Mixed Esters Research Articles

Enzyme-catalyzed preparation of polyol ester lubricants and performance research-based on pelargonic acid, oleic acid and trimethylolpropane

Chemical oil esters synthesized by polyols and fatty acids are biodegradable and have ideal physicochemical and lubricating properties as compared to mineral lubricants. Using sulfuric acid and lipases as catalysts, a polyester lubricant was synthesized from pelargonic acid (PA) and trimethylolpropane (TMP). Lipase-catalyzed goods are superior and more in accordance with green production requirements. The optimized reaction conditions of lipase catalytic were 50 °C, 15%wt enzyme content, PA: TMP= 3.3:1 %, and 15 % water content. When the time reached 96 h, the accumulation of trimethylolpropane (TMPTP) reached 82% under these conditions. The TMPTP purified by molecular distillation has a flashpoint of 276 °C, a pour point of − 57 °C, and a viscosity index of 145, making it more suitable for extreme environments. On this basis, to improve the viscosity-temperature performance of the substrate, a certain proportion of oleic acid (OA) is added. Low viscosity (kinematic viscosity of 4.86–9.54 mm2/s at 100 °C), high viscosity index (VI > 160), low pour point (−50 °C), and low friction coefficient (COF) of 0.09 ∼ 0.11 is among the properties of a series of synthetic hetero-chain mixed esters, which can meet the needs of a variety of extremely low temperatures and complex working conditions.

Reduced graphene oxide/FeOOH-based asymmetric evaporator for the simultaneous generation of clean water and electrical power

As one of the ways to comprehensively utilize solar energy, solar-driven interfacial evaporation displays promising opportunities to alleviate both freshwater and energy shortages. However, there is always a partial impairment of solar energy utilization during evaporation, and its operation is stagnant without sunlight. In this study, a novel asymmetric evaporator is designed that achieves the maximum utilization of solar energy for clean water and power output by two-step asymmetric filtration of reduced graphene oxide/FeOOH (RGO/FeOOH)-based composites and graphene oxide (GO) on a mixed cellulose ester membrane (MCE). Under one solar irradiation, the RGO/FeOOH-based asymmetric evaporator can achieve an average output power of 51.33 mW m−2 synchronously with efficient solar evaporation. The output voltage can reach up to 640 mV with a current of approximately 84.8 μA. Furthermore, the average output power of this evaporator is 26.96 mW m−2 under ambient conditions. A light-emitting diode (LED) can be successfully lit via a series connection of electricity generators. The RGO/FeOOH-based asymmetric evaporator can function full-time with only solar energy and water, demonstrating the potential to generate steam and electricity simultaneously in sunlight; the findings also show its value as a generator on cloudy days or at night. Moreover, the RGO/FeOOH-based composites also show the photocatalytic degradation capabilities of organic pollutants in water. The simple fabrication strategy and superior thermal and electrical performance of the solution indicate that these novel RGO/FeOOH-based composites can be used for power generation, energy storage and brine and wastewater purification to achieve the maximum utilization of resources.

Measuring the Concentrations of Asbestos Fibers in Some Crowded Areas of Baghdad in The Summer of 2020

Aims of this research to determine asbestos fibers levels in surrounding air of some crowded sites of Baghdad city were monitored in summer 2020. Collection of samples was conducted by directing air flow to a mixed cellulose ester membrane filter mounted on an open‑faced filter holder using sniffer a low flow sampling pump, samples of air were collected from five studied areas selected in some heavy traffic areas of Baghdad city, (Al-Bayaa and Al-Shurta tunnel, Al-Jadriya, and Al-Meshin commercial complex, control), then analyzed to determine concentrations of asbestos fibers. Counting of asbestos on the filters was carried out through using both scanning electron microscope SEM and an energy dispersive X‑ray system EDS to count and determine asbestos fibers. The results of this research appeared that the levels of asbestos fibers which recorded minimum value in control site was 0.018±0.001 f/ml and maximum value in Al-Gadriya was 0.121±0.006 f/ml. The concentrations of asbestos fibers in all studied areas were more than standards of world health organization WHO for air was 0.0022 f/ml. This may be because the presence of crowded traffic, occurrence of industries near studied areas. Therefore, effective plans like management of traffic, changing of industrial locations, and products substitution replacement can be effective in reduce concentrations of asbestos fibers. Keywords: Asbestos Fibers, SEM, Crowded Areas, Ambient Air, Summer.

