Average Relative Molecular Mass Research Articles

Isolation, purification, and structural elucidation of Stropharia rugosoannulata polysaccharides with hypolipidemic effect.

Stropharia rugosoannulata is a widely grown edible mushroom with a high nutritional value. S. rugosoannulata polysaccharides is one of the most important bioactive components of S. rugosoannulata and has a wide range of activities. A S. rugosoannulata polysaccharides, named SRF-3, was derived from the S. rugosoannulata extraction by freeze-thaw combine with hot water extraction method, then prepareed with DEAE-cellulose column and Sephacryl S-200 HR gel column, and its hypolipidemic activity was determined. The structural characteristics of SRF-3 were analyzed by infrared spectral scanning (FT-IR), ultra-high performance liquid chromatography (UHPLC), acid hydrolysis, methylation analysis, nuclear magnetic resonance (NMR), and Gas Chromatography-Mass Spectrometer (GC-MS). SRF-3 is composed of mannose, galactose, methyl galactose and fructose with ratios of 16, 12, 58 and 12, respectively. In addition, the average relative molecular mass of SRF-3 is approximately 24 kDa. The main chain of SRF-3 is mainly composed of repeating α-D-1,6-Galp and α-D-1,6-Me-Galp units, with branches in the O-2 position of Gal. The structure is presumed to be a mannogalactan, with a small amount of t-β-D-Manp present as a side chain. Hypolipidemic activity assay showed that SRF-3 had good antioxidant and hypolipidemic effects in vitro, suggesting that SRF-3 have potential application in reducing liver fat accumulation.

Efficient and rapid electrocatalytic degradation of polyethylene glycol by ammonium jarosite

Polyethylene glycol (PEG) in an aqueous environment is a potential problem for water pollution treatment because of its high thermal stability, difficult hydrolysis, and high biocompatibility. This study achieved the efficient and rapid degradation of PEG with a high polymerization degree of PEG (Mn = 20,000 g/mol) in simulated wastewater by a heterogeneous electro-Fenton process using ammonium jarosite as a catalyst. The results showed that the COD removal rate of simulated wastewater and the removal rate of PEG reached 85.85% and 92.29% within 60 min, respectively, and the number average molecular weight (Mn) of PEG was reduced by 79.18% at 180 min under the conditions of 80 mg/L PEG, pH = 3, current density of 5 mA/cm2, ammonium jarosite dosing amount of 0.8 g/L and aeration rate of 1 L/min. The catalytic mechanism of ammonium jarosite was proved that highly oxidative hydroxyl radicals (·OH) in the heterogeneous electro-Fenton process were the most critical active species, which can efficiently and rapidly oxidize PEG molecules. The oxygen atom in the ether bond of PEG molecules has lone pairs of electrons, which interact with the hydroxyl groups on the surface of ammonium jarosite to weaken the ether bonds in the PEG molecules. Then the ether bond is easily to be broken under the attack of the hydroxyl radical. The breakage of the polymer chains during PEG degradation leads to a continuous decrease in the average relative molecular mass of PEG, accompanied by the formation of aldehyde and carboxylic acid intermediates, which are eventually oxidized to form CO2 and H2O as the degradation time increases.

Particle Size Effect on the Water Vapour – Activated Tamarind Seeds (Tamarindus indica L.) Toward the Adsorbent Physical Properties

The increasing problem of dyestuff liquid waste in the textile industry occurs due to the low adsorption of textiles toward dyes. Therefore, various efforts have been made to enhance the fabric’s absorption. One method that has been done is by adding biomass-derived dye-binding additives which act as an adsorbent. One of potential biomasses is tamarind seeds. The purpose of this study is to determine the effect of particle size of tamarind seeds, which is physically activated, on the adsorbent character. The variation of adsorbent particle size applied were -80 + 100 mesh (177-149 μm), -100 + 120 mesh (149- 125 µm), -120 + 150 mesh (125-99.3 µm) and less than 150 mesh (<99.3 µm). Tamarind seed was activated using water vapour at high pressure prior to the application. The adsorbent characters were studied based on particle size distribution, powder porosity, average relative molecular mass, and hydrophilicity. In addition, tamarind seed chemical structure was analysed using Fourier Transform Infra-Red (FTIR) spectrophotometry, while adsorbent potency was studied in the form of an adsorbent thin film. The results showed that based on the analysis of particle size distribution, adsorbents with the best activation results was obtained by particle size of 125-149 μm. The highest porosity was achieved by particle that smaller than 99.3 µm and the highest average relative molecular mass, based on the Mark–Houwink approach, was obtained by particle size of 125-149 µm. The highest hydrophilicity, which was determined based on the contact angle, was obtained by particle sizes of 99.3-125 µm.

