Retention behaviour of carboxylic acid methyl esters in supercritical fluid chromatography

The study on retention behavior in supercritical fluid chromatography (SFC) is necessary to understand the mechanism of the various interactions in SFC. The retention of SFC in carboxylic acid methyl ester/polymethylsiloxane/CO2 system was studied systematically and the retention behavior of this kind of compounds under various typical operation conditions was described using the method of an alternative unified theory of chromatographic retention. The results illustrated that expression: Ink.= a + b/T + cp + dp/T + ep2/T can be used to describe quantitatively the retention behavior of carboxylic acid methyl ester/polymethylsiloxane/CO2 system in the ranges of reduced density from 0.549 to 1.411. It was also found that the entropy of solute in stationary phase is dependent on the density of supercritical fluid (SF) under typical operating conditions of SFC.

Biodiesel from Palm Vegetable Oil

Energy obtained from a variety of non-renewable sources is considered unsustainable. Various fossil fuels, such as petroleum, coal, and natural gas, are among these sources. The combustion of fossil fuels resulted in the generation of greenhouse gases, which increased the amount of carbon dioxide in the atmosphere. Global warming and ozone layer degradation are the negative consequences. In a country like India, where consumable oils are still imported, it is sense to look at the possibility of using such unpalatable oils in CI engines that aren’t often utilized as cooking oil. Palm oil is a vegetable oil obtained from the monocarp of the oil palm’s crop. The main goal is to provide a low-cost, high-performance alternative to diesel. The possibility of palm oil as a realistic, modest, and effective hotspot for the generation of biodiesel is investigated in this research. The article is focused on the comparison of palm oil and diesel in terms of characteristics.

Chemical profiling of bioactive compounds in the methanolic extract of wild leaf and callus of Vitex negundo using gas chromatographymass spectrometry

BACKGROUND The investigation of plant-based therapeutic agents in medicinal plants has revealed their presence in the extracts and provides the vision to formulate novel techniques for drug therapy.Vitex negundo(V.negundo),a perennial herb belonging to the Varbanaceae family,is extensively used in conventional medication.AIM To determine the existence of therapeutic components in leaf and callus extracts from wild V.negundo plants using gas chromatography-mass spectrometry(GCMS).METHODS In this study,we conducted GC-MS on wild plant leaf extracts and correlated the presence of constituents with those in callus extracts.Various growth regulators such as 6-benzylaminopurine(BAP),2,4-dichlorophenoxyacetic acid(2,4-D),α-naphthylacetic acid(NAA),and di-phenylurea(DPU)were added to plant leaves and in-vitro callus and grown on MS medium.RESULTS The results clearly indicated that the addition of BAP(2.0 mg/L),2,4-D(0.2 mg/mL),DPU(2.0 mg/L)and 2,4-D(0.2 mg/mL)in MS medium resulted in rapid callus development.The plant profile of Vitex extracts by GC-MS analysis showed that 24,10,and 14 bioactive constituents were detected in the methanolic extract of leaf,green callus and the methanolic extract of white loose callus,respectively.CONCLUSION Octadecadienoic acid,hexadecanoic acid and methyl ester were the major constituents in the leaf and callus methanolic extract.Octadecadienoic acid was the most common constituent in all samples.The maximum concentration of octadecadienoic acid in leaves,green callus and white loose callus was 21.93%,47.79%and 40.38%,respectively.These findings demonstrate that the concentration of octadecadienoic acid doubles in-vitro compared to in-vivo.In addition to octadecadienoic acid;butyric acid,benzene,1-methoxy-4-(1-propenyl),dospan,tridecanedialdehyde,methylcyclohexenylbutanol,chlorpyrifos,n-secondary terpene diester,anflunine and other important active compounds were also detected.All these components were only available in callus formed in-vitro.This study showed that the callus contained additional botanical characteristics compared with wild plants.Due to the presence of numerous bioactive compounds,the medical use of Vitex for various diseases has been accepted and the plant is considered an important source of therapeutics for research and development.

