POLYMER TESTING
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2020
·
IF 3.275
Lidong Feng,Sheng Xiang,Yanlong Liu,Xinchao Bian,Gao Li,Xuesi Chen
An analytical method was developed to quantitatively determine residual monomers, namely, lactide (LA) and ε -caprolactone (CL), in poly(lactide- co - ε -caprolactone) (PLCL) using an internal-standard method of gas chromatography (GC). PLCL and diphenyl ether (DPE) as an internal standard were initially dissolved in dichloromethane (DCM), and then PLCL was precipitated in cyclohexane. The residual LA and CL monomers in PLCL, as well as DPE, were extracted into cyclohexane from the polymer solution. The resulting solution was directly injected into a GC system. This method was practical for measuring the residual LA and CL contents in PLCL. The relative standard deviation ( RSD ) ( n = 5) denoting the repeatability of this method was less than 5.6% and 4.3% for the LA and CL measurements, respectively, indicating that the method was sufficiently precise. The recovery rate of standard addition was 96.5%–101.5% and 98.4%–104.2% for the determination of LA and CL in PLCL, respectively. The RSD of the recovery of standard addition ( n = 5) was not more than 2.0%, indicating that the method was sufficiently accurate.
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高影响因子
JOURNAL OF THE AMERICAN CERAMIC SOCIETY
·
2020
·Vol. 104
·期 6
·2860-2867
·
IF 3.502
Da-Wang Tan,Zhen-Yong Lao,Zhan Zhang,Wei-Ming Guo,Shi-Kuan Sun,Hua-Tay Lin
B 4 C-TiB 2 ceramics (TiB 2 ranging 5~70 vol%) with Mo-Co-WC as the sintering additive were prepared by spark plasma sintering. In comparison with B 4 C-TiB 2 without additive, the enhanced densification was evident in the sintered specimen with Mo-Co-WC additive. Core-rim structured grain was observed around TiB 2 grains. The interface of the rim between TiB 2 and B 4 C phases demonstrated different feature: the inner borderline of the rim exhibited a smooth feature, whereas a sharp curved grain boundary was observed between the rim and the B 4 C grain. The formation mechanism is discussed: the epitaxial growth of (Ti,Mo,W)B 2 rim around the TiB 2 core may occur as a result of the solid solution and dissolution-precipitation between TiB 2 phase and the sintering additive. It was revealed that the fracture toughness increased as the content of TiB 2 content increased, alongside the decreased hardness. B 4 C-30 vol% TiB 2 specimen demonstrated the optimal combination of mechanical properties, reaching Vickers hardness of 24.3 GPa and fracture toughness of 3.33 MPa·m 1/2 .
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高影响因子
Optoelectronics Letters
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2020
·Vol. 16
·期 5
·355-359
·
IF 0
Bian Ming-jing,Zhang Hong-yan
In this work, we studied the effect of different pH values on morphology, band gap and photoluminescence (PL) properties of Eu 3+ /Tb 3+ co-doped ZnO prepared by coprecipitation method. Experimental results show that alkaline condition is more favorable for the doping of Eu 3+ and Tb 3+ ions which reduce the band gap and increases the PL intensity of UV emission (385 nm) and visible emission (400—600 nm) of ZnO. Gaussian deconvolution PL spectra show that the defects on the surface of ZnO are decreased when it is synthesized under alkaline conditions. Furthermore, both the intrinsic orange emission of Eu 3+ ions (611 nm) and the intrinsic green emission of the Tb 3+ ions (495 nm) of ZnO in this case are obtained at the same time. High intensity green and orange emission indicates that Eu 3+ /Tb 3+ co-doped ZnO is a promising PL material and has potential in emission devices.
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JOURNAL OF MEMBRANE SCIENCE
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2020
·
IF 7.183
Chengyu Yang,Weixing Xu,Yang Nan,Yiguang Wang
Solvent-resistant nanofiltration (NF) membranes have numerous application prospects. In this study, a novel solvent-resistant nanofiltration membrane with a double layered polyamide structure was prepared for efficient desalination. The substrate was polyimide crosslinked with m -phenylenediamine (MPD), and the surface layer was polyamide prepared by typical interfacial polymerization. The crosslinking was confirmed by Fourier transform infrared spectroscopy . Investigation of the effects of different reaction conditions on membrane performance showed that the optimal reaction conditions were found to be: 5% aqueous MPD solution with crosslinking time of 10 min and piperazine concentration of 0.1% (m/v). The rejection rate for sodium sulfate and sodium chloride were 99.13% and 97.45%, respectively. The membrane morphologies were studied by scanning electron microscopy and atomic force microscopy . The membrane showed electronegativity in the pH range of 3.0–10.0 and its contact angle was 54.28°, indicating excellent hydrophilicity. After soaking in several solvents for a week, the membrane still had a high rejection rate of more than 90% for Na 2 SO 4 , demonstrating its excellent solvent resistance .
