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A facile copper-catalyzed intramolecular cyclization for the selective synthesis of isoquinolines and isoquinoline N-oxides in water is described.

Photoinduced mass transfer of azo polymer and azo molecular glass has been intensively investigated under various light irradiation conditions simply using air as the ambient environment. In this work, in order to understand the effects of the surrounding medium on the light-induced process, azo molecular glass microspheres adhered on a substrate were immersed in water and different aqueous solutions, and their mass transfer behavior was investigated by irradiation with linearly polarized light. The microspheres in the aqueous media showed significant deformation through directional mass transfer upon light irradiation and transformed into a series of shape-anisotropic particles as revealed by microscopic observations. Compared with their counterparts upon light irradiation in air, the particles immersed in the aqueous media exhibited larger elongation parallel to the substrate and higher shape anisotropy. Optical simulation showed that this was caused by the alteration of the direction of the electric vibration of the refracted light at the medium-microsphere interface, which controlled the mass transfer behavior. On the other hand, the viscosity of the aqueous media showed no effect on the mass transfer process induced by the irradiation. The photo-thermal effect on the mass transfer behavior was ruled out as the thermal dissipation through a liquid is much more efficient than that through air. On the basis of this, this methodology was also successfully employed in the photo-fabrication of anisotropic submicron-sized periodic structures in aqueous medium. These observations can supply deep understanding of this fascinating process induced by polarized light and extend the scope of its applications.

It remains a challenge to develop highly polymer-based nanocomposite thermal interface materials, which can effectively remove heat developed during the miniaturization of electronic instruments. It has been reported that a large number of graphene-based nanocomposites exhibit excellent performance. However, it is still an issue to construct thermal conductive pathways by orientation arrangements with a low filler volume fraction. Herein, a high-thermal conductivity filler of magnetic carbon nanotube-grafted graphene polyhedra (Co@Co3O4-G) was exploited via the annealing of metal–organic frameworks (ZIF-67). Co@Co3O4-G can improve the thermal conductivity of nanocomposites obviously by forming oriented pathways for phonon transport in an external magnetic field. Therefore, the resulting nanocomposite displayed a high thermal conductivity of 2.11 W m−1 K−1 for only 8.7 vol%, which is 10 times higher than that of the pure epoxy resin. Core-shell magnetic cobalt oxide (Co@Co3O4) was encapsulated in situ in the nanoarchitecture to avoid falling off. Moreover, the equilibrium molecular dynamics (EMD) simulation verifies that Co@Co3O4-G had high thermal conductivity to effectively improve the heat dissipation of nanocomposites. This strategy provides an approach for developing high-performance thermal management materials and opens up the possibility for the pioneering applications of encapsulated magnetic-oriented thermal conductive fillers.

Photoinduced surface-relief-gratings (SRGs) on azo polymer and azo molecular glass films, caused by trans–cis isomerization of azo chromophores, have attracted wide interest for their intriguing nature and many possible applications in recent years. Understanding the mechanical properties of SRGs at the nanoscale is critically important for elucidating their formation mechanism and exploring their applications. In this work, a representative azo polymer (BP-AZ-CA) and a typical azo molecular glass (IAC-4) were comparatively studied for the first time concerning their properties related to SRG formation through a variety of methods. The results indicate that when inscribing SRGs on the films, IAC-4 shows a much higher efficiency for forming SRGs relative to that of BP-AZ-CA. The overall average moduli of SRGs measured by nanomechanical mapping techniques are obviously smaller compared with the moduli of the corresponding films of both materials. The moduli at different regions of SRGs are periodically varied along the grating vector direction for both BP-AZ-CA and IAC-4 gratings. The moduli at the trough regions of SRGs are always larger than those of the crests, while the moduli at the hillsides are the smallest. Distinct from BP-AZ-CA, even the moduli at the trough regions of IAC-4 SRG are smaller compared with that of the original film, and the ratio between the trough and crest moduli is significantly larger for IAC-4. These results provide deep understanding of the SRG formation mechanism and reveal the clear distinction between these two types of glassy materials for their SRG-forming behavior, which are important for future applications.

A highly efficient pretreatment strategy using ethylene glycol with dilute sulfuric acid was developed for the fractionation of lignocellulose. The pretreatment behaviors were related to the composition analysis and structure of the samples analyzed by SEM, XRD, FTIR and 2D HSQC NMR, resulting in 80.3% delignification and 84.7% retention of cellulose under the selected conditions (120 °C, 60 min, and 0.6 wt% H2SO4 (w/w)). The enzymatic hydrolysis sugar yield significantly increased from 24.1 to 70.6% (3 FPU g−1), which displayed immense improvement compared with untreated corn stover (24.1%), nearly 3-fold higher than its untreated counterparts. Besides, the regenerated lignin could be fitted to valorize renewable aromatic chemicals and alkane fuels. The present study shows that the pretreatment is a simple, efficient and promising process for corn stover biorefinery.

