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Hierarchical porous ZrO2/Al2O3 ceramics with controllable pore structure were fabricated by gel-foaming method using nontoxic sodium alginate as gelling agent. Both the rheological property of ceramic slurry and the curing mechanism of gelatin system were studied. The effects of ZrO2 content and sintering temperature on the pore structure and properties were also investigated. The three-dimensional net structure forms between calcium ion and sodium alginate molecule; then, the ceramic powder can realize in situ solidification. The porosity changes from 33 to 74% with different ZrO2 content and sintering temperature. The macropores can be controlled through adjusting the foaming agent and ZrO2 contents. The mesopores are mainly regulated by sintering temperature. The porosity and pore structure can be tailored through optimizing the gel-foaming and sintering process parameters. The sintering temperature has important influence on the mechanical properties. The porous ceramics with 25% ZrO2 content sintered at 1550°C shows the highest compressive strength of 130MPa. The mechanical properties are improved with the micro-crack toughening and phase transformation mechanisms of ZrO2 phases. Hierarchical porous ceramics with more inter-connective pores, high specific surface area, and suitable strength are promising for filtration and catalyst support applications. [ABSTRACT FROM AUTHOR]

Aluminum nitride ceramics were prepared by aqueous gelcasting method and pressureless sintering technique in N 2 atmosphere using Y 2 O 3 as sintering additives with nontoxic curdlan as gel system. The solidification mechanism of curdlan was studied. The effects of curdlan content and solid content on the microstructure, relative density and flexural strength of green bodies were investigated. The influences of Y 2 O 3 content and sintering soaking time on the microstructure and properties of sintered bodies were also studied. The results show that, as the temperature increases to 80 °C, the ceramic powders solidify through three-dimensional gel networks of curdlan during gelling process. The green bodies can be successfully fabricated through aqueous gelcasting method with modified powder as original materials. Suitable curdlan content and solid content contribute to fabricating green body with uniform microstructures and high flexural strength. The relative density and flexural strength of sintered bodies enhance as the Y 2 O 3 content and soaking time increase. The flexural strength and thermal conductivity are about 107.5∼172.3 MPa and 75.2∼112.5 W/(m·K), respectively. The sintered body with 4 wt% Y 2 O 3 soaking for 3 h exhibits the highest thermal conductivity because of appropriate relative density, uniform microstructure and reasonable intergranular phase distribution. The mechanical property and thermal conductivity of sintered bodies can be improved by optimizing the gelcasting process parameter, Y 2 O 3 content, and soaking time. The nontoxic gelling system will have wide application for aqueous gelcasting ceramic with complex shape. Aluminum nitride (AlN) ceramics were prepared by aqueous gelcasting and pressureless sintering technique using Y 2 O 3 as sintering additives with curdlan as gel system. 1.5 wt% curdlan and 50 vol% solid content are conductive to fabricating AlN green body with uniform microstructures. The relative density, grain size and microstructures relate to the properties of AlN ceramics. [Display omitted] • AlN ceramics can be prepared by aqueous gelcasting and pressureless sintering method with curdlan as gel system. • 50 vol% solid content and 1.5 wt% curdlan content are benefit to prepare AlN green body. • Y 2 O 3 sintering additive not only realizes liquid sintering but also effectively promotes properties of AlN ceramic. [ABSTRACT FROM AUTHOR]

Aberrant functioning of the proteasome has been associated with crucial pathologic conditions including neurodegeneration. Yet, the complex underlying causes at the cellular level remain unclear and there are conflicting reports of neuroprotective to neurodegenerative effects of proteasomal inhibitors such as lactacystin that are utilised as models for neurodegenerative diseases. The conflicting results may be associated with different dose regimes of lactacystin and hence we have performed a dose dependent study of the effects of lactacystin to identify concurrent changes in the cell membrane lipid profile and the dynamics of exocytosis using a combination of surface sensitive mass spectrometry and single cell amperometry. Significant changes of negatively charged lipids were associated with different lactacystin doses that showed a weak correlation with exocytosis while changes in PE and PE−O lipids showed dose dependent changes correlated with initial pore formation and total release of vesicle content respectively. [ABSTRACT FROM AUTHOR]

Aberrant functioning of the proteasome has been associated with crucial pathologic conditions including neurodegeneration. Yet, the complex underlying causes at the cellular level remain unclear and there are conflicting reports of neuroprotective to neurodegenerative effects of proteasomal inhibitors such as lactacystin that are utilised as models for neurodegenerative diseases. The conflicting results may be associated with different dose regimes of lactacystin and hence we have performed a dose dependent study of the effects of lactacystin to identify concurrent changes in the cell membrane lipid profile and the dynamics of exocytosis using a combination of surface sensitive mass spectrometry and single cell amperometry. Significant changes of negatively charged lipids were associated with different lactacystin doses that showed a weak correlation with exocytosis while changes in PE and PE−O lipids showed dose dependent changes correlated with initial pore formation and total release of vesicle content respectively. [ABSTRACT FROM AUTHOR]