Inkjet-printed colorimetric sensor array for the rapid identification of adulterated Fritillariae cirrhosae bulbus

As an important antitussive and expectorant herbal medicine, Fritillariae cirrhosae bulbus (FCB) is rare and expensive, leading to massive adulterations in the market. Herein, we report a solid colorimetric sensor array (CSA) method for the rapid identification of FCB and its adulterations. This CSA was fabricated by printing nine pH indicators on a mixed cellulose ester membrane via a commercially available inkjet printer filled with polyethylene glycol-containing ink. This CSA displayed color changes to various analytes, as their solution of varied pH values triggers chemical reactions with the nine pH indicators (and other potential interactions). The digital database of these colorimetric response patterns was collected automatically using a homemade program. The outstanding identification capability of the CSA was confirmed via the analysis of 1,2-diols and catechols. The principal component analysis result demonstrated that this CSA could distinguish pure FCB powder from its six common adulterations. The linear discriminant analysis models were established for the qualitative identification of adulterated FCB samples with 89.58 %− 100 % accuracy. Furthermore, partial least squares regression models were developed for the quantitation of adulterant percentages with correlation coefficients higher than 0.87. We expect that the inkjet-printed CSA provided an effective on-site screening method for identifying adulterated FCB.

Silane-Grafted MXene (Ti3C2T X ) Membranes for Enhanced Water Purification Performance.

The current communication describes the modifications of MXene (Ti3C2Tx) with silane grafting reaction for membrane preparation for enhanced water purification. The MXene was successfully grafted with n-octadecyltrichlorosilane (MODCS), n-octyltrichlorosilane (MNOCS), and triphenylchlorosilane (MTPCS) in order to make a hydrophobic MXene that could be able to bind with the organic matrix/polymers. The modified MXenes were transformed into thin membranes by forming an MXene/polyvinyl alcohol (PVA) composite over a filter paper support, that is, MCE (mixed cellulose ester filter paper). MXene membranes were also formed without the MCE support by using PVA and glutaraldehyde (PVA/GA) where GA was used as a cross-linker to stabilize PVA and make it water-resistant. The conditions of membrane formation were optimized to investigate optimum compatible conditions with the modified materials. The resulting membranes were tested for the removal of various organic pollutants that included mesitylene (or trimethylbenzene); polyaromatic hydrocarbons (chrysene, as a model); biphenyl; bisphenol A; benzene, toluene, ethylbenzene, and styrene; methylene blue; and Sudan II dyes. The MTPCS PVA/GA cross-linked membrane showed the best results for a pollutant removal efficiency up to 98%. Overall, all six types of membranes showed the removal efficiency in the range of 52–98%. It was observed that the membrane exhibits reusability up to five cycles.

Chemically stable NH2-MIL-125(Ti)/Sep/PDA composite membranes with high-efficiency for oil/water emulsions separation

Nowadays, oily wastewater is a severe threat to the living environment of humankind. In recent years, MOF materials have shown great application potential in membrane separation and treatment of oily wastewater. In this paper, the mixed cellulose ester membrane (MCEM) was modified by polydopamine, and the NH2-MIL-125 (Ti)/Sep(sepiolite)/PDA composite membrane was prepared by simple vacuum filtration. The composite membrane had super-hydrophilic performance and underwater super-oleophobic performance, and could effectively separate oil-water emulsion separation performance. Also, the composite membrane showed good repeatability. After 10 cycles, the retention rate of petroleum ether-in-water emulsion was still more than 99%, and the flux was more than 2000 L·m−2·h−1. Since strong adhesion ability of PDA and the covalent interaction between NH2-MIL-125(Ti) and Sep, the chemically stable NH2-MIL-125(Ti)/Sep/PDA composite membrane was exposed to the strong acid (pH=1), alkali (pH=11), and salt (5% saturated NaCl) solutions showed excellent chemically stable. These outstanding properties made the composite membrane have great potential in the removal of oily wastewater.

