Branched-chain Hydrocarbons Research Articles

Examining amino acids as environmentally friendly corrosion inhibitors for Cu and Co chemical mechanical planarization

Aliphatic amino acids (AAs) were investigated as environmentally friendly alternatives to benzotriazole (BTA) in the chemical mechanical planarization (CMP) process for Cu interconnects. The study evaluated the corrosion resistance, galvanic corrosion, and polishing removal rates (RR) for Cu and Co in a silica-based slurry containing methionine, glutamic acid, and leucine. Corrosion characteristics were determined using linear sweep voltammetry, and the removal rate was assessed by polishing wafers under controlled CMP conditions. Metal surfaces were analyzed by X-ray photoelectron spectroscopy, and scanning electron microscopy. Results indicated that the distinctive functional groups in the amino acids influenced corrosion and polishing behaviors driven by different Cu species in the passivating film layer. Methionine with its sulfur-containing side chain, exhibited exceptional inhibition capabilities by stabilizing Cu(Ⅰ) species compared to Cu(Ⅱ), involving a combination of physisorption and chemisorption. It also effectively controlled Cu-Co galvanic corrosion with a low igc = 0.9 μA/cm². Leucine, with its branched hydrocarbon chain, mitigated Cu corrosion through physisorption (20.5 kJ/mol), but increased galvanic corrosion for Co (igc = 45 μA/cm²). Leucine formed a thin passive layer that easily broke down during the Cu(I) to Cu(II) transition. Glutamic acid, with its additional carboxylic acid group, was not effective as a corrosion inhibitor but showed a relatively low |∆Ecorr| = 5 mV. Metal removal rates of Cu and Co followed the same trend with corrosion results. The selectivity of Cu:Co:TEOS removal with methionine was more comparable than that achieved with other additives, beneficial for Cu barrier CMP.

The Response Surface Methodology for Assessment of HLB Values of Mixtures of Non-Ionic Surfactants Using Parameters from Their π-A Isotherms.

The aim of the work was to determine important parameters of the course of π-A isotherms, which can determine the HLB (hydrophilic-lipophilic balance) value of surfactant mixtures with selected structural features, such as a straight or branched hydrocarbon chain and a double bond, using RSM (response surface methodology) computational methods. Mixtures of surfactants derived from fatty acids and sorbitan with specific HLB values were evaluated by Langmuir trough. The resulting elasticity modules (ELM) and molecules surfaces (SAM) were evaluated via response surface methodology and respective equations were calculated. The π-A isotherm determined in a Langmuir trough and the ELM and SAM parameters determined on the basis of this isotherm may be useful for determining the HLB of a fixed surfactant mixture. The RSM method used, in which ELM and SAM were assumed as two independent variables, can be a useful technique for tracking the influence of individual molecular characteristics on the hydrophilic-lipophilic properties of mixtures of surfactant compounds. Changes in HLB as a dependent variable can be described as a function of ELM and SAM.

Predicting hydrogenolysis reaction barriers of large hydrocarbons on metal surfaces using machine learning: Implications for polymer deconstruction

Calculating activation energies of chemical reactions for large reaction networks is computationally demanding. Traditional Brønsted-Evans-Polanyi (BEP) relationships are useful in this regard but are prone to substantial estimation errors. Here, we explore machine learning models to predict activation energies for hydrogenolysis reactions on transition metals, including Ru, Pt, and Rh. The curated dataset includes 380 DFT-calculated activation energies of C-C and C-H scission reactions ranging from C1 to C6 species. The mean absolute error of traditional BEPs is 0.30 eV, and published BEPs on smaller hydrocarbons give even larger errors. In comparison, an XGBoost model achieves a mean absolute error of 0.19 eV for the test set without needing additional DFT-calculated energies. The model selects the homologous series among reactions and the electronegativity and atomic mass of the metal atoms as key features. The model appears transferable across metals. This approach can provide accurate and rapid estimation of activation energies of large reaction networks, such as those in plastics recycling, to accelerate catalyst screening. We showcase the impact of hydrocarbon chain length and branching on the barriers, discuss implications for the depolymerization rate of isotactic polypropylene and low vs. high-density polyethylene, and demonstrate the feasibility of hydrogenolysis catalyst screening.

