查找使用阿拉丁产品的科研文献

Preparation and properties of an organic–inorganic composite superabsorbent based on attapulgite

Guofu Ma,Feitian Ran,Enke Feng,Zhe Zhang,Ziqiang Lei

A novel, low-cost, and eco-friendly organic–inorganic composite superabsorbent is successfully prepared in aqueous solution by graft copolymerization of partially neutralized acrylic acid (AA), polyvinyl alcohol (PVA), and attapulgite (APT) using ammonium persulfate (APS) as an initiator and N,N-methylenebisacrylamide (MBA) as a crosslinker. The structure and morphology of the composite superabsorbent are characterized by means of Fourier transform infrared, X-ray diffraction, field-emission scanning electron microscopy, and transmission electron microscopy. The effects of APT content which can affect the water absorbency and the pH, ionic surfactants and different saline solution which can affect swelling capabilities of the composite superabsorbent are also investigated. The results show the composite superabsorbent give the best absorption up to 680 g/g and 53 g/g in distilled water and 0.9 wt% NaCl solution, high water absorbency over a wide pH range of 4–10, high swelling capacity in anionic surfactant than that of cationic solution, which makes it promising for potential applications in modern agriculture and horticulture. On the other hand, the composite superabsorbent can be used for removing multivalent metal ions.

An Ultra-Stretchable Sensitive Hydrogel Sensor for Human Motion and Pulse Monitoring

Bin Shen,Jiang Li,Yongtao Tang,Huihua Xu,Fengyu Li

Ionic hydrogels with intrinsic conductivity and stretchability show great potential in flexible electronics. However, it remains a great challenge to achieve hydrogels with mechanical stretchability, ionic conductivity, optical transparency, and a self-healing ability at the same time. In this paper, we developed a hydroxyethylidene diphosphonic acid (HEDP) assisted poly(vinyl alcohol) (PVA) composite hydrogel to achieve high-performance stretch-sensitive sensor. Through a facile freeze–thaw strategy, the hydrogel could achieve large stretchability (up to 950% strain), good conductivity (10.88 S/m), excellent linear sensitivity (GF = 2.72, within 100% strain), high transparency, and significant self-healing ability. The PVA-HEDP hydrogel-based strain sensor is capable of monitoring various human movements from small scale (e.g., laryngeal vibration while speaking) to large scale (e.g., knee joint movement). Moreover, the multisite sensor array is capable of detecting the subtle differences between the pulse wave features from Cun, Guan and Chi positions, mimicking the three-finger palpation in Traditional Chinese Medicine. This work demonstrates that the composite hydrogel-based flexible sensor provides a promising solution for multifunctional human activities and health monitoring.Keywords:flexible sensor;conductive hydrogel;sensitivity and linearity;motion and pulse monitoring

Synthesis of reduced graphene oxide by an ionothermal method and electrochemical performance

Changdong Gu,Heng Zhang,Xiuli Wang,Jiangping Tu

An easy ionothermal method is proposed to deoxygenate graphene oxide (GO) for preparation of graphene by using a choline chloride (ChCl)/urea mixture-based ionic liquid. In the synthesis process, the urea portion in the ionic liquid breaks up to release NH3 at around 100 °C. This reacts with the oxygen functional groups of the GO sheets, leading to the formation of graphene. The ionothermal method is an environmentally-friendly and attractive strategy for reducing GO because both ChCl and urea are naturally biocompatible compounds. X-Ray photoelectron spectroscopy indicates that nitrogen atoms can be doped into the graphene skeleton accompanied by the reduction of GO. As an electrode for an electrochemical double layer capacitor in aqueous KOH, the ionothermally reduced GO exhibits a gravimetric capacitance of 155 F g−1 at a current density of 0.2 A g−1 and good cycling performance, which is comparable to the hydrazine reduced GO. We expect that the ionothermal method will have implications for the use of ionic liquids in the large-scale synthesis of graphene-based materials.

An ammonia-based etchant for attaining copper nanoclusters with green fluorescence emission

Hao-Hua Deng,Ke-Lin Li,Quan-Quan Zhuang,Hua-Ping Peng,Qiong-Qiong Zhuang,Ai-Lin Liu,Xing-Hua Xia,Wei Chen

Luminescent copper nanoclusters (CuNCs) constitute a very active research topic due to their unique properties and lower cost than gold and silver NCs. In this study, we report a new, facile, and rapid top-down etching method for synthesizing luminescent CuNCs, using Cu nanoparticles (CuNPs) as the precursor and ammonia (NH3) as the etchant. The etching mechanism is systematically investigated and the optical and structural properties of the obtained CuNCs are carefully studied. The NH3-triggered etching process is very fast and the newly generated CuNCs can emit strong green fluorescence with a high quantum yield. Moreover, by coupling the urease-catalyzed hydrolysis of urea with the NH3-induced etching of CuNPs, we developed a novel fluorescence turn-on assay for urea. The linear range for urea detection is from 0.25 to 5 mM, and the limit of detection is 0.01 mM. This novel sensing approach, with good sensitivity and excellent selectivity, is then successfully utilized to detect urea in human serum samples, demonstrating its great potential in clinical diagnosis. In addition, the proposed coupling method can be extended to monitor other analytes that influence the size-focusing etching process, allowing metal NCs to be used to construct diverse chemosensors and biosensors.

