CELLULOSE
·
2018
·Vol. 25
·期 10
·5659-5668
·
IF 3.809
Wang Guozhen,Meng Yan,Zhou Jinping,Zhang Lina
Abstract
Herein, one-step conversion of cellulose dissolved in 1.75 mol L −1 NaOH/0.074 mol L −1 ZnO aqueous solution to organic acids was realized through a hydrothermal degradation without heterogeneous catalyst. The effects of solvent, the concentrations of NaOH and ZnO, O 2 pressure, temperature and the reaction time on the yield of organic acids were investigated and discussed. The components of the degraded products were characterized with total organic carbon and high performance liquid chromatography. The results indicated that cellulose was depolymerized successfully to organic acids. Formic acid as the predominant species with 80.0% yield was obtained at the optimal conditions (150°C, 2 h, 3.0 MPa O 2 ), which was much higher than those reported in literatures. The small amount of ZnO in the solvent played an important role not only to promote the cellulose dissolution, but also to accelerate its oxidative degradation. The main features of this one-step degradation of cellulose were the green solvent, pre-dissolution of catalyst, and high selectivity. This work opened up a new avenue for the conversion of cellulose to organic acids under mild conditions. Graphical abstract The oxidative degradation of cellulose dissolved in NaOH/ZnO aqueous solution into organic acids was conducted under pressed O 2 without heterogeneous catalyst. The yield of FA which was the main product reached up to 80.0%.
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Nature Communications
·
2018
·Vol. 9
·期 1
·1-8
·
IF 12.353
Zhang Ting,Liu Gang-Qin,Leong Weng-Hang,Liu Chu-Feng,Kwok Man-Hin,Ngai To,Liu Ren-Bao,Li Quan
Diamond nitrogen-vacancy (NV) center-based magnetometry provides a unique opportunity for quantum bio-sensing. However, NV centers are not sensitive to parameters such as temperature and pressure, and immune to many biochemical parameters such as pH and non-magnetic biomolecules. Here, we propose a scheme that can potentially enable the measurement of various biochemical parameters using diamond quantum sensing, by employing stimulus-responsive hydrogels as a spacing transducer in-between a nanodiamond (ND, with NV centers) and magnetic nanoparticles (MNPs). The volume phase transition of hydrogel upon stimulation leads to sharp variation in the separation distance between the MNPs and the ND. This in turn changes the magnetic field that the NV centers can detect sensitively. We construct a temperature sensor under this hybrid scheme and show the proof-of-the-principle demonstration of reversible temperature sensing. Applications in the detection of other bio-relevant parameters are envisioned if appropriate types of hydrogels can be engineered.
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JOURNAL OF MATERIALS SCIENCE
·
2018
·Vol. 53
·期 23
·15895-15906
·
IF 2.993
Sun Li,Lv Pengcheng,Li Haonan,Wang Fa,Su Wenxian,Zhang Lixin
Abstract The green and controllable synthesis of Au–Ag alloy nanoparticles (NPs) in one-pot has been a challenge in nanotechnology. Here, the soluble starch was employed as a reducing and capping agent to synthesize stable Au–Ag alloy NPs without using any toxic agent. The surface plasmon resonance wavelength and the composition of Au–Ag alloy NPs could be continuously adjusted only by the synthesis time in one-pot. Au–Ag alloy NPs were characterized by means of various techniques. It could be found as-prepared NPs were quasi-spherical with a small average size and a face-centered cubic polycrystalline structure. The above green synthesis method, facile, efficient and eco-friendly, can be extended to the controllable synthesis of other bimetallic NPs. Obtained Au–Ag alloy NPs exhibited a superior photocatalytic activity and stability for the 4-nitrophenol (4-NP) degradation due to abundance hydroxyl groups of the soluble starch and the synergistic effect between Au and Ag elements. The rate constant of 4-NP degradation could be linearly tuned by the composition of Au–Ag alloy NPs and their synthesis time besides their addition amount. The above methods to control the rate constant provide promising routes for other photocatalytic reactions using bimetallic NPs as photocatalysts. Graphical Abstract
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MICROCHIMICA ACTA
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2018
·Vol. 186
·期 1
·1-7
·
IF 5.705
Lu Xuewen,mei Ting,Guo Qi,Zhou Wenjing,Li Xiaomei,Chen Jitao,Zhou Xinke,Sun Ning,Fang Zhiyuan
The sensitivity of lateral flow assays (LFA) was increased 30-fold by making use of spherical core-shell gold-silica nanoparticles (AuNP@SiO 2 NPs). They can be prepared by silylation of surfactant stabilized AuNPs. The AuNP@SiO 2 NPs are highly stable and can be used to label antibodies at virtually any concentration. The detection limit of an LFA for alpha-fetoprotein (AFP) can be decreased from 10 ng·mL −1 to 300 pg·mL −1 which makes it comparable to an enzyme-linked immunosorbent assay. To demonstrate the applicability to an immunoassay, a sandwich assay was developed for vanillin by covalent modification of the AuNP@SiO 2 NPs with antibody. By using the method, vanillin can be detected visually in milk powder samples in concentrations as low as 100 ng·g −1 . With unique optical property and great stability, this AuNP@SiO 2 endows great potential in biosensing applications.
