Easy-operated Method Research Articles

Fumed silica additives enables tunable wettability of the resin for improved composite bipolar plate

Composite bipolar plates (CBP) composed of resin and conductive filler are critical components in proton exchange membrane fuel cell (PEMFC) for achieving mechanical strength and electrical conductivity. The conductive filler entirely enveloped by resin is of significance for the flexibility of the CBP; while connected resin blocks the continued conductive channels and thus weakens the electrical properties of CBP. Herein, we propose a trade-off method between flexibility and conductivity of the CBP by wettability regulations of the resin, in which fumed silica additives are introduced into epoxy as composite adhesives. The abundant hydrogen bonds are demonstrated to be well-formed between epoxy and fumed silica for decreasing surface free energy (SFE) between resin and graphite. As a result, the composite adhesive with 2 % fumed silica delivers moderate wettability enabling much improved CBP, which exhibits high electrical conductivity of 233.33 S cm−1 as well as flexural strength of 66.4 MPa. Moreover, the CBP also delivers improved areal specific resistance (5.34 mΩ cm2), thermal conductivity (10.58 W (m K)−1), and corrosion behaviors (0.0701 A cm−2) which guarantee the operation of the PEMFC. This work provides new insight from the wettability regulation of resins for improved CBP, which is an easy-operating method and has great potential for application in practical CBP fabrication.

Preparation and electromagnetic wave absorption of compressible graphene aerogels

In this study, a developed easy-operation method was adopted to generate ultralight and compressible graphene aerogels by using graphene oxide and ammonia. By changing the process parameters, such as reduction temperature, reducing agent content and ammonia concentration, the variation laws of the density and pore size of aerogels were obtained, which aided in realizing the controllable preparation of aerogel structures. The prepared graphene aerogel has good compressive performance, and its density can reach 5.26 mg/cm3. Although it was repeatedly compressed 200 times under a load that was 4000 times as large as its own weight, it maintained its structural integrity and mechanical properties. An ideal model of three-dimensional graphene aerogel was constructed, and the electromagnetic wave absorption performance was simulated using the Computer Simulation Technology (CST) Microwave Studio software. The results showed that when the thickness, pore size and height of the sheet were 1.4, 5 and 14 mm, respectively, an optimal electromagnetic wave absorption effect of −31.08 dB could be obtained. Furthermore, the effects of thickness, pore size and height of the sheet on the electromagnetic wave absorption performance are revealed, which provide a reference for the structural design of aerogels with both compressibility and electromagnetic wave absorption performance.

Structural rejuvenation and relaxation of a metallic glass under the periodically thermal-mechanical loading

The current work focuses on effect of the thermomechanical protocol which can lead either to aging or rejuvenation of glass through decoupling of the thermal and mechanical processes. We demonstrated that the La-based metallic glass shows a kind of material hypomnesia because a clearer rejuvenation trend is observed just after imposing strain oscillations of increasing amplitude than after a long period from that, as it is proved by the results of stress relaxation. There is a threshold value of the oscillation amplitude that separates the effect of the protocol between acceleration of aging and rejuvenation. The activated energy spectrums imply plasticity and mechanical heterogeneity of the metallic glass promoted by simple mechanical stimulation. Mechanical perturbations applied not long ago in time are vital for hypomnesia metallic glasses, in which different histories lead to various degrees of aging or rejuvenation. The correlation between the thermomechanical properties of metallic glasses and the previous application of strain oscillations of various amplitude is unveiled in this work, revealing an effective tool for regulating the structural state of metallic glasses through an easy-operated method.