THERMODYNAMICS OF LIQUID–GAS PHASE EQUILIBRIA OF DIISOPROPYLSULFOXIDE–WATER SYSTEM

The saturated vapor pressure of diisopropylsulfoxide aqueous solutions was measered at temperatures of 303.15 K and 308.15 K. It was shown that the total saturated vapor pressure increases with decreasing diisopropylsulfoxide concentration in the solution and with increasing temperature. As in the cases of diethylsulfoxide and dipropylsulfoxide aqueous solutions, a negative deviation from Raoult’s law is also observed. This confirms the ability of diisopropylsulfoxide molecules to associate with water molecules. Based on the results obtained, the partial pressures, the activity coefficients of diisopropylsulfoxide and water and the excess Gibbs energy of their mixing, were calculated. It is shown that the excess Gibbs energy of mixing is negative and reaches its minimum value at a mole fraction of diisopropylsulfoxide equal to 0.38. The obtained data on the excess Gibbs energy of mixing DiPSO and water were treated using the Redlich–Kister equation. It has been established that the interaction between the molecules of diisopropylsulfoxide and water is stronger than in the diethylsulfoxide+water system, and weaker than in the dipropylsulf-oxide+water system. This fact can be explained by an increase in the electron-donating ability of the alkyl group with increasing hydrocarbon chain length, which increases the reactivity of the oxygen atom of the sulfoxide group. As a result, when moving from diethylsulfoxide to diisopropylsulfoxide or dipropylsulfoxide, the ability of their molecules to interact with water molecules to form hydrogen bonds increases. At the same time, a decrease in hydrophobic effects and dispersion forces between diisopropylsulfoxide molecules with a branched hydrocarbon chain leads to a weakening of the interaction between molecules in the diisopropylsulfoxide+water system compared to the dipropylsulfoxide+water system, which is also observed experimentally.

Efficiency estimates for electromicrobial production of branched-chain hydrocarbons

In electromicrobial production (EMP), electricity is used as microbial energy to produce complex molecules starting from simple compounds like CO2. The aviation industry requires sustainable fuel alternatives that can meet demands for high-altitude performance and modern emissions standards. EMP of jet fuel components provides a unique opportunity to generate fuel blends compatible with modern engines producing net-neutral emissions. Branched-chain hydrocarbons modulate the boiling and freezing points of liquid fuels at high altitudes. In this study, we analyze the pathways necessary to generate branched-chain hydrocarbons invivo utilizing extracellular electron uptake (EEU) and H2-oxidation for electron delivery, the Calvin cycle for CO2-fixation and the aldehyde deformolating oxygenase decarboxylation pathway. We find the maximum electrical-to-fuel energy conversion efficiencies to be and . For a model blend containing straight-chain, branched-chain, and terpenoid components, increasing the fraction of branched-chain alkanes from zero to 47% only lowers the electrical energy conversion efficiency from to .

Environmentally Friendly Amino Acid-Based Polishing Slurry with Reduced Galvanic Corrosion at Copper/Cobalt Interface for Advanced Cu Interconnect Applications

