Search

Chronic mountain sickness (CMS) is a high altitude complication with high rates of morbidity and mortality. CMS is characterized by high-altitude polycythemia (HAPC) and high-altitude pulmonary hypertension (HAPH). In this study, macitentan, a dual endothelin receptor antagonist, was used to treat CMS, and the induced metabolomics changes were studied. CMS was induced in rats in a hypobaric hypoxia chamber (simulating a 5500 m plateau) for 4 weeks. Macitentan was administered in the third and fourth weeks (30 mg·kg-1·day-1). At the end of the follow-up period, we performed echocardiography, measured hemodynamic parameters and hematocrit, and performed histological staining. Furthermore, ultraperformance liquid chromatography-mass spectrometry (UPLC-MS)-based metabolic analysis was applied to explore metabolic changes associated with hypobaric hypoxia, with or without macitentan. qRT-PCR and kits for the determination of xanthine oxidase (XO) activity were used for validation experiments. Macitentan was effective in attenuating CMS, including CMS-induced right ventricle hypertrophy, HAPC, and HAPH. The levels of 48 metabolites were significantly changed in the CMS model group compared to the control group. Of these changes, 21 were reversed by treatment with macitentan. Enrichment analysis revealed that the purine metabolism pathway, as well as the arginine/proline metabolism pathway, might be the key pathways adjusted by macitentan. Furthermore, we verified macitentan played a beneficial role by directly regulating the expression of arginine1 and arginine2 in the arginine/proline metabolic pathway, and the activity of xanthine oxidase in the purine metabolic pathway. In conclusion, this study demonstrated that macitentan significantly ameliorated CMS in rats, and the mechanism was attributed to the reversion of the disorder in purine and arginine/proline metabolism, via direct regulation of XO activity and arginine1/2 expression. These findings are expected to provide new insights into the therapeutics and mechanism of macitentan in CMS.

Hydrogenation of biomass-derived ethyl levulinate (EL) to gamma-valerolactone (GVL) is an important step in the conversion of sustainable biomass resources into value-added chemicals. Exploration of highly efficient and easily obtainable catalysts is crucial for the large-scale application. In this work, a series of cobalt catalysts were prepared by one-step reduction route in different solvents and applied into the conversion of biomass-derived EL to GVL. Common solvents, including water, methanol, ethanol, glycol and glycerin were attempted as the solvent. Both the solvent effect on the catalyst synthesis and the hydrogenation reaction parameters during the conversion of EL into GVL were systematically investigated. The catalysts were characterized by SEM-EDS, TEM, powder XRD, N2 adsorption-desorption, and XPS. The results demonstrated that the solvents had significant influences on the morphology and structure of the as-prepared catalysts, which changed from dendrite (in water) to spheres (in glycerin). All the catalysts prepared in different solvents were effective for the conversion of EL. Under the optimized conditions, a high GVL yield of 91.4% was achieved when using cobalt catalyst prepared in ethanol at relatively mild reaction conditions. Furthermore, the catalyst could be reused at least 6 times without significant loss of the catalytic activity. As far as we know, this is the first work on the application of cobalt catalysts, synthesized by one-step solution phase reduction method, in the conversion of EL into GVL in biomass utilization.

Wood plastic composites (WPCs) are a new generation of green composites which can come mostly from recycled materials. The addition of the flake graphite (FG) fillers has a significant influence on the properties of WPCs and this study focuses on the heat transfer and mechanical properties of WPCs. The thermal conductivity increases with the increase of addition amount of FG and decreases with the increase of temperature. By comparing the temperature changes of specimens during heating and cooling process, WPCs with higher FG contents presents higher average equilibrium temperature. The WPCs adding FG fillers obtain a greater flexural modulus but a lower flexural strength due to the heterogeneous distribution of the stress. In general, the mechanical properties of WPCs decrease slightly with increasing content of the FG.

