Sulfuric Acid Groups Research Articles

Effect of surface treatment and resin cement type on the bond strength of polyetheretherketone to lithium disilicate ceramic

BackgroundThis study aims to evaluate the effect of surface treatment and resin cement on the shear bond strength (SBS) and mode of failure of polyetheretherketone (PEEK) to lithium disilicate ceramic (LDC). This is suggested to study alternative veneering of PEEK frameworks with a ceramic material.Methodseighty discs were prepared from PEEK blank and from lithium disilicate ceramic. Samples were divided into four groups according to surface treatment: Group (A) air abraded with 110 μm Al2O3, Group (AP) air abrasion and primer application, Group (S) 98% sulfuric acid etching for 60 s, Group (SP) Sulfuric acid and primer. Each group was subdivided into two subgroups based on resin cement type used for bonding LDC:1) subgroup (L) self- adhesive resin cement and 2) subgroup (B) conventional resin cement (n = 10). Thermocycling was done for all samples. The bond strength was assessed using the shear bond strength test (SBS). Failure mode analysis was done at 50X magnification with a stereomicroscope. Samples were chosen from each group for scanning electron microscope (SEM). The three-way nested ANOVA followed by Tukey’s post hoc test were used for statistical analysis of results. Comparisons of effects were done utilizing one way ANOVA and (p < 0.05).ResultsThe highest mean of shear bond strength values was demonstrated in Group of air abrasion with primer application using conventional resin cement (APB) (12.21 ± 2.14 MPa). Sulfuric acid groups showed lower shear bond strength values and the majority failed in thermocycling especially when no primer was applied. The failure mode analysis showed that the predominant failure type was adhesive failure between cement and PEEK, while the remaining was mixed failure between cement and PEEK.ConclusionThe air abrasion followed by primer application and conventional resin cement used for bonding Lithium Disilicate to PEEK achieved the best bond strength. Primer application did not have an effect when self-adhesive resin cement was used in air-abraded groups. Priming step is mandatory whenever sulfuric acid etching surface treatment is utilized for PEEK.

Structure characterization and cryoprotective activity of an exopolysaccharide from Pseudoalteromonas sp. LP6-12-2

Non-toxic natural antifreeze agents are urgently needed in many fields. Exopolysaccharides produced by psychrophilic bacteria from harsh habitats, such as Antarctica, to battle cold environments are a significant source of biological antifreeze agents. In this study, a homogeneous exopolysaccharide (EPS0-1) was extracted from Antarctica Pseudoalteromonas sp. LP6-12-2. Using High-performance gel permeation chromatography and High-efficiency anion chromatogram, respectively, the homogeneity, molecular weight, and monosaccharide composition of EPS0-1 were examined. EPS0-1 with a molecular weight (Mw) of 4351.31 kDa was an α-configuration polysaccharide containing uronic acid, amino and sulfuric acid groups, and composed of galactosamine hydrochloride, rhamnose, glucosamine hydrochloride, galactose, glucose, mannose, galacturonic acid, and glucuronic acid with rates of 1.40:9.40:4.90:32.0:37.2:6.50:4.10:4.40, respectively. Congo red test and I2-KI reaction found that the triple helix structure of EPS0-1 polysaccharide chain was weakly bound internally, with a longer side chain and/or more branches. The smooth and dense surface of EPS0-1 under Atomic force microscopy and Scanning electron microscopy revealed that it was large polysaccharide particles. Freeze-thaw cycle and freezing point determination experiment showed that EPS0-1 may significantly increase E. Coli's freezing resistance and decrease the solution's freezing point, respectively. EPS0-1 was capable of increasing the viscosity of the solution and displaying a high degree of thermal stability, which was proved by the rheological properties. And it was not hazardous to human normal liver cell line (LO2) in a specific concentration range. Therefore, the findings of this investigation established the basis for EPS0-1 as a potential antifreeze and food functional component.