The effect of the introduced base sites in CsX with alkali oxide modification towards side-chain alkylation of toluene with methanol was systematically investigated in the present work. A series of alkali oxide modified CsX with a base properties (base strength and amount) gradient were prepared by impregnating CsX with alkali metal hydroxide. Here, CsX with different base strengths were selected as the parent zeolite, which is favorable to clarify the different types of base site in the modified CsX. The base properties of the samples were elucidated based on the CO2-TPD results as well as with characterization by XPS and FT-IR of adsorbed CO2. It was revealed that the base strength of the oxygen atoms with negative charge (Oδ−) in the zeolite framework can be strengthened by the electron donating function of the alkali oxides in the supercage of CsX. Detailed analysis of the correlation between the reaction behaviors of side-chain alkylation reaction and the base properties of the indicated catalysts was carried out. It was found that the dehydrogenation of methanol to formaldehyde step was promoted by the increasing base properties of Oδ− in the CsX framework and that was the main reason for the promotion of the whole side-chain alkylation reaction. However, it was also found that the stronger base properties of the alkali oxide modified CsX would enhance the formation of active hydrogen atoms, which aggravated the unwanted styrene conversion to ethylbenzene.

The extensive employment of engineered nanoparticles (NPs) makes it inevitable that the environment would be exposed to nano-materials. As a result, their biological effects on the ecosystem and living organisms are gaining attention. Here, we report that both nano-silica (SiO2-NPs) and reserpine can elicit depression-like behavior in adult zebrafish in a novel tank test. Nano-silica or reserpine induce the depressive phenotype by decreasing locomotion, inhibiting exploratory behavior, aggravating the depressive phenotype and disturbing swimming patterns. Immunohistochemistry reveals that the dampened locomotion induced by nano-silica and reserpine is associated with the reduced expression of tyrosine hydroxylase. Inhibited exploratory behavior, aggravated depressive phenotypes, and disturbed spatiotemporal swimming path patterns are related to the increased expression of serotonin. These findings imply that the similar behavioral and depression-inducing effect of nano-silica and reserpine may share a common physiological mechanism. In summary, our results suggest that exposure to silica nanoparticles in the nervous system is a possible depression-inducing factor.

Here we report a general method for the de novo synthesis of a bicyclo[6.1.0]nonyne group containing an amino acid, and used Marfey's reagent for chiral analysis. This unnatural amino acid offered exceptional reactivity in the inverse electron demand Diels–Alder cycloaddition with tetrazine containing amino acids. The subsequent selective labeling of living cells at low dye concentrations demonstrated the usefulness of the new amino acid for future imaging studies. This work also laid the foundation for introducing this unnatural amino acid into peptides based on the solid-phase synthesis method.

Pd-doped SnO2 hollow spheres were synthesized via a facile one-step hydrothermal route. Utilized as the materials in sensors, the 3.0 wt% Pd-doped SnO2 demonstrated more excellent gas-sensing properties towards CO than 1.5 wt% and 4.5 wt% Pd-doped SnO2. Compared with the SnO2 hollow spheres gas sensor, the optimum operating temperature of the Pd-doped SnO2 hollow spheres gas sensor dropped to 200 °C from 250 °C; the response value to 100 ppm CO was raised to 14.7 from 2.5 accordingly. Furthermore, the response and recovery times of the 3.0 wt% Pd-doped SnO2 sensor are 5 s and 92 s, respectively, to 100 ppm CO at 200 °C. It is believed that its enhanced gas-sensing performances are derived from the synergistic interactions between the dispersed Pd and the characteristic configuration of the SnO2 hollow sphere. In addition, theoretical calculations have also been performed with periodic slab models by using density functional theory, which explain well our experimental phenomenon.

Manganese oxide nanoparticles (MONs) have received growing attention as alternative T(1) MRI contrast agents due to the association of commercial gadolinium-based contrast agents with nephrogenic systemic fibrosis. Since the seminal publication first describing the use of MONs as positive T(1) contrast agents, there is an ongoing impetus to develop MONs of higher T(1) signal intensity for better diagnostic efficacy. Indeed, various MON-based nanoprobe designs have been proposed, such as the employment of a mesoporous nanomaterial with MONs evenly dispersed within, or the traditional coating of a biocompatible layer onto the surface of MONs to form a core–shell configuration. Recent advances in this field also propose stimuli-responsive MONs that capitalize on an acidic dissolution or in situ reduction to release Mn(2+) ions for a multi-fold increase in MRI contrast. However, the potential nanotoxicity of MONs remains a key obstacle to the clinical translation of MON-based T(1) contrast agents. Due to the wide variety of functionalities and physicochemical properties of MONs, there is also a lack of consensus on the toxicological properties of MONs. In addition, the r(1) relaxivity of MRI contrast agents typically decreases at higher field strength. Hence, it highlights the need to develop MON-based contrast agents with higher relaxivities. In this regard, this article aims to present a thorough review of MONs for MRI applications, with particular emphasis on their relaxivity and toxicological properties. In order to systematically review the current state-of-the-art for the development of MONs for MRI applications, the MON-based T(1) contrast agents are categorized based on the structure of the nanomaterial system. Key parameters that influence the nanotoxicity of MONs are also examined while the absorption, distribution, metabolism and excretion of MON in vivo are evaluated to discern how long the nanoparticles will be present within the body, as well as to predict the organs or tissues in which they distribute.