With the fast depletion of fossil resources, exploring the value-added utilization approaches of low rank coals and promoting the conversion of sustainable biomass resources into useful chemicals are critical topics facing human society. In this work, we attempted low rank lignite as raw materials to construct novel Zr-based catalysts for biomass conversion using the abundant oxygen-containing groups and specific network structures of lignite. Two components of lignite, i.e. humic acids (HA) and the solid residues (SR) after HA extraction, were used to prepare the catalysts. The prepared catalysts were applied into the conversion of biomass-derived ethyl levulinate (EL) to gamma-valerolactone (GVL), an important reaction for the conversion of biomass resources. Both the preparation conditions of the catalysts and the parameters during catalytic reaction process were systematically investigated. The structures of the catalysts were characterized by SEM, TEM, FTIR, powder XRD, and TG analysis. The results demonstrated that the route using lignite as raw materials to construct Zr-based catalysts was feasible, and the designed catalysts were highly efficient for the conversion of EL into GVL. The conversion of EL, GVL yield and selectivity could reach up to >90% under suitable conditions. The catalysts could be used at least 11 recycles without notable changes in both performances and structures, indicating an excellent stability. This work may provide potential ways for both value-added utilization of low rank coals and construction of efficient catalysts for biomass conversion.

As a natural and renewable resource, bamboo is attractive to reinforce thermoplastic due to its excellent mechanical performance. However, it is difficult for long bamboo fiber bundles (LBF) to premix with thermoplastic pellets and could not fluently feed into screw extruder because of its tendency to entangle. To address this challenge, a new method for premixing and feeding LBF and thermoplastic matrix was initially proposed. The polypropylene (PP) film was used as a carrier to wrap long bamboo fibers (about 120mm long), and the PP roll that enclosed the bamboo fibers was fed into and compounded by a twin rotor. The extruded mixture was finally hot-pressed into plates. The compounding process was monitored and analyzed. The fiber size measurements showed that the rotor with a smooth arris and less arris number reduced the damage to LBF. The optimal LBF distribution and orientation in the PP matrix was obtained when the LBF content was arranged at 40 %. The LBF/PP composite achieved the improved tensile strength and modulus, increasing by 54.44 % and 39.67 %, respectively, compared to the composite reinforced with the traditional bamboo powder. Also, LBF reduced the thermal expansion of the composite by 39.25 %. In terms of water absorption deformation and thermal degradation, no significant difference was found between the two composites at the same fiber contents. Dynamic mechanical tests and dynamic oscillatory rheological tests indicated that the LBF restricted PP movement more than short fibers and showed higher modulus, loss coefficient and complex viscosity. The results indicated that wrapping fibers with thermoplastic film is a promising approach for extruding long fiber reinforced thermoplastic composites, which provides potential applications of LBF in the fields of thermoplastic prepreg.

Surface sediments were collected from 122 sites in the upstream of the Yellow River, China. The concentration of Fe, Mn, Cu, Ni, Zn, Cr, Pb, and Cd in sediments was investigated to explore the spatial distribution based on statistics and interpolation method. The results suggested that the concentrations of heavy metals were lower than potential effect levels (PEL). The samples above threshold effect level (TEL) for Pb and Zn were less than 10%, while almost 50% of samples for Ni exceeded PEL. Pb and Zn in sediments performed little or no adverse effects on the aquatic ecosystems. Higher concentrations of all heavy metals occurred in Qinghai and Gansu sections; the concentrations of Cu, Ni, and Zn were significantly higher than the Inner Mongolia section. Lower concentration of Fe, Mn, Cu, Ni, and Zn appeared in Qinghai section; the concentrations of Fe, Mn, Cr, and Pb manifested relatively steady and similar distributions and approximately decreasing tendency along the upstream of Yellow River.

A novel bipolar photon-controlled generalized memristor model with an avalanche photodiode (APD) passive quenching circuit is presented in this paper. The SPICE model of the circuit is established and its fingerprints are analyzed by the pinched hysteresis loops with different bipolar periodic stimuli. The dynamical characteristics of the proposed circuit model are investigated both theoretically and simulatively. The results verified by Cadence Spectre circuit simulator demonstrate that the proposed circuit model is a simple bipolar photon-controlled generalized memristor. Compared with the previously published memristor models, the biggest innovation of this paper is to propose a bipolar generalized memristor model instead of the traditional model, which can easily form the pinched hysteresis loop. Another highlight is that the generalized memristor model in this paper is controlled by photons while conventional memristors are charge-controlled/flux-controlled. Furthermore, the circuit level models are more stable, more reliable and more resistant to interference than the device level models. The topological structure of the proposed circuit model in this paper is much more simpler.