Controlled growth of AuNP@SiO 2 . The newly prepared AuNP has a negative hydration layer. This layer is further surrounded by a bilayer of CTAB through electrostatic attraction. The hydrophobic inner layer enables the access and assembling of APTES and MTTS. After the hydrolysis of siloxane, a thin layer of silica shell is formed around AuNP.
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Nanoscale Research Letters
·
2018
·Vol. 13
·期 1
·1-8
·
IF 3.125
Lu Junlin,Shang Chaoqun,Meng Qingguo,Lv Haiqin,Chen Zhihong,Liao Hua,Li Ming,Zhang Yongguang,Jin Mingliang,Yuan Mingzhe,Wang Xin,Zhou Guofu
A series of novel visible light driven all-solid-state Z-scheme BiOBr 0.3 I 0.7 /Ag/AgI photocatalysts were synthesized by facile in situ precipitation and photo-reduction methods. Under visible light irradiation, the BiOBr 0.3 I 0.7 /Ag/AgI samples exhibited enhanced photocatalytic activity compared to BiOBr 0.3 I 0.7 and AgI in the degradation of methyl orange (MO). The optimal ratio of added elemental Ag was 15%, which degraded 89% of MO within 20 min. The enhanced photocatalytic activity of BiOBr 0.3 I 0.7 /Ag/AgI can be ascribed to the efficient separation of photo-generated electron–hole pairs through a Z-scheme charge-carrier migration pathway, in which Ag nanoparticles act as electron mediators. The mechanism study indicated that ·O 2 − and h + are active radicals for photocatalytic degradation and that a small amount of ·OH also participates in the photocatalytic degradation process.
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IRANIAN POLYMER JOURNAL
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2018
·Vol. 27
·期 12
·951-963
·
IF 1.278
Gao Jiao,Luo Peng,Yan Xingyan,Hou Linxi
N -Isopropylacrylamide (NIPAM) was successfully grafted on reduced graphene oxide (RGO) by free radical polymerization and characterized by attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy, transmission electron microscope (TEM) measurements, thermogravimetric analysis and ultraviolet–visible transmission spectroscopy. The synthesized poly( N -isopropylacrylamide)–reduced graphene oxide (PNIPAM–RGO) was used to improve the properties of polysulfone (PSF) membranes with different PNIPAM–RGO weight fractions. The structure and properties of PNIPAM–RGO/PSF membrane were characterized by X-ray photoelectron spectroscopy, scanning electron microscopy, atomic force microscope, contact angle and tensile testing. The water permeability, self-cleaning recovery rate and water flux decline factor were tested. The blend membrane with 0.4 wt% PNIPAM–RGO possessed the optimal rejection and exhibited an impressive self-cleaning recovery rate and fracture strain of 98.6 and 72.2%, showing a 67.4 and 76.5% enhancement compared to that of pure PSF membrane (58.9 and 40.9%), respectively. Meanwhile, the water flux decline factor decreased from 21.0 to 7.8%. The drastic change of permeability to aqueous solution, observed around lower critical solution temperature of PNIPAM–RGO, proved the thermal sensitivity of the blend membrane. The NIPAM grafted onto RGO by free radical polymerization and utilizing the advantages of both PNIPAM and RGO, which was used as an additive in the membrane, and very hard to lose during the membrane formation and application. The resulting membrane exhibited a significant increase in self-cleaning recovery rate, hydrophilicity, mechanical strength and thermosensitivity.