Terpolymerizations of CO2, Propylene Oxide and DL‐Lactide Catalyzed by Zn‐Fe DMC Catalysts with Quaternary Ammonium Salts

AbstractPolymers synthesized from carbon dioxide (CO2) and epoxy compounds are biodegradable materials and therefore are potentially very important in tackling the plastic pollutions. In this work, we synthesized Zn–Fe DMC catalysts with quaternary ammonium salts as a cocatalyst via ball milling. The obtained catalysts showed excellent activity (turn over frequency up to TOF=5.65 g‐polymer/g‐Zn h−1) in the terpolymerizations of CO2, propylene oxide and DL‐Lactide, yielding the biodegradable polymers with average relative molecular mass between 9.8×103 and 1.1×104, and the polydispersity index in the range of 1.7‐2.0. The main advantages of using mechanochemical method for the synthesis of the catalysts lie in the easy adjustment of co‐catalyst loading and its operational simplicity.

Separation of low polarity petroleum sulfonate: Eluant selection, characterization, and theoretical calculation

ABSTRACTPetroleum sulfonate is one of the most important surfactant in tertiary oil recovery process. Among complex components, low polarity petroleum sulfonate account for about 70% of total, but the main contributing components are still unknown, and the accurate evaluation method is imperative. In this work, low polarity petroleum sulfonate was successfully separated into four parts. All the separated samples were characterized by mass spectrometry, infrared spectroscopy, and nuclear magnetic resonance. The average carbon number, average aromatic carbon number, average saturated carbon number, and the average number of methyl were obtained. The results revealed that average relative molecular mass and branched degree are the main factors of varied polarities of petroleum sulfonate. What more, this study provided a reliable evaluation and characterization method of low polarity petroleum sulfonate.

Determination of the relative molecular mass distribution of the ultrafiltration fractionation product of lignosulfonate by advanced polymer chromatography

The effects of testing conditions, such as pH and ionic strength of the mobile phase, on the relative molecular mass obtained by advanced polymer chromatography (APC) were investigated systematically. The non-size exclusion effects were discussed for lignosulfonate and its ultrafiltration fractionation product. The relative molecular mass distribution of lignosulfo-nate was well-characterized by an APC system using three columns in series, with a 10 μ L injection volume and 0.1 mol/L NaNO3 as the aqueous mobile phase, at a flow rate of 0.5 mL/min. The relative molecular mass distribution is in the eight molecular mass ranges. Optimized test conditions were used to characterize the ultrafiltration fractionation product of lignosulfonate. The obtained number average relative molecular masses (Mn) of the three components were 40410, 12208, and 1516 Da, indicating that lignosulfonate was well separated into three fractions by ultrafiltration membrane separation. The APC technique presented herein provides the basis for further application of the fractional separation products of lignosulfonate.

Relative molecular mass and monosaccharide composition of polysaccharide in Dendrobium officinale flowers

In order to provide new information on polysaccharide in Dendrobium officinale flowers,the monosaccharide composition and relative molecular mass distribution of 11 families of flowers were investigated and analyzed by high performance gel filtration chromatography (HPGFC) and pre-column derivatization ultra performance liquid chromatography (UPLC) in this study. Then cluster analysis was carried out for the monosaccharide peak areas by utilizing SPSS 19.0 software. The results showed that the polysaccharides of all the above 11 hybrid families of D. officinale flower were separated into three fractions (DOP-1, DOP-2 and DOP-3) with the average relative molecular mass of 5.53×105, 3.49×105 and 2.12×105. The polysaccharides in 11 different families were mainly composed of glucose, mannose, galactose, galacturonic acid and arabinose; mannose had the highest proportion among them, with mannose/glucose ratio of 0.302-3.335. Additionally, the relative contents of various monosaccharides in different families varied. 11 families of D. officinale flower could be classified into four categories according to their monosaccharide components and relative contents. In this study, the relative molecular mass distribution and monosaccharide composition of polysaccharides in D. officinale flowers were defined, which can provide foundations for its resource utilization．.