Preparation of natural fiber-reinforced thermoplastic prepreg tapes is impeded by two major challenges: 1) incompatibility between natural fibers and thermoplastic; and 2) difficulty impregnating thermoplastic into fibers, due to thermoplastics’ high viscidity. In this study, we investigated the reaction mechanisms associated with jute twines that were treated with alkali and laccase, to improve the compatibility of jute twine/ polypropylene (PP) tape. Simultaneously, PP with three melt flow indices (MFI, 10.9 g/10 min, 27.8 g/10 min, 50.0 g/10 min) was tested to determine optimal conditions for PP impregnation. The results showed that alkali and laccase treatment can effectively improve the interfacial bonding strength between jute twine and PP; although laccase treatment is milder than alkali treatment, and thus enabled more improvement in the prepreg tapes’ tensile and dynamic mechanical properties. The amount of PP impregnated into the jute twine increased as a function of increasing MFI. However, the impregnation effect must be balanced with the PP’s tensile strength. In summary, the prepreg tapes prepared by laccase-treated jute twine and PP with an MFI of 27.8 g/10 min exhibited the best tensile performance. Based on subsequent calculations, the nominal pressure of a pipe wound with laccase-modified jute twine prepreg tapes, can reach 2.88 MPa.

Maintenance of genome integrity is critical for faithful propagation of genetic information and the prevention of the mutagenesis induced by various DNA damage events. RecQ-mediated genome instability protein 1 (RMI1), together with Bloom syndrome protein and topoisomerase IIIα, form an evolutionarily conserved complex that is critical for the maintenance of genomic stability. Herein, we report that RMI1 depletion increases cell sensitivity to camptothecin treatment, as shown by an elevation of genotoxic stress-induced DNA double-strand breaks, a stronger activation of the DNA damage response, and a greater G2/M cell cycle delay. Our findings support that, upon DNA damage, RMI1 forms nuclear foci at the damaged regions, interacts with RAD51, and facilitates the recruitment of RAD51 to initiate homologous recombination. Our data reveal the importance of RMI1 in response to DNA double-strand breaks and shed light on the molecular mechanisms by which RMI1 contributes to maintain genome stability.-Fang, L., Sun, X., Wang, Y., Du, L., Ji, K., Wang, J., He, N., Liu, Y., Wang, Q., Zhai, H., Hao, J., Xu, C., Liu, Q. RMI1 contributes to DNA repair and to the tolerance to camptothecin.

A large amount of almond shells are disposed of every year. The anatomical and chemical characteristics of almond shells are investigated in this paper in order to contribute to better utilization of these shells. The micromorphology, surface elements, thermal stability, crystallization, chemical composition, and relative properties of almond shells are analyzed. Under observation by microscope and electron microscope, the diameter of almond shells is 300&ndash, 500 &mu, m for large holes, and 40&ndash, 60 &mu, m for small holes present in the shell. X-ray photoelectron spectroscopy shows the elements of almond shells include C (72.27%), O (22.88%), N (3.87%), and Si (0.87%). The main chemical constituents of cellulose, hemicellulose and lignin in almond shells account for 38.48%, 28.82% and 29.54%, respectively. The alkaline extract content of almond shells is 14.03%, and benzene alcohol extraction is 8.00%. The benzene alcohol extractives of almond shells mainly contain 17 types of organic compound, including benzene ring, ethylene, carbon three bond, and other mufti-functional groups. Thermal stability analysis shows almond shells mainly lose weight at 260 &deg, C and 335 &deg, C. These characteristics indicate that almond shells have the capacity to be used in composites and absorption materials.

In this study, high-density polyethylene (HDPE)/wood-flour composites with a basalt fiber (BF)-reinforced shell were prepared by coextrusion. After exposing these composites to ultraviolet weathering for 2000 h, their performances were examined from their measurements of color, surface morphology, and chemical properties. As a control, UV326 was also added to the shell formula. The weathered surface was characterized by scanning electron microscopy, Fourier transform infrared (FTIR) spectroscopy, and X-ray photoelectron spectroscopy. The results revealed that the shells filled with 8% and 12% BF exhibited low lightness and color change in comparison to those filled with UV326 for a limited duration. The composite shells with the combined BF and UV326 exhibited the least discoloration and surface cracks. FTIR spectra revealed that the oxidation of the composites increases with the duration of exposure to the assessment of the carbonyl group concentration on the surface. The combination of BF and UV326 revealed a synergistic effect on the alleviation of the photooxidation of wood-plastic composite shell layers, verifying the UV-shielding effect.