A carbon matrix with an appropriate porous structure plays a vital role in developing high-performance sulfur/carbon cathodes of lithium–sulfur batteries. In this work, a hierarchical porous carbon fiber (HPCF) with a few mesopores and abundant micropores was prepared via electrospinning with a SiO2 template and subsequent KOH activation. The HPCF with an ultra-high surface area and a large pore volume can construct a loose network structure to promise high sulfur utilization and sufficient sulfur loading. Mesopores can provide pathways for the infiltration of electrolyte to ensure fast transport of lithium ions during electrochemical reactions, whereas micropores can effectively suppress the diffusion of polysulfides by their strong adsorption capability. Due to such advantages, the proposed cathode, with 66 wt% sulfur content, can yield a high reversible capacity of 1070.6 mA h g−1 at 0.5C, and a stable cycle performance with a capacity retention of 88.4% after 100 cycles.

In this study, we employed zebrafish as an animal model to evaluate the biological effect of polyhydroxyalkanoates (PHAs) on early development via morphological, physiological, and behavioural analyses. Developmental results indicated no obvious adverse effects of PHAs on the development of zebrafish embryos and larvae, except the occurrence of krox20 expression fluctuation. Furthermore, standard and colour-enriched open field tests were conducted to assess the natural colour preference/avoidance behaviour of zebrafish larvae as well as the effect of PHA concentration on patterns of exploratory behaviour and natural colour preference/avoidance. The behavioural results were as follows: (1) compared with un-injected larvae, PHA-injected larvae displayed enhanced exploratory behaviour with decreased thigmotaxis (central avoidance) in the open field test and increased thigmotaxis (central avoidance) in the colour-enriched open field test. (2) PHA injection attenuated anxiety-like behaviour by decreasing latency prior to exploration. (3) PHAs increased the preference for blue, red and black colours. In conclusion, PHAs have a concentration-dependent effect on strengthening exploratory behaviour, lessening anxious behaviour and altering the colour preference/avoidance patterns of larval zebrafish. These results suggest that PHAs have a potential effect on the behaviour of zebrafish.

The readily available CuSO4-H-phosphonate catalytic system can catalyze the head-to-head dimerization of terminal alkynes to give the corresponding (E) conjugated enynes selectively in high yield. The present protocol provides an efficient and practical approach to various conjugated enynes with the advantages of cheap catalysts, operational simplicity and high stereo-and regioselectivity.

N-Isopropylacrylamide (NIPAA) based cucurbit[7]uril (CB[7]) side-chain polypseudorotaxanes with low pseudorotaxane content were designed with the intention to emulate rod-coil block copolymers. In the polypseudorotaxanes, CB[7] pseudorotaxane units acted as rigid “rod segments” and the remaining polymer chain acted as the “soft-coils”. The length of soft-coil segments, which determines the aggregation behavior, can be easily tuned by changing the CB[7] pseudorotaxane content. The polypseudorotaxanes with much lower pseudorotaxane content demonstrate unique aggregation behavior, with a strong tendency for aggregation and thermal gelation. Their aggregation behavior and the formed hydrogels were studied with dynamic light scattering (DLS), and rheological and microscopic experiments. The mechanism of the unique aggregation behavior was also investigated.

In this paper, a new bismuth(III) Schiff-base complex [Bi9O8(vanen)3(NO3)2(CH3OH)2(H2O)]·3NO3·5.5H2O was synthesized by reaction of [H2vanen = N,N′-ethylene bis(3-methoxysalicylideneimine)] and Bi(NO3)3·5H2O in methanol at 45–60 °C. The inhibitory effects of the complex and its ligand on Schizosaccharomyces pombe (S. pombe) growth were investigated by microcalorimetry. The experimental results indicated the complex had a stronger inhibitory activity towards S. pombe than that of the ligand. The interaction between bovine serum albumin (BSA) and the complex under physiological conditions was studied by fluorescence spectroscopy. The complex had a quite strong ability to quench the fluorescence of BSA and their combination reactions were a static quenching process. The complex could bind BSA via a binding site and the binding distance r was 3.52 nm. The synchronous fluorescence spectroscopy further revealed that the complex had partly inserted into the hydrophobic pocket of BSA.

Increasing the sulfur loading in the cathode of a lithium–sulfur battery is an important way to improve its capacity for practical applications. To achieve this, the present work proposes using PEDOT-PSS to encapsulate sulfur/carbon black (S/BP) by a facile solution mixing method and the formed composite is then coated on a porous carbon paper. It is believed that the formation of a core/shell structure in the PEDOT@S/BP composite can promote the electron transport and effectively impede the diffusion of polysulfides, and the porous carbon paper is able to retain the electrolyte containing the dissolved polysulfides in the cathode and alleviate the adverse effect of sulfur volumetric expansion. Due to such advantages, the proposed cathode, with a high sulfur loading of 3 mg cm−2, can yield a high reversible capacity of 1041 mA h g−1 and an excellent cycle stability with a capacity retention of 868 mA h g−1 after 100 cycles and an average coulombic efficiency of 99.4%.