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The nitrogen reduction reaction (NRR) has become an ideal alternative to the Haber‐Bosch process, as NRR possesses, among others, the advantage of operating under ambient conditions and saving energy consumption. The key to efficient NRR is to find a suitable electrocatalyst, which helps to break the strong N≡N bond and improves the reaction selectivity. Molybdenum disulfide (MoS2) as an emerging layered two‐dimensional material has attracted a mass of attention in various fields. In this minireview, we summarize the optimization strategies of MoS2‐based catalysts which have been developed to improve the weak NRR activity of primitive MoS2. Some theoretical predictions have also been summarized, which can provide direction for optimizing NRR activity of future MoS2‐based materials. Finally, an outlook about the optimization of MoS2‐based catalysts used in electrochemical N2 fixation are given.

Hydrogen (H2) molecules are easy to leak during production, storage, transportation and usage. Because of their flammability and explosive nature, quick and reliable dectection of H2 molecule is of great significance. Herein, an excellent H2 gas sensor has been realized based on Pd nanocrystal sensitized two-dimensional (2D) porous TiO2 (Pd/TiO2). The formation of 2D porous TiO2 with the removal of graphene oxide template has been monitored by an in-situ transmission electron microscope. It is found that the size of the GO template can be almost completely replicated by 2D TiO2. The Pd/TiO2 sensor exhibited an instantaneous response and a satisfactory low detection limit for H2 detection. These excellent gas-sensing performances (good selectivity, unique linearity response and high stability) can be attributed to the unique 2D porous structure and the synergistic effect between oxidized Pd and TiO2, including the unique adsorption properties of O2 or/and H2 on Pd/TiO2, the reaction between PdO and H2 gas, and the regulated depletion layer arising from p-type PdO to n-type TiO2. This work demonstrates a rational design and synthesis of highly efficient H2 sensitive materials for energy and manufacturing security.

Polychlorinated biphenyls (PCBs), a group of persistent organic pollutants, are ubiquitous in the environment. The concentrations of PCBs and their metabolites are crucial to understand their impac...

With the rapid development of energy sources and aerospace engineering, high-performance thermal insulation materials with multiple functions are attracting more and more attentions. Non-oxide ceramic aerogels have application potential in thermal insulation under harsh conditions owing to their good thermal insulation performance and chemical stability. In this work, TiN aerogels were prepared by a combined freeze-casting and carbothermal reduction-nitridation method utilizing TiO2 and chitosan as raw materials, at 1473 K for 3 h, with a C/TiO2 molar ratio of 3/1. They showed a specific surface area of 167 m2/g and ultralow density of 0.07 g/cm3 (the relative density of 1.3 %). Their thermal conductivity value was only 0.166 ± 0.0054 W/(m K at 673 K (TiO2 solid content of 5 wt%). Moreover, the prepared aerogels possessed reasonably high mechanical strength and good high-temperature service performance, suggesting that they can be used under high-temperature conditions as an insulation material.

Various electrochemical biosensors have been developed for direct and real-time recording of biomolecules released from living cells. However, since these traditional electrodes are commonly rigid and nonflexible, in situ monitoring of biochemical signals while cell deformation occurs remains a great challenge. Herein, we report a facile approach for the development of a stretchable and transparent electrochemical cell-sensing platform based on Au nanostructures (nano-Au) and carbon nanotube (CNT) films embedded in PDMS (nano-Au/CNTs/PDMS). The sandwich-like nanostructured network of nano-Au/CNTs endows the sensor with excellent mechanical stability and electrochemical performance. The obtained nano-Au/CNTs/PDMS electrode displays desired performance for H2O2 detection with a wide linear range (20 nM-25.8 μM) and low detection limit (8 nM). Owing to good biocompatibility and flexibility, HeLa and human umbilical vein endothelial cells can be directly cultured on the electrode and real-time monitoring of H2O2 release from cells under their stretched state was realized. The proposed strategy demonstrated in this work provides an effective way for design of stretchable sensors and more opportunities for sensing biomolecules from mechanically sensitive cells.

Graphitic carbon nitrides have CO2 photoreduction ability, but their activities are limited by the low potential and mobility of photogenerated carriers. Herein, ultrathin mesoporous graphitic carbon nitride nanosheets (CNNS) synchronously decorated with functional cyano groups and nitrogen vacancies were prepared by a facile molten salt route. The CNNS presented unprecedentedly excellent gas-phase CO2 photoreduction performance under visible light irradiation without any co-catalyst or a sacrificial agent, and have a CH4-yielding rate of 23.0 μmol g−1 h−1 and a selectivity of 97.9%. This boosted performance can be attributed to the synergistic effect of cyano group decoration, abundant nitrogen vacancies and extremely high surface area, which improve electron storage, charge carrier mobility, CO2 affinity, and optimize the energy band structure. This work demonstrates that a structural optimization combined with defect design of carbon nitride framework is a powerful approach to improve the photocatalytic activity, providing an accessible way to design highly efficient carbon-based photocatalysts.

