Search

Graphite is a widely used oxygen impurity-removing additive and a property-tuning second phase for diboride and carbide-based ultrahigh temperature ceramics (UHTCs). In recent years, high-entropy diboride (HEB) ceramics have attracted much attention for the development of better UHTCs. However, oxide impurity generally inhibits their densification and harms their properties. Here, (Ti 0.2 Zr 0.2 Hf 0.2 Nb 0.2 Ta 0.2)B 2 ceramics added with different contents of graphite (HEB- x C, x = 0, 1, 2.5, 5, 10, 20 vol%) were prepared by spark plasma sintering. It was found that the added graphite acted as an oxygen-removing agent and the oxide impurity phase t -(Zr, Hf)O 2 was converted to the (Hf, Ta)C-based solid solution carbide. With the increase in graphite content, the relative density increased from 89.4% for HEB-0 C to 100% for HEB-10 C. Based on the evaluated properties of the prepared specimens, including Young's modulus, hardness, toughness, and thermal conductivity, the added graphite with an optimized content is important for a given started powder and processing to achieve good and balanced material properties. [ABSTRACT FROM AUTHOR]

[Display omitted] • Na 3.4 Mn 0.7 Ti 0.3 Cr(PO 4) 3 /C cathode material is prepared by a simple sol–gel method. • Ti substitution shortens the average bond length of TM-O. • Ti substitution can suppress the Jahn-Teller effect of Na 4 MnCrPO 4 cathode material. • Ti substitution reduces the R ct of cathode and suppress interface side reactions. The sodium superionic conductor Na 4 MnCr(PO 4) 3 gains increasing attention owing to its three-dimensional structure and the three-electron reaction. However, rapid structure degradation during cycling is the major challenge for its practical application. Herein, Ti4+ is utilized to replace a portion of Mn2+ in Na 4 MnCr(PO 4) 3. The low redox voltage and d 0 electronic configuration of the Ti4+ ions are helpful to suppress the structure alteration and improve electronic conduction. Consequently, the as-prepared Na 3.4 Mn 0.7 Ti 0.3 Cr(PO 4) 3 /C cathode exhibits a remarkable good 91.0% capacity retention after 500 cycles at 10C rate, with exceptional rate capacities of 99.5 mAh g−1 and 81.0 mAh g−1 at 5C and 10C rate, respectively. Furthermore, based on ≈2.86-electron reactions involving Mn2+/Mn3+ (3.5 V), Mn3+/Mn4+ (4.1 V), Cr3+/Cr4+ (4.3 V), and Ti3+/Ti4+ (2.1 V), the material can provide an energy density of approximately 541.6 Wh kg−1, slightly surpassing that of Na 4 MnCr(PO 4) 3. Ex-situ XRD investigation further elucidates that throughout the entire charge–discharge process, the Ti-substituted material experiences highly reversible solid-solution and two-phase reactions. Additionally, Ti substitution can greatly promote the interfacial charge transfer of the material and suppress the decomposition of the electrolyte during cycling. This work might open a new insight for designing sodium-ion battery cathode materials with good cycling stability and high energy density. [ABSTRACT FROM AUTHOR]

Two internal solitary waves (ISWs) with very long fronts observed by synthetic aperture radar (SAR) images in the northern South China Sea (NSCS) are comparatively analyzed based on oceanic reanalysis data and the Korteweg–de Vries (KdV) theory. The differences in the environmental parameters, wave half-width, and amplitude of the two ISW fronts in the two distinct oceanic environments are studied. In the presence of a weak westward surface current of approximately 0.05 m/s, the values of the linear wave speed increase by up to 0.056 m/s, and the retrieved ISW amplitudes decrease by up to 14 m. On the contrary, for another background oceanic environment considering a relatively strong eastward surface current of approximately 0.2 m/s, there are decreases of up to 0.17 m/s in the linear wave speed and increases of up to 32 m in the retrieved amplitudes. However, the results retrieved from both the SAR observations commonly show that the ISW amplitudes along the fronts reach their maximums at roughly 21°N and decrease toward the southern and northern sides, in spite of their distinct background environments. [ABSTRACT FROM AUTHOR]

A subwavelength seismic metamaterial (SM) consisting of a three-component SM plate (SMP) and a half space is proposed to attenuate ultra-low frequency seismic surface waves. The design concept and models are verified first by lab-scale experiments on the SM consisting of a two-component SMP and a half space. Then, we calculate the band structures of one-dimensional and two-dimensional subwavelength SMs and evaluate their ability to attenuate Rayleigh waves. A wide ultra-low frequency bandgap can be found, and the Rayleigh waves are deflected by the subwavelength SM and converted into bulk waves in the frequency range of this bandgap. When the number of unit cells of the subwavelength SM is sufficient, the transmission distance and deflection angle of the Rayleigh waves are constant at the same frequency. This discovery is expected to open up the possibility of pragmatic seismic protection for large nuclear power plants, ancient buildings, and metropolitan areas. [ABSTRACT FROM AUTHOR]

Background: The composition of glutenin protein significantly affects protein–starch interactions and starch digestion characteristics in wheat dough matrices. To elucidate the effects of high molecular weight glutenin subunits at the Glu‐B1 locus on dough processing quality, the detailed structural changes of protein, starch, and their complexes were compared in Mixolab dough samples of two near isogenic lines 7 + 8 and 7 + 9. Results: The results showed that the degree of protein aggregation increased continuously during dough processing, as did the destruction and rearrangement of the gluten network. Compared to 7 + 8, the stronger and more stable protein network formed in 7 + 9 dough induced intensive interactions between protein and starch, primarily through hydrogen bonds and isomeric glycosidic bonds. In 7 + 9 dough, the more compact and extensive protein–starch network significantly inhibited starch gelatinization during dough pasting, while during the dough cooling stage [from C4 (82.8 °C) to C5 (52.8 °C)], more protein–starch complexes composed of monomeric proteins and short‐chain starch were generated, which remarkably inhibited starch retrogradation. All protein–starch interactions in the 7 + 9 dough improved the starch digestion resistance, as reflected by the high content of resistant starch. Conclusion: The more extensive and intensive protein–starch interactions in the 7 + 9 dough inhibited the gelatinization and enzymatic hydrolysis of starch, thereby producing more slowly digestible starch and resistant starch. These findings demonstrate the feasibility of optimizing the texture and digestibility of wheat‐based food products by regulating the behavior and interactions of proteins and starch during dough processing. © 2022 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Polymer-containing oily sludge (PCOS) has caused tremendous hazards with the broad application of polymer flooding technology. Traditional methods cannot meet the treatment demand due to the high-water content of PCOS. In this work, the degradation of PCOS in sub-/supercritical water is studied to explore an appropriate treatment method. The influence of residence time (15–90 min), temperature (340–700°C), catalysts (sulfates, carbonates, and alkalis), and co-solvents (methanol-water and ethanol-water) on the distribution of end products is studied in details. Results show that PCOS is hardly gasified under the subcritical conditions and the increase in residence time and temperature has positive effects on the phase conversion. The conversion rate reaches 81.77% at 60 min, 340°C, compared to 67.09% at 15 min. Supercritical water shows a great solubility for PCOS, and no solid residues are detected at supercritical conditions (400–700°C, 23 MPa). Organic matter in liquid phase is classified into nine types, and the increase in temperature greatly changes its composition. The relative proportion of ketones reaches more than 50% of the organic matter in liquid at 400°C. Ketones are proven to be the main source of CO2 and disappear at above 500°C. Moreover, the migration of elements (carbon and nitrogen) is comprehensively studied. [ABSTRACT FROM AUTHOR]

