Differential photoacoustic spectroscopic (DPAS)-based technique for PM optical absorption measurements in the presence of light absorbing gaseous species

In this study, we developed an optical monitor to measure light absorption from particulate matter (PM) at 532 nm using a differential photoacoustic absorption spectroscopic (DPAS) technique. The dual-cell system is capable of measuring the photoacoustic signals due to light absorption of total PM and gaseous samples and that of gaseous samples, separately. The resulting differential photoacoustic signal can be used to determine the light absorption purely from the PM species. This measurement method eliminates the interferences from the light-absorbing gaseous species as well as the surrounding low-frequency background acoustic noises. Photoacoustic signals of the DPAS monitor were calibrated with the NO₂ gas standards, varying from 100 to 250 parts per billion (ppb). Based on an Allan analysis, a detection sensitivity (2σ) of 0.68 Mm^?1 can be achieved in 100 s data acquisition. Using the Jet Burner Test Stand (JBTS) facility at the United Technologies Research Center (UTRC), we measured light absorption by the soot emissions from a representative high-temperature and high-pressure test combustor for aircraft auxiliary power units (APU). The DPAS measurement results at 532 nm, under the high gaseous NO₂ conditions, were then compared to the determination of soot mass concentrations from a commercial AVL Micro Soot Sensor (MSS). An excellent linear correlation between the measurements from two instruments was observed. The mass absorption coefficient (MAC) of the soot using the two data sets was 7.4 ± 1.3 m²g^?1, in good agreement with the previously reported 8.1 ± 1.7 m²g^?1 and the expected value of 7.6 ± 0.6 m²g^?1.

Copyright © 2017 American Association for Aerosol Research     

A critical review of laboratory and in-situ hydraulic conductivity measurements for the Boom Clay in Belgium

The Boom Clay has been investigated for more than 30 years as a candidate host formation for the disposal of high-level and long-lived radioactive waste in Belgium. The very low hydraulic conductivity (on the order of 10^− 12 m/s) in combination with limited hydraulic gradients over the host formation (0.02–0.04) results in water flow in the Boom Formation being negligible and diffusion the dominant transport mechanism. The assessment of the long-term barrier function of the host clay formation in the framework of radioactive waste disposal requires rigorous quantitative characterization of key formation properties such as the hydraulic conductivity (K).Hydraulic conductivities of Boom Clay measured through various testing techniques in the laboratory, i.e. tracer percolation experiments, constant head permeameter experiments and isostatic experiments, exhibit similar K values in the order of 10^− 12 m/s. Based on a large set of test samples, the impact of sample scale, hydraulic gradient range adopted in the tests, stress controlled methods and pre-existing fissures in the sample on the K value is shown to be quite limited. In situ measurements obtained from both several-centimetre long piezometer filters and percolation into a 7-metre long gallery and 21-metre long shaft at the HADES underground research facility yield K values that are very similar to values measured in the laboratory on samples of a few centimetres. This indicates that the K measurements for the Boom Clay obtained through various techniques are very consistent. K values measured on a centimetre-scale are also representative at the metre-scale, which is often the size of grid cells used in numerical simulations for long-term safety assessments.Spatial analysis of K values across the Boom Clay at the Mol site reveals a typical profile with a very homogenous 61-m thick central part, i.e. the so-called Putte and Terhagen Members, which is also the least permeable part of the Boom Clay. The geometric mean of the vertical (K_v) and horizontal (K_h) hydraulic conductivities for the Putte and Terhagen Members at the Mol site are 1.7 × 10^− 12 and 4.4 × 10^− 12 m/s, respectively, with a vertical anisotropy K_h/K_v of about 2.5. Higher K values, but still low (10^− 12 to 10^− 10 m/s), are observed in the more silty zones above and below the Putte and Terhagen Members, i.e. the Belsele–Waas Member and the Boeretang Member, as well as in the double band of the lower Putte Member.A regional analysis of vertical K variability of the Boom Clay in the northeast of Belgium based on test results from five boreholes shows an increase in hydraulic conductivity from the east towards the west. Statistical analyses indicate that the effect of the samples' stratigraphic position on hydraulic conductivity is strongly related to different grain-size characteristics. However, a general K–grain-size model does not explain the geographical differences in K values satisfactorily. Geographical differences can be best explained by different K–grain-size relationships at the different boreholes. The regional variation in K could be attributed in part to porosity, which in turn is related to the burial depth of the clay.     