Quenching of reactive intermediates during mechanochemical depolymerization of lignin

Mechanochemical reactions are performed to depolymerize organosolv lignin with sodium hydroxide in a mixer ball mill. GPC analysis reveals that rapid depolymerization into small oligomers occurs within minutes of milling time, followed by a slower reduction in average relative molecular mass over the next 8h of milling. Monomeric products are identified by GC–MS and quantified by GC-FID. The extent of depolymerization appears to be limited by repolymerization reactions that form bonds between products. Suppression of these repolymerization reactions can be achieved through the addition of methanol as a scavenger or adjustment of the moisture content of the feedstock. These modifications result in lower average relative molecular masses and higher yields of monomers. These results are an important step towards designing an efficient pathway for lignin valorization.

Self-Association of Apo A-1 Studied with Dynamic and Static Light Scattering.

Static and dynamic light scattering were employed to determine simultaneously the average relative molecular mass, Mr, and the average hydrodynamic radius, Rh, of protein molecules. The new method was applied to the association-dissociation equilibrium of apolipoprotein A-1 (Apo A-1) and its thermal unfolding. As a control, lysozyme was measured as a nonassociating protein. Apo A-1 forms oligomers as a function of concentration and temperature, and the equilibrium can be described by a cooperative association model, consisting of a nucleation step and a growth step. At concentrations of 1 and 2.7 mg/mL, the Apo A-1 solution contained mainly monomers and octamers, with intermediates occurring at very low concentrations. Oligomer formation was maximal at 22 °C and was characterized by a temperature-dependent association constant. The cooperative association model allows the quantitative analysis of both the average relative molecular mass, Mr, and the average hydrodynamic radius, Rh, with the same set of model parameters which, in turn, are also applicable to analytical ultracentrifugation experiments. The light scattering experiments were reversible as long as the Apo A-1 solution was not heated above 60 °C.

Thermal Stability and Crystallinity Study of Polystyrene/SiO&amp;lt;sub&amp;gt;2&amp;lt;/sub&amp;gt; Nano-Composites Synthesis via Microwave-Assisted &amp;lt;i&amp;gt;In Situ&amp;lt;/i&amp;gt; Polymerization

Serials of polystyrene/SiO2 Nano composites (PS/SiO2) with different content of inorganic fillers were successfully prepared by the in situ bulk radical polymerization of styrene under microwave irradiation. The effect of the amount of Nano SiO2 on the properties of the PS/SiO2 Nanocomposites along with the average relative molecular masses (Mn, Mz and Mw) was investigated by thermal analysis and X-Ray Diffraction (XRD). Their structural model was proposed on the basis of the Optical Microscopy, FTIR (Fourier Transform Infrared) analysis, differential scanning calorimetry (DSC), gel permeation chromatography (GPC) and X-Ray Diffraction (XRD). The dispersion of nanoparticles in Polystyrene is observed in the magnified image. The effect of microwave irradiation power on molecular weight of polystyrene was also studied. It was found that, the microwave assisted reaction needs less time as compare to conventional polymerization and found to be in between 10 to 15 min.

Relative molecular mass determination of phenolated depolymerized sodium lignosulfonate by advanced polymer chromatography system

Advanced polymer chromatography (APC) is a newly developed high resolution polymer characterization technique. Within 10 min, it can separate polymers with high resolution and obtain the average relative molecular mass distribution parameters of the polymers. The Mr distribution of the depolymerized lignin product was well characterized with low relative standard deviation (RSD less than 1%) by APC system using ACQUITY AQ 450 Å, 200 Å, and 45 Å columns in series, with 10 µL injection volume, and weak alkaline phosphate buffer solution as the aqueous mobile phase at a flow rate of 0.5 mL/min. Compared with traditional gel permeation chromatography (GPC), the APC system had the advantages of high sensitivity and good reproducibility. The technique to determine the average relative molecular mass distribution of depolymerized lignin oligomers in aqueous phase described in this paper will pave the way for new methods to separate and analyze high performance natural materials, and the feasible method for the investigation of the mechanism of depolymerization and the regulation for liquefied lignin would also be established.