Based on the signal amplification elements of planar VS2/AuNPs nanocomposites and CoFe2O4 nanozyme, we herein developed an electrochemical biosensor for sensitive kanamycin (Kana) quantification. A ratiometric sensing platform was presented by incorporating VS2/AuNPs nanocomposites as a support material with excellent conductivity and high specific surface area, as well as hairpin DNA (hDNA) with complementary hybridization of biotinylated Kana-aptamer. In addition, streptavidin-functionalized CoFe2O4 nanozyme with superior peroxidase-like catalytic activity were immobilized onto the aptasensor, hence the peroxidase-like catalytic reaction could yield amplified electrochemical signals. With the presence of Kana, the aptamer-biorecognition resulted in a quantitative decrease of nanozyme accumulation and an increase of methylene blue response. Under optimal conditions, the electrochemical signal ratio of the aptasensor revealed a linear relation along with the logarithmic concentration of Kana from 1 pM to 1 μM, with the limit of detection reaching to 0.5 pM. Moreover, this aptasensor exhibited excellent precision, as well as high repeatability, hence possessing potentials in real samples and for diverse targets detection by easy replacement of the matched aptamer.

International audience; With an aim to enhance the stability and volatility of the heterometallic derivative [SnCl4(µ-OEt)2Ti(OEt)2(HOEt)2] (A), obtained conveniently and quantitatively as a simple adduct formula from the equivalent reaction of commercially available SnCl4 and Ti(OEt)4 in toluene/ethanol, its modification with 2,2,6,6-heptane-3,5-dione (thdH) is reported. The modified precursor [SnCl4(µ-OEt)2Ti(thd)(OEt)(HOEt)] (1), obtained from equimolar reaction of A and thdH, is stable at room temperature but rearranges on heating into A and [SnCl4(µ-OEt)2Ti(thd)2] (2), as confirmed by the vapor pressure measurements and DFT calculations. The heterometallic 2 can be obtained in excellent yield from the reaction of A and thdH in 1:2 molar ratio and is stable in solid and solution phase up to 200 °C. However, the asymmetric nature of its structure consisting of fragments of titanium β-diketonate and tin chloride connected by bridging ethoxo groups, leads to breakdown into two homometallic components in gas phase, leading to deposition of tin-rich metal oxide films on the substrate.

Background Thermoanaerobacter ethanolicus produces a considerable amount of ethanol from a range of carbohydrates and is an attractive candidate for applications in bioconversion processes. Due to the coupling of hydrogenase activity with fermentation product distribution, understanding hydrogen production of T. ethanolicus, particularly the genes responsible, is valuable for metabolic engineering of the species. Results Utilizing the hydrogenases reported in Thermoanaerobacterium saccharolyticum and Pyrococcus furiosus as templates, BLAST search identified five hydrogenase gene clusters, including two membrane-bound [NiFe] hydrogenases ech and mbh, two cytoplasmic [FeFe] hydrogenases hyd and hydII, and one cytoplasmic [NiFe] hydrogenase shi. The combined deletion of ech, mbh, shi and hydG resulted in a strain that did not produce hydrogen and showed no methyl viologen hydrogenase activity in cell extracts. Strains with deletions of all the hydrogenases except one showed normal hydrogen production. Methyl viologen hydrogenase activity was greatly reduced in all combined deletion strains except the strain with an intact hydG gene. Conclusion High hydrogen production and hydrogenase activities have been observed for T. ethanolicus. Five hydrogenases have been identified. Hydrogen production was eliminated by deleting genes required for all five hydrogenases. Each individual hydrogenase was verified to be capable of producing hydrogen during fermentation, indicating a high degree of redundancy and flexibility in the hydrogenase systems of T. ethanolicus. A large portion of hydrogenase activity is encoded by the [Fe-Fe] hydrogenases.

Clostridium thermocellumis a thermophilic, anaerobic, bacterium that natively ferments cellulose to ethanol, and is a candidate for cellulosic biofuel production. Recently, we identified a hypermutator strain ofC. thermocellumwith a C669Y mutation in thepolCgene, which encodes a DNA polymerase III enzyme. Here we reintroduce this mutation using recently-developed CRISPR tools to demonstrate that this mutation is sufficient to recreate the hypermutator phenotype. The resulting strain shows an approximately 30-fold increase in the mutation rate. This mutation appears to function by interfering with metal ion coordination in the PHP domain responsible for proofreading. The ability to selectively increase the mutation rate inC. thermocellumis a useful tool for future directed evolution experiments.ImportanceCellulosic biofuels are a promising approach to decarbonize the heavy duty transportation sector. A longstanding barrier to cost-effective cellulosic biofuel production is the recalcitrance of the material to solubilization. Native cellulose-consuming organisms, such asClostridium thermocellum, are promising candidates for cellulosic biofuel production, however they often need to be genetically modified to improve product formation. One approach is adaptive laboratory evolution. Our findings demonstrate a way to increase the mutation rate in this industrially-relevant organism, which can reduce the time needed for adaptive evolution experiments.

This work proposed a novel and flexible immunosensor for highly selective and sensitive determination of cortisol in sweat. The flexible electrode was developed by transferring multi-walled carbon nanotubes (MWCNTs) film on polydimethylsiloxane (PDMS) substrate and subsequent electrochemical deposition of Au nanoparticles (AuNPs) on the MWCNTs surface. The obtained AuNPs/MWCNTs/PDMS electrode was then covalently immobilized with anti–cortisol monoclonal antibody (Anti-Cmab) and blocked with BSA. Scanning electron microscope confirmed that MWCNTs have been firmly combined with PDMS and AuNPs distributed uniformly on the surface of MWCNTs. The PDMS-based sensor possesses a good mechanical stability against stretching, bending and twisting, displaying stable electrochemical performance under deformation. After optimizing the analytical parameters, the developed immunosensor allowed a facile quantification of cortisol in the range of 1 fg/mL–1 μg/mL with a detection limit of 0.3 fg/mL. The cortisol immunosensor was further used to evaluate cortisol levels in human sweat, and the results corresponded closely with commercially available chemiluminescence immunoassay (CLIA) method. Results indicated that the new cortisol immunosensor could provide an effective tool for the noninvasive, point of care measurement of sweat cortisol levels and is promise to be a wearable biosensor for the healthy monitoring.