Exploring Effective Ways of Green Printing to Reduce Harmful Volatile Organic Compounds Emissions

This paper delves into the transformative shift in the printing industry from traditional petroleum-based inks to sustainable alternatives,focusing on soy ink.Initially,it examines the environmental and health hazards associated with conventional printing,highlighting the detrimental impact of volatile organic compounds(VOCs)and toxic substances in inks.The emergence of soy ink as an eco-friendly solution is then explored.Derived from soybeans,soy ink significantly reduces the release of harmful VOCs and enhances the recyclability of printed materials.The paper discusses not only the environmental benefits of soy ink but also its operational and economic advantages,such as improved deinking capabilities and waste reduction.A notable development in soy ink technology is the use of soy methyl ester,which addresses the challenges of slow drying and penetration associated with traditional inks.The paper concludes by emphasizing the need for continued innovation in sustainable practices within the printing industry,positioning soy ink as a key player in aligning economic goals with environmental responsibility.The shift to soy-based inks exemplifies a broader trend towards sustainability,pivotal for the future health of the planet.

Crystal Structure and Anticancer Properties of Cinobufagin 3-Hemisuberate Methyl Ester

The title compound cinobufagin 3-hemisuberate methyl ester（1） was isolated from the venom of Bufo bufo gargarizans CANTOR. The crystal structure of 1, C35H48O9, was determined by single-crystal X-ray diffraction analysis. It belongs to orthorhombic, space group P212121 with a = 8.9338（3）, b = 16.2970（4）, c = 22.4019（6） , V = 3261.59（16） 3, Mr = 612.73, Z = 4, Dc = 1.248 g/cm3, μ = 0.725 mm-1, F（000） = 1320, S = 1.040, the final R = 0.0374 and wR = 0.0412 for 4458 unique reflections, of which 4088 were observed（I 〉 2σ（I））. In the solid state, short intermolecular C-H...O interactions involving a methine and the ester carbonyl group in cinobufagin moiety and a methyl in the suberate moiety linked adjacent molecules into a three-dimensional network. Detailed analysis of the 1H-NMR data showed that X-ray structure of 1 would be expected to closely resemble the solution conformation in chloroform. Compound 1 was inactive for the inhibition of PC3 and HepG2 cancer cells, but the parent compound cinobufagin showed potent inhibition with IC50 values of 0.145 and 5.48 μM, respectively, indicating that esterification at C（3） decreased the cytotoxic effect of 1.

Synthesis and Crystal Structure of 4-(4,6-dimethoxyl -pyrimidin-2-yl)-3-thiourea Carboxylic Acid Methyl Ester

The title compound 4-（4,6-dimethoxylpyrimidin-2-yl）-3-thiourea carboxylic acid methyl ester was synthesized by the reaction of 2-amino-4,6-dimethoxyl pyrimidine, potassium thiocyanate and methyl chloroformate in ethyl acetate. Single crystals suitable for X-ray measurement were obtained by recrystallization with the solvent of dimethyl formamide at the room temperature. The structure was characterized by elemental analysis and IR and determined by X-ray diffraction analysis＇ Crystallographic data： C9H12N4O4S, Mr = 272.29, monoclinic, space group C2/m with a = 1.6672（3）, b = 0.66383（12）, c = 1.1617（2） nm, β = 109.275（2）°, V = 1.2136（4） nm^3, Dc = 1.490 g/cm^3,μ = 0.281 mm^-1, F（000） = 568, Z = 4, R1 = 0.0341and wR2 = 0.1042.

Electrospray Ionization Mass Spectra of Amino Acid Methyl Ester 5′-Phosphoramidates of 2′,3′-Isopropylideneuridine

Amino acid methyl ester phosphates were synthesized and determined by using positive-ion mode dectrospmy ionization mass spectrometry（ESIMS） in combination with multistage tandem mass spectrometry. The fragmentation pathways were investigated, and it was observed that most fragment ions contained the phosphoryl group. It was interesting to observe that the fragmentation pathways of the protonated molecule show some differences when compared with those of the sodium ion adduct. The methoxy group of amino acid methyl ester can migrate from the carbonyl group to the phosphoryl group in the sodium ion adduct.

Study on the Total Synthesis of 3-Oxo-9β-Acetoxyilicic Acid─The Synthesis of 9β-Acetoxy-3(4),11(13)-Dien-5αH,7αH-12-Eudesmanoic Acid Methyl Ester

The synthesis of 99-acetoxy-3(4), 11(13)-dien-5αH 7αH-12-eudesmanoic acid methyl ester (2) was achieved from oxycarvone. The key step is the p-toluenesulfonhydrazide assisted reductiv rearrangement reaction

Chiral Separation of N-Benzoyl Phenylalanine Methyl Ester by Nonaqueous Capillary Electrophoresis

A successful chiral separation of N-benzoyl phenylalanine methyl ester has been achieved by nonaqueous capillary electrophoresis (NACE) using P-CD as chiral selector in formamide (FA). Some experimental parameters influencing the chiral separation such as concentration of P-CD, ionic strength and apparent pH (pH*) are discussed.

