Saturated Carbon Chains Research Articles

Tandem, Catalyst‐Free C‐C Synthesis of Nitriles from Aldehydes and Methyl Cyanoacetate with Sodium Hypophosphite

Saturated carbon chain elongation is a common refrain in numerous synthetic pathways. While the formation of C‐C single bonds is of primary importance in organic synthesis, simultaneous introduction of functional groups such as nitrile or ester can reasonably increase its practical utility to prepare multifunctional products. Knoevenagel reaction is one of the powerful tools to create carbon backbones of organic molecules; however, it requires subsequent reduction and/or decarboxylation to achieve a product with a saturated carbon chain. Herein we report a convenient one‐step protocol for the reductive condensation between methyl cyanoacetate and aldehydes in the presence of stable, ecologically benign, cheap and available in bulk amounts sodium hypophosphite as a reductant. A description of both the reaction capabilities and limitations is given in this paper.

Captivating Combustion Traits of Bio-Oil Droplets Enriched with Bio-Additives from the Areca Shell Waste

Fuel derived from crude vegetable oil, such as coconut oil, holds promise as an alternative energy source to mitigate the increasing reliance on fossil fuels driven by population growth and industrial activities. The experiment involved suspending a single droplet of crude coconut oil mixed with activated carbon from areca shell waste and placed at the junction on R-type thermocouple (Pt/Pt-Rh13%). The droplets were ignited using a hot wire and subjected to atmospheric pressure and room temperature. Coconut oil comprises a saturated triglyceride carbon chain compound of approximately 91%, and areca shell waste possesses a porous structure that fosters favorable interactions between fuel molecules. The droplet combustion method was selected to streamline the process and enhance the contact area between air and fuel, thereby boosting the reactivity of fuel molecules. The research found that adding activated carbon shortens the carbon chain, making it more reactive and easier for the fuel to ignite. Specifically, activated carbon significantly enhances fuel performance at a concentration of two parts per million (ppm). At this level, the fuel absorbs heat more effectively and ignites faster compared to one ppm and three ppm levels. Moreover, the results show that heat absorption occurs slowly at one ppm, while at three ppm, the increased molecular mass of the fuel can strengthen carbon-bonding forces. These factors contribute to a longer ignition time for the fuel. The findings suggest that the activated carbon from areca shell waste can play a good role as a combustion catalyst, where overall, fuel performance increases.

Phospholipid biosynthesis regulation for improving pigment production by Monascus in response to ammonium chloride stress.

In the actual industrial production process, the efficient biosynthesis and secretion of Monascus pigments (MPs) tend to take place under abiotic stresses, which often result in an imbalance of cell homeostasis. The present study aimed to thoroughly describe the changes in lipid profiles in Monascus purpureus by absolute quantitative lipidomics and tandem mass tag-based quantitative proteomics. The results showed that ammonium chloride stress (15 g/L) increased MP production while inhibiting ergosterol biosynthesis, leading to an imbalance in membrane lipid homeostasis in Monascus. In response to the imbalance of lipid homeostasis, the regulation mechanism of phospholipids in Monascus was implemented, including the inhibition of lysophospholipids production, maintenance of the ratio of PC/PE, and improvement of the biosynthesis of phosphatidylglycerol, phosphatidylserine, and cardiolipin with high saturated and long carbon chain fatty acids through the CDP-DG pathway rather than the Kennedy pathway. The inhibition of lysophospholipid biosynthesis was attributed to the upregulated expression of protein and its gene related to lysophospholipase NTE1, while maintenance of the PC/PE ratio was achieved by the upregulated expression of protein and its gene related to CTP: phosphoethanolamine cytidylyltransferase and phosphatidylethanolamine N-methyltransferase in the Kennedy pathway. These findings provide insights into the regulation mechanism of MP biosynthesis from new perspectives.IMPORTANCEMonascus is important in food microbiology as it produces natural colorants known as Monascus pigments (MPs). The industrial production of MPs has been achieved by liquid fermentation, in which the nitrogen source (especially ammonium chloride) is a key nutritional parameter. Previous studies have investigated the regulatory mechanisms of substance and energy metabolism, as well as the cross-protective mechanisms in Monascus in response to ammonium chloride stress. Our research in this work demonstrated that ammonium chloride stress also caused an imbalance of membrane lipid homeostasis in Monascus due to the inhibition of ergosterol biosynthesis. We found that the regulation mechanism of phospholipids in Monascus was implemented, including inhibition of lysophospholipids production, maintenance of the ratio of PC/PE, and improvement of biosynthesis of phosphatidylglycerol, phosphatidylserine, and cardiolipin with high saturated and long carbon chain fatty acids through the CDP-DG pathway. These findings further refine the regulatory mechanisms of MP production and secretion.