An Injectable Nanocomposite Hydrogel for Potential Application of Vascularization and Tissue Repair

Ding Yilei,Zhao An-sha,Liu Tianmei,Wang Ya-nan,Gao Yuan,Li Jing-an,Yang Ping

In this contribution, an injectable hydrogel was developed with chitosan, gelatin, β-glycerphosphate and Arg-Gly-Asp (RGD) peptide: this hydrogel is liquid in room temperature and rapidly gels at 37 °C; RGD peptide promises better growth microenvironment for various cells, especially endothelial cells (EC), smooth muscle cells (SMC) and mesenchymal stem cells (MSC). Both stromal cell-derived factor-1 (SDF-1) nanoparticle and vascular endothelial growth factor (VEGF) nanoparticles were loaded in the injectable hydrogel to simulate the natural nanoparticles in the extracellular matrix (ECM) to promote angiogenesis. In vitro EC/SMC and MSC/SMC co-culture experiment indicated that the nanocomposite hydrogel accelerated constructing embryonic form of blood vessels, and chick embryo chorioallantoic membrane model demonstrated its ability of improving cells migration and blood vessel regeneration. We injected this nanocomposite hydrogel into rat myocardial infarction (MI) model and the results indicated that the rats heart function recovered better compared control group. We hope this injectable nanocomposite hydrogel may possess wider application in tissue engineering.

Preparation and simultaneous adsorption of an organobentonite towards phenol and Cr(VI)

Ruihua Huang,Bo Wang,Bingchao Yang,Dongsheng Zheng,Zengqiang Zhang

An adsorbent was prepared from bentonite modified by hexadecyltrimethylammonium bromide (HDTMAB) and N-2-hydroxypropyl trimethyl ammonium chloride chitosan (HTCC). This adsorbent was named as HDTMAB–HTCC bentonite. It would be used for the simultaneous adsorption of phenol and Cr(VI) from aqueous solution. By the method of single-factor experiment, the optimum preparation conditions of HDTMAB–HTCC bentonite were obtained. For bentonite (5 g), 1.0 g HDTMAB and 0.5 g HTCC were adopted as the modifying reagents. The reaction was carried out for 2 h at 80°C. The removals towards phenol and Cr(VI) enhanced with the increase in the amount of adsorbent dosage. The relatively high removals towards phenol and Cr(VI) occurred at a pH value of 1.5 or so. During the simultaneous adsorption process of phenol and Cr(VI), phenol was adsorbed by the partition from the organic phase formed by HDTMAB, while Cr(VI) was mostly adsorbed by the electrostatic interactions between HTCC and Cr(VI). No direct competition was observed due to different adsorption sites.

An Integrated Paper-Based Microfluidic Device for Real-Time Sweat Potassium Monitoring

Bo Liang,Qingpeng Cao,Xiyu Mao,Wenhao Pan,Tingting Tu,Lu Fang,Xuesong Ye

Fabricating an Electrospray Ionization Chip Based on Induced Polarization and Liquid Splitting

Lvhan Zhou,Qian Zhang,Xiangchun Xu,Xinming Huo,Qian Zhou,Xiaohao Wang,Quan Yu

The coupling of the microfluidic chip to mass spectrometry (MS) has attracted considerable attention in the area of chemical and biological analysis. The most commonly used ionization technique in the chip–MS system is electrospray ionization (ESI). Traditional chip-based ESI devices mainly employ direct electrical contact between the electrode and the spray solvent. In this study, a microchip ESI source based on a novel polarization-splitting approach was developed. Specifically, the droplet in the microchannel is first polarized by the electric field and then split into two sub-droplets. In this process, the charge generated by polarization is retained in the liquid, resulting in the generation of two charged droplets with opposite polarities. Finally, when these charged droplets reach the emitter, the electrospray process is initiated and both positive and negative ions are formed from the same solution. Preliminary experimental results indicate that the coupling of this polarization-splitting ESI (PS-ESI) chip with a mass spectrometer enables conventional ESI-MS analysis of various analytes.Keywords:microfluidic chip;mass spectrometry;electrospray ionization;induced polarization

Effect of Glycerol on an N-Vinylpyrrolidone-Based Photopolymer for Transmission Holography