Study on adhesion strength,thermal creep resistance,and light transmittance of ethylene‐polypropylene copolymer grafted with silane for photovoltaic application

We investigated the possibility of using PP as an encapsulant in a photovoltaic module. PP is inexpensive but shows low adhesion strength to glass (and silicon wafer) due to its nonpolar nature as well as opacity due to its crystalline nature. We resolved these problems by employing metallocene catalyzed ethylene‐propylene copolymer (EPR) and a nucleating agent to increase the transparency. Five EPRs having various propylene/ethylene ratios were investigated. EPRs having higher propylene content showed higher adhesion strength to the glass substrate. However, it is not appropriate to use EPRs with higher propylene content because they show low processability in calendaring processing. We therefore used a blend of two EPRs. The blend of the two EPRs showed somewhat low transparency. When the nucleating agent was incorporated in the blend, the transparency was remarkably increased. The adhesion strength to the glass plate was enhanced by a silane coupling agent. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43464.     

Mass transfer model,preparation and applications of zeolite membranes for pervaporation dehydration:A review

Pervaporation (including vapor permeation) is a kind of new membrane separation technology, possessing the advantages of high efficiency, energy saving and convenient operation. It has promising application in the separation and purification of organic solvents. Dehydration is an important step in the production and recovery of organic solvents. Zeolite membranes have attracted wide attention for pervaporation dehydration due to their high separation performance and good thermal/chemical stability. So far, zeolite membranes have been preliminarily industrialized for dehydration of organic solvents. This paper reviews the recent development of zeolitemembranes for pervaporation dehydration, includingmass transfermodels, preparation and applications of zeolite membranes. The review also discusses the current industrial applications of zeolite membranes and their future development in pervaporation.     

A method for comparing the nucleation ability of PTFE, iPP and sPP on PE

SUMMARY Heterogeneous nucleation is not only a commonly encountered phenomenon of polymer crystallization, but also a fundamentally important research topic for understanding polymer crystallization. Both, polymer epitaxy and transcrystallization are well known mechanisms for surface induced oriented nucleation, but they only have been studied separately with respect to the nucleation abilities of one polymer to another. A new experimental procedure is established to combine transcrystallization and heteroepitaxy of one polymer on two different polymeric substrates. This provides a new way for comparing the relative nucleation onset of one polymer nucleated simultaneously onto two different substrates. Received: 29 April 1999/Revised version: 26 June 1999/Accepted: 26 June 1999     

有机胺吸收二氧化碳的热力学和动力学研究进展

二氧化碳捕集与封存技术（CCS）是针对大气CO₂含量增高导致的全球气候变暖而提出的全球性解决方案。有机胺吸收法作为经济与技术层面最成熟的技术,是实现二氧化碳捕集的重要工艺过程。从有机胺法吸收二氧化碳的基本反应机理出发,系统评述了应用有机胺法吸收捕集CO₂的热力学与动力学性质的研究进展,介绍了不同类型胺溶剂分子结构与CO₂捕集溶解度和反应速度的关系,并对今后CO₂吸收捕集的热力学和动力学的研究方向提出了展望。     

Synthesis, purification and initial structural characterization of octarellin, a de novo polypeptide modelled on the {alpha}/{beta}-barrel Proteins