Effective Coupling Model to Treat the Odd-Even Effect on the Current-Voltage Response of Saturated Linear Carbon Chains Single-Molecule Junctions.

The calculation of the electrical charge transport properties of alkanes C n H 2n S 2 with (n = 4-11) was performed to understand the odd-even effect on its current-voltage response. The extended molecule and broadband limit models were used to describe the molecular junction and covalent coupling with the electrodes. It was shown that among the participating molecular orbitals, HOMO and HOMO-1 are the ones with the most charge transport contribution. Moreover, the odd-even effect is caused by the alternation of the eigenvalues of some frontier orbitals as a function of the number of carbons, especially the HOMO that dominates the electrical transport. It could also be noted that when the current is analyzed outside the resonance, the relationship with the number of carbons exponentially decays, confirming the reports in the literature. To the best of our knowledge, a first principle study of the odd-even effect in symmetric systems composed by linear saturated carbon chains covalently coupled to electrodes has not been reported yet.

Effect of Fatty Acid Unsaturation on the Intermolecular Weak Interaction at the Low-Rank Coal-Water Interface: Density Functional Theory Calculations and Experimental Study.

The study on the effect of fatty acid saturation on low-rank coal (LRC) flotation is still limited. In this investigation, density functional theory (DFT) combined with Zeta potential and Fourier transform infrared spectroscopy (FTIR) was used to study the mechanism of intermolecular weak interaction at the LRC-water interface of fatty acids (decanoic acid (DA), undecylenic acid (UA), and phenyl propionic acid (PA)) with different saturations and different dodecane (D) composition hydrocarbon oil-fatty acid mixed collectors (D-DA, D-UA, D-PA). The findings demonstrated that the hydrogen bond interaction and electrostatic interaction between the UA/PA with unsaturated bonded carbon chains and the LRC molecular fragments/water molecules were stronger than DA without a saturated bond carbon chain, and UA/PA strengthened its interaction with water molecules on the whole, even PA molecules would preferentially interact with water molecules. The unsaturated bond had a minimal impact on the adsorption of the LRC hydrophobic site, and the strength of the hydrogen bond between the mixed collector and LRC is D-DA > D-UA > D-PA. In the actual flotation process, the strong hydrogen bonding and electrostatic interaction between UA/PA and water molecules weaken the collection performance of the mixed collector D-UA/D-PA for LRC, which also confirmed the research results of DFT, FTIR, and Zeta.

Fractioning and Compared 1H NMR and GC-MS Analyses of Lanolin Acid Components.

The management of food and food-related wastes represents a growing global issue, as they are hard to recycle and dispose of. Foremost, waste can serve as an important source of biomasses. Particularly, fat-enriched biomasses are receiving more and more attention for their role in the manufacturing of biofuels. Nonetheless, many biomasses have been set aside over the years. Wool wax, also known as lanolin, has a huge potential for becoming a source of typical and atypical fatty acids. The main aim of this work was to evaluate and assess a protocol for the fractioning of fatty acids from lanolin, a natural by-product of the shearing of sheep, alongside the design of a new and rapid quantitative GC-MS method for the derivatization of free fatty acids in fat mixtures, using MethElute™. As the acid portion of lanolin is characterized by the presence of both aliphatic and hydroxylated fatty acids, we also evaluated a procedure for the parting of these two species, by using NMR spectroscopy, benefitting of the different solubilities of the components in organic solvents. At last, we evaluated and quantified the fatty acids and the α-hydroxy fatty acids present in each attained portion, employing both analytical and synthetic standards. The performed analyses, both qualitative and quantitative, showed a good performance in the parting of the different acid components, and GC-MS allowed to speculate that the majority of α-hydroxylated fatty acids is formed of linear saturated carbon chains, while the totality of properly said fatty acids has a much more complex profile.