Purpose: The purpose of this paper on the one hand is to reduce the sintering temperature, shorten the sintering time and improve the electrical properties of the sample through the two-step flash sintering method and on the other hand is to study the effect of electric field on the phase structure, microstructure and electrical properties of the flash sintering sample. Design/methodology/approach: In this paper, (Mg1/3Ta2/3)0.01Ti0.99O2 giant dielectric ceramics were prepared by conventional sintering and two-step flash sintering, respectively. Further, the effect of electric field (600–750 V/cm) on the electrical properties of (Mg1/3Ta2/3)0.01Ti0.99O2 giant dielectric ceramics was studied. Findings: The results show that compared with the conventional sintering, the sintering temperature of the two-step flash sintering can be reduced by 200°C and the sintering time can be shortened by 12 times. All sintered samples were single rutile TiO2 structure. Compared with conventional sintering, two-step flash sintering samples have finer grain size. The two-step flash sintered sample has similar dielectric properties to the conventional sintered sample. The dielectric constant of flash sintered samples decreases with the increase of electric field. When the electric field is 700 V/cm, the ceramic sample has the optimal dielectric properties, where the dielectric constant is approximately 5.5 × 103 and the dielectric loss is about 0.18 at 1 kHz. Impedance spectroscopy analysis shows that the excellent dielectric properties are attributed to the internal barrier layer capacitance model. Originality/value: This paper not only provides a new method for the preparation of co-doped TiO2 giant dielectric ceramics but also has great potential in greatly improving efficiency and saving energy. [ABSTRACT FROM AUTHOR]

It is challenging to establish single metal atoms with a uniform coordination environment at targeted sites of a zeolite. In this study, single platinum atoms were selectively encaged in the six‐membered rings of sodalite (SOD) cages within Y zeolite using a template‐guiding strategy. During the in situ synthesis process, template molecules were designed to occupy supercages and thereby force coordinated platinum species into SOD cages. Subsequent control of the post‐treatment conditions yielded the Y zeolite with selectively encaged single platinum atoms, denoted Pt@Y‐SOD. The Pt@Y‐SOD catalyst had good stability and excellent catalytic selectivity in the semihydrogenation reaction, and it exhibited interesting thiophene and carbon monoxide resistance in this transformation because interactions with these poisons are weakened by the configuration of the encaged single platinum atoms. [ABSTRACT FROM AUTHOR]

It is challenging to establish single metal atoms with a uniform coordination environment at targeted sites of a zeolite. In this study, single platinum atoms were selectively encaged in the six‐membered rings of sodalite (SOD) cages within Y zeolite using a template‐guiding strategy. During the in situ synthesis process, template molecules were designed to occupy supercages and thereby force coordinated platinum species into SOD cages. Subsequent control of the post‐treatment conditions yielded the Y zeolite with selectively encaged single platinum atoms, denoted Pt@Y‐SOD. The Pt@Y‐SOD catalyst had good stability and excellent catalytic selectivity in the semihydrogenation reaction, and it exhibited interesting thiophene and carbon monoxide resistance in this transformation because interactions with these poisons are weakened by the configuration of the encaged single platinum atoms. [ABSTRACT FROM AUTHOR]

The precise control of complex quantum mechanical systems can unlock applications ranging from quantum simulation to quantum computation. Controlling strongly interacting many-body systems often relies on Floquet Hamiltonian engineering that is achieved by fast switching between Hamiltonian primitives via external control. For example, in our solid-state NMR system, we perform quantum simulation by modulating the natural Hamiltonian with control pulses. As the Floquet heating errors scale with the interpulse delay, δ t , it is favorable to keep δ t as short as possible, forcing our control pulses to be short duration and high power. Additionally, high-power pulses help to minimize undesirable evolution from occurring during the duration of the pulse. However, such pulses introduce an appreciable phase-transient control error, a form of unitary error. In this work, we detail our ability to diagnose the error, calibrate its magnitude, and correct it for π / 2 -pulses of arbitrary phase. We demonstrate the improvements gained by correcting for the phase transient error, using a method which we call the "frame-change technique", in a variety of experimental settings of interest. Given that the correction mechanism adds no real control overhead, we recommend that any resonance probe be checked for these phase transient control errors, and correct them using the frame-change technique. [Display omitted] • High-power pulses are vital components of high-fidelity quantum simulation. • Phase-transient errors can be quickly calibrated with experiments on nuclear spins. • We introduce a technique to analytically correct the phase-transient error. • The frame-change technique introduces no additional control overhead. • We demonstrate the frame-change corrected improvements experimentally. [ABSTRACT FROM AUTHOR]

In the preparation process for advanced ceramics, how to reduce the sintering temperature, shorten the processing time and refine grains is the key to obtaining high-performance ceramic materials. The flash sintering (FS) provides an effective method to solve this issue. Here, (Zr + Ta) co-doped TiO 2 colossal permittivity ceramics were successfully fabricated by conventional sintering (CS) and flash sintering under electric fields from 500 V/cm to 800 V/cm. The flash behavior, sintered crystal structure and microstructure, dielectric properties, and varistor characteristics were systematically investigated. The effects of the applied electric fields on the above behaviors were discussed. The results show that flash sintering can reduce the sintering temperature by 200 °C, decrease the processing time by 10 times and reduce grain sizes in TiO 2 ceramics. All sintered samples were single rutile structures. Flash sintering led to similar electrical properties to conventional sintering. In the flash-sintered samples, with increasing the electric field, the permittivity of co-doped TiO 2 ceramics increased at a frequency of 103–104 Hz. The flash-sintered sample under an electric field of 800 V/cm possessed the best comprehensive properties, a dielectric permittivity of >105, a dielectric loss of ∼0.77 at 103 Hz, and a nonlinear coefficient of 5.2. [ABSTRACT FROM AUTHOR]