Chemical mechanical planarization (CMP) is an integral part in semiconductor processing including the back-end-of-line (BEOL) step. A goal of CMP is to uniformly polish the metal interconnects and the liner/barrier materials while minimizing CMP-related defects such as pitting, dissolution, and galvanic corrosion. A variety of azoles are used as corrosion inhibitors such as benzotriazole (BTA) to prevent corrosion defects during polishing. [1,2] These azoles work together with particles in the slurries to polish the overplated metal forming the interconnects. However, azoles are very poorly biodegradable during wastewater treatment and highly toxic to the nitrification process, which requires expensive wastewater treatment challenges.[3,4] Also, it is known that the use of BTA leads to contamination of Cu films by forming undesirable hydrophobic organic residues (e.g., BTA and Cu-BTA complexes),[5] making their removal very difficult during cleaning. To address these challenges aliphatic amino acids were examined as potential corrosion inhibitors to replace problematic azoles in CMP slurries.Three amino acids were considered in a model CMP slurry. These three were chosen for their unique functional groups: methionine, containing a sulfur group, glutamic acid, having an extra carboxylic acid group, and leucine, having a branched hydrocarbon chain. A representative polishing slurry with 35 nm colloidal silica abrasives, 1 wt% hydrogen peroxide as an oxidizer, 0.5wt% arginine as a complexing agent, at pH 8 was used. Three experimental aims were considered (1) corrosion characterization of the three amino acid and BTA electrolytes with linear sweep voltammetry; (2) comparison of the Co and Cu metal removal rate (MRR) in polishing experiments with a proto-type CMP polisher with 8” wafers, and (3) oxidation of the amino acids and BTA in a Fenton assisted electrooxidation reaction. Methionine was most effective in controlling the galvanic corrosion of the Cu-Co couple. The Co and Cu MRR decreased in the presence of three amino acids and showed comparable removal selectivity. The forced degradation of the amino acids under the Fenton-assisted electrooxidation confirmed that they were more readily degraded compared to BTA. Acknowledgments: This work was supported by the Semiconductor Research Corporation grant (Task 3100.001) under the Global Research Collaboration program. References Seo, J., A review on chemical and mechanical phenomena at the wafer interface during chemical mechanical planarization. Journal of Materials Research 2021, 1-23.C. Peethala, H. P. Amanapu, U. Lagudu, and S.V. Babu, J. Electrochem. Soc, 159(6), H582-H588, 2012.D.E. Speed, Chapter 11, Advances in chemical mechanical planarization (CMP) 2nd edition, Babu, S. V., Ed. 2021.G. Li et al. / Chemosphere 241 (2020) 1249932.Seo, J.; Vegi, S. S. R. K. H.; Babu, S.V. ECS Journal of Solid State Science and Technology 2019, 8 (8), P379–P387.

Organic matter degradation determines the concentrations of polybrominated diphenyl ethers in sediments. Multivariate learning on environmental and experimental models

Sediment organic matter (SOM) plays an important role in capturing polybrominated diphenyl ethers (PBDEs) due to its affinity to hydrophobic and lipophilic compounds. Previous publications about correlations between PBDE concentrations and SOM content showed discrepancies among the results, reporting either significant positive correlations or no correlations at all. This work aimed to provide a deeper insight into SOM characteristics that might determine the concentrations of PBDEs in sediments. Sediment samples from Mendoza province, Argentina, were analyzed to contrast two models, environmental and experimental, using multivariate learning methods. Mendoza has been going through increasing events of drought and water scarcity, hence the occurrence, transport, and fate of contaminants as PBDEs in aquatic environments is of superlative importance. Principal component analysis (PCA) and partial least squares regression (PLS) were used to evaluate the correlations between physicochemical properties of sediments, semi-quantitative Fourier transform infrared (FTIR) area ratios obtained from SOM spectra, and PBDE concentrations in sediments. Moreover, a linear model was proposed to determine SOM density using FTIR area ratios and it was used as an additional variable in multivariate analyses. The results obtained from PCA and PLS were consistent and revealed that PBDE concentrations in sediments were correlated with a more degraded SOM, characterized by shorter and more branched hydrocarbon chains. PBDE concentrations were also correlated with higher SOM density values, which in turn were correlated with SOM degradation. These findings extend previous understanding and emphasize that not only is the organic matter content a factor in determining PBDE concentrations in sediments, but also and more significantly, its degree of degradation.