In this study, a pulp beating machine was used to premix the pulp fibers with high density polyethylene (HDPE) particles in water. The wet or pre-dried pulp fiber/HDPE mixture was then melt-compounded by a twin screw extruder. For further improving the dispersion of pulp fiber, some mixture was forced to pass through the twin-screw extruder twice. The resulting mixture was compression molded to the composite. The fiber distribution was observed by the aid of an optic and scanning electron microscope. The mechanical and rheological properties and creep resistance of the composites were characterized. Test results demonstrate that when the wet pulp fiber/HDPE mixture was subjected to pre-pressing and oven drying prior to extrusion compounding, the resulting composites exhibited homogeneous fiber distribution, superior flexural property, creep-resistance, and high storage modulus. Particularly, its flexural strength and modulus were 57% and 222% higher, respectively, than that of the neat HDPE, while the composites prepared without pre-dried were 19% and 100% higher, respectively. Drying the wet mixture in advance is more effective than re-passing through the extruder for improving the fiber dispersion and composite performance.

Wood Plastic Composites (WPCs) are a new generation of green composites that could optimize the use of harvested trees and increase the entire value chain. In this study, the electrical and mechanical properties of WPCs containing carbon blacks (CB), flake graphite (FG) and carbon nanotubes (CNTs) have been investigated. The electrical property of WPCs is improved significantly owing to the introduction of these carbon nanomaterial fillers. The volume and surface resistivity values of the investigated composites all obviously decreased with the increase in filler content, especially CNTs, which displayed the most satisfactory results. Based on a series of laboratory experiments carried out to investigate the mechanical performance, it can be concluded that the addition of the carbon nanomaterial fillers decreases the mechanical properties of WPCs slightly with the increase in filler content because of the weak interfacial interactions between the fillers and polymer matrix.

An efficient bifunctional NbOPO4 supported Ru catalyst (Ru-NbOPO4) was applied to the hydrodeoxygenation of aromatic ethers and phenols and the upgrading of bio-oil. Characterization results revealed that the Ru-NbOPO4 catalyst possessed strong acidity, including Lewis and Bronsted acids. The Lewis acid sites originated from the Nb O bonding structures, including slightly distorted octahedral NbO6, regular tetrahedral NbO4 and highly distorted octahedral NbO6. In combination with the strong acidity of the Nb O species and excellent hydrogenation activity of the metallic Ru, the bifunctional Ru-NbOPO4 catalyst exhibited an excellent catalytic activity in the hydrodeoxygenation of aromatic ethers and phenols with different structures, and even real bio-oil to alkanes. The hydrocarbon yield after real bio-oil upgradation was up to 88.2 %. Carbon deposition and enlargement of the Ru nanoparticles resulted in slight deactivation of the catalyst. The catalytic activity could be mostly recovered after being calcined and reduced.

The defects of creep deformation and brittle fracture, which coexist in wood plastic composites (WPCs), significantly restrict WPCs as structural engineering materials. This study aims to advance WPCs via structural design and co-extrusion technology, for the development of a lightweight, high-strength, tough, creep-resistant, and water-resistant composite, for structural engineering applications. Novel wood-plastic/lumber composites (WPLCs) were fabricated with high-strength lightweight laminated veneer lumber (LVL) as a core and water-resistant wood-polyvinyl chloride composites (WPVCs) as the shell layer using multi-phase co-extrusion technology. The effect of wood content in the shell layer on flexural properties, impact strength, low-velocity impact behavior, creep resistance, and dimensional stability of the WPLCs were investigated and compared with those of LVL and WPVCs. Increasing wood content within the scope of the experiment resulted in increased flexural strength and modulus in both WPVCs and WPLCs. The flexural modulus and impact strength of WPLC containing 60 phr wood in shell layer (WPLC60) were significantly increased by 112.8% and 303.6%, respectively, compared with that of the corresponding WPVC60 control. Factoring in composite density, the comparison between WPLCs and WPVCs showed specific flexural modulus and impact strength of WPLC60 as 284% and 704% of the values of WPVC60, respectively. The WPLCs exhibited higher impact resistance and bending stiffness and lower absorbed energy and permanent indentation than those of LVL. The creep strain of the WPLCs decreased with increasing wood content in the shell layers. Specifically, the creep strain of WPLC60 was 85.8% and 28.9% of the values of LVL and WPVC60, respectively. The WPLCs almost kept their original appearance except for discoloration after nine cycles of hot water immersion. The water absorption and thickness swelling of the WPLCs were below 1.0% and considerably lower than those of the LVL and pure PVC co-extruded samples. The experimental results indicated that the novel co-extruded wood-plastic/lumber composites effectively achieved excellent performance suitable for structural engineering applications.