Huishi Pi,Weiping Li,Zhiwei Shi,Haining Chen,Xiaoyu Jiang

N-vinylpyrrolidone (NVP) has a large molecular structure, so it is difficult to diffuse during holographic recording, especially at low spatial frequencies. We used glycerol to promote the diffusion of NVP, and successfully improved the holographic performance of the photopolymer at low spatial frequencies. As the concentration of glycerol increases, the holographic performance first increases and then remains stable. The optimal concentration of glycerol is 0.21 mol/L. At this concentration, the maximum diffraction efficiency of the photopolymer is 84%, the refractive index modulation is 1.95 × 10−3, and the photosensitive sensitivity is 7.91 × 10−4cm2/mJ. Compared with the control group, the maximum diffraction efficiency, maximum refractive index modulation and photosensitivity at low spatial frequencies (800 lp/mm) have increased by 11.19 times, 4.69 times and 1.71 times, respectively. Using the optimized photopolymer for transmission holographic recording and reproduction, we have obtained a clear and bright transmission hologram. The photopolymer modified with glycerol is expected to be applied to the fields of holography, diffractive optics, and so on.Keywords:transmission holography;photopolymer;polymerization rate;diffusion rate;diffraction efficiency

Temperature-dependent synthesis of Pd@ZIF-L catalysts via an assembly method

Hong Jiang,Songlin Xue,Yefei Liu,Weihong Xing,Rizhi Chen

The Pd@ZIF-L catalysts with uniform crosshair-star shape and a size of about 20 μm were synthesized by an assembly method, in which a two-dimensional layered zeolitic imidazolate framework-L (ZIF-L) was used as the support to immobilize Pd nanoparticles . Their catalytic activities were evaluated by the catalytic reduction of p -nitrophenol to p -aminophenol. The results highlight that the physical-chemical and catalytic properties of the Pd@ZIF-L catalysts are greatly affected by the synthesis temperature. The temperature variation can make the catalysts transform from two-dimensional flakes to zero-dimensional spheres. High temperature is beneficial for increasing Pd loading and encapsulating Pd nanoparticles within the ZIF-L matrix. However, under the temperature larger than 30 °C, the dense dia(Zn) structures are formed. Increasing Pd loading in the Pd@ZIF-L catalysts leads to a significantly higher p -nitrophenol conversion. The relative dense structure of the as-synthesized catalysts makes p -nitrophenol access the active centers difficultly and a lower catalytic activity is observed. These findings would aid the development of high-performance Pd@ZIF-L catalysts.

Optimization and Characterization of an Antioxidant Exopolysaccharide Produced by Cupriavidus pauculus 1490

Xia Mingchen,Zhang Shishi,Shen Li,Yu Runlan,Liu Yuandong,Li Jiaokun,Wu Xueling,Chen Miao,Qiu Guanzhou,Zeng Weimin

In the present study, exopolysaccharides (EPS) production by Cupriavidus pauculus 1490 was optimized by response surface methodology. The results showed that sodium gluconate (4.15 g/L), NH 4 Cl (0.52 g/L), and Na 2 HPO 4 ·12H 2 O (0.04 g/L) were the optimal medium components and concentrations. The actual EPS yield of 293.2 m g/L in the optimized medium was in close agreement with the predicted value of 283.35 m g/L. Analysis of fourier transform infrared spectroscopy indicated the EPS contained abundant functional groups, such as –OH, C=O and C–O–C, and all of them were attributed to the characteristics of polysaccharides. Mannose, glucuronic acid, glucose and xylose were detected as the main monosaccharide composition of EPS. Rheological analysis suggested that the rheogram of EPS has similar trend with Xanthan and presented the property of non-Newtonian fluid. Moreover, the addition of NaCl and KCl would partly weaken the shear stress of EPS. Three in vitro assays were conducted to evaluate the antioxidant potential of the EPS. Results demonstrated that the EPS possessed scavenging capacity on hydroxyl radical, DPPH radical and superoxide anion radical in a dose-dependent way. As indicated by above results, the EPS isolated from C. pauculus 1490 might serve as a potential antioxidant agent to be applied in nutraceutical and pharmaceutical industries.

Preparation and characterization of an effective microwave absorbent: RGO-MoS2-Fe3O4 nanocomposite

Ding Xiao,Fan Guang,Huang Yi,Wang Jianguo

Reduced graphene oxide-molybdenum disulfide (RGO-MoS 2 ) loaded Fe 3 O 4 nanoparticles composite (RGO-MoS 2 -Fe 3 O 4 ) is prepared via two-step hydrothermal reaction. RGO-MoS 2 possesses three dimension architecture structures. This structure can prevent RGO and MoS 2 nanosheets restacked together and provide substrates for the Fe 3 O 4 nanoparticle decoration. The sizes of Fe 3 O 4 are in the range of 5–20 nm. As a microwave absorbent: the minimum reflection loss (R L ) value is -47.67 dB at 17.44 GHz when the thickness is only 1.5 mm. The absorption bandwidth (R L  < −10 dB) can reach 4.72 GHz with the thickness is 1.7 mm. Compared with the previously reported literature, RGO-MoS 2 -Fe 3 O 4 nanocomposite exhibits excellent microwave absorption performance and can be served as an light-weight microwave absorber.