scholarly journals Correlation Between Saturated Fatty Acid Chain-Length and Intermolecular Forces Determined with Terahertz Spectroscopy

2019 ◽  
Author(s):  
Shuting Fan ◽  
Michael Ruggiero ◽  
Zhengfang Qian ◽  
Vincent P. Wallace

<p>We measured crystalline (C-form) saturated fatty acids with even carbon numbers ranging from 12 to 20 using temperature dependent terahertz time-domain spectroscopy (THz-TDS). Absorption features between 0.5 to 2.75 THz were identified at temperatures from 96 K to 293 K, and a systematic red-shift was obvserved with the increasing carbon chain length. The origins of these absorption bands were uncovered using state-of-the-art <i>ab initio</i> density functional theory (DFT) calculations. Similar vibrational motions in the absorption bands of the different materials highlight the unique role that THz-TDS has for probing weak non-covalent interactions in these materials. Our results showcase the utility of the terahertz region, which is beyond the scope of related vibrational techniques, providing direct evidence of the effect of chain length on the intermolecular interactions of these molecules. </p>

2019 ◽  
Author(s):  
Shuting Fan ◽  
Michael Ruggiero ◽  
Zhengfang Qian ◽  
Vincent P. Wallace

<p>We measured crystalline (C-form) saturated fatty acids with even carbon numbers ranging from 12 to 20 using temperature dependent terahertz time-domain spectroscopy (THz-TDS). Absorption features between 0.5 to 2.75 THz were identified at temperatures from 96 K to 293 K, and a systematic red-shift was obvserved with the increasing carbon chain length. The origins of these absorption bands were uncovered using state-of-the-art <i>ab initio</i> density functional theory (DFT) calculations. Similar vibrational motions in the absorption bands of the different materials highlight the unique role that THz-TDS has for probing weak non-covalent interactions in these materials. Our results showcase the utility of the terahertz region, which is beyond the scope of related vibrational techniques, providing direct evidence of the effect of chain length on the intermolecular interactions of these molecules. </p>


2019 ◽  
Vol 55 (25) ◽  
pp. 3670-3673 ◽  
Author(s):  
Shuting Fan ◽  
Michael T. Ruggiero ◽  
Zihui Song ◽  
Zhengfang Qian ◽  
Vincent P. Wallace

Chain-length dependent intermolecular interactions of saturated fatty acids are directly probed with THz-TDS and confirmed by ab initio calculations.


Minerals ◽  
2020 ◽  
Vol 10 (4) ◽  
pp. 378 ◽  
Author(s):  
Jun Qiu ◽  
Dongliang Liu ◽  
Yueting Wang ◽  
Guowei Chen ◽  
Shan Jiang ◽  
...  

In this work, the effect of layer charge density of Na-montmorillonite (Na-MT) and carbon chain length of alkyl ammonium on the structure and gel property of organo-montmorillonite (organo-MT) was studied by using X-ray diffraction (XRD), Fourier transform infrared (FTIR), thermogravimetric (TG) analysis, contact angle test, molecular dynamics (MD) simulation, and gel apparent viscosity determination experiment. The results of XRD show that Na-MT with lower layer charge density is easier to swell after intercalation of alkyl ammonium, and the basal spacing of organo-MT increases with the increase of carbon chain length. The results of FTIR show that the absorption bands at 2924 cm−1 and 2853 cm−1 shift towards low frequency region with the increase of carbon chain length, and the absorption bands at 515 cm−1 and 463 cm−1 move towards high frequency region when the layer charge density increases. The mass loss of organo-MT evidently increases with the increase of layer charge density of Na-MT or carbon chain length of alkyl ammonium. The contact angle test results are well in line with the TG data and reveal that alkyl ammonium with longer carbon chain can significantly improve the hydrophobicity of organo-MT. MD simulation indicates that, when the layer charge density is low, the distribution of alkyl ammonium gradually changes from parallel double layers to partially inclined distribution with the increase of carbon chain length, but when the layer charge density is high, the distribution of alkyl ammonium gradually changes from three layers into four layers. The test results of the apparent viscosity of the gel formed by organo-MT in xylene show that the apparent viscosity of organo-MT gel is negatively correlated with the layer charge density of Na-MT and positively correlated with the carbon chain length of alkyl ammonium.