Background Biofuel production from plant cell walls offers the potential for sustainable and economically attractive alternatives to petroleum-based products. In particular, Clostridium thermocellum is a promising host for consolidated bioprocessing (CBP) because of its strong native ability to ferment cellulose. Results We tested 12 different enzyme combinations to identify an n-butanol pathway with high titer and thermostability in C. thermocellum. The best producing strain contained the thiolase–hydroxybutyryl-CoA dehydrogenase–crotonase (Thl-Hbd-Crt) module from Thermoanaerobacter thermosaccharolyticum, the trans-enoyl-CoA reductase (Ter) enzyme from Spirochaeta thermophila and the butyraldehyde dehydrogenase and alcohol dehydrogenase (Bad-Bdh) module from Thermoanaerobacter sp. X514 and was able to produce 88 mg/L n-butanol. The key enzymes from this combination were further optimized by protein engineering. The Thl enzyme was engineered by introducing homologous mutations previously identified in Clostridium acetobutylicum. The Hbd and Ter enzymes were engineered for changes in cofactor specificity using the CSR-SALAD algorithm to guide the selection of mutations. The cofactor engineering of Hbd had the unexpected side effect of also increasing activity by 50-fold. Conclusions Here we report engineering C. thermocellum to produce n-butanol. Our initial pathway designs resulted in low levels (88 mg/L) of n-butanol production. By engineering the protein sequence of key enzymes in the pathway, we increased the n-butanol titer by 2.2-fold. We further increased n-butanol production by adding ethanol to the growth media. By combining all these improvements, the engineered strain was able to produce 357 mg/L of n-butanol from cellulose within 120 h. Electronic supplementary material The online version of this article (10.1186/s13068-019-1524-6) contains supplementary material, which is available to authorized users.

Spinel LiMn2O4 powders have been hyper-rapidly produced by a microwave-induced solution flameless combustion method (MISFC) for 5 min using lithium nitrate, manganese acetate and nitric acid as raw materials. The XRD data indicate that the phase composition is severely affected by the molar ratio of NO3−:Ac− (N:A). The LiMnO2 and Mn3O4 impurities successively disappear along with the increase of the N:A ratio. The pure LiMn2O4 product prepared at 1:1 is composed of polyhedral crystals with submicron size. Its initial discharge specific capacity reaches 114.4 mAh g−1 at 1C and there is still 52.0 mAh g−1 at the 1000th cycle. The XRD and TEM data suggest that the sample showed excellent stability during long cycles.

The objective of this investigation was to evaluate the influence of back-fat thickness (BF), at mating of sows, on the placental oxidative stress, mitochondrial injury and apoptosis. For that purpose, we performed iTRAQ labeling based proteomic analysis on term placentas obtained by vaginal delivery from BFI (15–20 mm) and BFII (21–27 mm) sows formed according to BF at mating. Proteomic analysis revealed 413 proteins to be significantly different in placenta from BFII sows by ≥1.2-fold. Gene ontology (GO) analysis identified proteins related to oxidative stress response and apoptotic process to be altered in placenta from BFII sows. Indicative of increased oxidative stress and impaired mitochondrial function, higher placental MDA, H2O2 and O2− levels and reduced CAT and SOD activities were linked to decreased mitochondrial membrane potential and reduced mitochondrial DNA copy number and increased MPTP opening activity in placenta from BFII group (P

The dry sliding wear behavior of Ti2AlC reinforced AZ91 magnesium composites was investigated at sliding velocity of 0.5 m/s under loads of 10, 20, 40 and 80 N using pin-on-disk configuration against a Cr15 steel disc. Wear rates and friction coefficients were registered during wear tests. Worn tracks and wear debris were examined by scanning electron microscopy, energy dispersive X-ray spectrometry and transmission electron microscopy in order to obtain the wear mechanisms of the studied materials. The main mechanisms were characterized as the magnesium matrix oxidation and self-lubrication of Ti2AlC MAX phase. In all conditions, the composites exhibit superior wear resistance and self-lubricated ability than the AZ91 Mg alloy. In addition, the anisotropic mechanisms in tribological properties of textured Ti2AlC-Mg composites were confirmed and discussed.

In this article, we demonstrated an extremely high-sensitivity formaldehyde (HCHO) gas sensor, where the graphene oxide (GO) in situ modified two-dimensional (2D) SnO2 nanosheets with in-plane mesopores were utilized as the sensing materials. The sensor response ( Ra/ Rg) was larger than 2000 toward 100 ppm HCHO at 60 °C. In addition, the selectivity for detecting HCHO was excellent against other interferences including ethanol, acetone, methanol, toluene, ammonia, water, etc. The outstanding sensing performance of 2D mesoporous GO/SnO2 nanosheets was attributed to the synergism of the sensitizer effect of GO, large surface areas of 2D nanostructure, suitable particle size, and abundant in-plane mesopores. The high sensitivity, high selectivity, and low working temperature of the sensor reported here endowed it a great potential in selective detection of HCHO. Meanwhile, the design and synthesis of GO/SnO2 nanocomposites will provide new paradigms in the future development of HCHO-sensitive materials.