Ti3C2/W18O49 hybrid membrane with visible-light-driven photocatalytic ability for selective dye separation

Toxic organic dyes are a serious threat to the global environment, and membranes with catalytic properties show great promise as a green water treatment method for removing these pollutants. Herein, Ti3C2/W18O49 photocatalytic membranes were constructed by vacuum filtrating Ti3C2 and W18O49 to form a hybrid layer on a mixed cellulose ester (MCE) support. The efficient separation of dyes was attributed to the negative charge and abundant –OH groups of Ti3C2/W18O49, which can capture cationic dyes by electrostatic adsorption and form hydrogen bonds with the amino groups of dye molecules. Moreover, the Ti3C2/W18O49 membrane exhibited excellent photocatalytic performance and a dye-contaminated membrane was regenerated under visible light in 120 min. The two component materials complement each other, with the W18O49 providing adsorption sites and photocatalytic ability and the Ti3C2 serving as an electron trap and improving charge separation. Photoinduced electrons in the conduction band of W18O49 are transferred to Ti3C2 to form O2–, while holes remain in the valence band of W18O49 to generate OH, and h+. O2– and OH are mainly responsible for the degradation of dyes. Therefore, this efficient and easily prepared membrane shows practical potential as a next-generation method for dye removal from water.

Synthesis of Galactomannan Sulfate-Citrate

Sulfated derivatives of polysaccharides have anticoagulant, hypolipedimic and other biological activity. In this work, a complex mixed ester of galactomannan, its sulfate-citrate, was obtained for the first time. The introduction of citrate and sulfate groups was proved by FTIR spectroscopy by the appearance of corresponding absorption bands. It was shown by X-ray diffraction that the introduction of the citrate group leads to the amorphization of the galactomannan structure.

High-Performance mild annealed CNT/GO-PVA composite membrane for brackish water treatment

Two-dimensional (2D) graphene oxide (GO)-based materials with tunable physicochemical properties have enormous potential for developing next-generation desalination membranes. Nevertheless, weak interlamellar interactions result in poor selectivity towards small ions, limiting the wide applicability of GO membranes. Controlling the swelling of the GO membrane while maintaining high permeability and selectivity is a significant scientific and technological challenge. To address the issues above, we used one-dimensional (ID) carbon nanotubes (CNT) as a nano-spacer and polyvinyl alcohol (PVA) as an adhesive. Synergistic ionic complexation between 1D-CNT, 2D-GO, and PVA was studied using various analytical techniques. The intercalation of CNT between GO nanosheets and the cross-linking of CNT/GO-PVA significantly improved the separation performance. Pressure-assisted filtration was used to coat the CNT/GO-PVA on hydrophilic mixed cellulose esters (MCE) support with pore size 0.22 µm to obtain a highly ordered laminated structure. Five minutes of mild annealing at 80 °C narrowed the laminar channels of the GO nanosheets by transforming the oxygen-containing functional groups. In a dead-end filtration unit, the CNT5/GO15-PVA0.5 composite membrane exhibits a high rejection of 94.2% to sodium sulphate (Na2SO4) and 85.86% to sodium chloride (NaCl), accompanied by a high permeate rate of 14.2–13.45 LMH at 5 bar operating pressure. The salt rejection studies were evaluated for continuous operation for 72 h for all membranes. Due to the synergistic effect of CNT, GO, and PVA, prepared membranes demonstrated the potential for practical water separation applications with desired permeability and selectivity.

Living Filtration Membranes Demonstrate Antibiofouling Properties

Membrane filters are excellent prospects for increasing global access to safe water; however, they are significantly limited by fouling, particularly biofouling. Fouling plagues membranes by reducing efficiency and increasing maintenance and costs. Biofouling is particularly problematic due to the self-replicating nature of microorganisms and the secretion of extracellular polymeric substances that make the biofilm difficult to remove. Living filtration membranes (LFMs) are a sustainable membrane technology composed of bacterial cellulose and native microorganisms. In this study, natural water from Butte, Montana’s three municipal drinking water sources (Basin Creek Reservoir, Moulton Reservoir, and Big Hole River) was pretreated with a coagulant and used in 400 min bench-scale dead-end filtration tests. Two membranes were compared─an LFM and a commercial mixed cellulose ester (MCE) membrane with a similar nominal pore size. Although the MCE membrane was more hydrophilic and had a smoother surface, surface properties that, in general, may improve fouling resistance for certain particles, a more rapid flux decline and live biomass were observed with the MCE membrane for all three waters. We suggest that the LFM’s resistance to biofouling may be due to the proliferation of native bacteria, Acetobacter, which produces acetic acid, a known antibiofilm and antibacterial agent.