A Novel Drug Self-Delivery System from Fatty Alcohol Esters of Tranexamic Acid for Venous Malformation Sclerotherapy.

Venous malformation (VM), which causes severe damage to patients’ appearance and organ function, is one of the most common vascular malformations. At present, many drugs in clinical treatment cause various adverse reactions. Herein, we synthesized cationic amphiphilic gelators (TA6, TA8, and TA9) by introducing saturated carbon chains of different lengths to tranexamic acid (TA), which could self-assemble into low-molecular-weight gels (LMWGs) as drug delivery carriers by hydrogen bonds, van der Waals forces, and hydrophobic interactions. The rheological properties, gelation driving force and drug release profiles of TA6, TA8, and TA9 hydrogels were characterized, and the results indicated that the hydrogels prepared in this study possessed the typical characteristics of a gel and could release drugs slowly. More importantly, the TA9 gelator showed significant pharmacological activity, in that it served as both an active drug compound and a drug carrier. The in vitro experiments demonstrated that TA9 induced HUVECs death and hemolysis by destroying cell membranes in a dose-dependent manner, and caused cell death and hemolysis at a concentration of 0.09 µM/mL. Meanwhile, we found TA9 could interact not only with fibrinogen, but also with other endogenous molecules in the blood. After the administration of TA9 hydrogel for 15 days, macroscopic imaging and histological evaluation in mice and rabbits displayed obvious thrombi, inflammatory reactions, and venous embolization, indicating that the mechanism of the TA9 hydrogel in treating VM was involved in two processes. Firstly, the TA9 hydrogel relied on its mechanical strength to physically block veins and continuously release TA9, in situ, for targeted therapy. Then, TA9 destroyed endothelial cells and damaged venous walls critically, causing thrombi. Most excitingly, TA9 was hydrolyzed to TA by enzymes that inhibited the degradation of thrombi by plasmin to prolong the embolization time and to promote venous fibrosis. Compared with other clinically available sclerosants, the degradation of TA9 also empowered a better biocompatibility and biodegradability for the TA9 hydrogel. In conclusion, we synthesized a potentially safe and effective derivative of TA and developed a low-molecular-weight gel as a self-delivery system for TA in treating VM.

Structural characterization and confined pyrolysis of resistant aliphatic biopolymer derived from cyanobacteria

Two cultured cyanobacteria species were divided into three fractions, investigated using Rock-Eval, elemental analysis, and 13C cross polarization/total sideband suppression (CP/TOSS) nuclear magnetic resonance (NMR) to obtain information on the structure, composition, and oil and gas production potential (OGP) of these species. Confined pyrolysis experiments were performed on isolated acid nonhydrolyzable organic matter (NHOM) fractions. The results showed that the NHOM fractions from Oscillatoria sp. (OSC_NHOM) and Calothrix anomala (CAL_NHOM) were similar to the highly aliphatic algaenan in structure and capable of generating gas and oil. Pyrolysis experiments of the OSC_NHOM and CAL_NHOM fractions demonstrated that they contained a saturated and unbranched carbon chain with up to 33 carbon atoms and had high OGP. The maximum oil yield (59% for OSC_NHOM and 47% for CAL_NHOM) derived from the pyrolysis experiments was higher than that from oil-prone carbon (46% for OSC_NHOM and 39% for CAL_NHOM), suggesting that the 13C CP/TOSS NMR method slightly underestimates the oil production potential of cultured cyanobacterial (and possibly algal) biopolymers. Our investigation confirms the presence of algaenan-like biopolymers in a broader suite of cyanobacteria.

Artificial Neural Network Modeling of Glass Transition Temperatures for Some Homopolymers with Saturated Carbon Chain Backbone.