Clostridium thermocellum is a good candidate organism for producing cellulosic biofuels due to its native ability to ferment cellulose, however its maximum biofuel titer is limited by tolerance. Wild type C. thermocellum is inhibited by 5 g/L n-butanol. Using growth adaptation in a chemostat, we increased n-butanol tolerance to 15 g/L. We discovered that several tolerant strains had acquired a D494G mutation in the adhE gene. Re-introducing this mutation recapitulated the n-butanol tolerance phenotype. In addition, it increased tolerance to several other primary alcohols including isobutanol and ethanol. To confirm that adhE is the cause of inhibition by primary alcohols, we showed that deleting adhE also increases tolerance to several primary alcohols.

In recent years, some composite insulators operating in coastal foggy areas have shown different levels of degradation phenomena. This paper presents several performances and properties of silicone rubber under the salt-fog environment with AC voltage. Analysis conducted after salt-fog treatment by techniques, such as static contact angle, Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), dielectric parameter, and flashover voltage show a significant degradation of samples. The absorption peak of the hydrophobic groups (Si-(CH3)2 and Si-CH3) decreased, the surface of the material became rough, and the dielectric and electrical properties were also deteriorated. Due to the thermal effects and impact of high-energy particles, the molecular chains on the surface of silicone rubber were broken, and the smooth surface structure was destroyed, resulting in the formation of hydrophilic chemical bonds and precipitation of inorganic substances. The intrusion of moisture further reduces the dielectric parameters and the electrical strength of the material. In addition, the samples in the salt-fog environment with a greater conductivity are more degraded, indicating that the salt-fog has an aggravating effect on the aging of the silicone rubber. Thus, it is recommended to pay attention to the monitoring and examining the work of composite insulators operating in a foggy and high humidity environment.

The evolutions with the temperature of damping capacities and dynamic Young's moduli of ternary Ti2AlC particles reinforced AZ91D composites were investigated. This work has highlighted that Ti2AlC significantly contributes to the damping capacity and to dynamic moduli of composites. With increasing temperature, especially above 200 °C, the interfacial damping capacity becomes dominant and dynamic moduli of composites decrease. These trends were revealed from the transformed tensile fracture mechanisms. At room temperature, Ti2AlC particles delaminated without any decohesion between Ti2AlC particles and the Mg matrix. However, the interfacial decohesion occurred above 200 °C. One explanation of this change of decohesion mechanism could be ascribed to the inherent structure of the Ti2AlC MAX phase and to the formation of a robust amorphous magnesium layer at the interface between Ti2AlC and magnesium matrix that was evidenced by HRTEM. This amorphous layer further gives rise a high activation energies (H) of damping peaks for composites, which was calculated to 128 kJ/mol. This value is higher than those calculated for SiC or graphite reinforced AZ91D composites, making Ti2AlC particles particularly interesting for application in reinforcing magnesium composites.

Hierarchical porous N-doped carbon submicrospheres (HPNCs) are synthesized at 1000 °C by a facile molten salt method using diaminomaleonitrile as a precursor, iron trichloride as a catalyst, and ZnCl2-KCl to form the molten salt medium. The results indicated that the pore structure of resultant HPNCs could be tuned by changing the amount of iron catalyst, and those prepared with adding 7.1 wt% FeCl3·6H2O showed the highest specific surface area (3155 m2/g) and largest hierarchical pore volume (2.2 cm3/g) with micropore and mesopore surface areas of 808 m2/g and 2347 m2/g, respectively, in addition to their high mesopore ratio up to 84.4%. The resultant HPNCs showed outstanding specific capacitance up to 455 F/g in 6 M KOH electrolyte solution at a current density of 0.5 A/g, a considerably high energy density of 93.6 Wh/kg and high capacitance retention of 95% after 5000 cycles. Moreover, they exhibited high adsorption capacities of 812.2 mg/g and 805.2 mg/g, for methylene blue and methyl orange adsorption, respectively, and high CO2 adsorption capacity of 3.4 mmol/g at 25 °C and at an equilibrium pressure of 1 bar.

A novel kind of hydroxypropyltrimethyl ammonium chloride chitosan (HACC) mixed colloid was developed to improve the hydrophilicity of silicone hydrogel films (SHFs) via self-assembly. The contact angle of the modified SHF decreased from 33.24° to 12.98°, whereas the atomic force microscopy image verified that the roughness of the modified films decreased and indicated that the HACC mixed colloids filled in the interstices on the surface of the SHF. A new method of capacitance was developed to characterize the electric charge value, the groups, and the microscopic conditions of the self-assembled SHF surface for the first time. Cyclic voltammetry and chronopotentiometry exhibited that the capacitance of the SHF increased to 0.0196 F/g, which indicated the enhanced positively charged surface and increased the number of hydrophilic quaternary ammonium groups on the surface. Lipid adsorption analysis also revealed that the modified SHF possessed a weaker lipid adhesion ability and stronger lipid removal ability than those of the original SHF and hence showed promising features for application in ophthalmological products.