Circulation ◽  
2016 ◽  
Vol 133 (suppl_1) ◽  
Author(s):  
Jaike Praagman ◽  
Ester A de Jonge ◽  
Jessica C Kiefte de Jong ◽  
Joline W Beulens ◽  
Ivonne Sluijs ◽  
...  

Introduction: The association between dietary saturated fatty acids (SFA) and the risk of coronary heart disease (CHD) is heavily debated and appears to be more complex than initially thought. The food source and carbon chain length of SFA, as well as the macronutrient replacing SFA in the diet may affect the association between dietary SFA and CHD. Hypothesis: We assessed the hypothesis that the association between dietary SFA and incident CHD is dependent on the food source of SFA, the carbon chain length of SFA, and the substituting macronutrient. Methods: From the Rotterdam Study, we included 4,722 healthy men and women, aged 55 years or older. Baseline (1998-1993) SFA intake was assessed using a validated food frequency questionnaire. Incident CHD comprised fatal and non-fatal myocardial infarctions and coronary mortality up to January 2011, and was assessed through digital linkage with municipality records and general practitioners. We used multivariable Cox’ proportional hazard models to calculate CHD risks for higher intakes of total SFA, SFA from specific food sources, SFA differing in carbon chain length, and for higher intakes of other macronutrients at the expense of total SFA. Results: During a median follow up of 16.3 years 569 CHD events occurred. Median total SFA intake was 15.7 en% per day, and the top three food sources were cheese (20.0%), meat (17.8%), and milk and milk products (13.1%). Total SFA intake was not significantly associated with CHD risk (Hazard Ratio (HR) per 5 en%: 1.13, 95%CI: 0.94, 1.22). Neither was SFA from specific food sources, although the data suggested an increased CHD risk for a higher intake of SFA from meat (HR per 1 en%: 1.06, 95%CI: 0.99, 1.14). Regarding SFA differing in carbon chain lengths, a higher CHD risk was observed for C16:0 intake (HR 1en% : 1.18, 95%CI: 1.03, 1.35), but not for the remaining SFA. No significant associations with CHD risk were observed for each 5% lower intake of energy from SFA and a concomitant higher intake of 5% of energy from carbohydrates (HR 5en% : 0.90: 0.80, 1.02), polyunsaturated fatty acids (HR 5en% : 0.90, 95%CI: 0.71, 1.15), cis -monounsaturated fatty acids (HR 5en% :1.09, 95%CI: 0.98, 1.22), or vegetable protein (HR 5en% : 0.88, 95%CI: 0.50, 1.53).The exception was substitution of SFA with animal protein, which was associated with higher CHD risk (HR 5en% : 1.24, 95%CI: 1.01, 1.51). Conclusions: In this Dutch elderly population, with a high median intake of total SFA, the association between SFA intake and CHD risk depends on the SFA food source and carbon chain length. Future intervention studies are needed to determine the importance of the SFA food sources, and to confirm that C16:0 is more strongly related with CHD risk than other SFA.


2021 ◽  
pp. 117119
Author(s):  
Mansoor Ul Hassan Shah ◽  
Ambavaram Vijaya Bhaskar Reddy ◽  
Suzana Yusup ◽  
Masahiro Goto ◽  
Muhammad Moniruzzaman

2021 ◽  
Author(s):  
Liwen Zeng ◽  
Kong-qiu Hu ◽  
Zhi-wei Huang ◽  
Lei Mei ◽  
Xianghe Kong ◽  
...  

Herein, we report a new uranyl-organic polyhedron U4L4 (L=BTPCA) assembled from uranyl and a semirigid tritopic ligand. By adjusting the carbon chain length of the organic templates, two complexes can...


2014 ◽  
Vol 82 ◽  
pp. 172-180 ◽  
Author(s):  
En-Jun Gao ◽  
Hong Fu ◽  
Ming-Chang Zhu ◽  
Chi Ma ◽  
Shi-Kai Liang ◽  
...  

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