Design of heterogeneous catalyst to achieve efficient conversion of biomass to high added-value chemicals is still very attractive. Herein, taking industrially important selective hydrogenation of furfural to furfuryl alcohol as an example, the designed amorphized HA zeolite encapsulation of platinum clusters (denoted as Pt@HA) exhibited excellent catalytic selectivity at totally conversion of the reactant furfural, along with good reusability and poison resistance ability. The selected amorphized HA zeolite with very small pore size constrained the reactant furfural to be reacted through hydrogen spillover process at zeolite surface, instead of to be adsorbed and activated onto Pt surface. Resulting from the stronger interaction between nucleophilic oxygen atom of aldehyde group and acid site at HA zeolite surface than that of furan ring group, furfural preferred to adsorb onto Pt@HA surface with the end of aldehyde group rather than the end of furan ring group, thus facilitating the spilled H atom to react with aldehyde group to give desired furfuryl alcohol product exclusively. [Display omitted] • Pt@HA exhibited remarkable catalytic property in hydrogenation of furfural to furfuryl alcohol via hydrogen spillover. • Spillover process disfavored activation of aldehyde group and furan ring simultaneously in one furfural molecule. • Acid sites on HA zeolite surface promoted adsorption of aldehyde group to facilitate its hydrogenation process. [ABSTRACT FROM AUTHOR]

In the offshore petroleum industry, polymer-containing oily sludge (PCOS) hinders oil extraction and causes tremendous hazards to the marine ecological environment. In this paper, an effective pretreatment method is proposed to break the adhesive structure of PCOS, and the experiments of supercritical water gasification are carried out under the influencing factors including residence time (5–30 min) and temperature (400–750 °C) in batch reactors. The increase of time and temperature all show great promoting effects on gas production. Polycyclic aromatic hydrocarbons, including naphthalene and phenanthrene, are considered as the main obstacles for a complete gasification. Carbon gasification efficiency (CE) reaches maximum of 95.82% at 750 °C, 23 MPa for 30 min, while naphthalene makes up 70% of the organic compounds in residual liquid products. The highest hydrogen yield of 19.79 (mol H 2 /kg of PCOS) is observed in 750 °C for 25 min. A simplified reaction pathway is presented to describe the gaseous products (H 2 , CO, CO 2 , CH 4). Two intermediates are defined for describing the reaction process bases on the exhaustive study on organic matters in residual liquid products. The results show that the calculated data and the experimental data have a high degree of fit and tar formation reaction is finished within 10 min. [Display omitted] • Utilization of polymer-containing oily sludge via supercritical water gasification. • Optimal gasification condition is obtained. • Reaction mechanism of gasification is discussed. • Tar formation reaction can be finished within 10 min in quartz tubes. [ABSTRACT FROM AUTHOR]

Metronidazole-induced optic neuropathy is a rare complication. Most patients have excellent visual recovery. In this study, we report a patient who presented with a sudden onset of severe visual loss after a 1-week course of metronidazole. Myelitis developed simultaneously. The vision and the accompanying neurological deficiency of the patient did not improve even after metronidazole was discontinued immediately and various treatments were given. [ABSTRACT FROM AUTHOR]

With the development of autonomous driving, ensuring pedestrian safety has become a hot research topic. The traditional pedestrian crossing behavior research mostly track and predict pedestrian crossing from the view of vehicles, but do not have in-depth research on the impact of other elements in the traffic scene. This paper proposes a method for analyzing pedestrian crossing behavior based on roadside equipment for specific road sections. First, a pedestrian awareness-based social force model (PASFM) is proposed by introducing the factors that influence pedestrian crossing decisions in traffic scenarios into the social force model (SFM), including zebra crossings, fellow walkers and vehicles. To explore the psychological state of vehicles and pedestrians when they interact, evolutionary game theory is used to simulate the psychological characteristics of pedestrians when they encounter vehicles, and then reflect in the changes of the desired speed. Then Centralized Unscented Kalman Filter (CUKF) is proposed to complete the whole process of tracking and predicting the motion state of pedestrian crossing behavior, which uses PASFM as its prediction process. Finally, simulations and experiments are designed to show the effectiveness of our methods. Results show that the proposed method performs better during pedestrian tracking and can predict their crossing behavior to a certain extent. [ABSTRACT FROM AUTHOR]

In this work, we propose DDFusion, a novel multi-exposure image fusion network. DDFusion addresses the limitations of existing methods by effectively recovering details near extremely bright regions and learning associations between non-contiguous regions. To achieve this, our network incorporates a dense pyramidal (DensePy) convolution block in the encoder for multi-scale feature extraction, and a de-correlation fusion (DF) block for enabling structurally coherent and edge-preserving multi-scale feature fusion. It facilitates a smoother transition from highlighted areas to adjacent regions in the fused image. Experimental results demonstrate the superiority of DDFusion over state-of-the-art deep methods in terms of both visual quality and quantitative evaluation. Moreover, DDFusion achieves stronger multi-scale feature extraction capability with smaller computational complexity. • The proposed dense pyramidal convolution block combines PyConv and dense connections, which forms a multi-scale feature expression with more continuous in scale and complementary in content. • The designed DF block contains FastDeconv and an attention module, which enhances high-frequency edge details and fuses multi-scale structural features smoothly, enabling structurally coherent and edge-preserving multi-scale feature fusion. • The proposed DDFusion integrates dense pyramidal convolution and DF blocks, facilitating a smoother transition between highlighted areas and adjacent regions and reducing the influence of uneven illumination in recovering details. [ABSTRACT FROM AUTHOR]

Green tea, superfine green tea powder (SGTP), and tea extract were prepared to determine their chemical components and antioxidant activity. The nutrition and aroma challenges of green tea during traditional extract technique and superfine grinding were profiled in this study. The traditional extract technique took advantage over superfine grinding in L‐theanine and glutamic acid (Glu) preservation, but not in other 16 essential amino acids. SGTP preserved a maximum of elements from green tea, whereas tea extract greatly changed the elements ratio. Tea extract contained higher VB2 and VC contents and doubled the tea polyphenol (TP) content in comparison with green tea and SGTP. Additionally, tea extract contained more favorable aroma compounds and maintained stronger antioxidant activity in comparison with green tea and SGTP. This study profiled an important basis for the comprehensive utilization of green tea resources by consumers and manufacturers. [ABSTRACT FROM AUTHOR]

Programming intelligent DNA nanocarriers for the targeted transport of molecular payloads in living cells has attracted extensive attention. In vivo activation of these nanocarriers usually relies on external light irradiation. An interest is emerging in the automatic recognition of intracellular surroundings by nanocarriers and their in situ activation under the control of programmed DNA‐computation circuits. Herein, we report the integration of DNA circuits with framework nucleic acid (FNA) nanocarriers that consist of a truncated square pyramid (TSP) cage and a built‐in duplex cargo containing an antisense strand of the target mRNA. An i‐motif and ATP aptamer embedded in the TSP are employed as logic‐controlling units to respond to H+ and ATP inside cellular compartments, triggering the release of the sensing element for fluorescent mRNA imaging. Logic‐controlled FNA devices could be used to target drug delivery, enabling precise disease treatment. [ABSTRACT FROM AUTHOR]