Preparation and Performance of Phosphated Waterborne Polyurethane/Nanosilica

A phosphated polyester polyol with a 1500 number average relative molecular mass was synthesized by 2-phosphono-1,2,4-butanetricarboxylic acid and 2,2-dimethyl-1,3-propane diol. Then the polyester polyol was reacted with isophorone diisocyanate to obtain the prepolymer. The prepolymer was extended by 1,4-butanediol and terminated by coupling agent KH550. At last nanosilica was added into the waterborne polyurethane( WPU) to obtain WPU /nanosilica composite. Fourier transform-infrared spectroscopy( FT-IR),thermal gravimetric analysis( TGA) and transmission electron microscopy( TEM) were used to study the structure and characteristics of the composite. In the TEM image of PWPU /SiO2,plenty of composite particles( ~110 nm diameter) were observed. Combined analysis with the FI-IR,it was concluded that the nanosilica was linked with WPU by chemical bond. TGA,char yield and extension test showed that the fire retardancy property, thermostability and tensile strength of the composite increase significantly with tnanosilica modification. These results indicate that there is a good application prospect of the composite in the future.

Laboratory Experiment Research and Field Tests on Catalyst of Aquathermolysis of Heavy Oils

Aquathermolysis reaction of heavy oils occurring in high temperature water environment significantly degrades the heavy components of heavy oils, improves oil quality and reduces its viscosity. Aerosol, oil-soluble, and water-soluble nickel catalysts obviously and effectively catalyze the aquathermolysis reaction of heavy oils in a high temperature and reduces its viscosity, producing a gas increase of 49%, 41% and 21% respectively compared with the result with the absence of any catalyst. An aerosol, oil-soluble and water-soluble nickel catalyst compound (best quality ratio 1:1:2) increases the oil recovery of heavy oils by 8.5% and decreases the viscosity of sample oil and average relative molecular mass of porous media by 89.6% and 23% respectively, with its resin and asphaltene content significantly reduced. The pilot field tests show that, the test cycle production of heavy oils of each well proves an increase of 81.2 ~ 226.1t (not considering the cycle decline rate) over the previous one, which means that the field tests coincide with the laboratory experiments.

Catalytic synthesis of perfluorolyethers

Perfluorolyether is characterized by highly chemical inertness, oxidative stability, anticorrosion as well as radiation resistance. It can be used as lubricant especially in harsh environmental conditions. In this work, hexafluoropylene oxide was catalytically polymerized at low temperature using the methods of anionic polymerization, and perfluorolyethers were obtained with number-average degree of polymerization more than 15. CsF and RbF were used as catalysts and their catalytic activities were investigated. Experimental results show that perfluorolyethers with number-average molar masses up to 3 000 g/mol could be obtained using the two kinds of catalysts, respectively. As compared to CsF, the number-average degree of polymerization is higher and the relative molecular mass distribution interval is narrower when RbF is used as catalyst. The effect of factors such as impurities’ content, reaction temperature and reaction time on the number-average degree of polymerization was also investigated. It is found that low impurities’ content and low temperature are beneficial to the generation of high number-average degree of perfluorolyethers. The optimization reaction time is 24 h, and further increase of reaction time does not significantly affect the average relative molecular mass. The product was characterized by IR, 19F NMR and GC-MS, and the catalytic mechanism was analyzed finally.

Kinetic Studies of Isophorone Diisocyanate-Polyether Polymerization with in situ FT-IR

Isophorone diisocyanate is used to react with poly (propylene oxide) of 1000 number average relative molecular mass in different temperatures. In situ FT-IR is used to monitor the reaction to work out rate constant, Arrhenius equation, and Eyring equation. The polymerization reaction has been found to be a second-order reaction, and rate constant seems different between the first stage and second stage at 5°∼10°C. However, it is surprising that the reactivity difference disappeared and the reaction rate merges when reaction temperature increases. The 1/(1 − p)∼t curves become straight at 15°∼25°C. Finally, the activation energy (E a), activation enthalpy (ΔH), and activation entropy (ΔS) for the polymerization are calculated, which are 73.9 KJ · mol−1, 71.6 KJ · mol−1, and −21.0 J · mol−1 · k−1, respectively.

Synthesis of Poly-L-Lactide for Scaffold Materials by Melt-Solid Polycondensation

Poly-L-lactide (PLLA) with low viscosity average molecular mass for scaffold materials was synthesized by melt-solid condensation polymerization and characterized by IR, XRD, and 1H-NMR. The influences of catalyst (LaCl3/C7H8SO3) concentration, polymerization temperature and polymerization time on the viscosity average molecular mass of poly-L-lactide acid (PLLA) were investigated. Poly-L-lactide with a viscosity average relative molecular mass of about 7.2 × 104 was obtained when melt-solid polycondensation was conducted with first preheating at 110°C for 4 h and solid polycondensation at 150°C for 20 h; the catalyst concentration was 0.4 wt. %. PLLA was made into porous materials by using sodium hydrogen carbonate particulates as the porogen to foam. Scanning electron microscope observation indicates that the sample is highly porous and well distributed with good interconnections between pores and the pore size of porous materials in the range of 300–500 μm and it can be used as scaffold for bone tissue engineering.