Optimization of preparation conditions, molecular structure analysis and antitumor activity of sulfated sodium alginate oligosaccharides

Sodium alginate is a kind of marine polysaccharide extracted from brown algae, and its degradation products have been widely used in food, medicine and other fields. Sodium alginate oligosaccharide (AOS) was degraded by hydrogen peroxide from sodium alginate and modified by sulfonic acid-chlorosulfonic acid-pyridine to obtain sulfated alginate oligosaccharide (S-AOS). The main research contents included the optimization of the preparation process of S-AOS and the study of its structure characterization and biological activity. First, the optimal reaction conditions of S-AOS were optimized by single factor analysis and response surface analysis. The sulfated derivatives were characterized using Fourier transform infrared spectrum (FTIR), High performance liquid chromatography (HPLC), Nuclear magnetic resonance Hydrogen (1H NMR) spectrum and Electrospray ionization mass spectrometry, and molecular formula and substitutions were determined. Molecular docking, GO and KEGG enrichment analysis were used to predict S-AOS biological activity and possible action targets, and the mechanism of tumor suppression activity of S-AOS was preliminarily investigated. The results showed that, the optimal reaction conditions for S-AOS was finally determined as: Chlorosulfonic acid - pyridine volume ratio was 7:1. Sulfation reagent – AOS volume ratio was 3:1. Reaction time was 3 h. Reaction temperature Was 40 ℃. Under this condition. In contrast to AOS, S-AOS showed two new absorption peaks in the FTIR spectrum and two new chemical shift peaks in the 1H NMR spectrum, suggesting that the sulfate group selectively reacts with the hydroxyl groups on the third carbon and the fourth on the mannoconide. The relative molecular mass of S-AOS was 1566 g/mol and a degree of sulfate substitution was 0.931. Molecular docking screening, GO and KEGG enrichment analysis of S-AOS revealed that it may have a role in apoptosis, oxidative stress, thrombosis, and cellular autophagy. In vitro experiments showed that S-AOS could inhibit the expression of apoptosis and proliferation related proteins, and showed certain anti-tumor activity. S-AOS had more or stronger biological activity by introducing sulfuric acid groups, and its application in the field of biomedicine is expanded.

Surface treatments for polyetheretherketone (Peek): Effects on the bond strength to a resin cement and on the fatigue performance of a bonded glass-ceramic

ObjectiveTo evaluate the effect of distinct surface treatments on Peek (polyetheretherketone) adhesion to the resin cement and the mechanical fatigue behavior of lithium disilicate adhesively bonded to it. Materials and methodsPeek slices embedded in plastic rings with self-curing acrylic resin were randomized into 4 groups for adhesion testing, considering the following surface treatment factors: Ctrl (just cleaned with 78 % isopropyl alcohol); Grinding (4219F diamond bur - 46 μm grain size); Air abrasion (45 μm aluminum oxide for 10 s); Sulfuric acid (acid etching for 30 s). All slices received a layer of adhesive agent; resin composite cylinder specimens (Ø = 3 mm; h = 3 mm) were produced and bonded onto the Peek slices using a dual resin cement for the shear bond strength tests (n = 20) through the wire-loop technique. Next, disc-shaped specimens of Peek (Ø = 10 mm; thickness: 2 mm) and lithium disilicate (LD) (Ø = 10 mm; thickness: 1 mm) were produced for the fatigue tests (n = 20) and paired. The LD was treated (5 % hydrofluoric acid for 20 s + silane agent) and adhesively bonded (with dual resin cement) onto Peek (treated with the previously mentioned surface treatments). The fatigue tests were performed with a step-stress approach (20 Hz; 10,000 cycles/step; initial load: 100 N; step-size: 50 N). Roughness, contact angle, topography and fractographic analysis were performed. The adhesive data was analyzed by one-way ANOVA and Tukey post-hoc tests, while the fatigue data were subjected to survival analysis (Kaplan Meier and Mantel-cox post hoc tests). ResultsOnly the air abrasion surface treatment was able to improve the bond strength between Peek and resin cement (p < 0.05); the Grinding and Sulfuric acid groups were similar to the Ctrl. All surface treatments promoted similar fatigue performance. ConclusionAir abrasion promoted increased bond strength between Peek and resin cement, having no detrimental effect on fatigue behavior. Overall, the mechanical behavior under fatigue of a lithium disilicate glass-ceramic was not influenced by the Peek substrate surface treatments.

Composite-veneering of polyether-ether-ketone (PEEK): evaluating the effects of different surface modification methods on surface roughness, wettability, and bond strength.

