查找使用阿拉丁产品的科研文献

Analysis of oligomers in poly (butylene succinate) and poly (butylene adipate-co-terephthalate)

Zhang Chuanhui,Chen Chao,Ouyang Chunping,Zeng Xiangbin,Guo Zhilong,Lai Fenghua,Li Jianjun

Aliphatic and aliphatic–aromatic polyesters are used widely in the food packaging field, which is very concerned about the volatile organic compound (VOC). Typical VOCs in poly (butylene succinate) (PBS) and poly (butylene adipate-co-terephthalate) (PBAT) are oligomers, especially cyclic esters, which were studied using GPC, MALDI-FTICR-MS and UPLC-FTICR-MS technique. Cyclic esters with repeating unit 2–8 were found in PBS; cyclic esters with repeating unit 1–10 (or more) were found in PBAT derived from three monomers with almost all possible random combinations. Cyclic esters with repeating unit 2–4 were the most abundant structures, but only cyclic esters with repeating unit 1–3 were found in the crystalline extracted from the recovered butanediol from the product line. Cyclic esters with repeating unit 1–3 can also be extracted from methanol at 70 °C for 1 h, and the content of linear oligomers increased with increasing temperature to 200 °C. But PBAT resin cannot be decomposed to monomers at 200 °C for 1 h in methanol without other additives. Graphical abstract

Platensimycin-berberine chloride co-amorphous drug system: Sustained release and prolonged half-life

Zhe Wang,Xin Chen,Duanxiu Li,Enhe Bai,Hailu Zhang,Yanwen Duan,Yong Huang

Co-amorphous technology is an emerging approach for pharmaceutical engineering of drugs and drug leads with improved physicochemical properties and bioavailability. Platensimycin (PTM) is a promising natural antibiotic lead that acts on bacterial fatty acid synthase and exhibits excellent antibacterial activity . Despite great strides to improve its poor pharmacokinetics by medicinal chemistry and nanotechnology, there are no convenient oral delivery systems developed. Here, a co-amorphous system of PTM and berberine chloride (BCL) was developed for oral delivery of PTM. Co-amorphous PTM-BCL was prepared by rotary vacuum evaporation method, and systematically characterized by powder X-ray diffraction, temperature modulated differential scanning calorimetry , Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS). Compared with PTM or BCL alone, the equilibrium solubility and dissolution rate of both of them in the co-amorphous systems decreased significantly, showing the characteristics of sustained release . The molecular interactions between PTM and BCL were mediated by strong charged-mediated hydrogen bonds , based on FTIR, XPS, and NMR-based techniques. The co-amorphous PTM-BCL system showed excellent physiochemical stability at room and elevated (40 °C) temperature under dry conditions. The combination of PTM and BCL showed increased killing of a clinical isolated methicillin-resistant Staphylococcus aureus strain in killing checkerboard assays. Finally, co-amorphous PTM-BCL exhibited 2- or 3-fold longer half-life in rats than that of crystalline and amorphous PTM upon oral administration, respectively. Our study suggests a rational approach to realize the full potential of potent antibiotic PTM, which may be conveniently adapted for engineering of other important pharmaceutics.

Preparation of poly(acrylamide-co-Acrylonitrile) thermosensitivity microgel and control release of aspirin

Shuwei Cai,Xian Li,Shijie Pu,Xinyu Ma,Xianru He

Co3O4/Co nano-heterostructures embedded in N-doped carbon for lithium-O2 batteries

Lei Ding,Tianyue Huang,Dawei Zhang,Pan Qi,Lihao Zhang,Cong Lin,Hao Luo

Rational design and synthesis of high-performance bifunctional oxygen electrocatalysts with increased effective active sites and facilitated mass/electron transfer are in demand for the lithium-oxygen batteries (LOBs) to overcome the sluggish oxygen reduction/evolution kinetics. Herein, a simple yet effective strategy is proposed by annealing the Prussian blue analog (PBA) precursor under altered calcination conditions to achieve the efficient nano-heterojunction catalysts with optimized active sites. As a result, the obtained porous Co 3 O 4 /Co nano-heterostructures embedded in N-doped graphitized carbon matrix (Co 3 O 4 /Co@NC) exhibit outstanding electrochemical performance with a high specific capacity of 22,156 mA h g −1 at the current density of 100 mA g −1 and excellent stability, obviously superior to the LOBs based on the other single-component catalysts. Systematic investigations suggest that the enhanced electrochemical performance is ascribed to the Co 3 O 4 /Co nano-heterostructure interface and the N-doped porous carbon matrix. This study presents a simple and effective approach for boosting the PBA-derived catalysts with efficient reactivity for various catalytic applications.