A novel dynamic coating medium for single stranded DNA separation in capillary electrophoresis: Thermosensitive hydrogel nanoparticles

Nowadays, research on single-stranded DNA (ssDNA) requires a quick, effective and easy operation method to separate small ssDNA fragments from the organism and ssDNA production process to realize their application in gene therapy and drug diagnosis. Herein, a novel separation matrix of thermosensitive hydrogel nanoparticles (NPs) was proposed, which has been successfully applied to the isolation of biomacromolecules such as enzymes, peptides and proteins, based on the desirable properties of various monomers and advantages, such as high sieving capacity, tunability of hydrophilic and hydrophobic performance and non-toxicity. The flexible particles were prepared by precipitation polymerization method in aqueous solution while N-isopropylacrylamide (NIPAm), acrylic acid (AAc) and N-t-butyl acrylamide (TBAm) was performed as co-monomer, which were first used as the dynamic coating to separate small fragments of ssDNA in capillary electrophoresis (CE). The synthesized NPs were bound to the inner wall of the capillary through non-covalent interactions forming stable dynamic coating to affect the electroosmotic flow and improve the separation reproducibility of ssDNA fragments. Based on the formulation design of NPs and condition optimization of electrophoresis, the running buffer TG (25 mM Tris, 192 mM glycine, pH 8.3) was modified by 4 mg·mL−1 optimized NPs aqueous suspension addition while its molar feed ratio of NIPAm /AAc /TBAm /BIS was 83/5/10/2 and particle size was about 214 nm. Both the formulation design and temperature sensitivity of hydrogel nanoparticles contributed to the DNA separation efficiency. The designed NPs with low viscosity provide an approach to increase their capability as the separation medium for small fragment DNA with important physiological functions great potential and promise.

Improvement of electrochemical properties of lithium iron phosphate cathode by rare earth oxides modification

LiFePO4 cathode material has sluggish Li-ion diffusivity, which largely depends on surface modification to accelerate its slow kinetic process. Metal oxides, such as Al2O3, are promising coating materials to improve the capacity retention of the cathode materials in lithium-ion batteries, but their improvement on the diffusion rate of Li-ion is limited. In order to obtain the lithium iron phosphate cathode material with excellent rate and cyclic stability, this paper uses the advantages of La2O3 which has both good stability and low lithium ion diffusion barrier to prepare LiFePO4/C@La2O3 by a simple and easy operation method. The cathode of LiFePO4/C@La2O3 shows high lithium ion diffusivity of 1.4982 × 10−13 and decreased interface impedance by calculating the Li+ diffusion coefficient and measuring conductivity. Furthermore, the LiFePO4/C@La2O3 exhibits excellent rate capacibility (126 mAh g−1 at 10 C within 2.4–4.2 V) and long-cycle stability (96.5% capacity retention at 1 C after 500 cycles). These results indicate that further research on these oxide coating materials can enlarge the applicability of these materials.

Stimulating fungal cell wall integrity by exogenous β-glucanase to improve the production of fungal natural products.

The low production of natural products (NPs) is still the critical restrictive factor in exploiting their potential large-scale applications and a barrier to isolating and identifying other meaningful products. Given that the stimulation of cell wall integrity (CWI) has become a novel strategy to modulate the production of microbial natural products, herein, exogenous β-glucanase treatment was developed as an external cell wall β-glucan stress to stimulate the fungal CWI, and then to improve the production of fungal NPs. It was found that the production of fungal NPs cercosporin and sophorolipids, biosynthesized by Cercospora sp. and Starmerella bombicola, respectively, was significantly improved by the treatment of β-glucanase under a controllable dose. Moreover, it demonstrated that β-glucanase had an ability to stimulate fungal CWI through slight fungal superficial damage, thus facilitating the secretion of NPs. We expected that this easy-operating method to stimulate fungal CWI could be feasible to improve more fungal NPs production. KEY POINTS: • Exogenous β-glucanase stimulated the fungal cell wall integrity • Changing fungal cell walls modulated natural product production • β-glucanase with potential universal effects on more fungal natural products.

A UV cross-linked gel polymer electrolyte enabling high-rate and high voltage window for quasi-solid-state supercapacitors

