Low Temperature Dissolution of Yeast Chitin-Glucan Complex and Characterization of the Regenerated Polymer

Chitin-glucan complex (CGC) is a copolymer composed of chitin and glucan moieties extracted from the cell-walls of several yeasts and fungi. Despite its proven valuable properties, that include antibacterial, antioxidant and anticancer activity, the utilization of CGC in many applications is hindered by its insolubility in water and most solvents. In this study, NaOH/urea solvent systems were used for the first time for solubilization of CGC extracted from the yeast Komagataella pastoris. Different NaOH/urea ratios (6:8, 8:4 and 11:4 (w/w), respectively) were used to obtain aqueous solutions using a freeze/thaw procedure. There was an overall solubilization of 63–68%, with the highest solubilization rate obtained for the highest tested urea concentration (8 wt%). The regenerated polymer, obtained by dialysis of the alkali solutions followed by lyophilization, formed porous macrostructures characterized by a chemical composition similar to that of the starting co-polymer, although the acetylation degree decreased from 61.3% to 33.9–50.6%, indicating that chitin was converted into chitosan, yielding chitosan-glucan complex (ChGC). Consistent with this, there was a reduction of the crystallinity index and thermal degradation temperature. Given these results, this study reports a simple and green procedure to solubilize CGC and obtain aqueous ChGC solutions that can be processed as novel biomaterials.

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Preparation and characterization of acetic acid lignin-based epoxy blends

BioResources ◽

10.15376/biores.7.3.2860-2870 ◽

2012 ◽

Vol 7 (3) ◽

pp. 2860-2870

Author(s):

Pan Feng ◽

Fangeng Chen

Keyword(s):

Acetic Acid ◽

Sodium Hydroxide ◽

Aqueous Sodium Hydroxide ◽

Diglycidyl Ether ◽

Degradation Temperature ◽

Acetic Acid Lignin ◽

Epoxy Blends ◽

Thermal Degradation Temperature ◽

Adhesive Shear Strength

Lignin-based epoxy resin (LER) was prepared from phenolated lignin (PL) and epichlorohydrin (ECH) in the presence of sodium hydroxide. The eucalyptus acetic acid lignin (AAL) was first reacted with phenol in the presence of sulfuric acid to obtain PL. Then, PL was reacted with ECH in aqueous sodium hydroxide to obtain LER. LER was mixed with diglycidyl ether of bisphenol A (E-44) and then cured with triethylenetetramine (TETA). The initial thermal degradation temperature (Td) of the cured epoxy blends decreased with the increase in LER content. The residue ratio at 500 °C of the cured epoxy blends (R500), however, increased with the LER content. The maximum adhesive shear strength of the cured epoxy blends was obtained at 20 wt% of LER. The water absorption of epoxy blends increased with increasing the content of LER. SEM photos showed that increasing the content of LER increased inhomogeneity and porosity of epoxy blends.

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Characterization of natural cellulosic fiber isolated from Malaysian Cymbopogan citratus leaves

BioResources ◽

10.15376/biores.16.4.7729-7750 ◽

2021 ◽

Vol 16 (4) ◽

pp. 7729-7750

Author(s):

Zatil Hafila Kamaruddin ◽

Ridhwan Jumaidin ◽

Ahmad Ilyas Rushdan ◽

Mohd Zulkefli Selamat ◽

Roziela Hanim Alamjuri

Keyword(s):

Chemical Composition ◽

Natural Fiber ◽

Morphological Characteristics ◽

Crystallinity Index ◽

Composition Analysis ◽

Green Composite ◽

X Ray Diffraction ◽

First Time ◽

Cymbopogan Citratus

A novel natural fiber derived from the Cymbopogan citratus plant was investigated for the first time. The characterization of the C. citratus fibers was conducted, and the chemical composition and physical, thermal, mechanical, crystallinity, and morphological characteristics were studied. The chemical composition analysis of Cymbopogan citratus fiber revealed that the suggested fiber was rich in cellulose contents (37.6%). The tensile test of C. citratus fiber demonstrated the fiber’s average tensile strength of 43.81 ± 15.27 MPa and modulus of elasticity of 1.046 ± 0.33 GPa. Further analysis with X-ray diffraction (XRD) confirmed that the crystallinity index of Cymbopogan citratus fiber was 35.2%, and the crystalline size was estimated as 4.28 nm. The Cymbopogan citratus fiber’s thermal stability was investigated via thermogravimetric analysis (TGA) and observed to be thermally stable (230 °C). A morphological investigation was employed on the fiber via a scanning electron microscope (SEM). The morphological study result exhibited that the fiber had a perforated and rough surface with the lumen in the center. Thus, the findings revealed that the Cymbopogan citratus fiber was a promising potential reinforcement for thermoplastic green composite applications.