In this paper, we present an algorithm for reversal median problem whose performance ratio is less than 2.

We study genome rearrangements by reversals and present a modified lower bound and an almost holding upper bound for this problem.

In order to read a DNA sequence, we propose a method which induces the concept of DNA graph. In this paper, by discussing the adjoints of DNA graphs, we obtain more DNA graphs from known DNA graphs.

The problem studied in this paper is to determine E(p,C), the maximum size of a connected graph G with the given vertex number p and cutwidth C. This paper presents some results on this problem.

edge of graph G, the distance between x and uv is defined as follows: d(x, uv) = min{ d(x, u), d(x, v) }, where d(x, u) is the length of the shortest path that connects x and u in G. For uv∈E(G), let mu = |{ f∈E(G): d(u, f) < d(v, f) }|. GA3 index is a possible tool for QSAR/QSPR researches and it gives somewhat better predictions than those of GA2 does [1, 2]. In this paper we study the third geometric-arithmetic index of TUC4C8(S) nanotorus. For the figure of TUC4C8(S) nanotorus, see [3].

We consider the problem of finding a feasible flow in a directed networkG = (N,A) in which each nodei ź N has a supplyb(i), and each arc(i,j) ź A has a zero lower bound on flow and an upper bounduij. It is well known that this feasibility problem can be transformed into a maximum flow problem. It is also well known that there is no feasible flow in the networkG if and only if there is a subsetS of nodes such that the net supplies of the nodes inS exceeds the capacity of the arcs emanating fromS. Such a setS is called a"witness of infeasibility" (or, simply, awitness) of the network flow problem. In the case that there are many different witnesses for an infeasible problem, a small cardinality witness may be preferable in practice because it is generally easier for the user to assimilate, and may provide more guidance to the user on how to identify the cause of the infeasibility. Here we show that the problem of finding a minimum cardinality witness is NP-hard. We also consider the problem of determining aminimal witness, that is, a witnessS such that no proper subset ofS is also a witness. In this paper, we show that we can determine a minimal witness by solving a sequence of at mostn maximum flow problems. Moreover, if we use the preflow-push algorithm to solve the resulting maximum flow problems and organize computations properly, then the total time taken by the algorithm is comparable to that of solving a single maximum flow problem. This approach determines a minimal cardinality witness in O(n2m1/2) time using simple data structures and in O(nm logn) time using the standard implementation of the dynamic tree data structures. We also show that the recognition version of the minimal witness problem is equivalent to a recognition version of a related problem known as theminimum rooted cut problem. © 1998 The Mathematical Programming Society, Inc. Published by Elsevier Science B.V.

The maximum capacity augmentation algorithm is a variant of the Ford-Fulkerson labeling method in which each flow augmentation is along an augmenting path that yields the maximum increase in flow value. For networks with integer capacities this algorithm has been shown to be polynomial but not to be strongly polynomial, while for networks with real capacities it has been shown that it may require an infinite number of iterations. In this paper, we present two modified versions of the maximum capacity augmentation algorithm which we prove to be strongly polynomial even for real capacities. One of these is a simplex variant.

We present two variants of the primal network simplex algorithm which solve the minimum cost network flow problem in at mostO(n 2 logn) pivots. Here we define the network simplex method as a method which proceeds from basis tree to adjacent basis tree regardless of the change in objective function value; i.e., the objective function is allowed to increase on some iterations. The first method is an extension of theminimum mean augmenting cycle-canceling method of Goldberg and Tarjan. The second method is a combination of a cost-scaling technique and a primal network simplex method for the maximum flow problem. We also show that the diameter of the primal network flow polytope is at mostn 2 m.