Programming intelligent DNA nanocarriers for the targeted transport of molecular payloads in living cells has attracted extensive attention. In vivo activation of these nanocarriers usually relies on external light irradiation. An interest is emerging in the automatic recognition of intracellular surroundings by nanocarriers and their in situ activation under the control of programmed DNA‐computation circuits. Herein, we report the integration of DNA circuits with framework nucleic acid (FNA) nanocarriers that consist of a truncated square pyramid (TSP) cage and a built‐in duplex cargo containing an antisense strand of the target mRNA. An i‐motif and ATP aptamer embedded in the TSP are employed as logic‐controlling units to respond to H+ and ATP inside cellular compartments, triggering the release of the sensing element for fluorescent mRNA imaging. Logic‐controlled FNA devices could be used to target drug delivery, enabling precise disease treatment. [ABSTRACT FROM AUTHOR]

Aims: Ventricular arrhythmias (VAs) originating from the para‐Hisian region represent a challenging location. The long‐term success rate of catheter ablation above the septal leaflet of the tricuspid valve is not ideal. This study aimed to investigate the safety and efficacy of catheter ablation for para‐Hisian VAs via a direct approach under the septal valve with reversed C‐curve technique. Methods and Results: Twenty‐five consecutive patients with para‐Hisian VAs were included. Systematic mapping was performed in the right ventricle septum, including both the regions above and under the septal valve. Radiofrequency (RF) ablation was preferentially performed under the valve with reversed C‐curve technique in all patients. If the ablation failed under the valve, it was then performed above the valve and even in aortic sinus cusps. The earliest ventricular activation preceding surface QRS (V‐QRS) under the valve was significantly larger than that above the valve (34.8 ± 5.3 vs 27.8 ± 5.7 ms, P < .01). RF ablation under the valve with reversed C‐curve technique achieved acute success in 22 of 25 (88%) patients. Junctional rhythm developed during ablation in 3 of 25 (12%) patients and no atrioventricular block occurred. In the remaining three patients, RF application above the valve failed to eliminate the VAs and one of them achieved successful ablation in the right coronary cusp. During a mean follow‐up of 17.8 ± 9.4 months, no patients presented with VAs recurrence and no postprocedure complications occurred. Conclusions: Catheter ablation under the valve with reversed C‐curve technique shows to be effective and safe for para‐Hisian VAs. [ABSTRACT FROM AUTHOR]

• A fractal model for the soil–water characteristic curve of Hunan clay was derived. • A fractal model for nonlinear seepage of saturated clay was established. • The model allows for easy computation and prediction of continuous permeation. • The prediction remains accurate even in soil with high dry density. It is crucial to investigate nonlinear seepage phenomena in low-permeability soils. Currently, empirical formulas account for the majority of nonlinear seepage model formulations. Some theoretical prediction models have been proposed; however, they tend to be computationally complex, and their predictive performance must be enhanced. Considered an indirect indicator, the soil–water characteristic curve reflects the permeation channels of soil pores of varying diameters. A nonlinear seepage model for saturated clay has been devised, taking into account the initial hydraulic gradient of microscopic seepage channels. This paper derives and solves the fractal dimension of the soil–water characteristic curve fractal model and establishes a new nonlinear seepage fractal model for saturated clay under various hydraulic gradients. The new seepage fractal model proposed in this paper is used to predict the seepage velocity of saturated Hunan clay under various hydraulic gradients and is compared to the results of its nonlinear seepage test. Overall, the results indicate that the predicted values of the seepage fractal model presented in this paper closely match the experimental values, and the accuracy of the prediction of the seepage velocity of saturated clay with a higher dry density exceeds that of present theoretical models. [ABSTRACT FROM AUTHOR]

Abstract To develop a novel lignin-based highly efficient nitrogen fertilizer, the amination of the biorefinery technical lignin was conducted by Mannich reaction synergy with phenolation pretreatment. Subsequently, the structural transformations of lignin samples and the reaction mechanism were investigated in detail. The soil column leaching experiment was also performed to research the nitrogen release behavior of aminated lignin in soil. The results indicated that the amounts of active sites in lignin were significantly increased to 8.26 mmol/g from the original 2.91 mmol/g by phenolation. In addition, the Mannich reaction was highly selective for occurring at ortho - and para -positions of phenolic hydroxyl groups in the phenolated lignin, in which the latter was favored. Moreover, the nitrogen content in the aminated lignin was highly depended on the types of amination reagent instead of the proportion of reactants in this study. Under an optimal condition, aminated lignin with a high nitrogen content (10.13%) and low C/N ratio (6.08) could be obtained. Besides, it was especially noteworthy that the prepared APL in this study has a favorable nitrogen release behavior in soil. Thus, it is believed that these aminated lignin derivatives could be used for the preparation of various lignin-based highly efficient nitrogen fertilizer. Highlights • The chemical reactivity of lignin was significantly improved by phenolation. • The nitrogen content of APL was highly depended on the types of amination reagent. • Ethanediamine is regarded as the most favorable among these selected amination reagents. • An optimum chemosynthesis condition of high N-containing APL was obtained. • A new approach was developed to prepare lignin-based highly efficient fertilizer. [ABSTRACT FROM AUTHOR]

In nature, the formation of spider silk fibers begins with dimerizing the pH‐sensitive N‐terminal domains of silk proteins (spidroins) upon lowering pH, and provides a natural masterpiece for programmable assembly. Inspired by the similarity of pH‐dependent dimerization behaviors, introduced here is an i‐motif‐guided model to mimic the initial step of spidroin assembly at the subcellular level. A framework nucleic acid (FNA) nanoplatform is designed using two tetrahedral DNA nanostructures (TDNs) with different branched vertexes carrying a bimolecular i‐motif and a split ATP aptamer. Once TDNs enter acidic lysosomes within living cells, they assemble into a heterodimeric architecture, thereby enabling the formation of a larger‐size framework and meanwhile subcellular imaging in response to endogenous ATP, which can be dynamically manipulated by adjusting intracellular pH and ATP levels with external drug stimuli. Itsy bitsy spider: To mimic the self‐assembly manner of spider silk proteins, a reconfigurable bioinspired framework nucleic acid nanoplatform has been designed and is dynamically regulated within living cells for lysosome imaging. The dimerization of the DNA structures is pH‐dependent and they enable subcellular imaging in response to endogenous ATP. [ABSTRACT FROM AUTHOR]