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JOURNAL OF SOL-GEL SCIENCE AND TECHNOLOGY
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2018
·Vol. 89
·期 2
·448-457
·
IF 1.745
Zhang Wei,Li Zhi,Shi Long,Li Zhicheng,Luo Yan,Liu Qiong,Huang Rui
Abstract To reduce the flammability, hydrophobic silica aerogels (SAs) were modified by replacing commonly used trimethylchlorosilane (TMCS) with methyltrichlorosilane (MTCS). It was observed that the MTCS modified SAs (MSA) showed similar physicochemical properties to those TMCS modified SAs (TSA), including the density, thermal conductivity, hydrophobicity, and even thermal stability. However, the flammability of MSA was observed much lower than that of TSA, which was reflected by the significantly decreased gross calorific value (GCV). Furthermore, it was known from the kinetic and thermodynamic analyses that the pyrolysis of MSA became more difficult with the increasing conversion rate ( α ), which was evidenced by the fact that the apparent activation energy ( E ) kept rising to about 194 kJ/mol during the whole pyrolysis. Based on the changed E along the time, the pyrolysis process could be divided into two stages, in which α = 0.4 was considered as the turning point. Those main thermodynamic parameters, including pre-exponential factor ( A ) and the changes of enthalpy (Δ H ) and entropy (Δ S ), showed a quite consistent tendency with the E , whereas the change of Gibbs free energy (Δ G ) almost kept unchanged. The research outcome of this study can provide a deep understanding of the pyrolysis process of SAs and render the public realize the thermal hazard risk of SAs.
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Bio-Design and Manufacturing
·
2018
·Vol. 1
·期 4
·254-264
·
IF 0
Song Juqing,Zhu Guanglin,Gao Huichang,Wang Lin,Li Nanying,Shi Xuetao,Wang Yingjun
Inspired by the constitution of things in the natural world, three-dimensional (3D) nanofiber scaffold/cells complex was constructed via the combination of electrospinning technology and origami techniques. The nanofiber boxes prepared by origami provided a limited space for the layer-by-layer nanofiber films, and the human fetal osteoblasts (hFOBs) seeded on the both sides of the nanofiber films were expected to facilitate the bonding of the adjacent nanofiber films through the secretion of extracellular matrix. Specifically, the hFOBs presented 3D distribution in the nanofiber scaffold, and they can stretch across the gaps between the adjacent nanofiber films, forming the cell layers and filling the whole 3D nanofiber scaffold. Eventually, a 3D block composed of electrospun nanofiber scaffold and cells was obtained, which possesses potential applications in bone tissue engineering. Interestingly, we also created 3D nanofiber structures that range from simple forms to intricate architectures via origami, indicating that the combination of electrospinning technology and origami techniques is a feasible method for the 3D construction of tissue engineering scaffolds.
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Food Analytical Methods
·
2018
·Vol. 12
·期 3
·697-704
·
IF 2.245
Cui Beijiao,Liu Haiyan,Yu Huan,Pang Xiaoya,Yan Hongyuan,Bai Ligai
In this paper, a hybrid monolithic column with modified nanodiamond and 1-dodecene as co-monomers was prepared and applied to the online enrichment and purification of β-sitosterol in edible oil. The obtained monolithic column was characterized by scanning electron microscopy (SEM) and nitrogen adsorption–desorption isotherm measurement, which indicated that the monolith possessed characteristics of porous structure and high permeability. Under the optimum conditions for extraction and determination, the linear regression coefficient for β-sitosterol was 0.998; the limit of detection (LOD) and the limit of quantitation (LOQ) were 3.0 μg mL −1 and 10.0 μg mL −1 , respectively; the relative standard deviation (RSD) of intra-day and inter-day assays for four edible oils were 2.33–6.58% and 3.24–6.94%, respectively. The recovery was in the range of 89.6–105.5%. The results showed that the hybrid monolithic column with high selectivity and good permeability were successfully used as online solid-phase extraction (SPE) column for determination of β-sitosterol in edible oil.
