Papers by Keyword: Selectivity

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Authors: Hao Zhang, Xi Jiang
Abstract: The recognition and sensing of biologically and environmentally important species has emerged as a significant goal in the field of chemical sensors in recent years1. Fluorogenic methods in conjunction with suitable probes are preferable approaches for the measurement of these analytes because fluorimetry is rapidly performed, is nondestructive, is highly sensitive, is suitable for high-throughput screening applications2,3. We synthesized rhodamine derivatives compounds by a Schiff base reaction.
Authors: Hua Zhang Liu, Xia Zhen Yang, Ya Qing Cen, Hao Dong Tang
Abstract: The performance and stability for FTS was studied on novel Fe1-xO-based iron catalyst (FIC) in agitated slurry reactor (ASR) and fixed bed reactor (FBR), and compared with precipitation-iron catalyst (PIC). The studied results indicate that novel Fe1-xO-based iron catalyst has the high conversion and high stability, especially, the high alkene selectivity in C2 ~ C4 products that the ratios of olefines and paraffines the more than 9 and the low cost, the preparation process and the high mechanical intensity. The catalyst can be used at FBR or ASR, and FTS at high temperature or low temperature.
Authors: Yong Ling Li, Yu Meng, Ying Shu Liu, Xiong Yang, Chuan Zhao Zhang
Abstract: Enrichment of ventilation air methane(VAM) is crucial to gather acceptable concentration to utilize. In this work, the adsorption characteristics of activated carbon have been tested. A novel three-bed VPSA cycle for recovering methane from methane/nitrogen mixtures using activated carbon have been done experimentally, and the VPSA process studied contains an effluent pressurization step to improve product concentration and recovery. The VPSA process was carried out under adsorption pressure at 155 kPa abs., and desorption pressure at 20 kPa abs., feeding VAM with the methane purity of 0.2%, methane purity of 0.4% with 70% recovery was obtained at ambient temperature while 0.36% purity with 87% recovery. This process has the potential of significantly increasing the product concentration and recovery with respect to the two-bed cycle process by VPSA.
Authors: Marjan Farnam, Hilmi Mukhtar, Azmi Mohd Shariff
Abstract: Polymeric membranes are widely used for gas separation purposes but their performance is restricted by the upper bound trade-off discovered by Robeson in 1991. The polymeric membrane can be glassy, rubbery or a blend of these two polymers. This review paper discusses the properties of glassy polymer membranes and their performance in gas separation. The area of improvement for glassy membrane with development of mixed matrix membrane is also highlighted.
Authors: Mark Robson, Kristin A. Fletcher, Ping Jiang, Michael B. Korzenski, A. Upham, T. Haigh Jr., Thomas J.C. Hsieh
Abstract: In semiconductor processing, test wafers are used as particle monitors, film thickness monitors for deposition and oxide growth measurements, dry/wet etch rate monitors, CMP monitors, as well as characterizing new and existing equipment and processes. Depending on fab size and capacity, monthly test wafer usage can be tens of thousands or more. Due to the ever increasing demand for silicon between the IC and solar markets and the high cost of 300mm wafers, chip manufacturers are increasing their efforts to reduce overall spending on silicon - currently by far the largest non equipment related cost [1]. One approach taken by many chip makers is the concept of extending the usable life of test wafers by re-using them as many times as possible through a reclaim process.
Authors: Siti Khatijah Jamaludin, Ku Halim Ku Hamid, Hazimah Abu Hassan, Ayub Md Som, Zulina Maurad, Azlinda Azizi
Abstract: Dihydroxystearic acid (DHSA) is perceived to be of significant value to various types of industries, especially the oleochemical industry. It is produced by reacting palm-based crude oleic acid (OA) with formic acid and hydrogen peroxide through the in situ epoxidation-dihydroxylation, a multistep reaction process. Optimization of the reaction’s operating conditions with respect to the selectivity of DHSA was conducted via the Taguchi method of optimization. The selectivity of DHSA was determined based on gas chromatography (GC) analysis. The signal-to-noise (S/N) ratio analysis procedure in Taguchi method revealed that the optimum operating conditions for the production of crude DHSA with respect to its selectivity were found to be: catalyst (sulphuric acid) loading at 0.5 gm, formic acid-to-oleic acid unsaturation mole ratio of 1:1, hydrogen peroxide-to-oleic acid unsaturation mole ratio of 0.75:1 and reaction temperature: 85°C. ANOVA tested at 90% confidence level revealed that reaction temperature and catalyst loading highly affect the selectivity of DHSA. The selectivity of DHSA was improved to 97.2% by applying the optimum operating conditions as obtained by Taguchi method.