Herein, we report a facile enzyme-free microRNA (miRNA) target-triggered strand displacement reaction (SDR) amplification strategy with ferrocene (Fc) as a signal molecule to fabricate a two-dimensional electroactive molybdenum carbide (Mo2C)-based biosensor. In the presence of miRNA-21, SDR was initiated and many hairpin DNA1 (HDNA1) and hairpin DNA2 (HDNA2) duplexes, which could be captured by probe DNA leading the Fc-modified HDNA2 close to the electrode surface, were produced continuously. MiRNA-21 could be detected by monitoring the redox signal of Fc. The prepared N-carboxymethyl chitosan/Mo2C nanocomposite featured excellent conductivity, great dispersion, and multiple functional groups (amine groups). When the nanocomposite was introduced to a miRNA biosensor electrode interface to ensure its strong connection to the DNA probe, the developed miRNA-21 biosensor demonstrated a reliable linear range of 1.0 fM to 1.0 nM with a detection limit of 0.34 fM and showed good selectivity, reproducibility, and stability. The biosensor was employed to detect miRNA-21 in human serum samples, and it showed great potential in the early clinical diagnosis of various genetic diseases.

Animals exposure to polychlorinated biphenyls (PCBs) may result in retention of hydroxylated PCBs (OH-PCBs). OH-PCBs can be accumulated in animals, including humans, through the transmission of food chain. However, there are few studies on the accumulation and metabolism of OH-PCBs exposed to the body through daily diet. Therefore, this study was conducted to investigate the fate of OH-PCBs after being ingested through dietary intake. By adding 3-OH-PCB101 and 4-OH-PCB101 to the edible tissue of crucian carp, which were used as raw materials to prepare mouse feed, with an exposure concentration of 2.5 μg/kg ww. The exposure experiment lasted for a total of 80 days. The blood, feces and 11 tissues of mice at different times were analyzed qualitatively and quantitatively. It was found that major OH-PCB101 were accumulated in intestine or excreted with feces. A small part was accumulated in heart, lung and spleen. For the first time that the conversion from OH-PCB101 to PCB101 in mice was discovered, which shows from another perspective that persistent organic pollutants are difficult to be completely degraded in the environment. 4-MeO-PCB101, 3-MeSO2-PCB101, and 4-MeSO2-PCB101 were also found in various tissues. The results of this study show that after OH-PCBs accumulated in animals re-enter the organism through the food chain, they can be metabolized again and may be reversely transformed into the parent compounds. The present research shed new light on simulating the metabolic transformation process of OH-PCBs exposed to mammals through ingestion of fish. Available data show that second-generation persistent organic pollutants in the environment still need to be continuously concerned.

The intensive aquaculture strategy and recirculating aquaculture system often lead to the production of off-flavor compounds such as 2-methyl-isoborneol (2-MIB) and Geosmin (GSM). The regular purge and trap extraction followed by analysis with gas chromatography-mass spectrometry (GC-MS) usually involve a complicated assembly of facilities, more working space, long sample preparation time, and headspace solid-phase microextraction (SPME). In this work, a method with easier sample preparation, fewer and simplified facilities, and without SPME on GC-MS analysis is developed for the determination of 2-MIB and GSM in fish samples. Unlike previous methods, solvent extract from samples, QuEChERS-based cleanup, and solid-phase extraction for concentration are applied. The LOD (S/N > 3) and LOQ (S/N > 10) of this method were validated at 0.6 μg/kg and 1.0 μg/kg for both 2-MIB and GSM, which are under the sensory limit (1 μg/kg). Application of this method for incurred fish samples demonstrated acceptable analytical performance. This method is suitable for large-scale determination of 2-MIB and GSM in fish samples, owing to the use of simple facility and easy-to-operate procedure, rapid sample preparation, and shorter time for GC-MS analysis without SPME.

In order to improve its aqueous solubility and emulsifying function, zein was partially hydrolyzed by trypsin and conjugated to chitosan oligosaccharide lactate by transglutaminase. Hydrolysis and covalent linkage to chitosan oligosaccharide was confirmed by free amine content, gel electrophoresis, and infrared spectroscopy. Enzymatic glycosylation was optimized at pH 6, 44 °C, and 4 h to bind approximately 95% of the free amines in the hydrolysates to chitosan oligosaccharide. Hydrolysis and conjugation increased solubility of zein by 47.60% and 72.93%. Hydrolysis and conjugation also decreased surface hydrophobicity by more than 20% and more than doubled emulsifying activity index, emulsion stability index, and foaming capacity. This enzymatic modification has potential to be applied to improve functional properties of other prolamins.

Owing to their large specific areas, high thermal stability and chemical inertness, two-dimensional boron carbon nitride nanosheets (BCNNs) have captured much attention in recent years in the field of adsorption of pollutants. The formation of BCNNs via incorporating carbon into boron nitride (BN) can effectively improve the photoelectric and adsorption properties of the latter. In this work, carbon-doped BN (BCN) nanosheets were prepared at 1100 °C via a molten salt route using boric acid, melamine and glucose as the main starting materials. The effects of molten salt type and carbon doping level on the formation of BCN were investigated, and their isothermal adsorption properties in a methylene blue (MB) aqueous solution were evaluated based on the Langmuir and Freundlich models. The results indicated that using molten LiCl-KCl as a liquid medium was more favorable than NaCl-KCl to the formation of BCNNs. As-prepared BC0.4N sample possessed a sheet-like structure of about 10 nm thick and a specific surface area as high as 484 m2 g−1. Moreover, the adsorption test of MB demonstrated a high adsorption capacity of 249.04 mg g−1, which was about 14 times higher than that in the case of the pristine BN, and the kinetic rate constant value in the case of using BC0.4N is about ten times as high as that of BN following a pseudo-second-order model, suggesting that the as-formed BC0.4N nanosheets could be potentially used as a value-added effective adsorbent for future wastewater remediation.