In nature, the formation of spider silk fibers begins with dimerizing the pH‐sensitive N‐terminal domains of silk proteins (spidroins) upon lowering pH, and provides a natural masterpiece for programmable assembly. Inspired by the similarity of pH‐dependent dimerization behaviors, introduced here is an i‐motif‐guided model to mimic the initial step of spidroin assembly at the subcellular level. A framework nucleic acid (FNA) nanoplatform is designed using two tetrahedral DNA nanostructures (TDNs) with different branched vertexes carrying a bimolecular i‐motif and a split ATP aptamer. Once TDNs enter acidic lysosomes within living cells, they assemble into a heterodimeric architecture, thereby enabling the formation of a larger‐size framework and meanwhile subcellular imaging in response to endogenous ATP, which can be dynamically manipulated by adjusting intracellular pH and ATP levels with external drug stimuli. [ABSTRACT FROM AUTHOR]

Highlights • The aluminium foam sandwich was fabricated using friction stir welding. • No undesirable interface reaction existed among the face sheets and the foam core. • AFS prepared through FSW possessed high flexural strength and impact resistance. • The AFS possessed good sound absorption and insulation performance. Abstract The aluminium foam sandwich (AFS), prepared through the traditional adhesive or brazing methods, usually exhibits a low flexural strength due to the poor combination among the face sheets and the aluminium foam core. In this work, a new method, named friction stir welding (FSW), was utilized to fabricate AFS. The results demonstrated that the joining of the face sheets and aluminium foam was achieved through the plasticized metal flow. In addition, the AFS prepared through FSW possessed high flexural strength and impact resistance, as well as good sound absorption and reduction performance. This demonstrated that the FSW was a good method to prepare AFS. [ABSTRACT FROM AUTHOR]

Graphical abstract Abstract Spontaneous symmetry breaking has revolutionized the understanding in numerous fields of modern physics. Here, we theoretically demonstrate the spontaneous time-reversal symmetry breaking in a cavity quantum electrodynamics system in which an atomic ensemble interacts coherently with a single resonant cavity mode. The interacting system can be effectively described by two coupled oscillators with positive and negative mass, when the two-level atoms are prepared in their excited states. The occurrence of symmetry breaking is controlled by the atomic detuning and the coupling to the cavity mode, which naturally divides the parameter space into the symmetry broken and symmetry unbroken phases. The two phases are separated by a spectral singularity, a so-called exceptional point, where the eigenstates of the Hamiltonian coalesce. When encircling the singularity in the parameter space, the quasi-adiabatic dynamics shows chiral mode switching which enables topological manipulation of quantum states. [ABSTRACT FROM AUTHOR]

We report a new signal readout mechanism for DNA molecular sensing devices using ligand-free fluorogenic G-quadruplexes in which the propeller-like loops are distinguished from the diagonal and lateral loops with incorporated 2-aminopurine (2-AP, a fluorescent analogue of adenine). We study the fluorescence behavior of looped-out 2-AP in duplexes and G-quadruplexes and demonstrate that it shows better fluorescence properties in shorter loops. In particular, 2-AP in the propeller-like loops of parallel or hybrid G-quadruplexes displays a perfect fluorescence emission whereas that in the diagonal and lateral loops does not. This loop-environment-sensitive feature allows 2-AP to probe the propeller-like loops of G-quadruplexes, illustrated by an ion-tuned allosteric G-quadruplex FG9A and a (3 + 1) hybrid human telomeric DNA. In the presence of K+, FG9A folds into a parallel structure where 2-AP is in the propeller-like loops and shows a high fluorescence signal, which can probe K+ concentrations down to 25 μM. Upon addition of Pb2+, the folded FG9A converts into an antiparallel structure which is revealed by a sharp decrease in 2-AP fluorescence, which can easily be reset with EDTA. This process is utilized to reversibly sense Pb2+ with a detection limit of 100 nM. Furthermore, its ability to probe the propeller-like loops may allow 2-AP to identify the folding topologies of unknown G-quadruplexes in human gene regions. [ABSTRACT FROM AUTHOR]

The article presents a case study of a 44-year-old male patient with repeated syncope for 5 years referred to our hospital. An electrophysiological study was performed. In addition, increasing the output from the proximal CS region may alter the atrial inputs by penetrating the AV node at more than one input. This phenomenon of treatment can be explained as vagal response caused by adjacent vagus ganglion capture.

A logic circuit controlled multi-responsive sensing platform built on a three-way DNA junction (TWJ) is reported. It enabled the construction of novel fluorescent sensing platforms responsive to any target out of HIV gene, ATP and pH value, and furthermore were logically regulated by two other targets and then behaved as different logic circuits, which consist of two tandem AND gates or cascaded NAND and INH gates by varying the positions of the fluorescent tags. [ABSTRACT FROM AUTHOR]

Emergence of antibiotic-resistant bacteria constitutes an increasing threat to human health. For example, treatment options for Staphylococcus aureus infections is declining with the worldwide spreading of highly virulent community-associated methicillin-resistant S. aureus (CA-MRSA) strains. Anti-virulence therapy has been proposed as an alternative treatment strategy, as it typically involves inhibition of expression of virulence factors rather than direct bacterial killing, thereby attenuating the risk of resistance development. An intriguing target is the agr quorum-sensing system, which is a major inducer of virulence in CA-MRSA upon activation by agr -encoded staphylococcal autoinducing peptides (AIPs). In the present work a previously identified lactam hybrid analogue based on the marine depsipeptide solonamide B and the general structure of AIPs was investigated with respect to structure–function relationships. An array of 27 analogues exploring expansion of ring size, type of side chain, amino acid substitutions, and stereochemistry was designed and tested for AgrC-inhibitory activity. Interestingly, it was found that an analogue derived from the mirror image of the original hit proved to be the hitherto most efficient AgrC inhibitor resembling solonamide B in amino acid sequence. This and closely related compounds were 20- to 40-fold more potent in AgrC inhibition than the starting hit compound. [ABSTRACT FROM AUTHOR]

A variety of nucleic acid amplification techniques have been integrated into different detection methods to promote the development of sensitive and convenient analysis of nucleic acids. However, it is still in urgent need to develop amplified nucleic acid biosensors for the analysis of susceptible gene and even distinguishing single-base mismatched DNA in complex biological samples. Benefiting from the achieved detection strategies, here we boost isothermal nucleic acid amplification by resorting to enzyme amplification, and combine this two-stage amplification method with surface-enhanced Raman spectroscopy (SERS) to develop a signal-on nucleic acid detection platform. Due to the high cleavage efficiency of Exonuclease III (Exo III), a large amount of trigger DNA are produced to initiate multiple hybridization chain reaction circles. The product structure tagged with Tamra is then anchored onto the plasmonic SERS substrate and meanwhile enriched. It is demonstrated that this detection platform is sensitive toward the myocardial infarction disease related gene. A detection limit of 1 fM for the gene analysis in a linear relationship in the wide range from 1 fM to 10 nM is achieved, better than most of previous counterparts. Meanwhile, our developed detection platform exhibits a high selectivity for the target gene over mismatched analogues. Our strategy provides a robust tool for signal amplification of gene detection even in blood samples. [ABSTRACT FROM AUTHOR]