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Synthesis and characterization of methyltetrahydrophthalic anhydride esterified corn starch by wet method

Materials Express ◽

10.1166/mex.2021.2026 ◽

2021 ◽

Vol 11 (7) ◽

pp. 1223-1230

Author(s):

Ting Luo ◽

Chengdong Yang ◽

Kang Zhang ◽

Yi Lin ◽

Fei Cheng ◽

...

Keyword(s):

Tensile Strength ◽

Corn Starch ◽

Light Transmittance ◽

Synthesis And Characterization ◽

Maximum Elongation ◽

Elongation At Break ◽

Degradation Temperature ◽

Methyltetrahydrophthalic Anhydride ◽

Thermal Degradation Temperature

The main purpose of this paper is to synthesize a novel esterified starch with an alicyclic structure. Herein, methyltetrahydrophthalic anhydride (MeTHPA), an alicyclic anhydride, was used to synthesize esterified corn starch (CS) with different degrees of substitution (DS) by a wet method. Compared with CS, the crystallinity and thermal degradation temperature of MeTHPA esterified CS (MeCS) decreased, while the hydrophobicity and light transmittance of MeCS films increased. The esterification modification significantly improved the toughness of the starch film. Between CS and MeCS films, the 15% Me/CS film shows a maximum elongation at break of 24.2% and a tensile strength of 8.0 MPa. Furthermore, 15% Me/CS was blended with CS as a sizing agent for polyester/cotton blended yarns and showed significantly increased adhesion to the blended yarns. Hence, the CS blended MeCS has a potential application in wrap sizing.

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Bio-Composites Reinforced with Strontium Titanate Nanoparticles: Mechanical Behavior and Degradability

Journal of Composites Science ◽

10.3390/jcs3010007 ◽

2019 ◽

Vol 3 (1) ◽

pp. 7 ◽

Cited By ~ 1

Author(s):

Amarilis Declet-Vega ◽

Nelson Sepúlveda-Ramos ◽

Sandra Crespo-Montoya ◽

Oscar Marcelo Suárez

Keyword(s):

Tensile Strength ◽

Strontium Titanate ◽

Cost Effective ◽

Tensile Tests ◽

Cellulose Content ◽

Acidic Solutions ◽

Degradation Temperature ◽

Elastic Coefficients ◽

Thermal Degradation Temperature

Bio-polymer-based composites are appealing cost-effective and environmentally friendly materials for electronic applications. This project relates to bio-composites made of chitosan and cellulose and reinforced with strontium titanate nanoparticles. Upon their fabrication, relevant parameters studied were the acetic acid concentration, the cellulose content, and the amount of strontium titanate nanoparticles. The specimens were characterized using thermogravimetric and degradation analyses, as well as via creep and tensile tests. The results revealed how higher cellulose levels lowered the ultimate tensile strength and the degradation temperature of the bio-composites. Moreover, when nanoparticles are present, higher cellulose levels contributed to their tensile strength. Additionally, more acidic solutions became detrimental to the mechanical properties and the thermal degradation temperature of the composites. Furthermore, the creep studies allowed determining elastic coefficients and viscous coefficients using the Burgers’ model. Those creep results suggest that higher amounts of SrTiO3 (STO) nanoparticles raised the composites creep strain rate. As a whole, the study provides a baseline characterization of these novel bio-composites when subject to aggressive environments.

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Characterization of machined polystyrene foam

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010015383x ◽

1989 ◽

Vol 47 ◽

pp. 372-373

Author(s):

C. W. Price ◽

E. F. Lindsey ◽

R. M. Franks ◽

M. A. Lane

Keyword(s):

Surface Finish ◽

Cell Walls ◽

Surface Structures ◽

Efficient Technique ◽

Low Density ◽

Polystyrene Foam ◽

Planar Surfaces ◽

Machining Characteristics

Diamond-point turning is an efficient technique for machining low-density polystyrene foam, and the surface finish can be substantially improved by grinding. However, both diamond-point turning and grinding tend to tear and fracture cell walls and leave asperities formed by agglomerations of fragmented cell walls. Vibratoming is proving to be an excellent technique to form planar surfaces in polystyrene, and the machining characteristics of vibratoming and diamond-point turning are compared.Our work has demonstrated that proper evaluation of surface structures in low density polystyrene foam requires stereoscopic examinations; tilts of + and − 3 1/2 degrees were used for the stereo pairs. Coating does not seriously distort low-density polystyrene foam. Therefore, the specimens were gold-palladium coated and examined in a Hitachi S-800 FESEM at 5 kV.