We have attempted to construct an artificial polypeptide thatfolds like the eight-stranded parallel ß-barrel structures.Our approach consists of repeating eight times a unit peptidedesigned to adopt a ‘ß-strand/-helix’pattern. A first ‘test’ sequence for this structuralunit was deduced from a series of parameters defined after ananalysis of three natural /ß-barrel proteins and includingprincipally the lengths of the secondary structure elements,the /ß packing and the fitting on average Garnierprofiles. The gene encoding this structural unit was synthesized,cloned and expressed in Escherichia coli either as a monomeror as direct repeats of 2–12 units. Preliminary structuralcharacterization of the 7-, 8- and 9-fold unit polypeptidesby circular dichroism measurements indicates the presence ofthe predicted amount of -helix in the three proteins. Furtheranalysis by urea-gradient gel electrophoresis demonstrates that,in the conditions tested, only the 8-fold unit polypeptide formsa compact structure through a cooperative and rapid two-statefolding transition involving long-range molecular interactions.     

Review on application of nanoparticles for EOR purposes: A critical review of the opportunities and challenges

Nanoparticles have already gained attentions for their countless potential applications in enhanced oil recovery.Nano-sized particles would help to recover trapped oil by several mechanisms including interfacial tension reduction, impulsive emulsion formation and wettability alteration of porous media. The presence of dispersed nanoparticles in injected fluids would enhance the recovery process through their movement towards oil–water interface. This would cause the interfacial tension to be reduced. In this research, the effects of different types of nanoparticles and different nanoparticle concentrations on EOR processes were investigated. Different flooding experiments were investigated to reveal enhancing oil recovery mechanisms. The results showed that nanoparticles have the ability to reduce the IFT as well as contact angle, making the solid surface to more water wet. As nanoparticle concentration increases more trapped oil was produced mainly due to wettability alteration to water wet and IFT reduction. However, pore blockage was also observed due to adsorption of nanoparticles, a phenomenon which caused the injection pressure to increase. Nonetheless, such higher injection pressure could displace some trapped oil in the small pore channels out of the model. The investigated results gave a clear indication that the EOR potential of nanoparticle fluid is significant.     

Experimental apparatus for phase behavior study of solvent-bitumen systems: A critical review and design of a new apparatus

A new apparatus for studying the phase behavior of heavy oil and bitumen with different solvents has been tested. It has the capability of determining physical properties, such as density, viscosity, and compositions, of individual phases over a broad range of temperatures and pressures. One of the unique features of this apparatus is that the method of detecting presence of different phases is based on the values of density and viscosity of the phases rather than visual observation. Thus, the applicability of this apparatus is not restricted to fluids that are transparent to visible light. In addition, this apparatus allows taking samples from each phase for further analysis. The other unique feature of the apparatus is that it is designed for an expeditious thermodynamic equilibration using a rocking cell with a free-rolling ball inside which allows the effective agitation. The success of this design relies upon coupling advanced apparatus construction techniques with accurate density and viscosity measurement for phase detection. The experimental apparatus was tested for vapor-liquid, liquid-liquid, and vapor-liquid-liquid equilibrium systems; and, the results are in good agreement with data published in the literature.     

Properties of the Stöber centrifugal aerosol spectrometer at a high sampling flow rate: calibration, resolving power and correction factors for particle losses

A centrifugal aerosol spectrometer designed by Stöber and Flachsbart (1969) was calibrated at a high sampling flow rate (1.91. min⁻¹) for the particle size range 0.2–5 μm and the resolving power was determined. Multiplication factors to correct for particle losses in the aerosol inlet, in the edge layers of the foil and through the exhaust of the spiral duct were determined.     

Thermophysical,environmental, and compatibility properties of nitrate and nitrite containing molten salts for medium temperature CSP applications: A critical review

The production of electric energy from solar radiation is nowadays one of the most investigated and developed “carbon free” technology. A throughout investigation of the ceramics most commonly used as heat transfer fluids and/or heat storage materials for concentrating solar power systems (i.e. alkaline and heart alkaline nitrate/nitrite mixtures) is here reported. The study stems by the need to base materials selection on an accurate and critical knowledge of all their characteristics, including their thermophysical, environmental compatibility, and economic features.At this purpose, a rating criterion have been established, to readily show the advantages and disadvantages of each material, and to highlight which characteristics of the examined materials need to be further investigated and improved. Nitrate/nitrite mixtures have also been compared with other ceramics used for thermal storage, such as solid fillers, liquid metals, other salt mixtures, or phase change materials.     