We report several DNA nanodevices monitored with fluorogenic looped-out 2-aminopurine. It is found that looped-out 2-AP, an analogue of adenine, in split parallel G-quadruplexes, triplexes and duplexes always shows much higher fluorescence intensity than that in single- or double-stranded DNAs, due to the weaker quenching effects derived from the reduced base stacking environments. Taking advantage of these traits, we introduce a new strategy to monitor the behaviours of DNA nanodevices via the fluorescence signal output by utilizing changes in the base stacking environment of 2-AP. As proof-of-principle experiments, two nanoplatforms for detecting disease genes, as well as a triplex nanoswitch, are constructed and monitored by fluorogenic looped-out 2-AP, illustrating that fluorogenic looped-out 2-AP holds great promise for reading the behaviours of diverse DNA nanodevices. Compared with conventional fluorescence labelling, looped-out 2-AP as a reporter shows good photostability and can be quenched by base-pairing, thereby providing an efficient quencher-free methodology for monitoring DNA nanodevices. [ABSTRACT FROM AUTHOR]

Abstract: Current prognostic signatures need to be improved in identifying high‐risk patients of gastric cancer (GC). Thus, we aimed to develop a reliable prognostic signature that could assess the prognosis risk in GC patients. Two microarray datasets of GSE662254 (n = 300, training set) and GSE15459 (n = 192, test set) were included into analysis. Prognostic genes were screened to construct prognosis‐related gene pairs (PRGPs). Then, a penalized Cox proportional hazards regression model identified seven PRGPs, which constructed a prognostic signature and divided patients into high‐ and low‐risk groups according to the signature score. High‐risk patients showed a poorer prognosis than low‐risk patients in both the training set (hazard ratios [HR]: 6.086, 95% confidence interval [CI]: 4.341–8.533) and test set (1.773 [1.107–2.840]). The PRGPs signature also achieved a higher predictive accuracy (concordance index [C‐index]: 0.872, 95% CI: 0.846–0.897) than two existing molecular signatures (0.706 [0.667–0.744] for a 11‐gene signature and 0.684 [0.642–0.726] for a 24‐lncRNA signature) and TNM stage (0.764 [0.715–0.814]). In conclusion, our study identified a novel gene pairs signature in the prognosis of GC. [ABSTRACT FROM AUTHOR]

In this work, we propose a novel Deep Convolutional Neural Network (DCNN) tailored for gas classification. Inspired by the great success of DCNN in the field of computer vision, we designed a DCNN with up to 38 layers. In general, the proposed gas neural network, named GasNet, consists of: six convolutional blocks, each block consist of six layers; a pooling layer; and a fully-connected layer. Together, these various layers make up a powerful deep model for gas classification. Experimental results show that the proposed DCNN method is an effective technique for classifying electronic nose data. We also demonstrate that the DCNN method can provide higher classification accuracy than comparable Support Vector Machine (SVM) methods and Multiple Layer Perceptron (MLP). [ABSTRACT FROM AUTHOR]

Purpose: This study investigates the influence of age and axial length (AL) on the peripapillary retinal nerve fiber layer (RNFL) thickness, as measured by optical coherence tomography (OCT). Methods: Healthy patients visiting an eye clinic at a county hospital were recruited. All participants underwent comprehensive ophthalmologic examinations, and their retinas were scanned using 3D OCT-1000. In total, 223 patients with 446 eyes were included. The mean age and AL were 42.07 ± 13.16 (21–76) years and 25.38 ± 1.73 (21.19–30.37) mm, respectively. Results: The average RNFL thickness decreased by 2.71 μm for every 10-year increase in age (P < 0.001). Age-related RNFL thinning was more significant in participants older than 41 years (-0.24μm/year; P = 0.015). The earliest sector showing a significant decline in RNFL thickness was after 35 years of age (-0.70μm/year; P = 0.011) at the superior quadrant and at the 1–2 o’clock hour (-1.42μm/year; P = 0.009). Meanwhile, the maximal rate of age-associated RNFL decay was observed in these two regions as well. The reduction of RNFL with age progression did not differ in eyes with long AL (> 27 mm; -0.16μm/year) or those with short AL (< 25 mm; -0.22μm/year). For every 1-mm-greater AL, RNFL was thinner by 1.78 μm (P < 0.001). The inferior quadrant showed the greatest tendency of RNFL decline with longer AL (4.46 μm/mm; P < 0.001). Conclusions: The factors of age and AL should be considered when interpreting the results. Significantly age-associated RNFL thinning was found in participants older than 41 years. Reduction of RNFL thickness with increasing age was not affected by AL. Topographic variations in RNFL thinning were observed in that the maximal decline of RNFL thickness with advancing age at the superior quadrant whereas with elongation of AL at the inferior quadrant. [ABSTRACT FROM AUTHOR]

Here, we for the first time demonstrated thioflavin T (ThT) as an efficient fluorescent ligand for 27-mer ATP-binding aptamer (ABA27), providing a novel signal readout mode for label-free selective ATP detection. ABA27 can promote the fluorescence emission of ThT with an unprecedentedly high efficiency, attributed to the specific structure of ABA27 rather than the G-tracts. Polyacrylamide gel electrophoresis, fluorescence spectroscopy, and fluorometric titration reveal that ThT interacts with ABA27 with a lower binding affinity (Kd ~89 μM) than ATP, which allows ATP to easily compete with ThT for the DNA binder. In the presence of ThT, adding ATP induces ABA27 to undergo a structural change, thereby not favoring the binding to ThT, verified by circular dichroism and UV-Vis absorption spectroscopy. As a result, the fluorescence intensity of ThT decreases dramatically, enabling the sensitive detection of ATP with high selectivity over other analogs. Such a sensing strategy may make ThT able to serve as a facile signal reporter for DNA nanomechanical devices fueled with ATP. [ABSTRACT FROM AUTHOR]