The glass transition temperature (Tg) is an important decision parameter when synthesizing polymeric compounds or when selecting their applicability domain. In this work, the glass transition temperature of more than 100 homopolymers with saturated backbones was predicted using a neuro-evolutive technique combining Artificial Neural Networks with a modified Bacterial Foraging Optimization Algorithm. In most cases, the selected polymers have a vinyl-type backbone substituted with various groups. A few samples with an oxygen atom in a linear non-vinyl hydrocarbon main chain were also considered. Eight structural, thermophysical, and entanglement properties estimated by the quantitative structure–property relationship (QSPR) method, along with other molecular descriptors reflecting polymer composition, were considered as input data for Artificial Neural Networks. The Tg’s neural model has a 7.30% average absolute error for the training data and 12.89% for the testing one. From the sensitivity analysis, it was found that cohesive energy, from all independent parameters, has the highest influence on the modeled output.

Tuning the lipophilic nature of pyclen-based 90Y3+ radiopharmaceuticals for β-radiotherapy

Abstract Pyclen-dipicolinate chelates proved to be very efficient chelators for the radiolabeling with β–-emitters such as 90Y. In this study, a pyclen-dipicolinate ligand functionalized with additional C12 alkyl chains was synthesized. The radiolabeling with 90Y proved that the addition of saturated carbon chains does not affect the efficiency of the radiolabeling, whereas a notable increase in lipophilicity of the resulting 90Y radiocomplex was observed. As a result, the compound could be extracted in Lipiodol® and encapsulated in biodegrable pegylated poly(malic acid) nanoparticles demonstrating the potential of lipophilic pyclen-dipicolinate derivatives as platforms for the design of radiopharmaceuticals for the treatment of liver or brain cancers by internal radiotherapy.

Fundamental bioflotation aspects of hematite using an extracted Rhodococcus opacus by-product

The aim of this study is to assess the floatability of hematite using a crude biosurfactant (BS) extracted from Rhodococcus opacus. Throughout high-pressure ethanol extraction, unrefined surfactant was extracted from the bacteria with a yield of 0.3 g/L. An FTIR analysis on this extract, shows the presence of alcohol (–OH) and ketone (C=O) groups, as well as saturated and unsaturated carbon chains, which might originate from mycolates and trehalolipids moieties reported in literature. In addition, FTIR analysis on the modified mineral surface with the unrefined surfactant, confirms a strong interaction between hematite and the crude biosurfactant, showing similar vibrational peaks regarding the hydroxyl and carboxylate groups at 1631 and 3436 cm-1, respectively. Biosurfactant interaction with the mineral particles shifted the isoelectric point from 7.5 to 3.2, turning the hematite more hydrophobic in acidic environments. Surface tension measurements indicate that the unrefined surfactant is slightly more effective, decreasing the surface tension of water compared to the bacteria itself, with a variation of 4 mM/m. Finally, throughout microflotation tests in a Hallimond tube, it is shown that the surfactant doubles bacteria recovery efficiency, reaching a maximum recovery of around 95 % in acidic conditions, which is consistent with electrophoretic studies. The statistical models adjust well the experimental data, achieving R2 values of 93.6 and 91.1% for the hematite flotation using the biomass and the biosurfactant, respectively.

ANALISA UNSUR HARA MIKRO DARI FLY ASH LIMBAH INDUSTRI PULP DAN KERTAS

The pulp and paper industry continues to grow and produces large amounts of fly ash waste from the biomass combustion process. Alternative waste management besides landfills needs to be developed so that the use of fly ash can be ecologically and economically acceptable, such as for land applications in industrial plantations, especially on peat soils. This paper presents the results of the analysis of micro nutrients from fly ash from pulp and paper mill waste that can be used for agriculture and forestry. The elemental content of boron (B) and zinc (Zn) can be detected in fly ash samples both by lauryl amine extraction and stearyl amine extraction, where the optimum amount is obtained using 15 gram of fatty amine and n-hexane solvent with a processing time of 4 hours. Stearyl amine gives a higher yield than lauryl amine because it has a longer saturated carbon chain.

Are all-atom any better than united-atom force fields for the description of liquid properties of alkanes?