Non-catalytic and Catalytic Pyrolysis of Low Density Polyethylene LDPE Plastic Waste Into Fuel Ranged Hydrocarbons Using Nigerian Local Clay Composites

Plastic utilisation and plastic waste accumulation is rising in recent times mostly in developing countries. The utilization of modified and unmodified Nigerian bentonite clay as catalyst for preparation of fuel-ranged hydrocarbons from low-density polyethylene (LDPE) sachet wastes by pyrolysis was investigated. Pyrolysis of LDPE was done using locally fabricated semi-batch reactor condenser column. The products were characterized using Fourier transform infra-red spectroscopy (FTIR) and gas chromatograph with a flame ionisation detector (GC-FID). Physicochemical properties of the products were determined using standard analytical methods. The products from non-catalysed contained mostly saturated hydrocarbons compared to that of the catalytic process which contained more branched-chain hydrocarbons and mono-substituted aromatics. Physicochemical properties of the product from non-catalytic process showed resemblance to those of kerosene and diesel fuel while the properties of products from catalytic pyrolysis closely approximates those of commercial gasoline. This implies that the catalytic process gave products that were more suitable as fuels for auto engine which require higher octane number based on their naphthenic and aromatic content.

Harringtonine Ester Derivatives with Enhanced Antiproliferative Activities against HL-60 and HeLa Cells.

Harringtonine (HT), produced from Cephalotaxus species, is known to exhibit potent antiproliferative activity against myeloid leukemia cells by inhibiting protein synthesis. A previous study using acute promyelocytic leukemia (HL-60) cells raised the possibility that the C-5' methyl group of HT plays an important role in regulating leukemia cell line antiproliferative activity. In order to investigate the effect of hydrocarbon chains at C-5' on the resultant activity, the C-5' methyl group was replaced with various straight- and branched-chain hydrocarbons using the corresponding alcohols, and their antiproliferative activity against HL-60 and HeLa cells was investigated. As a result, 4'-n-heptyl-4'-demethylharringtonine (1f, n-heptyl derivative) showed the most potent cytotoxicity among the HT ester derivatives produced, with IC50 values of 9.4 nM and 0.4 μM for HL-60 and HeLa cells, respectively. Interestingly, the cytotoxicity of derivative 1f against HL-60 and HeLa cells respectively was ∼5 (IC50 = 50.5 nM) and ∼10 times (IC50 = 4.0 μM) those of HT and ∼2 (IC50 = 21.8 nM) and ∼4 times (IC50 = 1.7 μM) more than homoharringtonine (HHT). These results demonstrate the potential of the derivative 1f as a lead compound against leukemia.

Unravelling the performance of oxycarbonyl-thiocarbamate collectors on chalcopyrite using first-principles calculations and micro-flotation recoveries

First-principle quantum mechanical density functional theory (DFT) was employed to explore the bonding behaviour, adsorption energies and electronic properties directly related to the reactivity’s of O-butyl-N-ethoxycarbonyl-thiocarbamate (BECTC), O-isobutyl-N-ethoxycarbonyl-thiocarbamate (IBECTC), O-butyl-N-butoxycarbonyl-thiocarbamate (BBCTC), O-isobutyl-N-butoxycarbonyl-thiocarbamate (IBBCTC), and O-isobutyl-N-isobutoxycarbonyl-thiocarbamate (IBIBCTC) with the chalcopyrite (CuFeS2) (112) surface and complimented by micro-flotation recoveries of the chalcopyrite. The partial density of states (PDOS) of the isolated oxycarbonyl-thiocarbamate collector showed that the sulphur atom (S1) was more active and will be more reactive during adsorption. Adsorption of the oxycarbonyl-thiocarbamate collectors preferred the Cu atom over Fe atoms. The adsorption energies and micro-flotation recoveries yielded similar trends and the order followed: BBCTC > IBIBCTC > BECTC > IBBCTC > IBECTC, which showed that BBCTC exhibited the strongest exothermic adsorption. This showed that the adsorption energies that determined how a collector binds to the mineral surface can predict the flotation recoveries. The PDOS and atomic population charges after adsorption showed that both Cu and S1 atoms lose charges (electron donor) forming σ-bonds, and simultaneously, dative π-bonds. The results also showed that BBCTC and BECTC are better collectors for the selective flotation of chalcopyrite minerals and indicated that a straight hydrocarbon chain gave stronger adsorption than a branched hydrocarbon chain.

Portable Electronic Nose for Analyzing the Smell of Nasal Secretions in Calves: Toward Noninvasive Diagnosis of Infectious Bronchopneumonia.