Serving as a promising alternative to liquid electrolyte in the application of portable and wearable devices, gel polymer electrolytes (GPEs) are expected to obtain more preferable properties rather than just be satisfied with the merits of high safety and deformability. Here, an easy-operated method is employed to fabricate cross-linked composite polymer membranes used for GPEs assisted by UV irradiation, in which N-doped carbon quantum dots (N-CQDs) and TiO2 are introduced as photocatalysts and additives to improve the performances of GPEs. Specifically, N-CQDs participate as a cross-linker to construct the inner porous structure, and TiO2 nanoparticles serve as a stabilizer to improve the electrochemical stability of GPEs under high voltage (3.5 V). The excellent thermal and mechanical stability of the membrane fabricated in this work guarantee the safety of the supercapacitors (SCs). This GPE based SC not only exhibits prominent rate performance (105% capacitance retention at the current density of 40 A g−1) and cyclic stability (85% at 1 A g−1 under 3.5 V after 20,000 cycles), but also displays remarkable energy density (42.88 Wh kg−1) with high power density (19.3 kW kg−1). Moreover, the superior rate and cycling performances of the as-prepared GPE based flexible SCs under flat and bending state confirm the feasibility of its application in flexible energy storage devices.

Development of a specific monoclonal antibody-based icELISA for detection of arecoline in traditional Chinese medicines and fresh areca nuts

ABSTRACT Arecoline, the dominant alkaloid existing in areca nuts, is an addictive substance and classified as a Group 2B potential human carcinogen. Currently, the detection of arecoline is mostly dependent on chromatography-based approaches, which are time-consuming and expensive. We used arecaidine as a hapten to produce a highly specific monoclonal antibody (mAb) against arecoline. An indirect competitive enzyme-linked immunosorbent assay (icELISA) was developed using the mAb-A5H12, to detect arecoline in traditional Chinese medicines and fresh areca nuts. The icELISA indicated that the half maximum inhibition concentration (IC50) for arecoline was 67.9 ng/mL, with a working range of 10.1–502.6 ng/mL and a limit of detection (LOD) of 3.6 ng/mL. High-performance liquid chromatographic (HPLC) confirmed the accuracy and the working range of icELISA, suggesting that the icELISA approach based on the arecoline specific antibody could be a widely applicable and easy operation method in detection of arecoline in foods and medicines.

Pseudo-three component reaction of indole with benzaldehyde derivatives for the preparation of bis(indolyl)methanes in the presence of nano-CuO-CeO2

In this research study, a nano-CuO-CeO2 catalyzed environmentally benign strategy for the preparation of bis(indolyl)methane derivatives via the three-component reaction between indoles and aldehyde in aqueous media under reflux conditions in excellent yields was established. The structure of the prepared compounds was confirmed using IR, 1H-NMR. The elemental analysis and morphology of the catalyst was characterized using transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The results revealed that this synthetic reaction is very simple and bis(indolyl)methane derivatives produced with good yields compared to other articles. The advantages of this method include catalyst recovery, high efficiency, and easy operation method. The highest efficiency (96%) in a short time (15 min) was obtained, which is very important compared to other previous methods presented.

Application of nano-CeO2 catalyst as a suitable and useful catalyst in the synthesis of 1,8-dioxooctahydroxanthenes

Xanthene and their derivatives are an important class of broad-spectrum heterocyclic compounds used as fluorescent dyes to visualize biomolecules and lasers. They have been reported to be antiviral for photodynamic treatment, bactericidal activity in agriculture. In this research, a simple method for the synthesis of high-efficiency 1,8-dioxooctahydroxanthenes through the reaction from aromatic aldehyde and dimedon derivatives in the presence of nano-CeO2 catalyst in water under the reflux conditions. The results revealed that this synthetic reaction is very simple and 1,8-dioxooctahydroxanthene derivatives produced with good yields compared to other articles. The advantages of this method include catalyst recovery, high efficiency and easy operation method. As shown in Table 5, the highest efficiency (95%) in a short time (1 h) was obtained in this study, which is very important compared to other previous methods presented.

Rapid Detection of Clostridium botulinum in Food Using Loop-Mediated Isothermal Amplification (LAMP).