We report the discovery that in the presence of chaotropic anions (SCN−) the opening of nanometer biological vesicles at an electrified interface often becomes a two‐step process (around 30 % doublet peaks). We have then used this to independently count molecules in each subvesicular compartment, the halo and protein dense‐core, and the fraction of catecholamine binding to the dense‐core is 68 %. Moreover, we differentiated two distinct populations of large dense‐core vesicles (LDCVs) and quantified their content, which might correspond to immature (43 %) and mature (30 %) LDCVs, to reveal differences in their biogenesis. We speculate this is caused by an increase in the electrostatic attraction between protonated catecholamine and the negatively charged dense‐core following adsorption of SCN−. [ABSTRACT FROM AUTHOR]

We report the discovery that in the presence of chaotropic anions (SCN−) the opening of nanometer biological vesicles at an electrified interface often becomes a two‐step process (around 30 % doublet peaks). We have then used this to independently count molecules in each subvesicular compartment, the halo and protein dense‐core, and the fraction of catecholamine binding to the dense‐core is 68 %. Moreover, we differentiated two distinct populations of large dense‐core vesicles (LDCVs) and quantified their content, which might correspond to immature (43 %) and mature (30 %) LDCVs, to reveal differences in their biogenesis. We speculate this is caused by an increase in the electrostatic attraction between protonated catecholamine and the negatively charged dense‐core following adsorption of SCN−. [ABSTRACT FROM AUTHOR]

The dopaminergic system has been suggested to serve as a functional target for ketamine, especially with its addictive and antidepressant effects. In this work, intracellular vesicle impact electrochemical cytometry and single cell amperometry were applied to a model cell line to show that the intravesicular contents and number of exocytotic events increased and the fraction of release decreased after treatment by subanesthetic ketamine (1 μM for 15 min). In addition, time‐of‐flight secondary ion mass spectrometry was used to show that cellular lipids change following acute ketamine administration relative to control cells with an increased proportion of low‐curvature lipids and a decreased proportion of high‐curvature lipids. We propose that ketamine modulates dopaminergic function with a dose‐dependent pharmacologic action by dominantly interacting with different proteins and changing lipid composition. It might be helpful to better understand the relationship of the dopaminergic system and drug abuse, as well as anesthetic and antidepressant effects. [ABSTRACT FROM AUTHOR]

Abstract A three-dimensional graphene/SiBCN hybrid composite was prepared by mixing and annealing Polyborosilazanes and sugar at 1200 °C. In this regard, the interface between the ceramic and the graphene formed a stable chemical bonding such as C-B-N, not physically absorbed as traditional meaning. Compared with the purity SiBCN ceramic, the hybrid material possessed a significant improvement on electromagnetic wave (EMW) absorption properties. When the thickness of the hybrid composites fixed on 2.5 mm, the maximum reflection coefficient (RC) increased from 1.36 to 24.24 dB and the bandwidth over 10 dB increased from 0 to 5.2 GHz. In addition, the bandwidth over 10 dB covered the whole X band when the thickness reached 3 mm. In short, this simple method was deemed to be a useful technology to fabricate a unique structure with excellent EMW absorption properties. [ABSTRACT FROM AUTHOR]

Nitrogen-doped nano TiO 2 powder was prepared using the solvothermal method. The nano TiO 2 powder was loaded on the porous ceramic carriers with a different aperture through the vacuum impregnation method using polyvinyl alcohol as a binder. The effects of deionized water content and carrier pore size on the microstructure and photocatalytic activity of nitrogen-doped nano TiO 2 powder and supported TiO 2 were investigated. The results show that, when introducing 25% deionized water, the nitrogen-doped nano TiO 2 powder obtains a good crystallinity, small grain size, and high photocatalytic properties because of adequate hydrolysis of tetrabutyl titanate. The photocatalytic activity of nitrogen-doped nano TiO 2 powder is improved by distorting the lattice and inhibiting grain growth. The nano TiO 2 powder can be tightly loaded on the surface of the strut or hole-wall of porous ceramic carriers. The absorption and photocatalytic activity of supported TiO 2 are demonstrably improved as the macropore provides the transmission channel, and the micropore realizes a good absorbing effect. The 20 PPI carrier with high porosity and suitable strength is beneficial to promote the photocatalytic property of supported TiO 2. Moreover, the supported TiO 2 is easily recycled and reused. Nano N-doped TiO 2 powder was loaded on the porous ceramic carriers using the polyvinyl alcohol as binder. Suitable deionized water content and porous ceramics aperture are conductive to fabricating supported TiO 2 with high photocatalytic activity under visible light. With the micro-grade holes of porous ceramics carriers increasing, the capacity, absorption effect and photocatalytic activity can be obviously improved. The supported TiO 2 is easily recycled and reused. [Display omitted] • Nano N-doped TiO 2 powder can be prepared with simple solvothermal method. • Nano N-doped TiO 2 powder was successfully loaded on the porous ceramic carriers with PVC as the binder. • The absorption effect and photocatalytic activity of supported TiO 2 can be improved. [ABSTRACT FROM AUTHOR]