Alkanes are a fundamental part in empirical force fields (FF) not only due to their technological relevance, but also due to the prevalence of alkane moieties in organic molecules, e.g., compounds containing a saturated carbon chain. Therefore, a good description of alkane interactions is crucial for determining the quality of a FF. In this study, the performance of 12 empirical force fields (FF) was evaluated in the context of reproducing liquid properties of alkanes. More specifically, n-octane was chosen as a reference compound since it is a liquid in a broad temperature range and it has numerous experimental data for thermodynamic, transport, and structural properties, as well as for their temperature dependencies. A normalized root-mean-square deviation (NRMSD) analysis was used to rank the force fields in their ability to reproduce the experimental data. Five out of the six best force fields considered were united-atom models. The GROMOS force field showed the smallest deviation in terms of NRMSD, followed by TRAPPE-EH, NERD, CHARMM-UA, TRAPPE-UA, and OPLS-UA. This overall better performance of the united-atom force fields indicates that complexity does not always bring quality.

Electron scattering processes in steroid molecules via NEGF-DFT: The opening of conduction channels by central oxygen

We present a careful analysis of the electron transport in a variety of steroid derivatives attached among Au (111) electrodes. Our discussion is based on the non-equilibrium Green’s function formalism coupled to the density functional theory, as well as appropriate parameters, such as the current-voltage behavior, differential conductance, rectification ratio, transmittance, the projected density of states, and the corresponding eigenchannels. The systems investigated present antagonistic features. While the cholesterol has no appreciable electrical rectification and works as an insulator, cortisol presents an evident diode-like behavior with an intense micro-ampere current with a strong peak at ca. 0.3 eV. This characteristic is a consequence of the systematic remotion of saturated carbon chains, and the inclusion of oxygen atoms. These results can help to understand biological processes involving these molecules besides designing new devices for applications in molecular electronics.

Perfluorocarbons in Chemical Biology.

Perfluorocarbons, saturated carbon chains in which all the hydrogen atoms are replaced with fluorine, form a separate phase from both organic and aqueous solutions. Though perfluorinated compounds are not found in living systems, they can be used to modify biomolecules to confer orthogonal behavior within natural systems, such as improved stability, engineered assembly, and cell-permeability. Perfluorinated groups also provide handles for purification, mass spectrometry, and 19 F NMR studies in complex environments. Herein, we describe how the unique properties of perfluorocarbons have been employed to understand and manipulate biological systems.

Selective synthesis of new sugars based on 8-hydroxyquinoline as corrosion inhibitors for mild steel in HCl solution-effect of the saturated hydrocarbon chain: Theoretical and experimental studies

New glucose derivatives based on 8-hydroxyquinoline have been prepared, and characterized by infrared (IR), and nuclear magnetic resonance (1H and 13C NMR). These compounds were tested as a corrosion inhibitors of mild steel in 1.0 M HCl medium, using mass loss (ML), Potentio-dynamic polarization (PDP), electrochemical impedance spectroscopy (EIS), density functional theory (DFT) and monte carlo simulation (MCS). The surface of the steel after corrosion test has been characterized by scanning electron spectroscopy (SEM) coupled with energy dispersive spectroscopy (EDS). The corrosive solutions have been characterized by UV–visible spectrometry (UV–vis). The inhibitory efficacy increases with decreasing temperature and increases with inhibitor concentration and reached to 96.5% for the best inhibitor at 298 K and the optimum concentration (1 × 10−3 M). The results of the studies show that these compounds are effective in the corrosion inhibition of mild steel, and the inhibition efficiency depends on the length of the saturated carbon chain. The polarization study shows that the two inhibitors act as mixed type inhibitors. The results of thermodynamic studies show that the two compounds are absorbed on the metal surface by chemical bonds (Chemisorption) following Langmuir isotherm. UV–visible analysis shows that the two compounds capable of forming chemical bonds with the iron metal. The theoretical studies are in good agreement with those of the experimental studies.