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TBE in Sweden

Tick-borne encephalitis - The Book ◽

10.33442/26613980_12b32-3 ◽

2020 ◽

Keyword(s):

Genetic Characterization ◽

Immunoglobulin M ◽

Enzyme Linked Immunosorbent Assay ◽

Second Phase ◽

Serum Samples ◽

Tick Borne Encephalitis ◽

Specific Immunoglobulin ◽

Tick Borne Encephalitis Virus ◽

First Time

Tick-borne encephalitis virus (TBEV) was isolated for the first time in Sweden in 1958 (from ticks and from 1 tick-borne encephalitis [TBE] patient).1 In 2003, Haglund and colleagues reported the isolation and antigenic and genetic characterization of 14 TBEV strains from Swedish patients (samples collected 1991–1994).2 The first serum sample, from which TBEV was isolated, was obtained 2–10 days after onset of disease and found to be negative for anti-TBEV immunoglobulin M (IgM) by enzyme-linked immunosorbent assay (ELISA), whereas TBEV-specific IgM (and TBEV-specific immunoglobulin G/cerebrospinal fluid [IgG/CSF] activity) was demonstrated in later serum samples taken during the second phase of the disease.

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UV Curable Organic-Inorganic Hybrid Materials

MRS Proceedings ◽

10.1557/proc-628-cc6.14 ◽

2000 ◽

Vol 628 ◽

Cited By ~ 1

Author(s):

Guang-Way Jang ◽

Ren-Jye Wu ◽

Yuung-Ching Sheen ◽

Ya-Hui Lin ◽

Chi-Jung Chang

Keyword(s):

Hybrid Materials ◽

Colloidal Silica ◽

Sol Gel ◽

Solution Ph ◽

Uv Curable ◽

Inorganic Hybrid ◽

Degradation Temperature ◽

Sol Gel Process ◽

The Stability ◽

Thermal Degradation Temperature

This work successfully prepared an UV curable organic-inorganic hybrid material consisting of organic modified colloidal silica. Applications of UV curable organic-inorganic hybrid materials include abrasion resistant coatings, photo-patternable thin films and waveguides. Colloidal silica containing reactive functional groups were also prepared by reacting organic silane and tetraethyl orthosilicate (TEOS) using sol-gel process. In addition, the efficiency of grafting organic moiety onto silica nanoparticles was investigated by applying TGA and FTIR techniques. Experimental results indicated a strong interdependence between surface modification efficiency and solution pH. Acrylate-SiO2 hybrid formation could result in a shifting of thermal degradation temperature of organic component from about 200°C to near 400°C. In addition, the stability of organic modified colloidal silica in UV curable formula and the physical properties of resulting coatings were discussed. Furthermore, the morphology of organic modified colloidal silica was investigated by performing TEM and SEM studies‥

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Chemical Constituents and Antibacterial Activity of Cissus Aralioides.

Letters in Organic Chemistry ◽

10.2174/1570178617999200609130127 ◽

2020 ◽

Vol 17 ◽

Author(s):

Balogun Olaoye Solomon ◽

Ajayi Olukayode Solomon ◽

Owolabi Temitayo Abidemi ◽

Oladimeji Abdulkarbir Oladele ◽

Liu Zhiqiang

Keyword(s):

Plant Extract ◽

Chemical Constituents ◽

Ethyl Acetate Fraction ◽

Antibacterial Activities ◽

Sub Saharan Africa ◽

Chromatographic Purification ◽

Whole Plant ◽

Sub Saharan ◽

First Time

: Cissus aralioides is a medicinal plant used in sub-Saharan Africa for treatment of infectious diseases; however the chemical constituents of the plant have not been investigated. Thus, in this study, attempt was made at identifying predominant phytochemical constituents of the plant through chromatographic purification and silylation of the plant extract, and subsequent characterization using spectroscopic and GC-MS techniques. The minimum inhibitory concentration (MICs) for the antibacterial activities of the plant extract, chromatographic fractions and isolated compounds were also examined. Chromatographic purification of the ethyl acetate fraction from the whole plant afforded three compounds: β-sitosterol (1), stigmasterol (2) and friedelin (3). The phytosterols (1 and 2) were obtained together as a mixture. The GC-MS analysis of silylated extract indicated alcohols, fatty acids and sugars as predominant classes, with composition of 24.62, 36.90 and 26.52% respectively. Results of MICs indicated that friedelin and other chromatographic fractions had values (0.0626-1.0 mg/mL) comparable with the standard antibiotics used. Characterization of natural products from C. aralioides is being reported for the first time in this study.