Abstract: A nonintuitive observation of monovalent anion‐induced ion current rectification inversion at polyimidazolium brush (PimB)‐modified nanopipettes is presented. The rectification inversion degree is strongly dependent on the concentration and species of monovalent anions. For chaotropic anions (for example, ClO4−), the rectification inversion is easily observed at a low concentration (5 m m), while there is no rectification inversion observed for kosmotropic anions (Cl−) even at a high concentration (1  m). Moreover, at the specific concentration (for example, 10 m m), the variation of rectification ratio on the type of anions is ranged by Hofmeister series (Cl−≥NO3−>BF4−>ClO4−>PF6−>Tf2N−). Estimation of the electrokinetic charge density (σek) demonstrates that rectification inversion originates from the charge inversion owing to the over‐adsorption of chaotropic monovalent anion. To qualitatively understand this phenomenon, a concentration‐dependent adsorption mechanism is proposed. [ABSTRACT FROM AUTHOR]

Abstract: A nonintuitive observation of monovalent anion‐induced ion current rectification inversion at polyimidazolium brush (PimB)‐modified nanopipettes is presented. The rectification inversion degree is strongly dependent on the concentration and species of monovalent anions. For chaotropic anions (for example, ClO4−), the rectification inversion is easily observed at a low concentration (5 m m), while there is no rectification inversion observed for kosmotropic anions (Cl−) even at a high concentration (1  m). Moreover, at the specific concentration (for example, 10 m m), the variation of rectification ratio on the type of anions is ranged by Hofmeister series (Cl−≥NO3−>BF4−>ClO4−>PF6−>Tf2N−). Estimation of the electrokinetic charge density (σek) demonstrates that rectification inversion originates from the charge inversion owing to the over‐adsorption of chaotropic monovalent anion. To qualitatively understand this phenomenon, a concentration‐dependent adsorption mechanism is proposed. [ABSTRACT FROM AUTHOR]

Gelcasting method with nontoxic biopolymer as gel former can be used to prepare ceramics with complex shape. AlN ceramic bonded carbon (AlN/CBC) composites with light weight were fabricated by gelcasting and pressureless sintering method using nontoxic agarose as gel former with Y 2 O 3 + CaF 2 as sintering additive. The effect of sintering additive content and sintering temperature on the microstructure, flexural strength and thermal conductivity of composites was investigated. The results reveal that, as the temperature decreases, the raw powders solidify into three-dimensional net structures through abundant hydrogen bonds in the agarose. High sintering temperature facilitates densification and improves mechanical and thermal properties of the composites. Increasing sintering additive content can also tune the density and raise flexural strength. The AlN/CBC composite containing 7 wt% sintering additive content, which was sintered at 2000 °C, exhibits the highest thermal conductivity. Relative density, C content and microstructure uniformity have effects on properties of AlN/CBC composite. [ABSTRACT FROM AUTHOR]

Stationarity has traditionally been a requirement of geostatistical simulations. A common way to deal with non-stationarity is to divide the system into stationary sub-regions and subsequently merge the realizations for each region. Recently, the so-called partition approach that has the flexibility to model non-stationary systems directly was developed for multiple-point statistics simulation (MPS). The objective of this study is to apply the MPS partition method with conventional borehole logs and high-resolution airborne electromagnetic (AEM) data, for simulation of a real-world non-stationary geological system characterized by a network of connected buried valleys that incise deeply into layered Miocene sediments (case study in Denmark). The results show that, based on fragmented information of the formation boundaries, the MPS partition method is able to simulate a non-stationary system including valley structures embedded in a layered Miocene sequence in a single run. Besides, statistical information retrieved from the AEM data improved the simulation of the geology significantly, especially for the deep-seated buried valley sediments where borehole information is sparse. [ABSTRACT FROM AUTHOR]

Here we report for the first time that ion current rectification (ICR) can be observed at the micrometer scale in symmetric electrolyte solution with polyimidazolium brush (PimB)-modified micropipets, which we call micrometer-scale ion current rectification (MICR). To qualitatively understand MICR, a three-layer model including a charged layer, an electrical double layer, and a bulk layer is proposed, which could also be extended to understanding ICR at the nanoscale. Based on this model, we propose that when charges in the charged layer are comparable with those in the bulk layer, ICR would occur regardless of whether the electrical double layers are overlapped. Finite element simulations based on the solution of Poisson and Nernst-Planck equations and in situ confocal laser scanning microscopy results qualitatively validate the experimental observations and the proposed three-layer model. Moreover, possible factors influencing MICR, including the length of PimB, electrolyte concentration, and the radius of the pipet, are investigated and discussed. This study successfully extends ICR to the micrometer scale and thus opens a new door to the development of ICR-based devices by taking advantage of ease-in-manipulation and designable surface chemistry of micropipets. [ABSTRACT FROM AUTHOR]

