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Seaweed sulfated polysaccharides have attracted significant attention due to their antibacterial activity. This work investigated the antibacterial activity and mechanism of depolymerized sulfated galactans from Eucheuma serra (E. serra) and Gracilaria verrucosa (G. verrucosa) against enterotoxigenic Escherichia coli (ETEC) K88. The results show that removing the metal ions improves the anti-ETEC K88 activity of the galactans. The fluorescence labeling study confirmed that the sulfated galactans penetrated the cell walls and eventually reached the interior of the ETEC K88. Nucleic acid staining and intracellular protein leakage were also observed, indicating the destruction of permeability and integrity of the cell membrane. Interestingly, the two polysaccharides exhibited no effect on the proliferation of the selected Gram-positive bacteria and yeast. This indicates that the cell wall structure of the microorganisms could influence the bacteriostatic activity of the sulfated polysaccharides, as well. These results suggest that the sulfated seaweed polysaccharides might have potential application value in antibacterial diarrhea.

Building fire is one of the major threats to human beings now. This paper presents a quantitative method based on social network analysis (SNA) for evaluating the cause and risk index of building fire. Firstly, available data from 67 case reports of major building fire accidents is extracted. In order to analyze the patterns and characteristics of major road building fire accidents, a relationship network map is constructed by using SNA. By establishing a building fire risk index system, this paper also lists common fire risks and causes. The result results can further deepen the understanding of the causes of construction fire accidents and the interaction between them. Through SNA, this paper finds the key causes of building fire accidents, and which combinations of causes are most likely to cause accidents. The establishment of risk indicator system can provide reference for fire prevention and early warning work.

A growing number of studies suggest that fatty acids (FAs) as ligands can improve protein's affinity to hydrophobic small molecules. Therefore, this work investigated FA-mediated protein encapsulation to simultaneously improve the water-solubility, storage stability, and oral absorption of astaxanthin (ASTA). As the main dietary FAs, lauric acid (LAA, C12:0), palmitic acid (PA, C16:0), stearic acid (SA, C18:0), oleic acid (OA, C18:1), linoleic acid (LA, C18:2), arachidonic acid (AA, C20:4), and docosahexaenoic acid (DHA, C22:6) were compared. The results showed that all the selected FAs increased the efficiency of bovine serum albumin (BSA) in encapsulating ASTA. The self-assembled particles mediated by SA exhibited smaller particle sizes, a higher Zeta potential, and better clarity in water. Contrarily, DHA led to a sharp increase in particle size and turbidity. All the fabricated FA-BSA complexes significantly (P PA > LAA > OA > AA > LA > DHA). The simulated digestion results showed that except for DHA, the FAs with longer carbon chain lengths or unsaturated double bonds played a better role in improving ASTA's bioaccessibility. The in vivo absorption results further confirmed that the protein encapsulation mediated by C18–C20 FAs was more conducive to ASTA absorption. These findings suggest that FA-protein complexes may be suitable as the hydrophilic delivery carriers for hydrophobic nutrients. However, different FAs may play different roles in regulating nutrient stability and absorption.

Human-robot coexistence has become an important trend of the new generation of robots. Both rigid structures and soft structures have their own limitations in certain application scenarios. The tensegrity structure, which is widely used in the field of architecture and structural engineering, is a self-supporting and self-stressed spatial grid structure composed of discrete compression elements and continuous tension elements. This kind of structure combines the advantages of rigid structures and soft structures, and conforms to the natural evolutionary laws of creatures, providing helpful inspirations for the research of the new generation of robots. Tensegrity structures are being more and more widely used in robotics. The objective of this paper is to review the state-of-the-art of tensegrity structures-based robots and analyze the key techniques in aspects of design and fabrication, modeling and analysis, motion and controlling. Possible future applications of tensegrity robots are also prospected. Although there are still few actual applications in practice, tensegrity structures-based robots, as a unique rigid-flexible coupling structure, have great potentials in the future.

The viscosities of the MnO (0 to 55 mass pct)-CaO-SiO2-MgO (5 mass pct)-Al2O3 (20 mass pct) melts were measured by rotating cylinder method in the temperature range from 1573 K to 1873 K (1300 °C to 1600 °C). The measurements were carried out in the atmosphere of flowing CO/CO2 gas mixture with a volume ratio of 99/1, and molybdenum crucible and spindle were adopted. The results reveal that MnO is a viscosity reducing component, and the effect of MnO is more notable in the melts with higher ratio of CaO to SiO2. For example, in the melts with the mass ratio of CaO to SiO2 equal to 0.6, the addition of 5 mass pct MnO only slightly reduced the viscosities. Comparatively, the addition of 5 mass pct MnO made the viscosities of the melts with the mass ratio of CaO to SiO2 equal to 1.0 and 1.5 decrease remarkably. Based on the measured data, the viscosities estimation model proposed in our previous study was extended to the system containing MnO, and the model parameters were determined. The model can estimate and predict the viscosities of the aluminosilicate melts containing MnO well, and then some iso-viscosity contours of this system were calculated. From the iso-viscosity contours, it can be seen that MnO is almost equivalent to CaO in reducing the viscosities in the melt with high SiO2 content, while with the decrease of the SiO2 content MnO becomes more effective than CaO.

Active polysaccharides as safe and natural polymers against bacterial diarrhea have been reconsidered as an alternative to antibiotics. This work investigated the inhibiting effect of depolymerized sulfated galactans from Eucheuma serra and Gracilaria verrucosa on the growth and adhesion of diarrheagenic enterotoxigenic Escherichia coli (ETEC) K88. Results showed that the sulfated polysaccharides with molecular weight distribution &le, 20.0 kDa exhibited antibacterial activity against ETEC K88. A structure&ndash, activity study revealed that the anti-ETEC K88 activity of sulfated polysaccharides is strictly determined by their molecular weight distribution, sulfate group content, and monosaccharide composition. In addition, the promoted nucleic acid release and the fluorescence quenching of membrane proteins were observed after the treatment with selected polysaccharides. Scanning electron microscopy further confirmed that the depolymerized sulfated galactans can effectively inhibit ETEC K88 adhesion. In conclusion, depolymerized sulfated galactans exhibited an inhibitory effect on the growth and adhesion of ETEC K88.