The efficiency of the superconducting radio frequency cavities composed of Nb required the deposition of thickness-controlled multilayer coatings of superconductor-insulator-superconductor (S-I-S) on the internal surfaces of the cavities. Herein, we report the plasma-enhanced atomic layer deposition of carbon-free NbN (50 µm thick), followed by a thermal treatment, to obtain the superconducting layer in the S-I-S structure. Using (tert-butylimido)-tris(diethylamino)-niobium as the niobium precursor and H2 and NH3 plasma as reactive gasses, the deposition and annealing parameters were optimized by studying their effects on the film properties (crystallinity, density, and composition). We demonstrated that the superconducting critical temperature (Tc) can be improved after thermal annealing up to 13.8 K, a value compatible with the targeted application. In addition to the expected densified layers and increased grain size, we observed a partial transformation of the oxide present in the as-deposited layer into niobium oxynitride, which could indicate the origin of the improvement of the superconducting properties. With low carbon and oxygen impurity concentrations in the films, this study contributes to the understanding of the relationship between the structure, composition, and superconductivity in NbN.

The rational design of nanomaterials with distinct exposed facets is of great importance for improving the physicochemical properties of these materials and for the study of structure–activity relationships. This work describes the first synthesis of lanthanum titanate (La2Ti2O7, LTO) with dandelion-like nanostructures via the molten salt method. The lowest synthesis temperature of 700 °C is at least 200 °C lower than that required by other methods. The dandelion structure consists of well-crystallized LTO nanorods (NRs) with sizes of less than 100 nm in the radial direction and 300–500 nm in the axial direction, which is different from the widely accepted two-dimensional form. LaOCl microplates were formed as an intermediate substrate for LTO NR growth outwards to the basal surfaces of the LaOCl crystallites. DFT calculation results showed that the strong LiCl adsorption on the (100) surface led to distinct growth of the (100) and (020) planes, thus promoting the rod-like growth of LTO along the [010] axis. In addition, the photocatalytic performance of as-prepared LTO was evaluated by determining the degradation of rhodamine B. The results suggested that the as-prepared LTO could markedly enhance the photocatalytic activity as a result of the surface heterojunction of coexposed {100} and {002} facets in LTO NRs. A catalyst that uses light irradiation to decompose organic pollutants can become more active by being fabricated into rod-like nanostructures resembling dandelion seeds. Zhong Huang from the Wuhan University of Science and Technology in China and co-workers have developed a method for synthesizing lanthanum titanate, a ceramic that excels at separating positive and negative photogenerated charges so they can be employed for catalytic reactions. The team’s approach quickly prepares lanthanum titanate nanocrystals using a bath of molten lithium and potassium salts. By optimizing the molten salt concentrations, the researchers isolated tiny aggregates of nanorods that have a high number of exposed crystal facets for charge separation. Experiments showed the nanorods could degrade model pollutants such as rhodamine dyes several times faster than conventional plate-shaped lanthanum titanates. A surface heterojunction is formed in the dandelion-like LTO, resulting in significant enhancement of the photocatalytic performance.

Two-dimensional CdS-based hybrid nanostructures are intriguing materials with an application prospect in different fields such as sensing (i. e., photoresistors) and solar energy harvesting (photocatalysis, photovoltaics, and so forth). We report herein a colloidal synthetic path for interfacing metal and semiconductor with 2D CdS nanoplates. Selective growth of Au, Pt, and a PtNi alloy as well as Cu2−xS semiconductor is achieved on CdS nanoplates using controlled reduction of metallic precursors and thermal decomposition of a metal-sulfide single-source precursor using standard organic-phase colloidal chemistry.

Increasing evidence has shown that fecal microbiota transplantation (FMT) could be a promising treatment option for Crohn’s disease (CD). However, the frequency of FMT for CD treatment remains unclear. This study aimed to evaluate the optimal timing for administering the second course of FMT to maintain the long-term clinical effects from the first FMT for patients with CD. Sixty-nine patients with active CD who underwent FMT twice and benefited from the first FMT were enrolled in this study. Clinical response, stool microbiota, and urine metabolome of patients were assessed during the follow-up. The median time of maintaining clinical response to the first FMT in total 69 patients was 125 days (IQR, 82.5–225.5). The time of maintaining clinical response to the second FMT in 56 of 69 patients was 176.5 days (IQR, 98.5–280). The fecal microbiota composition of each patient post the first FMT was closer to that of his/her donor. Compared to that of the baseline, patients prior to the second course of FMT showed significant differences in urinary metabolic profiles characterized by increased indoxyl sulfate, 4-hydroxyphenylacetate, creatinine, dimethylamine, glycylproline, hippurate, and trimethylamine oxide (TMAO). This study demonstrated that patients with CD could be administered the second course of FMT less than 4 months after the first FMT for maintaining the clinical benefits from the first FMT. This was supported by the host–microbial metabolism changes in patients with active CD. Trial registration: ClinicalTrials.gov, NCT01793831. Registered 18 February 2013. https://clinicaltrials.gov/ct2/show/NCT01793831?term=NCT01793831&rank=1 Electronic supplementary material The online version of this article (10.1007/s00253-018-9447-x) contains supplementary material, which is available to authorized users.