This study aimed to evaluate the effects of different surface modification methods on the surface roughness, contact angle, and bond strength of composite-veneer materials of polyether-ether-ketone (PEEK). Fifty-five specimens (n = 11) with a size of 7 × 7 × 2mm were cut out from PEEK discs. The specimens were divided into five groups with different surface treatments: no treatment (NO) (control group), sulfuric acid (SA), plasma (P), femtosecond laser (FS), and Nd-YAG laser (NY). After the surface treatments, the specimens were checked for roughness, contact angle, and bond strength of the composite-veneer material. Data were analyzed with the Welch test for roughness, contact angle, and bond strength parameters. Individual Pearson correlation tests were executed for all surface treatment groups to determine any significant correlations among roughness, contact angle, and bond strength parameters (P < .001). Roughness, contact angle, and bond strength values were affected by surface modification methods (P < .001). In comparison to the control group, NY and FS treatments increased the surface roughness and bond strength; they also provided bond strength values comparable to the SA group. When the relationship between the variables was examined, no correlation was seen between roughness, contact angle, and bond strength values for the NY, SA, and control groups (P > .05); however, significant correlations were determined between the contact angle and surface roughness values for the P and FS groups (P < .05). Femtosecond and Nd-YAG laser treatments are viable surface modification alternatives to the sulfuric acid treatment for the PEEK material.

In-vitro evaluation of immunomodulatory activity of sulphation-modified total ginsenosides derivative-3.

Ginseng has been used in biomedicine to prevent and treat decreased physical and mental capacities. Total ginsenosides (TG) from ginseng root which have antitumor and immune-enhancing properties, are the principal active components of Panax ginseng, while the sulphation-modified TG derivative-3 (SMTG-d3) was expected to enhance the anticancer activity in conventional medicinal treatments. The chlorosulphonic acid-pyridine technique, used for the sulfation modification of TG to improve their biological activity, and the infrared spectroscopic characteristics of TG and SMTG-d3 were investigated, and the effects of SMTG-d3 on immunocytes and cytokines relevant to tumor treatment were assessed. The MTT assay was used to assess the effect of TG and SMTG-d3 on the cytotoxicity and T-lymphocytic proliferation against mouse splenocytes. The LDH method was employed to evaluate NK activity induced by TG or SMTG-d3. The production levels of splenocytes-secreted IL-2 and IFN-γ and peritoneal macrophages-secreted TNF-α were determined using mouse ELISA kits. It showed that the ideal conditions for the sulfation modification of TG: the volume ratio of chlorosulfonic acid to pyridine lower than 1:2.5; controlled amount of chlorosulfonic acid; and a yield of 51.5% SMTG-d3 (2 h, < 45°C). SMTG-d3 showed two characteristic absorption peaks at 1,230 cm-1 and 810 cm-1, indicating the formation of sulfuric acid esters and the presence of sulfuric acid groups. SMTG-d3 exhibited higher antitumor immunological activity than TG by promoting the proliferation of T lymphocytes and the production of IFN-γ and TNF-α, thus enhancing NK cell activity, and reducing cytotoxicity. The findings imply sulfated modification represents an effective method of enhancing the immunomodulatory activities of TG and could be used as the basis for developing new drug target compounds; SMTG-d3 can serve as an antitumor immunomodulator and can be considered an effective and prospective herbal formulation in clinical applications.

Sulfonated Starch-Graft-Polyaniline@Graphene Electrically Conductive Nanocomposite: Application for Tyrosinase Immobilization

The interaction of tyrosinase with sulfonated starch-graft-polyaniline@graphene (SSt-g-PANI@G) nanocomposite was investigated by electrochemical methods. The activity of the immobilized tyrosinase (Tyase) was proved by the electrochemical detection of three substrates (L-dopa, caffeic acid, and catechol). The SSt-g-PANI@G nanocomposite was characterized by Fourier-transform infrared spectra (FT-IR), X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy-dispersive X-ray analysis (EDX), and thermogravimetric analysis (TGA). To immobilize tyrosinase on the surface of the nanocomposite, a simple drop-casting technique was used. The presence of sulfuric acid and hydroxyl groups in SSt, amine groups in PANI, and high surface-to-volume ratio and electrical conductivity of graphene in the prepared nanocomposite led to good enzyme immobilization on the electrode surface. The modified electrode showed a suitable catalytic effect on the electrochemical redox agent, compared with the bare electrode. The peak current responses for three substrates were studied with a calibration curve derived using cyclic voltammetry (CV) and differential pulse voltammetry (DPV). In addition, the fabricated SSt-g-PANI@G/Tyase/GCE showed a more suitable response to catechol, L-dopa, and caffeic acid substrates, respectively.