Achieving versatile and efficient walking on biped robots is an important research objective. The impact between the foot and the ground has significant effects on the walking stability of biped robots. Research on human walking indicates that the joints in human lower limbs show different stiffness values in different phases of walking. Inspired by humans, this paper presents the realization of biped robot walking with variable stiffness at the ankle joint. A walking control scheme which combines PD control and variable impedance control is designed for the biped robot. Results of dynamic walking simulation verified that variable stiffness at the ankle joint could contribute to the improvement of walking stability and energy efficiency.

The minimum of tooth surface flash temperature and vibration acceleration RMS design is proposed and analyzed. The tooth contact analysis (TCA) and the load tooth contact analysis (LTCA) method and multi-objective optimization are also detailed. Satisfying design variables in multiple physical quantities leads to the minimum of multi-objective optimization. Considering the tooth surface loading conditions are uniform or not, the optimal modification of the tooth surface for improving gear comprehensive characteristics under various load bearing conditions is improved. The tooth surface flash temperature and vibration acceleration root mean square (RMS) values in different transmission modes of marine ship power rear gears drive system are derived. This research considers the multi-objective optimization modifications of tooth surface, and its main purpose is to propose an approach to help design tooth corrections to simultaneously optimize several objective physical quantities.

PhoB is a response regulator of the PhoR/PhoB two-component signal transduction system that is involved in the regulation of the phosphate (Pho) regulon of Escherichia coli. PhoB has two domains, receiver domain and effector domain. The receiver domain can be phosphorylated by its cognate histidine kinase PhoR and the phosphorylation induces conformational changes of the full length protein of PhoB that promote the DNA binding and transcription. Three-dimensional crystal structures of PhoB receiver domain (PhoBN) have been solved under apo or BeF3− (a phosphoryl analog) binding forms and it has been found that PhoBN is dimerized in both situations. However, we have found that the apo form of PhoBN has multiple conformational changes in solution that is hard to be distinguished by using NMR spectroscopy, while the mutagenesis of F20D PhoBN gives homogeneous dispersed signals in HSQC spectrum indicating a relatively uniform conformation. Meanwhile the F20D mutant has the same phosphorylation activity as the wild type protein. Here we report the backbone assignment of PhoBNF20D mutant. The chemical shift (HN, N, CO, Cα and Cβ) analysis shows that the predicted regions of secondary structure are in good agreement with those observed in the crystal structure of apo PhoBN. Therefore, the backbone chemical shifts assignment of PhoBNF20D mutant would be useful for studying the structure and dynamics of PhoB receiver domain and it has significance for explaining the mechanism of phosphorylation in TCSs.

Histidine kinases are key regulators in the bacterial two-component systems that mediate the cellular response to environmental changes. The vast majority of the sensor histidine kinases belong to the bifunctional HisKA family, displaying both kinase and phosphatase activities toward their substrates. The molecular mechanisms regulating the opposing activities of these enzymes are not well understood. Through a combined NMR and crystallographic study on the histidine kinase HK853 and its response regulator RR468 from Thermotoga maritima, here we report a pH-mediated conformational switch of HK853 that shuts off its phosphatase activity under acidic conditions. Such a pH-sensing mechanism is further demonstrated in the EnvZ-OmpR two-component system from Salmonella enterica in vitro and in vivo, which directly contributes to the bacterial infectivity. Our finding reveals a broadly conserved mechanism that regulates the phosphatase activity of the largest family of bifunctional histidine kinases in response to the change of environmental pH., Bacteria adapt to changing environmental conditions through signal transduction mediated by the two-component system (TCS). Here, the authors combine X-ray crystallography and NMR studies to characterize a pH-gated conformational switch that regulates the phosphatase activity of TCS bifunctional histidine kinases.

Given the adverse impact of ultraviolet irradiation on human skin, as well as currently limited interventions, the discovery of new molecules with anti-photodamage potency remains critical. In this research, we obtained a new bioactive peptide (named OS-LL11, amino acid sequence 'LLPPWLCPRNK') from Odorrana schmackeri. Results showed that OS-LL11 could directly scavenge free radicals and sustain the viability of mouse keratinocytes challenged by ultraviolet B (UVB) irradiation or hydrogen peroxide (H2O2) by decreasing the levels of lipid peroxidation, malondialdehyde, and reactive oxygen species while increasing the level of catalase, Keap-1, HO-1, GCLM, and NQO1. Interestingly, topical application of OS-LL11 protected mouse skin against UVB irradiation damage by up-regulating the levels of superoxide dismutase, glutathione, and nitric oxide, but down-regulating the levels of H2O2, IL-1α, IL-1β, IL-6, TNF-α, 8-OHdG, Bcl-2, and Bax, as well as the number of apoptotic bodies. Our research demonstrated the anti-photodamage activity of a novel amphibian-derived peptide and the potential underlying mechanisms related to its free radical scavenging ability and antioxidant, anti-inflammatory, and anti-apoptotic activities. This study provides a new molecule for the development of anti-skin photodamage drugs or cosmetics and highlights the prospects of amphibian-derived peptides in photodamaged skin intervention.

