The main purpose of this research is formulating and optimizing a new road-marking paint which is an environmentally friendly product. This paint is produced with an emulsion of an acrylic copolymer and contains the least of the volatile organic compounds. The formulation and optimization procedure is carried out on the base of experimental design by the method of mixture in which the important paint properties are modeled by using special cubic model. The present method has the capability of investigation the effect of raw materials at different levels with fewer experiments than factorial and fractional factorial design.
In this research, the main parameters such as resin, pigment and filler were selected at different levels, and different samples were prepared by combination of additives and other required reagents. The properties of wet and dry films of the samples were determined using ASTM test methods. Different responses such as pigment volume concentration (PVC), latex critical pigment volume concentration (LCPVC), abrasion resistance, hardness, gloss, no pick up time and surface drying time, were selected as the objective functions of this study. By running DX6 software, using special cubic model and selection of desired range of end-use properties, the region of optimum paint formula was determined.
The accuracy of the model was examined by preparing a sample in optimized region and by determining its final properties, experimentally. The results exhibit a good agreement between the model and experimental measurements. This product was compared with commercial solvent based traffic paint and good quality was reported in end-use properties. 相似文献
In the framework of the European COST 507 project the specific heat capacities of aluminium alloys and metal matrix composites based thereon have been measured between 20 and 520 °C by differential scanning calorimetry and stored in the databank THERSYST along with other thermophysical properties mainly drawn from literature. The curves show the influence of additional elements and reinforcements, of the fabrication process, thermomechanical treatment and scanning rate on the precipitation and dissolution kinetics of the various metastable phases and their relative amounts. The database may be used to select existing light alloys or elaborate new ones in view of specific technical applications.Dedicated to Professor Dr. Hans Löffler on the occasion of his 72nd birthday. 相似文献
This study further tested an associative-deficit hypothesis (ADH; M. Naveh-Benjamin, 2000), which attributes a substantial part of older adults' deficient episodic memory performance to their difficulty in merging unrelated attributes-units of an episode into a cohesive unit. First, the results of 2 experiments replicate those observed by M. Naveh-Benjamin (2000) showing that older adults are particularly deficient in memory tests requiring associations. Second, the results extend the type of stimuli (pictures) under which older adults show this associative deficit. Third, the results support an ADH in that older adults show less of an associative deficit when the components of the episodes used are already connected in memory, thereby facilitating their encoding and retrieval. Finally, a group of younger adults who encoded the information under divided-attention conditions did not show this associative deficit. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
The aim of this work is to optimize the different parameters for realization of an absorbing cavity to measure the incident absolute laser energy. Electrochemical oxidation is the background process that allowed the copper blackening. A study of the blackened surface quality was undertaken using atomic force microscopy (AFM) analysis and ultraviolet-visible-infrared spectrophotometry using a Shimadzu spectrophotometer. A two-dimensional and three-dimensional visualization by AFM of the formed oxide coating showed that the copper surfaces became porous after electrochemical etching with different roughness. This aspect is becoming more and more important with decreasing current density anodization. In a 2 mol L-1 of NaOH solution, at a temperature of 90°C, and using a 16 mA cm2 constant density current, the copper oxide formed has a reflectivity of around 3% in the spectral range between 300 and 1,800 nm. Using the ‘mirage effect’ technique, the obtained Cu2O diffusivity and thermal conductivity are respectively equal to (11.5 ± 0.5) 10 to 7 m2 s-1 and (370 ± 20) Wm-1 K-1. This allows us to consider that our Cu2O coating is a good thermal conductor. The results of the optical and thermal studies dictate the choice of the cavity design. The absorbing cavity is a hollow cylinder machined to its base at an angle of 30°. If the included angle of the plane is 30° and the interior surface gives specular reflection, an incoming ray parallel to the axis will undergo five reflections before exit. So the absorption of the surface becomes closely near 0.999999. 相似文献
A new brachytherapy (125)I source has been investigated at Iranian Agricultural, Medical and Industrial Research School. Dosimetric characteristics [dose-rate constant Λ, radial dose function g(l)(r) and anisotropy function F(r,)] of IRA-(125)I were theoretically determined in terms of the updated AAPM task group 43 (TG-43U1) recommendations. Versions 5 and 4C of the Monte Carlo radiation transport code were used to calculate the dosimetry parameters around the source. The Monte Carlo calculated dose-rate constant of the (125)I source in water was found to be 92×10(-4) Gy h(-1) U(-1) with an approximate uncertainty of ±3 %. Brachytherapy seed model, 6711-(125)I, carrying (125)I radionuclides, was modelled and benchmarked against previously published values. Finally, the calculated results were compared with the published results of those of other source manufacturers. 相似文献