A novel method for evaluating and improving the 1H-MRSI glioma data quality

ABSTRACT A suitable correlation can be made to represent the simulated distillation of heavy oils starting from thennoaravimetric measurements. This method is applicable to hydrocarbons having an initial boiling point equal or greater than 200°C. The simulated thermogravimetric distillation fit was obtained from experiments with the standard compounds obtained from ASTM D-2887-83 (Boiling range distribution of petroleum fractions by gas chromatography). This method is simple, fast and without problems when applied to heavy feedstocks The data were used in the determination of average boiling temperatures of products from thermal cracking and thermal hydrocracking. It was also possible to quantify coke yields Average relative molecular masses of products from the above processes correlated well with the average boiling point temperatures. It indicates that, with respect to the hydrocarbon types, thermal cracking is not selective in comparison with thermal hydrocracking The equation applied to find the average boiling temperature is following: T = (1/al) (Ttg-a2). T is the boiling temperature, al and a2 are the correction factors, Ttg is the thermogravimetric temperature.

Comparative studies on zooplankton community between the sea surface microlayer and the subsurface microlayer in Daya Bay, China

ABSTRACT A suitable correlation can be made to represent the simulated distillation of heavy oils starting from thennoaravimetric measurements. This method is applicable to hydrocarbons having an initial boiling point equal or greater than 200°C. The simulated thermogravimetric distillation fit was obtained from experiments with the standard compounds obtained from ASTM D-2887-83 (Boiling range distribution of petroleum fractions by gas chromatography). This method is simple, fast and without problems when applied to heavy feedstocks The data were used in the determination of average boiling temperatures of products from thermal cracking and thermal hydrocracking. It was also possible to quantify coke yields Average relative molecular masses of products from the above processes correlated well with the average boiling point temperatures. It indicates that, with respect to the hydrocarbon types, thermal cracking is not selective in comparison with thermal hydrocracking The equation applied to find the average boiling temperature is following: T = (1/al) (Ttg-a2). T is the boiling temperature, al and a2 are the correction factors, Ttg is the thermogravimetric temperature.

Improvement of different source function expressions in SWAN model for the Bohai Sea

ABSTRACT A suitable correlation can be made to represent the simulated distillation of heavy oils starting from thennoaravimetric measurements. This method is applicable to hydrocarbons having an initial boiling point equal or greater than 200°C. The simulated thermogravimetric distillation fit was obtained from experiments with the standard compounds obtained from ASTM D-2887-83 (Boiling range distribution of petroleum fractions by gas chromatography). This method is simple, fast and without problems when applied to heavy feedstocks The data were used in the determination of average boiling temperatures of products from thermal cracking and thermal hydrocracking. It was also possible to quantify coke yields Average relative molecular masses of products from the above processes correlated well with the average boiling point temperatures. It indicates that, with respect to the hydrocarbon types, thermal cracking is not selective in comparison with thermal hydrocracking The equation applied to find the average boiling temperature is following: T = (1/al) (Ttg-a2). T is the boiling temperature, al and a2 are the correction factors, Ttg is the thermogravimetric temperature.

Genetic analysis of segregation distortion of mating-type factors in Lentinula edodes

ABSTRACT A suitable correlation can be made to represent the simulated distillation of heavy oils starting from thennoaravimetric measurements. This method is applicable to hydrocarbons having an initial boiling point equal or greater than 200°C. The simulated thermogravimetric distillation fit was obtained from experiments with the standard compounds obtained from ASTM D-2887-83 (Boiling range distribution of petroleum fractions by gas chromatography). This method is simple, fast and without problems when applied to heavy feedstocks The data were used in the determination of average boiling temperatures of products from thermal cracking and thermal hydrocracking. It was also possible to quantify coke yields Average relative molecular masses of products from the above processes correlated well with the average boiling point temperatures. It indicates that, with respect to the hydrocarbon types, thermal cracking is not selective in comparison with thermal hydrocracking The equation applied to find the average boiling temperature is following: T = (1/al) (Ttg-a2). T is the boiling temperature, al and a2 are the correction factors, Ttg is the thermogravimetric temperature.