Thermo-chemical transition in cellulose esters and other polymers

A peculiar thermochemical phenomenon of coexistence of chemical decomposition and material softening, observed in cellulose acetate butyrate (CAB) and named glass chemical transition is further scrutinized. It is demonstrated that cellulose acetate (CA), also, exhibits a thermo-chemical transition and that mixed esters like CAB, may exhibit more than one thermo-chemical transitions. The DSC intense endotherm below 100 °C, common in cellulose esters, is shown to arise, mainly, from esterification. The variation of the stability of the acetyl bond in CAB and CA is also analyzed. A critical discussion of these findings along with corroborating experimental data for poly(vinyl alcohol) (PVA) and literature data for vinyl polymers is presented, suggesting that the thermo-chemical transition is not a phenomenon exhibited, exclusively, by cellulose esters. Instead, it is an often-encountered phenomenon encompassing physicochemical changes and material softening at temperatures erroneously attributed to glass transitions or melting points.

Development of Culture-Independent Detection Method for Beer Spoilage Lactic Acid Bacteria

In microbiological quality control of final beer products, 100–400 ml beer samples are traditionally filtered on a membrane filter, followed by a lengthy culturing process in/on a laboratory medium that usually requires 3–14 days. This study aims to detect beer spoilage lactic acid bacteria (LAB) in a culture-independent fashion, using a direct polymerase chain reaction (PCR) approach. In order to detect a trace level of spoilage LAB in beer products, pressure cycling technology was evaluated to determine if this technology could improve the direct recovery of DNA from membrane filters for PCR detection. In this study, a mixed cellulose ester filter was adopted to allow a larger volume of beer to be filtrated. As a result of the optimization of the DNA extraction process that minimizes the loss of DNA and the effect of PCR inhibitors, 100 (1–10) cells/300 ml beer were successfully detected for beer spoilage LAB. Furthermore, a challenge test using 3,000 ml beer showed that 100 cells of Levilactobacillus (Lactobacillus) brevis were detectable without the negative effects of beer-originated PCR inhibitors, indicating that a trace level of contamination, corresponding to 1 cell in 300 ml of beer products, is detectable. It was also shown that the test was completed in approximately 8 hours. Therefore, this newly developed method is considered to be useful for the culture-independent direct detection of an extremely low level of beer spoilage LAB without a traditional culturing process. Supplemental data for this article is available online at at.

Imbibition of Newtonian Fluids in Paper-like Materials with the Infinitesimal Control Volume Method

Paper-based microfluidic devices are widely used in point-of-care testing applications. Imbibition study of paper porous media is important for fluid controlling, and then significant to the applications of paper-based microfluidic devices. Here we propose an analytical approach based on the infinitesimal control volume method to study the imbibition of Newtonian fluids in commonly used paper-like materials. Three common paper shapes (rectangular paper strips, fan-shaped and circular paper sheets) are investigated with three modeling methods (corresponding to equivalent tiny pores with circle, square and regular triangle cross section respectively). A model is derived for liquid imbibition in rectangular paper strips, and the control equations for liquid imbibition in fan-shaped and circular paper sheets are also derived. The model is verified by imbibition experiments done using the mixed cellulose ester filter paper and pure water. The relation of imbibition distance and time is similar to that of the Lucas−Washburn (L−W) model. In addition, a new porosity measurement method based on the imbibition in circular paper sheets is proposed and verified. Finally, the flow rates are investigated. This study can provide guidance for the design of different shapes of paper, and for better applications of paper-based microfluidic devices.