The paper demonstrates a new approach to identify healthy calves (“healthy”) and naturally occurring infectious bronchopneumonia (“sick”) calves by analysis of the gaseous phase over nasal secretions using 16 piezoelectric sensors in two portable devices. Samples of nasal secretions were obtained from 50 red-motley Holstein calves aged 14–42 days. Calves were subjected to rectal temperature measurements, clinical score according to the Wisconsin respiratory scoring chart, thoracic auscultation, and radiography (Carestream DR, New York, USA). Of the 50 calves, we included samples from 40 (20 “healthy” and 20 “sick”) in the training sample. The remaining ten calves (five “healthy” and five “sick”) were included in the test sample. It was possible to divide calves into “healthy” and “sick” groups according to the output data of the sensor arrays (maximum sensor signals and calculated parameters Ai/j) using the principal component linear discriminant analysis (PCA–LDA) with an accuracy of 100%. The adequacy of the PCA–LDA model was verified on a test sample. It was found that data of sensors with films of carbon nanotubes, zirconium nitrate, hydroxyapatite, methyl orange, bromocresol green, and Triton X-100 had the most significance for dividing samples into groups. The differences in the composition of the gaseous phase over the samples of nasal secretions for such a classification could be explained by the appearance or change in the concentrations of ketones, alcohols, organic carboxylic acids, aldehydes, amines, including cyclic amines or those with a branched hydrocarbon chain.

Fatty acids of microalgae: diversity and applications

The possibility of obtaining commercially valuable products from microalgae stimulates scientific research in this direction. The ability of microalgae to accumulate lipids is very promising from the point of view of practical application. The diversity of the composition of microalgae lipids makes it possible to study a wide range of their applications: biofuel production, food products, feed for farm animals and birds, for aquaculture, food additives, etc. Fatty acids (FAs) are involved in the metabolic pathways of formation and conversion of most lipid classes, and their composition largely determines their properties and practical use. As a result, much attention is paid to the study of the composition of fatty acids in microalgae (including cyanobacteria). This review summarizes information on the diversity of the fatty acid composition of microalgae and cyanobacteria, taking into account their rare and unusual categories. The total variety of FA profile of microalgae from different habitats is formed by 135 FAs. Taking into account the length of the hydrocarbon chain, its structure and the presence of substituents, they are distributed into several groups: with an even number of carbon atoms in the chain—81 (short-chain FAs—2, medium-chain FAs—14, long-chain FAs—28, very-long-chain FAs—37), with an odd number of carbon atoms—33, with a branched hydrocarbon chain and additional functional groups—21. Among FAs of microalgae there are both saturated and unsaturated FAs with different numbers of double bonds: saturated FAs—19, monounsaturated FAs—26, polyunsaturated FAs—68. The FA profile of microalgae is rich in omega-3 and omega-6 fatty acids. The review also considers the use of fatty acids as an industrial resource, as well as a biomarker.

Meibum lipid hydrocarbon chain branching and rheology after hematopoietic stem cell transplantation

PurposeMeibum from donors who have had hematological stem cell transplantations (MHSCT) are susceptible to severe dry eye symptoms and exhibit very high lipid order (stiffness) compared with meibum from donors without dry eye (Mn). Since lipid order could have functional consequences, we compared the rheology and composition of Mn and MHSCT to measure meibum compositional, structural and functional relationships. MethodsThe rheology and composition was measured using Langmuir trough and 1H NMR spectroscopy, respectively. ResultsMHSCT and Mn was studied from 16 to 43 donors, respectively, using NMR spectroscopy. MHSCT contained significantly 16% more straight chain and 24% less iso-chain hydrocarbons compared with Mn. The cholesteryl ester to wax ester molar ratio, and hydrocarbon chain unsaturation were not significantly different, for MHSCT compared with Mn.Surface pressure-area isotherms of meibum from 30 donors without dry-eye were grouped into 4 pools (PC) and meibum from 32 donors with dry eye who had hematopoietic stem cell transplantation (PT) were grouped into 3 pools. Above 15 years of age the Пmax and (Cs−1)max increased with age for both the PC and the PT cohorts. (Cs−1)max values were higher for PT samples compared with age matched PC samples, indicating they had higher elasticity and stiffness. A more ordered lipid could contribute to the formation of a discontinuous patchy tear film lipid layer, which in turn results in deteriorated spreading, and decreased surface elasticity. ConclusionsThe composition and rheology of meibum from donors with dry eye and who have had HSCT support the idea from other studies that more ordered meibum may contribute to or be a marker of dry eye.