In nano EM, although the machined voltage is just several volts, the machined gap is only several angstroms to several nanometers, resulting in extremely high electric strength (>109 V/m). How the electric field influences the material removal has not been revealed, which is one of the most fundamental problems unsolved in nano EM. To investigate the electric field distribution in nano EM, a FE simulation was conducted. The simulation results demonstrated that the electric field distribution in nano EM can be approximately expressed by a Gaussian distribution which can be used as the electric field model in MD simulation. To reveal the material removal of nano EM, a MD simulation was carried out based on the FE simulation results of the electric field distribution. MD simulation results shows that the charged atoms can overcome the binding force among atoms under the action of the electric field force, then broke away from the workpiece. Furthermore, the higher the gap voltage was, the more the removed charged atoms were because of much higher electric force. During the removal process of the charged atoms, the uncharged atoms were also taken away from the workpiece surface by the charged atoms due to the binding forces among atoms. Furthermore, around the edge of the charged area, the uncharged atoms were dragged by the charged atoms, but they were not separated from the workpiece surface due to relatively small electric field force, which forming a bulge. It was also found that as the workpiece temperature rose, the bonding force among atoms weakened, thus, the atoms on the workpiece surface could be removed easily, resulting in more atoms removal number in nano EM.

In this study, a combination of experimental characterization and first-principles calculation was employed to systematically study the structure and electronic properties of Cr-coating prepared on the surface of oxide dispersion strengthened (ODS) steel by pack-cementation chromizing. X-ray diffraction (XRD) and energy dispersive spectrometer (EDS) results show that the Cr-coating is mainly composed of Cr2C and Fe2Y phases. The first-principles calculation results show that the Cr atoms and C atoms in the Cr2C crystal are bonded by ionic bonds, while the Fe atoms and Y atoms in the Fe2Y crystal are mainly boned by polar covalent bonds. Compared with Fe2Y, Cr2C crystal has greater elastic anisotropy. The elastic constant of Cr2C crystal increases significantly with the increase of pressure. When the pressure reaches 2.4 GPa, Cr2C undergoes a transition from ductile to brittle. The elastic modulus of Fe2Y increases slowly with increasing pressure, and always appears as a ductile phase under the pressure value of 0–6 GPa, which is considered to have a good effect on the impact properties of the Cr-coating. The average work function of Cr2C crystal electrons is greater than that of Fe2Y crystal electrons, indicating that when the coating is in a corrosive medium, the Fe2Y phase will serve as the anode in the electrode first, and will be corroded before the Cr2C phase.

Fucoidans, sulfated polysaccharides in brown algae, were depolymerized though high-pressure hydrolysis, and their antibacterial activity, structural properties, and antibacterial mechanisms were investigated in this work. The fucoidans from Laminaria japonica show no antibacterial activity before depolymerization; however, their depolymerized products can effectively (p

Background High-performance position control of pneumatic artificial muscles is limited by their inherent nonlinearity and hysteresis. Objective This study aims to model the length/pressure hysteresis of a single pneumatic artificial muscle and to realize its accurate position tracking control with forward hysteresis compensation. Methods The classical Prandtl-Ishlinskii model is widely used in hysteresis modelling and compensation. But it is only effective for symmetric hysteresis. Therefore, a modified Prandtl-Ishlinskii model is built to characterize the asymmetric length/pressure hysteresis of a single pneumatic artificial muscle, by replacing the classical play operators with two more flexible elementary operators to independently describe the ascending branch and descending branch of hysteresis loops. On the basis, a position tracking controller, which is composed of cascade forward hysteresis compensation and simple proportional pressure controller, is designed for the pneumatic artificial muscle. Results Experiment results show that the MPI model can reproduce the length/pressure hysteresis of the pneumatic artificial muscle, and the proposed controller for the pneumatic artificial muscle can track the reference position signals with high accuracy. Conclusion By modelling the length/pressure hysteresis with the modified Prandtl-Ishlinskii model and using its inversion for compensation, precise position control of a single pneumatic artificial muscle is achieved.

Pneumatic artificial muscles have been widely used in various fields owing to their inherent compliance and high power-to-weight ratio. However, the natural hysteresis nonlinearity including length/pressure hysteresis and force/pressure hysteresis degrades their performance in precise tracking control, making it necessary to build a mathematical hysteresis model for hysteresis compensation. This paper deals with the modelling of length/pressure hysteresis of pneumatic artificial muscles. The length/pressure hysteresis loops measured by the isotonic test are found to be asymmetric and independent of the external load when the load is small. Considering that the classical Prandtl-Ishlinskii model is only effective for symmetric hysteresis, a modified Prandtl-Ishlinskii model is proposed to describe the length/pressure hysteresis behaviour. The developed model utilizes two asymmetric operators with simple mathematical forms to independently model the ascending branch and descending branch of hysteresis loops. The model parameters are identified using the recursive least square algorithm. Comparisons between simulation results and experimental measurements demonstrate that the proposed model can characterize the asymmetric major hysteresis loop and minor hysteresis loops with high accuracy. Pnevmatične umetne mišice (PAM) so razmeroma nova vrsta elastičnih pnevmatičnih izvršnih členov. Zaradi svoje netogosti ter velikega razmerja med močjo in maso so se uveljavile na različnih področjih uporabe. Njihova naravna nelinearnost, ki vključuje histerezo dolžine/tlaka in histerezo sile/tlaka, pa povečuje sistemsko nelinearnost ter zmanjšuje sposobnost natančnega sledenja. Ena od rešitev za premostitev te težave je postavitev matematičnega modela histereze ter uporaba njegovega inverza za kompenzacijo histereze in doseganje približno linearnega odziva PAM. Članek obravnava modeliranje histereze dolžine/tlaka pri PAM. Histereza dolžine/tlaka se meri z izotoničnim testom ob predpostavki kvazistatičnosti procesa, meritve pa nakazujejo obstoj večje in manjše histerezne zanke med hitrostjo krčenja in notranjm tlakom PAM. Te histerezne zanke so asimetrične ter niso odvisne od manjših zunanjih obremenitev.