Copper(II) complexes efficiently catalyze hydrogen peroxide to generate reactive oxygen species (ROS), which is the major reason for its significant anti-tumor activity. We synthesized three Cu(II) piperidylthiosemicarbazone complexes and examined their structures by X-ray single crystal diffraction. These Cu(II) complexes have significant apoptosis-promoting activity at nanomolar concentrations. The antitumor activity of these Cu(II) complexes is increased by more than 40-fold relative to that of the ligand. The binding experiment results demonstrated that the Cu(II) complexes interact with DNA with moderate binding affinity by in situ intercalation. Gel electrophoresis analysis indicated that DNA is degraded when the copper complex catalyzes hydrogen peroxide to produce reactive oxygen species (ROS). Apoptosis mechanism results showed that excessive ROS leads to mitochondrial membrane potential dissipation and promote the release of apoptotic factors from mitochondria.

Two types of α-N-heterocyclic piperidylthiosemicarbazone ligands and related Ga(III) complexes were synthesized. The structure of Ga4 and Ga5 were characterized by X-ray single crystal diffraction. We generated the related α-N-heterocycliperidinylthiosemicarbazone analogs to examine the effect of aldehydes or ketones in the Schiff base. The antitumor activity of both type ligands increased after coordination with gallium. Interestingly, the antitumor activity of gallium complexes containing pyridyl groups (first type ligands) is higher than that of pyrazine group-containing (second type ligands) complexes. Gallium complexes significantly depleted cellular iron, resulting in upregulation of transferrin receptor-1 and downregulation of ferritin. They also effectively activate the caspase family proteins (caspase-3/7/9), promote the release of cytochromes from the mitochondria, and ultimately lead to apoptosis.

A novel amphiphilic acid/light dual-cleavable diblock copolymer poly(e-caprolactone)-acetal-nitrobenzyl ester-poly(ethylene glycol) (PCL-PEG) was prepared via the ring-opening polymerization of e-caprolactone using 5-propargylether-2-nitrobenzyl alcohol as the initiator and subsequent “click” coupling reaction with azide-terminated poly(ethylene glycol) containing acetal group. Both light-cleavable o-nitrobenzyl methyl ester (ONB) and acid-labile acetal were used as the linkages in between the hydrophilic and hydrophobic polymer blocks. In aqueous solution, the copolymer self-assembled into the spherical polymeric nanoparticles, which were stable under physiological conditions and retained the anticancer drug doxorubicin (DOX) inside. Triggered by acid or UV irradiation, the DOX release rate was significantly enhanced, due to the correspondent degradation of acetal or ONB linkages under the stimulus. In addition, confocal laser scanning microscopy studies further demonstrated the DOX-loaded nanodrug could be efficiently taken up by HeLa cells and exhibited the enhanced DOX release into the cytoplasm upon UV irradiation. Furthermore, in vitro cytotoxicity study verified UV irradiation could improve the antitumor efficacy of the nanodrug against HeLa cells. Thus, this work provides a new method of the design of dual-responsive biodegradable polymers for drug delivery.

As one of the main sources of the air pollution, the NOx emission from combustion is difficult to avoid. In this research, a combustion method, named as Oxygen Diluted Partially Premixed and Oxygen Enriched Supplemental Combustion (ODPP/OESC) was proposed to reduce the NOx generation by adjusting the oxygen concentration. The relationships between the operating parameters were deduced. The effects of the ODPP/OESC on the NOx and CO emission were evaluated experimentally. Design of Experiments (DoE) was conducted to obtain the optimal operating parameters through the Response Surface Methodology (RSM). Further statistical analysis indicated that as the dominant operating parameter, the lower oxygen mole fraction of oxygen diluted air (Yod) resulted in lower NOx but higher CO emission. The Yod makes the most contribution to the NOx and CO emission, then the oxygen mole fraction of oxygen enriched air (Yoe) does, and the equivalence ratio of premixed gas (ERp) does the least. The regression analysis yielded two relationships between the NOx(CO), Yod, Yoe, and ERp. The optimal operating parameters were obtained by the RSM and verified experimentally. NOx and CO emission were 22.6 mg/m3 and 362 mg/m3 under the optimal condition, respectively. So the ODPP/OESC was promising and feasible for the low emission of the CH4/air combustion and the RSM can be used to control the combustion emissions.

Enzyme mimics have been developed for bioassay of nucleic acids, with some of them involving complicated labeling. Herein, we report a label-free bioassay for ultrasensitive electronic determination of microRNA at an ultralow concentration based on target-triggered long-range self-assembly DNA-based hybridization chain reaction (HCR) protocol coupled with bienzyme mimics synergistic catalysis strategy. In this work, a planar intercalation molecule, copper (II) complex, is applied for the first time as a small molecule enzyme mimic as well as intercalation molecule in microRNA biosensor for signal amplification. Fe3O4 nanozyme were used as a separate and enriched target under magnetic field, and also in combination with HCR protocol detected in 3,3',5,5'-tetramethylbenzidine+hydrogen peroxide (TMB+H2O2) system to improve the sensitivity of the biosensor. Under optimal conditions, these strategies present good electrochemical behaviors for the detection of microRNA with a wide range from 100 aM to 100 nM and at relatively low detection limit of 33 aM This remarkable sensitivity can make this proposed approach a promising scheme for development of next-generation microRNA sensors without the need of enzyme labeling or fluorophore labeling.