Fabrication and Characterization of Chicken- and Bovine-Derived Chondroitin Sulfate/Sodium Alginate Hybrid Hydrogels.

The physicochemical properties and microstructure of hybrid hydrogels prepared using sodium alginate (SA) and chondroitin sulfate (CS) extracted from two animal sources were investigated. SA-based hybrid hydrogels were prepared by mixing chicken- and bovine-derived CS (CCS and BCS, respectively) with SA at 1/3 and 2/3 (w/w) ratios. The results indicated that the evaporation water loss rate of the hybrid hydrogels increased significantly upon the addition of CS, whereas CCS/SA (2/3) easily absorbed moisture from the environment. The thermal stability of the BCS/SA (1/3) hybrid hydrogel was higher than that of CCS/SA (1/3) hybrid hydrogel, whereas the hardness and adhesiveness of the CCS/SA (1/3) hybrid hydrogel were lower and higher, respectively, than those of the BCS/SA (1/3) hybrid hydrogel. Low-field nuclear magnetic resonance experiments demonstrated that the immobilized water content of the CCS/SA (1/3) hybrid hydrogel was higher than that of the BCS/SA (1/3) hybrid hydrogel. FTIR showed that S=O characteristic absorption peak intensity of BCS/SA (2/3) was obviously higher, suggesting that BCS possessed more sulfuric acid groups than CCS. SEM showed that the hybrid hydrogels containing CCS have more compact porous microstructure and better interfacial compatibility compared to BCS.

Functionalized two-dimensional g-C3N4 nanosheets in PIM-1 mixed matrix membranes for gas separation

The virtuous of two-dimensional (2D) nanomaterials in high aspect ratio and tunable surface functionality have geared towards their implementation in mixed matrix membranes (MMMs) for advanced gas separation. In this study, the effects of functionalized 2D nanosheets in the MMMs for gas separation were investigated. The graphitic carbon nitride (g-C3N4) nanosheets were modified with various functional groups namely sulfuric acid group, aliphatic amino group, aromatic amino group, and sulfonic group via four different synthesis approaches. Polymers of intrinsic microporosity (PIMs, e.g., PIM-1) was selected as the continuous polymer phase due to its intrinsic high permeability and comparable selectivity towards different gas pair. The sulfonic acid functionalized g-C3N4 MMMs (e.g., PIM-1/g-C3N4-D) imparted high separation properties ascribed to the great CO2 affinity induced by the sulfonic acid groups. In particular, PIM-1/g-C3N4-D (99:1) MMM demonstrated promising CO2 separation performance, with CO2 permeability of 3740 Barrer and CO2/N2 selectivity of 19.8. Moreover, at 5 wt% loading of g-C3N4-D, the H2/N2 and O2/N2 separation of the MMMs had exceeded the 2008 Robeson upper bound, thanks to the periodic triangular ultramicropores in g-C3N4 that favor precise sieving of small gases. These results pave the way in using the developed membranes in practical H2 purification, air separation and CO2 capture.

Screening and characterization of an acid polysaccharide with antioxidant activity in vitro and in vivo from Dendrobium aurantiacum var. denneanum (Kerr)