Interest in phlorotannins has increased in recent years largely due to antioxidant capacity, however, the redox mechanism of phlorotannins is still obscure. In the present study, the electrochemical oxidation mechanisms of eckol (EL) and phlorofucofuroeckol-A (PFF-A), two representative phlorotannin compounds, were comparatively analyzed in a wide pH range using cyclic and differential pulse voltammetry as well as spectroscopic assay. The voltammetric study revealed that EL and PFF-A were successively oxidized in three pH-dependent steps. Moreover, it was found that the PFF-A presented a stronger proton and electron transferring activity as compared to EL since PFF-A exhibited lower acid-base dissociation constant (pKa ) value and higher heterogeneous rate constant (kbh ) value in the first oxidation step. These property were further evidenced by comparison of direct antioxidant activity (i.e., superoxide anion and peroxide radicals) as well as indirect antioxidant activity (i.e., mRNA expression of two phase II enzymes) between EL and PFF-A. PRACTICAL APPLICATIONS: Phlorotannins from edible algae have been regarded as novel antioxidants those presented high application potential in food industry. Even though antioxidant activity of phlorotannin compounds have been widely investigated in both in vitro and in vivo studies, very few reports focused on electron transferring functionality which is chemical basis for antioxidant process. Herein, the oxidative mechanisms of two representative phlorotannins were comparatively analyzed using multiple electrochemical methods. This is hopefully to give information on the chemical meaning behind the antioxidant activity of dietary phlorotannins.

The two-component system (TCS) is a significant signal transduction system for bacteria to adapt to complicated and variable environments, and thus has recently been regarded as a novel target for developing antibacterial agents. The natural product luteolin (Lut) can inhibit the autophosphorylation activity of the typical histidine kinase (HK) HK853 from Thermotoga maritime, but the inhibition mechanism is not known. Herein, we report on the binding mechanism of a typical flavone with HK853 by using solution NMR spectroscopy, isothermal titration calorimetry (ITC), and molecular docking. We show that luteolin inhibits the activity of HK853 by occupying the binding pocket of adenosine diphosphate (ADP) through hydrogen bonds and &pi, &pi, stacking interaction structurally. Our results reveal a detailed mechanism for the inhibition of flavones and observe the conformational and dynamics changes of HK. These results should provide a feasible approach for antibacterial agent design from the view of the histidine kinases.

Aim To develop and validate 3 nomograms incorporating the advanced lung cancer inflammation index (ALI) that can aid in predicting the risk of coronary artery disease (CAD) and coronary artery calcification (CAC). Methods The study enrolled 562 consecutive patients with suspected CAD who underwent coronary computed tomographic angiography between September 2015 and June 2017. Independent risk factors for CAD, CAC, and CAD with CAC were identified via univariate and multivariate analysis, and nomograms were established based on the independent predictors identified. The area under the curve (AUC), calibration curve, and decision curve analysis were used to evaluate the nomograms. Correlations between ALI and other clinical indicators were examined via Spearman correlation analysis. Results In total, 549 patients with suspected CAD who underwent coronary computed tomographic angiography were included. Male sex, hypertension, diabetes, dyslipidemia, ischemic stroke, and ALI were independent predictors of both CAD and CAC. Male sex, hypertension, diabetes, dyslipidemia, and ALI were also identified as independent predictors of CAD with CAC. The AUC values for the nomograms developed using these risk factors were 0.739 (95% confidence interval [CI], 0.693-0.785), 0.728 (95% CI, 0.684-0.772), and 0.717 (95% CI 0.673-0.761), respectively. ALI was negatively correlated with neutrophil-to-lymphocyte ratio and CAC score and positively correlated with serum albumin levels and body mass index (all P Conclusions ALI is an independent predictor of CAD, CAC, and CAD with CAC. Our ALI-based nomograms can provide accurate and individualized risk predictions for patients with suspected CAD.

With increasingly serious eye exposure to light stresses, such as light-emitting diodes, computers, and widescreen mobile phones, efficient natural compounds for preventing visible light-induced retinal damages are becoming compelling needs in the modern society. Fucoxanthin, as the main light absorption system in marine algae, may possess an outstanding bioactivity in vision protection because of its filtration of blue light and excellent antioxidative activity. In this work, both in vitro and in vivo simulated visible light-induced retinal damage models were employed. The in vitro results revealed that fucoxanthin exhibited better bioactivities than lutein, zeaxanthin, and blueberry anthocyanins in inhibiting overexpression of vascular endothelial growth factor, resisting senescence, improving phagocytic function, and clearing intracellular reactive oxygen species in retinal pigment epithelium cells. The in vivo experiment also confirmed the superiority of fucoxanthin than lutein in protecting retina against photoinduced damage. This excellent bioactivity may be attributed to its unique structural features, including allenic, epoxide, and acetyl groups. Fucoxanthin is expected to be an important ocular nutrient in the future.

An isotope enrichment system for 39Ar has been developed at the Institute of Modern Physics, which is designed to increase the abundance of 39Ar in the incident sample gas. With intense Ar+ beams produced by a 2.45 GHz electron cyclotron resonance ion source and a high mass resolution spectrometer system, Ar isotopes are evidently separated on the target plane and selectively collected by an Al target. The separated Ar isotopes have been identified on the target plane, which is consistent with the simulations. According to the recent cross-checked results with atom trap trace analysis, a high enrichment factor of 39Ar has been successfully achieved. This paper will present the design and test results of this system.