Botulinum neurotoxins are considered as one of the most potent toxins and are produced by Clostridium botulinum. It is crucial to have a rapid and sensitive method to detect the bacterium Clostridium botulinum in food. In this study, a rapid detection assay of C. botulinum in food using loop-mediated isothermal amplification (LAMP) technology was developed. The optimal primers were identified among three sets of primers designed specifically based on the partial ntnh gene encoding nontoxic-nonhaemagglutinin (NTNH) for rapid detection of the target DNA in plasmids. The optimal temperature and reaction time of the LAMP assay were determined to be 64 °C and 60 min, respectively. The chemical kit could be assembled based on these optimized reaction conditions for quick, initial high-throughput screening of C. botulinum in food samples. The established LAMP assay showed high specificity and sensitivity in detecting the target DNA with a limit of 0.0001 pg/ul (i.e., ten times more sensitive than that of the PCR method) and an accuracy rate of 100%. This study demonstrated a potentially rapid, cost-effective, and easy-operating method to detect C. botulinum in food and clinical samples based on LAMP technology.

Acupoint-brain (acubrain) mapping: Common and distinct cortical language regions activated by focused ultrasound stimulation on two language-relevant acupoints

Acupuncture, taking the advantage of modality-specific neural pathways, has shown promising results in the treatment of brain disorders that affect different modalities such as pain and vision. However, the precise underlying mechanisms of within-modality neuromodulation of acupoints on human high-order cognition remain largely unknown. In the present study, we used a non-invasive and easy-operating method, focused ultrasound, to stimulate two language-relevant acupoints, namely GB39 (Xuanzhong) and SJ8 (Sanyangluo), of thirty healthy adults. The effect of focused ultrasound stimulation (FUS) on brain activation was examined by functional magnetic resonance imaging (fMRI). We found that stimulating GB39 and SJ8 by FUS evoked overlapping but distinct brain activation patterns. Our findings provide a major step toward within-modality (in this case, language) acupoint-brain (acubrain) mapping and shed light on to the potential use of FUS as a personalized treatment option for brain disorders that affect high-level cognitive functions.

One-step fabrication of the wear-resistant superhydrophobic structure on SiCp/Al composite surface by WEDM

Fabricating superhydrophobic structure on metal matrix can significantly improve its usability, such as anti-corrosion, self-cleaning, anti-icing, fluid drag reduction. However, the mechanical strength and wear resistance of the micro-nano structures on the common material (such as plastic/copper/aluminum/stainless steel) are not satisfactory. This paper aims to propose a high-efficiency and easy-operating method for fabricating wear-resistant superhydrophobic structure. Particle reinforced metal matrix composite (SiCp/Al) is chosen as workpiece material which has high specific strength, good wear resistance and low thermal expansion coefficient. A method of one-step fabricating multi-stage micro-nano structures for superhydrophobic structure on SiCp/Al composite surface using wire electrical discharge machining (WEDM) is presented. The primary structure and secondary structure are respectively semicircular groove texture and the surface microstructure from discharge machining. A set of cutting experiments are conducted to analyze the effect of the size of semicircular groove texture on the contact angle (CA) of workpiece surface. The multi-stage micro-nano structures on SiCp/Al composite surface is characterized by optical microscope, SEM, EDS. The experimental data shows that the maximum CA reaches 153.3° when the radius and center distance of semicircular groove texture are 400 μm and 700 μm, respectively. In addition, the superhydrophobic structure on SiCp/Al composite surface by WEDM exhibits excellent wear resistance. Eventually, the theoretical model of CA and the design criterion of semicircular groove texture for superhydrophobic structure are established. Specifically, the superhydrophobic structure can be obtained if the fraction of the solid-liquid area of the total projected surface area is lower than 0.084.

Denitrification mechanism and artificial neural networks modeling for low-pollution water purification using a denitrification biological filter process