Kinetic Resolution of DL-Phenylalanine Methyl Ester by α-Chymotrypsin Immobilized on Porous Silica Beads

Kinetic resolution of DL-phenylalanine methyl ester was carried out using drimobilized α -chymotrypsin (IC) as catalyst. The effects of temperatUre, pH, concentration of substrate and reactionvessels on the resolution were investigated. High quality L-phenylalanine was obtained in good yieldby an IC column.

Methyl Ester Type Produced by Catalytic Transesterification:From Various Oil Feedstock to Biodiesel Products

Biodiesel research has been carried out via transesterification.However,biodiesel products(methyl esters)have not encountered new insights,because feedstocks have been explored and studied.Various optimum conditions on transesterification reaction could produce different methyl ester type with different compound.So,this review describes various oil feedstock that were to find new insights about methyl ester type.The review took the results of study that has been published with experience for 10 years.The results of the study reviewed on the transesterification method,characterization of methyl esters,and its components.The component reviewed and correlated to the literature,structure,and GC-MS analysis.The review can provide challenges for methyl ester research in future research.

Comparative Evaluation of the Thermal Aging of Solid Insulation in Mineral Oil and Methyl Ester of Palm Kernel Oil

The purpose of this work is to determine the impact of thermal aging on the dielectric and physicochemical properties of the oil/paper mixed insulation. We performed a comparative analysis of dielectric paper dipped in two cooling fluids: palm kernel oil methyl ester (MEPKO) and mineral oil (MO). Two types of dielectric paper were used: Thermally Upgraded Kraft paper (TUK) and Nomex-910 paper (NP-910). An accelerated aging test was realized at 110°C during a total of 96 hours. Samples of oil and paper were collected after 0, 48, 72 and 96 hours for analyses purposes. The analyses performed included the measurement of the Breakdown voltage (BDV) of the dielectric papers, the Total Acid Number (TAN) and the Decay Dissolved Products (DDP) of the liquid dielectrics. The BDV of NP-910 is greater than the BDV of TUK. Concerning the type of oil, the BDV of dielectric papers impregnated with MEPKO is greater than the BDV of similar papers impregnated with MO, indicating a better preservation of paper when dipped in methyl esters. The analyses of TAN and DDP revealed that Nomex-910 improves the oxidation stability of MO, but reduces the oxidation stability of MEPKO. These results prove that methyl esters can be used as a substitute to replace mineral oils in power transformers. Furthermore, they show that NP can be used mainly in areas of transformer where solid insulation is subjected to high thermal and electrical stress, and TUK other places where solid insulation is required. Such combination could assure money savings and a better preservation of the oil viscosity.

Evaluation of methyl ester sulphonate spacer fluid additive for efficient wellbore clean-up

Oil-based drilling fluid(OBDF)is used to drill through high permeable pay zone to prevent possible damage to the formation.However,the oil based drilling fluid leaves behind filter cake residue and oilwet surfaces which hinder cement bonding.Spacer fluid is usually introduced to clean up the wellbore prior to cementing job.This work presents a spacer fluid designed with environment-friendly anionic methyl ester sulphonate(MES)surfactant and evaluated through a series of experimental tests to ascertain its effectiveness to clean wellbore.Addition of methyl ester sulphonate to confected waterbased drilling fluid at high amount(0.15 g and 0.20 g)showed good rheological properties,compatibility with OBDF and cement and low contact angle on steel and sandstone in the range of 21.9°-34.7°.Furthermore,results show that it requires less amount of MES spacer fluid to revert oil-wet OBDF aqueous phase to water external continuous phase,validating the low contact angle measurements.Cleaning efficiencies for two best performing MES spacer fluids achieved 83.27%and 94.3%respectively.Shear bond strength were measured to be 1.3 MPa and 1.05 MPa for steel and sandstone respectively,above the minimum allowable shear bond strength for oil well cementing.Hence,MES spacer fluid can be used to clean up wellbores in high permeable formations and in well completion,where strong cement bonding is required.