The study of subcellular targets and biochemical processes within a living cell is valuable for biological and medical research. Secretory vesicles, one such important intracellular target, are nanoscale lipid structures that are capable of storage, transport, and secretion of, for example, neurotransmitters, hormones, proteins or waste products. Vesicles play an essential role in intercellular communication systems, as they facilitate the release of chemical messaging agents. If deregulated, these communication processes can be a central part in the pathogenesis of some neurodegenerative diseases or diabetes. Generally, due to their nanometer size and intracellular location, the analysis of single vesicles and their content is a great challenge. It requires sensitive techniques, micro/nanoscale tools and sensitive instruments with extreme spatio-temporal resolution. This review focuses on electrochemical sensors to study the biochemistry and quantification of messenger molecules and other species (e.g., reactive oxygen and nitrogen species) stored in organelles, providing new trends and developments in this field. Furthermore, we review the effect of the chemical environment of single cells (e.g., treatment with chemicals, drugs, lipids, and ions) on regulation of the physical and chemical properties of vesicles. Finally, unsolved challenges of and perspectives on vesicle electroanalysis are discussed. • Nano/micro sensors to measure the contents of organelles are reviewed. • Vesicle chemistry measured both ex situ and in situ in living cells. • Vesicle storage, transport, and secretion of (non) redox-active chemical messengers. • Vesicle cargo in neurodegenerative diseases, and diabetes. • Effects of the chemical environment on the properties of single vesicles. [ABSTRACT FROM AUTHOR]

Ion current rectification (ICR), which is the departure of the experimentally measured current-voltage curves from ohmic behavior, has recently drawn intensive interests from both a fundamental point of view and microfluidic-based applications. In this case, the rectification factor (RF), which is defined as the absolute value of the quotient between the currents recorded for one voltage polarity and the currents recorded for the same absolute value of voltage at the opposite polarity, is one of the most important parameters to describe the rectification behavior. Herein, we interestingly observed that RF is strongly dependent on the bias voltage from both the experimental and theoretically simulated results, and this dependence exhibits nonlinear deviation with increasing the rectification degree. At the same surface charge density, the linear deviation increases with decreasing the electrolyte concentration. When the electrolyte concentration remains the same, the linear deviation increases with increasing the surface charge density. The simulated results demonstrate that the electro-osmotic flow is not the dominating factor to this nonlinear phenomenon. This nonlinear deviation is considered to possibly originate from the inhomogeneous conductivity and the nonlinear change of conductance with the bias potential. This study is not only useful to understanding the ICR behavior at a conical glass nanopipette, but also potentially offers a new parameter to describe the rectification degree with this nonlinear relationship. [ABSTRACT FROM AUTHOR]

Spark plasma sintering (SPS) method was applied to prepare aluminum nitride/boron nitride (AlN-BN) composites using Sm 2 O 3 –CaF 2 as sintering additives. Effects of sintering additive and BN content on microstructure, thermal conductivity and dielectric properties of AlN-BN composites were investigated. The results reveal that dense AlN-BN composites with uniform microstructure can be successfully fabricated by SPS method. Suitable sintering additive not only promotes sintering densification process but also improves thermal and dielectric properties of AlN-BN composites through liquid phase sintering. AlN-BN composites containing 8 wt.% sintering additives exhibit higher thermal conductivity and lower dielectric loss. BN content, sintering additive, impurity elements, secondary phases, dislocation, and pores have influence on dielectric loss of AlN-BN composites. The main polarization mechanism of AlN-BN composites might be the space charge polarization. [ABSTRACT FROM AUTHOR]

The development of highly selective methodologies to enable in vivo recording of chemical signals is of great importance for studying brain functions and brain activity mapping. However, the complexity of cerebral systems presents a great challenge in the development of chem/(bio)sensors that are capable of directly and selectively recording bioactive molecules involved in brain functions. As one of the most important and popular interactions in nature, interionic interaction constitutes the chemical essence of high specificity in natural systems, which inspires us to develop highly selective chem/(bio)sensors for in vivo analysis by precisely engineering interionic interaction in the in vivo sensing system. In this tutorial review, we focus on the recent progress in the tuning of interionic interaction to improve the selectivity of biosensors for in vivo analysis. The type and property of the interionic interaction is first introduced and several strategies to improve the selectivity of the biosensors, including enzyme-based electrochemical biosensors, aptamer-based electrochemical biosensors, and the strategies to recruit recognition molecules are reviewed. We also present an overview of the potential applications of the biosensors for in vivo analysis and thereby for physiological investigations. Finally, we present the major challenges and opportunities regarding the high selectivity of in vivo analysis based on tuning interionic interaction. We believe that this tutorial review provides critical insights for highly selective in vivo analysis and offers new concepts and strategies to understand brain chemistry. [ABSTRACT FROM AUTHOR]