Low-pollution water treatment is an important process for improving surface water quality. In the present study, a denitrification biological filter (DNBF) was used to treat synthetic low-pollution water, representing the typical water present in a heavily polluted urban seasonal river. The feasibility of alkali treated corncob as a denitrification slow-release carbon source was investigated. Furthermore, the performance of DNBF with different media (ceramsite, quartz sand and polypropylene plastics) and operating conditions was studied. The DNBF denitrification mechanism was analyzed and an artificial neural network model was established to predict the water quality of DNBF treated low-pollution water effluent. Results showed that when the alkali treated corncob dosage was 20 g and hydraulic retention time (HRT) was 2 h, the denitrification efficiency of DNBF with ceramsite as the filter medium was highest (≥94.7% for nitrate nitrogen and ≥ 85.6% for total nitrogen), with the effluent total nitrogen concentration meeting Class IV of the Environmental Quality Standard for Surface Water (GB 3838-2002, China). The total nitrogen removal efficiency increased with increasing HRT (0.5–2.0 h) and alkali treated corncob dosage (0–20 g). The denitrification rates established for DNBF with different media were ranked in the following order: ceramsite medium DNBF > polypropylene plastic medium DNBF > quartz sand medium DNBF. The relative abundance of denitrifying bacteria was highest (10.07% for quartz sand medium DNBF, 13.92% for polypropylene plastic medium DNBF and 23.13% for ceramsite medium DNBF) in the lower layer of the DNBFs, indicating that denitrifying bacteria are concentrated in the lower layer of the up-flow DNBF. Environmental factors (nitrite nitrogen, nitrate nitrogen, water temperature and pH) were found to affect the DNBF microbial community structure. The established artificial neural network model accurately predicted the effluent nitrogen concentration in DNBF treated low-pollution water. DNBF provides a feasible system for the treatment of heavily polluted urban seasonal rivers, achieving high total nitrogen removal efficiency using a low cost and easy operation method.

Rapid detection of sulfamethoxazole in plasma and food samples with in-syringe membrane SPE coupled with solid-phase fluorescence spectrometry

In this work, in-syringe membrane solid-phase extraction (MSPE) device was fabricated for the on-site sampling of sulfamethoxazole (SMX) in food samples followed by solid-phase fluorescence spectra analysis. The samples and fluorescamine (FA) were added to a syringe for derivation. Then, the derivative of SMX was extracted by a membrane in the syringe SPE device. Subsequently, the derivative on the membrane was measured immediately without additional elution procedure. The method was successfully applied in plasma, milk, and egg samples for the trace SMX detection, with the recovery of 98%–102%, RSDs from 1% to 6%. Compared with liquid chromatography, direct detection of the concentrated analyte significantly improved the sensitivity. Moreover, fluorescamine made it unnecessary to separate SMX from the interference. Consequently, it was a time-saving, low-cost, and easy-operation method, which demonstrated the potential of in-syringe SPE as a promising candidate for on-site analysis.

A carbon nanocoil-based flexible tip for a live cell study of mechanotransduction and electro-physiological characteristics.

The responses of living cells to external mechanical and electrical stimulation play important roles in regulating their biological functions and behaviors, and the response mechanisms have attracted great attention. Global stimulation on cells is generally used in traditional methods, but it is insufficient to investigate the mechanism of a dynamic physiological response at the subcellular level. At present, there is still lack of a low-cost and easy-operated method to apply local mechanical force and electrical stimulation on living cells. In this study, an individual carbon nanocoil (CNC) is used as a microscale noninvasive tool for local stimulation on a single cell, and a living cell imaging technology, fluorescence resonance energy transfer (FRET), is adopted to determine the responses of cells. After demonstrating that CNCs have low cytotoxicity to be applied in the biological field, an individual CNC is used as a needle tip to apply local mechanical force on a single osteosarcoma cell, which is transfected with a Src FRET biosensor to explore the mechano-physiological response. A spatially increasing and polarized Src protein activation is observed on the stimulated cell. Moreover, a single CNC is also used as an electrode to exert periodic local electrical stimulation. Osteosarcoma cells transfected with calcium-FRET biosensors show notable spatial-polarized FRET emission ratio distribution, and the FRET ratio shows a recoverable tendency towards the initial state after withdrawing the electrical stimulation. The cell biofunctions and structures are not damaged during the experiment process, which indicates that CNC is a kind of non-invasive and bio-safe tip. The CNC tip is a powerful tool for exploring the mechanotransduction and electro-physiological characteristics of living cells.