Aim: We aimed to monitor an acid polysaccharide with antioxidant activity. Materials and Methods: Three acidic polysaccharides (DAP-A40, DAP-A60, and DAP-A80) were extracted from D. aurantiacum imbricate by alkaline aqueous solution extraction and ethanol precipitation. The structure characterization and antioxidant activity in vitro and in vivo were examined. Results: The molecular weight (MW) of three polysaccharides was 1.70 mol5 Da, 5.78 mol4 Da, and 1.36 mol4 Da, respectively, by high-performance gel chromatography. The consequences of infrared spectrum displayed that three polysaccharides enclosed uronic acid and sulfuric acid groups. DAP-A40 and DAP-A60 were collected of α-configuration pyranose. DAP-A80 was composed of β-configuration pyranose. Antioxidant test exhibited that DAP-A80 had outstanding antioxidant activity. The half-maximal inhibitory concentration of DAP-A80 in dipping power and scavenging the 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), DPPH, and OH radicals was 163.5 μg/mL, 613.2 μg/mL, 583.2 μg/mL, and 365.1 μg/mL, respectively. The grades of correlation analysis showed that the ability of DAP-A80 to scavenge ABTS, DPPH, and OH radicals was negatively connected with the MW of polysaccharides and certainly correlated with the content of sulfate group. The results of in vivo experiments exposed that DAP-A80 might knowingly decline the formation of malondialdehyde. High levels of DAP-A80 could evocatively upsurge the activity of superoxide dismutase and GSH-Px in mouse serum. Conclusion: DAP-A80 has an antioxidant effect and can be reconnoitered as a health medicine and food.

The response surface optimization of exopolysaccharide produced by Saccharomyces cerevisiae Y3 and its partial characterization

Response surface methodology (RSM) was used to optimize the conditions of exopolysaccharides (EPSs) by Saccharomyces cerevisiae Y3. The results indicated that the yield of EPS reached 4.52 ± 0.14 g/L with 10.30% (w/v) sucrose, 0.64% (w/v) yeast extract, liquid volume 141.5 mL, which was 2.40 times the original EPS yield. Y3 EPS contained 83.65 ± 0.16% of total sugars, 15.27 ± 0.26% of uronic acid, 0.78 ± 0.02% of protein and 0.30 ± 0.12% of sulfuric acid groups. Y3 EPS maintained a relatively low viscosity, with intrinsic viscosities of 306.58 mL/g (25 °C) and 200.91 mL/g (35 °C), respectively. The EPS had high water solubility index (WSI), high water holding capacity (WHC) and good emulsifying ability (EA). Meanwhile, the EPS could absorb metal ions such as Cu2+, Fe2+ and Zn2+. In addition, Y3 EPS exhibited good antioxidant properties and coagulated skim milk with a concentration-dependent manner. These results indicated that S. cerevisiae Y3 EPS had applicable prospects in medicine, food, especially the dairy industry.

Fabrication of PBI/SPOSS hybrid high-temperature proton exchange membranes using SPAEK as compatibilizer

Because of the harsh operating circumstances of high temperature over 100 °C and strong acidity, it is of great significance to explore some new methods on the developments of high-performance membrane materials using in high-temperature proton exchange membrane fuel cells (HT-PEMFCs). In current work, with the assistance of newly designed sulfonated poly (aryl ether ketone) (SPAEK) compatibilizer, some hydrophilic and acidophilic polyhedral-oligosilsesquioxane nanoparticles bearing sulfuric acid groups (SPOSS) were successfully incorporated into a soluble arylether-type polybenzimidazole (Ph-PBI) matrix via an in situ sol-gel process to obtain a new family of hybrid membranes with an improved overall performance. As a result, these hybrid membranes exhibited enhanced acid absorption ability and doping levels at 120 °C, improved acid retention ability and attractive mechanical-dimensional stability. More importantly, the proton conductivity of a phosphoric acid doped hybrid membrane reached 126 mS cm−1 at 200 °C. This membrane was also suitable for membrane electrode assemblies (MEAs), and a maximum power density of 300 mW cm−2 could be achieved at 160 °C without humidity.

Extraction, purification and characterization of sulphated polysaccharide from Bellamya quadrata and its stabilization roles on atherosclerotic plaque

The aim of this paper was to investigate the extraction, purification and characterization of sulphated polysaccharide (BQPS) from Bellamya quadrata and its stabilization roles on atherosclerotic plaque. Firstly, crude polysaccharide (CBQP) from Bellamya quadrata was extracted by protease enzyme assisted extraction. Moreover, its optimal parameters were obtained by the response surface method as follows: the ratio of water to raw material of 24:1, enzyme dosage of 285 U/g, enzymolysis pH value of 4.7 and temperature of 67 °C. Secondly, CBQP was further purified to obtain the target polysaccharide BQPS by Q Sepharose Fast Flow and Sephacryl S-400 gel column chromatography. Then, the characterization of BQPS revealed that it possessed a total polysaccharide content of 91.88 ± 1.23%, sulfuric acid group content of 9.12 ± 1.59% and molecular weight of 91.1 kDa. BQPS was only consisted of glucose without any proteins. Finally, BQPS was confirmed to have a significant stabilizing effect on atherosclerotic plaque and its mechanism was related to the selective promotion of autophagy with the precisely right strength.