Confinements on growth sites of Fischer-Tropsch synthesis, manifesting in hydrocarbon-chain branching – Nature of growth site and growth-reaction

Confinements on growth sites are recognized as essential principle of Fischer-Tropsch synthesis. Chain branching is sensitive against chain size. Similarities between FT-growth-sites and homogeneous pincer-complex catalysts are realized.In house developed methods for time resolved investigation of activity and selectivity are applied. An advanced ASF-model is defined, and on this basis probabilities of branching are calculated from experimental product distributions. Chain-length dependence in branching is quantified as branching pattern. Confinements on branching are studied for iron- and cobalt catalyst at varied CO partial pressure and during catalyst restructuring.With cobalt, FT-growth sites are observed as of dynamic nature, CO being involved. With iron, growth sites are stable, even during catalyst carbiding. The basic parameter to constitute a FT-growth site, be it on iron or cobalt, are specific confinements, regardless of differences in chemical or structural nature. Results and discussion of this work are aiming at disclosing the miracle of “gasoline synthesis from CO + H2 at normal pressure”, invented by Franz Fischer and Hans Tropsch, as the methylene insertion on homogeneous-complex-alike sites on the catalyst surface.

Thermal decomposition mechanism of some hydrocarbons by ReaxFF-based molecular dynamics and density functional theory study

In order to investigate the decomposition mechanism of hydrocarbons, pyrolysis processes of 11 typical hydrocarbons (isobutane, isopentane, isohexane, n-butane, n-pentane, n-hexane, cyclobutane, cyclopentane, cyclohexane, benzene and toluene) are performed by using ReaxFF MD and DFT method. The results show that the initial pyrolysis reactions of these hydrocarbons can be divided into two types: homolytic cleavage of C–H bond and C–C bond. The bond dissociation energies of C–H bonds are higher than that of C–C bonds in these hydrocarbons except for toluene. The thermal decomposition rates of branched-chain hydrocarbons are faster than that of straight-chain hydrocarbons. The thermal decomposition rates of chain hydrocarbons gradually increase with the increases of C atom number. The main product molecules of hydrocarbon pyrolysis are H2, CH4, C2H2 and C2H4. The apparent activation energies of 4 hydrocarbons (n-pentane, isohexane, neopentane and cyclopentane) pyrolysis are calculated by the kinetic analysis. In further reactions, CH3, C2H5 and H radicals are collided with hydrocarbons to undergo H-abstraction reactions. The energy barriers of H-abstraction reactions are calculated by DFT.

Absolute Prediction of the Melting and Freezing Points of Saturated Hydrocarbons Using Their Molar Masses and Atume’s Series

This study was conducted to apply the Atume’s series in the absolute prediction of melting and freezing points of a wide range of saturated liquid and solid hydrocarbons. The calculated results that were obtained, shows that a range of 92% to 99% accuracy was theoretically achieved when compared to experimental results. Basically, precise interpolations were deployed by equating the energies released by frozen liquid molecules to the energies absorbed by their corresponding boiling molecules; which represents their lower and upper energy fixed points respectively. These two fixed points were also found to vary infinitesimally and inversely to each other. The energies absorbed or released, molar masses, and trigonometric properties formed the basis for this method. In branched chain hydrocarbons, the melting points of their corresponding linear molecules were also used as reference points to determine their melting and freezing points; indicating the mathematical relationships between their fixed points and trigonometric properties.