A world-wide program for the continuous monitoring of solar UV radiation using poly(phenylene oxide) film,and a consideration of results

The use of poly(phenylene oxide) film to monitor UV radiation is demonstrated, and the results from the continuous monitoring of solar UV radiation at 24 sites throughout the world are presented. The global and diffuse measurements from a temperate and from a tropical site are analyzed in detail, and the effects of season and weather conditions on the UV contribution to solar radiation and the relative importance of the diffuse and direct components of solar UV are discussed.     

2001年联合国际耐火材料会议论文摘评Ⅰ:钢铁工业用耐火材料

每两年一度的联合国际耐火材料会议是目前世界上规模最大、影响面最广的国际耐火材料界的学术活动 ,足以反映世界范围耐火材料生产、应用和研发的新动态。本文对 2 0 0 1年 11月在墨西哥举行的第七届该会收入的 15 8篇论文选择性地作了述评。所选内容是作者按自己的见解 ,认为技术上有新颖性、对我国耐火材料技术的发展启发和借鉴意义大者。本期发表的是第一部分 ,是关于钢铁工业用耐火材料方面的 ,主要涉及低蠕变高铝砖、镁碳砖、直接还原铁回转窑衬砖、炉外精炼用无铬耐火制品的组成和性能、钢包衬和高炉出铁沟用浇注料等     

A review on preparation,surface enhancement and adsorption mechanism of biochar-supported nano zero-valent iron adsorbent for hazardous heavy metals

Heavy metal pollution of water is a global concern, which adversely affects human health because of its resistance to biodegradation and thus its transmission in the food chain via bioaccumulation. Nano zerovalent iron (nZVI) is very effective for the removal of heavy metals and is cost effective in terms of production. However, the main problems of nZVI are agglomeration and ease of oxidation. Several stabilization materials have been implemented to limit the aggregation of nZVI, such as silica, activated carbon and biochar. In comparison, as a support material, biochar possesses a large surface area, high stability and strong adsorption capacity, as well as being obtainable from various types of materials. Thus, this work aims to establish the opportunities available on the use of biochar-supported nZVI in utilizing its ability to stabilize and immobilize the nZVI. This review also reports the preparation, modification and surface enhancement of biochar, nZVI and biochar-nZVI for practical use as adsorbents. This review shows that modifications of the nZVI surface can help in their stabilization and reduction of aggregation. Additionally, this review is able to increase one's understanding of heavy metal sorption behavior by biochar-supported nZVI as it is the important as heavy metal sorption is driven based on biochar-nZVI type and heavy metal species which involve numerous mechanisms, including physical binding, complexation, ion exchange, surface precipitation and electrostatic interactions. Furthermore, this research reviews the adsorption parameters, including the crucial adsorption mechanism of heavy metals onto biochar-nZVI; the reusability of the biochar-nZVI is also discussed in this work. © 2022 Society of Chemical Industry (SCI).     

Semi-empirical model of toluene transport in polyethylene membranes based on the data using a new type of apparatus for determining gas permeability, diffusivity and solubility

Solubility, diffusivity and permeability of toluene vapors in low-density polyethylene (LDPE) membranes of various thicknesses (approximately 48, 93, 138 and 187 μm) at different temperatures 30, 40 and 50 °C in the range of relative vapor pressure p/p⁰=(0.05; 0.95) were measured using new type of permeation apparatus. Moreover, special construction of the new cell enables determination of the permeant amount sorbed in the membrane in the steady state operation of vapor permeation.The simple semi-empirical model of toluene transport in a polyethylene membrane based on relation between experimentally obtained effective diffusion coefficients and concentration dependent diffusion coefficients evaluated from experiments on a new permeation apparatus was proposed. The model enables estimation of toluene fluxes, sorption in the steady state of vapor permeation and concentration profiles in a polyethylene membrane from equilibrium sorption isotherms and effective diffusion coefficients. Very good agreement between experimental and calculated values from the proposed model was obtained.     