Fucoidan: Biological Activity in Liver Diseases.

Fucoidan is a type of polysaccharide rich in sulfuric acid groups and is mainly found in brown algae. Due to its extensive biological activities, such as anticoagulant, antitumor, antithrombotic, antiviral, anti-oxidant and enhancing immune function, fucoidan has gradually become a research hotspot. Under the scientific guidance of modern medical theory, fucoidan and its mechanism in oxidative stress, carbohydrate and lipid metabolism, inflammatory response, tumor proliferation, and metastasis have become a new research direction and an important basis as an effective liver protection drug. In this paper, we discuss the important role of fucoidan in viral hepatitis, liver fibrosis, liver cancer, nonalcoholic fatty liver and liver injury induced by drugs and ischemia and briefly discuss its underlying mechanism. We supplement the theoretical basis for its clinical application and provide effective targets for the development of follow-up dominant drugs.

Extraction, Purification, Characterization, and Antiangiogenic Activity of Acidic Polysaccharide from Buddleja officinalis.

Firstly, optimal parameters of crude polysaccharide from Buddleja officinalis were obtained as follows: ratio of water to raw material of 26 : 1, ultrasonic power of 240 W, ultrasonic time of 45 min, and ultrasonic temperature of 62°C. Secondly, acidic polysaccharide (APBOM) from Buddleja officinalis was successfully acquired with the yield of 9.57% by using DEAE-52 cellulose and Sephadex G-100 gel column chromatography. Then, we found that total polysaccharide content of APBOM was 94.37% with a sulfuric acid group of 1.68%, uronic acid content of 17.41%, and average molecular weight of 165.4 kDa. Finally, APBOM was confirmed to have significant antiangiogenic effects.

Fabrication of proton exchange membranes and effect of sulfonated SiO2 (S-SiO2) in sulfonated polyether ether ketone (SPEEK) for fuel cells applications

The fabrication of composite proton exchange membrane from the sulfonated polyether ether ketone (SPEEK) and sulfonated SiO2 (S-SiO2) have been investigated for energy production. In this work, inorganic fillers have been incorporated successfully in the organic polymer matrix. The degree of sulfonation (DS) and ion exchange capacity (IEC) were measured by back titration method and observed around 46.4 % and 1.43 mmol/gm, respectively. DS and IEC were found is increase with the increase of the amount of S-SiO2 which reached to 56.5 % and 1.69 mmol/gm, respectively. Water uptake in percent was increased in the SPEEK/S-SiO2 membrane due to increasing the sulfuric acid groups (-SO3H), that lead to increasing the hydrophilic channels, the swelling ratio in percent was slightly increased. The proton conductivity of the SPEEK membrane was around 17.4 mS/cm and increased with increasing the amount of S-SiO2. The highest proton conductivity observed at SPEEK/0.3 S-SiO2 was around 53.7 mS/cm. suggesting its use in fuel cell for energy production.

Preparation and Characterization of Biomass Carbon–Based Solid Acid Catalysts for the Esterification of Marine Algae for Biodiesel Production

Biomass carbon derived from rice husk (RH), Moringa oleifera seeds (MOR), and biomass of lipid extracted marine algae (BM) bearing sulfuric acid groups, were investigated for the potential application to environmental benign biodiesel production. The physiochemical characteristics of the biomass-derived catalysts were determined with Fourier transform infrared spectroscopy, Raman spectroscopy, scanning electron microscopy, and X-ray diffraction techniques. These studies confirmed the presence of sulfur-incorporated functional groups on the carbonaceous materials. The SO3H-RH demonstrates the amorphous structure and higher surface area that enhances the possibility to attach –SO3H group. The acid site density of the catalysts was measured by utilizing ion exchange titration. It was found that SO3H-RH-based catalyst carries the most prominent acid site density (4.24 mmol/g by NaOH titration) when compared to other prepared solid acid catalysts. However, by employing SO3H-RH and SO3H-BM, almost full quantitative yield of ester was achieved with a 5 wt% mixture of catalyst/lipid for a reaction time of 20 min at a 5:1 M ratio of methyl alcohol/lipid extract. Whereas, they outperform the conventionally used sulfuric acid catalyst that gave 70% yield after 2 h under the same reaction condition. The results proved that the SO3H-RH has highly porous carbon structure and greater surface area that prominently enhances the acid site density. Therefore, SO3H-RH displays relatively better catalytic activity and stability when used compared to other solid acid and a sulfuric acid catalyst. The solid acid catalysts prepared from low-cost raw materials show enhance catalytic performance at room temperature and suitable for biodiesel production applications.

