纤维聚合物筋与混凝土粘结性能的影响因素

通过 18根 12 0 0mm× 760mm× 40 0mm的混凝土拉拔试件和 64根 12 60mm× 2 40mm× 15 0mm的混凝土梁式试件的试验 ,研究了纤维聚合物筋与混凝土的粘结性能 ,获得了大量的试验结果。以这些试验数据及有关文献报道的相关的试验结果为基础 ,探讨了破坏形式、混凝土强度、锚固长度、纤维聚合物筋直径、混凝土浇筑深度、环境条件等因素对粘结性能的影响。结果表明 ,上述因素对纤维聚合物筋与混凝土的粘结性能有一定的影响 ,在锚固长度等有关的计算中应适当考虑     

Preparing catalytic surfaces for sensing applications by immobilizing enzymes via hydrophobin layers

Simple and reliable immobilization techniques that preserve the activity of enzymes are of interest in many technologies based on catalysis. Here, two redox enzymes, glucose oxidase from Aspergillus niger and horseradish peroxidase, were immobilized by physisorption on glassy carbon electrodes coated with Schizophyllum commune hydrophobin. Hydrophobins are small, interfacially active proteins that have the remarkable property of adhering to almost any surface. We showed recently that these proteins can be used to immobilize small, electroactive molecules. The results obtained in this work show a way to easily manufacture stable, enzyme-based catalytic surfaces for applications in biosensing.     

A comparative trial of the use of saccharose in the treatment of skin lesions in diabetics. Apropos of 80 cases

By establishing appropriate "rules for discussion," it was possible for a diverse group of professionals involved in oral health care to reach agreement on several aspects of defining, confronting, and preventing unethical behavior. A set of specific recommendations is offered, centered in the perspective that patient well-being is paramount.     

A Constructive Globally Convergent Adaptive Speed Observer For Port‐Hamiltonian Mechanical Systems with Non‐Holonomic Constraints

This paper presents an adaptive speed observer for general port‐Hamiltonian mechanical systems with non‐holonomic constraints in the presence of unknown friction forces and constant disturbances. Unlike the observers recently reported in the literature, which have been designed either under the assumptions of no friction and the absence of disturbances or for a specific class of mechanical systems with the requirement of an explicit solution of certain Partial Differential Equations (PDEs) that cannot be derived a priori, this observer proposes a design that obviates the solution of PDEs and ensures global convergence for general mechanical systems with k‐non‐holonomic constraints. The observer is totally constructive and given by explicit expressions. The simulation results testify to the effectiveness and the robust features of the developed observer.     

Modeling the rate of corrosion of carbon steel using activated diethanolamine solutions for CO_2 absorption

A mechanistic model is developed to investigate the influence of an activator on the corrosion rate of carbon steel in the absorption processes of carbon dioxide(CO_2). Piperazine(PZ) is used as the activator in diethanolamine(DEA) aqueous solutions. The developed model for corrosion takes into consideration the effect of fluid flow,transfer of charge and diffusion of oxidizing agents and operating parameters like temperature, activator concentration, CO_2 loading and pH. The study consists of two major models: Vapor–liquid Equilibrium(VLE) model and electrochemical corrosion model. The electrolyte-NRTL equilibrium model was used for determination of concentration of chemical species in the bulk solution. The results of speciation were subsequently used for producing polarization curves and predicting the rate of corrosion occurring at the surface of metal. An increase in concentration of activator, increases the rate of corrosion of carbon steel in mixtures of activated DEA.     