This paper presents a project called KnowIng camera prototype SyStem (KISS) for real-time places-of-interest (POI) recognition and annotation for smartphone photos, with the availability of online geotagged images for POIs as our knowledge base. We propose a “Spatial+Visual” (S+V) framework which consists of a probabilistic field-of-view (pFOV) model in the spatial phase and sparse coding similarity metric in the visual phase to recognize phone-captured POIs. Moreover, we put forward an offline Collaborative Salient Area (COSTAR) mining algorithm to detect common visual features (called Costars) among the noisy photos geotagged on each POI, thus to clean the geotagged image database. The mining result can be utilized to annotate the region-of-interest on the query image during the online query processing. Besides, this mining procedure also improves the efficiency and accuracy of the S+V framework. Furthermore, we extend the pFOV model into a Bayesian FOV( $\beta$ FOV) model which improves the spatial recognition accuracy by more than 30 percent and also further alleviates visual computation. From a bayesian point of view, the likelihood of a certain POI being captured by phones is a prior probability in pFOV model which is represented as a posterior probability in $\beta$ FOV model.Our experiments in the real-world and Oxford 5K datasets show promising recognition results. In order to provide a fine-grained annotation ground truth, we labeled a new dataset based on Oxford 5K and make it public available on the web. Our COSTAR mining techniqueoutperforms state-of-the-art approach on both dataset. [ABSTRACT FROM PUBLISHER]

Carboxymethyl xylan- g -poly(propylene oxide) (CMX- g -PPO) was successfully synthesized by grafting poly(propylene oxide) chains onto xylan from bamboo using the Al(O i -Pr) 3 initiated ring-opening polymerization of propylene oxides, followed by carboxymethylation with sodium chloroacetate under microwave irradiation. The synthesized CMX- g -PPO was well characterized by FT-IR, 13 C NMR, and AFM. The AFM imaging showed that the average sizes of xylan were 422.1 × 67.4 × 1.2 nm, while the average sizes of grafting branches PPO were 128.0 × 38.5 × 5.1 nm, which firstly provided an irrefutable and visual evidence for the structure of grafted xylan at single molecular level. Subsequently, a serial of CMX- g -PPO/CS films were prepared without addition of any plasticizers. The surface morphologies, wettability, water vapor barrier properties, mechanical properties, and thermal stabilities of the obtained films were characterized and compared with those of the control films by AFM, contact angle, WVP, tensile testing, and TGA, respectively. [ABSTRACT FROM AUTHOR]

We design a flat sub-wavelength lens that can focus acoustic wave. We analytically study the transmission through an acoustic grating with curled slits, which can serve as a material with tunable impedance and refractive index for acoustic waves. The effective parameters rely on the geometry of the slits and are independent of frequency. A flat acoustic focusing lens by such acoustic grating with gradient effective refractive index is designed. The focusing effect is clearly observed in simulations and well predicted by the theory. We demonstrate that despite the large impedance mismatch between the acoustic lens and the matrix, the intensity at the focal point is still high due to Fabry–Perot resonance. [ABSTRACT FROM AUTHOR]

An efficient method for the synthesis of aminomethyl benzimidazoles is developed by using a one-pot batch reaction between amino acids and o-phenylenediamines. This reaction proceeds smoothly in an unmodified household microwave oven, even though scale-up is to 10 g. A desirable method for the quick synthesis of benzimidazoles, which are used as a kind of important intermediates in drug synthesis, is provided by the scale-up utilization of amino acid resource. [ABSTRACT FROM AUTHOR]

Highlights: [•] Microwave-assisted acid hydrolysis was performed at 90°C to produce XOS. [•] No sugar-degraded byproduct was detected in hydrolysates. [•] Acid concentration and reaction time were ascertained by response surface methodology. [•] The maximum XOS yield was achieved with 0.24M H2SO4 for 31min. [•] Acid concentration was a more significant coefficient in XOS production. [ABSTRACT FROM AUTHOR]

A meta-slab composed of subunits with graded thicknesses is proposed for spatially separating the zeroth- and first-order acoustic waveguide modes according to the generalized Snell's law. The phase velocity for the first-order mode depends on the waveguide thickness, whereas that for the zeroth-order mode does not. This enables the required phase-shift gradients of the meta-slab to be obtained for spatially separating the two waveguide modes. To design the meta-slab, analytic solutions are derived for the transmission coefficients and phase shifts of the incident acoustic waves with the two modes propagating through the subunits. Numerical simulations with transient finite-element analyses are implemented to demonstrate the propagation of the two waveguide modes. Sinusoidal signal and tone-burst excitations are applied in the analyses. The latter case shows that the two waveguide modes can be successfully separated in space by the designed meta-slab. [ABSTRACT FROM AUTHOR]

[Display omitted] • Gluten network goes through disassembly and repolymerization during processing. • β-sheets are positively associated with gluten polymerization and dough viscosity. • The stronger dough gluten inhibits starch pasting more significantly. • Covalent protein-starch interactions are found in strong-gluten dough. • Additional protein-starch complexes in dough matrix retard starch retrogradation. To clarify the detailed behaviors of protein, starch and interactions during complex dough processing, structural changes in dough protein and starch during continuous Mixolab processing were investigated using wheat near-isogenic lines carrying high-molecular-weight glutenin subunits 1Dx5 + 1Dy10 (5 + 10) or 1Dx2 + 1Dy12 (2 + 12) at the Glu-D1 locus. A more stable gluten network including disulfide bonds and hydrophobic interactions, was formed in the 5 + 10 dough before dough weakening at 53.5 °C, than in the 2 + 12 dough. Thereafter, thermo-mechanical treatment induced the depolymerization of gluten until starch gelatinization peak at 74.6 °C; however, from the peak to trough viscosity at 82.8 °C, additional monomeric proteins were incorporated into the repolymerized proteins characterized by increased disulfide bonds, hydrogen bonds, and β-sheets. Generally, the protein aggregates of 5 + 10 showed a higher degree of polymerization and better stability than those of 2 + 12 during dough processing, which significantly slowed starch gelatinization and recyclization. Moreover, stronger interactions between monomeric proteins and amylose/short-branch starch via glycosidic and hydrogen bonds were found in 5 + 10 dough during starch pasting and retrogradation. The findings demonstrate the feasibility of optimizing the texture and digestibility of wheat-based food products by regulating the behaviors and interactions of proteins and starch during dough processing. [ABSTRACT FROM AUTHOR]

During the studies on the intramolecular cyclization of 4-arylamino-2(5H)-furanones via the Pd-catalyzed C-H activation, a kind of difunctionalization reaction caused by the designed oxidant PhI(OAc)2[(diacetoxyiodo)benzene, DIB] was accidentally discovered. When 1.5 eq. DIB is used as a difunctionalizable transfer reagent in the 40 h reaction at 60°C and CH3CN as solvent, 4-diarylamino-3-iodo-2(5H)-furanones can be obtained with the yields of 57–91% (usually more than 73%). The simultaneousα-iodination andNβ-arylation reaction without metal catalyst is efficient and convenient. This novel utilization with a greater atom economy provides a simple and practical conversion route for the synthesis of the potential biological 2(5H)-furanone compounds containing multifunctional groups. [ABSTRACT FROM AUTHOR]