Aluminum nitride (AlN) ceramics were sintered with spark plasma sintering (SPS) technique using Y 2 O 3 (Sm 2 O 3 )–CaF 2 as the sintering additives. The purification effect of sintering additives, dielectric properties, microstructure and polarization mechanism of AlN ceramics were investigated. The densification process curves indicate that both sintering additive and special SPS sintering mechanism are conductive to reducing the sintering beginning temperature. The results of lattice parameters of AlN ceramics suggest that suitable sintering additives have prominent purification effect on the crystal lattice of AlN ceramics. Dielectric constant increases with Y 2 O 3 (Sm 2 O 3 ) content increasing, and the AlN ceramic containing 2 wt.% Sm 2 O 3 -1 wt.% CaF 2 exhibits the lowest dielectric loss. Oxygen impurities, dislocation and amorphous layer in the crystal structure of AlN ceramics increase dielectric loss of AlN ceramics. The space charge polarization caused by secondary phases and other defects might be the main polarization mechanism of AlN ceramics. [ABSTRACT FROM AUTHOR]

Development of new principles for fabrication of novel ionic devices has attracted much attention due to the potential applications of ionic devices in molecular computer, biosensing and electronic circuit. Inspired by optogenetics altering membrane voltage via light-controlled proteins, a new kind of light-controlled ionic switch was demonstrated here based on nanopipettes. Upon exposure to visible light, spiropyran (SP) does not coordinate with Zn2+, resulting in a relatively large ionic current. While, upon UV light irradiation, SP was transformed into merocyanine (MC) that coordinates with Zn2+ and thereby results in the decrease in the ionic current. The ionic current could be reversibly modulated by UV/Vis light irradiation. The finite-element simulation was performed to understand the possible mechanism underlying the light-controlled ionic switch based on nanopipettes. [ABSTRACT FROM AUTHOR]

We report the discovery that in the presence of chaotropic anions (SCN−) the opening of nanometer biological vesicles at an electrified interface often becomes a two‐step process (around 30 % doublet peaks). We have then used this to independently count molecules in each subvesicular compartment, the halo and protein dense‐core, and the fraction of catecholamine binding to the dense‐core is 68 %. Moreover, we differentiated two distinct populations of large dense‐core vesicles (LDCVs) and quantified their content, which might correspond to immature (43 %) and mature (30 %) LDCVs, to reveal differences in their biogenesis. We speculate this is caused by an increase in the electrostatic attraction between protonated catecholamine and the negatively charged dense‐core following adsorption of SCN−. [ABSTRACT FROM AUTHOR]

We have demonstrated a new strategy to improve the fluorescence detection limit by enhancing the energy transfer efficiency between carbon structures and fluorescent dyes using polyimidazolium-functionalized carbon nanostructures as a low background signal platform. Based on this, a highly sensitive method for thrombin was proposed with a detection limit as low as 2.79 pM without any amplification. [ABSTRACT FROM AUTHOR]

Abstract: Dense aluminum nitride (AlN) ceramics were prepared by Spark Plasma Sintering with rare-earth oxide and CaF2 as sintering additives. The effect of sintering additives on the density, phase composition, microstructure and thermal conductivity of AlN ceramics was investigated. The results showed that those sintering additives not only promoted densification through liquid-phase sintering but also improved thermal conductivity by decreasing oxygen impurities. Thermal conductivities of samples sintered with optimum proportion of rare-earth oxide and CaF2 were higher than those of other samples. During the Spark Plasma Sintering process, the microstructures, especially the content and distribution of secondary phases, played important roles on the thermal conductivity of AlN ceramics. [Copyright &y& Elsevier]

Abstract: Dense aluminum nitride (AlN) ceramics were prepared by Spark Plasma Sintering with rare-earth oxide and CaF2 as multiple components sintering additives. The effect of sintering additives on the density, phase composition, microstructure and thermal conductivity of AlN ceramics was investigated. The results showed that Spark Plasma Sintering could fabricate dense AlN ceramics with superior thermal properties in a very short time. The multiple components sintering additives not only promoted densification through liquid-phase sintering but also improved thermal conductivity by decreasing oxygen impurities. Thermal conductivity of samples sintered with 2wt.% Sm2O3–1wt.% CaF2 was higher than those of other samples. During the Spark Plasma Sintering process, the microstructures played a key role in controlling the thermal conductivity of AlN ceramics. [Copyright &y& Elsevier]

Abstract: Dense aluminum nitride ceramics were prepared by Spark Plasma Sintering with Sm2O3-CaF2 as multiple components sintering additives. The effect of sintering additives on the density, phase composition, microstructure and thermal conductivity of AlN ceramics was investigated. The results showed that Spark Plasma Sintering could fabricate dense AlN ceramics with superior thermal properties in a short time. The multiple components sintering additive not only purified the lattice of AlN ceramic by decreasing oxygen impurities but also reduced the content of grain boundaries by forming the evaporable second phases, thermal conductivity of AlN ceramics sintered with multiple components sintering additives was greatly improved. During the Spark Plasma Sintering process, the microstructures played a key role in controlling the thermal conductivity of AlN ceramics. [Copyright &y& Elsevier]