Changes in Lipid Composition and Antioxidant Capacity of Bitter Orange (<Emphasis Type=Italic>Citrus aurantium.</Emphasis> L) and Mandarin (<Emphasis Type=Italic>Citrus reticulata.</Emphasis> Blanco) Oilseeds on Different Stages of Maturity

Oilseeds from bitter orange and mandarin and its antioxidant activities were investigated in this study. The effects of harvesting times (D1: green color, D2 yellow color, D3: orange color) on the extraction yield of oilseed were studied. The maximum yield of 44% was achieved at D3 (bitter orange). The chemical composition of the oilseed was analyzed by gas chromatography (GC). The main methyl esters were linoleic acid (C18:2, 32–42%), palmitic acid (C16:0, 22–26%)), stearic acid (C18:0, 9.01%) and linolenic acid (C18:3, 4–10%). The antioxidant activity of oilseed was assessed by means of 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical-scavenging assay and β-carotene bleaching test. Both methods demonstrated notable antioxidant activities of bitter orange and mandarin oilseeds, which is nearly comparable to the references ascorbic acid and butylated hydroxytoluene (BHT). The antioxidant activities of the oilseeds were also found to be harvesting time-dependent.     

Anisotropic mechanical behavior of semi‐crystalline polymers: Characterization and modeling of non‐monotonic loading including damage

In this work, the mechanical response of high density polyethylene (HDPE) to complex uniaxial tensile loadings is firstly characterized experimentally, taking into account the damage occurring in large deformation and the initial anisotropy induced by the forming process. Anisotropic effects are characterized through tensile tests using several complex loading paths involving large deformation, and for different orientation with respect to the extrusion direction. A mechanical model is then developed, based on a non‐equilibrium thermodynamic approach of irreversible processes, resulting in a new thermodynamic potential describing both the elasto‐viscoelastic–viscoplastic behavior and the volume variation due to damage. Results show that transverse strains and volume strain of HDPE highly depend on specimen orientation, whereas the apparent Young's modulus is not affected by this orientation. The developed model is validated for HDPE, and satisfyingly predicts the complex response of HDPE to complex loadings paths. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44468.     

Study of the combined effect of different types of sand on the characteristics of high performance self-compacting concrete

The characteristics of self-compacting concrete at high performance (SCCHP) made with different types of sand were investigated. Three types of sands were used separately and in binary combinations: river sand (RS), dune sand (DS) and crushed sand (CS). The introduction of CS and DS aims to valorize the by-products of crushing and local materials for the formulation of the SCCHP. Different compositions containing RS, CS, DS and their binary mixtures were experimentally studied. First we started by the measurement of loose compactness’s of different combinations of aggregates and concretes. Thereafter, the SCCHPs were characterized by different test methods such as (slump flow test, L-box test and sieve stability test). Finally, the SCCHPs are subjected to mechanical testing. The obtained results proved that the binary combinations of different sands have a positive effect on the compactness. However, they do not give the best results in rheological and mechanical characteristics of the SCCHP. The results obtained by studying SCCHPs formulated by the addition of CS to the RS with moderate contents (≤40%), and by the addition of DS to the RS at low contents (≤20%) were very interesting from an economic, environmental or technological point of view.     

Carbon dioxide induced degradation of diethanolamine during absorption and desorption processes

Alkanolamines are widely used in the purification of the sourgas sweetening process. During the sour gas absorption process, CO_2 significantly degrades the amine solvent and creates enormous problems for plant operation. In this work, CO_2 induced degradation of aqueous diethanolamine(DEA) solution was conducted in a 1.25 L jacketed glass reactor that functioned as an absorber and stripper at atmospheric conditions. Pure CO_2 was bubbled through the reactor until the solution became saturated. In this study, the concentrations of DEA used were in the range of concentrations between 2 mol·L~(-1) and 4 mol·L~(-1). In the degradation experiment, six generic cycles were conducted for each run. Each cycle was configured with the absorption and desorption of carbon dioxide at 55 ℃ and 100 ℃, respectively. Samples were collected after a predetermined experimental time and analyzed by ion chromatography(IC) to identify unknown ionic degradation products(DGPs). In the IC analysis, three different columns were used for anion, cation and ion exclusion systems, which are Metrosep A Supp 5150/4.0, Metrosep C Supp 4 150/4.0 and Metrosep Organic Acids, respectively. The major identified DGPs of D01 DEA2 M, D02 DEA3 M, and D03 DEA4 M are nitrite, acetate and ammonium. Phosphate product was found in the degraded amine samples which might be due to the contamination of water or chromatographic system.