Investigation of Low Molecular Weight Carbosilanes as Potential Single-Source Precursors to Silicon Carbide

1997 ◽  
Vol 495 ◽  
Author(s):  
M. A. Lienhard ◽  
L. V. Interrante ◽  
D. J. Larkin
Keyword(s):  
Molecular Weight ◽  
Growth Rate ◽  
Silicon Carbide ◽  
Low Molecular Weight ◽  
Single Source ◽  
Single Source Precursors ◽  
By Products ◽  
Sic Films

ABSTRACTSeveral volatile, low molecular weight, linear and cyclic carbosilanes containing a 1:1 Si:C ratio were studied as single-source CVD precursors to SiC. A comparison of methylsilane, 1,3-disilacyclobutane, 1,3-disila-n-butane, and 1,3,5-trisilacyclohexane in terms of both their pyrolysis chemistry (decomposition onset temperatures and gaseous by-products) and resulting film characterization (growth rate, stoichiometry, crystallinity and morphology) is presented. Polycrystalline β-SiC films were deposited by LPCVD on Si (100) substrates at temperatures ranging from 800°C to 1100°C by using each of these single-source precursors.

Low-temperature chemical vapour curing using iodine for fabrication of continuous silicon carbide fibres from low-molecular-weight polycarbosilane

2014 ◽  
Vol 2 (8) ◽  
pp. 2781 ◽  
Author(s):  
Junsung Hong ◽  
Kwang-Yeon Cho ◽  
Dong-Geun Shin ◽  
Jeong-Il Kim ◽  
Sung-Tag Oh ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Silicon Carbide ◽  
Low Temperature ◽  
Chemical Vapour ◽  
Low Molecular Weight

scholarly journals Removal of Trihalomethane Precursors by Nanofiltration in Low-SUVA Drinking Water

Water ◽  
2018 ◽  
Vol 10 (10) ◽  
pp. 1370 ◽  
Author(s):  
Yael Dubowski ◽  
Roni Greenberg-Eitan ◽  
Menachem Rebhun
Keyword(s):  
Molecular Weight ◽  
Organic Matter ◽  
Natural Organic Matter ◽  
Low Molecular Weight ◽  
Water Recovery ◽  
Formation Potential ◽  
Pressure Water ◽  
Membrane Type ◽  
Hydrophilic Organic Matter ◽  
By Products

Trihalomethanes (THMs) are prevalent disinfection by-products. High THM formation is usually associated with natural organic matter with high molecular weight and aromatic characteristics, which is efficiently removed by nanofiltration (NF). In the Sea of Galilee and the Israeli National Water Carrier (NWC), water shows high THM formation potential, although it mainly contains low molecular weight and hydrophilic organic matter with low aromaticity. In the present study, NF removal abilities were tested on treated NWC water using three different spiral wound membranes (NF90, NF270, and DL). Rejections and fluxes were tested as a function of pressure, water recovery, and membrane type. Feed and permeate dissolved organic carbon (DOC), UVA254, total THM formation (THMF), and total THM formation potential (THMFP), as well as alkalinity, conductivity, hardness, Ca2+, Mg2+, and Cl− were measured to evaluate rejection and THM formation reduction. The results demonstrated that NF can efficiently remove natural organic matter (NOM) and reduce THM formation, even in this challenging type of water. At low water recovery, membranes showed average rejection of about 70–85% for THMFP and THM. Upon elevating recovery, average THM and THMFP rejection decreased to 55–70%, with THM content still well below regulation limits. Of the membranes tested, the higher permeability of NF270 appears to make it economically favorable for the applications tested in this work.

Ceramic Coatings on Graphite via Polymer Vapor Pyrolysis Deposition Process

2008 ◽  
Vol 368-372 ◽  
pp. 1297-1299
Author(s):  
Xin Xing ◽  
Lin Liu ◽  
Xiao Zhong Huang ◽  
Xiao Dong Li
Keyword(s):  
Molecular Weight ◽  
Silicon Carbide ◽  
Pyrolysis Temperature ◽  
Deposition Process ◽  
Ceramic Coatings ◽  
Low Molecular Weight ◽  
Carbide Coatings ◽  
N2 Atmosphere ◽  
Amorphous Sic ◽  
Sic Coatings

Silicon carbide coatings on graphite were prepared through polymer vapor pyrolysis deposition process (PVPD) under N2 atmosphere. During this process, some low molecular weight substances that polycarbosilane (PCS) pyrolyzed can be deposited on graphite, and they can convert into SiC in high temperature. The results of XRD showed that amorphous SiC coatings were formed on graphite when the pyrolysis temperature was 1000°C, andβ-SiC phase formed in the coatings when the temperature up to 1250°C. Effects of the coatings on the microstructure and properties were investigated. It was shown that the uniform dense SiC coatings could be obtained by carefully controlling the pyrolysis temperature and ramping rate when the number molecular weight of PCS was in the range of 1,000~1,500.