An Improved Ocular Impression Cytology Method: Quantitative Cell Transfer to Microscope Slides Using a Novel Polymer

ABSTRACT Purpose To develop a more efficient impression cytology (IC) method for the transfer of ocular surface cells onto glass microscope slides for cytochemical, immunocytochemical, and immunofluorescence studies. Methods Cells are lifted off the ocular surface with a mixed cellulose ester membrane and then firmly attached to a glass slide using a novel triblock copolymer comprised of collagen type I, polyethylenimine and poly-L-lysine (CPP), and crosslinking cells and glass slide by heating and cooling. The membrane is removed intact after softening it with a butanol/ethanol solution. Transfer of cells is complete in about 10–15 minutes and is ready for staining. The efficiency of our cell transfer method was compared to current methods based on poly-L-lysine and albumin paste. Results Our method ensured almost complete transfer of cells. In contrast, the transfer of rabbit conjunctiva cells onto poly-L-lysine-covered slides was 37.5 ± 6.3% lower, and onto albumin-paste covered slides 62.5 ± 5.6% lower (mean ± SD); the transfer of rabbit goblet cells was even less efficient. The new method was also more efficient for transfer of cells from human oral mucosa obtained by IC. Transferred cells were successfully stained with H&E, chemiluminescence, and immunofluorescence agents. Using our method, we stained ocular surface cells for S100A4 and ATF4, both of which play a role in the pathophysiology of dry eye disease. We obtained similar results with oral mucosal cells, suggesting the generalizability of our approach. We propose an explanation for the strong adhesion of cells to the glass slide, which is based on their interactions with the triblock copolymer. Conclusions We developed a novel approach for the efficient and rapid transfer of cells obtained by IC onto glass microscope slides using a novel copolymer. Compared to available methods, our improved approach makes IC robust and simple, and should increase its diagnostic yield and clinical applicability.

Simplified ex-vivo drug evaluation in ocular surface cells: Culture on cellulose filters of cells obtained by impression cytology

Drug development, resource- and time-intensive, extensively employs cell-based assays to assess the efficacy and safety of candidate drugs. The widely used immortalized cell lines, experimentally convenient, have limited predictive value. In contrast, ex-vivo models more faithfully reproduce diseases but are technically challenging to establish. To address this need, we developed a simplified process for ex-vivo cell culture, demonstrating its feasibility in ocular surface cells. Conjunctival cells were harvested by impression cytology and grown on mixed cellulose ester membrane filters (MCFs). Human and rabbit conjunctival cells cultured on MCFs are 100% viable at 24 h, and 43% viable at 72 h. A gene expression study evaluating 84 genes involved in ocular inflammation demonstrated that ex-vivo culturing maintains intact the expression of two thirds of these genes in human cells. That these cells are suitable for the assessment of ocular drugs was demonstrated by studying the effect of phosphosulindac (PS), a small molecule under development for the treatment of dry eye disease, in both human and rabbit conjunctival cells. PS, for example, suppressed the expression of CXCL10, a cytokine participating in the pathogenesis of dry eye disease, in human and in rabbit conjunctival cells cultured ex-vivo by 32% and 70%, respectively. Conjunctival cells cultured ex-vivo can be transfected to evaluate mechanistic questions. We successfully transfected such cells with a plasmid expressing luciferase under the control of an IFN-γ-responsive promoter or its control plasmid. IFN-γ stimulated luciferase expression by 85% in cells with the responsive plasmid but not in controls; PS significantly suppressed this induction by 37% without affecting the control plasmid. These findings demonstrate that human and rabbit conjunctival cells cultured ex-vivo with our method are viable and maintain their biological integrity; respond to biological and pharmacological agents; and are transfectable with informative plasmids. The unique advantage of this method is to potentially accelerate the development of novel drugs for the treatment of ocular surface diseases, and to advance our understanding of ocular surface pathophysiology.

Synthesis of mixed chitin esters with long fatty and bulky acyl substituents in ionic liquid

This study revealed that mixed chitin esters with long fatty and bulky acyl substituents were efficiently synthesized by acylation using acyl chlorides in the presence of pyridine and N,N-dimethyl-4-aminopyridine in an ionic liquid, 1-allyl-3-methylimidazolium bromide (AMIMBr), at 100 °C for 24 h. A stearoyl group was selected as the first substituent, which was combined with different long fatty and bulky acyl groups as the second substituents. In addition to IR analysis of the products, which suggested progress of the acylation, 1H NMR measurement was allowed for structural confirmation for high degrees of substitution (DSs) of the desired derivatives in CDCl3/CF3CO2H solvents. Crystalline structures and thermal property of the products were evaluated by powder X-ray diffraction and differential scanning calorimetry measurements, respectively. All the products showed film formability by casting from solutions in chloroform or chloroform/trifluoroacetic acid solvents. The occurrence of halogen exchange between acyl chlorides and AMIMBr in the present system was speculated to produce highly reactive acyl bromides in situ, which efficiently reacted with hydroxy groups in chitin to obtain high DS products.