Abstract: Short-carbon-fiber-reinforced silicon carbide composites were prepared by hot-pressing with SiC powder, Polycarbosilane as precursor polymer and MgO–Al2O3–Y2O3 as sintering additives. The phase composition, microstructure and mechanical properties of the composites with different Polycarbosilane content were investigated. The results showed that, dense composites could be prepared at a relatively low temperature of 1800°C via the liquid-phase-sintering mechanism and the highest mechanical property was obtained for the composites with 20wt.% PCS and 8wt.% sintering additives. The amorphous interphase formed during sintering process in the composites not only contributed to the densification of the composites, but also improved the fiber–matrix bonding. The nano-silicon carbide derived from Polycarbosilane, could also play a role of improving the relative density of the composites. [Copyright &y& Elsevier]

Abstract: Dense aluminum nitride ceramics were prepared by Spark Plasma Sintering at a lower sintering temperature of 1700°C with Sm2O3 as sintering additives. The effect of Sm2O3 content on the density, phase composition, microstructure and thermal conductivity of AlN ceramics was investigated. The results showed that Spark Plasma Sintering could fabricate dense AlN ceramics with superior thermal properties in a very short time. Sm2O3 not only facilitated the densification via the liquid-phase sintering mechanism but also improved thermal conductivity by decreasing oxygen impurity. Thermal conductivity decreased with increasing amount of Sm2O3 and the highest thermal conductivity was obtained for the AlN ceramics with 2wt.% Sm2O3 content. During Spark Plasma Sintering process, only 2–3wt.% sintering additives was enough to fabricate dense AlN ceramics, and the microstructures played a key role in controlling the thermal conductivity of AlN ceramics. [Copyright &y& Elsevier]

Abstract: Microstructures of short-carbon-fiber-reinforced silicon carbide composites, prepared by hot-pressing with MgO–Al2O3–Y2O3 as sintering additives, were investigated by means of X-ray diffractometry, scanning electron microscopy, and transmission electron microscopy. The results showed that the composites could be densified at a relatively low temperature of 1800 °C via the liquid-phase-sintering mechanism. The amorphous interphase in the composites not only avoided the direct contact of the fibers with the matrix, but also improved the fiber/matrix bonding, so they could improve the densification of the composites and avoid the degeneration of the carbon fiber. The nano silicon carbide derived from polycarbosilane, could play a role of improving the relative density of the composites. [Copyright &y& Elsevier]

Abstract: A sensitive amperometric immunosensor for carcinoembryonic antigen (CEA) was prepared. Firstly, a porous nano-structure gold (NG) film was formed on glassy carbon electrode (GCE) by electrochemical reduction of HAuCl4 solution, then nano-Au/Chit composite was immobilized onto the electrode because of its excellent membrane-forming ability, and finally the anti-CEA was adsorbed onto the surface of the bilayer gold nanoparticles to construct an anti-CEA/nano-Au/Chit/NG/GCE immunosensor. The characteristics of the modified electrode at different stages of modification were studied by cyclic voltammetry (CV). The gold colloid, chitosan and nano-Au/Chit were characterized by transmission electron microscopy and UV–vis spectroscopy. In addition, the performances of the immunosensor were studied in detail. The resulting immunosensor offers a high-sensitivity (1310 nA/ng/ml) for the detection of CEA and has good correlation for detection of CEA in the range of 0.2 to 120.0 ng/ml with a detection limit of 0.06 ng/ml estimated at a signal-to-noise ratio of 3. The proposed method can detect the CEA through one-step immunoassay and would be valuable for clinical immunoassay. [Copyright &y& Elsevier]

Abstract: Short-carbon-fiber-reinforced SiC composites were prepared by precursor pyrolysis–hot pressing with MgO–Al2O3–Y2O3 as sintering additives. The effects of the amount of sintering additives on microstructure and mechanical properties of the composites were investigated. The results showed that the composites could be densified at a relatively low temperature of 1800°C via the liquid-phase sintering mechanism and the composite density and mechanical properties improved with the amount of additives. The amorphous interphase in the composites with more additive content, not only avoided the direct contact of the fibers with matrix, but also improved the fiber–matrix bonding. It proved that the fiber–matrix interphase characteristics played a key role in controlling mechanical properties of the composites. [Copyright &y& Elsevier]

Nanoplastics are recently recognized as neurotoxic factors for the nervous systems. However, whether and how they affect vesicle chemistry (i.e., vesicular catecholamine content and exocytosis) remains unclear. This study offers the first direct evidence for the nanoplastics‐induced neurotoxicity by single‐vesicle electrochemistry. We observe the cellular uptake of polystyrene (PS) nanoplastics into model neuronal cells and mouse primary neurons, leading to cell viability loss depending on nanoplastics exposure time and concentration. By using single‐vesicle electrochemistry, we find the reductions in the vesicular catecholamine content, the frequency of stimulated exocytotic spikes, the neurotransmitter release amount of single exocytotic event, and the membrane‐vesicle fusion pore opening‐closing speed. Mechanistic investigations suggest that PS nanoplastics can cause disruption of filamentous actin (F‐actin) assemblies at cytomembrane zones and change the kinetic patterns of vesicle exocytosis. Our finding shapes the first quantitative picture of neurotoxicity induced by high‐concentration nanoplastics exposure at a single‐cell level. [ABSTRACT FROM AUTHOR]