A study on sulfonated poly(arylene ether sulfone) membranes containing two different types of SiO2 for a high temperature and low-humidified polymer electrolyte fuel cell

Two different types of silica oxide were prepared as filler in sulfonated polymers for fuel cell applications operated under water deficient environment. SiO₂ nanoparticle and thiol-embedded SiO₂ nanoparticles were mechanically mixed with sulfonated (arylene ether sulfone) solutions, and then the mixtures were cast to prepare composite membranes. The composite membranes with different amount of SiO₂ were prepared to investigate the effect of two types of SiO₂ nanoparticles on ionic conductivity with relative humidity at 120 °C. In addition, ion exchange capacity, water uptake, thermogravitational analysis, differential scanning calorimetry were studied. As results, the composite membranes containing thiol-embedded SiO₂ showed better water-channel forming ability at low relative humidity less than 50% in this study. Under full hydration of the composite membranes, the composite membranes containing pure SiO₂ nano-particles have higher ionic conductivity since the thiol-embedded SiO₂ might cause steric hindrance to make water channel well connected. Thus, below 50% relative humidity, the composite membranes containing 10 wt% of thiol-embedded SiO₂ showed the best ionic conductivity. It is very promising for polymer electrolyte fuel cells operated normally under 50% relative humidity at cathode.     

A review of some of the main results of a research on the ageing phenomena of concrete: Effect of moisture conditions on strength,shrinkage and creep of mature concrete

“Dry strengths” were about two thirds higher than “wet strengths”. An increase (a maximum) in compressive strength was obtained in the region of moisture condensation in pores. Very dry drying conditions may cause strength reduction. The shrinkage can be divided into three different parts: very strong between RH 100… 50%, minor or negligible between RH 50…20%, strong between 20… 0%. The creep is greatly dependent on moisture conditions. Carbonation increases creep.     

A kinetic model for evaluating the dependence of the quantum yield of nano-TiO2 based photocatalysis on light intensity, grain size, carrier lifetime, and minority carrier diffusion coefficient: Indirect interfacial charge transfer

A model based on spherical TiO₂ nanoparticles was developed to study heterogeneous photocatalysis based on TiO₂ in the case of indirect interfacial charge transfer. In this model, the effect of light intensity (I₀), grain size (r₀), carrier lifetime (τ_p), and minority carrier diffusion coefficient (D_p) on the quantum yield (QY) of photocatalytic reactions was investigated in detail. Under conditions of sufficiently low incident-light intensity, the QY was found to be ∝I₀, while it decreased rapidly with an increase in I₀. In addition, the QY went to zero at a critically high light intensity. Furthermore, the QY was found to decrease with increasing r₀ due to the bulk-recombination loss, and the effect of r₀ on the QY became increasingly stronger with the increase in I₀. The QY decreased with the decrease in τ_p and D_p, which was more apparent at the critically high I₀. Under conditions of low [(RH₂)_aq], the QY increased with an increase in [(RH₂)_aq], while it remained nearly constant at high [(RH₂)_aq] due to the fact that the photoinduced electron interfacial transfer became the limiting step for photocatalytic reactions in the case of high [(RH₂)_aq].     

Recovery of poly(ethylene terephthalate) (PET) from used X-ray film,part 1. A review of current problems and a chemical method for recovery of silver and PET

Current methods for the recovery and recycling of poly(ethylene terephthalate) (PET), from used X-ray and lithographic films, are described. The principal problems involving initial separation of silver, poly(vinylidene chloride) (PVDC), gelatin, adhesive tape and paper are described, prior to recovery of PET. Structures and physical properties of PVDC and PET are described, and chemical methods for the recovery of silver and PET and techniques for the removal of paper and adhesive tape are given. Quality assessment of recovered PET is by determination of key physical and mechanical properties. Emphasis is placed on the necessity of recovery material of adequate purity, at economical cost, for commercial use.