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Green Synthesis and Spectroscopic Studies of Ag-rGO Nanocomposites for Highly Selective Mercury (II) Sensing

Nanoscience &Nanotechnology-Asia ◽

10.2174/2210681207666170705143629 ◽

2018 ◽

Vol 9 (1) ◽

pp. 101-108 ◽

Cited By ~ 1

Author(s):

Shubhangi J. Mane-Gavade ◽

Sandip R. Sabale ◽

Xiao-Ying Yu ◽

Gurunath H. Nikam ◽

Bhaskar V. Tamhankar

Keyword(s):

Green Synthesis ◽

Color Change ◽

Limit Of Detection ◽

Aqueous Media ◽

Suitable Condition ◽

Cost Effective ◽

Spectroscopic Studies ◽

Calibration Plot ◽

First Time

Introduction: Herein we report the green synthesis and characterization of silverreduced graphene oxide nanocomposites (Ag-rGO) using Acacia nilotica gum for the first time. Experimental: We demonstrate the Hg2+ ions sensing ability of the Ag-rGO nanocomposites form aqueous medium. The developed colorimetric sensor method is simple, fast and selective for the detection of Hg2+ ions in aqueous media in presence of other associated ions. A significant color change was noticed with naked eye upon Hg2+ addition. The color change was not observed for cations including Sr2+, Ni2+, Cd2+, Pb2+, Mg2+, Ca2+, Fe2+, Ba2+ and Mn2+indicating that only Hg2+ shows a strong interaction with Ag-rGO nanocomposites. Under the most suitable condition, the calibration plot (A0-A) against concentration of Hg2+ was linear in the range of 0.1-1.0 ppm with a correlation coefficient (R2) value 0.9998. Results & Conclusion The concentration of Hg2+ was quantitatively determined with the Limit of Detection (LOD) of 0.85 ppm. Also, this method shows excellent selectivity towards Hg2+ over nine other cations tested. Moreover, the method offers a new cost effective, rapid and simple approach for the detection of Hg2+ in water samples.

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Waste-Based One-Part Alkali Activated Materials

Materials ◽

10.3390/ma14112911 ◽

2021 ◽

Vol 14 (11) ◽

pp. 2911

Author(s):

Margarida Gonçalves ◽

Inês Silveirinha Vilarinho ◽

Marinélia Capela ◽

Ana Caetano ◽

Rui Miguel Novais ◽

...

Keyword(s):

Compressive Strength ◽

Microstructural Analysis ◽

Construction Materials ◽

Sodium Metasilicate ◽

High Compressive Strength ◽

Hardened State ◽

First Time ◽

Furnace Slag ◽

Alkali Activated

Ordinary Portland Cement is the most widely used binder in the construction sector; however, a very high carbon footprint is associated with its production process. Consequently, more sustainable alternative construction materials are being investigated, namely, one-part alkali activated materials (AAMs). In this work, waste-based one-part AAMs binders were developed using only a blast furnace slag, as the solid precursor, and sodium metasilicate, as the solid activator. For the first time, mortars in which the commercial sand was replaced by two exhausted sands from biomass boilers (CA and CT) were developed. Firstly, the characterization of the slag and sands (aggregates) was performed. After, the AAMs fresh and hardened state properties were evaluated, being the characterization complemented by FTIR and microstructural analysis. The binder and the mortars prepared with commercial sand presented high compressive strength values after 28 days of curing-56 MPa and 79 MPa, respectively. The mortars developed with exhausted sands exhibit outstanding compressive strength values, 86 and 70 MPa for CT and CA, respectively, and the other material’s properties were not affected. Consequently, this work proved that high compressive strength waste-based one-part AAMs mortars can be produced and that it is feasible to use another waste as aggregate in the mortar’s formulations: the exhausted sands from biomass boilers.

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