Optimization of Injection Timing and Injection Duration of a Diesel Engine Running on Pure Biodiesel SME (Soya Methyl Ester)

This study was carried out to predict the impact of injection timing and injection duration on engine brake power and Nitrogen Oxides emissions in a diesel engine using biofuel Soya Methyl Ester (SME). Predictions were accomplished at three different injection timings 10°, 5° Crank Angle (CA) before Top Dead Center (bTDC) and 0° CA at Top Dead Center (TDC) and four injection durations 20°, 25°, 30°, 35° CA. The study was conducted using a simulation software (Diesel-RK). The predicted results showed that the powers produced by all the setups of the different injection timings are almost equal, but they differ in injection durations, e.g. the power at setup (10° CA-bTDC) duration 20° CA and 2500 rpm equal to 52 kW, at setup (5° CA-bTDC) duration 25° CA and same engine speed the power is equal to 51 kW, and at setup (0° CA-TDC) durations 30° the power is equal to 51 kW. The power in all setups are decreased as the injection duration increased, e.g. at setup 0° CA TDC durations 25°, 35°, and 40° CA and at 4000 rpm, the brake powers are equal 71, 65, and 59 kW respectively, thus the reduction percentages are 9% and 17% when compared to the 25° injection duration. The nitrogen oxides emissions decreased as the injection duration is increased, e.g. the emissions at setup (10° CA-bTDC) durations 25°, 30°, and 40° CA and at 2500 rpm are equal 852, 589, 293 ppm respectively, the reduction percentages are 30% and 72%. The variations of injection timing and injection duration have taken a weighty influence on engine performance and emissions. The results are considered as a novelty in the field of using pure biofuel Soya Methyl Ester in diesel engine according to our information.

Impact of endothelial nitric oxide synthase activation on accelerated liver regeneration in a rat ALPPS model

BACKGROUND Although the associating liver partition and portal vein ligation for staged hepatectomy(ALPPS)induces more rapid liver regeneration than portal vein embolization,the mechanism remains unclear.AIM To assess the influence of inflammatory cytokines and endothelial nitric oxide synthase(eNOS)activation on liver regeneration in ALPPS.METHODS The future liver remnant/body weight(FLR/BW)ratio,hepatocyte proliferation,inflammatory cytokine expression,and activation of the Akt-eNOS pathway were evaluated in rat ALPPS and portal vein ligation(PVL)models.Hepatocyte proliferation was assessed based on Ki-67 expression,which was confirmed using immunohistochemistry.The serum concentrations of inflammatory cytokines were measured using enzyme linked immune-solvent assays.The Akt-eNOS pathway was assessed using western blotting.To explore the role of inflammatory cytokines and NO,Kupffer cell inhibitor gadolinium chloride(GdCl3),NOS inhibitor N-nitro-arginine methyl ester(L-NAME),and NO enhancer molsidomine were administered intraperitoneally.RESULTS The ALPPS group showed significant FLR regeneration(FLR/BW:1.60%±0.08%,P<0.05)compared with that observed in the PVL group(1.33%±0.11%)48 h after surgery.In the ALPPS group,serum interleukin-6 expression was suppressed using GdCl3 to the same extent as that in the PVL group.However,the FLR/BW ratio and Ki-67 labeling index were significantly higher in the ALPPS group administered GdCl3(1.72%±0.19%,P<0.05;22.25%±1.30%,P<0.05)than in the PVL group(1.33%±0.11%and 12.78%±1.55%,respectively).Phospho-Akt Ser473 and phospho-eNOS Ser1177 levels were enhanced in the ALPPS group compared with those in the PVL group.There was no difference between the ALPPS group treated with L-NAME and the PVL group in the FLR/BW ratio and Ki-67 labeling index.In the PVL group treated with molsidomine,the FLR/BW ratio and Ki-67 labeling index increased to the same level as in the ALPPS group.CONCLUSION Early induction of inflammatory cytokines may not be pivotal for accelerated FLR regeneration after ALPPS,whereas Akt-eNOS pathway activation may contribute to accelerated regeneration of the FLR.

Detailed investigation of optimized alkali catalyzed transesterification of Jatropha oil for biodiesel production

The non-edible oils are believed to be one of the major feedstock for the production of biodiesel in future.In the present study,we investigated the production of Jatropha oil methyl esters（JOMEs） via alkali-catalyzed transesterification route.The biophysical characteristics of Jatropha oil were found within the optimal range in accordance with ASTM standards as a substitute diesel fuel.The chemical composition and production yield of as-synthesized biodiesel were confirmed by various analytical techniques such as FT-IR,1H NMR,13 C NMR and gas chromatography coupled with mass spectrometry.A high percentage conversion,～96.09%,of fatty acids into esters was achieved under optimized transesterification conditions with 6 ：1 oil to methanol ratio and 0.9 wt% Na OH for 50 min at ～60°C.Moreover,twelve fatty acids methyl esters（FAME） were quantified in the GC/MS analysis and it was interesting to note that the mass fragmentation pattern of saturated,monounsaturated and diunsaturated FAME was comparable with the literature reported values.