SYNTHESIS AND CHARACTERIZATION OF FARNESENE-BASED POLYMERS

2017 ◽  
Vol 90 (2) ◽  
pp. 308-324 ◽  
Author(s):  
Taejun Yoo ◽  
Steven K. Henning
Keyword(s):  
Molecular Weight ◽  
Anionic Polymerization ◽  
Molar Mass ◽  
Functional Materials ◽  
Synthesis And Characterization ◽  
Low Molecular Weight ◽  
Structure Property ◽  
Structure Property Relationships ◽  
By Products

ABSTRACT A bio-based route to the production of trans-β-farnesene has recently been commercialized. Trans-β-farnesene is capable of being polymerized by both anionic and cationic pathways, creating low molecular weight polymers with structure–property relationships unique within the diene class of monomers. Trans-β-farnesene is produced through fermentation of sugar feedstocks. The pathway offers an alternative to petroleum-based feedstocks derived as by-products of naphtha or ethane cracking. Anionic polymerization of the monomer produces a highly branched “bottlebrush” structure, with rheological properties that are markedly different than those of linear diene polymers. Specifically, a lack of entanglements is observed even at relatively high molar masses. For hydroxyl-terminated oligomers, Tg as a function of molar mass follows a trend opposite non-functional materials. The synthesis and characterization of trans-β-farnesene–based polymers will be presented, including anionically prepared low molecular weight diols and monols.

scholarly journals Non-Extractable Polyphenols from Food By-Products: Current Knowledge on Recovery, Characterisation, and Potential Applications

Processes ◽  
2020 ◽  
Vol 8 (8) ◽  
pp. 925
Author(s):  
Yubin Ding ◽  
Ksenia Morozova ◽  
Matteo Scampicchio ◽  
Giovanna Ferrentino
Keyword(s):  
Molecular Weight ◽  
Current Knowledge ◽  
Biological Activities ◽  
Extraction Procedure ◽  
Economic Loss ◽  
Low Molecular Weight ◽  
Potential Applications ◽  
Valuable Compounds ◽  
Potential Food ◽  
By Products

Non-extractable polyphenols (NEPs), or bound polyphenols, are a significant fraction of polyphenols that are retained in the extraction residues after conventional aqueous organic solvent extraction. They include both high molecular weight polymeric polyphenols and low molecular weight phenolics attached to macromolecules. Current knowledge proved that these bioactive compounds possess high antioxidant, antidiabetic, and other biological activities. Plant-based food by-products, such as peels, pomace, and seeds, possess high amount of NEPs. The recovery of these valuable compounds is considered an effective way to recycle food by-products and mitigate pollution, bad manufacturing practice, and economic loss caused by the residues management. The current challenge to valorise NEPs from plant-based by-products is to increase the extraction efficiency with proper techniques, choose appropriate characterising methods, and explore potential functions to use in some products. Based on this scenario, the present review aims to summarise the extraction procedure and technologies applied to recover NEPs from plant-based by-products. Furthermore, it also describes the main techniques used for the characterisation of NEPs and outlines their potential food, pharmaceutical, nutraceutical, and cosmetic applications.

Mitigation mechanism of Cd-contaminated soils by different levels of exogenous low-molecular-weight organic acids and Phytolacca americana

RSC Advances ◽  
2015 ◽  
Vol 5 (56) ◽  
pp. 45502-45509 ◽  
Author(s):  
Huan Liu ◽  
Yun-guo Liu ◽  
Guang-ming Zeng ◽  
Jie-li Xie ◽  
Bo-hong Zheng ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Growth Rate ◽  
Organic Acids ◽  
Contaminated Soil ◽  
Contaminated Soils ◽  
Fast Growth ◽  
Low Molecular Weight ◽  
Phytolacca Americana ◽  
Different Levels ◽  
Fast Growth Rate

Phytolacca americana L. (pokeweed) is a promising plant for phytoremediation of cadmium (Cd)-contaminated soil, with its large biomass and fast growth rate.

scholarly journals Dynamic utilization of low-molecular-weight organic substrates across a microbial growth rate gradient

2021 ◽  
Author(s):  
K. Taylor Cyle ◽  
Annaleise R. Klein ◽  
Ludmilla Aristilde ◽  
Carmen Enid Martínez
Keyword(s):  
Molecular Weight ◽  
Growth Rate ◽  
Soil Solution ◽  
Oxidation State ◽  
Fungal Isolate ◽  
Chemical Characteristics ◽  
Low Molecular Weight ◽  
Bacterial Isolates ◽  
Ralstonia Pickettii ◽  
Use Efficiency