Enhancing anti-reflective and hydrophobic properties of glass surfaces by nanostructuration and grafting of saturated carbon chains

Herein we designed a simple method to fabricate an anti-reflective and hydrophobic glass surface, which used multistep strategy. Glass surface was nanotextured by etching process, using a facile hydrothermal processing, based on the interaction between ammonium hydroxide (NH4OH) and glass surface. Amine terminations were generated by silanization of the nanostructured glass surface using 3-aminopropyltriethoxysilane (APTES). Octa-decanoic acid was anchored on the amine nanotextured glass surface by using N-hydroxysuccinimide (NHS) in the presence of the coupling agent N-ethyl-N-(3-dimethylaminopropyl) carbodiimide (EDC) leading to saturated long carbon chains terminations on the glass surface.The surface characterizations of the glass samples and the effect of the molar concentration of the grafted acid were carried out, after each modification, by Fourier Transform Infrared Spectroscopy analyzes in ATR geometry (ATR-FTIR) and the transmittance of the glass was measured by UV–Visible spectroscopy. Scanning Electron Microscopy (SEM) was used to perform the morphology observations of the samples after etching. Surface hydrophobicity was assessed by contact angle measurements.A decrease in the wettability accompanied with an increase in transmission of nanotextured glass surfaces was noticed after grafting of octadecanoic acid on the surface of the textured glass, which attest the success of the acid grafting process, established in this study, to elaborate hydrophobic and anti-reflective layers.

Catalyst- and Etchant-Dependent Mechanisms of Single-Walled Carbon Nanotube Nucleation during Chemical Vapor Deposition

Recent experiments have shown that single-walled carbon nanotube (SWCNT) chirality and diameter can be modulated by adjusting the carbon/hydrogen chemical potentials at the catalyst surface and also by adding chemical etchants, such as ammonia, to the chemical vapor deposition (CVD) feedstock. Here, we present nonequilibrium quantum chemical molecular dynamics simulations showing how these factors control the SWCNT nucleation mechanism in different ways on Fe and Ni catalyst nanoparticles. Polygonal carbon rings form on Ni catalysts via the collapse of extended, partially saturated carbon chains that are adsorbed weakly to the catalyst surface, while SWCNT nucleation on Fe is strongly mediated by the catalyst surface. The weaker Ni–C interaction here means that the carbon desorption rate, and hence carbon chemical potential, on Ni is consistently lower than it is on Fe. Ni also activates adsorbed C–H and N–H bonds more effectively than Fe. Nevertheless, the hydrogen chemical potential is consistently lowe...

First-principle study on the conductance of benzene-based molecules with various bonding characteristics

Electron transport through benzene-based molecule is the fundamental issue of the electrical properties of graphene and other conjugated π-systems. To improve the device performance of conjugated π-systems, we designed a series of benzene models and analyzed the effect of bonding environments on the molecular conductance of benzene. By combing density functional theory and the non-equilibrium Green’s function method, it is found that the conductance of isolated benzene in a saturated sp3 carbon chain is a little higher than that in a conjugated sp2 oligophenyl chain, due to its lower attenuation with increasing unit number. The intermolecular d-p-π coupling acts as an important positive factor favoring to improve the conductance, whereas the d-p-σ decoupling is a negative factor to reduce the conductance. In conjugated π-systems, the intramolecular π-π conjugation has enhanced by the increasing unit number, which is another positive factor contributing to the high conductivity with long molecular length. These analyses not only help to enrich our knowledge about electron transport through conjugated π-systems, but also guide the design of graphene-based electronic devices.

The Use of a Saturated Long Carbon Chain Sodium Monocarboxylate for the Corrosion Inhibition of Lead Objects in Atmospheric Conditions and in Acetic Acid Corrosive Solutions

In this paper, a saturated long carbon chain sodium monocarboxylate containing 18 carbons—labeled NaC18—was used for the formation of a lead carboxylate coating to inhibit the corrosion of lead in atmospheric conditions and in acetic acid corrosive solutions. The effect of stirring of the coating solution during the coating process on the inhibition efficiency was studied. The coating was characterized by scanning electron microscopy and Fourier transform infrared spectroscopy which have confirmed a formation of lead carboxylate layer on the lead metal surface. The corrosion inhibition properties of the coating were tested using linear sweep voltammetry and electrochemical impedance spectroscopy in a solution simulating the atmospheric conditions and in an acetic acid corrosive solution. Results show that the lead carboxylate forms a protective barrier that inhibits corrosion of lead in atmospheric conditions and in acetic acid corrosive solutions.