Lipid Distribution in Marine Sediments from the Northern South China Sea and Association with Gas Hydrate

The distributions of lipids in surface and subsurface sediments from the northern South China Sea were determined. The n-alkanes were in bimodal distribution that is characterized by a centre at n-C16 –n-C20 with maximum at C18（or C19） and n-C27 –n-C31 as well as at C29（or C31）. The short-chain alkanes suffered from significant losses due to their slow deposition in the water column, and their presence with a slight even carbon predominance in shallow seafloor sediments was ascribed mainly to the direct input from the benthos. The long-chain alkanes with odd predominance indicate transportion of terrigenous organic matter. Immature hopanoid biomarkers reflect the intense microbial activity for bacteria–derived organic matter and the gradual increase of maturity with burial depth. Abundant n-fatty acid methyl esters（n-FAMEs） that are in distributions coincident with fatty acids were detected in all samples. We proposed that the observed FAMEs originated from the methyl esterification of fatty acids; methanol production by methanotrophs and methanogenic archaea related to the anaerobic oxidation of methane, and sulfate reduction provided an O–methyl donor for methylation of fatty acids. The CH4 released from hydrate dissociation at oxygen isotope stage II of Cores ZD3 and ZS5, which had been confirmed by the occurrence of negative δ13C excursion and spherical pyrite aggregates, could have accelerated the above process and thus maximized the relative content of FAMEs at ZD3-2（400–420 cm depth） and ZS5-2（241–291 cm depth）.

Effect of natural and synthetic antioxidants on oxidative stability of FAMEs obtained from hevea brasiliensis

Biodiesel(fatty acid alkyl esters),an alternate to fossil fuel,has the tendency of autoxidation and hence requires antioxidants for long term storage.The influence of synthetic and natural antioxidants on the oxidative stability was analysed for fresh FAMEs(fatty acid methyl esters)obtained from hevea brasiliensis at 140 C.Higher activity was observed for synthetic antioxidants following the order of GA】BHT】DTBP】Q】GT-M】PH-M】GT-C,whereas the oxidative stability of stored FAMEs samples measured at 110 C reveals a nearly inverse trend.Storage stability was tested for the FAMEs obtained from hevea brasiliensis stored at 30 C,after addition of synthetic and natural antioxidants—butylated hydroxytoluene(BHT),2,6-di-tert-butylphenol(DTBP),quercetin(Q),gallic acid(GA),methanol extracts from green tea(GTM),pomegranate hull(PH-M),and chloroform extract of green tea(GT-C).Antioxidant activities above 1500 ppm was in the order of DTBP】BHT】GA】GT-C】GT-M】Q】PH-M.Synthetic antioxidants have been found more efficient to improve the storage stability of FAMEs obtained from hevea brasiliensis.DTBP in particular has the highest protection factor.

Determination of the Fatty Acid Profile of Breast Milk from Nursing Mothers in Bungoma County, Kenya

The fatty acid profile in breast milk of nursing mothers who participated in a Cohort for Vitamin A (COVA) study at the fourth and ninth month of lactation was investigated. Breast milk samples were collected by manual expression and stored at - 20°C until analysis. The fat was extracted from the milk and methylated using the American Oil Chemists’ Society (AOCS) Official Methods with modifications. The separation, identification and quantification of the fatty acid methyl esters was performed by gas chromatography coupled with mass spectrometry (GC-MS). Fat contents of human milk increased significantly between the fourth and ninth month of lactation 0.38 and 1.21 mg·mL-1 respectively;P 0.05) than the average percent of the total unsaturated FAs (48.93%). Similarly, at the 9th month the percentage average of the total saturated fatty acids (15.18%) was significantly lower (P < 0.05) than the average percent of the total unsaturated FAs (31.05%). The results obtained in this study demonstrated that the fat content in breast milk significantly increased in the 9th compared to the 4th month of lactation. The fatty profile was also significantly different with the omega 6 being the dominant at the 9th month compared with the omega - 9 being dominant at the 4th month of lactation.

A simple and efficient synthesis of the valsartan

Valsartan 1, one of the most important agents used in antihypertensive therapy today, was synthesized starting from L-valin methyl ester hydrochloride 2 through four steps in an overall yield of 60%. The key step involves the palladium-catalyzed Suzuki coupling. This method overcomes many of the drawbacks associated with the previously reported syntheses and is more suitable for industrial production.