A very compact permanent magnet 2.45 GHz electron cyclotron resonance ion source has been designed and developed for various purposes. The microwave power is coupled into the plasma chamber using the coaxial antenna instead of the waveguide, the magnetic field is produced by two NdFeB permanent magnet rings, and the diameter of the source body is only 10 cm. The beam current under different conditions was measured. A maximum of 5.8 mA H+/H2+/H3+ mixed beam could be extracted from a 5.5 mm diameter extraction aperture.

Objective: Effective isolation management of multiple drug resistant organism (MDRO) patients is considered an important measure to prevent cross-infection. To reduce the spread of MDRO, there is a need to improve the correct implementation of isolation measures for intensive care unit (ICU) medical personnel. We will investigate the application of quality control circle (QCC) activities in improving the correct implementation rate of isolation measures for patients with MDRO in ICU medical personnel. Methods: A 10-member QCC activity group was established. All of the ICU medical personnel were taken as the research objects, including doctors, nurses, assistant nurses, rotation training personnel, external ICU consultants and cleaning personnel. The correct implementation of isolation measures for patients with MDRO infection were investigated and studied, which identified the problem areas and analyzed the main reasons. The quality improvement countermeasures were formulated and implemented in ICU medical personnel, while the results were compared with before and after the QCC activities. Results: After QCC activities, the correct implementation rate of isolation measures by ICU medical personnel for patients with MDRO infection increased from 57.7% to 82.4%. The incidence of MDRO infection in ICU patients decreased from 9.64% to 3.77%, with statistically significant differences (P < 0.05). Conclusion: The QCC activities improved the correct implementation rate of MDRO isolation measures by ICU medical personnel, standardizing the isolation management of MDRO patients, while the incidence of MDRO in ICU patients was also effectively reduced.

Although dietary polyphenols are known to be beneficial to vision, the protective distinctions among different types of polyphenols are unclear. In this work, the visual benefits of various blueberry polyphenols were evaluated using an in vitro model of visible light-lipid-induced injury of retinal pigment epithelial cells. Results showed that, at 10.0 μg/mL, the phenolic acid-rich fraction was superior in inhibiting cell death (93.6% ± 2.8% of cell viability). Anthocyanin- and flavonoid-rich fractions shared similar advantages in preventing the expression of senescence-associated β-galactosidase (34.8% ± 11.1% and 32.2% ± 9.7% of aged cells, respectively) and overexpression of vascular endothelial growth factor (51.8 ± 3.5 and 54.1 ± 6.5 pg/mL, respectively). The flavonoid-rich fraction also showed high activity in ameliorating phagocytosis (70.3% ± 12.6%) and cellular oxidative stress. These results were further confirmed by using the corresponding polyphenol standards. Improved inhibitory effects of polyphenol mixture on cell death and senescence-associated β-galactosidase expression were also observed. Therefore, various polyphenols play diverse roles and exert synergistic effects in nourishing the retina.

This paper presents the development of human-machine interaction control system of a remote maintenance manipulator for tokamak utilizing virtual reality. The human-machine interaction control system aims to achieve three major functions as virtual simulation, human-machine interaction, and collision detection. The graphical user interface of the control system is developed with the aid of the software Unity3D. In order to simplify system operations and improve user experience, 3D mouse and somatosensory controllers are adopted to realize scene exploration in the virtual environment and master-slave interaction control of the manipulators. A typical maintenance task is simulated using the human-machine interaction control system. The results indicate that the developed control system can help improve the safety and efficiency of remote maintenance operations significantly.

Inverse kinematics is quite an important issue for redundant manipulator arms. This paper presents the kinematics analysis including forward kinematics and inverse kinematics for a large-scale heavy-load redundant manipulator arm. Firstly, the overview of the heavy-load redundant manipulator arm which is developed for a multi-purpose remote maintenance system for tokamak is introduced. After that, the forward kinematics of the manipulator arm is analyzed using D-H method, and simulated in Matlab. Finally, the inverse kinematics of the manipulator arm is investigated by combining the gradient projection method and obstacle avoidance optimization in order to solve the redundancy of the manipulator arm. The work in this paper is the basis for path planning of redundant manipulator arms.

The foot-ground impact is a vital problem for biped robots walking stability. Various works have been done to reduce the impact and enhance the walking stability. This paper investigates the foot-ground impact using mathematic models and introduces the design of a pneumatic variable stiffness ankle joint. First, the torque and energy consumption of the ankle joint during double support phase are derived from a seven-link idealized model. Then, in order to find the optimal range of ankle stiffness, dynamic simulations are conducted on two virtual prototypes with variable stiffness ankle and rigid ankle respectively. After that, a pneumatic unit is designed based on the simulation results and a test is performed to measure its range of stiffness. Finally, combining the pneumatic unit with a parallelogram mechanism, an integrated variable stiffness ankle joint is developed.

Human walking is quite an efficient and smooth movement involving multiple successive phases. But for biped robots, most current dynamic walking models are simplified to some extent, with some phases neglected. This paper addresses the development of a complete multi-phase dynamics model for a biped robot. To achieve this, both the single support phase and double support phase are divided into two sub-phases by taking into consideration the rotation of stance foot around its toe and the rotation of swing foot around its heel. Therefore, a more human-like robotic gait is achieved, with transitions occurring at toe-off, heel-off, heel-strike, and toe-strike. Comparing the numbers of degrees of freedom with independent actuators of the biped robot, the whole gait cycle can also be represented by fully-actuated phase, under-actuated phase, and over-actuated phase. On this basis, the detailed dynamics model of each phase is derived using Euler-Lagrange method. And the validity of the dynamics model is demonstrated by simulation.