Nanoplastics are recently recognized as neurotoxic factors for the nervous systems. However, whether and how they affect vesicle chemistry (i.e., vesicular catecholamine content and exocytosis) remains unclear. This study offers the first direct evidence for the nanoplastics‐induced neurotoxicity by single‐vesicle electrochemistry. We observe the cellular uptake of polystyrene (PS) nanoplastics into model neuronal cells and mouse primary neurons, leading to cell viability loss depending on nanoplastics exposure time and concentration. By using single‐vesicle electrochemistry, we find the reductions in the vesicular catecholamine content, the frequency of stimulated exocytotic spikes, the neurotransmitter release amount of single exocytotic event, and the membrane‐vesicle fusion pore opening‐closing speed. Mechanistic investigations suggest that PS nanoplastics can cause disruption of filamentous actin (F‐actin) assemblies at cytomembrane zones and change the kinetic patterns of vesicle exocytosis. Our finding shapes the first quantitative picture of neurotoxicity induced by high‐concentration nanoplastics exposure at a single‐cell level. [ABSTRACT FROM AUTHOR]

A glassy carbon electrode was modified with gold nanoparticles (Au-NPs) on a quaternized cellulose support in a film composed of poly(ethylene glycol diglycidyl ether) (PEGDGE), and Hb was immobilized on the Au-NPs. The sensor film was characterized by UV-vis spectra, scanning electron microscopy, and electrochemical impedance spectroscopy. Cyclic voltammetry of the Hb in the Au@Qc/PEGDGE film revealed a pair of well-defined and quasi reversible peaks for the protein heme Fe(III)/Fe(II) redox couple at about −0.333 V (vs. SCE). The sensor film also exhibited good electrocatalytic activity for the reduction of nitric oxide and hydrogen peroxide. The amperometric response of the biosensor depends linearly on the concentration of nitric oxide in the 0.9 to 160 μM range, and the detection limit is as low as 12 nM (at 3σ). The response to hydrogen peroxide is linear in the 59 nM to 4.6 μM concentration range, and the detection limit is 16 nM (at 3σ). This biosensor is sensitive, reproducible, and long-term stable. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

This review describes recent advances in the use of carbon nanomaterials for electroanalytical detection of biogenic amines (BAs). It starts with a short introduction into carbon nanomaterials such as carbon nanotubes, graphene, nanodiamonds, carbon nanofibers, fullerenes, and their composites. Next, electrochemical sensing schemes are discussed for various BAs including dopamine, serotonin, epinephrine, norepinephrine, tyramine, histamine and putrescine. Examples are then given for methods for simultaneous detection of various BAs. Finally, we discuss the current and future challenges of carbon nanomaterial-based electrochemical sensors for BAs. The review contains 175 references. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Abstract: α-SiC/α-SiAlON composites with 80wt% α-SiC (6H phase) were fabricated by spark plasma sintering at 1800–2000°C in a 0.6atm nitrogen atmosphere. The effects of the temperatures on the phase development, microstructures and mechanical properties were investigated. The results showed the Si3N4, AlN, Al2O3, and Y2O3 particles were isolated by the 6H-SiC to prevent α-SiAlON formation at 1800°C. The Si3N4 decomposed at 1900°C and above, thus added Si in the phase compositions. The α-SiC grains grew anisotropic in the sintering liquids at 1800°C and 1900°C, forming the self-reinforcing microstructures, and accordingly increased the flexural strength and fracture toughness. In cooling down immediately after the temperature reached 2000°C, a transitory hold at 1700°C transformed the 6H-SiC into the 3C polytype in 30s. The electric current was suspected of activating this polytype transformation. [Copyright &y& Elsevier]

Abstract: A TaC composite with ∼11wt% in situ TaB2 was fabricated by spark plasma sintering at 1600–1900°C. The densification process was studied by analysis of the densifying shrinkage of the powder compacts. Three distinct stages for densification were determined. The starting powder mixture of TaC, B4C and Ta completed reaction to form the desired TaC and TaB2 at temperature <1583°C. At around ∼1750°C, the TaC/TaB2 material significantly improved relative density to ∼95% with rapid grain growth. The final densification took place very rapidly at 1900°C by releasing a high pressure vapor. [Copyright &y& Elsevier]

Hierarchically porous Al 2 O 3 ceramics with a porosity of 30–69% containing small intergranular pores and large pores created by a pore-forming agent were fabricated by gel-casting followed by partial sintering with starch addition. The influence of various pore types on the mechanical and thermal shock properties of the ceramics was subsequently investigated. A thermal shock parameter K was introduced to evaluate the dependence of strength degradation rate on the thermal shock temperature difference, and a new method for calculating the intergranular porosity and extrinsic porosity of the porous ceramics was developed. A low thermal shock strength degradation rate was obtained at a high ratio of fracture toughness (K IC) and elasticity modulus (E) of the material, which was achieved by decreasing the relative fraction of spheroidal extrinsic pores. However, the presence of these pores increased both the K IC and E values. [ABSTRACT FROM AUTHOR]

