Ordering Phenomena in Surfactant Systems: From Micellar Solutions to Gel and Crystalline Phases

2015 ◽  
Vol 229 (10-12) ◽  
Author(s):  
Holger Gibhardt ◽  
Chandrashekara R. Haramagatti ◽  
Ahmed Kh. Islamov ◽  
Oleksandr I. Ivankov ◽  
Alexander I. Kuklin ◽  
...  
Keyword(s):  
Small Angle Neutron Scattering ◽  
Micellar Solution ◽  
Alkyl Chain ◽  
Micellar Solutions ◽  
Model Substances ◽  
Gel Phase ◽  
Surfactant Systems ◽  
High Concentrations ◽  
Chain Lengths ◽  
Long Chain

AbstractThe phase behavior of surfactant systems is investigated using alkyltrimethylammonium bromide surfactants with different alkyl chain lengths (dodecyl-, tetradecyl-, hexadecyl- and octadecyl) as model substances. The transitions between micellar solution, gel-phase and crystalline phase are characterized by the combination of Raman spectroscopy and small angle neutron scattering. It is demonstrated that in systems with small surfactant molecules the aqueous solution crystallizes directly on cooling to form hydrated crystals while an intermediate gel phase is observed in long chain systems. The cross-over is found for the hexadecyl-compound where the gel phase appears only at high concentrations.

scholarly journals EFFECT OF LONG-CHAIN ALKYLAMINE ON THE DISPERSIBILITY AND TRIBOLOGICAL PROPERTIES OF ALKYL-GRAPHENE IN LUBRICANT OIL

2018 ◽  
Vol 56 (2A) ◽  
pp. 163-173 ◽  
Author(s):  
Nguyen Huu Van
Keyword(s):  
Electron Microscopy ◽  
Alkyl Chain ◽  
X Ray Diffraction ◽  
X Ray ◽  
Lubricant Oil ◽  
Transmission Electron ◽  
Lubrication Oil ◽  
Carboxylic Groups ◽  
Chain Lengths ◽  
Long Chain

We report on the preparation of Alkyl-Graphene by hydrothermal method, and their dispersion in lubrication oil. The alkylated graphenes with variable alkyl chain lengths (Cn = 8, 12, 18) are prepared by coupling of alkylamine with carboxylic groups of graphene oxide (GO). FTIR, XPS, TGA methods were used to analyze and assess the GO modified ability by amine. The morphology and microstructure of prepared GO and alkyl-graphene were examined using field emission scanning electron microscopy (FESEM), transmission electron microscopy (HRTEM), X-ray diffraction (XRD). The experiments confirmed the formation of GO and alkyl-graphene. Stably distributed system of alkyl-graphene in SN500 reached 13.2 g/l with octylamine and 9.5 g/l with decylamine and 6.0 g/l with dodecylamine. The lubricating characteristics of lubrication oil containing alkyl-graphene was determined according to ASTM D2783. Evaluation of the reduction performance of SN500 oil when adding with alkyl-graphene: modified GO by octylamine gave the best performance compared to decylamine, dodecylamine. The reduction of abrasion reached 11.3 % at 0.3 g/l and 12.5% at 0.4 g/l of octyl-graphene.

Chemical and Apoptotic Properties of Hydroxy-Ceramides Containing Long-Chain Bases with Unusual Alkyl Chain Lengths

2008 ◽  
Vol 144 (1) ◽  
pp. 95-106 ◽  
Author(s):  
Mamoru Kyogashima ◽  
Keiko Tadano-Aritomi ◽  
Toshifumi Aoyama ◽  
Akiko Yusa ◽  
Yoshiko Goto ◽  
...  
Keyword(s):  
Alkyl Chain ◽  
Chain Lengths ◽  
Long Chain

scholarly journals Facile construction of a family of supramolecular gels with good levofloxacin hydrochloride loading capacity

RSC Advances ◽  
2021 ◽  
Vol 11 (21) ◽  
pp. 12641-12648
Author(s):  
Renyuan Chen ◽  
Caidie Xu ◽  
Yihao Lei ◽  
Hongxin Liu ◽  
Yabin Zhu ◽  
...  
Keyword(s):  
Molecular Weight ◽  
Alkyl Chain ◽  
Low Molecular Weight ◽  
Loading Capacity ◽  
Supramolecular Gels ◽  
Low Molecular Weight Gelators ◽  
Chain Lengths

A family of low molecular weight gelators with different alkyl chain lengths was constructed, having excellent gelation ability and antibiotic loading capacity. A low molecular weight hydrogelator was obtained by adjusting the length of alkyl chain.