ZIF-67 derived Co/N carbon hollow fiber membrane with excellent decontamination performance

Jia Xie,Yingpeng Yang,Hao Zhang,Saisai Chen,Zhengjun Lv,Yujun Zhou,Junwen Qi,Xiuyun Sun,Jiansheng Li

Advanced oxidation processes (AOPs) were appealing wastewater treatment options yet practices were hampered by reactor design and diminished performance in complex water matrices. Herein, one-step-pyrolysis strategy was proposed for large-scale synthesis of ZIF-67 derived conductive Co/N carbon hollow fiber ultrafiltration membrane to achieve exceptional availability of catalytic sites and interference prevention from macro molecular substances by size exclusion. Benefitting from the microenvironment modulation and electric field assistance (−1 V, membrane as the cathode), the bisphenol A (as a model micropollutant) can be efficiently removed with enhanced mass transfer of flow-through process (modified apparent reaction rate constant of 1260 μM g cat -1 s −1 ) and the active cobalt species were cycled via electroreduction thus showing exceptional sustainability with nearly zero Co leaching even after 24 h operation. The synergy effects between separation and catalysis alleviated the deteriorated AOPs efficiency and membrane fouling caused by macromolecular organic matter. The integrated membrane system provides new insight into rational design of catalytic membrane and system engineering for advanced water purification.

Photocatalyst CdS for efficient cleavage of lignin CO bonds in micellar aqueous medium

Jie Xu,Feng Lin,Jingyu Wang,Yujie Wang

Photocatalytic cleavage of lignin C O bonds is a promising way to depolymerize lignin into aromatic value-added chemicals. However, the dispersibility of lignin in solvents and photocatalytic efficiency still face great challenges. Here, a micelle aqueous medium (CTAB-15) composed of hexadecyl trimethyl ammonium bromide and water was successfully prepared. 2-phenoxy-1-phenylethanol (lignin model compounds, PPol) and dioxanesolv poplar lignin have a good dispersion in CTAB-15. Compared to the previous reports, the highest photocatalytic efficiency can be obtained under optimal conditions by using the photocatalyst CdS. The main products formed by photocatalytic cleavage of lignin C O bonds are phenols and ketones. Mechanism studies show that CTAB-15 can provide sufficient hydrogen by photo-driven dissociation of water for photocatalytic cleavage of lignin C O bonds, which is critical to rapidly improving photocatalytic efficiency. The hydrogen, which is used to form acetophenone, comes from H 2 O and PPol. However, the hydrogen needed to form phenol comes only from PPol itself. In addition, the photocatalytic reaction follows a photogenerated electron-hole coupled redox process. This work develops a new direction for promoting the high-value utilization of lignin.

Growth, structure and upconversion properties of Yb3+ and Er3+ co-doped Gd3Sc2Al3O12 crystal

Hao Ren,Shoujun Ding,Hongyuan Li,Wenpeng Liu,Yong Zou,Yufeng Han,Qingli Zhang

Upconversion luminescent materials exhibit excellent near-infrared to visible conversion properties that make them crucial for optoelectronics , visible display devices, and biological labels. Herein, we report a high-quality Yb 3+ and Er 3+ co-doped Gd 3 Sc 2 Al 3 O 12 ( GSAG) single crystal which was grown successfully by the traditional Czochralski method with Er 3+ and Yb 3+ doping concentration of 1 at.% and 10 at.%, respectively. The structure parameters of the crystal were observed by the X-ray Rietveld refinement method. In addition, the transmission and upconversion emission properties of the crystal were analyzed at room temperature . The 940 nm excited upconversion energy transfer mechanism and dependence of the green-to-red upconversion intensity ratio ( I g/r ) on pump power were investigated. A dominant two-photon absorption process of the green and red upconversion emission bands were revealed in Yb,Er:GSAG crystal. The results indicate the crystal is a promising upconversion single crystalline material.

Catalytic ozonation with biogenic Fe-Mn-Co oxides: Biosynthesis protocol and catalytic performance

Anlin Xu,Siyan Fan,Tong Meng,Ren Zhang,Yunhai Zhang,Shunlong Pan,Yongjun Zhang

Metal oxides, as a popular group of ozonation catalyst, are usually synthesized with physiochemical protocols involving hazardous materials and extreme conditions. In this study, a biological method was studied with manganese oxidizing bacteria Pseudomonas sp. to synthesize multi-metal oxides consisting of iron, manganese, and cobalt (Bio-FeMnCoOx) to catalyze ozonation for the first time. It was found that the dosage of cobalt, the cultivation time, and the polishing methods could significantly impact the catalytic activities of degrading benzotriazole as a model. The second-order degrading kinetic constant with optimized Bio-FeMnCoOx was 4.8 times that with the physiochemically synthesized peer. The activity of Bio-FeMnCoOx was compared with other reported catalysts in terms of Rct value. The quenching tests and EPR spectra indicated the participation of hydroxyl radicals, superoxide radicals, and singlet oxygen. The study demonstrates the great potential of biosynthesis as a green protocol for preparing metal oxides to efficiently catalyze ozonation.