The differentiation of human induced pluripotent stem cells (hiPSCs) into functional dopaminergic neural precursors is the basis of cell therapy for Parkinson's disease (PD). However, the use of small molecule inhibitors/activators in the differentiation of hiPSCs in vitro leads to cell death and low differentiation efficiency. Moreover, the mechanism of differentiation remains unclear. MiR-210-5p was increased during hiPSCs differentiation. Whether it promotes hiPSCs differentiation and transplantation needs further study. Here, we overexpressed miR-210-5p in hiPSCs to study its roles and mechanisms. We found that miR-210-5p promoted the differentiation of hiPSCs into dopaminergic neural precursors and reduced the expression of SMAD4 and SUFU meanwhile. Luciferase assays showed that miR-210-5p binded to SMAD4 and SUFU , which are key molecules in the key signals (TGF-β and SHH) of hiPSCs differentiation. Furthermore, in the effect evaluation of cell transplantation into parkinsonian rats, the degree of behavioral recovery and the growth of transplanted cells in the group overexpressed miR-210-5p were similar to those in the positive group with all small molecule inhibitors/activators. Therefore, we conclude that miR-210-5p promotes the differentiation of hiPSCs into dopaminergic neural precursors by targeting SMAD4 and SUFU. In the therapeutic evaluation of cell transplantation, miR-210-5p can replace the use of corresponding small molecule inhibitors/activators to reduce cell death. This study provides an experimental basis and a new target for the miRNA-modified differentiation of hiPSCs and cell transplantation in clinical treatment of PD in the future. • MiR-210-5p is increased during hiPSCs differentiation into dopaminergic precursors. • MiR-210-5p promotes hiPSCs differentiation into midbrain dopaminergic precursors. • MiR-210-5p binds to SMAD4 and SUFU to inhibit TGF-β signal and activate SHH signal. • MiR-210-5p can replace the corresponding small molecule inhibitors/activators. • MiR-210-5p maybe a new target for hiPSCs differentiation and cell treatment of PD. [ABSTRACT FROM AUTHOR]

The very complex near-surface geology in Denmark is a big challenge when constructing 3D geological models. Borehole data alone are normally insufficient for proper 3D modelling because data are too widespread. Therefore, Airborne ElectroMagnetic (AEM) techniques are often used to obtain supplementary information on the spatial distribution and composition of the geology. A large-scale AEM survey and high-resolution seismic data along with both new and existing borehole data and seismic data from hydrocarbon exploration were available for the construction of a detailed 3D geological model in our study area. The data are unevenly distributed, and only part of the study area was covered by the AEM survey. Cross-cutting tunnel valleys, erosional unconformities, delta units and a large glaciotectonic complex are among the geological features identified in the area. The geological complexity varies significantly across the model area. A broad geological overview and understanding of the area was obtained by joint cognitive interpretation of the geophysical and the geological data. To address the geological complexity and the very high level of detail gained from the AEM data, the model was constructed as a voxel model with lithofacies attributes supplemented by a number of bounding surfaces. In areas where the geology is not too detailed and complex, the model was constructed manually, whereas automated methods were used to populate voxels in areas with a high complexity. The automated methods comprised clay fraction modelling, which was used where AEM data are available, and stochastic modelling, which was used outside the area covered by AEM data. Our study shows that it is advantageous to combine several modelling methods in areas with varying geological complexity and data density. The choice of modelling methods should depend on the character and coverage of available data and on variations in geology throughout the model area. [ABSTRACT FROM AUTHOR]

Abstract: A highly sensitive and label-free amperometric immunosensor has been developed for the detection of carcinoembryonic antigen (CEA) based on layer-by-layer (LBL) assembly of gold nanoparticles (GNPs), multi-walled carbon nanotubes-thionine (MWNTs-THI) and chitosan (CHIT) on 3-mercaptopropanesulfonic, sodium salt (MPS)-modified gold electrode surface by electrostatic adsorption. The stepwise LBL assembly process of electroactive species on electrode surface was characterized by means of cyclic voltammetry (CV) in PBS. The factors influencing the performance of the resulting immunosensor were studied in detail. The morphologies of MWNTs, MWNTs-THI and GNPs–MWNTs-THI–CHIT were further characterized by transmission electron microscopy (TEM). The immunosensor was highly sensitive to CEA with a detection limit of 0.01ngmL−1 (signal/noise ratio of 3) and the linear range with two concentration intermittences was from 0.5 to 15.0ngmL−1 and from 15.0 to 200.0ngmL−1, respectively. In addition, the prepared immunosensor could be regenerated 10 times with 5M urea solution. When the immunosensor was stored at 4°C and measured intermittently (every 4–6 days), no apparent change was found over 3 months. The immunosensor system showed an excellent reproducibility and stability. [Copyright &y& Elsevier]