The content of intermetallic compounds (IMCs) in friction stir lap welded (FSLW) dissimilar joints of Mg and Al alloys could be reduced by the addition of interlayer metal to improve the mechanical properties of the joints, while the underlying mechanism is still unclear. In this study, Cu and Ni powders are added as the interlayer materials into the FSLW joints of AZ31 Mg alloy and Al–Zn–Cu–Mg alloy, respectively. The types, sizes, and distributions of IMCs have been characterized, and the shear properties of the joints have been evaluated. Moreover, the mechanism underlying the influence of the interlayer metals on the evolution of IMCs in the joints and the effect of IMCs on the shear properties of the joints have been studied. The results showed that the order of phase formation in the joint without interlayer was Al 12 Mg 17 , Al 3 Mg 2 , MgZn 2 , CuMg 2 , Al 2 Cu, while the order of phase formation in the joint with added Cu interlayer was Al 2 Cu, CuMg 2 , AlCu, Al 12 Mg 17 , Al 3 Mg 2 , Cu 5 Zn 8 , and that in the joint with added Ni interlayer was Mg 2 Ni, Al 3 Ni, Al 3 Ni 2 , MgNi 2 , AlNi, Al 12 Mg 17 , Al 3 Mg 2 , MgZn 2 , Ni 3 Zn 22 , NiZn, Al 2 Cu. Due to the formed physical barrier and the mechanism of phase formation, the addition of interlayer metal effectively inhibited the formation of a Mg–Al phase. The bonding strengths between Mg–Cu, Al–Cu, Al–Ni, and Mg–Ni phases and matrix were higher than that between Mg–Al phase and matrix, which improved the shear properties of the joints with Cu and Ni interlayers. [ABSTRACT FROM AUTHOR]

• HMW-GSs 5 + 10 contributed to a more extensive and compact protein-starch complex. • More monomeric proteins were involved into gluten possessing subunits 5 + 10. • Subunits 5 + 10 can cause low starch gelatinization degree in dough matrix. • Subunits 2 + 12 contributed to a fragile gluten network with low thermal stability. • The ratio of β-sheets to α-helix was positively associated with dough consistency. Differences in Mixolab measurements of dough processing were examined using, as a base, flour from pure breeding, isogenic, wheat lines carrying either the high molecular weight glutenin subunits 5 + 10 or 2 + 12. Before dough pasting, subunits 5 + 10 tend to form a stable gluten network relying mainly on disulfide bonds and hydrogen bonds, but 2 + 12 flour was prone to generating fragile protein aggregates dominated by disulfide bonds and hydrophobicity. During dough pasting, a broader protein network rich in un-extractable polymeric proteins, disulfide bonds and β-sheets was formed in the dough with subunits 5 + 10, thus resulting in an extensive and compact protein-starch complex which was characterized by high thermal stability and low starch gelatinization, while in the dough of the 2 + 12 line, a porous protein-starch gel with fragmented protein aggregates was controlled by the combination of disulfide bonds, hydrophobicity and hydrogen bonds that facilitated the formation of antiparallel β-sheets. [ABSTRACT FROM AUTHOR]

DewaxedCalamagrostis angustifoliaKom was pretreated with hot water at 60 and 90°C for 3 h, and then the residue obtained was successively treated with 70% ethanol, and 70% ethanol containing 0.2%, 1.0%, 2.0%, 4.0%, and 8.0% NaOH at 80°C for 3 h. The dissolved components were subjected to further separation to get eight lignin fractions, which were characterized by gel permeation chromatography, Fourier transform infrared, and sugar analysis. All the lignin fractions had small weight-average molecular weights between 810 and 2580 g/mol. Two typical lignins, L3(prepared with 70% ethanol) and L5(prepared with 70% ethanol containing 1.0% NaOH), were further analyzed using1H,13C NMR and HSQC spectroscopy. Signals from guaiacyl (G), syringyl (S), andp-hydroxyphenyl (H) units observed in aromatic/olefinic region of HSQC spectra indicated that the lignin fromCalamagrostis angustifoliaKom could be classified as “GSH” lignin. In aliphatic-oxygenated region, β-O-4′ together with small amounts of β-5′, β-β′, andp-hydroxycinnamyl alcohol end group were the main interunit linkages observed. Aqueous ethanol, which could avoid the cleavage of ether bonds in lignin at neutral condition, was more effective than water on lignin extraction. [ABSTRACT FROM AUTHOR]

A novel cellulose- click-chitosan polymer was prepared successfully in three steps: (1) propargyl cellulose with degrees of substitution (DS) from 0.25 to 1.24 was synthesized by etherification of bamboo Phyllostachys bambusoide cellulose with propargyl chloride in DMA/LiCl in the presence of NaH. The regioselectivity of propargylation on anhydrous glucose unit determined by GC-MS was in the order of 2 >> 6 > 3; (2) the functional azide groups were introduced onto the chitosan chains by reacting chitosan with 4-azidobenzoic acid in [Amim]Cl/DMF and the DS ranged from 0.02 to 0.46; (3) thus, the cellulose- click-chitosan polymer was obtained via click reaction, that is, the Cu(I)-catalyzed Huisgen 1,3-dipolar cycloaddition reaction, between the terminal alkyne groups of cellulose and the azide groups on the chitosan backbone at room temperature. The successful binding of cellulose and chitosan was confirmed and characterized by FTIR and CP/MAS 13C NMR spectroscopy. TGA analyses indicated that the cellulose- click-chitosan polymer had a higher thermal stability than that of cellulose and chitosan as well as cellulose-chitosan complex. More interestingly, some hollow tubes with near millimeter length were also observed by SEM. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012 [ABSTRACT FROM AUTHOR]

The chemical composition and structural characterization of the milled wood lignin (MWL) and successively alkali-fractionated lignins from bamboo ( Phyllostachys incarnata Wen) were comparatively investigated using Fourier transform infrared (FT-IR), gel permeation chromatography (GPC), 2D heteronuclear single quantum coherence (HSQC), and alkaline nitrobenzene oxidation. It was found that bamboo MWL (S/G ~ 1.3) is of SGH type with a considerable amount of esterified p-coumaric acid and etherified ferulic acid. Molecular weights of 3,320 g/mol for MWL and varying weights between 970 and 3,430 g/mol for the alkali-fractionated lignins were obtained. Moreover, 2D HSQC of MWL showed a predominance of β- O-4′ linkages (65%), followed by β-β′ linkages (15%) and lower amounts of β-5′ (7%), β-1′ (4%), 5-5′ (4%) linkages, and cinnamyl acetate end groups (5%). In addition, a percentage (~45%) of the lignin side chain was found to be acylated at the γ-carbon. However, the alkali-fractionated lignins lost parts of these linkages during successive alkaline fractionation processes. [ABSTRACT FROM AUTHOR]