GC-MS analysis of bioactive compounds from Freshwater mussels of Parreysia corrugata (Muller 1774) and their pharmacological activities

GC-MS is one of the best techniques to identify the constituents of volatile matter, long chain, branched chain hydrocarbons, alcohols acids, esters etc. The freshwater mussels Parreysia corrugata was analyzed using Gas Chromatography–Mass Spectrometry, while the mass spectra of the compounds found in the extract was matched with the National Institute of Standards and Technology (NIST) library. Gas chromatography mass spectrometry (GC-MS) analysis revealed the presence of 26 compounds. The compounds were identified by comparing their retention time and peak area with that of literature and by interpretation of mass spectra. The first compound identified with less retention time (30.236 min) was 2,6-Difluorobenzoic acid, tridec-2-ynyl ester, whereas gamma.-Tocopherol was the last compound which took longest retention time (29.84min) to identify. Many of them are used in industry for various applications like flavor, antioxidant, anti-inflammatory, antimicrobial, pesticide and cancer preventive. Keywords: Freshwater mussels, Parreysia corrugata, GC-MS, Bioactive components

Epoxy Cross-Linked Polyamine CO2 Sorbents Enhanced via Hydrophobic Functionalization

Optimizing sorption capacity and amine efficiency are among the major challenges in developing solid carbon dioxide sorbents. Such materials frequently feature polyamines impregnated onto supports adding weight to the sorbents. This work presents the cross-linking of polyethyleneimine (PEI) by the industrially available epoxy resin, bisphenol-A diglycidyl ether (DER) to form support-free sorbent materials. Prior to cross-linking, the polyamine chain is functionalized with hydrophobic additives; one material modified with the branched chain hydrocarbon 2-ethylhexyl glycidyl ether displays a CO2 uptake of 0.195 g/g, 4.43 mmol CO2/g (1 atm single component CO2, 90 °C). The additive loading affects the cross-linking, with the lesser cross-linked materials showing more favorable sorption capacities and higher amine efficiencies. The type of additive also influences sorption, with the larger, longer and bulkier additives better able to free the amines from their hydrogen bonding network, generally promoting bet...

Modification of hydrophilic amine-functionalized metal-organic frameworks to hydrophobic for dye adsorption

The competitive adsorption of water restricts the practical performance of metal-organic frameworks (MOFs) for organic dye removal. Here, we paid attention to tuning the hydrophobicity of MOFs for dye adsorption. By introducing highly branched hydrocarbon chains, a super-hydrophobic MOF with a contact angle 158° is obtained using a post-synthetic pathway. At the same time, the crystallinity, thermostability can be well maintained, and the surface area is as high as 615 m2 g−1. The superhydrophobic MOFs exhibit improved dye adsorption efficiency, and more than 99% Rhodamine 6G can be adsorbed within 10 min while only 52% for the pristine one. Upon adsorption equilibrium, the adsorption capacity of the hydrophobic MOFs reaches 478 mg g−1, much higher than that of the pristine hydrophilic ones (243 mg g−1).

Human meibum chain branching variability with age, gender and meibomian gland dysfunction

NMR spectroscopy was used to measure hydrocarbon chain branching variability in meibum with age, gender and Meibomian gland dysfuction (MGD). A cohort of 65 meibum donors without dry eye and 31 donors with MGD was studied. Heteronuclear 2D NMR was used to confirm CH3 resonance assignments allowing us to positively identify 23 of the 27 proton resonances of cholesteryl ester and 1H resonances due to straight chain, iso-branched and anteiso-branched hydrocarbons. Meibum from donors without dry eye contained 57 ± 1% straight-chains, 23 ± 1% iso-branched chains and 20 ± 1% anteiso-branched hydrocarbon chains. Compared with meibum from donors without dry eye, meibum from donors with MGD contained less, 50 ± 2% straight-chains, more, 32 ± 2% iso-branched chains and the same amount, 18.0 ± 0.07%, of anteiso-branched hydrocarbon chains. Meibum hydrocarbon chain branching did not change with age between 22 and 68 years of age, nor was it influenced by gender. Based on previous studies, one would expect anteiso-branched chains would contribute to lowering the phase transition temperature of meibum, decrease the elasticity of the tear film lipid layer and increase the molecular area and spreading of meibum on the surface of the eye. Although we speculate that the observed differences in iso-chain branching do not influence tear film stability or rheology, the speculation has yet to be tested.