Authors: John Papalia, Nathan Marchack, Robert Bruce, Hiroyuki Miyazoe, Sebastian Engelmann, Eric A. Joseph
Abstract: Over the course of the past few years, the semiconductor industry has continued to invent and innovate profoundly to adhere to Moore’s Law and Dennard scaling. At each of the technology nodes starting with 45nm, new materials and integration techniques, such as high-K & metal gates, double patterning techniques, and now 3D FinFet / Trigate device geometries are being introduced in order to maintain device performance. This places a large burden on unit process development to accommodate and deliver advanced process capability and is growing the need for the ultimate etch solution: etching with atomic layer precision. Atomic layer etching is a promising path to answer the processing demands of thin high mobility channel devices on the angstrom scale. Self-limiting reactions, discrete reaction & activation steps, or extremely low ion energy etch plasmas are some of the pathways being pursued for precise sub-nanometer material removal. In this invited paper, previously published in SPIE, the ability to achieve atomic layer etch precision is reviewed in detail for a variety of material sets and implementation methods. For a cyclic approach most similar to a reverse ALD scheme, the process window to achieve a truly self-limited atomic layer etch process is identified and the limitations as a function of controlling the adsorption step, the irradiation energy, and the reaction process are examined. Alternative approaches, including processes to enable pseudo-ALE precision, are then introduced and results from their application investigated. While these new plasma-enhanced atomic layer etch (PE-ALE) processes show encouraging results, most patterning applications are best realized by optimizations through discharge chemistry and/or plasma parameters. Significant improvements however were obtained when applying PE-ALE approaches to small pitch patterns. In particular the increased selectivity to OPL seems to offer a potential benefit for patterning high aspect ratio features.
Authors: I. Smičiklas, A. Onjia, J. Marković, S. Raičević
Abstract: Apatites are well known matrix for heavy metal immobilization and remediation of ground water and contaminated soils. In this work, capacities of different synthetic hydroxyapatite (HAP) samples for Pb, Cd, Sr and Zn sorption were analyzed, from single metal solutions and their equimolar mixture. Initial concentration of each metal in single metal solutions and total metal concentration in the mixture was 10-2 mol/dm3. Initial pH was adjusted to 5.0 ± 0.1. After 24 h equilibration of HAP samples with heavy metal solutions (solid/liquid ratio 1:200), the concentration of metals and of Ca2+ released from crystal lattice, as well as the final pH values were measured. The selectivity of all samples, regardless of the differences in their compositions, crystallinities, specific surface areas, points of zero charge and sorption capacities, was as follows: Pb > Cd > Zn > Sr. The same order was obtained for both single metal solutions and their mixture. In all cases, the sorption was followed by a decrease in final pH values, which are lower than the pHPZC values obtained by equilibration of HAP samples with an inert electrolyte (KNO3). A linear relationship between the amount of metals sorbed and Ca2+ released from HAP was observed. Also, a correlation between sorption capacities and physicochemical properties of HAP samples was found.
Authors: Xian Feng Li, Jin Bing Li, Jian She Chen, Zhi Xiang Zhang, Wu Jun Dai, Bao Lin Cui, Qiang Lin
Abstract: Ethylene oxide (EO) is an important organic chemical material, and Silver catalyst is an important petrochemical catalyst and is regarded as the core of EO/EG production process. The catalyst's performance is the major factor that directly determines the economic efficiency of commercial production of ethylene oxide. In this paper, we will introduce the development and application of YS silver catalysts developed by Beijing Research Institute of Chemical Industry, SINOPEC.
Authors: Cui Hua Liu, Chao Gao, De Yue Yan
Abstract: Amphiphilic hyperbranched polyamidoamine (PAMAM) and poly(sulfone-amine) (HPSA) were prepared and their dye-encapsulation properties were investigated. Both of them can carry water-soluble dyes from aqueous solution into chloroform. The selectivity of host to guests and the influence of interaction between different dyes on loading capacity were also investigated by performing comparable experiments. Encapsulation capacities are considered to have relationship with the water-solubility of the hyperbranched polymer core, the polarity difference between the hydrophilic core and the hydrophobic shell, the molecular structure of dyes, and the interactions between dyes.
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