Geologic reconstructions of the Main Himalayan Thrust in Nepal show a laterally extensive midcrustal ramp, hypothesized to form the downdip boundary of interseismic locking. Using a recent compilation of interseismic GPS velocities and a simplified model of fault coupling, we estimate the width of coupling across Nepal using a series of two‐dimensional transects. We find that the downdip width of fault coupling increases smoothly from 70 to 90 km in eastern Nepal to 100–110 km in central Nepal, then narrows again in western Nepal. The inferred coupling transition is closely aligned with geologic reconstructions of the base of the midcrustal ramp in central and eastern Nepal, but in western Nepal, the data suggest that the location is intermediate between two proposed ramp locations. The result for western Nepal implies either an anomalous coupling transition that occurs along a shallowly dipping portion of the fault or that both ramps may be partially coupled and that a proposed crustal‐scale duplexing process may be active during the interseismic period. We also find that the models require a convergence rate of 15.5 ± 2 mm/year throughout Nepal, reducing the geodetic moment accumulation rate by up to 30% compared with earlier models, partially resolving an inferred discrepancy between geodetic and paleoseismic estimates of moment release across the Himalaya. NRF (Natl Research Foundation, S’pore) MOE (Min. of Education, S’pore) Published version

The metatarsophalangeal (MTP) joints play critical roles in the push-off phase of human locomotion, but are usually absent in biped robots. Our previous research found that when the unilateral MTP joints were restricted, non-disabled subjects exerted a compensatory mechanism, that is, the intact limb was relied more than the restricted limb. This paper aims to study the effects of unilateral restrictions of the MTP joints on biped robot walking. Gait performance of a biped robot model was analyzed under two conditions, i.e., walking normally, and walking with the MTP joints of the right foot restricted. The results show that unilateral restrictions of the MTP joints lead to larger demands for driving torque and power on partial joints, more total energy consumption, and lower energy efficiency. These results can help understand the functions of the MTP joints in more depth, and offer some inspirations to the researches of biped robots.

PhoB is a response regulator of PhoR/PhoB two-component system from Escherichia coli that is involved in the environmental phosphate regulation. It has been reported that the N-terminal receiver domain (PhoBN) forms a dimer using the α1-α5 face in the apo state and a dimer using the α4-β5-α5 face in the active state investigated by X-ray crystallography. However, it is not clear whether the conformational switch of the dimer is dependent on phosphorylation. Here, we report the NMR studies of PhoBN in solution in its apo form. We observed that the secondary structural fragments of apo PhoBN characterized by NMR are almost the same as those determined by crystallography, but the NMR spectrum of PhoBN shows inhomogeneous amide signals. Concentration dilution experiments and backbone relaxation parameters showed that PhoBN exists in equilibrium between monomer and dimer states. Using paramagnetic relaxation enhancement experiments, we demonstrated that the dimer of apo PhoBN forms several transient dimer interfaces in solution. This finding suggested that, in addition to the monomer-to-dimer exchange, the inactive conformation of PhoBN has different domain arrangements, which are independent of phosphorylation. It provides an experimental data for the conformational selection mechanism of the phosphorylation of PhoBN.

The metatarsophalangeal (MTP) joints play critical roles in human locomotion. Functional restriction or loss of MTP joints will lead to lower walking speed, poorer walking balance, and more consumed metabolic energy cost compared with normal walking. However, existing foot orthoses are focused on maintaining the movement of the ankle joint, without assisting the MTP joints. In this paper, in order to improve the walking performance of people with lower limb impairments, a wearable powered foot orthosis (WPFO) which has actuated MTP joint is designed and constructed. Preliminary experiments on three nondisabled subjects demonstrated functionality and capabilities of the WPFO to provide correctly timed dorsiflexion and plantar flexion assistance at the MTP joint during walking. These results also suggest that the WPFO could offer promise in certain rehabilitation applications and clinical treatment.

The paper studied on the inherent frequency parameters of double branch of the degree of gears alternating meshing impact of planetary transmission system (PTS). The purpose of the research work was to provide the important basis for the optimization design of system response, and then achieved the effect of vibration and noise reduction. Selecting alternating meshing gears parameters could balance the planetary transmission system design objectives, such as load distribution between planetary gears, avoid resonance, and reduce the balance weight of these three design goals, and could be achieved by adjusting the alternating meshing gears parameters of the planetary transmission system. The influence degree of gear meshing stiffness and its torsional stiffness parameters on planetary transmission system was proposed. And the inherent frequencies of vibration modes with varying parameters were analyzed intuitively by modal energy method.

Numerical simulation method (NSM) as an important technique of computational inside fluid machinery complex blade tip clearance leakage flow has been proposed. Clearance leakage and end wall boundary layer and the blade boundary layer interaction makes the tip clearance flow in showing 3D vortex characteristics due to the clearance leakage. Although the geometric size of blade tip clearance compared with the whole flow passage is very small, but it is on the blade passage nearly 20% regional flows, the tip leakage flow will result in the reduction of the tip near the work efficiency, resulting in channel blockage and local losses increase, therefore the correct prediction of the tip leakage flow phenomenon has important significance on further improve the performance of axial flow compressor rotor and expand the stable working range of the rotor.

Long-term evolvement enables human to achieve various locomotion on different terrains. But it is still a challenge for biped robots to walk stably on rough terrain. The purpose of this paper is to develop a lightweight biped robot adaptable to uneven ground, by integrating the inspirations obtained from human into its structure design and realization. The main design concepts of the biped robot include compliance, combination of active and passive actuation, as well as electric-pneumatic hybrid actuation. On this basis, a prototype of the biped robot which is composed of hip joints with unidirectional series elastic actuator, biomimetic knee joints, semi-passive ankle joints and stiffness adjustable feet is developed. Walking experiments on the biped robot shows that it has the ability to adapt to uneven ground with small-sized bumps in maximum height of 8 mm.