The Use of N-alkanes for Estimating Intake and Passage Rate in Horses

1996 ◽  
Vol 1996 ◽  
pp. 98-98
Author(s):  
B M L McLean ◽  
R W Mayes ◽  
F D DeB Hovell
Keyword(s):  
Recent Work ◽  
Chain Length ◽  
Carbon Chain ◽  
Carbon Chain Length ◽  
Passage Rate ◽  
Forage Crops ◽  
Carbon Chains ◽  
Naturally Occurring ◽  
Chain Lengths ◽  
Long Chain

Alkanes occur naturally in all plants, although forage crops tend to have higher alkane contents than cereals. N-alkanes have odd-numbered carbon chains. They are ideal for use as markers in feed trials, because, they are inert, indigestible and naturally occurring, and can be recovered in animal faeces. Synthetic alkanes (even-numbered carbon chains) are available commercially and can also used as external markers. Dove and Mayes (1991) cite evidence indicating that faecal recovery of alkanes in ruminants increases with increasing carbon-chain length. Thus the alkane “pairs” (e.g. C35 & C36, and C32 & C33) are used in calculating intake and digestibility because they are long chain and adjacent to each other. However, recent work by Cuddeford and Mayes (unpublished) has found that in horses the faecal recovery rates are similar regardless of chain lengths.

Circulating Ceramides and Sphingomyelins and Risk of Mortality: The Cardiovascular Health Study

2021 ◽  
Author(s):  
Amanda M Fretts ◽  
Paul N Jensen ◽  
Andrew N Hoofnagle ◽  
Barbara McKnight ◽  
Colleen M Sitlani ◽  
...  
Keyword(s):  
Fatty Acids ◽  
Fatty Acid ◽  
Cardiovascular Health ◽  
Health Study ◽  
Cardiovascular Health Study ◽  
Risk Of Death ◽  
Risk Of Mortality ◽  
Increased Risk ◽  
High Concentrations ◽  
Long Chain

Abstract Background Recent studies suggest that associations of ceramides (Cer) and sphingomyelins (SM) with health outcomes differ according to the fatty acid acylated to the sphingoid backbone. The purpose of this study was to assess associations of Cer and SM species with mortality. Methods The study population included participants from the Cardiovascular Health Study (CHS), a community-based cohort of adults aged ≥65 years who were followed from 1992–2015 (n = 4612). Associations of plasma Cer and SM species carrying long-chain (i.e., 16:0) and very-long-chain (i.e., 20:0, 22:0, 24:0) saturated fatty acids with mortality were assessed using Cox proportional hazards models. Results During a median follow-up of 10.2 years, 4099 deaths occurred. High concentrations of Cer and SM carrying fatty acid 16:0 were each associated with an increased risk of mortality. Conversely, high concentrations of several ceramide and sphingomyelin species carrying longer fatty acids were each associated with a decreased risk of mortality. The hazard ratios for total mortality per 2-fold difference in each Cer and SM species were: 1.89 (95% CI), 1.65–2.17 for Cer-16, 0.79 (95% CI, 0.70–0.88) for Cer-22, 0.74 (95% CI, 0.65–0.84) for Cer-24, 2.51 (95% CI, 2.01–3.14) for SM-16, 0.68 (95% CI, 0.58–0.79) for SM-20, 0.57 (95% CI, 0.49–0.67) for SM-22, and 0.66 (0.57–0.75) for SM-24. We found no association of Cer-20 with risk of death. Conclusions Associations of Cer and SM with the risk of death differ according to the length of their acylated saturated fatty acid. Future studies are needed to explore mechanisms underlying these relationships.

Antibacterial Effects of Long-Chain Polyphosphates on Selected Spoilage and Pathogenic Bacteria

2008 ◽  
Vol 71 (7) ◽  
pp. 1401-1405 ◽  
Author(s):  
JEREMY A. OBRITSCH ◽  
DOJIN RYU ◽  
LUCINA E. LAMPILA ◽  
LLOYD B. BULLERMAN
Keyword(s):  
Food Industry ◽  
Pathogenic Bacteria ◽  
Antimicrobial Activities ◽  
Lag Phase ◽  
E Coli ◽  
Inhibition Of Growth ◽  
K 12 ◽  
Chain Lengths ◽  
And Staphylococcus Aureus ◽  
Long Chain

The antimicrobial activities of four long-chain food-grade polyphosphates were studied at concentrations allowed in the food industry (<5,000 ppm) in defined basal media by determining the inhibition of growth of three gram-negative and four gram-positive spoilage and pathogenic bacteria. Both generation time and lag phase of Escherichia coli K-12, E. coli O157: H7, and Salmonella Typhimurium were increased with all of the polyphosphates tested. Bacillus subtilis and Staphylococcus aureus were more sensitive to polyphosphates, but not in all cases, with multiphased growth. The growth of Lactobacillus plantarum was inhibited by polyphosphates at concentrations above 750 ppm, but the lag time of Listeria monocytogenes was shortened by the presence of polyphosphates. No single polyphosphate was maximally inhibitory against all bacteria. Polyphosphates with chain lengths of 12 to 15 were significantly different from those with chain lengths of 18 to 21 depending on the organism and concentrations of polyphosphate used. Overall, higher polyphosphate concentrations resulted in greater inhibition of bacterial growth.

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