Carbon nitride has attracted extensive attention because of its promising properties and great application potential in photocatalysis, electrocatalysis, bioimaging and biomedicine. In this work, carbon nitride with a novel morphology, i.e., tetragonal carbon nitride hollow tube (TCNT), was in-situ synthesized by a molten salt method at 450 °C using melamine as the starting precursor. As-prepared TCNTs were 2–20 μm long and 50–2000 nm wide and possessed higher content of impurity nitrogen and larger specific surface area than conventional bulk g-C3N4 (B-CN). A possible salt-assisted self-assembly mechanism is believed to have dominated the formation of TCNTs. As-prepared TCNTs exhibited superior photocatalytic activities and adsorption performance for methylene blue and phenol degradation to B-CN, suggesting that they could be potentially used as a promising photocatalyst and adsorbent.

The MnO 2 -mullite-cordierite composite particle (MnO 2 -MCP) was prepared and firstly was applied as catalyst with sodium hypochlorite (NaOCl) as oxidant in heterogeneous Fenton-like system for methylene blue (MB) decolorization. The MnO 2 -MCP was characterized by XRD, SEM, EDS and BET analysis. The decolorization efficiencies of MB/MnO 2 -MCP, MB/NaClO, (MB after filtrating MnO 2 -MCP)/NaClO and MB/MnO 2 -MCP/NaClO were compared, which confirmed the interaction ability between MnO 2 -MCP and NaClO. After evaluating the role of adsorption of MB by MnO 2 -MCP, the catalytic oxidation effects of MnO 2 -MCP with NaClO on MB were exploited. The adsorption results showed that the new porous catalyst had certain adsorption capacity for MB and the adsorption fit best with Langmuir model. The central composite rotatable design (CCD) of response surface methodology (RSM) was used to design catalytic oxidation experiments of MB/MnO 2 -MCP/NaClO system, with influencing factors of catalyst dose, NaClO concentration, pH and initial MB concentration. The optimum conditions were 5.97 mM of NaClO, 37.9 g/L of catalyst dose, 5.74 of pH value and 100.71 mg/L of initial MB concentration, which could ensure nearly 100% MB decolorization. The effect of radical scavengers elucidated that superoxide anion (O 2 − ) was the main species to decolorize MB. Then the possible degradation mechanism and pathway of MB were proposed in this MnO 2 -MCP/NaClO system.

An ultrasensitive electrochemical detection method was developed to detect circulating tumor cells (CTCs) by using reduced graphene oxide/gold nanoparticles composites (rGO/AuNPs composites) as a support material with CuO nanozyme as a catalyst. MCF-7 circulating tumor cells were detected by an electrochemical cytosensor with effective surface recognition between specific mucin 1 protein (MUC-1) over-expressed on the MCF-7 cell membranes and MUC-1 aptamer. The CuO nanozyme is used as a signal-amplifying nanoprobe in an ultrasensitive electrochemical cytosensor to detect CTCs for the first time. Under the optimized experimental conditions, the proposed cytosensor exhibited significant analytical performance for the determination of MCF-7 circulating tumor cells. A wide detection range from 50 to 7 × 103 cells mL− 1 with a detection limit as low as 27 cells mL− 1 was reached on the condition of acceptable selectivity and reproducibility. Furthermore, the cytosensor can easily distinguish CTCs from the real serum sample due to the specific combination of MUC-1 and MUC-1 aptamer.

This study presents the role of the magnesium phenylmalonate (MgPA) in the thermal behavior, fluidity, and mechanical properties of Poly(L-lactic acid) (PLLA). The results from non-isothermal crystallization investigation showed that the presence of MgPA as a heterogeneous nucleating agent facilitated the crystallization of PLLA in cooling. Additionally, the non-isothermal crystallization behavior of PLLA/MgPA was affected significantly by MgPA concentration, the cooling rate, and the final melting temperature. Melting behavior of PLLA/MgPA under different testing conditions further confirmed the crystallization accelerating effect of MgPA for PLLA, and the double melting peaks of PLLA/MgPA system mainly assigned to the melting-recrystallization mechanism. A decrease of the onset decomposition temperature indicated that the incorporation of MgPA reduced the thermal stability of PLLA, but the effect of MgPA on the thermal decomposition profile of PLLA is negligible. Compared to the primary PLLA, the addition of MgPA could improve significantly the fluidity of the PLLA, and the fluidity became better with increasing of MgPA concentration in PLLA matrix. MgPA of 0.2 wt.% to 2 wt.% could make the tensile strength of PLLA increase, however, a continuous drop in elongation at break was also observed.DOI: http://dx.doi.org/10.5755/j01.ms.24.1.17947

Novel Fe3C nanoparticles encapsulated with nitrogen-doped graphitic shells were synthesized by floating catalytic pyrolysis. Due to the short synthesis time and controllable pyrolytic temperature, the diameters of Fe3C core nanoparticles ranged from 5 to 15 nm (Fe3C@NGS900 prepared at 900 °C) and the average thickness of N-doped graphitic shells was ∼1.2 nm, leading to their high electrochemical performance: specific capacity of 1300 mA h g−1 at current density 0.2 A g−1, outstanding rate capability of 939 mA h g−1 at 3 A g−1, improved initial coulombic efficiency (Fe3C@NGS900: 72.1% vs. NGS900 (pure graphitic shells): 52%) for lithium ion batteries (LIBs), and impressive long-term cycle performance (1399 mA h g−1 maintained at 3 A g−1 after 500 cycles for LIBs; 214 mA h g−1 maintained at 1 A g−1 after 500 cycles for sodium ion batteries).