Chemically induced strengthening of curdlan alkylcarbamate thermoplastics

AbstractCurdlan alkylcarbamate (CrdC) with a degree of substitution (DS) of ~2 was chemically modified via postesterification using carboxylic anhydride at a residual OH. Fully substituted mixed esters of curdlan carbamate/carboxylate (CrdCE) (DS = 3) with carbamate hydrogen bonding ability were obtained in high yields (>80%). Owing to replacing the residual OH with alkanoates, the glass transition temperature of CrdCE was lower than that of the corresponding CrdC. All the CrdCE displayed a greater deformability evaluated by elongation at break, being more remarkable when introducing longer esters (almost two times higher than the unmodified CrdC) than shorter esters (1.4 times higher). On the other hand, the effect on both Young's modulus and tensile strength depended on the length of the esters, observing an increase on both parameters when using shorter esters (19% and 17% higher, respectively), and a decrease for longer esters (33% and 6% lower, respectively). Thus, it was established that the physical properties of the thermoplastic CrdC could be controlled by modifying the residual OH with an appropriate ester group.

Oxathiaborolium-Catalyzed Enantioselective [4 + 2] Cycloaddition and Its Application in Lewis Acid Coordinated and Chiral Lewis Acid Catalyzed [4 + 2] Cycloaddition.

The nascency of second-generation sulfur-stabilized borenium cations by halophilic Lewis acid SnCl4 leads to highly active chiral Lewis acids that are very effective catalysts for [4 + 2] cycloaddition. Oxathiaborolium pentachlorostannate (5-10 mol %) successfully catalyzed cycloaddition of various dienes and dienophiles to afford cycloadducts with excellent enantioselectivity (20 examples, up to 99% ee). This super Lewis acid also exhibited good enantioselectivity for the first Lewis acid coordinated and chiral Lewis acid catalyzed [4 + 2] cycloaddition to α,β-unsaturated mixed ester amide.

Imaging and Identifying BSA Biofouling through the Combination of Fluorescence Microscopy and Flux Experiments

AbstractBiofouling decreases efficiency of membrane‐based water filtration, like desalination, because fouling decreases flow rates. Understanding biofouling mechanism is crucial for increased implementation of desalination though few techniques for studying this exist. Flux experiments are combined with fluorescent membrane images to determine the biofouling mechanism of bovine serum albumin (BSA), a common model protein, with two mixed cellulose ester membranes. Samples containing 1% to 12% fluorescently tagged BSA (remaining protein unlabeled) are tested to determine the ideal amount of labeled protein. Due to large standard deviation in the fouling decays, the relative flux decays are fit for statistical analysis. No correlation between the decay and amount of labeled protein is found, suggesting the dye has little impact on the fouling. A 2.5% or 5% labeled protein sample is optimal to generate images and visualize the beginning of cake formation (blockage of membrane pores). By fitting the flux data to biofouling mechanism equations, it is concluded BSA deposits in the membrane pores eventually leading to cake formation. These results are corroborated using scanning electron microscopy images. Combining flux and fluorescence microscopy allows for further insight into biofouling mechanism and can be applied to other biological molecules to improve filtration techniques.

Starch Formates: Synthesis and Modification.

Starch can be efficiently converted into the corresponding formates homogeneously using N-formyl imidazole obtained by the reaction of 1,1′-carbonyldiimidazole and formic acid in dimethyl sulfoxide as a solvent. Starch formates are soluble in polar aprotic solvents, not susceptible against hydrolysis, and not meltable. Thermoplastics could be generated by conversion of starch formates with long-chain fatty acids exemplified by the conversion with lauroyl chloride in N,N-dimethylacetamide, leading to mixed starch laurate formates. The mixed esters show melting temperatures mainly dependent on the amount of laurate ester moieties.