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INTERNATIONAL JOURNAL OF HEAT AND MASS TRANSFER
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2020
·
IF 4.947
Xiu Li,Yimin Xuan,Qiang Li
Conventional microchannels provide effective chip cooling with constant flow rate and this comes at the cost of high pumping power consumption. Considering the dynamic heat load in reality, a self-adaptive microchannel cooling is desired for regulating the flow rate to diminish the operational cost while preserving the inherent cooling effectiveness. Taking the advantages of easy synthesis, well tunable lower critical solution temperature (LCST) and remarkable mechanical strength, this paper reports the self-adaptive microchannel cooling with the thermal-sensitive nanocomposite (NC) P(MEO 2 MA- co -OEGMA) hydrogel. A novel route is developed to integrate the hydrogel with the chip using template-aided imprint molding and in situ polymerization. Circular hydrogel is elaborately designed and anchored firmly in the channel. The cooling performance is tested with a custom test vehicle under different operating conditions. The hydrogel acts as a smart valve and tailors the flow rate from 0.14 mL/s to 0.46 mL/s based on heat load variation. Compared with conventional channels, heat flux of 100 W/cm 2 can be extracted with similar temperature rise while the coefficient of performance (COP) is improved by an order of magnitude. The transient characteristics and repeatability are also validated. The self-adaptive scheme offers both effective and economical liquid cooling for modern electronic devices.
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Crystals
·
2020
·Vol. 10
·期 10
·922
·
IF 2.404
Xiao Juan Liu,Yang Zhang,Xue Zhong Wang
In situ ATR-FTIR spectroscopy and imaging and image analysis were applied to the study of the multicomponent co-crystallization process involvingS-valsartan and sacubitril in which LCZ696 crystals were formed. LCZ696 is a combination drug for use in heart failure that was approved by the FDA in 2015 following development by Novartis Pharmaceuticals. Though much work was reported on LCZ696 about its pharmacokinetic and pharmacodynamic effects in the evaluation and clinical testing, less attention was paid to study on the co-crystallization process. LCZ696 crystals have shown difficulties in filtration mainly due to the small particle size. In this work, LCZ696 crystals were prepared successfully byS-valsartan and sacubitril, and characterized by SEM, XRPD, TG-DSC and ATR-FTIR. ATR-FTIR and imaging and image analysis were used to monitoring solution concentration and investigating the co-crystallization mechanism. It revealed that the nucleation process was very slow compared with the transformation process, which is indication that the co-crystallization was controlled by nucleation. LCZ696 crystals are composed of very thin hexagonal plates, which seems indicating that LCZ696 crystals grow mainly in two size dimensions. Stirrer speed and crystal seeds were found to have noticeable effect on the induction time, transformation time and crystal size distribution. The Johnson-Mehl-Avrami equation was found to be able to describe the co-crystallization process.Keywords:S-valsartan and sacubitril co-crystallization;LCZ696;ATR-FTIR;On-line process imaging
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JOURNAL OF MATERIALS SCIENCE & TECHNOLOGY
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2021
·
IF 8.067
Guanglu Li,Chang Liu,Zhao Zhang,Baihua Cui,Yanan Chen,Yida Deng,Wenbin Hu
Oxygen evolution and oxygen reduction are considered as essential processes in the energy conversion devices. The progress of cost-effective bifunctional catalysts has become a critical issue to be solved. Here, we report that Co(OH) 2 @N-doped carbon (NC) was facilely synthesized through the impregnation strategy of metal-organic frameworks derived carbon and cobalt ions. N-doped carbon with porous structure and cobalt hydroxide nanosheets play a synergistic effect role, representing excellent catalytic performance toward oxygen evolution and reduction reactions. The obtained Co(OH )2 @NC exhibits remarkable activity in terms of a lower overpotential of 330 mV@10 mA cm −2 for OER and a more positive half-wave potential (E 1/2 = 0.84 V) for ORR in alkaline medium, outperforming IrO 2 and Pt/C. Due to its superior bifunctional catalytic performance, Co(OH) 2 @NC catalyst is applied into a promising air electrode of Zn-air battery. This presented strategy of impregnation synthesis in this work provides a new design direction for practical electrochemical energy devices.
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高影响因子
INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH
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2020
·
IF 3.573
Benyong Yang,Wentao Mu,Benedict Tsz Woon Lo,Sijie Liu,Zhihang Chen,Liam John France,Xuehui Li
NOx and CO formation is, at present, a consequence arising from fuel production, but their emission need not be. In this study, a series of novel Ir-containing TiO2-nanobelt catalysts were designed and prepared for the simultaneous removal of NOx and CO. Activity data demonstrates that the TiO2(B) support promotes NO reduction compared to anatase. Furthermore, reaction efficiency (RE), a measure of NOx consumption vis-à-vis that of CO, reveals that catalysts containing anatase promote CO oxidation more so than their TiO2(B) counterparts. Increasing Ir concentration over the latter promotes low-temperature catalytic performance, an effect believed to be linked to the formation of Ir0–IrO2 composites. In situ DRIFTS experiments reveal the relevance of nitrite/nitrate formation and consumption at 250 °C, a mechanism insinuated by the RE value. However, at 300 °C, both TOF and RE increase, signifying the participation of a faster and more-selective reaction, which appears consistent with the isocyanate-mediated pathway.