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Frontiers of Chemical Science and Engineering
·
2018
·Vol. 12
·期 3
·457-466
·
IF 2.643
Shang Jiaojiao,Yao Guo,Guo Ronghui,Zheng Wei,Gu Long,Lan Jianwu
Biodegradable poly(ether-imide-ester) elastomers were synthesized from succinic acid, 1,4-butanediol, polyethylene glycol 1000 and N ′, N -bis(2-carboxyethyl)- pyromellitimide which was derived from pyromellitic dianhydride and glycine. The chemical structures, crystallinities, thermal stabilities, mechanical properties, hydrophilicities and biodegradabilities of these elastomers were investigated. The hard segments of the linear aliphatic poly (ether-ester) exhibited monoclinic chain packing. Increasing the amount of aromatic bisimide moieties in the poly (ether-ester) reduced the crystallinity of the material and improved the thermal stability and tensile strength of the elastomers. In addition, introducing a suitable amount of aromatic bisimide moieties into the poly(ether-ester) backbones endowed the elastomers with improved biodegradability but too many aromatic bisimide groups reduced the biodegradability of the elastomers.
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JOURNAL OF MATERIALS SCIENCE-MATERIALS IN ELECTRONICS
·
2018
·Vol. 29
·期 19
·16799-16804
·
IF 2.324
Peng Xiaohan,Liu Xiaolin,Qu Peng,Yang Bing
Boron nitride nanosheets (BN NSs) with about 2 nm thickness and 200–400 nm lateral sizes were prepared by ultrasonically exfoliating bulk boron nitride (BN) powders in deionized water (DI). BN NSs/polyvinylidene fluoride (PVDF) composites were fabricated by a solution casting method. The enhanced breakdown strength and energy density of the composites were obtained at a low BN NSs weight fraction. The maximum breakdown strength and discharged energy density of 8 wt% BN NSs/PVDF composites reached to 486 kV/mm and 7.25 J/cm 3 , respectively, which led to 54 and 99% increase compared with pure PVDF (306 kV/mm, 3.63 J/cm 3 ). Meanwhile, the loss tangent of BN NSs/PVDF composites was lower than pure PVDF. The enhanced dielectric properties could be attributed to BN NSs with high insulation and wide band gap. In addition, two-dimensional (2D) BN NSs fillers tended to be perpendicular to the applied electric field and effectively acted as insulating barriers to improve the breakdown strength and energy density.
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ANALYTICAL AND BIOANALYTICAL CHEMISTRY
·
2018
·Vol. 410
·期 18
·4285-4291
·
IF 3.307
Liu Dongkui,Lu Xing,Yang Yiwen,Zhai Yunyun,Zhang Jian,Li Lei
Acute myocardial infarction (AMI) is one of the leading risks to global health. Thus, the rapid, accurate early diagnosis of AMI is highly critical. Human cardiac troponin I (cTnI) has been regarded as a golden biomarker for AMI due to its excellent selectivity. In this work, a novel fluorescent aptasensor based on a graphene oxide (GO) platform was developed for the highly sensitive and selective detection of cTnI. GO binds to the fluorescent anti-cTnI aptamer and quenches its fluorescence. In the presence of cTnI, the fluorescent anti-cTnI aptamer leaves the surface of GO, combines with cTnI because of the powerful affinity of the fluorescent anti-cTnI aptamer and cTnI, and then restores the fluorescence of the fluorescent anti-cTnI aptamer. Fluorescence-enhanced detection is highly sensitive and selective to cTnI. The method exhibited good analytical performance with a reasonable dynamic linearity at the concentration range of 0.10–6.0 ng/mL and a low detection limit of 0.07 ng/mL ( S / N = 3). The fluorescent aptasensor also exhibited high selectivity toward cTnI compared with other interference proteins. The proposed method may be a potentially useful tool for cTnI determination in human serum.
A novel fluorescent aptasensor for the highly sensitive and selective detection of cardiac troponin I based on a graphene oxide platform.
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