Mechanochemical Synthesis of Sulfonated Palygorskite Solid Acid Catalysts for Selective Catalytic Conversion of Xylose to Furfural

A green, safe, and easy-operation method for the preparation of sulfonated palygorskite solid acid catalyst (PAL-SO₃H) was developed by a mechanochemical process, where thiol groups (−SH) were grafted onto natural palygorskite by a high-speed shearing process with 3-mercaptopropyltrimethoxysilane in aqueous solution under mild conditions, followed by the oxidation of −SH to −SO₃H groups. The as-prepared PAL-SO₃H catalyst was applied in the catalytic conversion of biomass-derived xylose into furfural, and it showed excellent catalytic activity, and as high as 87% of furfural yield with 96% selectivity was achieved at 180 °C in 60 min reaction time in the γ-valerolactone–water mixture (95:5 v/v %). The PAL-SO₃H catalyst was tolerant of high initial xylose loading concentration up to 120 g/L and exhibited good recyclability. This study provides a green and mild process for the synthesis of a sulfonated solid acid catalyst, which should have potential applications in many fields such as catalysis and adsorption.

Buckling-controlled two-way shape memory effect in a ring-shaped bilayer

Shape memory polymers (SMPs) usually have a one-way shape memory effect. In this paper, an easy-operating method to realize a two-way shape memory effect was demonstrated in a ring-shaped bilayer structure where the two layers are SMPs with different thermal transition temperatures. By designing specific thermomechanical processes, the mismatched deformation between the two layers leads to a morphology change of ring-shaped bilayer structures from a smooth ring to a gear-like buckling shape under cooling and a reversible recovery to the smooth shape under heating. Such a morphology change is ascribed to occurrence and recovery of thermoelastic buckling. This method was validated by finite element simulation. We experimentally investigated the influence of pre-strain on buckling, and it was found that both the buckling occurrence and recovery temperature vary with pre-strain. Furthermore, considering a ring-shaped SMP–SMP bilayer structure, finite element analysis was conducted to study the influence of film thickness and modulus ratio of two layers on buckling behavior. The results showed that the critical buckling wavelength was greatly influenced by film thickness and modulus ratio. We made a theoretical analysis that accorded well with the numerical results.

Optimization of Ultrasound-Assisted Extraction of Total Flavonoids from Dendranthema indicum var. aromaticum by Response Surface Methodology.

Dendranthema indicum var. aromaticum is a new species with strong fragrance and is used as a herbal medicine by Chinese folks. The abundant flavonoids play important roles in its pharmacological activities. In this study, an ultrasound-assisted method was used to extract total flavonoids (TF) from D. indicum var. aromaticum by response surface methodology. A quadratic model was developed to optimize the extraction conditions, whose accuracy was verified by statistic analysis. Ethanol and acetic acid at the volume ratio of 70% : 2% were selected as the extract solvent. The optimized extraction conditions were as follows: extraction time, 40 min; solid/liquid ratio, 1 : 23 g/mL; and temperature, 60°C. This is the first report of an efficient and easy-operating method for TF extraction from D. indicum var. aromaticum. Besides, this study provides reference for future pharmacological research on D. indicum var. aromaticum and extraction of bioactive components from other herbs.

Composition- and size-engineering of porous PdAg alloy for high-performance ethanol electrooxidation

Control over the architecture, elemental distribution, composition and size of metal bimetallic nanocrystals can effectively manipulate and improve their catalytic performances. Herein, we construct the PdAg bimetallic nanostructures with Pd and Ag overlapped distribution to form an alloy feature via an easy operation method at ambient conditions. The prepared PdAg alloy nanocrystals are porous that composed of numerous branches on their surfaces with a composition of Pd100Ag0 to Pd61Ag39 and a size ranging from 16.4 ± 1.8 to 45.0 ± 1.5 nm. Impressively, after detail size- and composition-dependent electrocatalytic evaluations toward ethanol oxidation in alkaline, the Pd67Ag33 nanocrystals with a size of 27.0 ± 1.2 nm exhibit the highest mass activity (1394.49 mA mg−1), which is 4.77 and 5.46 times of porous Pd NCs and commercial Pd/C, respectively. Besides, the durability during electrocatalytic tests were also highly improved. The excellent electrocatalytic property is ascribed to the synergistic effect between Pd and Ag, the high surface area brought by the porous and branched morphology, as well as the proper size the alloy electrocatalysts provided.