Hierarchical Co(OH)F/CoFe-LDH heterojunction enabling high-performance overall water-splitting

Mingliang Qin,Yamei Wang,Huaming Zhang,Muhammad Humayun,Xuefei Xu,Yanjun Fu,Marsil K. Kadirov,Chundong Wang

Due to the serious energy and environmental issues, hydrogen generation via water splitting has been regarded as a green and promising alternative strategy to the use of fossil fuels. Developing highly efficient and non-noble metal based dual-functional electrocatalysts for overall water splitting to generate hydrogen and oxygen has become more critical. In order to fulfill the requirements of efficient hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), herein, we report novel hierarchical Co(OH)F@CoFe-LDH heterostructured nanorod arrays fabricated via a facile two-step approach. The resultant Co(OH)F@CoFe-LDH displays exceptional electrocatalytic OER and HER activity with a small overpotential of 240 mV and 130 mV at 10 mA cm−2, respectively. Further, the electrocatalyst revealed excellent long-term stability during a recyclability test for 37 h. The superior performance of Co(OH)F@CoFe-LDH can be attributed to the synergistic effect at the interface of the Co(OH)F nanorods and the covered CoFe-LDH nanosheets. Meanwhile, Co(OH)F@CoFe-LDH as a water electrolyzer to produce a current density of 10 mA cm−2 requires a small voltage of 1.58 V. This work paves the way for the design and construction of low cost and highly efficient 3D hierarchical electrodes for practical applications in electrocatalysis.

Influence of Ru on the microstructure and performance of WC-Co cemented carbides

Hong Zeng,Wenbin Liu,Chongbin Wei

This study investigated the microstructure and properties of cemented carbides before and after the addition of Ru. The hardness and elastic modulus of the binder phase of Ru-containing cemented carbides were higher, and the hardness at room temperature and high temperature were also high. In particular, the oxidation resistance of Ru-containing cemented carbides was enhanced at high temperatures. Therefore, the solid solution-strengthening effect of the binder phase containing Ru was significant, which was conducive to the improvement of the high-temperature hardness and enhancement of the high-temperature characteristics of the alloy.

MoSe2 nanosheets decorated Co/C fibrous composite towards high efficiency electromagnetic wave absorption

Xiu-Zhi Tang,Zijian Liao,Haolong Shi,Rong Wang,Jianling Yue,Xuelong Chen

Electromagnetic wave (EMW) absorption materials have recently received considerable attention due to the increasingly severe EMW pollution. It remains challenging to fabricate a lightweight absorber with high absorption performance and low matching thickness via structure design and composition tuning. Herein, one type of fibrous composite EMW absorber with two-dimensional (2D) nanosheets coating was synthesized by electrospinning, pyrolysis and hydrothermal. The combination of cobalt nanoparticle and carbon nanofiber with decoration of 2D MoSe 2 nanosheets on the surface significantly promote the EMW absorption through dielectric/magnetic loss, impedance matching, diverse polarizations and porous structure induced multiple scattering. Owing to the coupling effect of proper combination of multiple components and hierarchical structure, a strong EMW absorption with minimum reflection loss (RL) −62.30 dB at 10.70 GHz, effective absorption bandwidth (EAB) 5.10 GHz (9.30–14.40 GHz) covering most of the X-band was achieved with absorber thickness of 2.05 mm. By adjusting the thickness to 1.60 mm, the EAB can reach 6.00 GHz (12.00–18.00 GHz), covering the whole Ku bands. This composite fibrous absorber with excellent EMW absorption performance is promising to be used in many EMW attenuation applications.

Enhanced electrocatalytic hydrogen evolutions of Co(II)phthalocyanine through axially coordinated pyridine-pyrene

Tingting Gu,Isaac Kwaku Attatsi,Weihua Zhu,Minzhi Li,Samuel A. Ndur,Xu Liang

Non-precious metal catalysts can effectively evolve hydrogen in aqueous media, but a highly efficient metal-based catalyst is still a significant assignment. Herein, Co(II)phthalocyanine was noncovalently immobilized on multiwalled carbon nanotubes through axial coordination via pyridine-pyrene linker and applied towards hydrogen evolution reactions. This material provided a superiorly enhanced electrocatalyzed performance signifying high efficiency. With this behaviour, our target material we believe paves the way towards designing efficient energy production and storage devices.