High compliant legs are essential for the efficient versatile locomotion and shock absorbency of humans. This study proposes a biped robot actuated by pneumatic artificial muscles to mimic human locomotion. On the basis of the musculoskeletal architecture of human lower limbs, each leg of the biped robot is modeled as a system of three segments, namely, hip joint, knee joint, and ankle joint, and eleven muscles, including both monoarticular and biarticular muscles. Each rotational joint is driven by a pair of antagonistic muscles, enabling joint compliance to be tuned by operating the pressure inside the muscles. Biarticular muscles play an important role in transferring power between joints. Walking simulations verify that biarticular muscles contribute to joint compliance and can absorb impact energy when the robot makes an impact upon ground contact.

Hypochlorite has cytotoxic effect and can provoke the development of a number of chronic inflammatory diseases. A new assay for the assessment of hypochlorite scavenging capacity (HSC), based on the differential pulse voltammetric (DPV) analysis of hypochlorite before and after reduction by dietary antioxidants, was developed. This electroanalytical assay was validated by testing linearity, precision, and accuracy. The calibration curves of antioxidant compounds covering polyphenols, ascorbic acid, and glutathione were investigated, and their response sensitivities and linear concentration ranges were determined. The calibration graph of Trolox (reference compound) was linear with a slope of 6.82 × 10−3 A L mol−1. The limit of detection and limit of quantification for Trolox were 2.55 and 8.50 μM, respectively. Moreover, this method was successfully applied to evaluate the HSC of fruit juices with turbid and colored components. In comparison of popular probe-based methods and hypochlorite scavenging efficacy assay, the proposed DPV method is rapid and better represents the direct scavenging activity of antioxidant samples toward hypochlorite (i.e., the total amount of hypochlorite scavenged by antioxidants). Finally, the chemical meaning of HSC value based on multiple oxidation process (MOS) was analyzed by structural theoretical calculation. It was demonstrated that the proposed DPV-based method is applicable in reflecting the MOS of antioxidants. Overall, the recommended DPV method is simple and enables the direct evaluation of the total hypochlorite scavenging capacity of dietary antioxidants.

Beryllium fluoride is widely used as a phosphoryl analogue in macromolecular studies, which are not only fluoride-sensitive but also magnesium-dependent. The beryllium fluorides are a mixture of different species including BeF3(-) and BeF4(2-) exchanging under thermodynamic equilibrium in neutral aqueous solutions. In the cases of mimicking phosphate group transfer, both beryllium fluoride and the magnesium ion are generally needed. However, the impact of magnesium on the bioactivity of beryllium fluoride is not clear. We have found by (19)F NMR spectroscopy that Mg(2+) can severely affect the chemical exchange kinetics between BeF3(-) and BeF4(2-). When the F(-) concentration is relatively low, the presence of 10.0 mM Mg(2+) can accelerate the exchange rate 3-4 fold. However, when the F(-) concentration is relatively high, the Mg(2+) effect on the chemical exchange vanishes. On the basis of these findings, we proposed a possible mechanism that BeF4(2-) and Mg(2+) form an ion pair that affects the distribution of beryllium fluoride species and thus the activity in the solution.

PhoB is a response regulator of the PhoR/PhoB two-component signal transduction system that is involved in the regulation of the phosphate (Pho) regulon of Escherichia coli. PhoB has two domains, receiver domain and effector domain. The receiver domain can be phosphorylated by its cognate histidine kinase PhoR and the phosphorylation induces conformational changes of the full length protein of PhoB that promote the DNA binding and transcription. Three-dimensional crystal structures of PhoB receiver domain (PhoB

Shellfish allergy is a prevalent, long-lasting disorder usually persisting throughout life. However, the allergen information is incomprehensive in crab. This study aimed to identify a novel allergen in crab, show its potential in diagnosis and reduce the allergenicity by food processing. A 21-kDa protein was purified from Scylla paramamosain and confirmed as sarcoplasmic calcium binding protein (SCP) by matrix-assisted laser desorption ionization-time-of-flight/time-of-flight mass spectrometry (MALDI-TOF/TOF-MS). Total RNA was isolated from crab muscle, and a rapid amplification of cDNA was performed to obtain an ORF of 579 bp that coded for 193 amino acid residues. According to the results of circular dichroism analysis and ELISA assay, the recombinant SCP (rSCP) expressed in Escherichia coli showed similar physicochemical and immunoreactive properties to native SCP (nSCP). Additionally, the extensive cross reactivity of SCP among different species and the bidirectional IgE cross-reactivity between nSCP and rSCP were detected by iELISA. The allergenicity of rSCP was reduced via Maillard reaction or enzymatic cross-linking reaction, which was confirmed by the results of scanning electron microscopy, dot blot, and digestion assay. A straightforward and reproducible way was developed to obtain high yields of rSCP that maintains structural integrity and full IgE reactivity, which could compensate the low specific IgE-titers of most patient sera for future diagnosis. Furthermore, the Maillard reaction and enzymatic cross-linking reaction were effective approaches for the production of hypoallergenic seafood.

The characterization of protein-ligand interaction modes becomes recalcitrant in the NMR intermediate exchange regime as the interface resonances are broadened beyond detection. Here, we determined the 19 F low-populated bound-state pseudocontact shifts (PCSs) of mono- and di-fluorinated inhibitors of the BRM bromodomain using a highly skewed protein/ligand ratio. The bound-state 19 F PCSs were retrieved from 19 F chemical exchange saturation transfer (CEST) in the presence of the lanthanide-labeled protein, which was termed the 19 F PCS-CEST approach. These PCSs enriched in spatial information enabled the identification of best-fitting poses, which agree well with the crystal structure of a more soluble analog in complex with the BRM bromodomain. This approach fills the gap of the NMR structural characterization of lead-like inhibitors with moderate affinities to target proteins, which are essential for structure-guided hit-to-lead evolution.