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SEPARATION AND PURIFICATION TECHNOLOGY
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2020
·
IF 5.774
Yifei Wang,Junjie Gu,Ayang Zhou,Aiqun Kong,Muntadher M. Alwan Almijbilee,Xiaokuo Zheng,Jinli Zhang,Wei Li
A novel poly[acrylate-co-amide] network composite nanofiltration membrane was synthesized via the photopolymerization on the top of amine-terminated polyetherimide using the photoinitiator BP and the monomers of TPGDA and PETA, of which the void size in the toplayer network can be modulated via a solvent immersion. The synthesized UV-15T2P-11 network membrane showed the permeance of 7.1 L m −2 h −1 MPa −1 and SBB rejection of 95% in THF. Then, molecular simulations suggested that DMF immersion can make the void size in the membrane toplayer increased from the pristine 1.0 nm to 1.7 nm. DMF-activated membrane p-UV-15T2P-11 shows excellent performance and long-term stability, with the permeance of 13.2 L m −2 h −1 MPa −1 and the SBB rejection of 91% in THF. These results illustrate that the photopolymerized network polymers combined with solvent activation are promising materials to manufacture organic solvent nanofiltration membranes.
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MATERIALS CHEMISTRY AND PHYSICS
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2020
·
IF 3.408
Huimin Guo,Chao Li,Hongxin Hu,Xiaoyan Yu,Kimiyoshi Naito,Qingxin Zhang
Nanodiamonds are novel carbon nanoparticles , which have wide application prospect around various fields owing to the excellent properties. However, nanodiamonds exhibit great tendency to aggregate and this phenomenon extremely limits the application of nanodiamonds. Two simple and green approaches of “grafting from” and “grafting to” are conducted to modify nanodiamonds covalently with copolymer of poly(ϵ-caprolactone) and polyethylene glycol . The characterizations of FT-IR, Raman spectra and TGA indicate that the copolymers are covalently linked on nanodiamonds surface through “grafting from” and “grafting to” methods successfully and the grafting rates are 13.35% and 20.87%, respectively. Moreover, the modified nanodiamonds present smaller particle diameter, less aggregation and better dispersion in organic solvent according to the dynamic light scattering particle size analyzer, transmission electron microscopic analysis and natural sedimentation experiment, which may have potential application at many fields.
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POLYMER COMPOSITES
·
2020
·Vol. 41
·期 9
·3817-3829
·
IF 2.265
Mengjie Zhang,Liu Liu,Lin Jin,Lihao Sun,Ming Li,Lei Shang,Yu Liu,Yuhui Ao
To improve interfacial adhesion between carbon fiber (CF) and epoxy resin, a low-cost and environment-friendly method was developed to treat the CF surface via the bio-inspired co-deposition of catechol (Cc) and polyethyleneimine (PEI). It is noteworthy that the deposition process reacts at room temperature with water as solvent, and does not require harsh conditions or the use of toxic reagents. After treatment, the CF/epoxy composites were endowed with excellent mechanical properties and showed increases of 51.9% and 51.7% for flexural strength and ILSS, respectively, in comparison with unsized CF laminates. The analyses of fractured surface morphologies and strengthening mechanism of the composites indicated that the uniformly coated Cc-PEI on the fiber surface can promote the diffusion and entanglement of the matrix molecular chains and form chemical bonding as well as π-π stacking, thus effectively improving the interfacial adhesion. In addition, the facile process disclosed in this study can provide a new strategy to not only for CF treating but also expected to be used in the modification of other high performance fiber reinforcement and industrial applications.
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COLLOIDS AND SURFACES B-BIOINTERFACES
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2020
·
IF 4.389
Xingwang Qie,Minghui Zan,Li Li,Ping Gui,Zhimin Chang,Mingfeng Ge,Ruo-Song Wang,Zhenzhen Guo,Wen-Fei Dong
Assessment of microbial viability plays a key role in human health protection. Optical imaging based on fluorescent dyes is a simple and convenient way to assess microbial viability. However, it is still a challenge to obtain stable, nontoxic and low-cost dyes. Herein, we prepared a nitrogen and phosphorus co-doped carbon nanodots (N, P-CDs) via a one-step solvothermal method. The prepared CDs possess plenty of functional groups and exhibit high stability, good biocompatibility, excellent photoluminescent and low toxicity. Especially, the properties of high quantum yield (89.9%) and highly negative surface charge (−41.9 mV) make the prepared N, P-CDs ideal materials for microbial differentiation. Compared with commercial dyes, our CDs are more stable, cost less, which can rapidly distinguish dead microorganisms from living ones with higher specificity.
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PubMed
高影响因子
危险品化学品经营许可证（带存储）