrO2/self-doped TNTA, this shows a possible interactions between IrO2 and the new support.

This work offers a typical understanding of the factors that govern the nanostructures of poly(4-vinyl pyridine)-b-polystyrene-b-poly(4-vinyl pyridine) (P4VP-b-PS-b-P4VP) block copolymers (BCs) in dioxane/water, in which water is a selective solvent for the P4VP block. It is achieved through an investigation of the amphiphilic triblock copolymer micelles by variation of three different factors, including water content (above CWC but under the immobile concentration), temperature (ranging from 20 °C to 80 °C), and copolymer composition (low and high PS block length). Transition of bead-like micelles to vesicles is observed with the increase of water content due to the increase of interfacial energy between the copolymer and the solvent. Effect of temperature superposed on that of water content results in various morphologies, such as beads, fibers, rods, capsules, toroids, lamellae, and vesicles. The interfacial tension between the BC and the solvent increases with the increase of water content but decreases with the increase of temperature, indicating that the micellar morphologies are resulted from the competitive interplay between the temperature and the water content and always change in a direction that decreases the interfacial energy. Based on the micellar structures obtained in this work and the effects of temperature superposed on water concentration, a diagram of phase evolution of different micellar morphologies is illustrated here, covering the temperature range from 20 °C to 80 °C and the water content changing from 20 vol% to 35 vol%. For the investigation of BC composition, morphological transition of vesicle-to-fiber, for high PS length, is observed as compared with bead-to-capsule for low PS length, as the temperature changes from 20 °C to 80 °C. Our research complements the protocols to control over the morphologies and the phase diagram describing P4VP-b-PS-b-P4VP micellar nanostructures in aqueous solution.

This work offers an effective size-controlled synthesis of platinum nanoparticle (Pt NP) arrays for electrocatalyst through self-assembled nanopatterns of block copolymers on titanium (Ti) wafers. Size, spacing and uniformity of Pt NP with loading of Pt to a minimum were investigated to be controlled and adjusted in order to improve the electrochemically active surface area (ECSA) and ECSA stability, and Pt concentration in copolymer/chloroplatinic acid (H2PtCl6) solution was verified to be one of the most important factors to control the arrays’ structure. In our case, the Pt NPs with predictable size of 5–16.5 nm could be obtained when the Pt concentration is larger than 0.05 mg ml−1, which the dominant diameter is proved to be proportional to one-third power of the Pt concentration according to the linear relation of templates’ Pt/N mass ratio versus Pt concentration, and the Pt NPs remain highly ordered arrays with predictable spacing when the Pt concentration is larger than 0.125 mg ml−1. Decrease in Pt concentration from 2 to 0.125 mg ml−1 is an effective method to improve the ECSA and durability simultaneously. The Pt NP arrays exhibit not only a remarkable initial ECSA value of 106.2 m2 g−1, but also a pseudo-zero particle aggregation possibility during 3000-cycle voltammetry, which is attributed to the high Pt NP dispersion and the ordered arrays that improve the Pt utilization and lower the possibility of aggregation.

For a typical Proton exchange membrane (PEM) water electrolysis system, reducing the amount of Ir loading at the anode in membrane electrode assembly (MEA), while maintaining the performance, is still a big challenge. Here, to improve the performance of catalyst layer for oxygen evolution reaction (OER) in an acidic medium, vertical aligned IrOx nanoarrays (IrOx NAs) were synthesized by electrodeposition with TiO2 nanotube arrays (TNTA) as template. By tuning the scan rate in the electrodeposition process, IrOx open-end nanotube arrays with tunable length ranged from 500 nm to 1400 nm and hollow nanorod arrays were obtained due to a diffusion-controlled deposition process. By constructing 3-D electrode of 1-D catalyst with enhanced ion transfer, IrOx NAs performed almost the same current density of OER with 1/20 Ir loading amount compared with commercial IrO2 nanoparticles, which could significantly reduce the cost of catalyst in PEM water electrolyser. Moreover, no apparent current decrease was observed even after 10 h’ anodic polarization under 1.55 V, which exhibit excellent OER durability.

Ordered electrode is believed to be the next generation of MEA. One-dimensional-arrays material possesses high surface area, oriented electron transfer pathway and facile mass transfer pathway, which shows great potential as electrocatalyst. For OER electrode, IrO2 is still the irreplacable choice at present status. To construct IrOx based nanotube/nanowire arrays could increase the performance of OER electrode with reduced loading amount of Iridium. Titanium oxide nanotube arrays (TNTA) is a promising candidate for the preparation of 1-D arrays electrode as its prominent stability, ordered structure and sufficient conductivity with simple modification. In order to achieve the open-end nanotube structure for the fully utilization of noble metal catalyst, controlled electrochemical deposition is applied. In our previous work, IrOx nanotube arrays performs similar current density with 1/20 loading amount of commercial IrO2 nanoparticle at the same potential. To achieve the length control of IrOx nanotube arrays, the electrodeposition of IrOx on TNTA with cyclic voltametry method was studied. By altering the scan rate, continuous IrOx nanotube arrays with different length ranged from 500 nm to 1400 nm was achieved. This phenomenon may probably due to that the deposition in the tube is diffusion controlled, while the deposition at the mouth of TNTA keeps constant due to sufficient supplement of precursor form the bulk electrolyte. In a single cycle, as the depositing goes on, the concentration gradient along the tube forms and results in uneven deposition. Different scan rate results in different duration of depositing in a single cycle. And longer duration means more uneven deposition, and leads to shorter nanotube. At present, to obtain IrOx nanotube arrays with uniform tube wall, control deposition with pulsed potential deposition method is studied. By altering the relaxation and deposition time, IrOx with uniform thickness and tunable length can be achieved. And the thickness of IrOx tube wall can be controlled, too. By achieving uniform and thinner tube wall, the utilization rate of Iridium can be further increased.