This paper presents the design and control of a biomimetic knee joint for biped robots. The robotic knee joint driven by pneumatic artificial muscles is designed by imitating the structure of the human knee. It has desirable characteristics similar with human knee joint including joint compliance, changeable instantaneous center of rotation, as well as large range of joint motion. In order to model and compensate the length/pressure hysteresis of pneumatic artificial muscles in the position control, a novel method termed as direct inverse hysteresis modeling approach is introduced. Other than deriving from the forward hysteresis model, the inversion of the length/pressure hysteresis is directly modeled by a modified Prandtl-Ishlinskii model which has two newly-designed play operators. Then a cascade position controller with forward hysteresis compensation is proposed for the knee joint. The mechanical structure and control scheme of the knee joint are validated by experiments.

The under-actuated foot rotation that the heel of the stance leg lifts off the ground and the body rotates around the stance toe is an important feature in human walking. However, it is absent in the realized walking gait for the majority of biped robots because of the difficulty and complexity in the control it brings about. In this paper, a hybrid control approach aiming to integrate the main characteristics of human walking into a simulated seven-link biped robot is presented and then verified with simulations. The bipedal robotic gait includes a fully actuated single support phase with the stance heel supporting the body, an under-actuated single support phase, with the stance toe supporting the body, and an instantaneous double support phase when the two legs exchange their roles. The walking controller combines virtual force control and foot placement control, which are applied to the stance leg and the swing leg, respectively. The virtual force control assumes that there is a virtual force which can generate the desired torso motion on the center of mass of the torso link, and then the virtual force is applied through the real torques on each actuated joint of the stance leg to create the same effect that the virtual force would have created. The foot placement control uses a path tracking controller to follow the predefined trajectory of the swing foot when walking forward. The trajectories of the torso and the swing foot are generated based on the cart-cable model. Co-simulations in Adams and MATLAB show that the desired gait is achieved with a biped robot under the action of the proposed method.

Remote answering system of modern distance education system is an indispensable component. However, the current system is based on answering user input on the exam questions simple keyword matching, accuracy and query the user interface cannot meet the needs of users. We have designed a semantic network theory to build up intelligent answering system. We analyzed the necessity of establishing intelligent answering system, and presents a model of intelligent question answering system based on its technology defined areas, and two university computer courses as a source of knowledge to achieve the function of the system. The results show that the proposed method can improve the accuracy of the query, user-friendly and convenient. System Based on J2EE three-tier system, in the middle layer of the advanced MVC design pattern thought to achieve page display and business logic separation, improve system maintainability.

Whether all dietary polyphenols nourish the eyes via oral supplementation is controversial. Given that passage of dietary polyphenols across the blood-retina barrier (BRB) is the precondition for polyphenols to exhibit ocular benefits, the BRB permeability of polyphenols was assessed in this study. Being common dietary polyphenols in fruits and vegetables, nonanthocyanin flavonoids, anthocyanins, and phenolic acids were investigated. BRB was simulated in vitro by using a differentiated retinal pigment epithelial cell monolayer cultivated on a Transwell culture system. Penetration rate was calculated by quantitatively analyzing the polyphenols in basolateral media. The BRB permeability of different polyphenols obviously (p0.05) differed, as follows: phenolic acidsnonanthocyanin flavonoidsanthocyanins. Glycosylation and methylation improved the BRB permeability of nonanthocyanin flavonoids and anthocyanins. However, instability and carbonylation at the C-4 position severely suppressed the BRB permeability of anthocyanins and nonanthocyanin flavonoids. Moreover, a new metabolite was discovered during penetration of anthocyanins into the BRB. However, hydrophilic phenolic acids exhibited better BRB permeability than hydrophobic ones. Data demonstrate that BRB permeability of polyphenols was determined based on structural characteristics, hydrophilicity, stability, and metabolic changes.

The traditional zero moment point (ZMP) control method is not suitable for underactuated biped robots. In this article, based on the computed torque method, the virtual constraint method and feedback linearization method are introduced into robot control to develop a joint control strategy for a biped robot with flexible ankle joints. Meanwhile, the traditional spline curve planning method of ankle joint and hip joint trajectory is no longer applicable to the biped robot. In this article, the time-invariant gait planning and gait stability of the robot are studied based on the principle of periodic walking. The effectiveness of the control strategy is verified by an experiment on the biped walking robot with flexible ankle joints.

The most common problem for traditional bipedal robots walking on uneven terrain is that the contact area between the soles and ground might reduce because of rigid foot soles, which will force the pose been changed and eventually cause the robots to fall. The pneumatic stiffness-adjustable foot is designed to make the walking more adaptive on uneven terrain. This foot contains a soft sole integrating new supporting airbag units underneath. The stiffness of the airbag units can be changed by internal air pressure and all the units are controlled separately. In the experiment, the interferences are added during the adaptability tests to simulate the uneven terrain and the experimental data shows that the adaptability of the foot can be improved by control of the airbag units' internal pressure.

Beryllium fluorides are widely used in protein phosphorylation studies to get stable transition state analogs or near attack conformers, which has attracted much attention. BeF3- is one of the optimal phosphoryl (PO3-) analogs for its identical geometry and charge, and Mg2+ naturally participates in the phosphoryl binding in biological systems. In solutions, BeF3- coexists with other beryllium fluorides (BeF42-, BeF2 and BeF+) and magnesium fluorides, and there are equilibriums between these species. In this article, F-19 NMR spectroscopy was applied to the investigation of the impact of magnesium(II) on beryllium fluorides. It has been found that when Mg2+ was introduced into the solutions, the chemical shifts, the intensities and the line widths of F-19 signals of various beryllium fluoride complexes were changed. After ionic strength correction, these effects were remarkable only for BeF42- and BeF3-, especially BeF42-, when the concentration of the fluoride ion is relatively low. Mechanism of the effects is proposed which involves ion pair formation between Mg2+ and beryllium fluorides.