Structural characterization and antioxidant activity of polysaccharide from ginger

Two components ginger polysaccharide 1 (GP1) and ginger polysaccharide 2 (GP2) were extracted. The results showed that the molecular weights of GP1 and GP2 were 6128 Da and 12,619 Da, respectively. The composition and proportion of GP1 and GP2 were mannose, glucose and galactose in a molar ratio of 4.96: 92.24: 2.80 and arabinose, mannose, glucose and galactose in a molar ratio of 4.78: 16.70: 61.77: 16.75, respectively, illustrating that GP1 and GP2 were not a kind of homopolysaccharide. GP1 has a three-helix structure, and the structure is closely linked. GP2 contains sulfuric acid groups, and has a high oxidation resistance, its structure is more evacuated and messy.

Effect of Bisulfate, Ammonia, and Ammonium on the Clustering of Organic Acids and Sulfuric Acid.

We investigate the effect of the bisulfate anion HSO4-, ammonium cation NH4+, and ammonia NH3 on the clustering of sulfuric acid and pinic acid or 3-methyl-1,2,3-butanetricarboxylic acid (MBTCA). The systems were chosen based on their expected relevance in atmospheric new particle formation. Using quantum chemical methods together with kinetic calculations, we study the ability of these compounds to enhance cluster formation and growth. The cluster structures are obtained and frequencies are calculated using three different DFT functionals (M06-2X, PW91, and ωB97X-D) with the 6-31++G(d,p) basis set. The electronic energies are corrected using an accurate DLPNO-CCSD(T)/def2-QZVPP level of theory. The evaporation rates are evaluated based on the calculated Gibbs free energies. The interaction between the ions and sulfuric acid or carboxylic acid group is strong, and thereby small two-component ionic clusters are found to be very stable against evaporation. The presence of bisulfate stimulates the cluster formation through addition of the sulfuric acid, whereas the presence of ammonium favors the addition of organic acids. Bisulfate and ammonium enhance the first steps of cluster formation; however, at atmospheric conditions further cluster growth is limited due to the weak interaction and fast evaporation of the larger three-component clusters. On the basis of our results it is therefore unlikely that the studied organic acids and sulfuric acid, even together with bisulfate, ammonia, or ammonium can drive new-particle formation via clustering mechanisms. Other mechanisms such as chemical reactions are needed to explain observed new-particle formation events in the presence of oxidized organic compounds resembling the acids studied here.

Pyrolysis mechanisms of typical seaweed polysaccharides

The pyrolysis mechanisms of typical seaweed polysaccharides were investigated using TG-MS and Py-GC/MS. It was found that Enteromorpha polysaccharides (EN) was mainly composed of glucan, xylan and glucuronide-sulfate-rhamnose, while Sargassum fusiforme (SA) mainly consisted of uronic acid, sulfate group-fucose and polysaccharide galactose. Because of the component differences, it was found that the content of oxygen-containing functional groups and inorganic oxides varies. Meanwhile, three types of sulfur-containing functional groups (sulfonyl groups, sulphates, sulfate) were observed in seaweed polysaccharide. During the pyrolysis process, SO2 was generated because of the cleavage of sulfuric acid group in 4-O-glucuronide-2 sulfate-l-rhamnose. The generation of CO2 was due to the decarboxylation of organic matter. Besides, Py-GC/MS analysis indicated that the main pyrolysis products of EN polysaccharides were furans. The pyrolysis products of SA polysaccharides were mainly ester substances. Thus, the pyrolysis mechanisms as well as the generation pathways of main products of polysaccharides pyrolysis, were revealed.