AbstractConstantly in flux, low-molecular-weight organic substances (LMWOSs) are at the nexus between microorganisms, plant roots, detritus, and the soil mineral matrix. Nominal oxidation state of carbon (NOSC) has been put forward as one way to parameterize microbial uptake rates of LMWOSs and efficiency of carbon incorporation into new biomass. In this study, we employed an ecophysiological approach to test these proposed relationships using targeted exometabolomics (1H-NMR, HR-LCMS) coupled with stable isotope (13C) probing. We assessed the role of compound class and oxidation state on uptake kinetics and substrate-specific carbon use efficiency (SUE) during the growth of three model soil microorganisms (Penicillium spinulosum, Paraburkholderia solitsugae, and Ralstonia pickettii) in media containing 34 common LMWOSs. Microbial isolates were chosen to span a gradient in growth rate (0.046-0.316 hr−1) and differ phylogenetically (a fungal isolate and two bacterial isolates). Clustered, co-utilization of LMWOSs occured for all three organisms, but temporal cluster separation was most apparent for P. solitsugae. Potential trends (p <0.05) for early utilization of more oxidized substrates were present for the two bacterial isolates (P. solitsugae and R. pickettii), but high variability (R2 > 0.15) and a small effect of NOSC indicate these are not useful relationships for prediction. The SUEs ranged from 0.16-0.99 and the hypothesized inverse relationship between NOSC and SUE was not observed. Thus, our results do not provide compelling support for NOSC as a predictive tool, implying that metabolic strategies of organisms may be more important than chemical identity in determining LMWOS cycling in soils.ImportanceCommunity-level observations from soils indicate that low-molecular-weight compounds of higher oxidation state tend to be depleted from soil solution faster and incorporated less efficiently into microbial biomass under oxic conditions. Here, we tested hypothetical relationships between substrate chemical characteristics and the order of substrate utilization by aerobic heterotrophs at the population-level in culture, using two bacterial isolates (Ralstonia pickettii and Paraburkholderia solitsugae) and one fungal isolate from soil (Penicillium spinulosum). We found weak relationships indicating earlier uptake of more oxidized substrates by the two bacterial isolates but no relationship for the fungal isolate. We found no relationship between substrate identity and substrate use efficiency. Our findings indicate that substrate chemical characteristics have limited utility for modeling the depletion of low-molecular-weight organics from soil solution and incorporation into biomass over broader phylogenetic gradients.

scholarly journals Effect of Oxidation on the Formation of Disinfectant By-products of Low Molecular Weight Organic Matter

2021 ◽  
Vol 20 (3) ◽  
Author(s):  
E. N. Hidayah ◽  
O. H. Cahyonugroho ◽  
M. Mirwan ◽  
R. B. Pachwarya ◽  
M. K. Asrori
Keyword(s):  
Molecular Weight ◽  
Organic Matter ◽  
Organic Compounds ◽  
Aromatic Compound ◽  
Aromatic Compounds ◽  
Sinapic Acid ◽  
Oxidation Potential ◽  
Low Molecular Weight ◽  
Safe Alternative ◽  
By Products

Some natural organic compounds (NOC) such as aromatic compounds can trigger the formation of disinfection by-products (DBPs). In chlorination (disinfectant) process resultant water quality depletes. Some safe alternative oxidants are needed for cleaning water pollutants. KMnO4 had shown better oxidation results, especially for reducing aromatic and non-aromatic organic compounds present in water. The aim of this study was to analyze the effect of KMnO4 and Ca(OCl)2 oxidants on the concentration of high and low molecular weight organic matter including aromatic compounds in the water sample. In this experiment, artificial organic compounds, namely sinapic acid (high molecular weight aromatic compound) and resorcinol (low molecular weight aromatic compound) were used to identify the characteristic of organic matter under different molecular weights. Sinapic acid and resorcinol were oxidized by using KMnO4 and Ca(OCl)2 with a minimum contact time of 60 minutes. Samples were analyzed for aromatic contents and total organic carbon (TOC) before and after completion of the experiment by using UV-Vis spectrophotometer at 254 nm wavelength (UV254). It has been observed that both oxidants increased TOC concentration. Ca(OCl)2 produces a higher percentage of organic matter degradation by-products (DBPs) such as chloroform (CHCl3) a highly toxic compound than KMnO4. Since Ca(OCl)2 has a higher oxidation potential than KMnO4. It has been observed that KMnO4 is a safer oxidant than Ca(OCl)2 as potassium permanganate produces less amount of DBPs.

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