The selection of green building materials and products is by far the most controversial task in sustainable construction. Determining the merits of building materials and products in terms of their recycling value, which seems to be a simple matter, is a very controversial topic in building assessment systems. This paper suggests a method to assess energy savings by recycling building materials, which can be a potential indicator of recycling worth. The method takes account of material selection, construction and deconstruction technologies, and the frequency of recycling. The result of this study can be used in assessment tools as a factor separate from the embodied energy. Since embodied energy affects the potential recycling energy, another factor is defined, based on these two factors, in order to make it possible to compare and select materials correctly, based on their embodied energy and recycling potential. 相似文献
Neutrophils, also known as polymorphonuclear leukocytes (PMNs), form a significant component of the innate host response, and the consequence of the interaction between the oral microbiota and PMNs is a crucial determinant of oral health status. The impact of radiation therapy (RT) for head and neck tumour (HNT) treatment on the oral innate immune system, neutrophils in particular, and the oral microbiome has not been thoroughly investigated. Therefore, the objective of this study was to characterize RT-mediated changes in oral neutrophils (oPMNs) and the oral microbiome in patients undergoing RT to treat HNTs. Oral rinse samples were collected prior to, during and post-RT from HNT patients receiving RT at Dental Oncology at Princess Margaret Cancer Centre. The oPMNs counts and activation states were analysed using flow cytometry, and the oral microbiome was analysed using 16S rRNA gene sequencing. Statistically significant (p < 0.05) drops in oPMN counts and the activation states of the CD11b, CD16, CD18, CD64 and H3Cit markers from pre-RT to post-RT were observed. Moreover, exposure to RT caused a significant reduction in the relative abundance of commensal Gram-negative bacteria and increased the commensal Gram-positive microbes. Ionizing radiation for the treatment of HNTs simultaneously decreased the recruitment of oPMNs into the oral cavity and suppressed their activation state. The oral microbiome composition post-RT was altered significantly due to RT which may favour the colonization of specific microbial communities unfavourable for the long-term development of a balanced oral microbiome. 相似文献
In the last couple of years, there Has been an increased interest among the statisticians to define new families of distributions by adding one or more additional parameter(s) to the baseline distribution. In this regard, a number of families have been introduced and studied. One such example is the Marshall-Olkin family of distributions that is one of the most prominent approaches used to generalize the existing distributions. Whenever, we see a new method, the natural questions come in to mind are (i) what are the genesis of the newly proposed method and (ii) how did the proposed method is obtained. No doubt, the Marshall-Olkin family is a very useful method and has attracted the researchers. But, unfortunately, the authors failed to provide the explanation about the genesis of the method that how this family of distributions is obtained. To address this issue, in this article, an attempt Has been made to provide a straight forward computation about the genesis of the Marshall-Olkin family that somehow completes its derivation. The genesis of the Marshall-Olkin family is based on the T-X family approach. Furthermore, we have showed that other extensions of the Marshall-Olkin family can also be obtained via the T-X family method. Finally, a real-life application form insurance science is presented to illustrate the newly proposed extension of the Marshall-Olkin family. 相似文献
Two types of chromium catalysts bearing pyridine and amine based SNS ligands under the title of (pyridine-SNS-alkyl/CrCl3) and (amine-SNS-alkyl/CrCl3) were synthesized. Different thiolates such as octyl, pentyl, butyl, cyclohexyl and cyclopentyl thiolates were reacted with 2,6-pyridine-dimethylene-ditosylate (PMT)/THF solution at room temperature. Then, the purified pyridine-based SNS ligands (1–5) were reacted with CrCl3 (THF)3 to obtain the pyridine-SNS-alkyl/CrCl3 catalysts (6–10) in 50–70% yields. MMAO-activated pyridine-SNS-alkyl/CrCl3 catalysts were capable of oligomerizing ethylene. Statistical experimental design was conducted using the central composite design method and surface methodology to study of the effect of important parameters such as ethylene pressure, Al/Cr ratio, catalyst concentration and the reaction temperature on 1-C6 productivity of catalyst (7). A quadratic polynomial equation was developed to predict the 1-C6 productivity. Ethylene oligomerization using the catalyst (7) was lead to a optimized reaction conditions, including the ethylene pressure of 19.5 bar, the temperature of 58.2 °C, the MMAO co-catalyst, Al/Cr?=?841 and the catalyst concentration of 8.7 µmol. The catalytic properties for ethylene oligomerization are strongly affected by reaction temperature. The experimental results indicated the reasonable agreement with the predicted values. The transformation from ethylene trimerization to ethylenev polymerization of catalyst system (7) was occurred by exchanging the reaction pressure. Influence of ligand structure with different substitutions on sulphur atom on productivity and selectivity was investigated. 1-C6 with the high selectivity and productivity 4318 (g 1-C6/g Cr h) was obtained for catalyst (7). In the second part, 1-C6 was obtained with high selectivity and productivity around 141?×?103 (g 1-C6/g Cr h) for amine-based catalyst. All amine-based catalysts (14–16) showed considerably higher catalytic activities compared to pyridine-based catalysts. According to the TGA analysis the thermal stability of pyridine-based catalysts was found to be higher than the amine-based catalysts.
Graphical Abstract
Chromium complexes bearing pyridine and amine based SNS ligands have been synthesized and their catalytic performance in ethylene oligomerization has been investigated. A switching from ethylene trimerization to ethylene polymerization of the catalyst (7) was obtained utilizing exchanging of the ethylene pressure.